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Human Anatomy 1
human anatomy
| body regions yu | Answer |
|---|---|
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| Skeletal system is composed of how many components? | Bones The rigid framework of the body Cartilage A flexible connective tissue that cushions joints and helps bones move smoothly. Ligaments connect bone to bone |
| define anatomical positions anterior and posterior medial and lateral | Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline (center) of the body Lateral Away from the midline |
| anatomical position continue proximal and distal superior and inferior | Proximal Closer to the point of attachment or origin Distal Farther from the point of attachment or origin Superior toward the head inferior toward the feet |
| Body Cavities Dorsal Ventral | dorsal Cranial cavity: brain Spinal (vertebral) cavity: spinal cord Ventral Thoracic lungs pericardial cavity the heart pleural cavities lungs |
| Abdominal Cavity pelvic cavities | abdominal liver gallbladder stomach pancreas intesteen spleen kidneys ureter pelvic urinary bladder, female reproductive system male reproductive system |
| body regions you dont know | acromial shoulder antecubital area in front of the elbow calcaneal heel of foot coxal hip crural leg cubital elbow digital fingers and toes hallux big toe |
| what is homeostasis | is the process by which living organisms maintain a stable internal environment despite changes in the external environment. |
| The body as a whole can be subdivided into two major divisions. They are | axial and appendicular. |
| carbohydrates | glucose simple sugar, stores energy, ex: blood glucose Ribose simple sugar,expressing hereditary info ex rna deoxyribose storage and transmission of hereditary info DNA glycogen , glucose, stores energy ex: liver glycogen |
| Lipids | triglyceride,, stores energy, ex body fat phospholipids,, make up cell membrane ex plasma membrane of cell steroids, make up cell membrane and hormone synthesis ex cholesterol & steroid hormones estrogen prostaglandin regulates hormone action |
| proteins | functional regulates chemical reaction structural components of body support tissue |
| nuclear acids | DNA encodes hereditary information RNA helps decode hereditary information trnasfer RNA |
| body regions you dont know | acromial shoulder antecubital area in front of the elbow calcaneal heel of foot coxal hip crural leg cubital elbow digital fingers and toes hallux big toe |
| what is homeostasis | is the process by which living organisms maintain a stable internal environment despite changes in the external environment. |
| The body as a whole can be subdivided into two major divisions. They are | axial and appendicular. |
| carbohydrates | glucose simple sugar, stores energy, ex: blood glucose Ribose simple sugar,expressing hereditary info ex rna deoxyribose storage and transmission of hereditary info DNA glycogen , glucose, stores energy ex: liver glycogen |
| Lipids | triglyceride,, stores energy, ex body fat phospholipids,, make up cell membrane ex plasma membrane of cell steroids, make up cell membrane and hormone synthesis ex cholesterol & steroid hormones estrogen prostaglandin regulates hormone action |
| proteins | functional regulates chemical reaction structural components of body support tissue |
| nuclear acids | DNA encodes hereditary information RNA helps decode hereditary information trnasfer RNA (tRNA) messenger RNA(mRNA) double standard RNA (dsRNA) |
| Plasma membrane Phospholipid bilayer reinforced with cholesterol and embedded with proteins and other organic molecule | funtion Acts like the skin of the cell, keeping everything inside and protecting it ID tags that help the body recognize its own cells move substances in and out of the cell. |
| Endoplasmic reticulum (ER) Network of canals and sacs extending from the nuclear envelope; may have ribosomes attached | Rough ER has ribosomes that make proteins. These proteins enter the ER to be folded and finished Makes fats and proteins for cell membranes, Produces steroid hormones, Helps detoxify harmful substances Regulates sugar (glycogen) enzymes, |
| Golgi apparatus Stack of flattened sacs (cisternae) surrounded by vesicles | Synthesizes carbohydrate, combines it with protein, and packages the product as globules of glycoprotein |
| Vesicles Tiny membranous bags | Temporarily contain molecules for transport or later use |
| Lysosomes Tiny membranous bags containing enzymes | Act like the cell’s digestive system. Use enzymes to break down damaged parts and digest unwanted materials (called autophagy). Also help with membrane repair and secretion |
| Peroxisomes Tiny membranous bags containing enzymes | Tiny membranous bags containing enzymes |
| Mitochondria Tiny membranous capsule surrounding an inner, highly folded membrane embedded with enzymes; has small, ringlike chromosome (DNA | Catabolism; adenosine triphosphate (ATP) synthesis; a cell’s “power plants” |
| Nucleus usually central, spherical double-membrane container of chromatin (DNA); has large pores | The nucleus holds the cell’s genetic code (DNA). DNA gives instructions for making proteins. These proteins help control important cell activities like: Transport Metabolism Growth |
| MBRANE FUNCTION Embedded within the phospholipid bilayer are a variety of integral membrane proteins (IMPs) | IMPs are proteins embedded in the cell membrane. They stay stable because they have parts that like water (hydrophilic) and parts that don’t (hydrophobic). These proteins have different shapes and jobs |
| Functions of IMPs | Transport Act like gates that control what enters or leaves the cell. Only certain molecules can pass through, and the cell decides when the gates open or close |
| function of IMP | Identification Some IMPs have sugar chains attached, forming glycoproteins. These act like ID tags so the immune system can tell which cells belong and which don’t. Helps fight disease and match blood types safely. |
| function of IMP | Signaling Some IMPs are receptors that detect signals like hormones. They trigger changes inside the cell — a process called signal transduction. This is key to understanding how cells respond and how diseases are treated. |
| function of IMP | Connection IMPs can link cells together to form tissues. They also connect the membrane to the cell’s internal structure or to the extracellular matrix (ECM) outside the cell. |
| cell connections What Holds Cells Together? | Attachment to the Matrix Cells stick to the extracellular matrix Proteins called integrins help anchor cells by linking the inside of the cell to the outside fibers |
| cell connections What Holds Cells Together? | Direct Cell-to-Cell Connections Cells also connect directly to each other using special proteins like:Integrins Selectins Cadherins Immunoglobulins |
| Types of Cell Connections | Desmosomes Act like Velcro: tiny fibers from neighboring cells interlock. Found in skin cells. Can be spot-like or belt-like (called belt desmosomes or zona adherens). |
| Types of Cell Connections | Gap Junctions Create tunnels between cells. Let molecules and electrical signals pass directly from one cell to another. Important in heart muscle, where signals need to spread quickly. |
| Types of Cell Connections | Tight Junctions Seal cells together near the top (apical surface). Like a six-pack ring, they hold cells tightly so nothing leaks between them. Found in places like the intestines, where control over what passes through is crucial. |
| Membrane Transport | Cells need to move substances like ions and molecules: Inside the cell, Across the cell membrane, Between compartments Move directly through the membrane’s phospholipid bilayer Others use transport proteins (like gates) to pass through |
| Types of Transport | Passive Transport No energy needed Molecules move using their own energy Active Transport Requires energy from the cell Molecules are actively carried across the membrane |
| Diffusion is the movement of molecules from a high concentration to a low concentration It happens naturally as molecules bounce around and spread out. Example: Sugar dissolving in water spreads evenly over time. | Molecules naturally spread out from crowded areas to less crowded ones. Molecules move down a concentration gradient — from high to low concentration The steeper the gradient, the faster the movement. |
| Solute and Water Movement | If one side of a membrane has 20% sugar and the other has 10% sugar: Sugar (solute) moves from 20% → 10% Water moves from 10% → 20% because the 10% side is more watery (dilute). Eventually, both sides become equal — this is called equilibrium. |
| Dynamic Equilibrium | Even at equilibrium, molecules keep moving back and forth. The number moving in each direction stays balanced. |
| Simple Diffusion | Some molecules pass directly through the cell membrane: Small, lipid-soluble molecules like (O₂) and (CO₂) move easily. Small, uncharged molecules (H₂O) and urea move slightly. If a membrane allows molecules to pass, it’s called permeable. |
| What Is Osmosis | Osmosis is the movement of water through a semipermeable membrane. The membrane lets water pass but blocks certain solutes (like sugar or salt). Water moves from the side with less solute (more watery) to the side with more solute. |
| How Water Moves Through Cell Membranes | Water doesn’t pass easily through the membrane’s fatty layer. Special proteins called aquaporins (water channels) help water move across. |
| Effects of Osmosis on Red Blood Cells | Hypotonic Cell swells or bursts Water moves into the cell (more water outside) Isotonic Cell stays normal Water moves in and out equally Hypertonic Cell shrinks (crenates) Water moves out of the cell (more solute outside) |
| Membrane Channels are like tiny tunnels in the cell membrane. | Each channel is specific — only certain ions or molecules can pass through: Na⁺ uses sodium channels Cl⁻ uses chloride channels |
| Membrane Channels are like tiny tunnels in the cell membrane. | Water uses aquaporins (also called aquapores) These channels can be open or closed, controlling what enters or exits the cell. Movement through these channels is passive — from high to low concentration. |
| Types of Passive Transport: | Simple Diffusion Molecules pass directly through the membrane (e.g., oxygen, CO₂). Facilitated Diffusion Molecules use transport proteins (channels or carriers) to cross. |
| Types of Passive Transport: | Osmosis Water moves through aquaporins from low solute to high solute areas. Filtration Water and small particles move through a membrane due to fluid pressure. |
| Transport by Vesicles | Vesicles are small membrane “bags” that carry molecules into or out of the cell. This process uses energy, just like active transport. Vesicles move substances without passing directly through the membrane. |
| Endocytosis – Bringing Stuff Into the Cell | The cell traps material from outside and pulls it in using the cytoskeleton. The membrane folds in, forms a vesicle, and brings the material inside. |
| Types of Endocytosis | Receptor-mediated Uses receptors to grab specific molecules (e.g., insulin, cholesterol) Phagocytosis “Cell eating” – takes in large particles like bacteria Pinocytosis “Cell drinking” – takes in fluids and dissolved substances |
| What Are Enzymes? | Enzymes are special proteins that speed up chemical reactions in the body. |
| How Enzymes Work | Each enzyme has an active site — a spot that fits a specific molecule (called a substrate). The enzyme and substrate fit together like a lock and key. |
| Enzymes can | Join molecules together Break molecules apart Change the shape or structure of molecules |
| Enzyme Structure | Enzymes are complex proteins (tertiary or quaternary). Some have cofactors (helpers): Inorganic (like metal ions) Organic (called coenzymes, often vitamins) |
| Types of Enzymes (by function) | Hydrolases Break down molecules using water (e.g., digestive enzymes like sucrase) Phosphorylases/Phosphatases Add or remove phosphate groups Carboxylases/Decarboxylases Add or remove carbon dioxide |
| Types of Enzymes (by function) | Mutases/Isomerases Rearrange atoms within a molecule Hydrases Add water without splitting the molecule Oxidases/Dehydrogenases Help release energy through redox reactions |
| Why Enzymes Matter | Enzymes control metabolic pathways — chains of reactions that keep cells alive and functioning. Without enzymes, these pathways wouldn’t work properly. |
| Effects of pH and Temperature | Enzymes work best in a specific pH and temperature range: Pepsin (in stomach) works in low pH Trypsin (in pancreas) works in higher pH Most enzymes work best around 40°C |
| negative feedback loop it prevents the cell from making too much of something. | When enough product is made, it can bind to the enzyme and slow down or stop the process. |
| Proenzymes and Kinases | Some enzymes are made in an inactive form (called proenzymes). Kinases activate them by changing their shape. Example: Enterokinase activates trypsinogen into trypsin Kinase A activates enzymes in response to hormones |
| Catabolism is the process of breaking down molecules to release energy. | The most important catabolic pathway is cellular respiration, which breaks down glucose into carbon dioxide (CO₂) and water (H₂O). This releases energy, some as heat, and some stored in ATP (the cell’s energy molecule). |
| Cellular Respiration 1 | Glycolysis Happens in the cytosol (fluid part of the cell). Breaks glucose (6-carbon) into pyruvate (3-carbon). Does not need oxygen (anaerobic). Produces a small amount of ATP and NADH (another energy carrier). |
| Cellular Respiration 2 | Citric Acid Cycle (if oxygen is available) Pyruvate enters this cycle. Needs oxygen (aerobic). Produces more ATP, NADH, and CO₂. |
| Cellular Respiration 3 | Electron Transport System Uses NADH to make a large amount of ATP. Also needs oxygen. |
| What Happens Without Enough Oxygen? | Pyruvate turns into lactate (lactic acid). This happens during intense exercise or when oxygen is low (like in blocked heart cells). |
| What Happens Without Enough Oxygen? 2 | Lactate builds up but can later be: Turned back into pyruvate or glucose Used by other cells (like heart or brain) for energy |
| What Is Mitosis? Mitosis is the process of dividing a cell’s nuclear DNA so each new cell gets a complete copy. | t happens in four phases and is followed by cytokinesis (splitting the cell in two). Before mitosis, the cell is in interphase, where it prepares by copying DNA and centrosomes. |
| Phases of Mitosis 1Prophase | Prophase – "Prep Phase" Chromosomes form from coiled DNA. Nuclear envelope breaks down. Centrosomes move to opposite ends of the cell. Spindle fibers begin to form. |
| Phases of Mitosis 2 Metaphase | Metaphase – "Middle Phase" Chromosomes line up at the center (equator) of the cell. Each chromatid attaches to a spindle fiber. |
| Phases of Mitosis 3 Anaphase | Anaphase – "Apart Phase" Centromeres split, separating sister chromatids. Chromatids (now full chromosomes) are pulled to opposite poles of the cell. |
| Phases of Mitosis 4 final phase Telophase – "End Phase | New nuclear envelopes form around each set of DNA. Chromosomes uncoil back into chromatin (loose DNA). |
| Phases of Mitosis 4 final phase Telophase – "End Phase part 2 | Spindle fibers disappear — they’re no longer needed. Cytokinesis finishes, splitting the cell into two identical daughter cells. Each new cell enters interphase, ready to grow and function. |
| Meiosis is a special type of cell division that makes sex cells (gametes). | It happens only in primitive sex cells: In males: spermatogonia → sperm In females: oogonia → ova (eggs) |
| Chromosome Numbers | Regular body cells (somatic cells) have 46 chromosomes → called the diploid number. Sex cells (gametes) have 23 chromosomes → called the haploid number. |
| Chromosome Numbers after fertilization | After fertilization, the sperm and egg combine to form a zygote with 46 chromosomes (23 from each parent). |
| Steps of Meiosis | Meiosis I: Chromosome number is cut in half (from 46 to 23), but chromatids stay together. Meiosis II: Chromatids split apart, creating mature gametes. |
| After Fertilization | The zygote begins dividing by mitosis to form a human body. Cells specialize into different types (like muscle, nerve, skin). Some cells enter a resting phase called G₀, where they stop dividing and focus on maintenance |
| What Are Epithelial Membranes? | Epithelial membranes are made of: A top layer of epithelial cells A bottom layer of connective tissue |
| Epithelial Membranes? 3 main types 1 | Cutaneous Membrane (Skin) Covers the outside of the body Part of the integumentary system Contains sweat and oil glands Makes up about 16% of body weight Protects the body and helps regulate temperature |
| type 2 Serous Membranes | Line internal body cavities (not open to the outside) Cover organs inside those cavities Made of: Simple squamous epithelium Thin connective tissue |
| Serous Membranes | Secrete watery fluid to reduce friction Two layers: Parietal layer: lines the cavity wall Visceral layer: covers the organ |
| Mucous Membranes | Line body surfaces that open to the outside Found in: Respiratory tract Digestive tract Urinary tract Reproductive tract |
| Epithelium type depends on location | Stratified squamous (e.g., esophagus) Simple columnar (e.g., intestines) |
| continue | Stratified squamous (e.g., esophagus) Simple columnar (e.g., intestines) |
| Connective Tissue Membranes | Unlike other membranes (like skin or mucous membranes), connective tissue membranes have no epithelial layer. The main type is the synovial membrane. |
| Synovial Membranes | Found in movable joints (like knees, elbows, fingers). Also line bursae — small sacs that cushion movement between bones, muscles, and tendons. |
| Synovial Membranes continue | They are: Smooth and slick Secrete synovial fluid — a thick, clear lubricant Function: Reduce friction between moving parts |
| Types of Epithelial Tissue 1.Membranous Epithelium | Covers the body and lines internal cavities and tubes Found in: skin, blood vessels, respiratory, digestive, urinary, and reproductive tracts |
| Glandular Epithelium | Forms glands that produce secretions Found in: endocrine and exocrine glands (e.g., sweat, mucus, hormones) |
| Functions of Epithelial Tissue | Protection: Shields the body from injury and germs (e.g., skin) Sensation: Found in sensory organs like the nose, eyes, and ears Secretion: Produces substances like sweat, mucus, and hormones |
| Functions of Epithelial Tissue continues | Absorption: Takes in nutrients and gases (e.g., intestines, lungs) Excretion: Helps remove waste (e.g., kidney tubules) |
| Types of Epithelial Cell Shapes 1 Squamous Cells | Flat and thin like scales Good for covering surfaces and allowing quick exchange (e.g., lungs, blood vessels) |
| Types of Epithelial Cell Shapes 2 Cuboidal Cells | Cube-shaped with more cytoplasm Often found in glands and kidney tubules |
| Types of Epithelial Cell Shapes 3 Columnar Cells | Tall and narrow like columns Found in areas that do absorption and secretion (e.g., intestines) |
| Types of Epithelial Cell Shapes 4Pseudostratified Columnar Cells | Look like they’re in layers, but they’re actually one layer All cells touch the basement membrane, but not all reach the surface Nuclei are at different heights, giving a false layered look Common in the respiratory tract |
| Simple Epithelium | One layer of cells Allows easy diffusion, filtration, absorption, and secretion |
| Simple Epithelium Types: | Simple squamous: flat cells; found in lungs, blood vessels, and body cavity linings Simple cuboidal: cube-shaped cells; found in glands, ducts, and kidney tubules |
| Simple Epithelium Types: | Simple columnar: tall, narrow cells; found in stomach, intestines, uterus, and respiratory tract May include: Goblet cells (produce mucus) Cilia (move substances) Microvilli (increase surface area for absorption) |
| Stratified Epithelium | Multiple layers of cells Provides protection in areas with more wear and tear Named by the shape of the top layer of cells |
| Transitional Epithelium | A special type of stratified epithelium Cells can change shape (stretch and return) Found in areas like the bladder |
| Goblet Cells and Mucus | Goblet cells are special cells that produce mucus. Mucus is made of water, electrolytes, and proteoglycans. It helps with lubrication and protection of epithelial surfaces. |
| Cilia | Cilia are tiny, hair-like structures on some epithelial cells. They are supported by microtubules inside the cell. Cilia can: Sense changes in the environment Move substances across the cell surface (like mucus in the airways) |
| Microvilli | Microvilli are short, fingerlike projections on the surface of some epithelial cells. Found especially in the intestines. Their job is to increase surface area to help absorb nutrients and fluids. They are shorter and more numerous than cilia. |
| Pseudostratified Columnar Epithelium | Appears layered (stratified) but is actually one single layer. All cells touch the basement membrane, but not all reach the surface. Nuclei are at different levels, giving a false layered look. |
| Pseudostratified Columnar Epithelium found in | Respiratory tract (e.g., trachea) Parts of the male reproductive system (e.g., urethra) |
| Transitional Epithelium (Urothelium) Protects organs from tearing during expansion | Found in areas that stretch, like the urinary bladder. Made of many layers of cuboidal cells when relaxed. Umbrella cells are the top layer — wide and curved, sometimes with more than one nucleus. |
| Glandular Epithelium | Specialized for secretion Can be: Unicellular (single cells like goblet cells) Multicellular (clusters, cords, or tubes) |
| Glandular Epithelium Two Types of Glands: | Exocrine Secretes into ducts Salivary glands (saliva to mouth) Endocrine Secretes directly into blood or fluid Pituitary, thyroid, adrenal (hormones) |
| Functional Classification of Exocrine Glands 1 Apocrine | Part of the cell pinches off with the secretion Found in sweat glands of the armpits and groin |
| Functional Classification of Exocrine Glands 2 Holocrine | Cell fills with product, then ruptures to release it Example: sebaceous (oil) glands in the skin |
| Functional Classification of Exocrine Glands 3 Merocrine | Secretion passes through the cell membrane without damage Most common type Example: salivary glands |
| Adipose Tissue | A type of connective tissue made mostly of fat cells called adipocytes Stores triglycerides (fat) in large vesicles that push the cell’s contents outward Releases the hormone leptin, which tells the brain how much fat is stored |
| Adipose Tissue types 1. White Fat | Most common type Stores energy Insulates the body and helps retain heat Protects organs like kidneys Helps with buoyancy in water |
| Adipose Tissue types 2. Brown Fat | Less common, found mostly in newborns Burns fat to generate heat Contains many small fat vesicles and mitochondria Helps regulate body fat in adults |
| Adipose Tissue types 3. Beige Fat | ound within white fat Some white fat cells convert to brown-like cells Helps generate heat when the body gets cold Supports the body’s temperature control system |
| Reticular Tissue? | A type of connective tissue with a net-like (reticular) structure Made of thin, branching fibers called reticulin and reticular cells |
| Reticular Tissue? Where It’s Found | Spleen Lymph nodes Bone marrow These places are part of the immune and blood-forming systems. |
| Reticular Tissue? What It Does | Forms a supportive framework for soft organs Filters harmful substances from blood and lymph Reticular cells can: Engulf and destroy harmful particles (phagocytosis) Produce reticular fibers |
| Dense Fibrous Tissue? | Made mostly of tightly packed fibers Contains few cells (mostly fibroblasts) Provides strength and support |
| Two Types Based on Fiber Arrangement 1 Dense Irregular Fibrous Tissue | Fibers are arranged in swirling, random patterns Can resist stress from any direction Found in: Dermis (inner skin layer) Organ capsules (e.g., kidney, spleen) Fascia around muscles |
| Two Types Based on Fiber Arrangement 2Dense Regular Fibrous Tissue | ibers are arranged in parallel rows Very strong and flexible when pulled in one direction Found in: Tendons (connect muscle to bone) Ligaments (connect bone to bone; more elastic) |
| Cartilage A type of connective tissue with only one cell type: chondrocytes | Chondrocytes sit in small spaces called lacunae Cartilage is avascular (no blood vessels), so nutrients move in by diffusion Surrounded by a membrane called the perichondrium Heals slowly due to limited blood supply |
| Types of Cartilage 1 Hyaline Cartilage | Smooth, glassy appearance Most common type Found in: Respiratory tubes (like trachea rings) Ends of bones at joints |
| Types of Cartilage 2Fibrocartilage | Strongest and most durable type Packed with collagen fibers Acts as a shock absorber Found in: Intervertebral discs Knee joints (menisci |
| Types of Cartilage 3. Elastic Cartilage | Contains many elastic fibers Very flexible Found in: External ear Larynx (voice box) |
| What Is Blood Tissue? A liquid connective tissue with no fibers or ground substance | Made of: Plasma (liquid part) – about 55% Formed elements (cells) – about 45% |
| Types of Blood Cells | Red blood cells (erythrocytes) – carry oxygen and carbon dioxide White blood cells (leukocytes) – fight infections Platelets (thrombocytes) – help with blood clotting |
| Functions of Blood | Transports gases, nutrients, and waste Helps regulate body temperature and pH levels Supports the immune system |
| What Is Muscle Tissue? | Muscle tissue is specialized for movement. It contains microfilaments that allow cells to contract and relax with force. There are three types of muscle tissue in the body: |
| What Is Muscle Tissue? 1. Skeletal Muscle | Attached to bones Also called striated voluntary muscle Has visible stripes (striations) Controlled by conscious effort Long fibers (up to 40,000 μm) |
| What Is Muscle Tissue? 2. Smooth Muscle | Found in walls of internal organs (e.g., stomach, intestines, blood vessels) Also called nonstriated involuntary muscle No visible stripes Controlled automatically (not by will) Shorter, spindle-shaped fibers (tapered ends, about 500 μm long) |
| What Is Muscle Tissue? 3. Cardiac Muscle | Found only in the heart Also called striated involuntary muscle Has stripes and intercalated disks (dark bands that connect cells) Cells branch and connect to form a network called a syncytium Contracts automatically and rhythmically |
| What Is Nervous Tissue? | Nervous tissue allows the body to communicate quickly and coordinate activities. Found in the brain, spinal cord, and nerves. It’s the most excitable and conductive tissue in the body. |
| Two Main Cell Types 1Neurons – the main signal-carrying cells | Have a cell body (soma) Dendrites bring signals in Axon sends signals out Mostly found in the central nervous system |
| Two Main Cell Types 2 Neuroglia – support and protect neurons | Astrocytes: regulate neuron function and protect from toxins Microglia: destroy germs and damaged cells Schwann cells and oligodendrocytes: insulate axons to speed up signals |
| Main Cell Types in the Epidermis 1Keratinocytes | Make up 90% of epidermal cells Produce keratin, a tough protein that protects the skin Once dead and fully keratinized, they’re called corneocytes |
| Main Cell Types in the Epidermis 2 Melanocytes | Make pigment (melanin) that gives skin its color Help protect against UV radiation Make up about 5% of epidermal cells |
| Main Cell Types in the Epidermis 3 Epidermal Dendritic Cells (Langerhans Cells) | Part of the immune system Detect and present foreign invaders (like bacteria) to other immune cells Come from the bone marrow |
| Main Cell Types in the Epidermis 4Tactile Epithelial Cells (Merkel Cells) | Found in the deepest layer of the epidermis Connected to nerve endings Act as touch receptors for sensing light pressure |
| Layers of the Epidermis (Deep to Superficial) 1 Stratum Basale (Base Layer) | Single layer of column-shaped cells Only layer where cells divide (mitosis) New cells move upward to replace old ones Also called stratum germinativum |
| Stratum Basale (Base Layer) 2 Stratum Spinosum (Spiny Layer) | 8–10 layers of irregularly shaped cells Cells connected by desmosomes, giving a spiny appearance Rich in RNA, helping make keratin |
| Stratum Basale (Base Layer) 3 Stratum Granulosum (Granular Layer) | Cells are tightly packed and shaped like soap bubbles. They form tight junctions that make the skin waterproof. Cells begin to break down and fill with keratohyalin (a protein needed for keratin). |
| Stratum Basale (Base Layer) 3 Stratum Granulosum (Granular Layer) continue | Also produce glycophospholipids, which help seal the skin. In thin skin, this layer may be hard to see. |
| Stratum Basale (Base Layer) Stratum Lucidum (Clear Layer) | Found only in thick skin (palms and soles). Cells are flat, clear, and dying. Filled with eleidin, which turns into keratin. |
| Stratum Corneum (Horny Layer) | Top layer of the skin. Made of dead, flat cells full of keratin. Forms a strong, waterproof barrier. Cells are constantly shed and replaced. Helps protect against germs, chemicals, and physical damage. |
| Keratinization | The process where cells move up from deeper layers, fill with keratin, and die. Creates the skin’s outer protective barrier. |
| What Is the Dermis? | Also called the “true skin” Located beneath the epidermis |
| dermis Made of two layers: | Papillary layer (thin, top layer) Reticular layer (thicker, deeper layer) |
| Functions of the Dermis | Provides strength and protection from injury and pressure Stores water and electrolytes |
| dermis contains Helps regulate body temperature through its rich blood supply | erves and sensory receptors (for touch, pain, temperature) Hair follicles Sweat and oil glands Muscle fibers Blood and lymph vessels |
| Papillary Layer | Contains dermal papillae (tiny bumps that stick into the epidermis) Made of loose connective tissue with collagen and elastic fibers Increases surface area for better connection between skin layers |
| Dermal Ridges (Friction Ridges) | Formed by the epidermis following the shape of dermal papillae Create fingerprints and toe prints Help with: Gripping objects and surfaces Sensing textures |
| Melanin | Melanin is the pigment that gives skin its color. Made by melanocytes in the stratum basale of the epidermis. Everyone has about the same number of melanocytes—what differs is how much melanin they produce. |
| melanin 2Two Main Types: | Eumelanin – dark brown to black Found in dark skin and hair Absorbs UV radiation well Pheomelanin – reddish to orange Found in light skin, red hair, and freckles Less UV protection |
| How Melanin Is Made | Melanocytes convert tyrosine (an amino acid) into melanin using the enzyme tyrosinase. Melanin is packaged into melanosomes and sent to keratinocytes, forming a protective cap over their nuclei. This cap blocks UV rays from damaging DNA. |
| What Affects Melanin Production | Genetics: Genes control how much melanin is made. If tyrosinase is missing, albinism occurs (no pigment in skin, hair, or eyes). Sunlight: UV exposure increases melanin production (tanning). |
| What Affects Melanin Production | Hormones: Melanocortins (like α-MSH) trigger melanin production. Made by the pituitary gland and keratinocytes. Endothelin-1 (ET-1) also helps boost melanin. |
| What Affects Melanin Production | Age: Loss of melanocyte stem cells causes gray hair. UV damage over time can cause age spots. |
| function of the bones SUPPORT | SUPPORT Bones form the framework of the body Help with shape, alignment, and posture Held together by ligaments and muscles |
| function of the bones Protection | Bones shield vital organs Example: skull protects the brain, ribs protect the heart and lungs |
| function of the bones Movement | Bones and joints act as levers Muscles pull on bones to create movement |
| function of the bones Mineral Storage | Bones store calcium, phosphorus, and other minerals Help maintain blood calcium balance |
| function of the bones Hematopoiesis | Bones produce blood cells in red bone marrow Found in long bone ends, skull, pelvis, sternum, and ribs |
| Types of Bones by Shape | Long bones Longer than wide (e.g., femur) Short bones Cube-shaped (e.g., wrist bones) Flat bones Thin and flat (e.g., skull, ribs) Irregular bones Odd shapes (e.g., vertebrae) Sesamoid bones Small, round, in tendons (e.g., patella) |
| Bone Tissue Types 2 Most bones contain both types, in different amounts depending on their function. | Compact Bone: Dense and solid; provides strength. Cancellous Bone (also called spongy or trabecular bone): Has open spaces and a network of thin beams; lighter and helps absorb shock. |
| Parts of a Long Bone 1Diaphysis | Diaphysis The shaft or long middle part Made of compact bone Strong and lightweight for support |
| Parts of a Long Bone 2 Epiphyses The ends of the bone (top and bottom) | Bulb-shaped for joint stability and muscle attachment Filled with spongy (cancellous) bone and red marrow Growth happens at the epiphyseal plate (later becomes the epiphyseal line) The area between the shaft and ends is the metaphysis |
| Parts of a Long Bone3 Articular Cartilage | A smooth, cushiony layer of hyaline cartilage Covers the joint surfaces of the epiphyses Helps absorb shocks and reduce friction |
| Parts of a Long Bone4 Periosteum | A tough outer membrane covering the bone (except at joints) Contains blood vessels and bone cells Helps with bone growth, repair, and muscle attachment |
| Parts of a Long Bone 5 Medullary Cavity | A hollow space inside the diaphysis Filled with yellow marrow (fat storage) in adults |
| Parts of a Long Bone 6 Endosteum | A thin lining inside the medullary cavity and spongy bone spaces Contains bone cells and stem cells for growth and repair |
| 🦴 What Is Bone Tissue? Also called osseous tissue | A type of connective tissue made of: Cells Fibers (mostly collagen) Matrix (hard, calcified material) |
| Bone Matrix Composition 1Inorganic Salts (≈ 2/3 of matrix) Inorganic Salts (≈ 2/3 of matrix) Mostly hydroxyapatite crystals (85%) Also includes calcium carbonate, magnesium, sodium, sulfate, and fluoride | These minerals make bone hard and stress-resistant Harmful substances (like radioactive elements) can also build up in bone and cause disease |
| Bone Matrix Composition Organic Matrix (≈ 1/3 of matrix) | Made mostly of collagen fibers Provides flexibility and strength |
| Ground Substance in Bone | A gel-like material that helps support and connect bone cells and fibers Plays a key role in growth, repair, and remodeling |
| Ground Substance in Bone | Chondroitin sulfate: A protein that keeps cartilage elastic and compressible May help slow cartilage breakdown Glucosamine: An amino sugar that helps form, maintain, and repair cartilage |
| Microscopic Bone Structure | Circumferential lamellae: Layers of bone around the outer (periosteum) and inner (endosteum) edges Lacunae: Tiny spaces in the bone matrix that hold bone cells and tissue fluid |
| Microscopic Bone Structure | Canaliculi: Microscopic canals that connect lacunae to each other and to the central canal |
| Microscopic Bone Structure | Central Canal (Haversian Canal): Runs through the center of each osteon Contains blood vessels, lymph vessels, and nerves Supplies nutrients and oxygen to bone cells via canaliculi |
| Types of Bone Cells | Osteoblasts – Bone builders Make and release osteoid (soft bone matrix) Help form hydroxyapatite crystals to harden bone Come from stem cells in the endosteum and central canals |
| Types of Bone Cells Osteoclasts – Bone breakers | Osteoclasts – Bone breakers Large cells with many nuclei Break down bone using: Hydrochloric acid (HCl) – dissolves minerals Collagenase – breaks down collagen |
| Types of Bone | Recycle minerals and proteins back into the bloodstream Work in cycles with osteoblasts to remodel bone |
| Types of Bone CellsOsteocytes | Osteocytes – Bone maintainers Mature osteoblasts trapped in bone matrix Live in small spaces called lacunae Send out branches through canaliculi to share nutrients Help maintain bone and communicate with other cells |
| What Is Bone Marrow? | A soft connective tissue found in: Medullary cavities of long bones Spongy bone spaces Also called myeloid tissue Main job: make blood cells |
| 🔴 Red Marrow vs 🟡 Yellow Marrow | Type Description Red Marrow Found in infants and children; makes red blood cells Yellow Marrow Replaces red marrow with fat cells as we age; less active in blood cell production |
| 🔴 Red Marrow | In adults, red marrow remains in: Ribs Vertebrae Ends of humerus and femur Pelvis |
| 🟡 Yellow Marrow | Yellow marrow can turn back into red marrow during: Anemia Radiation exposure Certain diseases |
| What Is Osteogenesis? | The process of forming bone from cartilage or fibrous tissue Begins before birth Involves two key cell types: Osteoblasts – build bone Osteoclasts – break down bone |
| How Bones Form | Bones start as cartilage models These models are gradually replaced by calcified bone matrix The process of adding calcium salts makes bones hard Bone constantly remodels to adjust shape, size, and strength |
| What Is Intramembranous Ossification? | A process where flat bones (like the skull) form inside connective tissue membranes Begins when stem cells become osteoblasts (bone-forming cells) These cells group into ossification centers |
| Intramembranous Ossification How It Works | Osteoblasts make: Mucopolysaccharides (carbohydrates for ground substance) Collagen fibers (protein for structure) These materials form the organic bone matrix |
| Intramembranous Ossification How It Works | Calcification happens: Calcium salts are added to harden the matrix Trabeculae (tiny bone beams) form and connect to make spongy bone The spongy bone core (called diploe) gets covered by compact bone on both sides |
| Primary Joint Classifications | |
| How Joints Are Classified | By Structure (based on what connects the bones) Fibrous joints – bones joined by fibrous tissue Cartilaginous joints – bones joined by cartilage Synovial joints – bones separated by a fluid-filled capsule |
| How Joints Are Classified | By Function (based on movement allowed) Synarthroses – immovable joints Amphiarthroses – slightly movable joints Diarthroses – freely movable joints |
| Fibrous Joints (Synarthroses) | Bones fit closely together Joined by fibrous tissue Allow little or no movement |
| Types of Fibrous Joints: 1 | Syndesmoses Bones connected by ligaments Example: joint between radius and ulna Allows slight movement |
| Types of Fibrous Joints:2 | Sutures Found only in the skull Bones interlock like puzzle pieces Become fused with age |
| Types of Fibrous Joints: 3 | Gomphoses Joint between a tooth and its socket in the jaw Held by the periodontal membrane |
| What Are Cartilaginous Joints? | Bones are joined by cartilage (not fibrous tissue or fluid-filled capsules) Allow limited movement Important in areas like the pelvis during childbirth |
| Two Types of Cartilaginous Joints 1 | Synchondroses Bones joined by hyaline cartilage Examples: First rib and sternum Epiphyseal plate (growth plate) in growing bones Mostly found in children; many disappear as bones fuse |
| Two Types of Cartilaginous Joints 2 | Symphyses Bones joined by fibrocartilage Example: Pubic symphysis Slight movement helps with shock absorption and flexibility |
| Where Are Symphyses Found? | Mostly located along the midline of the body Common examples: Pubic symphysis (between hip bones) Intervertebral discs (between spine bones) |
| KNOW THIS | Intervertebral discs are made of tough fibrocartilage They allow limited spine movement and absorb impact The bodies of vertebrae form cartilaginous joints The articular facets between vertebrae are synovial joints (more on these later) |
| What Are Synovial Joints? | reely movable joints (also called diarthroses) Most common and complex joints in the body Found mostly in the appendicular skeleton (arms and legs) |
| Parts of a Synovial Joint | Joint Capsule A sleeve-like cover around the joint Connects and holds the bones together Synovial Membrane Lines the inside of the joint capsule Makes synovial fluid to lubricate and nourish the joint |
| Parts of a Synovial Joint | Articular Cartilage Smooth layer of hyaline cartilage Covers bone ends and cushions the joint Joint Cavity Small space between bones Allows free movement |
| Parts of a Synovial Joint | Menisci (Articular Disks) Pads of fibrocartilage in some joints (like the knee) Help divide the joint cavity and improve fit Ligaments Strong bands of fibrous tissue Help stabilize the joint even more than the capsule |
| Parts of a Synovial Joint | Bursae Small, fluid-filled sacs near joints Reduce friction and cushion tendons near bony areas (like knees and elbows) |
| Synovial joints are freely movable and grouped by how many directions (axes) they allow movement: | Uniaxial Joints Move in one direction (one axis) Hinge Joints Like a door hinge: move back and forth Examples: elbow, knee, finger joints |
| Pivot Joints | One bone rotates around another Examples: Neck (between first and second cervical vertebrae) Forearm (radius and ulna) |
| One bone rotates around another Examples: Biaxial Joints Move in two directions (two axes) | Saddle Joints Bone ends shaped like mini saddles Found only in thumbs Allow opposition (thumb touches fingertips) |
| Biaxial Joints Move in two directions (two axes) | Condyloid (Ellipsoidal) Joints Rounded bone end fits into an oval socket Examples: Base of fingers Wrist Skull and spine connection |
| Multiaxial Joints Move in three or more directions | Ball-and-Socket Joints Most movable type Ball-shaped bone fits into a cup-like socket Examples: shoulder, hip |
| Multiaxial Joints Move in three or more directions | Gliding Joints Flat surfaces slide past each other Allow limited movement Examples: joints between vertebrae |
| Types of Movement at Synovial Joints | Synovial joints allow free movement, depending on bone shape, ligaments, muscles, and tendons. Movements are grouped into: Angular Circular Gliding Special |
| Range of Motion (ROM) Measures how far a joint can move | Can be tested: Actively (person moves the joint) Passively (doctor moves the joint) A tool called a goniometer measures joint angles in degrees Helps assess injury, recovery, or joint health |
| Angular Movements Change the angle between bones:Flexion: | Flexion: Decreases the angle (bending) Example: bending your elbow or head forward |
| Angular Movements Change the angle between bones:Extension | Extension: Increases the angle (straightening) Example: straightening your arm or leg |
| Angular Movements Hyperextension Change the angle between bone | Hyperextension: Extending beyond normal range Example: bending the knee or shoulder too far back |
| Angular Movements plantar Flexion: | Plantar Flexion: Pointing the foot downward Increases angle between foot and leg |
| Angular Movements plantar Flexion: | Dorsiflexion: Lifting the foot upward Decreases angle between foot and leg |
| Angular Movements plantar Flexion: | Abduction: Moving a limb away from the body’s midline Example: lifting your arm or leg to the side |
| Angular Movements plantar Flexion: | Adduction: Moving a limb toward the body’s midline Example: bringing your arm or leg back in |
| Connective Tissue Layers in Muscle Muscles are wrapped in layers of connective tissue: | Layer Covers... Endomysium Each individual muscle fiber Perimysium A bundle of fibers (fascicle) Epimysium The entire muscle |
| Muscle Shapes and Fiber Arrangements Muscle strength and movement depend on fiber direction and shape. Common types include:1 | Parallel Muscles Long, strap-like fibers Example: sartorius, rectus abdominis |
| Muscle Shapes and Fiber Arrangements Muscle strength and movement depend on fiber direction and shape. Common types include 2 | Convergent Muscles Fibers spread out like a fan Example: pectoralis major |
| Muscle strength and movement depend on fiber direction and shape. Common types include 3 | Pennate Muscles (feather-like) Unipennate: fibers on one side (e.g., soleus) Bipennate: fibers on both sides (e.g., rectus femoris) Multipennate: many feather-like sections (e.g., deltoid) |
| Muscle strength and movement depend on fiber direction and shape. Common types include 4 | Fusiform Muscles Bulging center (“belly”) with tapered ends Example: brachioradialis |
| How Muscles Work Together | Muscles usually work in groups, not alone Some contract while others relax to create smooth movement Different roles help control and stabilize motion |
| Muscle Roles Prime Mover (Agonist) | Prime Mover (Agonist) The main muscle doing the movement Example: brachialis flexes the elbow |
| Muscle Roles Antagonist | Antagonist Does the opposite of the prime mover Relaxes while the prime mover works Helps with control and precision Example: triceps relax when biceps flex |
| Muscle Roles Synergist | Synergist Works with the prime mover Makes the movement stronger and smoother |
| Muscle Roles Fixator | Fixator Stabilizes joints during movement Helps maintain posture and balance A type of synergist |
| What Is a Lever System?A lever is a rigid bar that moves around a fulcrum (pivot point) | A lever is a rigid bar that moves around a fulcrum (pivot point) In the body: Bones = levers Joints = fulcrums Muscle contraction = force (pull) Body part or weight = load |
| Parts of a Lever System | Lever – the bone Fulcrum (F) – the joint Load (L) – the resistance or weight Pull (P) – the muscle force |
| Types of Levers in the Body | First-Class F between P and L Head tipping backward Stability Second-Class L between F and P Standing on toes, opening mouth Strength (less common) Third-Class P between F and L Flexing forearm at elbow Speed and range (most common) |
| Key Neck Muscles for Head Movement | Sternocleidomastoid Both sides contract → head bends forward (like in prayer) One side contracts → head turns to the opposite side Semispinalis Capitis Extends the head (tilts it backward) Also helps bend the head to the side |
| Key Neck Muscles for Head Movement | Splenius Capitis Both sides → pull head back upright One side → rotates and tilts head toward that side Longissimus Capitis Hidden under other muscles Both sides → extend the head One side → bends and rotates head toward that side |
| Main Thorax Muscles for Breathing | External Intercostals Located between ribs Lift the ribs during inhalation Help expand the chest |
| Main Thorax Muscles for Breathing | Internal Intercostals Also between ribs, but deeper Lower the ribs during exhalation Help push air out |
| Main Thorax Muscles for Breathing | Diaphragm Dome-shaped muscle under the lungs Flattens during inhalation, increasing chest space Allows air to enter the lungs |
| Extra Muscles for Deep Breathing | Used during exercise or heavy breathing: Sternocleidomastoid – lifts the upper chest Serratus Anterior – helps expand the rib cage Pectoralis Major – assists in pulling the chest upward |
| muscles of the abdominal wall:Structure of the Abdominal Wall | Made of three layers of muscles with fibers running in different directions (like plywood) This design creates a strong support system for the abdominal organs |
| Muscle Layers: | External Oblique Fibers run downward and inward Internal Oblique Fibers run almost at right angles to the external oblique Transversus Abdominis Fibers run side to side (transversely) |
| Rectus Abdominis | Long, strap-like muscle down the center of the abdomen Has three tendinous intersections (visible as “six-pack” lines) Covered by rectus sheaths formed from the aponeuroses of the other three muscles |
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