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Biology
Nerve & Muscles
| Question | Answer | Answer pt.2 |
|---|---|---|
| The digestive system is formed by what? | It is formed by an alimentary canal (gastrointestinal tube) which begins @ the mouth & ends @ the anus | |
| What is the coelom & what does it do? | -It is a body cavity that the digestive system is suspended w/in -The coelom is separated into the thoracic cavity (upper) & the abdominal cavity (lower) | |
| The two cavities of the digestive systems are separated by what skeletal muscle? | It is separated by the diaphram | |
| What are the different kinds of epithelial cells? | -simple epithelium: consisting of a single layer of cells -stratified epithelium: consisting of two or more layers of cells | |
| Define microvilli | They are projections & they can ↑ the total absorptive area of the cell | |
| What are tight junctions? | -Acts as a permeability barrier -It prevents the transport of protein molecules from the lumenial side of the cell towards the basolateral side -Also acts as a glue holding neighboring cells together | |
| What are desmosomes? | Acts as dots of glue holding the epithelial cells together | |
| What is the basal lamina (basement membrane)? | -It is in close contact w/connective tissue that helps to anchor the cells in place -Is a type of desmosome | |
| What are gap junctions? | It provides a mean for water-soluble molecules to pass from the cytoplasm of one cell to the cytoplasm of another cell | |
| Define exocrine gland | It is when a cell secretes a substance into the lumen by way of a duct | |
| Define endocrine glands | It is when a cell secretes substances into the blood | |
| What is the difference between keratinized & non-keratinized epithelial cells? | -Keratinized: contains protein keratin. It generates dry, rough outer layer similar to human sky. Waterproof barrier -Non-keratinized: lacks keratin, leaving a wet, porous surface | |
| Your skin is composed of what kind of epithelial cells? | -Many layers of stratified squamous cells -Outer cells of skin = dead & they contain larger amount of keratin | |
| What are erector muscles? | It surrounds the hair follicles & it acts to straighten the hair shaft | |
| What are the different types of connective tissues? | Structural, blood cells, mast cells, adipose cells, & melanocytes | |
| Many proteins that make up structural connective tissue are secreted by what cells? | -Fibroblasts -Collagen -Reticulin -Elastin | |
| Define collagen | -It is a triple-stranded, insoluble, fibrous protein that is highly cross-linked (makes it strong & flexible) -Most abundant protein found in mammals | |
| Define reticulin | It is a thin fiber found in the spleen & lymph nodes. It is not as highly coiled as collagen | |
| Define elastin | It is a highly cross-linked protein found associated w/organs that require some degree of elasticity EX: skin, lungs, & blood vessels | |
| What's cartilage? | -It is another type of structural connective tissue which is secreted by a specialized fibroblast cell called chondrocyte -It is generally found in places where there is a certain amount of stress placed on the body | |
| Collagen found in the bone matrix is secreted by what cell? | It is secreted by a specialized fibroblast cell called osteoblast | |
| Organic & inorganic materials do what to the bones? | -Organic materials such as collagen lends flexibility to bone -Inorganic materials (crystals) lend rigidity | |
| The bone is also structural connective tissue. Where does it's weight come from? | 1/3 of weight = organic materials (collagen) 2/3 of weight = inorganic materials (calcium phosphate & calcium carbonate) | |
| Where can mast cells be found & what do they release? | - It can be found in the respiratory tract & gastrointestinal tract -It releases histamines in response to an allergic reaction | |
| Define adipose cells & melanocytes | -Adipose cells: cells that store fat -Melanocytes: cells that store pigments | |
| What are the components of a neuron? | -Cell body: involved in integration of info -Dendrites: involved in receiving & transmitting info towards the cell body -Axon: involved in conducting info away from the cell body | |
| What is the junction between two cells called? | A synapse | |
| What's the end of an axon called? | A synaptic bulb or bouton terminal | |
| What is the concentrations of K+, Na+, Cl-, & HCO3- inside and outside the cell? | INSIDE CELL: K+= 120-140 mM; Na+ = 10mM- 15mM; Cl- = 5-40 mM; HCO3- = 12-25 mM OUTSIDE CELL: K+= 5mM; Na+ = 150mM; Cl- = 130 mM; HCO3- = 25mM | |
| What is happening when a nerve is resting? | -The P (permeability) of K+>>>PNa+ b/c [K+] is higher inside the cell than outside. K+ will diffuse down its concentration gradient & leave the cell | -Due to diffusion being stranger than the electrical force, some K+ leak out the cell as well as Na+. To help this there is ATPase pump. It's responsible for asymmetrical gradient |
| What is happening when a nerve is stimulated? | PNa+ >> PK+, since [Na+] is higher outside the cell than inside. Na+ will tend to diffuse down its concentration gradient & into the cell | |
| What is propagation of an action potential? | It is the process of spreading an action potential along the length of a neuron's axon | |
| What are myelinated nerves? | -It's a nerve surrounded w/myelin which greatly↑ the rate @ which action potential is conducted | -A cell called glial attaches itself to a section of unmyelinated axon begins to rotate itself around the axon a # of times. During this process a myelin sheath is deposited on the axon |
| Define nodes of ranvier | It is where the deposition of myelin a long the axon is interrupted by areas where there is no myelin | |
| Define saltatory conduction | It is when the nerve impulse seems to jump from node to node along the axon | |
| Does unmyelinated or myelinated nerve increase the rate at which info is conducted? | Myelinated nerves | |
| Can ions transfer across the plasma membrane w/a myelin sheath present? | -No, it won't work b/c myelin sheath acts like a electrical insulator -Ions can only pass through the nodes of ranvier, therefore the action potential only occurs @ the nodes of ranvier as well | |
| What are the components of the end of an axon? | -Terminal bouton: can synapse on another axon of a different neuron, on a dendrite, or even on some type of cell body -Synaptic cleft: the space between the synaptic junction Pre-synaptic membrane: the membrane @ the terminal bouton | -Post-synaptic membrane: the plasma membrane that the synapse is being made to -Synaptic vesicles: It's w/in the terminal bouton. Each vesicles contains hundreds of thousands acetylcholine (ACh) |
| How does Ca^2+ channels play a role in neuromuscular junction? | -When an action protentional reacts w/the terminal bouton, it triggers the release of Ca^2+ in the synaptic vesicles making the vesicles fuse w/the pre-synaptic membrane. Releasing ACh into the synaptic cleft -This process is vis exocytosis | -Ca^2+ is then pumped out the cytosol and back into the extracellular fluid |
| What happens to the membrane of the synaptic vesicles that fused w/the presynaptic membrane? | They are recycled via endocytosis | |
| What is acetylcholinesterase? | -It is an enzyme bounded to the surface of the postsynaptic membrane -It hydrolyzes acetylcholine into acetate and choline. They are recycled back into the synaptic vesicle | |
| What happens at the postsynaptic membrane? | -ACh bind to the membrane causing a conformational change from a receptor to an ion channel. It allows Na+ to go through -Not voltage- activated, but ligand-activated | -Na+ enters post-synaptic membrane -> muscle fiber depolarize -> action potential eventually generated |
| What are the different kinds of potentials in the neuromuscular junction? | -Excitatory postsynaptic potential (EPSPs) : generates action potential, ↑ of Na+ which causes depolarization -Inhibitory postsynaptic potential (IPSPs): No action potential, ↑ K+ and Cl- which causes hyperpolarization | |
| What happens if two action potentials are coming towards one another? | When the two action potentials meet one another they will stop their propagation along the axon | |
| Explain the components of myofibrils | -Myofibrils contain contractile units. Each contractile is separated by a structure called z-line -Sarcomere: it is everything between one z-line to another z-line -A-band: it comprises of the thick contractile myosin | -I-band: just the thin actin (thin contractile protein) filament (crosses over the z-line) -H-band: region in center of the A-band and between the ends of the actin filaments |
| How is actin attached in the myofibrils? | Actin are attached to the z-lines | |
| How does actin interact with myosin? | They interact with each other through projections stemming from the myosin filaments (sometimes referred as myosin heads) | |
| What is actin composed of ? | It is composed of a protein subunit called G actin (globular). Each filament is composed of two rows of G actin monomers would around each other to form a helix | |
| Define tropomyosin | -It resides in the actin groove, it covers up the bonding sites for the myosin heads & prevents those head groups from attaching to the actin filament -When tropomyosin is covering the myosin heads, the muscle are in a state of relaxation | |
| What are the regulations of muscle contraction called for skeletal muscle and cardiac/smooth muscle? | -Skeletal muscle = actin-based regulation -Cardiac/smooth muscle = myosin-based regulation | |
| What is troponin? | -It is a multi-subunit binding protein interacts w/tropomyosin, actin, and Ca^2+ -When Ca^2+ binds to the troponin protein complex it causes tropomyosin to shift exposing the myosin heads which can now bind to the actin and muscle contractions follow | |
| What is surrounding each myofibril? | -The structure directly surrounding the myofibril is called the sarcoplasmic reticulum. It is a modified version of the ER. There is Ca^2+ w/in the membranous structure | -Surrounding the myofibril and sarcoplasmic reticulum is the sarcolemma (plasma membrane) w/the transverse tubule (t-tubules) attaches on the inside of the membrane t-tubules follow the z-lines of each myofibril |
| How does the action potential flow through the muscle? | When the action potential reaches the last junction it goes down each t-tubule and it somehow triggers the release of Ca^2+ from the sarcoplasmic reticulum (SA). The Ca^2+ goes from high concentration (SA) to low low concentrations (the cytosol). | It then binds to the troponin complex. Each sarcomere contracts simultaneously |
| What happens to the Ca^2+ after the nerve impulse stops? | It is pumped back into the sarcoplasmic reticulum by a Ca^2+- ATPase pump | |
| What are the different ways that the strength of muscle contraction can be varied? | 1) The size of the motor unit 2) The # of available motor units 3) The amount of actin and myosin contained w/each cell | |
| Define motor unit | It is a motor neuron and the muscle fibers that it innervates | |
| Define motor neuron | It is nerve cells whose cell bodies are located in the CNS and whose myelinated axons innervate (supple and organ or body parts w/nerves) skeletal muscle | |
| Define ganglion | It is the grouping of nerve cells | |
| What are the 3 basic anatomical divisions of the vertebrate brain? | 1) Forebrain (prosencephalon) 2) Midbrain (mesencephalon) 3) Hindbrain (rhombencephalon) | |
| Define efferent (motor) neuron | It is when a neuron carries the info AWAY from the brain or spinal cord | |
| Define afferent (sensory) neuron | It is when a neuron carries info INTO the spinal cord and brain | |
| What are the anatomical subdivisions of the forebrain? | -Cerebrum -Thalamus -Hypothalamus | |
| How is the cerebral hemisphere divided? | -Frontal lobe: associated w/movement and personality -Parietal: associated w/touch and stretch sensation -Occipital: associated w/vision -Temporal: associated w/hearing | |
| What is the outer most layer of the cerebrum called? | The cerebral cortex | |
| What is grey and white matter? | -Grey: it is simply nerve cell bodies and their dendrites -White: it is myelinated axons of the nerve cells -In spinal cord it's the opposite. Grey matter is more centralized, while white matter is more peripheral -Under grey matter is white matter | |
| What is the central sulcus? | It is a prominent groove that separates the frontal lobes and the parietal lobes | |
| What does the thalamus, hypothalamus, and pituitary gland do? | -Thalamus: relay station for much of the visual and auditory info received from the environment -Hypothalamus: it's concerned w/visceral activities of the body | -Pituitary gland: master endocrine gland of the body. It receives info from the hypothalamus & sends out info to regulate different parts of the body |
| Th brainstem contains what anatomical features? | -Midbrain: detects movement, direct eyes & head towards movement, & sense pleasure & pain -Cerebellum: responsible for bulk of regulation & coordination of muscular activity -Pons & medulla: coordinate visceral activities | -Reticular formation: core of brainstem; system designed to alert the brain. Also inhibits motor and sensory impulses and can induce sleep -Below medulla = spinal cord |
| What is homunculus? | -It is a schematic model of a human being mapped out on the sensory cortex -Made by a Canadian neurosurgeon | |
| Define monosynaptic reflex arc | -It is a reflex arc that provides direct communication between sensory and motor neurons innervating the muscle -Makes just one synaptic connection | |
| Define polysynaptic reflex arc | -Communication between afferent and efferent neurons is indirect and widely spread -It makes @ least two synaptic connections (can be more than two, but not less) | |
| Break down the efferent division | Efferent division -> autonomic nervous system -> sympathetic or parasympathetic nervous system | |
| Where are the nerve fibers located in the parasympathetic division? | The nerve fibers leave from the sacral portion of the spinal cord and from the midbrain (mesencephalon) and medulla (part of the rhombencephalon) | |
| What does the parasympathetic division do in the body? | - ↑ rate of digestion, ↓ heart rate, ↓ blood pressure, and pupils constrict (black part looks very small) -Rest and digest | |
| What are the similarities and differences between pre/post ganglionic nerve fibers in the parasympathetic division? | Diff: -Pre: found in sacral region of spinal cord and in the brainstem; nerve fiber = long -post: begins in & travels from the ganglion to the smooth muscle or gland being innervated; nerve fibers = short | Sim: Both release acetylcholine as the neurotransmitter |
| Define cholinergic | It is nerve fibers that release acetylcholine as a neurotransmitter | |
| What is the most prominent nerve in the parasympathetic divison? | -Vagus nerve -Roughly 3/4 of all neurons in division can be found on this nerve -It innervates many major organs (heart, lungs, etc) | |
| The sympathetic division of the autonomic nervous system has nerve fibers branching off from where? | It has nerve fibers branching off from the thoracic & lumbar regions of the spinal cord (middle of spinal cord) | |
| What are some charcteristics of the sympathetic division? | - ↑ heart rate, ↑ blood pressure, ↓ digestive functions, & pupils dilate (black part looks very big) -Fight or flight | |
| What are the different ways the preganglionic nerve fibers on the sympathetic division can get to all of the necessary organs? | (1) pass through this collection of ganglia to synapse w/other ganglia outside the sympathetic trunk (2) Pass into the sympathetic trunk & ascend or descend to synapse w/ganglia to other levels | (3) pass into the sympathetic trunk & directly synapse w/ a given ganglion |
| What are the similarities & differences between pre/post ganglionic nerve fibers in the sympathetic division? | Diff- Pre: Nerve fibers = short & neurotransmitter = ACh Post: nerve fibers = long & neurotransmitter = norepinephrine | |
| Define adrenergic | It is nerve fibers that release norepinephrine or epinephrine (adrenaline) as a neurotransmitters | |
| Define sympathetic trunk | -The sympathetic nerves that leave the thoracic & lumbar regions of the spinal cord first enter chains of ganglia connected by nerve fibers on either side of the spinal column -It is the chain of ganglia mentioned above | |
| In the sympathetic division, there is one long preganglionic nerve fiber. Where is that long fiber? | -This one long preganglionic nerve fiber goes to the adrenal medulla | |
| What is the adrenal medulla? | -The adrenal medulla is a region w/in the adrena gland located on the superior surface of the kidneys | |
| What happens when the adrenal medulla is stimulated? | -Norepinephrine (minor) & epinephrine (major) are released into the bloodstream (these are called hormones b/c they're released in the bloodstream; not a neurotransmitter) -Considered an endocrine gland -↑ Heart rate & pupils dilate | -Release of ACh (a neurotransmitter) triggers the release of the two hormones |
| How does the somatic nervous system work? | -Once the nerve fiber leaves the CNS, they do not make a synapse until they have reached their effector organ -When the synapse is made @ the effector organ, the neurotransmitter that is released is ACh -The somatic NS innervates skeletal muscle | -Innervation of the skeletal system muscle leads to excitation of the muscle itself |
| Define thermorecptors | Detects cold & warmth | |
| Define chemoreceptors | Detects taste, smell, oxygen, carbon dioxide, hydrogen ions, & blood glucose levels | |
| Define photoreceptors | W/in the retina of the eye can respond to the presence of a single photon of light | |
| Define a pacinian corpuscle | It has an unmyelinated nerve ending which is encapsulated in layers of connective tissue. However, the afferent nerve that leaves this encapsulated ending is myelinated | |
| What is the basic principle that all receptors follow? | -The amplitude (height) does not change, but the frequency changes -It is the frequency of action potentials that signals to the CNS the magnitude of the stimulus being received | |
| Define mechanoreceptors | They respond to a change in their configuration such as pressure, hearing, balance, & blood pressure | |
| What are nociceptors? | They're receptors that sense pain | |
| Define lateral inhibition | It is a phenomenon in which a neuron's response to a stimulus is inhibited by the excitation of a neighboring neuron | |
| What is the general rule for the 3 neurons involved in sensory pathway in the brain? | -First order: Neurons carrying info from the receptive field(s) enters the spinal cord & synapse w/second- order neurons -Second order: They ascend on the opposite side of the spinal cord to the thalamus | -Third order: neurons continue to ascend, until they reach a specific region of the somatosensory cortex of the cerebral hemisphere opposite to the side of the body in which the sensation was perceived |
| The troponin complex (Troponin I,C, and T) is required for muscle contraction in what kind of muscle? | Skeletal and Cardiac |
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Gabbgabb04
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