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THE MCAT BIO-7
MUSCLE, SKELETAL, AND IMMUNE SYSTEM
| Question | Answer |
|---|---|
| What is characteristic of osteoporosis? | decreased osteoblas and increased osteoclast activity |
| Skeletal muscle -striated? -number of nuclei -tire easily? | -striated -multiple nuclei -strong but tire easily |
| Smooth muscle -striated? -number of nuclei -tire easily? | -not striated -single nucleus per cell -weak but doesn't tire easily |
| Cardiac muscle -striated? -number of nuclei -tire easily? | -striated -single nucleus per cell -strong and doesn't tire easily |
| What attaches muscle to bone? | tendon |
| What is a ligament? | attaches bone to bone |
| What are antagonistic / agonistic muscles? | -agonist - contracts -antagonist - stretches |
| What are main functions of muscle contractions? | -generate mvmt -aid circulation -produce large amt of heat |
| sarcomere and what is it made of? | -basic fxnal unit of skeletal muscle -thick and thin filaments |
| myofibril | sarcomeres placed end to end |
| sarcoplasmic reticulum | muscle cell ER filled with Ca that surrounds myofibrils |
| sarcolemma | mem that wraps several myofibrils together to form muscle cell |
| myocyte | muscle cell |
| fasciculus | many myofibrils bound together to form a single muscle |
| What are thick and thin filaments made of? | -thick = myosin -thin = actin |
| Z-line | -sarcomere boundary -anchors thin filaments -creates striated look |
| M-line | runs down center of sarcomere |
| I-band | REgion with thin filaments only |
| H-zone | Region with thick filaments only |
| A-band | Contains all the filaments (thick and thin) where they overlap |
| What does not change during a muscle contraction? | A-band |
| What are 3 stages for contraction? | initiation, sarcomere shortening, relaxation |
| What ntm does nx release to activate muscle? | AcH |
| What are steps from nx to calcium release from Sarcoplasmic Reticulum? | nx --> muscle --> sarcolemma --> t-tubules --> SR |
| What is created to move muscle? | Action potential! |
| t-tubules | connected to sarcolemma to allow ions to uniformly flow and runs deep into cx |
| What two factors are attached to actin during contraction? | troponin and tropomyosin |
| ________ covers active site on actin to prevent myosin from binding | Tropomyosin |
| In presence of ______, _____ pulls tropomyosin back to expose active site for myosin. | -calcium -troponin |
| Myosin expels _________ and assumes lower energy position to drag actin with it. | phosphate and ADP |
| What powers the "power stroke"? | energy from ATPase activity in myosin head |
| What does the power stroke create? | shoretening of sarcomere |
| What releases myosin head from actin? | ATP |
| Before contraction, myosin is in _______ state with ________ attached | -high energy -phosphate and ADP |
| Why is calcium impt for muscle contraction? | myosin binding site will be covered by tropomyosin |
| What creates rigor mortis? | ATP is no longer produced --> myosin heads cannot detach from actin |
| Is ATP directly needed for powerstroke? | NO --> only needed for detachment of myosin head from actin |
| When myosin binds with actin, myosin expels ______ and assumes _____ energy position | -phosphate and ADP -lower |
| tetanus | contractions become so frequent that muscle has no time to relax --> fatigue |
| motor unit | single motor nx and all corresponding muscle fibers it innervates |
| Muscles with intricate mvmts have ____ motor units. | smaller |
| Myoglobin | stores oxygen inside muscle cx (only one O2) |
| slow oxidative red fibers (Type 1) and why are they slow? | high myoglobin and mitochondria --> split ATP at slow rate and slow to fatigue |
| Fast oxidative red fibers (Type IIA) and why are they fast? | -split ATP at a high rate -not as resistant to fatigue |
| Hemoglobin binds O2 tighter than myoglobin. | FALSE --> myoglobin binds tighter |
| Fast glycolytic white fibers (Type IIB) | -low myoglobin and high glycogen |
| Do white or red fibers require oxygen? | red |
| What is the muscle type for postural muscles? | Slow oxidative red fibers |
| What is the muscle type for upper leg muscles? | fast oxidative red fibers |
| What is the muscle type for upper arm muscles? | fast glycolytic white fibers |
| Does mitosis create new muscle cx? | NO |
| How does muscle cx grow? | -diameter of muscle increases, sarcomeres lengthen -number of sarcomeres and mito increase |
| Can you grow new muscle cx? | NO --> born with all of the muscle cx you will ever have |
| intercalated disks in cardiac muscle | -separate each cardiac muscle cx -contains gap jxns which spread AP via electrical synapse |
| How does cardiac muscle grow? | hypertrophy |
| Why does AP plateau after depol. in cardiac muscle? | slow voltage-gated Ca channels allow more Ca to enter and lengthen time of contraction |
| Does smooth muscle have sarcomere? | NO |
| Myogenic activity in smooth muscle | contracts without nervous system input --> pH, O2, CO2, temp |
| What nervous system does skeletal muscle belong to? | somatic nervous system |
| What nervous system does smooth and cardiac belong to? | autonomic nervous system |
| How does the body store energy in relation to creatine phosphate and ATP? | transfers phosphate from ATP to creatine to make Creatine-P |
| Why is creatine phosphate useful? | immediate creation of ATP without glycolysis or TCA cycle |
| What does creatine-P do? | transfers P to ADP |
| Muscles can only exert a pushing / pulling force? | pulling |
| How are relaxation and elongation different? | -all muscles can relax once myosin heads are unbound -not all muscles can elongate |
| What are flexors? | biceps and hamstrings |
| What are extensors? | triceps and quadriceps |
| What do flexors do? | decrease angle of joint btwn 2 bones |
| What do extensors do? | increase angle of joint btwn 2 bones |
| Contraction causes ____ out of 2 bones to move | one |
| What is the muscle called that is attached to stationary bone during mvmt? | origin |
| What is the muscle called that is attached to bone that moves? | insertion |
| Abductor / adductor? | -abductor = moves body away from body's midlline -adductor - moves part of body towards body's midline |
| What are some examples of connective tissue? | cartilage, bone, ligaments, tendons, fat, blood |
| What is characteristic of white muscle? | fast but tires easily |
| What is characteristic of red muscle? | high endurance but slow |
| Mito: white muscle vs. red muscle | white muscle has few mito while red muscle has a lot of mito |
| Myosin power stroke causes actin to move towards ____ line. | M line |
| How to detach myosin head from actin? | 1. ATP binding detaches myosin head 2. ATP hydrolysis is needed for de-powerstroke to unbend myosin head |
| ____ binds to troponin and troponin moves ______. | calcium and tropomyosin |
| terminal cisternae | enlarged areas of the SR surrounding the t-tubules that store calcium |
| Muscle contraction steps | nerve stimulates muscle, AP goes into muscle through t-tubules, stimulate SR to release calcium, actin-myosin action |
| squamous | flat |
| What are simple epithelium cx good for? | absorption, secretion, filtration, diffusion |
| What are stratified epithelium good for? | protection against abrasion |
| What are endothelial cells? | lines inside of organs and blood vessels --> aka simple squamous epithelium |
| What is connective tissue? | cx + extracx matrix |
| What is extracx matrix? | fibers (collagen) and glue to hold everything together |
| What do fibroblasts do? | make connective tissue (i.e. fats, tendons, ligaments) |
| What do chondroblasts make? | cartilage |
| What do hematopoietic stem cx make? | blood |
| "-blast" | stem cx actively producing matrix |
| "-cyte" | mature cx doing housekeeping |
| What is most common extracx fiber type? | collagen |
| What are the fiber types for connective tissue and what is each known for? | collagen (strong) elastic fibers (stretch) reticular fibers (branch and form nets) |
| What is loose connective tissue? | loose fibers with lots of fluff (fat) |
| What is dense connective tissue? | dense fibers with little fluff (tendon, ligament) |
| What is cartilage? | connective tissue made of chondrocytes + matrix --> no blood vessels |
| macrophages | phagocytize pathogen and then present antigen on cx |
| neutrophils | phagocytize pathogen and destroy it |
| mast cx | release histamine during allergy to bring inflammation |
| natural killer cx | kill infected / abnormal cx (esp. cancer cx) |
| dendritic cx | present antigen to T-cx during cell-mediated immunity |
| Where are all lymphocytes formed? | bone marrow |
| Where do T-cx mature? | thymus |
| Cytotoxic T-cx | recognize antigen on infected cx and signal for apoptosis |
| Helpter T-cx | recognize antigen and signal for activation of macrophages, T, and B-cx |
| B-cx form _____ and ______ when exposed to antigen. | plasma cx and memory cx |
| Plasma cx role in immune response. | secrete free antibody that can either act on its own or binds with mast cx and antigen |
| Memory cx role in immune response | stick around in case same antigen attacks in future |
| Where do b-cx differentiate? | bone marrow |
| ALL blood cx and immune cx arise from ? | bone marrow stem cx |
| What is role of spleen for WBC and RBC? | -site for WBC to reside and proliferate -removes old RBC and platelets -filters blood and removes foreign antigens |
| Interferons in immune response? | interfere with virus replication |
| Complement px in immune response? | punch holes in pathogen mem. |
| Why are WBCs recruited faster during a fever / inflammation? | WBC are more active at higher temperature |
| Immunity neutralization | pathogen can't adhere to host cx |
| Immunity opsonization | easier for phagocytosis |
| Complement activation | kills infected cx by punching holes in cx mem |
| What does the antibody consist of? | 2 light chains and 2 heavy chains linked by disulfide bonds |
| Hypervariable regions of antibody | tips of Y in antibody that are unique |
| Which T-cx are activated with an extracx pathogen? | helper T-cx --> activate macrophages and B-cx |
| Which T-cx are activated with an intracx pathogen? | cytotoxic T-cx |
| What creates inflammation? | histamine, prostaglandins, lymphokines |
| How do cx stop bacteria? | inflammation --> high temp stops bacteria growth |
| How do cx stop virus? | viral infected cx produce interferon to prevent viral replication |
| How do macrophages destroy cx material? | lysozymes |
| What do vaccinatins create? | development of lasting memory cells |
| Where do B-cx mature? | spleen and lymph nodes |
| How to antibodies fight infection? | -bind to foreign antigens and allow other immune cx to phagocytize -cause agglutination |
| What are plasma cx? | specialized B-cx that produce and secrete antibodies |
| Basic outline of humoral immunity | extracx microbe, B-cx secrete antibody, phagocytize |
| Antigen-binding region | specific polypeptide sequence that will bind ONE antigen |
| constant region | recruitment and binding of other immune modulators (i.e. macrophages) --> doesn't bind antigen |
| How long is primary immune response vs. secondary? | 20 vs. 5 |
| Humoral vs. cx-mediated immunity | -Humoral = extracx pathogen --> phagocytize -cx-mediated = pathogen that has invaded cx --> perforin |
| What type of cx does HIV affect? | helper T-Cx |
| What does helper T-cx secrete to coordinate immune response | interleukins aka lymphokines |
| What does helper T-cx recruit? | B-cx, killer T-cx, suppressor T-cx |
| How does killer T-cx kill viral-infected cx? | release perforin |
| Why are killer T-cx so effective? | release perforin so can attack many cx since don't phatocytize |
| Why is use of immunosuppressants necessary during cancer or after organ transplant? | killer T-cx will try to destroy implanted organ |
| epitope | specific part of antigen that is recognized by immune system aka antigenic determinant |
| Why do B-cx have more rough ER? | rough ER is responsible for production of secretory px |
| MHC Class I | px on every cx that presents to killer T-cx |
| MHC Class II | px on immune cx (macrophages) that present to helper T-cx |
| MHC Class I vs. MHC Class II in terms if type of response | MHC I - cx response MHC II - humoral response |
| What are antigens made of? | px and carbs on cx |
| What if immunity can't differentiate between self and non-self? | autoimmunity |
| What type of rxn are allergies? | hypersensitivity |
| Antigens stimulate B-cx to ______ while T-cx to _______. | -produce antibodies -kill directly |
| Type of pathogen: Cx-mediated vs. humoral | Cx-mediated = viral and fungal Humoral = bacterial |
| Type of passive immunization. | antibody transfer across placenta and breastmilk |
| Are antibodies used in cx-mediated response? | NO |
| Shape of skeletal, cardiac, and smooth muscle? | skeletal - non branched cardiac - branched smooth - tapered |
| What gives striated appearance? | presence of sarcomeres |
| A bands are (dark /light) and I bands are (dark / light) | -dark -light |
| Which types of muscles have sarcomeres? | skeletal and cardiac |
| What gives nonstriated appearance? | no sarcomeres |
| What do all muscles use in common? | myosin, actin, and sliding filament model |
| What do somatic motor nx control? | skeletal muscles |
| What do autonomic motor nx control? | involuntary muscles (smooth and cardiac) |
| Neuromuscular junction | nerve (axon terminal) meets muscle (motor end plate) |
| Motor end plate | sarcolemma that synapses with motor nx |
| Ultimately, what causes a muscle to contract? | AP |
| Both sympathetic and parasympathetic are motor nx that innervate ______ muscles | involuntary |
| During sympathetic response, pupils _____; parasympathetic, pupils _____. | dilate / constrict |
| What are main fxns of skeletal system? | -structure -calcium storage -physical protection |
| What are long bones and example? | shaped like a rod (i.e. arm, leg, finger) |
| What are short bones and example? | shaped like a cube (i.e. wrist, ankle) |
| What are flat bones and examples? | flat bones (i.e. sternum, shoulder, ribs, skull) |
| What are irregular bones and examples? | Weird shapes (vertebrae and hip) |
| What is a joint? | bone meets bone --> can be mobile or non-mobile |
| Mobile joints vs. non-mobile joints | -have synovial fluid cavity to lubrication -connect bone to bone with cartilage or fibers |
| Ball and socket joint example | shoulder or hip |
| Hinge joint | elbow |
| Gliding joint | wrist |
| Immobile joint | skull and rib to sternum |
| Where is cartilage found? | ear, nose, epiglottis, ends of bones in joints, knee, btwn vertebrae |
| What are bone cells? | osteocytes |
| What is the extracx matrix of bone made of? | calcium-px matrix --> calcium, collagen, glue |
| What is membrane outside of bone called? | periosteum |
| Growth in length: osteoblasts vs. osteoclasts | osteoblasts lengthen and osteoclasts shape |
| Growth in diameter: osteoblasts vs. osteoclasts | osteoblasts widen and osteoclasts remove bone tissue from inside to keep bones light |
| Osteoblasts vs. osteocytes | -osteoblasts = stem cx that give rise to osteocytes -osteocytes = mature bone cx that build bone |
| What does bone marrow store? | blood stem cx and adipocytes |
| perichondrium | connective tissue that surrounds cartilage of developing bone |
| What is synovial fluid? | lubrication and has phagocytes |
| axial vs. appendicular | axial (spine) vs. appendicular (arms) |
| Endochondral ossification | cartilage template replaced by bone |
| Diaphyses | cylindrical shafts with marrow |
| Epiphyses | dilated ends made of spongy bone and compact bone |
| epiphyseal plate | site of longitudinal bone growth |
| Bone is storage site for ____ and_____ to maintain mineral homeostasis. | calcium and phosphate |
| hydroxyapatite crystals | calcium, phosphate, and hydroxide ions --> strength and mineral storage |
| How are osteocytes formed? | osteoblasts trapped btwn lamellae |
| osteon | cylinders in bone with blood vessel and nerve --> includes lamellae and haversian canal |
| What kind of marrow does spongy bone have? Compact bone? | -spongy bone = red and yellow marrow -compact bone = yellow marrow |
| What is main fxn of osteocytes? | exchange nutrients and waste with blood --> can also build bone |
| What materials are necessary to build bone? | collagen and inorganic ions |
| What must be released to move any voluntary muscle? | AcH |
| What is the pH of skin? | 5.6 |
| What allows macrophage to engulf microbe? | actin |
| During any infection, the first response is initiated from? | innate immunity |
| How does macrophage destroy contents? | Creates a phagosome and fuses with a lysosome to form a phagolysosome |
| What is the first line of immune defense? | skin, mucous, etc. |
| What is the second line of immune defense for innate immunity? | macrophages |
| What do helper T-cx release to active B-cx or T-cx? | interleukins |
| Do antibodies destroy foreign antigens? | NO --> recognize and identify them |
| Why does immune system normally avoid attacking it's own cells? | suppresses cells specific to body's own antigen s |
| Where are antigens carried? | on cx surface --> NOT on DNA, RNA, chromo |
| How do antibiotics work (2)? | -kill bacteria -stop bacteria from multipling |
| Where do leukocytes gravitate to? | inflammation |
| What are the causes of cancer? | -DNA damage -uncontrolled cx division |
| Relate striated muscle, KE, and PE. | striated muscle turns PE stored in glucose to KE of muscle contraction |
| Do antibiotics cause mutations? | NO |
| What do lymphocytes differentiate into? | T-cells and B-cells |
| Osteoblasts are eventually converted into/ | osteocytes |
| What do osteocytes do? | maintain healthy bone tissue during times of non-synthesis |
| Do osteoblasts divide? | NO |
| How do osteoclasts cause bone resorption? | use carbonic anhydrase to release HCl |
| Cardiac and smooth muscles depend on what type of junction? | gap junction --> skeletal can contract independently and do NOT rely on gap junctions |
| What are cardiac muscle cell gap junctions known as? | intercalated disks |
| How do smooth muscles differ from skeletal muscles? | no T-tutubles, no striations, no troponin, no tropomyosin --> myosin and actin filaments are present |
| What are the 2 locations for amylase? | mouth and s. intestine |
| Does Vitamin D increase / decrease blood calcium? | increases |
| What is the largest solid organ in the body? | liver |
| What are mature osteoblasts called? | osteocytes |
| What is the ntm used by parasympathetic to decrease heart rate? Increase heart rate? | acetylcholine / norepinehrine |
| Where does calcium for muscle contraction come from? | extracx environment and sarcoplasmic reticulum |
| lamellar bone vs. woven bone | -woven bone = immature -lamellar bone = strong and mature |
| What are types of lamellar bone? | spongy and compact |
| All muscle stimulating neurons produce what ntm? | acetylcholine |
| In a muscle contraction, which bands become smaller? | H and I |
| Where does Krebs occur? | mito |
| Red vs. white fibers | -red = slow contraction, full of mito -white = fast contraction, no mito (glycolysis) |
| What are myoblasts? | precursors to muscle skeletal cells |
| Marcrophages are part of what immunity? | innate, nonspecific immunity |
| What cx type gives rise to macrophages? | monocytes |
| How are plasma cells formed? | B-cx formed by bone marrow are converted into plasma cx during active infection |
| What do antibodies do? | bind invading bacteria to make them easier to be ingested by phagocytes |
| Does cx-mediated response involve antibodies? | NO |
| What are the body's 2 methods for regulating homeostasis? | endocrine and nervous system |
| Innate vs. humoral immune response | -innate = macrophages, neutrophils, natural killer cx -humoral immunity - B-cx |
| Why are helper T-cx so important? | control immune response to every antigen -without T-cx --> no immune response -macrophages and other nonspecific immune cx find foreign antigens and show them to helper T-cx (decide whether or not to mount response) |
| T/F: An antigen is digested by the lysosome before being presented to T-lymphocyte | TRUE |
| What is inflammation? | white blood cell (leukocyte) response to a bacterial infection --> increased vascular permeability |
| leukocyte vs. lymphocyte | -leukocyte = white blood cx -lymphoctye = special type of white blood cx -T and B-cx |
| What are the 2 subdivisions of acquired immunity? | cell-mediated and humoral immunity |
| Does parasympathetic / sympathetic innervation determine cardiac baseline? | parasympathetic |
| What is the pH of skin? | 5.6 |
| What is the first line of defense and second line of defense in innate immunity? | -skin, mucus, cilia -macrophages |
| basophils | inflammatory reactions esp. those involved with asthma and allergies |
| What is cell-mediated immunity most effective against? | virus-infected cells, microbes that survive phagocytosis, microbes that infect non-phagocytic cell |
| Cytokines | cell-signaling communication molecules used during immune response |
| T-cx mark invaders for destruction by? | macrophages |
| Is gray matter / white matter myelinated? | -gray matter - unmyelinated -white matter -myelinated |
| What type of cell myelinates central nervous system? | oligodendrocytes |
| What type of cell myelinates peripheral nervous system | Schwann cells |
| muscarinic rx are found in? nicotinic are found in? | CNS / NS |
| What type of channels are found at axon terminal? | calcium |
| Where is the greatest conc. of sodium channels found? | nodes of Ranvier |
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