BIOL 312, Week 6-9 Notes
BIOL 312, Week 6-9 Notes BIOL 312
Edinboro University of Pennsylvania
Popular in Human Physiology & Anatomy I
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This 11 page Class Notes was uploaded by Caitlyn Wiercioch on Sunday August 21, 2016. The Class Notes belongs to BIOL 312 at Edinboro University of Pennsylvania taught by Matthew J. Foradori in Fall 2016. Since its upload, it has received 6 views.
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Date Created: 08/21/16
Anatomy and Physiology Exam 2 Notes Chapter 10 & 11: Muscle Contraction and Neural Functions: 1. Motion 2. Maintain Posture 3. Produce Heat Characteristics: 1. Excitable- responds to stimulation 2. Contractility- shortens 3. Extensibility- lengthens 4. Elastic- back to original shape 3 Types: Skeletal, Cardiac, & Smooth I. Skeletal Muscle A. Structure a. Fascia- thin sheet of C.T. beneath skin or around muscle and organs b. Epimysium- fibrous C.T. wraps entire muscle c. Perimysium- invagination of (b), divides muscle into bundles of fibers (cell) = fascicles d. Endomysium- invaginations of (c), divides fascicles into individual fibers B. Muscle Fiber Histology a. Sarcolemma- cell membrane of a muscle cell b. Sarcoplasm- cytoplasm c. Sarcoplasmic Reticulum- SER- runs through sarcoplasm d. Mitochondria- numerous e. T Tubules i. Invaginations of sarcolemma that run parallel to sarcoplasmic reticulum ii. Triad = 1 T Tubule and 2 sarcoplasmic reticulum (1 on each side) f. Myofibrils- threads running longitudinally through the fiber (#700-7000) composed of thin to thick myofilaments g. Myofilaments i. Thin Myofilament- composed of actin, troponin, & tropomyosin (proteins) ii. Thick Myofilaments 1. Made of Myosin 2. Round head & rod-shaped body (protein) 3. Head forms projections = cross bridges h. Sarcomere i. Stacked compartments of myofilaments ii. Separated from each other by Z lines (narrow zones of dense material) iii. Only (1) sarcomere goes from Z line to Z line iv. Each sarcomere approx. 2.6 um long v. A Band 1. In relaxed muscle, thin and thick overlap: form a dark, dense anisotropic band 2. Approx. .6 um vi. I Band 1. A light, less dense isotropic band is made up on thin myofilament 2. Approx. 1.0 um on each side vii. H Zone “Heavy” 1. Only thick myofilaments in A Band 2. M Line passes through the middle C. Contraction: sliding-filament theory of muscle contraction a. Basic Physiology i. Thin myofilament slide inwards toward H Zone ii. Cross bridges of thick myofilament connect w/ actin on thin myofilament iii. Thin and thick myofilament slide past each other iv. H Zone narrows and disappears v. Z Lines are moved towards A Band and sarcomere shortens vi. Muscle fiber shortens b. Anatomy i. Motor unit- motor neuron and muscle it stimulates ii. Myoneural junction- contact area b/w neuron & muscle iii. Motor endplate- sarcolemma in contact with axon iv. Motor unit # 1. Precise movement- 10 fibers/neuron (eye) 2. Gross movement- 500 fibers/neuron (biceps) v. Recruitment- increasing # of motor units active to complete work D.Contraction Physiology (https://www.youtube.com/watch? v=Cjx3vSm54N8) a. Nerve impulse -> synaptic vesicles -> release Acetylcholine b. Acetylcholine crosses myoneural junction and initiate an impulse spreading from motor endplate over sarcolemma c. Impulse enters T-Tubule and sarcoplasmic reticulum; Ca++ is released d. Ca++ activates myosin, which breaks down ATP e. Ca++ also bind the tropomyosin-troponin complex which permits the complex to split from thin myofilaments f. Free receptors sites on actin attach to myosin cross bridges, using energy from ATP breakdown; thin myofilaments slide past thick myofilaments g. Sliding draws the Z line closer, sarcomere shortens, fibers contract, muscle contracts h. Acetylcholinesterase degrades Ach; inhibits impulse i. Ca++ are actively transferred back into sarcoplasmic reticulum, ATP used j. Decrease Ca++ inactivates myosin, ADP -> ATP; ATP binds to myosin cross bridges k. Tropomyosin-troponin complex reattaches to actin l. Myosin cross-bridges separate from actin and thin myofilament return to relaxed state m. Sarcomere return to resting state, fibers relax, muscle relax E. Energy for Contraction a. Primarily ATP i. Excess stored in thick myofilaments ii. ATP needed for contraction (move cross-bridges) and relaxation (pumping Ca++ into sarcoplasmic reticulum) iii. Rigor Mortis- lack of ATP; cross bridges remain attached, no relaxation b. Secondary: Creatine Phosphate (C.P.) i. ATP + Creatine -> C.P. + ADP ii. Formed in liver iii. C.P. stored in muscle iv. Under strenuous exercise, C.P. + ADP -> ATP + creatine (anaerobic reaction) v. C.P. formation regulated by creatine kinase 1. Muscular dystrophy- increased skeletal creatine kinase blood levels 2. Myocardial infarction- increased cardiac creatine kinase blood levels vi. 3x more CP than ATP in skeletal muscle vii. Mechanical efficiency = 24% of energy to slide filaments 1. 76% lost as heat 2. Top athletes = 30% c. All or None Principle i. Muscle fibers will completely contract or not at all ii. Muscles have graded contraction due to recruitment F. Types of Contractions a. Twitch i. Rapid, jerky response to 1 stimulus ii. Divided into: 1. Latent period a. Approx. 10 msec b. After stimulus & before contraction 2. Contraction period = 40 msec 3. Relaxation period = 50 msec iii. Refractory Period nd 1. Time after contraction when a 2 stimulus will not result in a contraction 2. Skeletal muscle = 5 msec 3. Cardiac muscle = 300 msec b. Treppe AKA “Staircase effect” i. Muscle increase strength of contraction in response to same stimulus “warming up” ii. Primarily due to Ca++ relieving tropomyosin- troponin inhibition more efficiently c. Tetanus i. 2ndstimulus applied after 1 refractory period ii. A 2d contraction will be stronger than the 1 st iii. AKA. Summation of twitches iv. 2 types: 1. Incomplete (unfused) tetanus- muscle partially relaxed b/w contractions 2. Complete (fused) tetanus- continued contractions, no relaxation due to increasing stimulus rate d. Isotonic- muscle shortens, tension=constant e. Isometric- muscle remains same length, tension will increase G.Muscle Tone= a state of partial contraction; maintain posture a. Conditions: i. Flaccid: decrease in muscle tone ii. Atrophy: decrease in muscle fiber size and # of myofibrils due to lack of impulses, “wasting away” iii. Hypertrophy: reverse of atrophy; body builders b. Fibers i. Fast (white) twitch fibers 1. More extensive sarcoplasmic reticulum 2. Quick release & uptake of Ca++, faster contraction 3. Ex. Eye muscles = 1/100 second 4. Lack myoglobin: “white” 5. Anaerobic Respiration ii. Slow (red) twitch fibers 1. Slow contractions 2. Ex. Gastrocnemius = 1/30 sec 3. Using myoglobin: “red” 4. Aerobic respiration H. Control of Skeletal Muscle a. Neural Control i. Golgi Tendon Organs- provide sensory information on muscle tension ii. Muscle Spindle Apparatus- provides information on muscle length iii. Each spindle contains several thin muscle fibers= intrafusal fibers iv. Externa fibers= “extrafusal fibers” v. Spindles insert into tendons vi. Alpha motorneurons 1. Large, fast-conducting (=75 m/sec) neurons 2. Innervate extrafusal fibers 3. Stimulation results in contraction vii. Gamma Motorneurons 1. Thin, slow (=25 m/sec) 2. Innervates intrafusal fibers 3. Stimulation results in stretch viii. Co-activation of alpha and gamma neurons by brain is normal b. Brain control of skeletal muscle i. Cerebellum & Cerebrum- receive data from golgi tendon organs & spindle apparatus 1. Cerebrum indirectly regulates muscle 2. Always negative ii. Basal Ganglia- regulates muscle tone Cardiac Muscle A. Anatomy of Cardiac Muscle a. Striated b. Involuntary c. Intercalated discs d. Larger and numerous mitochondria e. Large sarcoplasm f. Sarcoplasm reticulum less well developed than skeletal muscle g. Fibers branch freely to form 2 separate networks: i. Atrial ii. Ventricle 1. Stimulation of 1 fiber -> entire network due to intercolated discs (fused at gap junctions) 2. All or none of heart contraction 3. Contraction & relaxation occurs = 72 x/min 4. A long refractory period occurs = 300 msec B. Physiology of Cardiac Muscle a. Self-stimulating b. Nerve impulse simple increase or decrease rate Smooth Muscle A. Anatomy of Smooth Muscle a. Non-striated b. Involuntary c. Unordered myofilaments d. Line blood vessles, G.I., respiratory, urinary, reproductive tracts B. Miscellaneous a. Peristaltic waves = from circular & longitudinal smooth muscle b. Long fibers= 30-200 um: can still contract when stretched c. Uterine muscles= stretched 8x normal length by birth d. Contraction = due to influx of extracellular Ca++ as sarcolemma deplorizing e. Ca++ binds with calmodulin (protein) f. Kinase= phosphorylates cross-bridges -> binds to actin g. Amount of depolarization -> reg. amount of Ca++ influx -> reg. amount of cross-bridge formation h. Graded responses occurs i. Slow & sustained contractions j. Divided into 2 functional groups i. Single unit smooth muscle: 1. A number of gap junctions: act as a “single unit” 2. Display pacemaker activates: myogen, widespread in body ii. Multi-unit smooth muscle: 1. Few gap junctions 2. Fibers act independently; found in arteries, respiratory system, iris, and goose bump muscle (erectorpili muscles) Naming Skeletal Muscles: 1. Rectus- fibers run parallel to midline 2. Transverse- fibers run perpendicular to midline 3. Oblique- fibers run diagonal to midline 4. Maximus- largest muscle 5. Minimus- smallest muscle 6. Longus- longest muscle 7. Brevis- shortest muscle 8. Biceps- 2 origins 9. Triceps- 3 origins 10. Quadriceps- 4 origins 11. Deltoid- triangular shape 12. Trapezius- trapezoidal 13. Serratus- saw-toothed 14. Rhomboideus- diamond or rhomboid 15. Flexor- decreases joint angle 16. Extensor- increases joint angle 17. Abductor- moves bone away from midline 18. Adductor- moves bone toward midline 19. Levator- upward movement 20. Depressor- downward movement 21. Sphincter- decreases opening size 22. Tensor- increases rigidity 23. Supinator- turns palm forwards 24. Pronator- turns palm backwards A. Muscles for Facial Expression a. Frontalis- draws scalp forward, raises eyebrows, wrinkles forehead b. Occipitalis- draws scalp back c. Orbicularis Oris- closes, protrudes & shapes lips d. Zygomaticus Major- Draws mouth up and out (smiling) e. Levator Labii Superioris- raises upper lip f. Depressor Labii Inferioris- lowers lower lip g. Buccinator- causes cheeks to cave in -> sucking h. Mentalis- raises and protrudes lower lip; raises skin on chin -> pouting i. Oribicularis Oculi- closes eye j. Corrugator Supercilli- lowers eyebrows -> frowning k. Levator Palpebrae Superioris- raises upper eyelid B. Muscles of Lower Jaw Movement a. Masseter- elevates jaw; closes mouth; chewing b. Risorius- moves jaw side to side c. Lateral Pterygoid- opens mouth C. Muscles for Tongue Movement a. Genioglossus- depresses and protracts tongue b. Styloglossus- elevates and retracts tongue c. Hyoglossus- depresses and draws sides down D.Muscles of Oral Cavity a. Digastric- opens mouth, elevates hyoid bone b. Stylohyoid- elevates hyoid bone c. Mylohyoid- elevates and opens mouth E. Muscles of Eyeball Movement a. Superior Rectus- rolls eyeball up b. Inferior Rectus- rolls eyeball down c. Lateral Rectus- rolls eyeball laterally d. Medial Rectus- rolls eyeball medially F. Muscles for Head Movement a. Sternocleidomastoid- draws head forward, rotates face left & right b. Splenius Capitis- rotates head left and right G.Abdominal Wall Muscles a. Rectus Abdominis- compresses chest, important for defecation, urination, and birthing b. External, Internal, & Transverse Oblique- compresses abdomnen H. Breathing Muscles a. Diaphragm- increases lung volume; air rushes in b. External Intercostals- elevates rib; air rushes in c. Internal Intercostals- depresses rib; air forced out I. Pectoral Girdle Muscles a. Subclavius- depresses clavicle b. Pectoralis Minor- depresses scapula c. Trapezius- elevates clavicle; rotates scapula d. Levator Scapulae- elevates scapula e. Rhomboideus Major & Minor- adducts scapula J. Muscles that Move the Humerus a. Pectoralis Major- flexes, adducts, & rotates arm b. Latissimus Dorsi- extends, adducts, & rotates arm c. Deltoid- Abducts, flexes, and extends arm d. Subscapularis- rotates arm medially e. Infraspinatus- rotates arm laterally f. Teres Major- extends arm g. Teres Minor- adducts arm K. Muscles that Move the Forearm a. Brachialis- flexes elbow b. Biceps Brachii- supines forearm c. Triceps Brachii- extends elbow L. Muscles that Move the Wrist & Hand a. Flexor Carpii Radialis- flexes & abducts wrist b. Flexor Digitorium- flexes middle phalange of each finger c. Extensor Carpi Ulnaris- extends & adducts wrist d. Extensor Digitorium- extends phalanges M.Thigh Muscles a. Psoas- flexes & rotates laterally b. Gluteus Maximus- extends & rotates laterally c. Gluteus Medius- abducts & rotates medially-important injection site and sciatic nerve damage d. Gluteus Minimus- abducts and rotates medially e. Adductor Longus & Brevis- adducts, flexes, & medially rotates N. Muscles of Pelvic Floor a. Pubococcygeus- raises pelvic floor; draws anus towards pubis b. Coccygeus- raises pelvic floor; pulls coccyx forward after defecation and birthing O. Muscles of the Perineum= region b/w the thighs a. Bulbocavernosus- expels last drops of urine b. Ischiocavernosus- maintains erection of penis & clitoris c. External Anal Sphincter- decrease orifice size d. Quadriceps Femoris- 4 heads; all 4 extend tibia & fibula i. Rectus Femoris ii. Vastus Lateralis iii. Vastus Medialis iv. Vastus Intermedialis e. Sartorius- flexes & rotates laterally; crossing legs f. Hamstrings- 3 muscles; all 3 flex leg & extend thigh i. Biceps Femoris ii. Semitendinosus iii. Semimembranosus
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