10/30/2014 APPEARANCE

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1 APPEARANCE Striated: has a striped appearance due to the thickness of the protein fibers Smooth: protein fibers (which are arranged the same in striated muscle) is not as thick so you cannot see the pattern the fibers make The longest type of muscle fiber Striated and voluntary Are attached to bone in some way * direct/fleshy attachment: the muscle is fused to the bone + not common + where the muscle that cover the scalp * indirect attachments: uses a tendon to attach to bone Found in heart only Involuntary Striated Uninucleated Cells branch, forming what look like openings Cells are arranged to look like really long fibers, but are actually smaller cells attached at the intercalated discs Found in the digestive system, and other hollow organs (blood vessels, bladder, kidney, diaphragm, etc) No striations (proteins are still there, just not thick enough to see pattern) Involuntary Peristalsis- always pulsing in order to push substances through tubes (or to breath) 1

2 1) A motor neuron is connected to each muscle fiber (cell) 2) NMJ: connection b/w nerve fiber & muscle fiber; specialized section of sarcolemma where junction occurs in motor end plate 3) Synaptic knobs - (ends of nerve fibers) contain synaptic vesicles which store neurotransmitters - (chemicals which will enable the transfer of the nerve impulses to the muscle fiber) 4) Motor Unit: motor neuron & muscle fibers it controls (may be many fibers or just a few; all would contract simultaneously within the unit) - Going to draw pic on board, and you copy in your notebook. 4) Synaptic transmission a. Nerve impulse from brain/spinal cord travels via a motor neuron to the synaptic knob b. Synaptic vesicles release neurotransmitter (acetylcholine or ACH) c. Neurotransmitter diffuses across the synaptic cleft and binds to receptor sites on motor end plate d. Muscle action potential is generated & muscle fiber is stimulated to contract Click on pic Name & Date on paper 1. Name 1 function of muscles? 2. List the 3 types of muscle tissues? 3. What is the name of the outside covering around a muscle? 4. What is a muscle cell called? 5. List the organization of a muscle in order from smallest to largest. (4 words for full credit) Extra Credit (10pts): What does ACH stand for? 1. the ability of a muscle to receive an electrical impulse and respond to that information 2. the ability to shorten 3. the ability to be stretched 4. the ability to resume its resting length after being stretched back to normal 2

3 Muscles can only contract So they have to be pulled back to normal by another muscle. So every muscle has a partner that works opposite of it Called antagonistic pairs So, when the bicep contracts, it pulls the tricep to relaxation 2 proteins = (actin and myosin) arrange themselves in a specific pattern called the sarcomere Actin (thin)- small protein that attaches to sides Myosin (thick) -large protein that hangs from the actin This pattern is present in all muscle fibers The sarcomere is what controls contraction 7 easy steps of muscle contraction 1. ACH released from synaptic vesicles 2. ACH diffuses across synaptic cleft & binds to receptors on motor end plate; generates muscle action potential 3. Muscle impulse (series of action potentials) travels down sarcolemma until it reaches T- tubule openings 4. Muscle impulse travels down T-tubules & reaches cisternae of the Sarcoplasmic reticulum 7 easy steps of muscle contraction 5. Ca 2+ diffuses from cisternae into sarcoplasm 6. Ca 2+ causes active site of actin to be uncovered and a linkage forms b/w actin & myosin 7. Actin slides inward as myosin power strokes: and muscle fiber shortens (requires ATP) 3

4 1. Enzyme, acetylcholinesterase, breaks down ACH 2. Ca 2+ actively transported back into cisternae (requires ATP) 3. Actin-myosin linkages break 4. Actin slides back 5. Muscle fiber relaxes 1. Temporalis 2. Orbicularis Oculi 3. Zygomaticus 4. Orbicularis Oris 5. Pectoralis Major 6. Deltoid 7. Biceps brachii 8. Rectus Abdominis 9. Internal oblique 10. Adductor longus 11. Gracilis 12. Sartorius 13. Tibialis anterior 14. Fibularis longus 15. Vastus medialis 16. Vastus lateralis 17. Rectus femoris 18. Tensor fasciae latea 19. Brachioradialis 20. External oblique 21. Sternocleidomastoid 22. Masseter 23. Frontalis 1. Infraspinatus 2. Teres minor 3. Teres major 4. Gluteus maximus 5. Adductor magnus 6. Biceps femoris 7. Semitendinosus 8. Gastrocnemius 9. Soleus 10. Calcaneal tendon 11. Semimembranosus 12. Gluteus medius 13. External oblique 14. Latissiumus dorsi 15. Triceps brachii 16. Deltoid 17. Trapezius The Stapedius: is a muscle in your ear! 4

5 Review NMJ Click on pic I. Threshold Stimulus: smallest stimulus that will cause contraction of a muscle fiber II. All-or-None Response: muscle fibers contract completely or not at all III. Recruitment (like the army!) Recruitment A. Motor units respond in an all-or-none manner (all the cells in the unit contract or none do) B. Low level simulation: few motor units activated (like picking up an empty water pitcher) C. High level simulation: additional motor units activated (like adding water to the pitcher and making it heavier, thus more units activated to support the additional weight) IV. Twitch Contraction A. Definition: single contraction and relaxation of a muscle (ex. Eye twitch) B. Myogram graph of the force of contraction over time 5

6 V. Types of Contraction A. Sustained Contraction: muscle contraction in which twitches have combined such that a complete relaxation is not achieved B. Tetanic Contraction: sustained, forceful contraction that lacks even partial relaxation (the normal way our muscles contract) C. Muscle tone: small amt of sustained contraction that results from repeated impulses from spinal cord (ex. Maintaining posture) I. Muscles almost always function in groups (like quadriceps) II. Prime mover: muscle in group responsible for most of movement (like rectus femoris) III. Synergists: muscle(s) that assist prime mover (like V. medialis, V. lateralis, & V. intermedius) IV. Antagonists: muscle(s) that resist prime mover (like hamstring) 1. ATP supplies E for muscle contraction 2. Primary storage substance for energy in muscle cells is CREATINE PHOSPHATE 1. Oxygen needed to support aerobic respiration (breakdown of glucose in the presence of O 2 to release E) 2. O 2 transported in blood bonded to hemoglobin; in muscles, Myoglobin is the temporary storage pigment 1. Usually, muscles get plenty of O 2 from respiratory circulatory system (aerobic respiration) 2. When muscles used strenuously, body can t keep up & switches to anaerobic respiration 3. Oxygen debt occurs as lactic acid builds up in muscle fibers, must be repaid as liver converts lactic acid back to glucose 6