Muscles-continued

Question 1

4 Muscle Fiber Shapes (organization)

Answer 1

1. ) Circular ex: orbicularis
2. ) Convergent- come to a point; broad base and and inserts at narrow point ex: pectoralis
3. ) Parallel- fibers run straight ex: biceps brachii, rectus abdominis
4. ) Pennate- “feather”
   a. unipennate: all fibers on 1 side of 1 tendon ex: flexors/extensors in forearm
   b. bipennate: 1 tendon down middle w/ fibers on both sides ex: rectus femoris
   c. multipennate: more than 1 tendon ex: deltoids

Question 2

Muscle Attachments

Answer 2

1.) Origin- nonmovable end; expands a joint; red on models
2.) Insertion: movable end; blue on models
3.) Belly: what you are eating when eating a steak
Ex: Insertion for bicep is on the radial tuberosity

Question 3

Contraction Terms

Answer 3

1. ) Synergistic: muscles work together ex: bicep is flexor for forearm; brachialis inserts on coronoid process of ulna
2. ) Antagonistic: muscles do the opposite of each other ex: triceps extend forearm and bicep is antagonistic to tricep

Question 4

Skeletal Muscle Composition

Answer 4

Fiber- 1 skeletal muscle

Fasicle- bundle of fibers

Question 5

Connective Tissue

Answer 5

1. ) endomysium- white, thin, delicate C.T. surrounding one fiber where capillary exchange takes place
2. ) perimysium- wraps around bundle of cells/fasicle
3. ) epimysium- stronger C.T. that covers many bundles/fasicles
4. ) fascia- loose C.T.
5. ) tendon- attaches muscle to bone; aponeurosis (generic name) is a flat sheat like tendon for biding over a wide area ex: lumbodorsal fascia
6. ) retinaculum- C.T. found at wrist and ankle that holds tendons down

Question 6

Breakdown of Muscles

Answer 6

1 muscle fiber contains many myofibrils and the myofibrils are made up of myofilaments: actin and myosin

Question 7

Sarcolemma

Answer 7

plasma membrane of skeletal muscle cell; the endomysium is exterior to this structure

Question 8

Transverse Tubule (T-Tubule)

Answer 8

continuations of sarcolemma; takes depolarization deep into muscle cell; blue on model

Question 9

Motor End Plate

Answer 9

specialized region of sarcolemma that contains receptors for neurotransmitters; squiggly line on model

Question 10

Sarcoplasmic Reticulum (SR)
Terminal Cisternae

Answer 10

network surround myofibrils that stores and releases calcium so muscles can contract; peach colored network on model
expanded portion on either side of T-tubule

Question 11

Triad

Answer 11

made of 2 terminal cisternae and 1 t-tubule

Question 12

Sarcoplasm

Answer 12

muscle cell cytoplasm

Question 13

Myofilaments

Answer 13

Myosin- thick filament/dark band; has globular head
Actin- thin filament/light band; has binding site;
tropomyosin covers binding site on actin when muscle is relaxed; troponin is the binding site for calcium

Question 14

I Band

Answer 14

actin only/ thin filament

Question 15

A Band

Answer 15

the length of myosin

Question 16

Zone of Overlap

Answer 16

composed of actin and myosin

Question 17

H Zone

Answer 17

middle part of A Band; only myosin

Question 18

M Line

Answer 18

protein in middle of myosin

Question 19

Sarcomere

Answer 19

arrangement of actin and myosin in skeletal and cardiac muscle causing them to be striated/striped; z line to z line on actin

Question 20

Sliding Filament Theory

Answer 20

Z-discs never touch because actin and myosin don’t change length; as z discs come closer together the zone of overlap increases

Question 21

Excitation, Contraction, Coupling

Answer 21

depolarization on excitable membrane; sliding filament theory; coupled by release of calcium

Question 22

Neuromuscular Junction

Answer 22

where neuron and muscle cell come together (terminal end of axon + synaptic cleft/gap + motor end plate of sarcolemma)

Question 23

Motor Unit

Answer 23

1 motor neuron + the number of muscle fibers/cells it innervates with