Muscle Physiology - Review Slides

Question 1

Each muscle consists of thousands of cylindrical cells called?

Answer 1

muscle fibers - these fibers are bundled together and wrapped in a connective tissue covering

Question 2

_____ surrounds entire muscle and blends into intramuscular tissue sheaths to form tendons. It also wraps each muscle fiber and separates it from neighboring fibers

Answer 2

epimysium

Question 3

_______surrounds a bundle of fibers called a fasciculus

Answer 3

perimysium

Question 4

_______ surrounds each muscle fiber and encloses fibers cellular contents

Answer 4

sarcolemma

Question 5

_____ contains nuclei that house genes, mitochondria, and other specialized organelles.

Answer 5

sarcoplasm

Question 6

the ___ provides structural integrity

Answer 6

SR

Question 7

How does training influence capillarization?

Answer 7

trained muscle has increased capillary-to-muscle fiber ratio

Question 8

why is enhanced capillarization beneficial for trained muscle?

Answer 8

expedites removal of heat and metabolic byproducts from active tissues and facilitates deliver of O2, nutrients, and hormones

Question 9

The total number of capillaries per area of muscle is ___% higher in endurance trained athletes

Answer 9

40

Question 10

What stimulates the capillary development?

Answer 10

Vascular stretch/shear stress on vessel walls from increased blood flow during exercise stimulates this development

Question 11

Myofilaments consist of actin and myosin that account for ~___% of myofibrillar complex

Answer 11

85

Question 12

Differences in sarcomere alignment and length affect muscle’s force-and power-generating capacity - How do pennate muscles differ from fusiform muscles? (3)

Answer 12

1. contain shorter fibers
2. possess more individual fibers
3. exhibit less ROM

Question 13

Fusiform fibers run parallel to muscle’s long axis and taper at the attachment points - what does this mean with regard to fiber and muscle length?

Answer 13

fiber length equals muscle length - this facilitates rapid muscle shortening

Question 14

Pennate fibers lie at oblique pennation angle; this allows for packing of a larger number of fibers into a smaller cross-sectional area - what does this mean with regard to contraction ability?

Answer 14

Allows the individual muscle fibers to remain short while overall muscle attains considerable length - this allows pennate muscles to generate considerable amounts of power

Question 15

_____ conduct action potentials into the interior of the muscle fiber

Answer 15

T-tubules

Question 16

Action potential is initiated & propagates in motor neuron axon.
Triggers the release of ____ from axon terminals. ____ binds to receptors on _____ ___ ____

Answer 16

ACH
ACH
motor end plate

Question 17

When ACh binds to receptors on the motor end plate, what opens?

Answer 17

Na and K channels

Question 18

What is the role of calcium in contraction?

Answer 18

calcium present binds to troponin causing movement of troponin and movement of tropomyosin which exposes binding sites for myosin on actin - crossbridges form and cycling occurs

Question 19

what are the two SR calcium channels?

Answer 19

Ryanodine (SR membrane) and DHP (t-tubule membrane)

Question 20

Termination of contraction - how does calcium get removed from the cytosol?

Answer 20

Ca binds to to other sites on Ca release channels in SR causing them to close (low affinity for Ca so not triggerd until [Ca] is high enough)

Question 21

Crossbridge cycle - high vs low energy form?

Answer 21

High - ADP and Pi bind to myosin, has high affinity for actin

Low - ATP bound to myosin, low affinity for actin

Question 22

The crossbridge cycle relies on ___ ____

Answer 22

ATP hydrolysis - splitting of a phosphate group from ATP –> ADP