Muscule Physiology

Question 1

Tendons

Answer 1

bands of tough, fibrous CT that connect muscle to bone

Question 2

Fasciculus:

Answer 2

small bundle of muscle fibers

Question 3

Muscle fiber

Answer 3

long, multinucleated cell that generates force when stimulated

Question 4

Myofibril

Answer 4

portion of muscle composed of thin & thick myofilaments (actin & myosin)

Question 5

Actin & myosin

Answer 5

contractile proteins in muscle

Question 6

Role of connective tissue:

Answer 6

Stabilizes & supports components of skeletal muscle

Surrounds muscle at each organizational level

Question 7

What are the 3 layers of connective tissue in muscle?

Answer 7

Epimysium:
Perimysium
Endomysium

Question 8

Epimysium:

Answer 8

covers whole muscle

Question 9

Perimysium

Answer 9

covers bundles of muscle fibers (fasciculi)

Question 10

Endomysium

Answer 10

covers individual muscle fibers

Question 11

Characteristics of Connective Tissue

Answer 11

Sheaths coalesce to form tendons at each end of muscle
Force generated by muscle is transferred to tendon & bone
Epimysium helps prevent spread of signal for muscle activation

Question 12

Elastic component of CT contributes to

Answer 12

Force & power production (like recoil of rubber band)

Stretch-shortening cycle

Question 13

Eccentric action

Answer 13

elongation

Question 14

Concentric action

Answer 14

shortening

Question 15

Sarcomere

Answer 15

Basic skeletal muscle unit
Capable of force production & shortening
Arrangement of protein filaments gives striated appearance

Question 16

Components of sarcomere

Answer 16

Z lines
H zone
I bands
A band
M line

Question 17

Z line

Answer 17

at each end of sarcomere

Question 18

H zone

Answer 18

in middle of sarcomere, contains myosin

Question 19

I bands

Answer 19

at edges of sarcomere, contain actin

Question 20

A band

Answer 20

overlapping actin & myosin

Question 21

M line

Answer 21

middle of H zone, holds myosin in place

Question 22

What happens as the sarcomere shortens:

Answer 22

Actin filaments slide over myosin
H zone disappears as actin filaments slide into it
I bands shorten as actin & myosin slide over each other
Z lines approach ends of myosin filaments

Question 23

What happens as sarcomere relaxes:

Answer 23

It returns to original length
H zone & I bands return to original size & appearance
Less overlap between actin & myosin

Question 24

What makes up myosin filament?

Answer 24

Has globular head, hinged pivot point, & fibrous tail

Question 25

Head of myosin filament?

Answer 25

made up of enzyme myosin ATPase

Question 26

Tails of myosin filament?

Answer 26

intertwine to form myosin filament

Question 27

What is the crossbridge of myosin made up of?

Answer 27

Consists of 2 myosin molecules, with 2 heads

Question 28

Action of crossbridge:

Answer 28

Interacts with actin Develops force to pull actin over myosin Features different isoforms of ATPase

Question 29

Type I (slow-twitch)

Answer 29

``` Slow to reach peak force production Low peak force High capacity for oxidative metabolism Fatigue-resistant Endurance performance ```

Question 30

Type II (fast-twitch)

Answer 30

``` Rapidly develop force High peak force Low capacity for oxidative metabolism Fatigue easily Sprint, short-term performance ```

Question 31

What is the increase in delivery of oxygen to muscle caused by?

Answer 31

Increase in # of capillaries per muscle fiber Increase in capillary density Increase in concentration of myoglobin, which increases rate of oxygen transport from capillaries to mitochondria

Question 32

What is the enhanced ability for aerobic metabolism caused by?

Answer 32

Increase in size & number of mitochondria in muscle | Increase in ability to produce ATP

Question 33

What are the effects of resistance training?

Answer 33

hypertrophy | hyperplasia

Question 34

Hypertrophy

Answer 34

Increase in size of muscle fibers Results from addition of protein & new myofibrils to existing fibers, making them larger Requires addition of myonuclei to support increase in muscle fiber size

Question 35

Hyperplasia

Answer 35

Increase in number of muscle fibers | Occurrence is controversial