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Exercise Physiology > Muscle > Flashcards

Flashcards in Muscle Deck (43):
1

Three types of muscles

-skeletal
-cardiac
-smooth

2

Step 1 of muscular contraction

-nerve stimulation

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Step 2 of muscular contraction

-action potential

4

Action potential

an electrical current that must be generated in the sarcolemma

5

Step 3

Action must be propegated along sarcolemma

6

Step 4

intracellular Ca2+ levels must rise briefly

7

What ACH

-acetycholine, which is the neurotransmitter at neuromuscular junction

8

Four main characteristics of muscle

-elasticity
-excitability
-elasticity
-contractility

9

Excitability

ability to receive and respond to a stimuli

10

Extensability

Ability to be stretched

11

Elasticity

ability to recoil after stretched

12

Contractility

ability to shorten forcibly when stimulated

13

Four movement functions of muscle

-produce movement
-stabalize joints
-generate heat
-maintain posture

14

Three features of skeletal muscle

-nerve and blood supply
-connective tissue sheaths
-attachments

15

Sarcolemma

muscle fiber plasma membrane

16

Sarcoplasm

muscle fiber cytoplasm

17

Modified organelles

-myofibrils
-sarcoplasm
-t tubules

18

Myofibrils

-densely packed rod like elements
-account for 80% of the muscle cell volume

19

Myofibril features

-stirations
-sarcomeres
-myofilaments
-molecular composition of myofilaments

20

Sarcomere

-smallest contractile unit
-individual sarcomere align end to end and along myofibril, like boxcars of a train

21

Myofilaments

orderly arrangment of myosin and actin myofilaments within sarcomere

22

Actin myofilaments

-thin filaments

23

Myosin filaments

-thick filaments

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Molecular composition of thick filaments

-composed of the protein myosin
-during contraction, heads link thin and thick filaments together forming crossbridge

25

Molecular composition of thin filaments

-composed of protein actin

26

Troponin and tropomyosin

-regulatory proteins bound to actin

27

Elastic filament

composed of protein called titin

28

Titin

-holds thick filaments in place
-helps recoil after stretch

29

Sarcoplasmic reticulum

-network of smooth endoplasmic reticulum
-functions in regulation of intracellular Ca2+
-stores and releases Ca2+

30

T-tubules

-tube formed by protusion of sarcolemma deep into cell interior
-increases muscle fiber surface area
-allows electrical signal to reach deep into cell interior of each muscle finer

31

Sliding filament model of contraction

states that during contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more

32

contraction

the activation of cross bridges generate force

33

How are bridges made possible?

because of calcium release in the sarcoplasmic retiulum

34

depolarization

reduction of negative membrane potential

35

Polarization

movement of the membrane potential to the initial resting state

36

Excitation contraction coupling E-C

-events that transmit AP along sarcolemma (excitation) are coupled to sliding of myofilaments (contraction)

37

Step 1 of crossbridge cycle

-cross bridge formation
-high energy

38

Step 2 of crossbridge cycle

Working (power) stroke: myosin head pivots and pulls thin filament towards m line

39

Step 3 of cross bridge cycle

cross bridge development: ATP attaches yo myosin head, causing cross bridge detach

40

Step 4 of cross bridge cycle

cocking of myosin head, energy from hydrolysis of ATP "cocks" myosin head into high energy state

41

Creatine phosphate

Ca2+ re entry into SR-tension declines to zero

42

Glycolysis

first step in breakdown of glucose

43

3 factors of glycolysis

-does not require oxygen
-glucose is broken down into 2 pyruvic acid molecules
-2 ATP's are generated for each glucose