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1

The active binding sites to which myosin cross bridges attach during muscle contraction are found on the

Actin filaments

2

When a muscle fiber is stimulated by a motor nerve, the muscle fiber either will contact maximally or it will not contract at all.

All or none principle

3

The structure within skeletal muscle that spreads the nerve impulses rapidly throughout individual myofibrils

T tubules

4

The muscle that provides most of the force required for a movement

agonist

5

The specialized network of membranous tubules that stores calcium ions in a muscle fiber

Sarcoplasmic reticulum

6

The thick filaments of a myofibril are composed mainly of

Myosin

7

The muscle fiber that constitutes for approximately 50% of the total muscle fibers in most muscles of the body, in the normal, non athletic population.

Type I fibers

8

A muscle action in which the muscle generates force but does not change in length

Isometric contraction

9

low oxidative capacity, high glycolytic capacity, fast contraction speed, and a low level of fatigue resistance are characteristics of

Type II fibers

10

The striated appearance of skeletal muscle fiber is mainly due to the arrangement of

The A-band of a sarcomere contains

Actin and Myosin myofilaments


primary contractile proteins in muscles are

11

The muscle lengthens as contractile force is generated

Acentric contraction

12

During a progressive increase in exercise intensity, motor units

with small motor neurons are recruited first

13

The smallest functional unit of a muscle

Sarcomere

14

The process by which free fatty acids are broken down to yield multiple molecules of acetyl COA

Beta oxidation

15

The major source of energy for running a 440 yard race

Carbohydrate

16

The primary source of energy during a marathon is

Oxidative system

17

The two enzymes most commonly measured in order to assess the oxidative capacity of muscle tissues are

Succinate dehydrogenase
Citrate synthase

18

Anaerobic glycolysis begins with either glucose or glycogen and ends with

Lactic acid

19

The major metabolic waste product that causes the muscles and blood to have a lower ph during exercise of increasing intensity is

Lactate

20

represents depolarization of the atria

P wave

21

The volume of blood ejected from the heart with each contraction is called

Stroke volume

SV= ESV-EDV

22

what phase of the cardiac cycle does the diastolic pressure reflect

Relaxation

23

Skeletal muscles receive approximately ___% of the total cardiac output under resting conditions, but they can receive as much as ___% cardiac output during heavy endurance exercise.

15, 80

24

The structures within heart tissue that anchor individual cells together so they do not pull apart during contraction

Desmosomes

25

The volume of blood in the ventricles at the end of ventricular filling is called

End diastolic volume

26

Resistance vessels are also called

Arterioles

27

Represents repolarization of the ventricles

T wave

28

Represents depolarization of the ventricles

QRS complex

29

Mean pressure in the pulmonary artery is

15 mmHg

30

Found in skeletal muscle, serves to transport oxygen from the cell membrane to the mitochondria

Myoglobin