Anatomy & Physiology Chapter 11 Physiology Of The Muscle

Front 1

What are the three major functions of the skeletal muscles?

Back 1

(a) endomysium, (b) perimysium, (c) epimysium

Front 2

Name some features of the muscle cell that are not found in other types of cells

Back 2

Excitability, contractibility, and extensibility

Front 3

What causes the striations observed in skeletal muscle fibers?

Back 3

The striations r a result of the A bands of sarcomeres appearing as relatively wide, dark stripes under the microscope, which alternate with narrower, lighter colored stripes formed by the I bands

Front 4

Why is the triad relationship between T tubules and the SR important

Back 4

The triad allows an electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the SR

Front 5

Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them

Back 5

Thin filament (actin, troponin,& tropomyosin): molecules strung 2gether like beads 2 form 2 fibrous strands that twist around each other.

Front 6

Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them

Back 6

Thick filament (myosin): shaped like golf clubs,w/ their long shafts bundled together 2 form a thick filament & their “heads” sticking out from the bundle

Front 7

What is the role of calcium ions (Ca++) in muscle contraction?

Back 7

Calcium ions released from the SR bind to troponin in the thin filament allow tropomyosin 2 shift frm its position blcking the active sites of actin molecules, thus initiating the chemical reactions that produce contractions

Front 8

Where does the energy stored in ATP come from?

Back 8

Catabolism of foods

Front 9

What is the role of myoglobin in muscle fibers?

Back 9

Myoglobin attracts oxygen molecules and holds them temporarily. When the oxygen concentration inside a muscle fiber decreases rapidly, it can be quickly resupplied from the myoglobin

Front 10

What are the three phases of a twitch contraction?

Back 10

Latent period, contraction phase, and relaxation phase

Front 11

What is tetanus? Is it normal?

Back 11

tetanus is a smooth, sustained contraction. Yes, tetanus is the kind of contraction exhibited by normal skeletal muscle organs most of the time

Front 12

What is meant by the term muscle tone?

Back 12

Muscle tone (tonic contraction) is a continual, partial contraction in a muscular organ

Front 13

Name four factors that influence the strength of a skeletal muscle contraction

Back 13

Metabolic condition of individual muscle fibers, recruitment of motor units, length-tension relationship, amount of load imposed on the muscle

Front 14

What is meant by the phrase “recruitment of motor units

Back 14

Number of muscle fibers activated

Front 15

How do slow, separate, autorhythmic contractions of cardiac muscle make it well suited to its role in pumping blood?

Back 15

Cardiac muscle does not normally run low on ATP and thus does not experience fatigue

Front 16

What produces the striations in cardiac muscle?

Back 16

Each myofibril comprises sarcomeres that give the whole fiber a striated appearance

Front 17

How are myofilaments arranged in a smooth muscle fiber?

Back 17

Thin arrangements of myofilaments crisscross the cell and attach at their ends to the cell’s plasma membrane.

Front 18

Isometric contraction

Back 18

type of muscle contraction in which muscle does not alter the distance between two bones; see isotonic contraction

Front 19

Isotonic contraction

Back 19

type of muscle contraction in which the muscle sustains the same tension or pressure and a change in the distance between two bones occurs

Front 20

Motor unit

Back 20

functional unit composed of a single motor neuron with the muscle cells it innervates

Front 21

Muscle tone

Back 21

tonic contraction; characteristic of muscle of a normal individual who is awake

Front 22

Myofibril

Back 22

very fine longitudinal fibers found in skeletal muscle cells; composed of thick and thin filaments

Front 23

Myofilament

Back 23

ultramicroscopic, threadlike structures found in myofibrils; composed of myosin (thick) and actin (thin)

Front 24

Neuromuscular Junction

Back 24

point of contact between nerve endings and muscle fibers; see motor endplate

Front 25

Sarcolemma

Back 25

plasma membrane of a striated muscle fiber

Front 26

Sarcomere

Back 26

contractile unit of muscle cells; length of a myofibril between two Z disks

Front 27

Sarcoplasm

Back 27

cytoplasm of muscle fibers

Front 28

Sarcoplasmic reticulum

Back 28

network of tubules and sacs in muscle cells; similar to endoplasmic reticulum of other cells

Front 29

T Tubules

Back 29

transverse tubules unique to muscle cells; formed by inward extensions of the sarcolemma that allow electrical impulses to move deeper into the cell

Front 30

Tetanus

Back 30

smooth, sustained muscular contraction caused by high-frequency stimulation

Front 31

Threshold Stimulus

Back 31

minimal level of stimulation required to cause a muscle fiber to contract

Front 32

Anatomy & Physiology Chapter 11 Physiology of the Muscular System

Back 32

Anatomy & Physiology Chapter 11 Physiology of the Muscular System