Exam 2 - Chapter 10

Front 1

Functions of skeletal muscle

Back 1

- Produce voluntary skeletal movement

- maintain body position

- support soft tissues

- guard body openings

- maintain body temperature

- store nutrient reserves

Front 2

4 skeletal muscle structures

Back 2

- muscle tissue (muscle fibers)

- connective tissue

- nerves

- blood vessels

Front 3

What do nerves control and what are they controlled by?

Back 3

Control voluntary muscles and are controlled by nerves of the central nervous system

Front 4

What do blood vessels do?

Back 4

Supply large amounts of oxygen and nutrients, carry away waste

Front 5

Three layers of connective tissue from outside to inside

Back 5

Epimysium, perimysium, endomysium

Front 6

What does the epimysium cover and how does it connect?

Back 6

Covers the whole muscle (the exterior collagen layer), connects to the deep fascia

Separates muscle from surrounding tissue

Front 7

What does the perimysium cover and what does it contain?

Back 7

Covers the fascicles (muscle fiber bundles), contains blood vessels and nerve supply to fascicles

Front 8

What does the endomysium cover and what does it contain?

Back 8

Covers the individual muscle fibers, contains capillaries, nerve fibers (contains muscle cells), and myosatellite cells (stem cells that repair damage)

Front 9

Where do the endomysium, perimysium, and epimysium come together?

Back 9

At the ends of muscles to form connective tissue attachment to bone matrix

Front 10

What is the sarcolemma and what does it surround?

Back 10

The cell membrane of a muscle cell, surrounds the sarcoplasm

Front 11

What muscle structure begins contractions?

Back 11

Sarcolemma begins contractions through a change in transmembrane potential

Front 12

What to transverse tubules (t-tubules) do?

Back 12

Transmit action potential through the cell and allow the entire muscle fiber to contract simultaneously

Front 13

What is the sarcoplasmic reticulum and what does it store? What structure does it form?

Back 13

A membraneous structure surrounding each myofibril, stores calcium

Forms terminal cisternae attached to t-tubules

Front 14

How does calcium get released from the sarcoplasmic reticulum?

Back 14

Action potential triggers release of calcium

Front 15

What do terminal cisternae do?

Back 15

Concentrate calcium via ion pumps, release calcium into sarcomeres to begin contraction

Front 16

What is a triad formed from?

Back 16

1 t tubule and 2 terminal cisternae

Front 17

What are myofibrils?

Back 17

Lengthwise subdivisions within muscle fiber that make up bundles of protein filaments (myofilaments)

Front 18

What are myofilaments are responsible for and what are the two types?

Back 18

Responsible for muscle contraction

Thin (actin) and thick (myosin) filaments

Front 19

What are sarcomeres?

Back 19

The contraction units of muscle and structural units of myofibrils

Front 20

What forms the visible patterns (striations) within myofibrils?

Back 20

Sarcomeres (alternating thick, dark filaments and thin, light filaments)

Front 21

What are titin and what do they do?

Back 21

Strands of protein that reach from tips of think filaments to z line and stabilize the filaments

Front 22

What is required for muscle contraction?

Back 22

Calcium

Front 23

Five levels of skeletal muscle

Back 23

1: skeletal muscle (surrounded by epimysium, contains fascicles)

2: muscle fascicle (surrounded by perimysium, contains muscle fibers)

3: muscle fiber (surrounded by endomysium, contains myofibrils)

4: myofibril (surrounded by SR consists of sarcomeres)

5: sarcomere (contains thick and thin filaments)

Front 24

How are muscle contractions caused and what determines the interactions?

Back 24

Caused by interactions of thick and thin filaments, structures of protein molecules determine interaction

Front 25

F actin structure

Back 25

2 twisted rows of globular g actin (active sites of g actin bind to myosin), very strong and stable

Front 26

What does nebulin do?

Back 26

Holds f actin strands together

Front 27

Structure and function of tropomyosin

Back 27

Double strand that prevents actin myosin interaction

Front 28

Troponin structure and function

Back 28

Globular g protein with 3 subunits, binds tropomyosis to g actin (controlled by calcium)

Front 29

What happens to initiate contraction

Back 29

Calcium binds to receptor on troponin molecule, troponin-tropomyosin complex changes exposing active site of f actin, myosin binds to actin

Front 30

What do myosin heads do during contraction?

Back 30

Interact with actin filaments and form cross bridges, pivot to produce motion

Front 31

Sliding filament theory of skeletal muscle contraction

Back 31

Thin filaments of sarcomere slide towards m line between thick filaments, width of a zone stays the same but z lines get closer together and H zone and I bands get smaller

Front 32

Steps of contraction

Back 32

- arrival of action potential at neuromuscular junction (action potential: travels from nerve axon to synaptic terminal)

- release of ACh into synaptic cleft

- ACh binds to motor end plate causes a sodium ion rush into sarcoplasm

- action potential of sarcolemma is generated by sodium ions and leads to excitation contraction coupling

- recovery in which ACh is removed by AChE and there is a return to the initial state

Front 33

What is excitation contraction coupling and what does it require?

Back 33

Action potential reaches triad, releasing calcium and triggering contraction

Required myosin heads to be cocked (loaded with ATP energy)

Front 34

5 steps of contraction cycle

Back 34

Exposure of active sites, formation of cross bridges, pivoting of myosin heads, detachment of cross bridges, reactivation of myosin

Front 35

What does contraction duration depend on?

Back 35

Duration of neural stimulus, number of free calcium ions in sarcoplasm, availability of ATP

Front 36

All or none principal of tension production and what does it depend on?

Back 36

As a whole, the muscle fiber is either contracted or relaxed

Depends if number of pivoting cross bridges, fibers resting length at time of contraction, frequency of stimulation

Front 37

What does the number of pivoting cross bridges depend on?

Back 37

Amount of overlap between thin and thick filaments

Front 38

What does tension produced by a whole skeletal muscle depend on?

Back 38

Internal tension and external tension on elastic extracellular fibers by muscle fibers and the total number of muscle fibers stimulated

Front 39

What are the two types of skeletal muscle tension?

Back 39

Isotonic contraction(concentric and eccentric) and isomeric contraction

Front 40

Isotonic contraction and the two subdivisions

Back 40

When skeletal muscle changes length resulting in motion

Concentric - if muscle tension is greater than resistance, muscle shortens

Eccentric - if muscle tension is less than resistance, muscle lengthens

Front 41

Isomeric contraction

Back 41

Skeletal muscle develops tension but is prevented from changing length (iso = same, metric = length)

Front 42

How are resistance and speed of contraction related?

Back 42

Inversely related, the heavier the resistance, the slower the contraction takes to start/ shortening to begin

Front 43

After contraction, a muscle fiber returns to resting length by

Back 43

Elastic forces, gravity, or opposing muscle contractions

Front 44

What is creatine phosphate

Back 44

The storage molecule for excess ATP energy in resting molecule

Front 45

What are the two ways in which cells produce ATP

Back 45

Aerobic metabolism of fatty acids in the mitochondria and anaerobic glycolysis in the cytoplasm

Front 46

What are the results of muscle fatigue

Back 46

Depletion of metabolic reserves, damage to the sarcolemma and SR and t tubules, low ph (lactic acid), muscle exhaustion and pain

Front 47

What does the cori cycle do and where does it take place?

Back 47

Removes and recycles lactic acid in the liver

Front 48

What are the three types of muscle fibers?

Back 48

Fast, slow, and intermediate fibers

Front 49

Fast fibers

Back 49

Contract quickly, have large diameters and glycogen reserves, few mitochondria, and have strong contractions so they fatigue quickly

Front 50

Slow fibers

Back 50

Have small diameter, more mitochondria, high oxygen supply, and contain myoglobin, are slow to contract and fatigue

Front 51

Intermediate fibers

Back 51

Mid sized, low myoglobin, have more capillariesthan fast fibers so they are slower to fatigue

Front 52

Hypertrophy

Back 52

Muscle growth from heavy training increases diameter of muscle fibers, number of myofibrils, mitochondria, and glycogen reserves

Front 53

Atrophy

Back 53

Lack of muscle activity reduces muscle size, tone, and power

Front 54

Physical conditioning leads to

Back 54

Improved power and endurance; more myofibrils, mitochondria, blood vessels, slow and fast fibers, efficient respiration, red blood cells, glycogen reserves; a stronger heart, and higher lactic acid threshold

Front 55

Structure of cardiac tissue

Back 55

Striated, have a single nucleus, are small, have short and wide t tubules, have no triads, SR has no terminal cisternae, are aerobic, have intercalated disc's, and are only found in the heart

Front 56

Intercalated discs

Back 56

Specialized contact points between cardiocytes that join cell membranes of adjacent cardiocyted

Front 57

Functions of intercalated discs

Back 57

Maintain structure, enhance molecular/electrical connections, and conduct action potentials

Front 58

Why does the heart function like a single fused mass of cells

Back 58

The intercalated discs link cardiocytes mechanically, electrically, and chemically so what happens to one cells happens to all of them

Front 59

Functions of cardiac tissue

Back 59

Automaticity (controlled by pace maker cells), variable contraction tension (controlled by nervous system), extended contraction time, prevention of wave summation/tetanic contractions

Front 60

Smooth muscle structure

Back 60

Nonstriated, single nucleus, spindle shaped

Front 61

Where does smooth muscle form

Back 61

Around other tissues

Front 62

What does smooth muscle do in blood vessels, reproductive/glandular systems, digestive/urinary systems, and intergumentary systems?

Back 62

Blood vessels - regulates blood pressure/flow

Reproductive/glandular - produces movements

Digestive/urinary - forms sphincters and produces contractions

Intergumentary - arrector pilli muscles cause goose bumps

Front 63

Characteristics of smooth muscle cells

Back 63

Long/slender/spindle shaped, single central nucleus, no t tubules/myofibrils/sarcomeres/tendons/aponeuroses, scattered myosin fibers that have more heads per thick filaments, thin filaments attached to dense bodies, dense bodies transmit contractions from cell to cell (corkscrew contractions)

Front 64

Excitation contraction coupling in smooth muscle

Back 64

Free calcium in cytoplasm triggers contraction, calcium binds with calmodulin in sacroplasm which activates myosin light chain kinase, enzyme breaks down ATP and initiates contraction

Front 65

Length tension relationships in smooth muscle

Back 65

Thin and thick filaments are scattered, resting length is not related to tension development, functions over a wide range of lengths (plasticity)

Front 66

Two subdivisions of smooth muscle

Back 66

Multiunit smooth muscle - connected to motor neurons

Visceral smooth muscle - not connected to motor neurons, rhythmic cycles of activity controlled by pace setter cells

Front 67

Smooth muscle tone maintains what? What is it modified by?

Back 67

Maintains normal levels of activity, modified by neural, hormonal, or chemical factors

Front 68

Smooth vs. Striated muscle

Back 68

Different internal organization of actin and myosin, different functional characteristics