CHAPTER 11

Question 1

function of skeletal muscle

Answer 1

moves/stabilizes the position of the skeleton, voluntary

Question 2

function of a cardiac muscle

Answer 2

circulates blood and maintains blood pressure

Question 3

function of a smooth muscle

Answer 3

moves food, urine etc

Question 4

name the muscle characteristics and functions

Answer 4

-excitability- responsiveness
-conductivity- wave of excitation
-contractility- shortens from stimulus
-extensibility- stretch between contractions
-elasticity - stretch and return to original

Question 5

muscle fibre is also called

Answer 5

muscle cell (myofibers)

Question 6

name the skeletal cell chain

Answer 6

skeletal- muscle fascicles (bundles)-muscle fibers (cell)-myofibril-sarcomere (functional unit)-myofilaments (myosin action)

Question 7

connective tissue wrappings

Answer 7

-endomysium- around muscle cell
-perimysium- around muscle fascicle
-epimysium-around entire muscle

Question 8

what is inside a muscle cell

Answer 8

-sarcolemma- plasma membrane
-sarcoplasm- cytoplasm
-myofibrils- protein cords
-glycogen- carbohydrate
-myoglobin red pigment with O2 for muscle activity
-multiple nuclei- pressed against sarcolemma
-myoblasts- stem cells where muscle fibres are made
-sarcoplasmic reticulum- smooth network around myofibril
-Triad- tuble with terminal cisterns and trans tubule
-myofilaments

Question 9

describe myofilaments

Answer 9

-Thick filament- myosin molecules, two chained intertwined
-Thin filaments- fibrous action (intertwined strands), tropomyosin molecules (blocks active sites on G actin) troponin molecule (calcium on tropomyosin molecule)
-elastic filaments- huge protein through thick filament and anchors Z disc to M line

Question 10

Contractile proteins and Regulatory proteins

Answer 10

myosin and action do the work of contraction

tropomyosin and troponin

Question 11

Siration and its bands

Answer 11

-result from myosin and actin
-A band- dark, has H band and M band

-I band- light, has Z disc

Question 12

sarcomere

Answer 12

segment from Z to Z disc

Question 13

sliding filament theory

Answer 13

1. H bands and I bands get smaller
2. Zones of overlap get larger
3. Z lines approach each other
4. A bands remain constant

Question 14

skeletal muscle can only contract if

Answer 14

nerve is stimulated

Question 15

Somatic motor neuron

Answer 15

-nerve cells in brainstem and spinal cord that have axons (nerve fibre) that attaches and serve skeletal muscles (one motor neuron each)

Question 16

motor unit

Answer 16

A motor unit is a group of muscle fibers that are controlled by a single motor neuron

small motor units- control (eye)
large motor units- strength (quads)

Question 17

synapse

Answer 17

Junction between two neurons that allow signal to pass between them

Question 18

Neuromuscular Junction

Answer 18

neuromuscular junction (NMJ) is the point of contact between the motor neuron and the muscle fiber forms,

a separate synapse with muscle fiber

-axon terminal- swollen end of nerve fibre
-synaptic cleft-gap between axon terminal and sarcolemma

Question 19

Acetylcholine (ACh) and acetylcholinesterase (AChE)

Answer 19

-a neurotransmitter in vesicles

-an enzyme breaking down ACh

Question 20

what does NMJ consist of

Answer 20

1. Synaptic terminal of neuron (vesicles with ACh)
   2.motor end plate (has junctional folds, contains AChE)
2. Synaptic cleft (space between neurons and muscle fibers)

Question 21

Toxins interfering with synaptic function can cause what

Answer 21

paralyzation

Question 22

Toxins and Paralysis

Answer 22

-Spastic paralysis- state of continual contraction
-tetnus- form of spastic paralysis caused by toxin
-flaccid paralysis- muscles are limp and cant contract
-botulism- food poisoning cause by toxin

Question 23

Rigor Mortis

Answer 23

-hardens muscles and stiffens body after death

-ATP production stops and cell membranes leak
-Ca2+ leaks out of SR and muscle contraction cycle in motion
-Ca2+ activates myosin-actin cross bridges
-lysosomes digest cross bridges

Question 24

4 phases of contraction and relaxation

Answer 24

Excitation: nerve action lead
to muscle action
- Excitation–contraction coupling: link the action
potentials on the sarcolemma to activation of the myofilaments to contract
* Contraction: muscle fiber develops tension and may shorten
* Relaxation: when stimulation ends, a muscle fiber relaxes and returns

Question 25

muscle length tension relationship

Answer 25

amount of tension generated by a muscle depends on how stretched or shortened it was before it was stimulated -short- weak contraction, filaments butt against Z discs stretched- weak contraction, minimal overlap between filaments

Question 26

Threshold

Answer 26

minimum voltage necessary to generate an action potential in the muscle fiber and produce a contraction -has to be reached for something to occur

Question 27

Twitch

Answer 27

-a quick cycle of contraction and relaxation when stimulus is at threshold or higher -after threshold

Question 28

latent period

Answer 28

very brief delay between stimulus and contraction * Time required for excitation, excitation–contraction, generating internal tension

Question 29

contraction phase

Answer 29

time when muscle generates external tension

Question 30

Relaxation phase

Answer 30

time when tension declines to baseline

Question 31

Isometric contraction

Answer 31

Muscle produces internal tension but external resistance causes it to stay the same length

Question 32

Isotonic contraction (two types)

Answer 32

-Muscle changes in length with no change in tension -Concentric contraction: muscle shortens -Eccentric contraction- muscle lengthens (ex slowly lowering weight

Question 33

Iso contraction phases

Answer 33

beginning- isometric -muscle rises, overcomes resistance, shortens (concentric) becomes isotonic, lowers and lengthens (eccentric)

Question 34

all muscle contraction depend on

Answer 34

ATP -depends on oxygen and organic energy sources (glucose)

Question 35

Two main pathways of ATP synthesis

Answer 35

-Anaerobic Fermentation- cells producing ATP in absence of oxygen, generates lactate from glucose -Aerobic respiration- produces far more ATP, no lactate

Question 36

immediate energy

Answer 36

short, intense excercise

Question 37

Muscles meet most ATP demand by borrowing _______ groups (Pi) from other molecules and transferring them to ___________

Answer 37

phosphate ADP

Question 38

Two enzyme systems control these phosphate transfers

Answer 38

Myokinase creatine kinase

Question 39

Phosphagen system

Answer 39

combination of ATP and CP which provides nearly all energy for short bursts of activity

Question 40

Anaerobic threshold (lactate threshold

Answer 40

point at which lactate becomes detectable in the blood

Question 41

Glycogen–lactate system

Answer 41

pathway from glycogen to lactate

Question 42

Muscle fatigue

Answer 42

progressive weakness from prolonged use of muscles

Question 43

VO2 max

Answer 43

- rate of oxygen consumption is constant and does not increase further with added workload * Proportional to body size * Peaks at around age 20 -dont want it to decline so maintain w physical activity

Question 44

Excess Post-exercise Oxygen Consumption (EPOC)

Answer 44

oxygen debt

Question 45

Difference between Slow(oxidative) and fast(glycolytic) twitch

Answer 45

Slow- motor unit/neurons smaller and weaker, ATP aerobic, Fatigue resistance good, color red fast- moter unit/neuron bigger and stronger, ATP anaerobic, fatigue resistance poor, color white pale

Question 46

muscle fiber types can be based from

Answer 46

muscle function, genetics, activity

Question 47

Muscle disorders

Answer 47

-aging -Dystrophy-degenerate and weaken (duchenne most common, cause by sex link trait) -myasthenia gravis- Autoimmune disease in which antibodies attack neuromuscular junctions