Exam 4: Muscular System Pt. 2 Innervations and Contractions

Question 1

one neuron may innervate _____ fiber/s

Answer 1

many

Question 2

is every skeletal muscle individually innervated?

Answer 2

yes

Question 3

all skeletal muscle is depolarized in response to _______

Answer 3

acetylcholine

Question 4

what muscle types use gap junctions instead of being individually innervated

Answer 4

cardiac and smooth

Question 5

Raynaud’s syndrome

Answer 5

overreaction to cold
constriction of blood vessels to extreme degrees
- blockage of Ca would decrease vasoconstriction
- Ca channel blockers

Question 6

Why do you think Ca blockers would effect heart, but not have an effect on skeletal muscle?

Answer 6

skeletal muscle relies on intracellular Ca

- the heart is all from external

Question 7

why do Ca blockers not have same level of effect on digestive system even though you get digestive effects?

Answer 7

digestive system has smooth muscle - smooth is dependent on extracellular

Question 8

why would it hit Ca channels in cardiac but not digestive if both smooth?

Answer 8

cardiac slightly diff than digestive

- Ca targets diff families

Question 9

neuromuscular blocking agents - anesthesiology

what does it target?

Answer 9

acetylcholine receptors

resistant to acetylcholinesterase - muscles relaxes

Question 10

do you think neuromuscular blocking agents can effect the diaphragm?

Answer 10

yes

- you can temporarily stop it - intubate them

Question 11

what is a motor unit composed of?

Answer 11

one neuron and all the muscle fibers it innervates

• only one type of fiber

Question 12

as a stimulus increases are more or less units recruited?

Answer 12

more increasing tension

Question 13

where can you find smaller motor units

Answer 13

in the hand because it requires precision

Question 14

the number of motor units active at rest

Answer 14

muscle tone

Question 15

muscles with higher degree of muscle tone respond ____ and use more ____ at rest

Answer 15

quickly

energy

Question 16

why are warm ups beneficial?

Answer 16

• result in heat production

- less prone to damage and have inc recruitment

Question 17

3 types of muscle fibers

Answer 17

type I, type IIA, type II B

Question 18

type I fibers

Answer 18

• endurance fibers - slow oxidative - slow twitch
• dependent on aerobic respiration
• high myoglobin content: lots of stored O2
• muscle fibers a darker red, wales have black bc underwater so long
• many mitochondria
• highly vascular
• slow to fatigue: do not fatigue easily
• slower contraction compared to others
• small fibers
• maintaining posture

Question 19

Type II B

Answer 19

• burst of strength- fast glycolytic fibers- fast twitch
• fast contractions
• anaerobic respiration: do not need as much O2, lower myoglobin
• store lots of glycogen
• not many mitochondria
• not many capillaries compared to type I
• large fibers
• last to recruit but do so quickly
• short intense movements - hitting baseball

Question 20

Type II A

Answer 20

intermediate - you can train one way or another

• mainly aerobic but larger store for anaerobic
• high myoglobin: less than type I
• red to pink color
• sprinting, walking

Question 21

Which type of muscle fiber predominates in pectoralis major muscle?

Answer 21

type II B - fast twitch

Question 22

which muscle fiber type predominates gastrocnemius

Answer 22

type I - endurance

Question 23

3 stages of a muscle twitch

Answer 23

latent, contraction, relaxation

Question 24

myogram

Answer 24

shows time vs force of contraction

Question 25

latent stage of muscle twitch

Answer 25

time tat stimulus is being communicated to sarcomere | - depolarization of membrane , releasing Ca

Question 26

contraction stage of muscle twitch

Answer 26

- increase in tension, hen work is being done | - troponin can bind Ca

Question 27

relaxation of muscle twitch

Answer 27

recovery period for muscle cell | - put Ca back into storage - sarcomere back to original shape, relaxed

Question 28

increase in stimulus strength results in _____

Answer 28

increased tension

Question 29

what causes an increase in muscle tension?

Answer 29

recruitment of more motor units

Question 30

tension in lifting notebook vs heavy back pack

Answer 30

more tension in backpack

Question 31

Treppe

Answer 31

stimulus is applied immediately after relaxation tension "steps up" with stimuli gets bigger and bigger until max tension to handle frequency - not the same at the beginning bc you are warming up - easier to recruit as you warm up - max not as high bc allowing them to fully rest

Question 32

wave summation

Answer 32

- higher frequency than treppe - stimulus applied before relaxation complete - tension increases, does not reach baseline until stimulus stopped - waves look piled on top of eachother - more recruitment of motor units since incomplete relaxation

Question 33

incomplete tetanus

Answer 33

wave summation nears max tension - still allows partial relaxation - it is the max you can get with wave summation

Question 34

tetanus

Answer 34

frequency of stimuli no longer allows for relaxation - max tension reached - NO relaxation - eventually hit fatigue

Question 35

stimulus frequency and tension types (4)

Answer 35

treppe, wave summation, incomplete tetanus, tetanus

Question 36

isometric muscle contractions

Answer 36

- develops tension without changing length | ex: lifting something heavy and you cannot budge it - no change in muscle length

Question 37

isotonic muscle contraction (2 types)

Answer 37

concentric and eccentric

Question 38

isotonic concentric muscle contraction

Answer 38

tension development while shortening

Question 39

isotonic eccentric muscle contraction

Answer 39

tension development while lengthening | ex: slow curls in gym - slowly lowering the weigh - muscle gets longer and you feel tension increase

Question 40

when does muscle fatigue occur (3)

Answer 40

- high energy demand is placed on muscles - dramatic variations in muscle recruitment - insufficient O2 - oxygen debt

Question 41

blood flow to muscles but the demand is higher than you reach with aerobic respiration - so you take on anaerobic respiration

Answer 41

oxygen debt

Question 42

results of muscle fatigue (3)

Answer 42

- inc glycolysis - accumulation of lactic acid - acidosis in cell dec enzymes involved in ADP rephosphorylation - muscles do not preform as well

Question 43

organ to recover from the lactic acid build up - cori cycle

Answer 43

liver

Question 44

glycolysis dependent tissues

Answer 44

``` skeletal muscle blood cells bone marrow renal medulla peripheral nerves hypoxic tissues ```

Question 45

cori cycle, what does the liver do?

Answer 45

gluconeogenesis: takes it backwards which costs liver energy, it invests ATP to take lactate to make glucose - releases glucose to bloodstream so cells that need glucose can have it cycle between cells producing lactic acid and liver clearing it out and providing sugar

Question 46

Rhabdomyolysis

Answer 46

breakdown/degeneration of skeletal muscle cell - cell contents released into blood stream (potassium K) life threatening due to effects on heart, kidney, liver

Question 47

3 ways to damage kidneys

Answer 47

direct toxicity - iron in myoglobin obstruction of tube- myoglobin interacts with glycprotein in kidneys and precipitates out vasoconstriction - due to inflammation

Question 48

hyperkalemia

Answer 48

too high K in blood | - throws off balance of ions - balance for nerves and muscles - can send someone into heart attack

Question 49

lactic acidosis

Answer 49

too acidic | - pH change, can get hypoxic

Question 50

uremia

Answer 50

wastes remaining in blood instead of being excreted in urine - kidney not filtering - clogged - vasoconstriction - back up of toxic material

Question 51

Myoglobinuria

Answer 51

myoglobin in urine | ex: casts

Question 52

best diagnostic marker for Rhabdomyolysis

Answer 52

serum CK (CPK)