Skeletal muscle

Question 1

three types of muscle

Answer 1

striated (skeletal,cardiac) smooth

Question 2

where is smooth muscle found

Answer 2

blood vessels, vas deferent, airways, uterus, GI itract, bladder etc. places it can constrict and dilate

Question 3

how are skeletal muscle cells multinucleate

Answer 3

the cells are combined in the womb as we develop as a baby into longer muscle fibre so there are multiple nuclei, all from individual muscle cells. fibre size grows as we grow

Question 4

how are skeletal muscle cells treated after injury

Answer 4

myoblasts cannot replace muscle cells. satellite cells (stem cells) form new muscle fibres or hypertrophy (other muscles try to get stronger to compensate). lots of scar tissue

Question 5

what repeating unit allows muscle to contract

Answer 5

sarcomere made up of myosin filament surrounded by actin filament. titan holds myosin in place

Question 6

how do muscles contract

Answer 6

myosin heads pull towards each other. actin helical structure can interact with myosin easily due to lots of binding sites. lots of Atp binding sites. great capacity for contraction

Question 7

powerstroke

Answer 7

series of structural changes in the actomyosin cross bridge driven by hydrolysis of ATP

Question 8

what ion does muscle contraction need

Answer 8

calcium

Question 9

what partially covers myosin binding site to block it to avoid random unnecessary contractions

Answer 9

tropomyosin cover myosin and troponin holds in position. calcium binds to troponin which causes a change in shape which causes tropomyosin to pull away. if calcium is not there the site is blocked again

Question 10

what do traverse tubules do

Answer 10

allow signal to reach the part of the cell it needs to by going deeper inside muscle cell as muscle cells are quite thick

Question 11

sarcoplasmic reticulum

Answer 11

membrane bound structure inside myocyte that contains calcium ions

Question 12

how is calcium taken back into storage to relax muscle cell after contraction

Answer 12

pumped against concentration gradient into sarcoplasmic reticulum powered by ATP

Question 13

if one motor neurone is damaged or fails howcome you won’t lose muscle contraction or function in the whole body part eg bicep

Answer 13

one motor neurone is connected to many muscle fibres in the part. so if one neurone dies you have so many left still working

Question 14

force exerted by muscle is

Answer 14

tension

Question 15

force exerted on muscle is

Answer 15

load

Question 16

contraction with constant length is

Answer 16

isometric

Question 17

contraction with shortening length is

Answer 17

isotonic

Question 18

contraction with increasing length is

Answer 18

lengthening

Question 19

contraction time occurs between

Answer 19

start of tension and time when we have peak tension

Question 20

contraction time depends on

Answer 20

calcium

Question 21

isometric has ____ latent period but _____ contraction event

Answer 21

shorter, longer

Question 22

as load increases, contraction velocity and distance shortened ____

Answer 22

decreases

Question 23

tetanic tension

Answer 23

longer sustained contractions for as long as we want to but then we relax. due to increased frequency of action potentials. calcium doesn’t get low enough to allow troponin yo reblock myosin binding sites due to action potentials

Question 24

over stretching is bad because

Answer 24

less overlap of filaments means less tension between (actin and myosin filaments)

Question 25

how are muscles so manoeuvrable

Answer 25

lever system (antagonistic groups of muscles) amplifies muscle shortening velocity

Question 26

what is fatigue

Answer 26

safety mechanism made up to prevent muscles using vast amounts of ATP which could cause rigor and would mean muscles would not be able to activate new X bridge cycles

Question 27

high intensity, short duration exercise problems

Answer 27

too much potassium outside cell causes conduction failure, too much lactic acid causes proteins to not work because not at optimum ph, too much ADP and Pi inhibits X bridge cycle, delaying myosin detachment from actin filaments

Question 28

long term low intensity exercise problems

Answer 28

run out of glycogen, low blood glucose, dehydration

Question 29

central command fatigue

Answer 29

cerebral cortex cannot excite motor neurons. no will to win

Question 30

oxidative skeletal muscle fibres

Answer 30

lots of mitochondria which leads to oxidative phosphorylation, more vascularisation to deliver more oxygen and nutrients, contain myoglobin which leads to increase oxygen delivery, red fibres with low diameters

Question 31

glycolytic skeletal muscle fibres

Answer 31

few mitochondria, more glycolytic enzymes and glycogen, lower blood supply, white fibres with large diameters

Question 32

3 types of muscle fibres

Answer 32

slow oxidative, fast oxidative, fast glycolytic (fast means has myosin molecules that have high ATPase activity, slow do not)

Question 33

what order is muscle fibre recruited

Answer 33

slow oxidative, fast oxidative, fast glycolytic

Question 34

neural control of muscle tension depends on

Answer 34

frequency of action potentials to motor units and recruitment of motor units

Question 35

what can cause decrease in muscle mass

Answer 35

denervation atrophy or disuse atrophy

Question 36

what can increase muscle mass

Answer 36

hypertrophy

Question 37

aerobic exercise causes

Answer 37

increase in mitochondria and increase in vascularisation so exercise type can depends on what muscle fibre types u have

Question 38

anaerobic exercise causes

Answer 38

increase in fibre diameter and increase in glycolysis so exercise type can depends on what muscle fibre types u have