muscle

Question 1

skeletal muscle structure

Answer 1

multinucleated

Question 2

cardiac muscle structure

Answer 2

single nucleus
intercalating disks

Question 3

smooth muscle structure

Answer 3

mononucleated

Question 4

what does skeletal muscle form from in utero

Answer 4

mononucleated myoblasts

Question 5

can myoblasts self repilcate

Answer 5

no- can’t replace if damaged
hence scar tissue

Question 6

what attaches muscle to bones

Answer 6

tendons

Question 7

when injured what can skeletal muscle cells do

Answer 7

replaced by satellite cells

undergo hypertrophy to copensate

Question 8

1 skeletal muscle fibre is made of lots of

Answer 8

myofibrils

Question 9

what are myofibrils made from

Answer 9

sarcomeres- the repeating unit

Question 10

thick filaments are made from ____ and contain

Answer 10

myosin

cross bridges

Question 11

thin filaments are made from

Answer 11

actin

Question 12

what causes cross bridge to attach to actin

Answer 12

hydrolysis of ATP- ATP gets converted to ADP

Question 13

what causes the cross bridge to detach from actin

Answer 13

attachment of ATP

Question 14

role of troponin, tropomyosin and Ca²⁺

Answer 14

tropomyosin covers myosin binding site, helped by troponin

Ca²⁺ stops this by binding to troponin making it pull tropomyosin away

Question 15

what does the sarcoplasmic reticulum store

Answer 15

Ca2+ ions

Question 16

what do the transverse tubules act as

Answer 16

conduction system- AcH travels down it to reach the sarcoplasmic reticulum

Question 17

muscle units consist of

Answer 17

motor neurons and muscle fibres

Question 18

force exerted by muscle

Answer 18

tension

Question 19

force exerted on muscle

Answer 19

load

Question 20

contraction with constant length

Answer 20

isometric- holding still

Question 21

contraction with shortening length

Answer 21

isotonic- running

Question 22

a single action potential to a muscle fibre is called

Answer 22

a twitch

Question 23

contraction time depends on

Answer 23

Ca²⁺

Question 24

whats tetanus

Answer 24

multiple twitch added together- summation

Question 25

tetanic tension vs twitch tension

Answer 25

tetanic is greater- Ca²⁺ never gets low so no re blocking

Question 26

optimal length l₀ is

Answer 26

the muscle length that gets the greatest **isometric** tension

Question 27

second way ATP is used in muscles

Answer 27

ends contractions by pumping Ca²⁺ back into sarcoplasmic reticulum

Question 28

what does fatigue prevent

Answer 28

fatigue- prevents using up all ATP leaving myosin stuck bound to actin

Question 29

what causes fatigue in short, high intensity exercise

Answer 29

* increased K+ * increased lactic acid * increased ADP inhibits cycle

Question 30

what causes fatigue in long, low intensity exercise

Answer 30

* decreased muscle glycogen * decreased blood glucose * dehydration * central command fatigue- no "will to win"

Question 31

fast vs slow muscle fibre types

Answer 31

fast- myosin has high ATPase slow- myosin has low ATPase

Question 32

structure of oxidative fibres

Answer 32

increased O2 delivery and phosphorylation red fibres with low diameters

Question 33

structure of glycolytic fibres

Answer 33

increased glycolytic enzymes and glycogen white fibres with a large diameter

Question 34

3 types of muscle fibres

Answer 34

slow oxidative (I) fast oxidative (IIa) fast glycolytic (IIb)

Question 35

slow oxidative fibres (I)

Answer 35

resist fatigue

Question 36

fast oxidative fibres (IIa)

Answer 36

intermediate resistance to fatigue

Question 37

fast glycolytic fibres (IIb)

Answer 37

fatigue quickly

Question 38

increased number of active motor units

Answer 38

recuitment

Question 39

order of recruitment

Answer 39

slow oxidative then fast oxidative then fast glycolytic

Question 40

naural control of motor units depends on

Answer 40

frequency of action potentials to motor units recruitment of motor units

Question 41

what does aerobic exercise increase

Answer 41

mitochondria vascularisation fibre diameter

Question 42

what does anaerobic exercise increase

Answer 42

diameter and glycolysis

Question 43

in smooth muscle cycle, what does ATP do

Answer 43

makes binding

Question 44

what does calcium bind to in cycle of smooth muscle

Answer 44

calmodulin

Question 45

in skeletal muscle 1 action potential…

Answer 45

released enough Ca²⁺ to saturate ALL troponin sites

Question 46

in smooth muscle 1 action potential…

Answer 46

only activates SOME troponin sites so contractions can be graded

Question 47

smooth muscle always has

Answer 47

tone- constant level of Ca²⁺ to keep a constant tension

Question 48

smooth muscle types

Answer 48

single or multi unit

Question 49

simgle unit smooth muscle

Answer 49

* many cells with **gap junctions** * contractions in synch * has pacemaker cells * stretch evokes contraction

Question 50

single unit muscle is found in

Answer 50

GIT, uterus, small blood vessels

Question 51

multiunit smooth muscle

Answer 51

* few or no gap junctions * richly innervated * doesn't respond to stretch

Question 52

multi unit smooth muscle can be found in

Answer 52

airways, large arteries, hairs