Case 9 - muscle and movement

Question 1

features of skeletal muscle

Answer 1

connected to bone
striated
voluntary
high power
usually relaxed

Question 2

features of cardiac muscle

Answer 2

heart
striated
involuntary
high power
pump (cyclic)

Question 3

features of smooth muscle

Answer 3

hollow organs
smooth
involuntary
low power
usually contracted

Question 4

neuromuscular junction diagram

Answer 4

Question 5

neuromuscular junction diagram

Answer 5

Question 6

what is in a sarcomere

Answer 6

a number of different proteins in highly organised structure

Question 7

how does muscle contract

Answer 7

by overlapping the filaments

using energy derived from ATP hydrolysis to power this mechanism which is progressively shortening the distances

Question 8

what is the thin filament

Answer 8

actin

Question 9

what is the thick filament

Answer 9

myosin

Question 10

where is tropomyosin normally sat

Answer 10

over the binding sites for myosin on actin

Question 11

what has to happen in order fr the myosin to bind to the myosin binding site on actin

Answer 11

the binding site has to be exposed. when there is little Ca2+ or none, tropomyosin moves down and covers the binding sites. means that the actin and myosin can’t interact and bind to each other therefore giving no muscle contraction

Question 12

what is the troponin complex

Answer 12

series of regulatory proteins and in the presence of calcium, they help to move that tropomyosin out of the myosin binding site and allows the actin and myosin to interact. you then get ATP hydrolysis that powers the whole process. effectively makes the muscle shorter

Question 13

striated muscle contraction series of events

Answer 13

1. ATP binds to the myosin head causing the dissociated of the actin-myosin complex
2. ATP is hydrolysed, causing myosin heads to return to their resting connotation
3. a cross bridge forms and the myosin head binds to a new position on actin
4. phosphate is released… myosin heads change conformation resulting in the power stroke. the filaments slide past each other
5. ADP is released

Question 14

what happens when there are high levels of calcium

Answer 14

you get contraction

Question 15

diagram with anatomy concerning excitation-contraction coupling

Answer 15

Question 16

what is the plasma membrane

Answer 16

the sarcolemma

Question 17

what are there lots of in the muscle cell

Answer 17

myofibrils

Question 18

what do the invaginations of the plasma membrane form

Answer 18

transverse tubules

Question 19

what interacts with the transverse tubule

Answer 19

the sarcoplasmic reticulum cisterns

Question 20

where does the action potential go

Answer 20

goes along the sarcolemma and finds its way down into the T tubules and the T tubule is running very close to the SR. t

Question 21

where is calcium stored

Answer 21

the SR.

when the muscle is relaxed, the Ca2+ will be locked up inside the SR

when the cells contract, Ca2+ will be released

Question 22

when do we get release of calcium

Answer 22

when a wave of depolarisation passes through the T tubule

Question 23

what does the twitch force depend on

Answer 23

how much calcium is released. bigger contraction when more calcium is released

Question 24

what are the two types of contraction

Answer 24

isometric
isotonic

Question 25

what is isometric contraction

Answer 25

a constant length and doesn't actually shorten

Question 26

what is isotonic contraction

Answer 26

a constant load

Question 27

what does isotonic muscle contraction produce

Answer 27

limb movement without change in muscle tension, whereas isometric muscle contraction produced muscle tension without a change in limb movement. most physical activities involve a combination of both forms of muscle contraction, although one form usually predominates

Question 28

more on isometric contraction

Answer 28

contraction is stronger the closer the muscle initial length is to the optimum length a muscle contracts but the joint is controls does not move

Question 29

more on isotonic contraction

Answer 29

contraction is faster the closer the muscle initial length is to the optimum length a muscle contracts and the joint angle it controls increases and decreases while the muscle either shortens or lengthens

Question 30

what is a muscle unit

Answer 30

muscle fibres innervated by a single motor neurone

Question 31

what is a motor unit

Answer 31

muscle unit plus its motor neurone

Question 32

what is a motor neurone pool

Answer 32

collection of neurones innervating a single muscle

Question 33

what is involved in fine control

Answer 33

few muscle fibres per motor unit

Question 34

what is involved in coarse control

Answer 34

any muscle fibres per motor unit

Question 35

how many motor neurones control a muscle

Answer 35

typically about 100

Question 36

what are the features of type 1 muscle

Answer 36

oxidative slow, red slow myosin response time moderate rate of Ca2+ pump transport moderate diameter high oxidative capacity moderate glycolytic capacity reistant to fatigue

Question 37

what are the features of type 2B muscle - 7

Answer 37

glycolytic fast, white fastest myosin response time high Ca2+ pump transport rate large diameter low oxidative capacity high glycolytic capacity non-resistant to fatigue

Question 38

what are the features of type 2A muscles - 7

Answer 38

glycolytic, fast, red fast myosin response time high Ca2+ pump transport rate small diameter very high oxidative capacity high glycolytic capacity resistant to fatigue

Question 39

which muscle type is good for long distance running and why

Answer 39

type 1 fibres are slow and oxidative and tend to rely on aerobic respiration to generate most of their force - long distance run at low speed

Question 40

which fibres fatigue slower than 2B

Answer 40

2A but generate a decent amount of tension

Question 41

what are 2B designed to do

Answer 41

give you high energy. relying on glycolysis anaerobic respiration to give out most of their power.

Question 42

what are the two mechanisms to increase the amount of force

Answer 42

recruitment of motor units firing rate of motor units (shortening the time between action potentials and the contractions sort of add together and the calcium is never fully mopped up by the SR)

Question 43

what is the sequence of recruitment in the gradation of muscle force

Answer 43

S->FR->FF

Question 44

what are the large motor unit properties

Answer 44

motor neurone: large, fast conduction, hard to excite Muscle fibres: many, type 2 (large, fast glycolytic) Activity: recruited if a strong contraction is required, usually inactive

Question 45

what are the small motor unit properties

Answer 45

motor neurone; small, slow conduction, easy to excite Muscle fibres: few, type 1 (small, slow, oxidative) Activity: first to be recruited, frequently active

Question 46

detailed stretch reflex diagram

Answer 46

Question 47

LMN muscle strength

Answer 47

weak

Question 48

what type of paralysis do you get with LMN lesion and why

Answer 48

flaccid - effectively damaged the wiring between the muscle and the spinal cord; cant get a message from the spinal cord to the muscle

Question 49

what is the muscle tone if you have a LMN lesion

Answer 49

hypotonia

Question 50

what is the type of reflex if there is a LMN lesion

Answer 50

hyporeflexia

Question 51

muscle strength in UMN lesion

Answer 51

weakness

Question 52

what type of paralysis do you get in UMN lesion

Answer 52

you get spasticity because the wiring is still there form the muscle unlike in an LMN lesion: can't get the message from the motor cortex to the spinal cord. you get sensitisation of the lower motor neurone pools so that they're responding in the absence of innovation from the motor cortex. that is why you get spastic paralysis

Question 53

what type of muscle tone is there in UMN lesion

Answer 53

hypertonia - thanks to sensitisation to lower motor pools

Question 54

what sort of reflexes do you get. in UMN lesion

Answer 54

hyperreflexia

Question 55

what is Babinski sign

Answer 55

may show a problem in the corticospinal tract. CST is a neural pathway that goes from your brain to spinal cord and helps control your movements. evaluate neuro only in patients above age of 2. the essential phenomenon appears to be recruitment of the extensor hallicus Longus, which consequent overpowering of the toe flexors. the movements of the other joints remain the same

Question 56

how what happens when the corticospinal tract is not functioning

Answer 56

 The corticospinal tract influences the segmental reflex in the spinal cord. When the corticospinal tract is not functioning properly, the result is that the receptive field of the normal toe extensor reflex enlarges at the expense of the receptive field for toe flexion. Toe extension is consequently elicited from what is normally the receptive field for toe flexion.

Question 57

what is the plantar reflex

Answer 57

a nociceptive segmentaal spinal reflex that serves the purpose of protecting the sole of the foot

Question 58

in what conditions has the extensor reflex been observed

Answer 58

hemorrhage, brain and spinal cord tumors, and multiple sclerosis, and in abnormal metabolic states such as hypoglycemia, hypoxia, and anesthesia.[2]