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A A A Level Biology > 5.5.1 neuronal comm. muscles > Flashcards

5.5.1 neuronal comm. muscles Flashcards

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1
Q

what are the two types of nervous system?

A

somatic nervous system

autonomic nervous system

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2
Q

what is the somatic nervous system

where do impulses travel to

A

under conscious control

|&raquo_space;used voluntarily to decide to do something like move muscles in arm and carries impulses to body muscles

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3
Q

what is the autonomic nervous system

where do impulses travel to

A

works constantly and is subconcious
»automatic response like heartbeat digestion ect
carries impulses to glands, smooth muscle of intestines and cardiac muscle

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4
Q

what does the autonomic nervous system split into

A

sympathetic- outcome increases activity

parasympathetic- decreases activity eg heart rate after exercise

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5
Q

examples of effects of sympathetic nervous system

A

funnily enough does opposite of what u think :) but most of these result in opposite effects in body

reduced saliva production from saliva gland
reduced peristalsis (contractions in stomach to digest)
decreased urine secreted

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6
Q

examples of effects of parasympathetic nervous system

A

bronchial muscle contracts in lungs

digestion increases in small intestine and more gastric juice secreted for digestion in stomach

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7
Q

how is the nervous system separated in terms of structurally

A

CNS- brain and spinal chord

peripheral nervous syst. all neurones that connnect CNS to rest of the body. Sensory neurones which carry nerve impulses from receptors to CNS and motor neurones which carry away

the peripheral is either AUTONOMIC or SOMATIC

and the autonomic is either sympathetic or parasympathetic

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8
Q

which neurotransmitters are released in:

somatic NS
sympathetic
parasympathetic

A

acetylcholine

Noradrenaline

acetylcholine

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9
Q

how myelinated is the neurone in the somatic nervous system

where do neurones go here

A

heavily myelinated single neurone from CNS to effector organs

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10
Q

how myelinated is the neurone in the sympathetic nervous system

where do neurones go here

A

lightly myelinated pre-ganglionic axons and unmyelinated post-ganglionic

neurones go from CNS to effector

but includes adrenal medulla necreting noradrenaline

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11
Q

how myelinated is the neurone in the sympathetic nervous system

where do neurones go here

A

lightly myelinated pre-ganglionic axons and unmyelinated post-ganglionic

neurones go from CNS to effector

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12
Q

describe the stages of the power stroke

A

1) myosin cross bridges attaches to actin myofilament
2) working stroke, the myosin head pivots and bends as it pulls on the actin filmament slding it towards the M line (ADP and P released)
3) as new ATP attaches to myosin head, the cross bridge detaches
4) as ATP is split into ADP and P, cocking of the myosin head occurs. (hydrolysis)

Process repeats

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13
Q

In the sliding filament model what happens to the:
>I band when muscle contracts
>A band when muscle contracts
what is each band?

A

I band- gets smaller as actin slides between myosin
A band- stays same as myosin length unchanged

A band is Anistrophic so dArk band
I is Isotrophic so LIght band

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14
Q

what does a greater overlap of the actin filaments mean for the contraction

A

there is a greater force

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15
Q

what happens to to the middle of the sarcomere during contraction?

A

stays the same

but the H band (where actin filaments overlap) gets smaller as greater overlap between actin and mysoin

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16
Q

what does a relaxed muscle need to contract

A

ATP and Ca2+ ions

whereas contracted to relaxed is passive

muscles work in antagonistic pairs

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17
Q

what are the thick and thin filaments made from in the sliding filament model

A

thick is myosin (these have the heads on that grab and hold actin/myosin filaments slide relatively )

thin is actin

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18
Q

what is myoglobin

A

iron- and oxygen-binding protein found in the skeletal muscle tissue

together with mitochondria makes ATP for contraction
transports oxygens to mitochondria in sarcolemma

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19
Q

an individual muscle is composed of hundreds of______
each of these is composed of many_______
these have distinctive banding due to _____

A

muscle fibres

myofibrils

microfilaments (also part of cytoskeleton) eg actin and myosin

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20
Q

which filaments are in the I/ light band

A

only actin microfilaments

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21
Q

which band has both actin and myosin filaments

A

A/ dark band

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22
Q

which zone has just myosin microfilaments

A

H zone

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23
Q

what does ATP do to the myosin head

A

alters the shape of the myosin head so that actin and myosin can slide relative to one another (ATP cocks the myosin head)

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24
Q

what do Ca+ ions do to myosin head

A

remove the protein tropomyosin which blocks the binding site on the actin molecule which the myosin heads can attach to during the sliding of actin/myosin over each other

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25
Q

what causes grey matter to be darker than white

A

many more nuclei (found in sensory and motor nerve pathway)

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26
Q

what are the 3 types of muscle

A

skeletal, cardiac and smooth(involuntary) muscle

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27
Q

what is skeletal muscle

A

make up most of body tissue. Voluntary movements

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28
Q

what is cardiac muscle

A

only in the heart, myogenic so contracts without need for nervous stimulus.
causes heart to beat in regular rhythm

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29
Q

what is smooth muscle

A

involuntary muscle found in places like walls of hollow organs such as stomach and bladddr and also walls of blood vessels and digestive tract. Also involved in peristalis

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30
Q

what is the fibre appearance of the 3 muscle types?

A

skeletal is striated

cardiac is specialised striated

smooth is non- striated

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31
Q

what is the arrangement of skeletal muscles

A

regularly arranged so muscle contracts in one direction

32
Q

what is the arrangement of cardiac msucles

A

cells branch and interconnect resulting in simultaneous contraction

33
Q

what is the arrangement of involuntary smooth msucle

A

no regular arrangement, different cells contract in different directions

34
Q

what is the contraction speed of the 3 types of muscles

A

skeletal is rapid

cardiac is intermediate

involunatry is slow

35
Q

what is the length of contraction for the 3 muscle types

A

skeletal is short

cardiac is intermediate

involuntary is long periods relatively

36
Q

what is the structure of skeletal muscles

A

muscles showing cross striations known as striated or striped muscle fibres are tubular and multinucleated

37
Q

what is the structure of cardiac muscle

A

doesnt show striations as much fainter

fibres branched and multinucleated

38
Q

what is the structure of involuntary muscle

A

show no cross striations

fibres are spindle shaped and unnucleated

39
Q

what is the sarcolemma

A

plasma membrane found in skeletal muscle containing muscle fibres

40
Q

how are skeletal muscle cells much longer

A

contain lots of nuclei and are formed from individual embryonic cells fusing together

> > > this makes the muscle stronger as if there were junctions between cells it would make it weaker

41
Q

what are T tubules and what is there purpose

A

parts of sarcolemma which fold inwards to spread electrical impulses through sarcoplasm

this is so that the WHOLE muscle fibre receives the impulse to contract at the same time.

42
Q

what is the sarcoplasmic reticulum

A

modified version of the endoplasmic reticulum which extends through muscle fibres providing calcium ions for muscle contraction

43
Q

what are myofibrils

A

long cyclindrical organelles made of protein which are specialised for contraction

when lined up in parallel are very powerful and provide max force when they contract together

44
Q

which proteins are in myofibrils

A

actin +
myosin

so basically myofibrils have myofilaments which make up the sarcomere!

45
Q

what happens to the sarcomere during contraction

A

reduced in legnth

46
Q

what makes the light bands light?

A

actin and mysosin dont overlap

47
Q

what is the Z line

A

found at the centre of each light band

the distance between adjacent Z lines is the sarcomere when muscle contracts the sarcomere shortens
actin is on z lines

48
Q

what is the H zone

A

lighter coloured region in the centre of dark bands
only myosin
muscle contractions shorten.

49
Q

what should you remember when drawing a sarcomere

A 
show 2 z lines to show understanding of sarcomere length
ensure heads present on myosin filaments
connect actin to the Z line
label light and dark bands
show position of H zone
50
Q

what are the properties of slow-twitch fibres and what are they used for

where do they get energy from

A

> fibres contract slowly
provide less contractions but over a longer period
used for endurance activities as they don’t tire easily

> energy from respiration
they have a rich supply blood vessels and mitochndria

51
Q

which proteins are slow-twitch fibres rich in

A

> myoglobin, a bright red protein which stores oxygen which makes fibres appear red

52
Q

where are slow twitch fibres found usually?

A

large proportions in muscle

this helps to maintain posture such as calf and back muscles. This are continuously contracting to keep body upright

53
Q

properties of fast- twitch fibres

where do they get their energy from?

A
  • contract very quickly
  • produce powerful contractions but only for short periods
  • used for short bursts of speed and power as they tire easily

get energy from anaerobic

54
Q

appearance of fast twitch fibres

which filaments do they contain

A

pale as they have low levels of myoglobin and blood vessels

contain more and thicker myosin filaments

they also contain creatine phosphate which is a molecule which rapidly generates ATP from ADP in anaerobic conditions.

55
Q

where are fast twitch fibres found

A

high proportions in muscles needing short bursts of energy such as biceps and eyes

56
Q

why does the dark band remain the same width when contracts?

A

as the myosin filaments themsleves havent shortened but the now overlap the actin filaments more

57
Q

what does the contraction of many sarcomeres mean

A

many myofibrils and muscle fibres are also contracting

58
Q

characteristics of actin

A

binding site for myosin heads which can be blocked by tropomyosin often which is help in place by troponin when muscles are relaxed

when join with mysoin form actin/myosin cross bridges

59
Q

what does myosin head need to detach from actin

A

ATP which is usually to reattach further along actin filament

60
Q

how is a muscle contraction triggered

A

When an action potential arrives at a neuromuscular junction where motor neurone and skeletal muscle fibre meet

there are lotssss of these junctions so muscle fibres contract simultaneously.

61
Q

why are there lots of neuromuscular junctions?

A

because if only one the muscle fibres would not contract altogther and contraction wouldnt be powerful

it would also be slower! as wave of contraction would have to travel across whole muscle

62
Q

what is a motor unit

A

all muscle fibres (supplied by a single motor neurone)

63
Q

if a strong force is needed how many motor unitswill be stimulated

A

a large numberrrr

64
Q

what diffuses from synapse to synaptic knob? and what effect does this have

A

calcium ions

which cause synaptic vesicles to fuse with the presynaptic membrane which releases acetylcholine to synaptic cleft and it binds to sarcolemma/ post synaptic membrane

65
Q

what is the effect of acetylcholine binding to the sarcolemma

A

sodium ion channels open and a wave of depolarisation sent across post synaptic membrane

66
Q

what prevents the muscle being overstimulated by wave of depolarisation

A

acetylcholine is broken down by acetylcholinesterase

chlorine and ethanoic acid diffuse back into neurone and recombine to acetylcholine with energy

67
Q

where does the wave of depolarisation from the sarcolemma go to

A

spreads through T tubules which are in contact with the sarcoplasmic reticulum (which absorbs and stores Ca2+ ions from sarcoplasm)

68
Q

what happens when wave of depolarisation reaches the sarcoplasmic reticulum

A

it stimulates calcium ion channels to open so calcium ions flows down a conc. gradient

> > > this floods sarcoplasm with Ca2+

69
Q

what is the effect of calcium ions in the sarcoplasm

A

bind to troponin causing it to change shape
»this pulls tropomyosin away from actin-myosin binding site so that myosin heads can bind there and form a cross bridge!!!

they also activate ATPase to break down/hydrolyse ATP which releases energy and then the myosin head can return back to origional position so it can bind another place

70
Q

what happens after actin filament and myosin head flex (what is released and why)

A

ADP so a new ATP molecule can bind there

ATP which releases energy and then the myosin head can return back to origional position so it can bind another place along actin

happens along as muscle is stimulated

71
Q

what is happening to actin/myosin cross bridges as stimulated

A

many breaking and forming which shortens sarcomere and contracts muscle

72
Q

where is energy provided in muscle contraction

A

ATP hydrolysis
ATP can come from-
>aerobic respiration by OXIDATIVE PHOSPHORYLATION in mitochondria of muscle cells
>anaerobic resp. when oxygen used faster than blood supply. ATP made by GLYCOLYSIS and pyruvate becomes lactic acid
>Creatine Phosphate- chemical stored in muscle , creatine acts as store of phosphate and phosphylation makes ATP, store used quickly so only for short term burst of exercise. replenished from phosphate of ATP

73
Q

how is muscle activity measured

what is it used to show

A

with ElectroMyoGram or EMG
an large output on EMG means increased force. electrodes attached

used to show characteritics of muscles when doing particular exercise

74
Q

what does muscle fatigue do/caused by

A

long lasting reduction in ability to contract/exert force

can be beneficial to body builders but not for normal as causes injury

75
Q

what is creatine phosphate

A

> Creatine Phosphate- chemical stored in muscle , creatine acts as store of phosphate and phosphylation makes ATP, store used quickly so only for short term burst of exercise. replenished from phosphate of ATP

A A A Level Biology (22 decks)

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