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Biology-Corinna > 15.Nervous Coordination And Muscles > Flashcards

15.Nervous Coordination And Muscles Flashcards

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1
Q

What are the two forms of coordination in animals

A

Nervous system

Hormonal system

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2
Q

How does hormonal system form coordination

A

Produces chemicals transported in blood plasma to target cells
Target cells have specific cell surface membrane receptors
Change in conc of hormone stimulates them
Results in slower, less specific form of communication
Response long lasting and wide spread

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3
Q

Comparison of hormonal and nervous system

A

Communication by : Chemicals / nerve impulses
Transmission by : Bloody system / neurones
Transmission is : Relatively slow / very rapid
Travel to : all body, only target cells respond/ specific parts
Response is : Widespread / localised
Response is : Slow / fast
Response is : Long lasting / short lived
Effect is : Permanent irreversible / temporary reversible

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4
Q

What makes up motor neurone

A

Cell Body- contains cell organelles, high amount of rough ER
Dendrons - extensions of body subdivide into dendrites
Axon - sing long fibre carries impulse away from cell body
Schwann cells- surround axon, protect it, provide electrical insulation, carry out phagocytosis and nerve regeneration
Myelin sheath - rich lipid, if have it called myelinated neurone
Node of ranvier - constrictions between adjacent Schwann cells no myelin sheath

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5
Q

What are the three types of neurone

A

Sensory - transmit from receptors to intermediate/motor neurone, one long dendron takes impulse to cell body, then axon take away

Intermediate/relay - transmit impulses between neurones

Motors- transmit from intermediate or relay to effector such as gland or muscle, long axon and many short dendrites

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6
Q

What can a nerve impulse be defined as

A

Self propagating wave of electrical activity that travels along axon membrane, it’s a temporary reversal of the electrical potential difference across the axon membrane.

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7
Q

What is happening when the axon is at resting potential (what happens to maintain/achieve it)

A
  • Phospholipid bilayer prevents sodium ions and potassium ions diffusing across it
  • channel proteins called sodium potassium pump actively transport 3 sodium ions out of axon, and two potassium ions in to axon
  • creates a electrochemical gradient as more positive ions outside so outside is positively charged
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8
Q

What are the two types of skeletal muscle

A

Fast twitch

Slow twitch

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9
Q

What are the characteristics of fast twitch fibres

A
  • strength
  • rapid movement
  • sprinter
  • Anaerobic
  • fewer blood vessels
  • small amount energy released quickly
  • less mitochondria
  • Less myoglobin
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10
Q

What are the characteristic of flow twitch fibres

A
  • stamina
  • endurance
  • marathon runner
  • aerobic
  • many blood vessels
  • large amount energy released slowly
  • more mitochondria
  • more myoglobin
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11
Q

What is the sliding filament theory

A
  • The process where actin and myosin filaments slide last one another during muscle contraction
  • myosin filaments pull the actin filaments
  • the Z plates pulled closer together
  • I band becomes narrower
  • H zone become narrower
  • sarcomere shortens
  • A band stays same width- myosin length doesn’t change
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12
Q

What’s the structure of myosin

A
  • Two proteins
  • Fibrous protein arranged into filament made of several hundred molecules from the “tail”
  • globular proteins formed into two bulbous structures at one end form the “head”
  • thicker
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13
Q

What’s the structure of actin

A
  • Globular protein
  • molecules arranged into 2 long chains that are twisted around one another to form helical strand
  • tropomyosin forms long thin threads that are wound round the actin filaments

-thinner

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14
Q

What’s a neuromuscular junction

A

-Point where motor neurone meets skeletal muscle fibre, there’s many along muscle fibre

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15
Q

What’s the advantage of many neuromuscular junctions

A

-muscle contraction is simultaneous
-muscle contraction is rapid and powerful
-motor unit is when all muscle fibres supplies by single motor neurone act together as single functional unit
-

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16
Q

What’s the structure of skeletal muscle

A
  • Individual muscles are made up of millions of tiny muscle fibres called myofibrils
  • collectively are very powerful
  • muscle composed of smaller units bundled into progressively larger units
  • separate cells have fused together into muscle fibres, share nuclei and sarcoplasm.
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17
Q

Comparison of neuromuscular and cholinergic synapse

A
  • Excitatory / excitatory or inhibitory
  • Neurone to muscle / neurone to neurone
  • only motor neurone / motor,sensory, intermediate
  • action pot ends here / new action pot produced
  • acetylcholine binds to receptors on muscle fibre / acetylcholine binds to receptor on post synaptic neurone
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18
Q

What happens during muscle stimulation (start of muscle contraction)

A
  • Action potential reaches neuromuscular junctions simultaneously
  • causes calcium ion protein channels to open and calcium ions diffuse into synaptic knob
  • calcium ions cause synaptic vesicles to fuse with presynaptic membrane and release acetylcholine into synaptic cleft
  • acetylcholine Diffuses across synaptic cleft, bind with receptors on muscle cell causing it to depolarise
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19
Q

What happens during muscle contraction

A
  • Action pot travels down T tubules into the fibre and branches out throughout sarcoplasm
  • tubules in contact with endoplasmic reticulum of muscle which has actively transported Ca2+ from cytoplasm-low conc in cytoplasms
  • act pot opens calcium ion voltages gated channels, ca2+ diffuses out and into muscle cytoplasm
  • calcium ions bind to troponin, which causes the tropomyosin to unblock the binding sites on the actin filament
  • Myosin heads bind to actin filament, to form cross bridge
  • ADP dissociates and the myosin head changes angle forming power stroke and pulling the actin filament
  • ATP attaches to myosin head, calcium ions activate enzyme ATPase which hydrolysed ATP to ADP causing it to detach and resets back to original shape/angle
  • if calcium conc stays high process repeats
  • c
20
Q

What’s the action potential

A
  • when stimulus is sufficient size and detected by receptor, energy causes temporary reversal of charges
  • negative charge of inside -65V becomes +40-known as action potential
  • part of axon is depolarised
  • depolarisation occurs because channels in axon membrane change shape, open voltage gated channels.
21
Q

What’s the process of a nerve impulse

A
  • resting pot (k+ voltage gated channels open, na+ closed)
  • energy of stimulus causes some sodium voltage gated channels in axon membrane to open, na+ diffuse into axon along electro chemical gradient, positively charged, trigger reversal of potential difference -depolarisation
  • na+ diffuse into axon, increase potential so more channels open (voltage gated)
  • action potential at +40V, sodium channels close
  • k+ open electrical gradient that prevents further outward movement is reversed, k+ diffuse rapidly out
  • outward diffusion of k+ causes temporary overshoot of electrical gradient, inside is more negative than usual (hyperpolarisation) k+/na+ pump moves k+ in and na+ out, testing potential re-establishes
22
Q

How does a action potential move along an unmyelinated axon

A

Propagated

  • resting potential
  • stimulus causes influx of na+ ions
  • reversal of charge on axon membrane, depolarisation
  • localised electrical currents established by the influx of sodium ions causes opening of sodium voltages gated channels as sodium diffuses up along axon depolarising next section
  • behind the depolarising region, sodium channels shut and potassium channels open, potassium leave axon along electrochemical grad
  • outward movement of k+ lowers potential in axon, repolarisation of axon
  • resting potential established by k+/na+ pump
23
Q

The passage of action potential along myelinated axon

A
  • Action potentials only occur at nodes of ranvier
  • localised circuits go from node to node, so action potentials jump from node to node
  • still has depolarisation and resting potentials and depolarisations
24
Q

What factors affect, the speed of action potential travelling

A
  • Myelin-electrical insulator prevents action potentials forming so jumps node to node increases conductance
  • diameter of axon-greater the diameter the fast the conductance, due to less leakage of pins from larger axon
  • temperature-affects rate of diffusion of ions, higher temp faster nerve impulse, energy for active transport come fro respiration, controlled by enzymes, above certain temp denatured
25
Q

What’s the all or nothing principle

A
  • Certain level of stimulus called threshold
  • below threshold no action potential, no impulse generated
  • any stimulus above threshold will generate action potential and then a nerve impulse
26
Q

What’s the refractory period

A

Period after an action potentials was generated, when inward movement of voltage gated channels are closed. Impossible for further action potential to be generated

27
Q

What are the 3 purposes of refractory period

A

Ensures propagated in one direction only

Produces discrete impulses

Limits number of action potentials

28
Q

What are neurotransmitters

A

Chemicals which transmit information from pre synaptic neurone to post synaptic neurone

29
Q

What’s the synaptic cleft

A

The gap between pre synaptic and post synaptic membrane

30
Q

Features of synapses

A

Unidirectionality-pass in one direction, only post synaptic have has protein receptor channels

Summation-two types
Spatial summation - umber of different presynaptic neurones together release enough neurotransmitter to exceed threshold together trigger action potential

Temporal summation- single presynaptic neurone releases neurotransmitter many times over short period if conc exceeds threshold new action pot generated

31
Q

How do inhibitory synapses operate

A
  • pre synaptic neurone releases neurotransmitters that bind to chloride ions protein channel on post synaptic neurone
  • neurotransmitter causes chloride channels to open
  • chloride ions move into post synaptic by facilitated diffusion
  • binding of neurotransmitter opens nearby potassium protein channels
  • potassium ions diffuse out into synapse
  • inside postsynaptic is more negative
  • membrane potential increases to -80mV
  • hyperpolarisation and makes it’s less likely that new action potential created as larger influx of sodium ions needed.
32
Q

What’s the function of synapse

A

Act as junctions

They allow single impulse to initiative new impulses in number of different neurones at synapse - single stimulus creates number of simultaneous responses

Allow a number of impulses to be combined at synapse-nerve impulses from receptors reacting to diff stimuli to contribute to one single response

33
Q

How can drugs act in a synapse

A

1-stimulate nervous system by creating more action potentials in postsynaptic neurone

1-inhibit nervous system by creating fewer action potentials in postsynaptic neurone

34
Q

How does painkillers affect synapse

A

Work like endorphins- block the sensation of pain, Biden to specific receptors in the brand used by endorphins and mimic the effects of endorphins

35
Q

How do antidepressants affect synapses

A

Seratonin is neurotransmitter involves in sleep regulation and emotional states, reduced amount is thought to cause clinical depression

Prozac affects serotonin within synaptic clefts-may prevent it being destroyed

36
Q

What does GABA and Valium do

A

GABA inhibits formation of action potentials when burning to post synaptic neurone

Valium enhances the binding of GABA

37
Q

Action potential across a cholinergic synapse

A

1-action potential arrives
2-calcium voltage gated channels open
3-facilitates diffusion of calcium ions creates a signal
4-vesicles containing acetylcholine fuse with presynaptic membrane
5-acetylcholine released into synaptic cleft
6-acetylcholine diffuses across synaptic cleft and binds to receptor sites on sodium ion protein channels on the postsynaptic neurone
7-sodium channels open, sodium ions diffuse into post synaptic knob
8-acetylcholinesterase hydrolysed acetylcholine into choline and ethanoic acid
9-choline and at Hanoi’s avid diffuse into presynaptic neurone
10-ATP released by mitochondria used to recombine chloride and ethanoic acid into acetylcholine which is stored back in vesicles

38
Q

What are the three types of muscle and where are they found

A

Cardiac muscle- exclusively in heart

Smooth muscle-walls of blood vessels and gut

Skeletal muscle- makes up bulk of body muscle (only group that act under voluntary, conscious control)

39
Q

What are myofibrils

A

The tiny muscle fibres than make up muscles

Myofibrils line up parallel to eachother in order to maximise strength

40
Q

What is muscle made of

A

Composed of smaller units of myofibrils bundled together into progressively larger units

Muscle fibres-made of individual cells that fused together and share sarcoplasm-hollow

41
Q

What’s an I band

A

Light bands

Just actin

42
Q

What’s an A band

A

Dark band

Overlapping of myosin and actin

43
Q

What’s the z lines

A

Z plate where actin is bonded to

Marks the sarcomere

44
Q

What’s the h zone

A

Section of only myosin

45
Q

What happens during muscle relaxation

A
  • when nervous stimulation ceases, and calcium ions actively transported back into endoplasmic reticulum using energy from hydrolysis of ATP
  • reabsorption of ca+ allows tropomyosin to block actin filament again
  • myosin heads unable to bind to actin filaments, contraction ceases, muscle relaxes
  • force of antagonistic muscles can pull filaments out from between myosin (to a point)
46
Q

Where does the energy for muscle contraction come from

A

ATP

  • reabsorption of calcium ions
  • movement of myosin heads
  • ATP generates from ADP during aerobic respiration of pyruvate in mitochondria, which are common in muscle cells
  • in very active muscle demand is greater, rapidly generate ATP anaerobically using phosphocreatine and glycolysis
47
Q

How does phosphocreatine generate ATP

A

Cannot be directly supplied to muscle so regenerates atp

Phosphocreatine is stored in muscle and acts as reserve supply of phosphate, which is available immediately to combine with ADP and reform ATP
-phosphocreatine store replenished using phosphate from ATP when muscle relaxes

Biology-Corinna (22 decks)

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