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Topic 6 Organisms response to change > Nerves > Flashcards

Nerves Flashcards

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1
Q

What two systems do animals have

A

Nervous and hormonal/endocrine

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2
Q

What are the chemical coordinators of the Endocrine system and where are they secreted

A

Hormones which are secreted into the blood

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3
Q

What are the chemical coordinators of the Nervous system

A

Neurotransmitters

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4
Q

Which of the endocrine and nervous system is longer lasting

A

Endocrine system

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5
Q

Which of the endocrine and nervous system have a faster speed of effect

A

Nervous system

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6
Q

What order does a stimulus move down the nervous system

A

Stimulus
Receptor
Sensory neurone
Co-ordinator
Motor neurone
Response

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7
Q

What is a motor neurone

A

A nerve cell that carries out an impulse from the CNS to an effector

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8
Q

What is a stimulus

A

A change in the external or internal environment that brings about a response in an organism

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9
Q

What is a co-ordinator

A

Region of Central nervous system where sensory information is interpreted

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10
Q

What is a receptor

A

a structure that detects a stimulus and generates a nerve impulse

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11
Q

What is a response

A

Action behavior brought about by an effector

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12
Q

What is a sensory neurone

A

A nerve cell that carries an impulse from a receptor to the CNS

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13
Q

What does the CNS consist of

A

Brain, Spinal cord,

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14
Q
A

Cranial nerves
Spinal nerve
Peripheral nerves
Sensory neurons
Motor neurons

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15
Q

Describe how the component part of the nervous system bring about a reflex

A

The stimulus activate receptors
An electron impulse travels along the sensory neuron to the closest CNS
An electrical impulse travels to the motor neuron to the effector
The response is brought out

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16
Q

What 5 structures make up a myelinated axon

A

Cell body
Dendrites
Axon
Myelin Sheath
Nodes of Ranvier

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17
Q

What is the cell body in the myelinated sheath

A

Contains the nucleus, cytoplasm, Endoplasmic reticulum and neurotransitters

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18
Q

What are the dendrites in the myelinated sheath

A

Finger-like projections of cytoplasm of cell body

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19
Q

What are the Axons in the myelinated sheath

A

Extension of cytoplasm which transmits impulses away from the cell body

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20
Q

What are the nodes of Ranvier in the myelin sheath

A

Junctions between Schwann cells

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21
Q

What do axons do

A

take information away from the cell body

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22
Q

What are some structural features of an axon

A

No ribosomes
Smooth surface
Branched further from the cell body
can have myelin insulation

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23
Q

What do dendrites do

A

Bring information towards the cell body

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24
Q

How many axons per cell

A

1 generally

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25
How many dendrites per cell
many dendrites per cell
26
What are some structural features of a dendrite
Rough surface Has ribosomes never has myelin insulation branched near cell body
27
What is resting potential difference across the membrane
-70mv
28
Is the interior axon positive or negative
negative
29
How is resting potential maintained
Active transport in the sodium potassium pump- 3Na+ out and 2K+ in Facilitated diffusion - more K+ ions leak out than Na+ ions leak in through the closed facilitated diffusion channels
30
What is meant by a reflex action
The rapid response carried out by the unconscious part of the brain An innate reaction which occurs everytime
31
How does the hormonal system differ from the nervous system
Slower than neuron Chemical not electrical Long lasting not short lasting
32
You smell
I know
33
How long does active potential last
about 3 milliseconds
34
What is action potential
When neurons are stimulated by a change in the resting potential
35
What is seen in the axon membrane during action potential
The voltage inside axon raises from -70mv to +40mv which is caused by voltage gated channels opening which allow ions to diffuse
36
What happens during depolarisation
Voltage gated Na+ ion channels open This leads to Na+ ion flooding down the conc gradient into the axon So the inside of axon becomes positive
37
What happens during repolarisation
Na+ voltage gated channels close K+ voltage gated channels open and K+ ions flood down conc gradient of axon Inside the axon returns to -70mv
38
What is repolarisation
Where the axon recovers its resting potential after the membrane reaches +40mv
39
What happens during hyperoplarisation
Too many K+ ions leave the axon so cytoplasm temporarily more negative than -70mv until the k+ vgc ions close
40
What is the all or nothing principal
Action potential can only be generated if the stimulus reaches a certain threshold intensity and below the threshold action potential won't be reached
41
How does size change between action potentials
It doesn't all action potentials are the same size
42
How does a strong stimulus differ in production in action potential to a weaker stimulus
A strong stimulus produces more action potentials and is likely to cause action potential in more neurones
43
What is a refractory period
for a brief time after an impulse where The k+ channels close and so do the Na+ channels No matter what stimulus is applied they will not reopen to allow Na+ in This means no impulse can pass
44
What is the importance of the refractory period
No overlapping of potentials Ensures a.p only travels in one direction Limits the number of a.ps
45
What are the effects of myelination
The myelin sheath greatly increases the speed at which impulses are conducted over the axon
46
How does the myelin sheath help to increase speed
Insulates the axon so depolarisation can only occur at nodes of Ranvier and the impulse jumps from node to node
47
How are unmyelinated sheaths slower
The entire axon membrane is exposed and it all must undergo depolarisation so impulse conduction is slower
48
What are the effects of the diameter of an axon
Impulse will be conducted at a higher speed along neurones with thicker axons they have a greater Surface area over which diffusion of ions can occur
49
What are the effects of temperature on an axon
Doesn't usual affect the speed of nerve impulses However colder conditions can slow down the conduction of nerve impulses
50
The blink reflex is caused by what type of stimuli (7)
Pressure light touch temperature chemicals smell noise
51
What event starts depolarisation
Sodium channels open
52
Why would a hydrophobic molecule be able to pass into neurones
they are lipid soluble
53
Why might damage to myelin sheaths lead to problems controlling muscle contraction
Causes hyperpolarisation or preventing depolarisation
54
Why would a myelinated axon conduct impulses faster than a non-myelinated axon
In myelinated action potential only at nodes so impulses jump from node to node and action potential does not travel whole length
55
Give 3 factors that effect the speed of nerve impulses
Temperature Axon diameter Myelination
56
Why is it important that a neurotransmitter is transported back out of synapses?
If it isn't removed it will keep binding to receptors This means it will keep causing depolarisaion in post synaptic membranes
57
Explain how resting potential is reestablished
Active transport of sodium out of axon and Active transport of potassium into axon
58
Describe how resting potential is established in an axon
Pump Na+ ions out of axon and diffusion of K+ into axon Little diffusion of Na+ into axon
59
Why can Na+ and K+ only pass through the axon membrane through proteins
Can not pass through phospholipid bilayer as they are charged
60
Describe the sequence of events leading to the acetylcholine and its binding to the postsynaptic membrane
calcium ions enter synaptic knob Vesicles fuse with membrane Acetylcholine diffuses across synaptic cleft Binds to receptors
61
Explain the importance of reflex actions
Automatic/involuntary Reducing damage to tissues Posture and balance Escaping from predators Finding food
62
Describe the sequence of events which allows information to pass from one neurone to the next neurone across a cholinergic synapse
Impulse causes calcium ions to enter axon Vesicles fuse with presynaptic membrane This releases acetylcholine Acetylcholine diffuses across the synaptic cleft where it binds with receptors on the postsynaptic membrane Sodium ions enter neurone Depolarisation of postsynaptic membrane If above the threshold action potential is produced
63
What are agonist drugs
Drugs that stimulate a nervous system
64
What are antagonist drugs
Drugs that inhibit a nervous system
65
Describe temporal summation
A number of impulses arriving in quick succession
66
Describe summation
A number of synaptic neurons synapsing with one Post synaptic neuron Their effects add up together
67
What does unidirectionally synapse mean
Synapses can only pass information in one direction
68
Describe inhibitory ion channel synapses
Neurotransmitters released bind to chloride ions channel protein on the Post synaptic membrane Chloride ions move into Post synaptic membrane by facilitated diffusion The binding of the neurotransmitter causes openings of nearby K+ vgc K+ move out of the Post synaptic membrane neuron into the synapse Inside of he Post synaptic neurone is more negative making that the threshold is harder to reach
69
Name types of receptors in humans
Photoreceptors Mechanoreceptors Chemoreceptors Thermoreceptors
70
Describe photoreceptors
Detect light and other forms of E.M
71
Desribe mechanoreceptors
Detect movements, pressure, tension, gravity and sound waves
72
Describe chemoreceptors
Detect specific chemicals
73

Topic 6 Organisms response to change (5 decks)

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