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Biology MA > 2j- coordination (humans) > Flashcards

2j- coordination (humans) Flashcards

finish the stuff about neurones (look at notes) and add definitions for eye functions. pg.89 is useful

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1
Q

give a summary of the sequence of events of the coordination system

A

stimulus - receptor - coordination - effector - response

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2
Q

what is the role of the receptor?

A

to detect the stimulus by changing its energy into the electrical energy of the nerve impulses. e.g,. the eye turns light energy into nerve impulses and ear converts sound energy into nerve impulses

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3
Q

what is the biological name for a nerve cell?

A

a neurone

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4
Q

what are the impulses that travel along a neurone caused by?

A

they are caused by the movement of charged particles (ions) in and out of the neurone. they can travel at about 10-100 metres per second

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5
Q

where do the impulses from receptors go (through)?

A

they pass through nerves containing sensory neurones, until they reach the brain and spinal chord

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6
Q

what is the CNS

A

(central nervous system) - brain and spinal chord

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7
Q

what do motor neurones do?

A

transmit impulses to the muscles and glands

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8
Q

what are nerves made up of?

A

neurones

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9
Q

what is the structure of the motor neurone?

A
  • it is at one end of the fibre in the CNS
  • the cell body has fine cytoplasmic extensions which are called dendrons (they from wider extensions called dendrites) (they look like twigs/split ends)
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10
Q

what are the junctions between neurons called?

A

synapses

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11
Q

what is the fibre that carries impulses to the effector organs?

A

the axon

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12
Q

what are the branches that connect an axon to the muscle?

A

neuromuscular junction

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13
Q

what is the axon covered by? what does it do? how is it formed?

A

covered by a sheath made of a fatty material called myelin. the myelin sheath insulates the axon, preventing ‘short curcuits’ with other axons, aswell as speeding up the conduction of the impulses.
the sheath is formed by the membranes of special cells that wrap themselves around the axon as it develops

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14
Q

draw a diagram of a motor neuron

A

check on pg.87

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15
Q

draw a diagram of a sensory neuron

A

check on pg.87

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16
Q

what is the difference between a motor and a sensory neuron

A

the cell on the sensory neurone is located on a side branch of the fibre, just outside the cns

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17
Q

what is the sclera?

A

the tough outer part of the eye. it is the visible white part of the eye, however, at the front of the eye the sclera becomes a transparent window called the cornea

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18
Q

what is the cornea?

A

a transparent ‘window’ which lets light into the eye

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19
Q

what is the iris? what is its role?

A

the coloured ring of tissue behind the cornea. it controls the amount of light entering the eye, by changing the size of the pupil.

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20
Q

what is the pupil?

A

part of the eye which lets the light through. it is a hole. it is black because there is no light escaping from inside the eye

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21
Q

what is the choroid?

A

the dark layer underneath the sclera. it’s dark because it contains many pigment cells, aswell as blood vessels. the pigment stops light being reflected around the inside of the eye

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22
Q

how does the eye form an image?

A

to form an image on the retina, light needs to be bent or refracted, refraction takes place when light passes from one medium to another of a different density. In this eye this first happens at the air/cornea boundary, and again at the lens. the image on the retina is inverted and the brsin interprets the image the right way up

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23
Q

what are the two types of muscles in the iris? what do they form?

A

circular muscles which form a ring shape in the iris and the radial muscles lie like the spokes of a wheel.

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24
Q

what happens when a bright light is shone into the eye

A

the pupil is constricted as the circular muscles contract and radial muscles relax (causing the pupil TO CONSTRICT)

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25
Q

what happens when a dim light is shone into the eye

A

the pupil is constricted as the circular muscles relax and radial muscles contract (causing the pupil TO DILATE)

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26
Q

what happens if you go from bright to dim rlly quickly? What is this and exmaple of ?(eye)

A

the iris rapidly and automatically adjusts pupil size which is an example of REFLEX ACTION

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27
Q

what woudl happen to the eye if the light was too bright?

A

it could damage rods and cones - so light that is too dim would not form an image

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28
Q

what is the blind spot?

A

the area within the eye that has no rods or cones so an image can’t be formed

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29
Q

what does the brain do to resolve the image fot he blind spot?

A

the brain combines the images from both eyes, cancelling out the blind spots in both eyes

30
Q

what is accomodation?

A

the changes that take place within the eye which allow us to see objects at different distances

31
Q

what are the suspensory ligaments?

A

fibres which holds the lens in place. thye are attatched to the ciliary muscles

32
Q

what is they eye filled with? what does this do?

A

the inside is filled with a transparent watery fluid that pushes outwards on they eye. in other words, there is a slight positive pressure within the eye.

33
Q

what happens when your eye focuses on an object which is distant?

A

lens less convex (flatter), ciliary muscles relax, suspensory ligaments pulled tight.
the rays of light from the object are almost parallel when they reach the cornea. the cornea refracts the rays, but the lends does not need to refract them much more to focus the light on the retina, so it does not need to be very convex. the C muscles relax and the pressure in eye pushes it outwards on the lens, flattening it and stretching the suspensory ligaments.

34
Q

what happens when your eye focuses on an object which is near?

A

lens more convex (rounded), ciliary muscles contract, suspensory ligaments slack, the lens is more rounded
the light rays form the object spread out (diverging) when they enter the eye. in this situation, the lens has to be more convex in order to refract the rays enough to focus them on the retina. the C muscles contract, suspensory ligaments become slack and the elastic lens bulges outwards to create a more convex shape

35
Q

what is the nerve pathway of a reflex called

A

reflex arc, the arc part meaning that the pathway goes into the CNS and then back out again, in a sort of curve or arc

36
Q

what is it called when our eyes dilate/contract?

A

a reflex action

37
Q

in an iris reflex, what is the route from the stimulus to response?

A

stimulus (light intensity) - retina (receptor) - sensory neurones in optic nerve - unconscious part of brain - motor neurones in nerve to iris - iris muscles (effector) - response (change in size of pupil)

38
Q

what does the iris-pupil reflex protect the eye from?

A

damage from birght light

39
Q

what is a reflex action?

A

a rapid, automatic (or involuntary - meaning it was not started by impulses from the brain) response to a stimulus. the action often protects the body

40
Q

say you prick your skin, give me a step by step of what would happen.

A

The stimulus is detected by temperature or pain receptors in the skin. These generate impulses in sensory neurones. The impulses enter the CNS through a part of the spinal nerve called the dorsal root. In the spinal cord the sensory neurones connect by synapses with short relay neurones, which in turn connect with motor neurones. The motor neurones emerge from the spinal cord through the ventral root, and send impulses back out to the muscles of the arm. These muscles then contract, pulling the arm (and thus finger) away from the harmful stimulus.

41
Q

why is grey matter called grey matter? why is white matter called white matter?

A

The middle part of the spinal cord consists mainly of nerve cell bodies, which gives it a grey colour. This is why it is known as grey matter. The outer part of the spinal cord is called white matter, and has a whiter appearance because it contains many axons with their fatty myelin sheaths. (In the brain this is reversed - the grey matter is on the outside and the white matter in the middle of the brain.)

42
Q

how do we feel pain?

A

in the spinal cord, the reflex arc neurones also form connections called synapses with nerve cells leading to and from the brain. The brain therefore receives information about the stimulus. This is how we feel the pain.

43
Q

what are synapses?

A

a synapse is a small gap between two neurons where an electrical impulse is converted into a chemical signal and then back into an electrical signal.

44
Q

what happens at the synapse?

A
  1. An electrical impulse travels along the axon of the first neuron.
  2. When the impulse reaches the end of the axon, the neuron releases chemical messengers called neurotransmitters into the synapse.
  3. The neurotransmitters diffuse across the synapse.
  4. The neurotransmitters bind to receptor molecules on the membrane of the second neuron.
  5. The binding stimulates the second neuron to transmit an electrical impulse and an impulse is started in the second neurone.
  6. neurotransmitter broken down by enzyme from second neurone
45
Q

what can interfere with the synapses?

A

chemicals like drugs that may imitate the neurotransmitter, or block its action.

46
Q

where is the cornea? what is its function?

A

Transparent covering at the front of the eye that refracts (bends) light

47
Q

where is the iris? what is its function?

A

Muscle that controls how much light enters the pupil

48
Q

where is the lens? what is its function?

A

Transparent disc that changes shape to focus light onto the retina

49
Q

where is the optic nerve? what is its function?

A

Sensory neurone that carries electrical impulses from the eye to the brain

50
Q

where is the retina? what is its function?

A

Layer of light receptor cells that detect light intensity and colour

51
Q

what are rods and cones?

A

Rods and cones are the two types of receptor cells present in the retina of the eye

52
Q

what is special about rods vs cones?

A

Rods can detect light at low levels, so play an important role in night vision
Three different types of cones can detect light at three different wavelengths, enabling colour vision

Receptor cells that are sensitive to light, known as rods, and receptor cells that can detect colour, known as cones

53
Q

are rods and cones distributed equally?

A

Rods and cones are not distributed evenly across the retina:
Rod cells are found all over the retina, with the exception of the blind spot
Cone cells are concentrated in the fovea, the region of the eye onto which light is focused by the process of accommodation
The fovea enables the brain to form sharp, coloured images when light is effectively focused by the eye

54
Q

what is the pupil?

A

Pupil - hole that allows light to enter the eye

55
Q

what is the conjunctiva’s function?

A

Conjunctiva - a clear membrane that covers the white of the eye and the inside of the eyelids; it lubricates the eye and provides protection from external irritants

56
Q

what’s the function of ciliary muscles?

A

Ciliary muscle - a ring of muscle that contracts and relaxes to change the shape of the lens

57
Q

what is the function of the suspensory ligaments?

A

Suspensory ligaments - ligaments that connect the ciliary muscle to the lens

58
Q

what is the function of the sclera?

A

Sclera - the strong outer wall of the eyeball that helps to keep the eye in shape and provides a place of attachment for the muscles that move the eye

59
Q

what is the function of the fovea?

A

Fovea - a region of the retina with the highest density of cones (colour detecting cells) where the eye sees particularly good detail

60
Q

what is the function of the blind spot?

A

Blind spot - the point at which the optic nerve leaves the eye, where there are no receptor cells

61
Q

label the eye

A
62
Q

equation for speed

A

distance / time

63
Q

what is the function of the sheath? what is the sheath?

A

The myelin sheath is a fatty layer that surrounds the axon of a neuron. It’s made of protein and lipids.
The myelin sheath insulates the axon, which speeds up the transmission of electrical impulses. It also prevents electrical signals from leaking out of the nerve cell

64
Q

what would happen to someone if the sheath was damaged?

A

Certain diseases, such as multiple sclerosis. and poliomyelitis. The disease causes paralysis, which is often permanent., cause the myelin sheath to be destroyed. This causes damage to motor neurons which means that muscles no longer receive signals from the brain or spinal cord.

65
Q

what organelle in the cell provides the most atp?

A

mitochondria

66
Q

what is an axon?

A

An axon is a long, thin nerve fiber that carries electrical impulses away from the cell body of a neuron

67
Q

what is special about the axon and sheath? how is it made efficient?

A

Neurones have a long fibre (axon)
This means that less time is wasted transferring the impulse from one cell to another
The axon is insulated by a fatty sheath with small uninsulated sections along it (called nodes)
This means that the electrical impulse does not travel down the whole axon, but jumps from one node to the next
Their cell body contains many extensions called dendrites
This means they can connect to many other neurones and receive impulses from them, forming a network for easy communication

68
Q

what do the three types of neurones look like?

A

Sensory neurones are long and have a cell body branching off the middle of the axon
Relay neurones are short and have a small cell body at one end with many dendrites branching off it
Motor neurones are long and have a large cell body at one end with long dendrites branching off it

69
Q

what are the stages of a response to reflex?

A

The pathway through the nervous system can be summarised as follows:
stimulus → sensory neurone → relay neurone → motor neurone → effector → response

A stimulus is received by a sensory (receptor) neurone
Most receptors are specialised to detect particular stimuli
When a receptor is stimulated, it produces electrical impulses
These impulses then travel along a sensory neurone to the central nervous system (the coordinator is either the brain or the spinal cord)
In the CNS, the impulses are passed on to a relay neurone
The relay neurone links to a motor neurone, along which the impulses travel until they reach the effector
The effector is what carries out the response (the effector may be a muscle or gland)

70
Q
A

Biology MA (15 decks)

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