B3.1 Nervous System Flashcards

1
Q

Function of nervous system

A

To detect changes in the environment and respond to these changes to maintain homeostasis

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2
Q

Name given to change in environment

A

Stimulus

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3
Q

Name group of cells responsible for detecting a stimulus

A

Sensory receptors

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4
Q

Where are receptor cells generally found

A

Sense organs

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5
Q

Some common examples of sense organs and their stimulus (5 senses)

A

Eye - Light
Tongue - Chemical tastes (in food and drink)
Nose - Chemical smells (in the air)
Skin - Temperature, pressure and pain
Ears - Sound

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6
Q

Name given to cells that carry out the response

A

Effectors

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7
Q

2 types of effectors giving an example response for each

A

Muscles - respond by contracting

Glands - respond by secretions

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8
Q

2 key components of the nervous system

A

Central nervous system (CNS)
Peripheral nervous system (PNS)

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9
Q

Key components of nervous system

A

Brain
Spinal cord
Nerves

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10
Q

Central nervous system

A

Composed of brain and spinal cord
Brain is only involved in voluntary actions
Involved in both voluntary and involuntary actions

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11
Q

Peripheral nervous system

A

PNS is composed of nerve cells that carry information to and from CNS in spinal cord
Invovled in both voluntary and involuntary actions

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12
Q

3 main types of nerve cell including their pathway

A

Sensory – neurones that carry information as electrical impluses from receptors in the sense organs to CNS
Relay – neurones that carry electrical impulses from sensory neurones to motor neurones, found in CNS
Motor – neurones that carry electrical impulses from CNS to effectors

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13
Q

Direction of impulse

A

Direction in which a signal travels through a nerve

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14
Q

Type of signal is transmited by nervous system

A

Electrical

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15
Q

Difference between nerve and neurone

A

Neurones = specialised cells that conduct electrical impulses through body
Nerve = bundle of many nerve fibres enclosed within a protective sheath
Nerve fibres = long axons of neurones together with any associated tissues

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16
Q

Pathway for a ‘voluntary action’

A

Stimulus → Receptor cells → Sensory neurone → Spinal cord → Brain → Spinal cord → Motor neurone → Effector → Response

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17
Q

What is menat by a ‘coordinated’ response

A

Ability of brain to process information from many sensory receptors simultaneously and send a series impulses to different parts of the body to produce the required actions

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18
Q

Direction of impulse through neurone with reference to labels

. Y ]1 3
>-★-<===-<-< ]4
I
2

A

Impulse travels from dendrites (1) through neurone to axon terminals (4)

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19
Q

Parts of a motor neurone

. Y ]1 3 .
>-★-<===-<-< ]4
I
2

A

1) Dendrites
2) Cell body
3) Axon
4) Axon terminals

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20
Q

Cell type that surrounds axon of certain neurones and their purpose

A

Schwann’s cells
Collectively they form MYELIN SHEATH - insulates axon and increase speed of transmission
Gaps between these cells = nodes of Ranvier

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21
Q

Synapse

A

Area between axon terminals of pre-synaptic (previous) neurone, and dendrites of post-synaptic (next) neurone
Synapse aka synaptic cleft

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22
Q

Name to mode of transmission within a synaptic cleft / synapse

A

Chemical

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23
Q

Pathway of transmision from axon terminals pre-synaptic neurone to post-synaptic neurone

A

Electrical signal arrives at axon terminals of the pre-synaptic neurone.
Vesicles containing neurotransmitters stimulated.
Neurotransmitters difuse out of pre-synaptic neurone into synaptic cleft.
Neurotransmitters difuse across synaptic cleft.
Neurotransmitters bind to receptors dendrites of the post-synaptic neurone
Electrical signal triggered by neurotransmitters in the post-synaptic neurone
e.g electrical → chemical → electrical

Simple:
The neurotransmitters bind to receptors on the next neurone.
Neurotransmitters diffuse across the synapse.
The presence of the neurotransmitter causes the production of an electrical impulse in the next neurone.

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24
Q

Organelle in abundance in neurones

A

Mitochondria to provide energy

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25
Q

Difference between voluntary and reflex action

A

Voluntary actions involve conscious thought
Reflex actions are automatic (involuntary) reactions, they are unconscious missing out the brain, occuring without thinking

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26
Q

Reflex that protects retina in changing light intensities

A

Pupil reflex

27
Q

How your body responds to stepping on a sharp object from stimulus to response

A

Stimulus - stepping on sharp object
Receptor - pressure receptors in the skin
Electrical impulse transmitted through sensory neurone to spinal cord
Electrical impulse transmitted through motor neurone to muscles in thigh of the leg
Effector - the muscles in thigh of the leg lift the leg to move away from the object in response

28
Q

Cornea

A

Transparent coating on the front of the eye
Protects eye
Reflects light entering eye

29
Q

Conjunctiva

A

Protective membrane continuous with eyelids across front of visible sclera
Protects from infection by stopping pathogens entering eye

30
Q

Pupil

A

Central hole in iris
Allows light to enter eye

31
Q

Iris

A

Coloured ring of muscle
Alters pupil size by contracting or relaxing

32
Q

Lens

A

Transparent BICONVEX lens
Focuses light clearly onto retina

33
Q

Suspensory ligaments

A

Work together with the cilary body to control the shape of lens by becoming taught or slack
Connect the ciliary body to lens

When ciliary muscles contract - suspensory ligaments relax - lens goes fat
When ciliary muscles relax - suspensory ligaments are pulled taught - lens gets thinner

34
Q

Retina

A

Contains 2 types of photoreceptor cells rods and cones
Photoreceptor cells produce a nervous impulse when exposed to light

35
Q

Optic nerve

A

Nervous tissue
Carries nerve impulse / transmits visual information from retina to brain

36
Q

Parts of eye

A

Sclera – Tough outer wall, ‘white’
Conjunctiva – membrane over eye
Cornea – transparent outer layer
Lens – focuses light
Pupil – hole in the centre of the iris, through which light passes, allowing light into eye
Aqueous humor - nutrients & pressure
Iris – controls diameter of pupil via circular and radial muscles and the quantity of light reaching the retina.
Vitreous humor – pressure and shape.
Choroid – nutrients & waste
Fovea – blind spot
Optic nerve head – nerves exit
Optic nerve – impulses to eye
Retina – contains rod & cone cells
ciliary muscles are a ring of smooth muscle that changes the shape of the lens to focus light.
suspensory ligaments are a ring of fibres that connect ciliary muscles to the lens

37
Q

Aqueous humour

A

Fluid between cornea and lens that provides nutrients for lens and cornea that have no blood supply and helps maintain pressure

38
Q

Vitreous humor

A

TRANSPARENT, COLOURLESS, gel-like substance that fills space between LENS and RETINA within the eye and helps maintain pressure and shape

39
Q

2 types of photo receptor cell in eye

A

Rods - respond to light and allow you to see in low light levels
Cones - respond to red, blue and green light to allow you to see in different colours

40
Q

How circular and radial muscles control the size of pupil

A

In DIM light radial muscles CONTRACT and circular muscles RELAX to make pupil become larger to allow more light to reach retina

In BRIGHT light radial muscles RELAX and circular muscles CONTRACT to make pupil become smaller and protect retina

41
Q

How suspensory ligaments and cilliary muscles control shape of lens

A

Nearby object - cilliary muscle contracts down towards the lens - suspensory muscles to become slack - causes the lens to fatten and become more convex - increasing refraction of light passing through lens

Far object - cilliary muscle relaxes away from lens - pulls suspensory muscles taut - causes lens to be pulled thiner and become less convex - decreases refraction of the light passing through

42
Q

Accommodation (biology)

A

Process of focusing incoming light by the eye

43
Q

Myopia

A

Shortsightedness
Can see near objects clearly,
but they cannot focus properly on distant objects

Eyeball elongated = distance the lens to retina too far
Lens too thick and curved = light is refracted to much and focuses short

Corrected with CONCAVE lens in front of eye

44
Q

Hyperopia

A

Longsightedness - length of eyeball too short
Loss of elasticity in the lens = cannot become thick enough to focus (often age-related)

Can see far objects clearly, but they cannot focus properly on near objects
Lens focusses converge of light rays behind retina
Corrected with CONVEX lens

45
Q

Brain

A

Process information collected by receptor cells about changes in internal and external environment
Recieves and processes information from hormonal system
Produces a coordinated response for all of the information it recieves
Speeds up neuronal communication by providing a centralised control centre

46
Q

Approximately how many neurones does an adult brain contain

A

86 billion

47
Q

How the delicate nervous tissue of the brain is protected

A

Protective membranes around the brain
Skull

48
Q

Cerebrum

A

LARGEST part of brain, made of cerebral cortex (the 2 folded hemispheres)
Controls CONSCIOUSNESS, LANGUAGE, THOUGHT, PERCEPTION, MEMORY, ATTENTION

Receives input from sensory systems of spinal cord and from other parts of brain, and integrates these inputs to fine-tune motor activity

Several structures underneath the cerebrum, including hippocampus which is involved with memory

49
Q

Cerebellum

A

SECOND LARGEST part of brain
Does not initiate movement but contributes to coordination & precision
Cerebellar damage produces disorders in movement, balance, posture, and motor learning in humans

50
Q

Medulla oblongata

A

Part of brainstem, involved with UNCONSCIOUS ACTIVITIES - controls:
HEARTBEAT
GUT
RATE + DEPTH OF BREATHING
VOMITING
BLOOD PRESSURE

51
Q

Pituitary gland

A

‘Pea-sized’ gland often referred to as the ‘master gland’ which stores and releases hormones

Secretes hormones that act both directly and indirectly

52
Q

Hypothalamus

A

Controls ‘thermo’ and ‘osmo’ regulation
Interacts with pituitary gland - links nervous system to hormonal system

53
Q

How can you investigate brain function

A

Work out what different areas of the brain do based on what happens when those areas were damaged e.g. stroke victims provide evidence to map the brain
Stimulation with electrodes internally or externally to electrically stimulate the brain while the patient is awake
Computed tomography (CT) scans use X-rays to create 3D images of the brain to detect abnormalities
Functional magnetic resonance imaging (fMRI) uses powerful electromagnets to generate real-time images of brain

54
Q

Who was involved in an explosion resulting in and iron pole going through his skull in 1848 providing some of the first evidence of the consequences of brain damage?

A

Phineas Gage (1823-1860)

Pole removed parts of cerebral cortex involved with social inhibition
He suffered behavioural changes

55
Q

Henry Gustav Molaison (1926-2008)

A

Had large parts of his hippocampus removed on both sides of his brain to try and treat his epilepsy

After sugery, Molaison suffered profound memory loss
He was able to learn new motor skills after the surgery but not able to learning new information
He only remembered past events

56
Q

Victor Leborgne (1824-1880)

A

Nicknamed “Tan” because that was the only word he could say

Brain studied by Paul Broca

57
Q

Possible causes of nervous system damage

A

Injury
Disease
Inheritance
Toxins

58
Q

Possible effects of PNS damage

A

Inability to detect pain
Numbness
Loss of coordination

59
Q

Difference between PNS injury and CNS injury

A

PNS - limited abiliy to regenerate with minor nerve damage often self healing
CNS - cannot regenergate

60
Q

Effects of CNS damage

A

Loss of control of body system
Partial or complete paralysis
Memory loss or processing difficulties

61
Q

Why it is almost impossible to repair damage to the spinal cord

A

Consists of 31 pairs of nerves, each of which contain many nerve fibre
Only 1.5 cm in diameter therefore it is very difficult to identify and repair an individual nerve

62
Q

Treatments available for damage to brain

A

Radiotherapy & chemotherapy for tumours
Surgery to remove damaged brain tissue
Deep brain stimulation to stimulate brain function

63
Q

Diagram of synapse in a reflex arc

A

. , 1: relay neurone
,
,,,.
,o,.o. 2: vesicle containing neurotransmitter acetylcholine
3: synapse
,,, *,,, 4: motor neurone
.,,…….,,
,,,,
,,

64
Q

What happens when ciliary muscles contract

A

Lens becomes fatter - can focus on near obiects