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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
Difference between voluntary and reflex action
Voluntary actions involve conscious thought Reflex actions are automatic (involuntary) reactions, they are unconscious missing out the brain, occuring without thinking
26
Reflex that protects retina in changing light intensities
Pupil reflex
27
How your body responds to stepping on a sharp object from stimulus to response
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
Cornea
Transparent coating on the front of the eye Protects eye Reflects light entering eye
29
Conjunctiva
Protective membrane continuous with eyelids across front of visible sclera Protects from infection by stopping pathogens entering eye
30
Pupil
Central hole in iris Allows light to enter eye
31
Iris
Coloured ring of muscle Alters pupil size by contracting or relaxing
32
Lens
Transparent BICONVEX lens Focuses light clearly onto retina
33
Suspensory ligaments
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
Retina
Contains 2 types of photoreceptor cells rods and cones Photoreceptor cells produce a nervous impulse when exposed to light
35
Optic nerve
Nervous tissue Carries nerve impulse / transmits visual information from retina to brain
36
Parts of eye
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
Aqueous humour
Fluid between cornea and lens that provides nutrients for lens and cornea that have no blood supply and helps maintain pressure
38
Vitreous humor
TRANSPARENT, COLOURLESS, gel-like substance that fills space between LENS and RETINA within the eye and helps maintain pressure and shape
39
2 types of photo receptor cell in eye
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
How circular and radial muscles control the size of pupil
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
How suspensory ligaments and cilliary muscles control shape of lens
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
Accommodation (biology)
Process of focusing incoming light by the eye
43
Myopia
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
Hyperopia
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
Brain
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
Approximately how many neurones does an adult brain contain
86 billion
47
How the delicate nervous tissue of the brain is protected
Protective membranes around the brain Skull
48
Cerebrum
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
Cerebellum
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
Medulla oblongata
Part of brainstem, involved with UNCONSCIOUS ACTIVITIES - controls: HEARTBEAT GUT RATE + DEPTH OF BREATHING VOMITING BLOOD PRESSURE
51
Pituitary gland
‘Pea-sized’ gland often referred to as the ‘master gland’ which stores and releases hormones Secretes hormones that act both directly and indirectly
52
Hypothalamus
Controls ‘thermo’ and ‘osmo’ regulation Interacts with pituitary gland - links nervous system to hormonal system
53
How can you investigate brain function
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
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?
Phineas Gage (1823-1860) Pole removed parts of cerebral cortex involved with social inhibition He suffered behavioural changes
55
Henry Gustav Molaison (1926-2008)
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
Victor Leborgne (1824-1880)
Nicknamed “Tan” because that was the only word he could say Brain studied by Paul Broca
57
Possible causes of nervous system damage
Injury Disease Inheritance Toxins
58
Possible effects of PNS damage
Inability to detect pain Numbness Loss of coordination
59
Difference between PNS injury and CNS injury
PNS - limited abiliy to regenerate with minor nerve damage often self healing CNS - cannot regenergate
60
Effects of CNS damage
Loss of control of body system Partial or complete paralysis Memory loss or processing difficulties
61
Why it is almost impossible to repair damage to the spinal cord
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
Treatments available for damage to brain
Radiotherapy & chemotherapy for tumours Surgery to remove damaged brain tissue Deep brain stimulation to stimulate brain function
63
Diagram of synapse in a reflex arc
. , 1: relay neurone , ,,,. ,o,.o. 2: vesicle containing neurotransmitter acetylcholine 3: synapse ,,, *,,, 4: motor neurone .,,…….,, ,,,, ,,
64
What happens when ciliary muscles contract
Lens becomes fatter - can focus on near obiects

Biology OCR GCSE (16 decks)

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