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Biology GCSE > B3.1 - The Nervous System > Flashcards

B3.1 - The Nervous System Flashcards

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1
Q

What is your nervous system?

A

Something that detects changes in the environment and sends this information to your brain to decide an appropriate response.

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2
Q

3 basic stages of a nervous response.

A

Stimulus - change in environment
Sensory receptors - cells that detect the stimulus
Effector - muscles or glands that respond

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3
Q

What do receptor cells detect?

A
  • They are found in different organs.
  • They detect different stimuli and change it into electrical impulses that travel across neurones (nerve cells) to your CNS.
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4
Q

Examples of receptor cells.

A

Light - eye is the organ
Taste - tongue is the organ
Pressure/Temperature - skin is the organ

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5
Q

What is your central nervous system?

A
  • Brain and spinal chord.
  • Made of delicate nervous tissue protected by bones.
  • Skull protects the brain and vertebral column protects the spinal chord.
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6
Q

Describe the path of an impulse in a coordinated response.

A

Stimulus > receptor cells > sensory neurone > spinal chord > brain > spinal chord > motor neurone > effector > response.

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7
Q

What are the three types of neurone and their functions?

A

Sensory neurone - carry impulse from receptor cells to CNS
Relay neurone - carry impulse from sensory neurone to motor neuron
Motor neurone - carry impulse from CNS to effector.

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8
Q

What is a coordinated response?

A
  • Brain receives lots of information from sensory neurones, the brain processes all this information and forms a coordinated response.
  • Series of impulses being sent to different effectors producing an action.
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9
Q

Features of a neurone

A

Dendrite - branched endings of the cell that join one neurone to another.
Axon (long bit in the middle of a neurone) surrounded by myelin sheath - myelin sheath is an electrical insulator, speeding up the electrical impulse.

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10
Q

How is information passed from one neurone to another?

A
  • Electrical impulses are passed along the axon.
  • The connection between two neurones = synapse.
  • Electrical impulse triggers release of the transmitter chemicals, diffused across the synaptic cleft (gap).
  • Chemicals bind to receptor molecules of the next neurone.
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11
Q

What is a reflex action?

A

Involuntary (automatic) reactions that occur without you thinking about them. The process misses out your brain. Reaction is 0.2 seconds compared to a voluntary action of 0.7 seconds.

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12
Q

Explain the nerve pathway an impulse follows in a reflex action. (Reflex action)

A

MISSES OUT THE BRAIN PART OF THE CNS

Stimulus > receptor cells > sensory neurone > spinal chord (relay neurone) > motor neurone > effector > response

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13
Q

What is the purpose of a reflex action?

A

They have a protective role in ensuring you are protected in situations of danger.

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14
Q

Describe the cornea, pupil and iris with their functions.

A

Cornea - transparent coating on the front of the eye.
- Refracts light entering the eye

Pupil - centre hole in the iris.
- Allows light to enter the eye

Iris - coloured ring of muscle tissue
- controls how much light enters the eye by contracting or relaxing

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15
Q

Describe the lens, ciliary body/muscle and suspensory ligaments with their functions.

A

Lens - transparent biconvex lens
- Focuses light clearly onto the retina

Ciliary body - muscle tissue containing the ciliary muscles that are attached to the suspensory ligaments.
- Alter the shape of the lens

Suspensory ligaments - connect the ciliary muscles to the lens.

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16
Q

What does the optic nerve do?

A

It is nervous tissue which carries nerve impulses to the brain.

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17
Q

Describe the retina and its components.

A

The retina is the light sensitive part of the eye and has photoreceptor cells called rods and cones

18
Q

What are the photoreceptor cells in your retina called and what do they do?

A

Rods - allow you to see in the dark by responding to light but don’t respond to different colour

Cones - respond to different colours but not light, e.g. different cone cells respond to red, green and blue light.

19
Q

How are close images formed?

A
  • Cornea refracts the light and it passes through the pupil
  • Your ciliary muscles contract making your lens convex (fatter) focusing the light onto your retina, the impulse travels from your retina to your optic nerve and your brain interprets an image.
20
Q

How are distant images formed?

A
  • Cornea refracts the light and it passes through the pupil
  • Your ciliary muscles relax making your lens less convex (thinner) focusing the light (refracted less) onto your retina, the impulse travels from your retina to your optic nerve and your brain interprets an image.
21
Q

What does it mean if someone is short-sighted?

A

Myopia. Distant objects seem blurry. Unable to focus on distant objects.

22
Q

What does it mean if someone is long-sighted?

A

Hyperopia. Unable to focus on near objects.

23
Q

What causes short sightedness?

A
  • Either the eyeball is too long, or the lens is too strong and light is refracted too much.
  • Distant objects are brought into focus in front of the retina. (Light rays meet in front of the retina)
24
Q

What causes long sightedness?

A
  • Either the eyeball is too short, or the lens is too weak and the light is not refracted enough.
  • Near objects are brought into focus behind the retina. (Light rays meet beyond the retina)
25
Q

How do you correct being short sighted?

A

Use concave lens’ which bend the light outwards before they enter the eye so that they don’t meet in front of the retina, instead they meet on the retina.

26
Q

How do you correct being long sighted?

A

Use convex (fatter) lenses to bend the light rays inwards before entering the eye so they meet at the retina and not beyond it.

27
Q

What does it mean to be colour blind?

A
  • Genetically inherited, usually in males
  • If you are red green colour blind then your red and green cones in the retina do not work properly and you cannot distinguish the difference.
28
Q

5 main areas of the brain.

A

Cerebrum, cerebellum, medulla, hypothalamus, pituitary gland.

29
Q

Function of the cerebrum.

A

Outer wrinkly part of the brain

- Controls complex behaviour such as language, memory, learning, personality and complex thought.

30
Q

Function of the cerebellum.

A

Controls muscle coordination, posture, balance and involuntary movement.

31
Q

Function of the medulla.

A

Controls automatic functions such as heart rate and breathing rate.

32
Q

Function of the hypothalamus.

A

Regulates body temperature and water balance.

33
Q

Function of the pituitary gland.

A

Stores and releases hormones.

34
Q

Difficulties/issues with studying the brain.

A
  • If a persons brain is damaged, unethical to study it as they can’t give consent.
  • Many case studies and brains are needed to gather reliable information.
  • Several areas of the brain are involved in functions.
  • Interpreting results of fMRI scanners is difficult because we can’t be sure if the brain would act the same without the machine.
35
Q

What is the PNS?

A

Peripheral nervous system
- All the neurones that connect the CNs to the rest of the body.
e.g. Sensory neurones - nerve impulses from receptor cells to CNS
Motor neurone - nerve impulses from CNS to effector

36
Q

What can cause nervous system damage?

A

Injury
Disease
Genetic condition - Huntingtons disease
Injecting toxic substances.

37
Q

What does damage to the PNS lead to?

A
  • Numbness
  • Loss of coordination
  • Inability to detect pain
    as it affects the sensory and motor neurones.
38
Q

Curing PNS damage?

A
  • Limited ability to regenerate unless it is minor nerve damage, self heals in that case.
  • Surgery can repair sever damage, graft nervous tissue over damaged tissue to restore electrical conduction.
39
Q

What does damage to the CNS lead to?

A
  • Loss of control body systems
  • Partial or complete paralysis
  • Memory loss or processing difficulty.
40
Q

Why is it difficult to repair CNS damage?

A
  • Cannot regenerate
  • Has 31 pairs of nerves with many nerve fibres, identifying each one and repairing it without damaging others is impossible.
  • Difficult to diagnose. Can use MRI or CT scans.
41
Q

Treatment available for nervous system damage

A

Chemo or radiotherapy - treat brain tumour
Surgery - remove damaged tissue
Deep brain stimulation - insert electrodes to stimulate brain functions.

Biology GCSE (6 decks)

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