B10 The Human Nervous System

Question 1

What are the 2 main parts of the human nervous system?

Answer 1

The spinal chord and the CNS (central nervous system)

Question 2

What does the CNS consist of?

Answer 2

• The brain

- Neurones

Question 3

Which part of the brain is responsible for language, memory and consciousness?

Answer 3

The Cerebral cortex

Question 4

Which part of the brain is responsible for the heart rate and breathing rate?

Answer 4

The Medulla

Question 5

Which part of the brain is responsible for movement coordination and balance?

Answer 5

The Cerebellum

Question 6

Why is it difficult to study the brain and treat brain damage?

Answer 6

• The brain’s protected by the skull, making it hard to
  access
• The structures of the brain are extremely complex -
  it’s difficult to identify which part performs which
  function
• The brain is delicate and easy to damage

Question 7

What are the 3 ways scientists use to investigate the brain?

Answer 7

• Study patients with brain damage - by identifying
  where the damage has occurred, they can link it to its
  function
• Electrically stimulate the brain, and look at the effects
  on the persons behaviour, narrowing down specific
  regions to their functions
• Use MRI scanning to see which parts of the brain are active while performing different activities

Question 8

What type of organ is the eye?

Answer 8

A sense organ

Question 9

Describe how the eye detects light

Answer 9

Light rays first travel through the transparent front of the eye - the Cornea, then through the pupil, then through the lens, which focuses the light rays onto the back of the eye - the Retina. The Retina contains receptor cells which detect light intensity and colour, and send electrical impulses down the Optic nerve

Question 10

Where is the Cornea located and what is it’s function?

Answer 10

At the front of the eye, and it’s job is to begin focusing light rays

Question 11

What is the pupil

Answer 11

The space in the centre of the iris which light passes through

Question 12

What is the function of the lens?

Answer 12

To focus light rays onto the back of the eye

Question 13

What is the purpose of the Sclera?

Answer 13

It protects the eye

Question 14

What 3 components work together to enable accommodation?

Answer 14

• The ciliary muscles
• The suspensory ligaments
• The lens

Question 15

What’s the job of the Iris?

Answer 15

To control the amount of light that enters the pupil

Question 16

Describe what would happen to a person’s pupils if they went in a dark room?

Answer 16

The drop in light intensity is sensed by light receptors in the retina, which send electrical impulses to down the optic nerve to the brain, which sends electrical impulses to the circular muscles to relax and the radial muscles to expand, causing the pupil to become larger (dilate) and let more light through the eye.

Question 17

Why is pupil dilation a reflex action?

Answer 17

It doesn’t involve the conscious part of the brain

Question 18

What happens to the pupil in the presence of a lot of light?

Answer 18

It gets smaller to reduce damage to the - circular muscles contract and radial muscles relax

Question 19

What type of focus is the Cornea?

Answer 19

A fixed focus

Question 20

How does the lens focus on near/distant objects?

Answer 20

It changes shape (accommodation)

Question 21

What is accommodation?

Answer 21

The ability of the lens to change shape to focus on near/distant objects

Question 22

What happens when the Ciliary muscles contract?

Answer 22

The suspensory ligaments loosen and the lens becomes thick, refracting light rays more strongly

Question 23

What happens when the Ciliary muscles relax?

Answer 23

The suspensory ligaments are pulled tight and the lens becomes more thin, only slightly refracting light rays

Question 24

How much does light from distant objects need to be focused?

Answer 24

A relatively small amount

Question 25

How much does light from nearby objects need to be focused?

Answer 25

A large amount

Question 26

Why is accommodation useful for the eye?

Answer 26

It helps prevent damage to the retina

Question 27

What are the general features of an automatic control system?

Answer 27

• Receptor cells - Detect changes in the environment (Stimulus)
• Coordination centre - Receives and processes information from receptor cells (e.g. Brain/Spine/Pancreas)
• Effector - A muscle or a gland which contracts/secretes a hormone to restore the optimum level

Question 28

How are messages carried from receptor cells to the CNS?

Answer 28

Through electrical impulses along neurones (nerve cells)

Question 29

What kind of neurones are connected to receptor cells?

Answer 29

Sensory neurones

Question 30

Describe the reflex arc that would occur if your hand was placed on top of a flame

Answer 30

• Stimulus (heat) detected by receptor cells in the skin, and an electrical impulse is carried down a
  sensory neurone to the CNS.
• Neurotransmitters diffuse across a synapse and onto a relay neurone where it triggers an electrical
  impulse
• Chemical diffuses again across a synapse from a relay neurone to a motor neurone, triggering another
  electrical impulse
  
  • Impulse travels across motor neurone which is connected to a muscle in the arm - causing a contraction ( pulling hand from flame)

Identify stimulus, coordination centre, effector and response pls

Question 31

What makes reflexes rapid and automatic, and what are the benefits of this?

Answer 31

They don’t involve the conscious part of the brain, and this helps to protect us from danger

Question 32

What is homeostasis?

Answer 32

The regulation of conditions inside the body/cells to maintain a stable internal environment, in response to changes in internal and external conditions

Question 33

What is the importance of homeostasis?

Answer 33

It maintains the optimum conditions for cells to function properly/enzyme action

Question 34

What is the function of a nervous system in animals?

Answer 34

It allows organisms to react to their surroundings

Question 35

Explain how laser surgery can be used to correct vision defects

Answer 35

It changes the shape of the cornea, to change how strongly light is refracted into the eye

Question 36

What new technology apart from laser surgery can offer a permanent correction for visual defects?

(What are the dangers of this)

Answer 36

Replacement lens surgery

Retina could become damaged/eye may become infected