B10 - The human nervous system

Question 1

What is homeostasis?

Answer 1

The maintenance and control of the body’s internal environment to maintain optimum conditions to respond to changes in the environments

Question 2

Examples of internal conditions that need to be controlled (4)

Answer 2

• pH
• blood glucose conc.
• water
• temperature

Question 3

What does the nervous system allow

Answer 3

Allows humans to react to their surroundings and coordinate their behaviour

Question 4

What are receptors

Answer 4

Cells that detect changes (stimuli) in the internal and external environments

Question 5

What are coordiantion centres

Answer 5

Areas that receive and process info from the receptors. They also send signals and coordinate responses

Question 6

Examples of coordination centres

Answer 6

Brain, spinal cord, pancreas

Question 7

What are effectors

Answer 7

Muscles or glands that carry out a response to a stimulus

Question 8

What is a reflex and why are they important

Answer 8

They are automatic and rapid as they dont involve the conscious part of the brain.

This allows the body to avoid harm

Question 9

How is a signal sent across a synapse?

Answer 9

• electrical impulse triggers release of chemical neurotransmitters
• These diffuse across the synapse
• Once across, they set up another electrical impulse

Question 10

Give a detailed explanation of a reflex arc

Answer 10

• Receptor detecs stimulus and sets up & sends an impulse along the sensory neurone to the spinal cord
• Sensory neurone is synapsed with the relay neurone which is synapsed with the motor neurone
  -The electrical impulse in the neurone triggers the release and diffusion of chemical neutrotransmitters which set up another electrical imuplse in the next neurone
• Impulse travels along motor neurone to effector which carries out a response

Question 11

What does the cerebral cortex control?

Answer 11

Consciousness, language, intelligence and memory

Question 12

What does the cerebellum control

Answer 12

Controls balance and muscle activity

Question 13

What does the medulla control?

Answer 13

Unconscious activities e.g. breathing and heartbeat

Question 14

What does the hypothalamus control

Answer 14

Body temperature and release of some hormones (e.g. ADH) from the pituitary gland

Question 15

What does the pituitary gland control

Answer 15

Known as the master gland, it controls many body systems by producing and storing many hormones

Question 16

Problems with the brain that make brain issues hard to resolve

Answer 16

• The brain is delicate
• Not everything isknown about the brain
• Blood brain barrier makes drug delivery harder
• Surgery could cause unintended damage

Question 17

Outline what happens in your eyes when a bright light is switched on

Answer 17

• Circular muscles contract
• Radial muscles relax
• Pupil constrics
• Less light enters eyes

Question 18

Outline what happens to your eyes when entering a dark area

Answer 18

• Circular muscles relax
• Radial muscles contract
• Pupil dilates
• More light enters eyes

Question 19

What is accomodation

Answer 19

The process of changing the shape of the lens to focus on near or distant objects

Question 20

Describe the process of accomodation for distant objects

Answer 20

• Ciliary muscles relax
• Suspensory ligaments taught
• Lens is flat and thin as less refraction is required

Question 21

Describe the process of accomodation for close objects

Answer 21

• Ciliary muscles contract
• Suspensory ligaments loosen
• Lens is thicker and more curved (convex)

This is due to light rays from a close object being divergent meaning the lens has to refract light more

Question 22

How is myopia caused and where is the image formed

Answer 22

• Eyeball is too long or lens is too curved
• Image is ‘formed’ infront of the retina

Question 23

How is myopia fixed

Answer 23

Glasses with concae lenses

Question 24

How is hyperopia caused and where is the image formed

Answer 24

• Lens is too flat or eyeball is too short
• The image is ‘formed’ behind the retina

Question 25

How is hyperopia fixed?

Answer 25

Glasses with convex lenses

Question 26

Why are contact lenses a common fix for eye problems

Advantages of contacts basically

Answer 26

• Versatile - can be soft + disposable or hard + long lasting
• Offers freedom

Question 27

How does laser eye surgery fix myopia and hyperopia

Answer 27

• Myopia - reduces thickness of cornea so less refraction
• Hyperopia - reshapes cornea to increase refraction