B10. The human nervous system

Question 1

What is the role of the human nervous system?

Answer 1

The role of the nervous system is to allow humans to detect changes in their surroundings and coordinate responses

Question 2

What are receptor cells?

Answer 2

Receptor cells are cells that detect stimuli

Question 3

Which two organs make up the central nervous system (CNS)?

Answer 3

The CNS is made up of the brain and the spinal chord

Question 4

What are effectors?

Answer 4

Effectors are the parts of the body that respond to changes in the environment. They can be muscles or glands

Question 5

Write a flow diagram to show the pathway of an electrical impulse through the nervous system

Answer 5

stimulus ➡ receptor ➡ sensory neurone ➡ CNS ➡ motor neurone ➡ effector ➡ response

Question 6

What are reflex actions?

Answer 6

Reflect actions are automatic, rapid actions that do not involve conscious thougjt

Question 7

Why are reflex actions important?

Answer 7

Reflex actions are important because they protect the body from harm

Question 8

Write a flow diagram to represent a reflex arc

Answer 8

Stimulus ➡ receptor ➡ sensory neurone ➡ relay neurone ➡ motor neurone ➡ effector ➡ response

Question 9

What is a relay neurone?

Answer 9

A relay neurone is a neurone within the CNS that connects sensory and motor neurones

Question 10

What is the role of a motor neurone in a reflex arc?

Answer 10

Motor neurones in reflex arcs connect relay neurones with effectors

Question 11

Which factors could be chosen as independent variables when investigating the effect of a factor on reaction time?

Answer 11

Caffeine intake
Environmental factors
Time since last meal
Hours of sleep

Question 12

How can a ruler be used to measure reaction time?

Answer 12

A ruler can be used to measure reaction time by dropping it vertically from a set height with 0cm facing downwards and measuring the distance at which a volunteer catches it. The shorter the distance, this faster the reaction time

Question 13

In an investigation into the effects of caffeine on reaction time, which variables should be controlled?

Answer 13

Environmental factors
The hand being used to catch the ruler
The height from which the ruler is dropped
The time between caffeine consumption and the ruler drop test

Question 14

What is the role of the brain in the nervous system?

Answer 14

The role of the brain is to control complex behaviour, as well as regulating body functions

Question 15

What is the role of the cerebral cortex in the brain?

Answer 15

The cerebral cortex is responsible for higher brain functions such as consciousness, intelligence, memory and language

Question 16

Which body functions are regulated by the medulla in the brain?

Answer 16

Breathing
Heart rate
Digestion

Question 17

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

Answer 17

The brain is delicate
Brain function is highly complex
The functions of different brain areas are interconnected so it is difficult to study regions in insolation

Question 18

How can neuroscientists map brain function?

Answer 18

Studying patients with damage to known areas of the brain
Electrical stimulation of the brain and observation of response
MRI scanning

Question 19

Where is the sclera of the eye?

Answer 19

The white layer that forms the outside of the eyeball

Question 20

Define the term accommodation in the context of eye function

Answer 20

Accommodation is the process by which the lens of the eye changes its shape to focus on objects at different distances

Question 21

What is the role of the ciliary muscle in accommodation?

Answer 21

The ciliary muscles contract or relax to change the shape during accommodation

Question 22

What happens to the ciliary muscles, suspensory ligaments and lens when focusing on a near object?

Answer 22

The ciliary muscles contract
The suspensory ligaments loosen
This causes the lens to become thicker, increasing refraction of light for close vision

Question 23

How does the eye adapt to deal with dim light?

Answer 23

The eye adapts to deal with dim light by dilating the pupil; this allows more light to enters the eye

Question 24

Define the terms myopia and hyperopia

Answer 24

Myopia = short sightedness
Hyperopia = long sightedness

Question 25

What causes short or long sightedness?

Answer 25

Short and long sightedness are caused by inability to focus the light onto the retina

Question 26

How can short and long sightedness be treated?

Answer 26

Wearing spectacles that refract light correctly
Use of hard or soft contact lenses
Laser surgery
Replacing the lens of the eye

Question 27

Which part of the brain monitors and controls body temperature?

Answer 27

The part of the brain that monitors and controls body temperature is the thermoregulatory centre

Question 28

What is the role of receptors in the control of body temperature?

Answer 28

Receptors in the thermoregulatory centre monitor blood temperature
Receptors in the skin detect air temperature and send impulses to the thermoregulatory centre

Question 29

How does sweating increase heat loss from the body?

Answer 29

Sweating increases heat loss when sweat evaporates from the skin surface. The evaporation of sweat transfer heat energy away from the skin

Question 30

Define the term vasodilation

Answer 30

Vasodilation is a cooling mechanism in which diameter of skin arterioles increases. This increases blood flow to capillaries in the skin surface, transferring heat to the environment by radiation

Question 31

How do blood vessels and sweat glands respond to an increased body temperature

Answer 31

Sweat glands release swear which cools the skin by evaporation
Skin arterioles undergo vasodilation increase blood flow to capillaries at the surface of the skin

Question 32

How does shivering contribute towards temperature regulation?

Answer 32

Shivering occurs when body temperature is too low. The rapid muscle contractions generate heat, raising the core body temperature