Topic 5: The Nervous System

Question 1

What is the central nervous system? (CNS)

Answer 1

The brain and spinal cord.

Question 2

what is the peripheral nervous system?

Answer 2

Nerve cells that carry information to or from the central nervous system.

Question 3

What are sense organs?

Answer 3

A group of specialised cells called receptor cells, which can detect changes around them, either internally or externally.

Question 4

What is a stimulus?

Answer 4

A change in environment that can be detected.

Question 5

What are 5 examples of stimuli?

Answer 5

Light, sound, chemicals, touch and temperature.

Question 6

Where does the information from sense organs travel to?

Answer 6

The brain and spinal cord (CNS) along nerve cells (neurones).

Question 7

What are nerves formed by?

Answer 7

neurones which are grouped together.

Question 8

What is an impulse?

Answer 8

The signal that travels along the neurones as an electrical current.

Question 9

What are motor neurones?

Answer 9

Specialised neurones that pass through the central nervous system toward a muscle and conducts an impulse that causes movement.

Question 10

What are sensory neurones?

Answer 10

Specialised neurons that send information from the sense organs to the CNS.

Question 11

What is reaction time?

Answer 11

When a response happens, reaction time is the time taken between the stimulus and the response.

Question 12

What is a synapse?

Answer 12

A tiny gap at the junction between two nerve cells, which nerve signals must cross.

Question 13

What is a reflex?

Answer 13

A very rapid, automatic response.

Question 14

What are 5 examples of reflexes?

Answer 14

Breathing, blinking, swallowing, sneezing and coughing.

Question 15

What is a receptor?

Answer 15

An organ that detects the stimulus.

Question 16

What does a coordinator do?

Answer 16

Detect the signal from a receptor and sends an impulse to the effector.

Question 17

What is an effector?

Answer 17

Part of the body that produces the response.

usually a muscle

Question 18

What is the response?

Answer 18

The action carried out.

Question 19

What is a receptor cell?

Answer 19

A cell that can detect stimuli inside or outside the body.

Question 20

What is a relay neurone?

Answer 20

A specialised neurone that carries nerve impulses within the central nervous system.

Question 21

What are the 5 stages of a reflex?

Answer 21

1. The stimulus is received by the receptor.
2. An impulse is sent along the sensory neurone to the spinal cord.
3. The impulse moves across a synapse to the relay neurone.
4. The relay neurone transmits the signal to the motor neurone.
5. The motor neurones stimulates the effector (the muscle) to respond.

Question 22

Why are reflexes involentary?

Answer 22

Because reflexes don’t go through the brain, they go through the spinal cord.

Question 23

What is a hormone?

Answer 23

A chemical messenger produced in glands and carried by the blood to specific organs in the body.

Question 24

What is a reflex arc?

Answer 24

The nerve pathway followed by a reflex action.

Question 25

What is a tropism?

Answer 25

A plant tropism is a growth in response to a stimulus.

Question 26

What is a phototropism?

Answer 26

A growth in response to light.

Question 27

What is a gravitropism?

Answer 27

Growth towards or away from the pull of gravity.

Question 28

What is an example of a positive tropism?

Answer 28

Plant shoots grow towards the light.

Question 29

What is an example of a negative tropism?

Answer 29

Roots grow away from light.

Question 30

What is an example of a positive gravitropism?

Answer 30

Roots of plants.

Question 31

What is an example of a negative gravitropism?

Answer 31

stems of plants.

Question 32

What are tropisms controlled by?

Answer 32

Auxin (a type of hormone).

Question 33

What is auxin?

Answer 33

A family of plant hormones.

Question 34

Where are auxin mostly made?

Answer 34

In the tips of the growing stems and roots, which are the meristems.

Question 35

What does auxin do?

Answer 35

They can diffuse to other parts of the stems or roots. Auxin change the rate of elongation in plant cells, controlling their length.

Question 36

What is an eye?

Answer 36

A sense organ which detects light and sends information about the patterns of light it receives to the brain, which builds a picture from that information.

Question 37

What is the sclera?

Answer 37

Tough white, outer layer which protects the retina.

Question 38

What is the retina?

Answer 38

Light-sensitive inner layer that has cells that detect light, some detecting coloured light.

Question 39

What is the optic nerve?

Answer 39

The cells send nerve impulses from the eye to the brain. Located at the back of the eye.

Question 40

What is the blind spot?

Answer 40

The point where the optic nerve leaves the retina so lacks receptor cells.

Question 41

What is the cornea?

Answer 41

Clear area of the sclera, it refracts light - bends it as it enters the eye.

Question 42

What is the iris?

Answer 42

The muscles which alter the size of the pupil, controlling the amount of light entering the eye.

Question 43

What is the lens's function?

Answer 43

The lens focuses light onto the retina.

Question 44

What is the choroid?

Answer 44

The pigmented middle layer with many blood vessels. It absorbs light to avoid reflection and nourishes the retina.

Question 45

What is the pupil?

Answer 45

The small hole at the centre of the iris through which light enters the eye.