B9.1 : Nervous system

Question 1

Stimuli

Answer 1

1. A stimulus can be any change in the environment to which the body needs to respond.
2. e.g. Changes in day light, Wind speed, Temperature, Movement, Availability of food, etc
3. The stimulus/stimuli is detected by a receptor.

Question 2

Receptors

Answer 2

1. These are the cells that detect the stimuli
2. e.g. taste buds detect chemicals in your food
3. Receptors are found all over the body.
4. They detect the change in the environment and initiate (start) a signalling process within the body.
5. The signal is picked up by a neurone (nerve cell).

Question 3

Effectors

Answer 3

1. These are the organ, such as glands and muscles that bring about the responses.
2. An effector is a muscle or gland that brings about an action in response to the change in the internal or external environment.

Question 4

Responses

Answer 4

1. This is the action taken by the effector muscle/gland/organ to avoid the harmful situation
2. E.g. Muscles contracting e.g. biceps to remove your hand from a hot object.
3. e.g. Glands secreting useful substances.

Question 5

Coordination flow chart

Answer 5

1. Stimulus > Receptor > Coordination > Effector > Response

2. Information is transmitted around the body across nerves by electrical impulses.

Question 6

Human nervous system

Answer 6

1. The role of the nervous system is to protect an organism from harm by responding to changes in the internal and external environment.
2. It does this by coordinating communication between different parts of a multicellular organism.
3. Consists of the central nervous system and the peripheral nervous system

Question 7

What the human nervous system is made of

Answer 7

1. Brain
2. Spinal cord
3. The neurones

PNS and CNS

Question 8

Brain (CNS)

Answer 8

1. The brain is one of the components (parts) of the central nervous system (CNS).
2. The CNS coordinates the response of effectors.
3. Effectors are muscles or glands that act in response to a change in the internal or external environment.
4. Protected by the skull

Question 9

Spinal Cord (CNS)

Answer 9

1. The spinal cord is the other component (part) of the CNS.
2. It is also important in coordinating the response of effectors to changes in the environment.
3. Protected by the vertebral column

Question 10

The neurones (PNS)

Answer 10

1. Neurones (nerve cells) carry electrical impulses (signals) between receptors, the central nervous system (CNS) and effectors.
2. Neurones make up the peripheral nervous system.

Question 11

Reflex actions

Answer 11

1. Reflex actions allow us to respond to dangerous situations rapidly and automatically by integrating and coordinating stimuli with the responses of effectors.
2. Reflex actions do not involve conscious thought (i.e. they are involuntary actions).
3. e.g. sneezing, blinking, dropping hot objects etc
4. Involuntary actionsR

Question 12

PNS

Answer 12

1. Peripheral Nervous System

2. The peripheral nervous system refers to the nerves that connect to both the spinal cord and the brain.

Question 13

CNS

Answer 13

1. central nervous system

2. brain and spinal cord

Question 14

Categories of nerves

Answer 14

1. Part of the peripheral nervous system
2. Cranial Nerves
3. Spinal nerves

Question 15

Cranial nerves

Answer 15

These link the brain with all the organs in the head and some in the thorax and abdomen

Question 16

Spinal nerves

Answer 16

These nerves link the brain to the arms, thorax, abdomen and legs.

Question 17

Nerves

Answer 17

Nerves are made up of nerve cells or neurones surrounded by a protective fibrous tube.

Question 18

reflex arc

Answer 18

For reflex actions, the nervous system responds to stimuli (events or things) via a reflex arc

Question 19

Parts of a reflex arc

Answer 19

1. stimulus
2. receptor
3. Neurones
4. Effector
5. Response
6. Nerve Cells

Question 20

Neurones

Answer 20

1. together they make up a nerve

3 types:

1. Sensory neurone
2. Relay neurone
3. Motor neurone

Question 21

Sensory neurone

Answer 21

The sensory neurone, which receives then carries the signal in the form of an electrical impulse to the central nervous system (CNS).

Question 22

Relay neurone

Answer 22

The relay neurone (in the CNS) relays the electrical impulse from the sensory neurone to the appropriate motor neurone.

Question 23

Motor neurone

Answer 23

The motor neurone is another type of nerve cell that carries the electrical impulse from the CNS to an effector.