Unit 2: Control And Communication From Achieve

Question 1

Describe 2 responses to a stimulus

Answer 1

A response can be a rapid action from a muscle, or a slower response from a gland by the release of a chemical.

Question 2

Describe the components of the nervous system including the CNS

Answer 2

The nervous system is made up of the central nervous system (CNS) and other nerves.

The CNS consists of the spinal cord and the brain.

Question 3

Describe the structure and function for the brain

Answer 3

The functions are:

Cerebrum - controls conscious thought and actions, memories and personality
Cerebellum - controls balance and movement
Medulla - controls heart rate and breathing rate

Question 4

Name and. Describe the functions for each type of neurone, describing how neurons transmit messages

Answer 4

The neurons are:

Sensory neuron - Pass information from the senses to the CNS
Inter neuron - Located in the CNS and processes information from the senses that require a response
Motor neuron - enable a response to occur at an effector (a muscle or gland)

Sensory neurons contain receptors which detect stimuli (sensory changes) and send an electrical impulse to the inter neuron and then a motor neuron to bring about a response.

Question 5

Describe a synapse

Answer 5

Neurons are connected by tiny gaps called Synapses.

Chemicals diffuse across the gap to carry the impulse from one neuron to another.

Question 6

Describe the structure and function of the reflex arc

Answer 6

1. Pressure or pain stimuli
2. Receptors in the skin
3. Sensory neuron
4. Inter neuron
5. Motor neuron
6. Effector (muscle or gland)

Rapid and protects the body from harm

Question 7

Describe a hormone and describe how target tissues recognise hormones

Answer 7

A hormone is a chemical messenger released into the bloodstream.

The target tissue contains special receptor proteins that will recognise the hormone.

The receptor proteins ensure only the target tissues are affected by the hormone.

Question 8

Describe an endocrine gland using examples

Answer 8

Endocrine glands release hormones into the bloodstream.

The three main endocrine glands are:

The pancreas
The ovaries (females)
The testes (males)

Question 9

Describe how the body responds to an increase in blood glucose

Answer 9

An increase in blood glucose leads to the following action.

The pancreas responds by releasing the hormone insulin.
Receptors in the liver detect the insulin.
In response, the liver starts to convert excess glucose into glycogen.
The blood glucose levels fall.

Question 10

Describe how the body responds to a decrease in blood glucose

Answer 10

A decrease in blood glucose leads to the following action.

The pancreas responds by releasing the hormone glucagon.
Receptors in the liver detect the glucagon.
In response the liver starts to convert glycogen back into glucose.
The blood glucose levels rise.
When the glucose is gone, it is time for glucagon!