N5 Biology control and communication

Function of endocrine glands

release hormones into the bloodstream

What are hormones?

A chemical messenger released into the bloodstream

How are only the target tissues affected by hormones

A target tissue has cells with complementary receptor proteins which are specific to a hormone

What are the three main endocrine glands?

The pancreas

Ovaries (female)

Testes (male)

Describe how the body responds to an increase in glucose

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.

Describe how the body responds to a decrease in glucose

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!

Describe two responses to a stimulus

A response can be a rapid action from a muscle

Or

a slower response from a gland by the release of a chemical.

Describe the components of the nervous system including the CNS

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.

Describe the structure and function of the brain

A- Cerebrum - controls conscious thought and actions, memories and personality

B- Medulla - controls heart rate and breathing rate

C- Cerebellum - controls balance, movement and coordination

State the definition of a target tissue.

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

Name and describe the function of neurons

• 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)

State the order of the reflex arc

The receptor detects a stimulus.

The message travels along a sensory neuron.

It is then passed along an interneuron.

The message travels down a motor neuron.

An effector, which is a muscle or a gland, carries out a response.

A reflex response protects the body from harm.

State the function of a reflex

Protects the body from harm

How is information carried across neurons?

An electrical impulse is carried along the nerve fibre and into

the cell body of the neuron by a sensory fibre. The cell body

then sends the impulse out through another nerve fibre called

an axon fibre. When the impulse reaches the end of the axon

there is a small gap between the axon endings of one neuron

and the sensory fibre of the next neuron.

Definition of reflex?

A rapid, automatic and involuntary response to a stimulus that protect the

body from harm.

Function of sensory neuron

Sensory (neuron) - carries/sends message/impulse/signal from sense organ → inter neuron/CNS/spinal cord

carries impulse from sense organ → inter neuron

Function of motor neuron

Motor (neuron) - carries/sends

message/impulse/signal from CNS/Inter neuron/spinal cord> muscle/organ/effector

carries impulse from inter neuron → effector

Function of inter neuron

Inter (neuron) - carries/sends

message/impulse/signal from sensory → motor neuron/within CNS

Carries impulse → motor neuron

Function of the sensory neuron

pass information to the CNS

Name the structures within the body that release hormones

Endocrine glands produce/release hormones