Homeostasis and Response

What is homeostasis?

The maintenance of optimal conditions inside the body for enzyme activity.

What are three levels which are maintained in homeostasis?

Controlled blood glucose concentration

Controlled body temperature

Controlled water levels

What two systems are used in homeostasis?

The nervous system and the endocrine system.

What are the two components of the human nervous system?

Central Nervous system (brain and spinal cord)

Peripheral Nervous system (nerve cells)

What are the three control systems?

Receptors →cells which detect stimuli

Coordination centre →receive and process information from receptors - e.g. brain, spinal cord, pancreas

Effectors →Organs which bring responses into action to restore optimal levels - e.g. glands (releasing hormones), muscles (contracting)

What is stimuli?

Environmental changes

what is a neuron?

another name for a nerve cell.

What is a bundle of neurons called?

A nerve

what are the three main types of neurons?

Sensory

Motor

Relay

What are two nerve cell adaptations?

Has an axon

Has dendrons and dendrites

What is an axon?

Is a very long fibre - to carry messages around the whole body)

Insulated with a myelin sheath (fatty layer) - allows for quicker and more efficient transmission

What happens if the myelin sheath is damaged?

message transmission is slower

What are dendrons and dendrites?

dendrons →tiny branches

dendrites→further branches on the end of dendrons

They receive incoming impulses from other neurons

What is the function of nerve endings?

To pick up on stimulus.

List all of the features of a neuron.

Nucleus, Cytoplasm, Dendron, Dendrite, Axon, Myelin sheath, Nerve endings

What is the chain of neurons and control systems that information passes through from stimulus to effector?

stimulus →receptor →sensory neuron→coordination centre (relay neuron) →motor neuron →effector→response

What is the purpose of the relay neuron?

Allows sensory and motor neurons to communicate

How does information pass through neurons?

Through electrical impulses.

What is a receptor?

a group of specialised cells which detect stimulus and stimulate electrical impulses in response.

Which organ contains receptors?

Sense organs

What stimulus do these organs respond to?

Skin, Tongue, Nose, Eye, Ear

Skin →temp, pain, touch

tongue →chemicals (e.g. in food/drink)

nose →chemicals (e.g. in the air)

eyes→light

ear→sound, position of head

What are two examples of effectors?

Muscles (contractions)

Glands (releases hormones)