Biology Topic 5

What is homeostasis

What is homeostasis

the regulation of the internal conditions of a cell/organism to maintain optimum conditions for function in response to internal and external changes.

What are the 3 things all control systems include ?

• Receptors(detect a stimulus)

• Coordination centre (CNS/pancreas)

• Effector (muscle/glands)

Label the diagram

A- Dendron

B- nucleus

C- axon

D- nerve endings

E- cytoplasm

F- cell membrane

How has the structure of the nervous system adapted to its function ?

Long axon so can carry messages up and down the body over long distances.

Fill in the gaps

describe the image and label the colours

Receptors detect a stimulus

Red- sensory neurone, send electric impulses to relay neurone in the CNS.

Green- relay neurone, Connect sensory neurones to motor neurones.

Blue- motor neurone, send electric impulses to effector

Effector produces a response (hand contracts away from flame)

What is a synapse ?

• a gap between 2 nerve cells

• that allows neurotransmitters to diffuse across into the next nerve cell.

What is a reflect act and why is it important?

• Automatic and rapid, do not involve conscious part of brain.

• They protect your body from harm

Label diagram and functions of each section.

Pink- cerebral cortex - (consciousness, intelligence, memory and language)

Green - cerebellum - (muscle coordination/balance)

Lilac - medulla - (unconscious activities/breathing/heartbeat)

Yellow - hypothalamus (regulating body temperature)

3 methods of studying the brain

• electrically stimulate different parts of the brain

• Studying patients with brain damage

• Brain scan (PET, CT), (MRI - different parts of the brain light up)

3 main reasons treating the brain is difficult

• it’s incased within the skull, so is hard to access

• It is very complicated, so hard to target with medications

• Mental illness/ infection

What happens when the body temperature is too high?

• Blood vessels dilate, (vasodilation)

• sweat is produced from the sweat glands

• transfers energy from the skin to the environment

What happens if the body temperature is too low?

• Blood vessels constrict (vasoconstriction)

• sweat stops and skeletal muscles contract (shiver)

• This needs respiration which transfers some energy to warm the body.

What are hormones ?

Chemical molecules release directly into the blood

What are myelin sheaths ?

• Insulation sheath that around nerves

• Made of protein and fatty substances

• Allow electrical impulses to transmitt