homeostasis

What is homeostasis?

Homeostasis is the maintenance of a constant internal environment.

What does homeostasis do?

Homeostasis maintains optimal conditions for enzyme action and all cell functions.

What does homeostasis need to control in the human body?

• blood glucose concentration
• body temperature
• water levels.
These automatic control systems may involve nervous responses or chemical responses.

What do the control systems include?

• receptors,
• coordination centres
• effectors

How does the nervous system work? (short)

stimulus > receptor > sensory neuron > coordinator (relay neurone) > motor neuron > effector > response

How fast are reflex actions?

Reflex actions are automatic and rapid; they do not involve the conscious part of the brain.

What is the endocrine system composed of?

The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream.

What does the blood do to the hormones?

The blood carries the hormone to a target organ where it produces an effect.

How is the endocrine different to the nervous system in terms of speed?

Compared to the nervous system the effects are slower but long-lasting

What is the pituitary gland?

The pituitary gland in the brain is a 'master gland' which secretes several hormones into the blood in response to body conditions.

What do the hormones from the pituitary glands do?

These hormones act on other glands to stimulate other hormones to be released

What body parts are important to the endocrine system?

• pituitary gland
• pancreas
• thyroid
• adrenal gland
• ovary
• testes.

What is adrenaline?

It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for 'flight or fight'.

Where is adrenaline produced?

Adrenaline is produced by the adrenal glands ( above the kidneys) in times of fear or stress.

What is thyroxine?

stimulates the basal metabolic rate.

What is thyroxine important for?

growth and development.

How is thyroxine levels controlled?

by negative feedback.