AQA GCSE Homeostasis

Homeostasis

The regulation of internal conditions to maintain optimum conditions in response to changes

Stimulus

A change in the environment

Receptors

Cells that detect changes in the environment

Coordination centres

Receive and process information from receptors. E.g. brain

Effectors

Muscles or glands which bring about a response

Reflex action

An automatic and rapid action

Endocrine system

Consists of glands that release hormones into the blood to get to a target organ to cause a response

Insulin

Released from the pancreas in response to high blood glucose levels and causes glucose to move from the blood into the cells. It causes glucose to be converted into glycogen for storage in the liver

Glucagon

Released from the pancreas in response to low blood glucose levels and causes glycogen to be broken down into glucose and released back into the blood

Type 1 diabetes

When the pancreas does not produce enough insulin

Type 2 diabetes

When the body cells no longer respond to insulin

Oestrogen

Released by the ovaries. Stops FSH being released and stimulates LH to be released

Follicle stimulating hormone (FSH)

Hormone released by the pituitary gland. Causes maturation of the egg in the ovary.

Lutenising hormone (LH)

Hormone released by the pituitary gland. Causes the egg to be released from the ovary.

In vitro fertilisation (IVF)

Where egg cells are fertilised outside of the body with sperm cells

Cerebral cortex

The outer part of the brain responsible for intelligence, language, memory and consciousness

Medulla

Controls unconscious activities such as heart rate and breathing rate

Cerebellum

Controls balance, co-ordination of movement and muscular activity

MRI

Brain scanning technique

Accommodation

The process of changing the shape of the lens to focus on near or distant objects

Myopia

Short-sightedness

Hyperopia

Long-sightedness

Vasodilation

When blood vessels supplying blood to the skin widen and allow more warm blood to flow near the surface of the skin, where the heat is lost to the air

Vasoconstriction

When blood vessels supplying blood to the skin narrow and allow less warm blood to flow near the surface of the skin, which reduces heat loss

Deamination

The removal of the amine group on amino acids to form urea

Selective reabsorption

When the useful substances are reabsorbed back into the blood from the kidney tubules

ADH

Hormone released from the pituitary gland which regulates the water concentration of the blood

Thyroxine

Hormone released from the thyroid gland which stimulates the basal metabolic rate