Hormones and Glands (AQA)

What Do these glands do?

Brain-Contains a sensitive centre called the Hypothalumus, which contains the pituitary gland.

Adrenal Glands-Produce adrenaline which prepares the body for rapid activity by increasing the heart rate and level of sugar in blood to muscles and brain.

Ovary-Produces oestrogen which cause changes at puberty and helps control the menstraul cycle.

Testes-Produces testosterone which causes changes in puberty and stimulates sperm production.

Pancreas-Produces insulin which controls blood sugar level.

Thyroid Gland-Produces thyroxine which controls the rate of metabolism.

Maintaining a constant internal environment is called homeostasis. The nervous system and hormones are responsible for this. These are some of the internal conditions that are controlled.

Water content of the body

This is controlled to protect cells by avoiding too much water entering or leaving them. Water content is controlled by water loss from

• the lungs when we exhale
• the skin by sweating
• the body, in urine produced by the kidneys

Too Little

1) Hypothalamus detects too little water in the blood. 2) Pituitary gland releases ADH. 3) Kidneys maintain blood water level. 4) So less water is lost in urine (urine more concentrated). 5) Blood water level returns to normal.

Too Much

1) Hypothalamus detects too much water in the blood. 2) Pituitary gland releases less ADH. 3) Kidneys reduce blood water level. 4) So more water reaches bladder (urine more dilute). 5) Blood water levels return to normal.