The Endocrine System

Homeostasis

The maintenance of a constant internal environment

Hormones

Chemical messengers travelling in the bloodstream to help regulate processes in the body

FSH

Pituitary Gland

Stimulates egg development and oestrogen in ovaries

Little- growth and reproductive problems

High- infertility and peaks near menopause

Oestrogen

Ovaries

Thickens uterus lining and inhibits FSH while stimulating LH production

Little- delayed puberty, hot flushes

High- Irregular periods

LH

Pituitary gland

Causes ovulation and stimulates progesterone

Little- growth and reproductive problems

High- infertility and peaks near menopause

Progesterone

Ovaries

Maintains lining for fertilised egg and inhibits both FSH and LH

ADH

Pituitary gland

Controls the concentration of water in urine

Too much water - hypothalamus detects, Less ADH released, Less water reabsorbed by kidneys, More water lost in urine, Blood water level returns to normal

Too little water - hypothalamus detects, More ADH released, More water reabsorbed by kidneys, Less water lost in urine, Blood water level returns to normal

Little- dehydration

High- nausea and fatigue

Thyroxine

Thyroid gland

Controls how quickly energy is used

Controls metabolic rate

Little- dry skin, low libido, depression, hair loss

High- fast metabolism, rapid heart rate

Adrenaline

Adrenal gland

Prepares body for fight of flight

Causes increased heart rate and breathing rate

Stored glycogen → glucose for respiration

Pupils dilate

Increased mental awareness

Little- fatigue

High- restless, irritable, high blood pressure

Insulin

Pancreas

Lowers blood glucose levels

Blood glucose rises - levels detected by hypothalamus, Insulin releases my pancreas, Converts glucose to glycogen in liver and muscle cells, Blood glucose levels lower

Glucagon

Pancreas

Increases blood glucose levels

Low blood glucose - Hypothalamus detects levels, glucagon is released by pancreas to convert glycogen stores to glucose in liver/muscle cells, blood glucose levels return to normal

Testosterone

Testes

Controls male puberty

Little- erectile dysfunction, reduced bone mass

High-high cholesterol

Endocrine System Facts

Slower, generalised response

Hormones travel in blood stream as chemical messengers