The Human Endocrine System

Year 9 ScienceStrathcona BGGS

The Endocrine SystemConsists of glands that produce

chemicals that act as messengers or signals. These chemicals are known as hormones.

Hormones are released into and carried by the blood stream.

Changes produced by hormones are generally: SlowLong term Irreversible :Growth and

Reproduction

Parts of the Endocrine System

A

B

CD

E

F

GI

H

J

K

The Pituitary GlandIs sometime called the

‘Master Gland’ as it regulates most other endocrine glands.

Releases hormones including:Growth Hormone (GH)Thyroid Stimulating

Hormone (TSH)

The Thyroid GlandIs responsible mainly

for the regulation of metabolic rate.

Major hormone:Thyroxine

The Islets of Langerhans

Are groups of cells in the pancreas

Regulates blood sugar levels

Releases hormones including:

Insulin – lowers blood glucose

levels

Glucagon – raises BGL

The Adrenals Located on top of the Kidneys

Has two layersThe outer Cortex

Which releases aldosterone and cortisol.

The inner MedullaReleases adrenaline

and noradrenaline - key hormones of the stress response

The OvariesRelease the female sex

hormones:Estrogen (Oestrogen)

stimulates the development of female secondary sexual characteristics

involved in monthly preparation for pregnancy

Progesteronestimulates the growth of

mammary glandsprepares the uterus for

pregnancy

The TestesSecretes the male sex

Hormone: Testosterone

very important in the development of a male embryo.

stimulates the development of male secondary sexual characteristics

The Nervous System v The Endocrine SystemThe Nervous System The Endocrine SystemUses (mostly) Electrical

Messages

Fast Acting

Reversible changes

Dedicated signal system (nerves)

Uses Chemical Messages (Hormones)

Generally Slow Acting

Generally Irreversible changes

Uses Blood System to spread hormones