• Main Function:

It releases hormones into the blood to signal other cells to behave in certain ways.

It is a slow but WIDESPREAD form of communication.

1. Endocrine glands: Release hormones DIRECTLY into the circulatory system

2. Hormones

Consists of:

Chemicals released in one part of the body that travel through the bloodstream and affect the

activities of cells in other parts of the body.

growth hormones

Hormone fits receptor on “target” cell

targetcell

non-targetcells

secretingcell

can’treadsignal

can’treadsignal

Pituitary Gland- “the Master Gland”

Hormone: Growth Hormone

1. Stimulates bones to elongate2. Affects metabolism

Pituitary Gland- Growth Hormone

Disorders: Oversecretion: In early childhood = GigantismIn adults = Acromegaly (bones of hands, feet and face enlarge)

Undersecretion:In childhood = Dwarfism Robert

Wadlow

Thyroid Gland

Hormone:

Thyroxine • Regulates metabolism

(necessary for normal physical and mental development)

ThyroxineDisorders: Oversecretion:Nervousness, weightloss

Undersecretion:In childhood, cretinism (mental retardation, small size)

GoiterIodine Deficiency in the diet

= an enlarged thyroid gland

Parathyroid GlandHormone:

ParathormoneControls metabolism of calcium

Necessary for: • Nerve and Muscle function• Blood clotting• Health of Bones and Teeth

Parathyroid Glands

ParathormoneDisorders:

Undersecretion:• Nerve disorders• Brittle bones• Clotting disorders

Adrenal GlandHormones:

CortisoneRegulates carbohydrates, protein and lipid metabolism. (Promotes the change of lipid

and protein to glucose)

Adrenaline1. Raises blood sugar level2. Increases Heartbeat &

Breathing rate

CortisoneDisorders: Oversecretion:Cushing’s Disease – high blood glucose, excess of fat

Undersecretion:Addison’s Disease – low blood glucose,

weight loss

AdrenalineDisorders:

Undersecretion:Inability to deal with stress.

Pancreas: Islets of Langerhans

Hormones:

InsulinStimulates glucose

uptake by cells

GlucagonPromotes liver to change

glycogen to glucose

InsulinDisorders: Oversecretion: Low Blood Sugar

Undersecretion:High Blood Sugar = Diabetes

liver

pancreas

liver

blood sugar level(90mg/100ml)

insulin

body cells takeup glucose from blood

liver storessugar as glycogen

reducesappetite

glucagon

pancreas

liver releasesglucose

triggershunger

high

low

Regulation of Blood Sugar: Negative Feedback

After a meal Between meals

Negative Feedback: Nervous System

high

low

sweating

lowerstemperature

shivering

Body Temperature

raisestemperature

What about the Ovaries and the Testes?

• Don’t worry, we’re saving them for our unit on Reproduction