the endocrine system

THE ENDOCRINE SYSTEM

Made up of glands release hormones into the bloodstream

Hormones travel throughout the body and relay information

Works with nervous system to control bodyCoordinated by the hypothalamus

receives messages from internal organs Stimulates pituitary gland when a change in

homeostasis occurs

PARTS OF THE ENDOCRINE SYSTEM1. Pituitary gland – “master” endocrine

gland2. Hypothalamus3. Pineal gland

4. Thyroid gland

5. Parathyroid gland

6. Adrenal gland

7. Pancreas

8. Ovaries or Testes

CHECK YOUR UNDERSTANDING… Which part of your brain meshes your

endocrine and nervous systems together?

Without looking at your notes, list as many parts of the endocrine system as you can

PITUITARY GLAND Controls all the other glands Secretes hormones (thyroid-stimulating

hormone, anti-diuretic hormone, growth hormone, and more)

HYPOTHALAMUS Secretes hormones controls pituitary gland

THYROID GLAND Regulates metabolism and growth

Main hormone is thyroxine – contains iodine (think iodized salt)Regulates Energy Use, Food Intake

PINEAL GLAND In brain – “third eye” Sensitive to light Releases melatonin to make you

sleepy

THYROID GLANDHypothyroidism: low thyroxin Lower energy, weight gain

THYROID GLANDGoiter: enlarged thyroid gland (low iodine)

PARATHYROID GLAND

Controls calcium levels in blood and bonesSecretes Parathyroid Hormone (PTH)

ADRENAL GLAND Produces adrenalin (epinephrine) and

noradrenalin (norepinephrine)Fight-or-flight response Increased…

heart rate and blood pressure

respiration ratemuscle efficiencyblood sugar levels

Also releases cortisol which wakes you up

PANCREAS

Controls blood sugar levels - Insulin

Also acts as a gland of the digestive system secreting digestive enzymes

REPRODUCTIVE GLANDS Gonads: ovaries and

testes

Ovaries produce estrogen and progesterone

Sex characteristicsBreastsWidening of hipsSoft skinPubic/underarm hair

REPRODUCTIVE GLANDS

Testes produce androgens, including testosterone

Sex characteristics facial, leg and body hairThicker skinLarge muscle massGrowth of Larynx (deep

voice)

Tammy Thomas – Pro bike racer

CHECK YOUR UNDERSTANDING… Which gland is your “master endocrine

gland”? Which glands sit on top of your kidneys

and make adrenaline? Which gland / hormone makes you get

fatter as you age? What hormones are secreted by YOUR

gonads? Which gland controls your blood sugar

levels, and with what hormone?

NEGATIVE FEEDBACK An increase in something inhibits the

process leading to the increase

Example: your gradesYour grades suckParents get on your caseYou try harder at schoolYour grades go upParents stop harping on youYou stop trying, grades go back down

Video: negative and positive feedback loops (first minute only)

NEGATIVE FEEDBACK LOOPWATER REGULATION You work out and get thirsty Hypothalamus senses you need water Hypothalamus tells pituitary gland to

release anti-diuretic hormone (ADH) Causes body to conserve water No longer thirsty (no more ADH)

What does a diuretic do?

NEGATIVE FEEDBACK LOOP

BLOOD GLUCOSE When you eat, blood

glucose levels go up

Pancreas senses this and releases insulin

Insulin tells cells to take in glucose – so blood glucose levels drop

NEGATIVE FEEDBACK LOOP

BLOOD GLUCOSE When blood glucose drops…

Pancreas senses this and releases glucagon

Glucagon tells liver to release glycogen (glucose)—so blood glucose levels rise

If you’re out of glycogen, hypothalamus stimulates your stomach and makes it growl

CHECK YOUR UNDERSTANDING…In your notebook, work with your partner to create your own example of a negative feedback loop. It does not have to be biological!

ENDOCRINE DISEASE

Two typesType I – juvenile onsetType II – adult-onset

TYPE I DIABETES: “JUVENILE” Pancreas doesn’t make insulin Therefore cells can’t take in glucose Glucose stays in blood—causes high

blood sugar Glucose appears in urine (not normally

there) Treatment

strict diet insulin injections

TYPE II DIABETES: ADULT-ONSET You eat WAY TOO MUCH sugar

Cells get overloaded with sugar

Cells shut down some insulin receptors, or receptors don’t work properly

Therefore cells no longer get enough glucose

Treatment - Diet

Diabetes animation