The endocrine system regulates metabolism, growth, development, emotions, and reproduction through hormones released into the bloodstream from endocrine glands. It acts more slowly than the nervous system but has longer-lasting effects. Some key endocrine glands include the hypothalamus, pituitary, thyroid, adrenals, ovaries, and testes. Important hormones include insulin, cortisol, testosterone, estrogen, progesterone, and thyroxine which regulate processes like blood sugar, stress response, and metabolism. The hypothalamus and pituitary gland work together to control hormone release from other glands through negative feedback loops.

1. Science Notes: Ch. 16; The Endocrine System

2. Endocrine Differences from Nervous system
The nervous system works by sending an
action potential along an axon and then a
chemical is released at the end of the nerve
path. Acts quickly, shorter-term effect
The Endocrine system works by an endocrine
gland releasing a hormone directly into the
blood: Acts slower: longer-lasting effect.

3. General Functions
Regulation of metabolism
Regulation of emotions
Regulation of growth & development
Regulation of sexual reproduction

4. Some Specific Functions
Water balance.
Uterine contraction during birth.
Milk release from breasts.
Tissue maturation.
Heart rate.
Blood pressure.
Blood glucose concentration.
Immune cell production.
Reproduction.

5. Glands of the Endocrine System
Hypothalamus
Pituitary
Thymus
Adrenal
Testes & Ovaries
Pancreas
Parathyroid
Thyroid
Pineal body

7. Main Hormones & Their Functions
Copy and memorize 6 of the following hormones
Antidiruretic hormone Regulates fluid & electrolyte balance in the kidney.
Luteinizing hormone Stimulate release of estrogen and testosterone.
Thymosin enhances the ability of the immune system.
Cortisol Immune suppression & stress response.
Testosterone, Estrogen, Progesterone Regulates reproductive processes.
Insulin Regulates blood sugar levels.
Parathyroid hormone Regulates blood levels of calcium in the blood.
Thyroxine Regulation of metabolism.
Melatonin Regulates the onset of puberty by acting on hypothalamus;
regulates our biological clock.
Click here for a detailed list of hormone actions on the Web

8. Definitions
Hormones--turn on, turn off, speed up, slow down
the activities of of different tissues and organs; A
chemical messenger.
The Brain & Nervous System--regulates if a
hormone is released or not, when, & how much.
Target Cell Receptor Proteins--allow hormones to
act on certain organs but not others by the presence
or absence of these cells.

9. Glands to Know...
Hypothalamus:
This gland is the link between the nervous
system and the endocrine system. Found in
the brain.
The hypothalamus receives nerve messages
that produce hormones that control other
adrenal glands.

10. Glands to Know...
Pituitary;
Also found in the brain.
Communicates with hypothalamus to regulate many
body activities.
Releases more types of hormones than any other
gland.
Stimulates production of estrogen, sperm, stimulates
growth, milk production, & maintains skin tone.

11. Negative Feedback
Negative feedback happens when
hormone production reaches a high level
and this triggers the adrenal system to
produce a second hormone which turns off
production of the first hormone.

12. Negative feedback

13. Human Reproductive Biology

14. Human Reproductive Biology

15. Female Menstrual Cycle

16. Early Embryo Development

17. Maintaining the Fetus

18. Two Types of Twins