1. Chemical Regulation Is Chemical Messengers called Hormones.
…the Control and Coordination of the various life activities within an organism using
Chemical Messengers called Hormones.
I. Chemical control in Animals
Special endocrine glands synthesize and secrete hormones via the Endocrine System.

2. Hormones Are …
chemicals secreted in one area of an organism, which affect responses in other areas.
. . . dependant on the Circulatory System
because it aids in the distribution of hormones
through out an organism.
Hormones control metabolic activities such as reproduction and metamorphosis
Metamorphosis = changes in form, that some organisms go through from egg to adult
ex. Caterpillar to butterfly, Maggot to fly, Tadpole to frog

3. The Human Endocrine System
Important Vocabulary
Hormones: Chemical messengers that are transported throughout the body via the blood stream.
Gland: Responsible for
secreting hormones into
the bloodstream
Target Organ: Organ that
is affected by hormones

4. The Human Endocrine System
How does it work?
1. A Gland releases hormones in to the blood stream when it is stimulated to do so.
2. The hormones travels
through the blood stream
until it reaches the target
organ.
3. The target organ receives
the hormone in a special
receptor that is specific.
4. Once the hormone binds, the target organ responds

5. The Human Endocrine System
1. Hypothalamus
2. Pituitary Gland
4. Parathyroid
3. Thyroid
5. Thymus
6. Adrenal Glands
7. Pancreas
8. Ovaries
8. Testes

6. Hypothalamus - produces Stimulating Hormones which function to stimulate the pituitary gland
(the Hypothalamus acts as the link between the nervous and the endocrine system)
2. Pituitary gland – (the master gland) located at the base of the brain. Secretes numerous Stimulating hormones including:
a. Growth Stimulating Hormone (GSH) stimulates the growth of long bones.

8. Parathyroid – Four tiny
3. Thyroid - located in the neck. Produces thyroxin, which regulates the rate of cellular metabolism
Thyroxin production requires iodine .
Parathyroid – Four tiny
patches of tissue embedded in the thyroid gland.
It secretes parathyorid hormone, which controls the metabolism of calcium and blood calcium levels. which is necessary for proper nerve function, blood clotting and proper growth of bones and teeth.

9. Adrenal glands - located on top of the kidneys.
Two regions
a. Adrenal cortex
b. Adrenal medulla.
a. Adrenal cortex (outer portion) secretes two hormones.
A hormone promotes the conversion of body fat and protein into glucose.
ADH: A hormone promotes that re-absorption of sodium and chloride ions into the blood stream by the kidneys.

10. Adrenal medulla (inner portion)
The adrenal medulla secretes the hormone adrenaline (epinephrine) in times of emergency. This hormone is responsible for “Fight or Flight”
Adrenaline increase blood sugar levels, and accelerates the heart and breathing rates.

11. Islets of Langerhans of the Pancreas – small groups of cells in the pancreas responsible for maintaining blood sugar levels. They secrete the hormones insulin and glucagon.
Insulin helps convert glucose to glycogen to be stored in the cells of the liver and muscles.
Glucagon changes the glycogen back to glucose, when needed.

12. 7. Ovaries
Found only in the female reproductive tract.
These glands secrete several hormones:
Estrogen, which influences the development of female secondary sex characteristics.
Progesterone which prepares the uterus for a pregnancy.
8. The Testes
Found only in the male reproductive tract.
Testosterone: influences the development of male secondary sex characteristics.

13. Thymus: The Thymus produces the hormone Thymosin.
Thymosin is responsible for the development of T-Cells. T-Cells are essential for the immune system to work properly.
The Thymus is present at birth, develops during childhood and then gradually disappears during adulthood. 13

14. ** Negative Feedback - a communication system where the production of a chemical (usually a hormone) effects another by returning a condition to its normal values.
Ex. Home heating system
TSH and Thyroxin levels
Blood sugar levels and insulin production

15. Negative Feedback Loop For Blood Sugar
1. A sensor detects high blood sugar levels
2. The pancreas releases insulin
Negative
Feedback
Loop
For
Blood Sugar
4. Lowered blood sugar leads to shutting off insulin
3. Blood Sugar Level Drops 15 15

16. III. Malfunctions of the Endocrine System
1. Goiter - enlargement of the thyroid gland, associated with an iodine deficiency in the diet.

17. Diabetes – inability to store excess glucose as glycogen
Type I diabetes - insulin deficiency results in an high blood sugar level.
Type II diabetes – lack of insulin receptors on the cells of the liver, causes an inability to store glucose. Obesity and an inactive lifestyle, are known causes.

18. Comparison of Nervous and Endocrine systems
1. Similarities
A. both secrete chemicals
(neurotransmitters and hormones)
B. both play a role in homeostasis
2. Differences
A. Nerve responses are faster
B. Endocrine responses are of longer duration than nerve responses

19. Chemical Control in Plants
A. Hormones coordinate growth, tropisims, and reproduction.
B. Plants have no special organs for hormone production
Hormone production is mostly in the actively growing areas such as the tips of roots and stems, buds and seeds.
D. Auxins - are one type of plant hormone that controls the rate of growth

20. E. Unequal distribution of auxins causes unequal growth responses called tropisims
Tropisim = unequal growth.
Unequal auxin distribution can be caused by stimuli such as light or gravity Ex. Phototropism - bending of stem towards light
Ex: Gravity – Geotropism
Tropisms are usually advantageous and help a plant to survive.

21. Endocrine System HYPOTHALAMUS PITUITARY GLAND PARATHYROID THYROID
ADRENAL GLANDS
PANCREAS (Islets of Langerhan
gonads
OVARIES
TESTES
OVARIES

23. Steroid Hormone Action

24. Protein Hormone

25. Maintaining normal glucose levels

27. Labeled Endocrine System

28. Negative Feedback B C D A E self regulation
one hormone inhibits production of the other B C D A E