1. Endocrine System

3. Chemical Messengers called Hormones.
Chemical Regulation Is
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 (release) hormones via the Endocrine System.

4. Hormones Are …
Chemicals secreted in one area of an organism, which affect responses in other areas.
Dependent 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

5. The Human Endocrine System – Important Vocabulary
Hormones: Chemical messengers that are transported throughout the body via the blood stream (in plasma).
Gland: Responsible for
synthesizing and secreting
hormones into the bloodstream
Target Organ: Organ that
is affected by hormones

6. 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

7. The Human Endocrine System – Target Cells
** A cell can be a target cell for more than one hormone.
** A cell can have more than one receptor.

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

9. Hypothalamus & Pituitary Gland

10. Hypothalamus & Pituitary Gland
Both are located in the brain, and act as a link between the Nervous and Endocrine Systems
Hypothalamus
Pituitary
Produces Stimulating Hormones which function to stimulate the pituitary gland
(The Hypothalamus acts as the link between the nervous and the endocrine system)
(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.

12. Pituitary Gland Hormones & Targets

13. Thyroid & Parathyroid Thyroxin production requires iodine .
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 parathyroid 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.

14. Adrenal Glands located on top of the kidneys. Two regions
a. Adrenal cortex
b. Adrenal medulla

15. Adrenal Glands Adrenal cortex (outer portion) It secretes two hormones
Cortisol: 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.

16. Adrenal Glands 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.

17. Pancreas
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.
Alpha Cells – Produce Insulin
Beta Cells – Produce Glucagon

18. Ovaries 7. Ovaries Found only in the female reproductive tract.
These glands several hormones:
Estrogen : influences the development of female secondary sex characteristics.
Progesterone which prepares the uterus for a pregnancy.

19. Testes 8. The Testes Found only in the male reproductive tract.
Testosterone: influences the development of male secondary sex characteristics.

20. Thymus Gland 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. 20

21. Thymus Gland – Child vs. Adult

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

23. Negative Feedback Loop for Blood Sugar (Glucose) Levels
1. A sensor detects high blood sugar levels
2. The pancreas releases insulin
Negative Feedback Loop for Blood Sugar (Glucose) Levels
4. Lower blood sugar leads to shutting off insulin
3. Blood Sugar Level Drops 23

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

25. Malfunctions of the Endocrine System
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.

26. Comparisons of the Nervous & Endocrine Systems
Similarities
Differences
Both secrete chemicals
Nervous System: Neurotransmitter
Endocrine System: Hormones
** These are MESSENGERS**
Both play a role in homeostasis
Nerve responses are faster
Endocrine responses are of longer duration than nerve responses

27. Chemical Control in Plants
A. Hormones coordinate growth, tropisms (response to a stimulus) 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

28. Plant Tropisms
E. Unequal distribution of auxins causes unequal growth responses called tropisims
Tropism = 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.

29. Phototropism

30. Geotropism

31. Endocrine System HYPOTHALAMUS PITUITARY GLAND PARATHYROID THYROID
ADRENAL GLANDS
PANCREAS (Islets of Langerhans)
gonads
OVARIES
TESTES
OVARIES