1. Endocrine System Notes (35.3)
I. Endocrine system involved in control of body (overview)
II. Endocrine glands release hormones into blood
A. The hypothalamus is the part of the brain that controls the pituitary
B. The pituitary gland controls most endocrine glands (master endocrine gland)
C. Hormones are chemical messengers
D. Hormones affect target tissue cells.

2. III. Negative feedback control—
A. Negative feedback system—a self-regulating system in which a hormone, or its effects are fed back to inhibit the original signal.
Examples:
1. hGH (human growth hormone)—
a. hGH causes growth by raising blood sugar.
b. When blood sugar is high enough for sufficient growth,
hGH secretion stops.

3. 2. ADH (antidiuretic hormone)
a. Dehydration stimulates secretion of ADH by pituitary
b. ADH helps you retain water (by concentrating urine)
c. If the hypothalamus senses enough water is in the blood, ADH production is stopped.

4. 3. insulin and glucagon (secreted by pancreas)
a. insulin lowers blood sugar (by causing cells to take in glucose).
b. Once blood sugar is low enough, insulin secretion stops.
c. glucagon raises blood sugar (by causing the liver to release glucose).
d. Once blood sugar is high enough, glucagon secretion stops.

5. Summary of glands (study p. 930—figure 35.10)
Hypothalamus
Pituitary
Thyroid
Parathyroid
Adrenal glands
Pancreas (Islets of Langerhans)
Ovaries
Testes

6. Optional Material Follows

7. 2. diffuse freely into cells through plasma membrane.
II. Hormone Action
A. Steroid hormones
1. made from lipids
2. diffuse freely into cells through plasma membrane.
3. bind to receptor inside cell
4. hormone-receptor complex activates synthesis of mRNA molecules at nucleus
5. mRNA is used to make the right proteins
B. Amino acid hormones
1. bind to receptors on plasma membrane
2. this opens ion channels or causes other signals that activate enzymes in cell.
3. enzymes cause various activities in cell.
Animations

8. III. Adrenal hormones and stress.
A. Adrenal glands on top of kidneys
1. medulla (inner portion)
a. secretes 2 amino acid hormones—epinephrine and norepinephrine
i. involved in fight or flight (increase heart rate, blood pressure, respiration, muscle contraction efficiency, blood sugar)
2. Cortex (outer portion)
a. secretes steroid hormones like glucocorticoids and aldosterone that increase blood glucose and blood pressure.
Adrenal animation
NOW take out a separate piece of paper. We will be having a POP QUIZ (30 points)!

9. IV. Thyroid and Parathyroid Hormones A. Thyroid gland.
1. in neck (swelling causes goiters)
2. regulates growth, metabolism and development
3. hormones
a. Thyroxin—major metabolic growth hormone b. Calcitonin—regulates calcium levels (increases calcium absorption by bone/ decreases amt. in blood)
The Operation Good Samaritan team helped many people with goiters by performing thyroidectomies (removal of the thyroid gland tissue), which is usually curative with life changing results.
Note: After the removal of a thyroid patients usually take prescribed oral synthetic thyroid hormones to prevent the most serious manifestations of the resultant hypothyroidism. (Wikipedia)

10. B. Parathyroid glands (also in neck) 1. hormones
a. parathyroid hormone (PTH)—increases calcium levels in blood.
VI. Summary of glands (study p. 960—figure 35.11)
Hypothalamus
Pituitary
Thyroid
Parathyroid
Adrenal glands
Pancreas (Islets of Langerhans)
Ovaries
Testes