1. Endocrine System
Endocrine System maintains: Homeostasis, controls growth, development, reproduction, and metabolism by releasing different hormones.

3. What are hormones?
Hormones-chemical messengers secreted by cells to regulate the activity of other cells
Target organs contain receptor sites specific to a hormone

4. Steroid Hormone Actions:
1) diffuse through plasma membrane of target cell 2) enter the nucleus 3) bind to a specific receptor protein to form a complex 4) binds to DNA 5) activates certain genes which are translated to result in synthesis of new proteins

5. Non Steroid Hormone Action:
does not enter target cells
instead binds onto the target cell plasma membrane that results in a response by the cell to the hormone.

6. Negative Feedback Loops
The net effects of the response to the stimulus is to shut off or reduce the original stimulus.
Examples: blood glucose levels, acute stress levels

7. Positive Feedback Loops
Response enhances the original stimulus so that the response is accelerated.
Example: childbirth. The force of the baby’s head on the cervix causes the uterus to contract more and more

8. Endocrine gland stimuli types:
Hormonal- endocrine glands release hormones because of the influence of other hormones
Humoral- glands release hormones because of changing ions or minerals
Neural- hormone release in response to nervous system stimulation (sympathetic)

10. Major Endocrine Organs:
Pituitary- grape size, hangs from hypothalamus, surrounded by bone (sella turcica)
Two parts:
Anterior
Posterior

11. Anterior Pituitary secretes:
Growth hormone(GH)- effects growth of skeletal muscle and long bone
Prolactin- targets breast to produce milk after childbirth
Adrenocorticotropic(ACTH)- regulates the hormones in the adrenal cortex
Thyroid Stimulations Hormone(TSH)- influences growth and activity of the thyroid
Gonadotropic: regulates hormone activity of the gonads
FSH- function- follicle stimulating hormone- egg and sperm production
LH- triggers ovulation of an egg

12. Posterior Pituitary secretes:
Oxytocin- released during childbirth to stimulate contractions of the uterine muscle
Antidiuretic (ADH)- inhibits urine production by causing the kidneys to absorb water

13. Thyroid

14. Thyroid- located on the trachea (windpipe)
Thyroid hormone (T4, T3)- controls the rate that glucose is burned or oxidized
Calcitonin- decreases blood calcium levels by causing calcium to be deposited in bone

15. Parathyroid- tiny masses of tissue on the thyroid
Parathyroid hormone (PTH)- regulator of calcium in the blood-breaks down bone to release Ca

19. Adrenal- on top of the kidney:
Aldosterone- important in regulating concentrations of sodium and potassium-reabsorbs water, increases blood pressure
Cortisol- helps the body to resist stress Androgens and Estrogens- are collectively called sex hormones (gonadocorticoids)

20. Medulla:
Catecholamines- 2 examples are epinephrine (adrenaline) and norepinephrine

22. Pancreas- Behind the stomach in abdomen
Insulin- acts on all body cells to increase the ability to transport glucose across plasma membranes-reduces blood glucose levels
Glucagon- acts as an antagonist to insulin-raises blood glucose levels by breaking down glycogen in liver

23. Gonads
Females: ovaries
Males: Testes

24. Homeostatic Imbalances
Goiter- enlargement of the thyroid gland that results when the diet is deficient in iodine
Diabetes mellitus- glucose level rise in the absence of insulin
Acromegaly- hypersecretion of GH (growth hormone) after long bones have finished growing. Leads to elongation of jaw, eyebrows, feet, and hands

25. Acromegaly

26. Gigantism

27. Goiter