1. Endocrine System Chapter 16 Intro Crash Course Video

2. What is the Endocrine System?
A system of glands that produce and secrete hormones to regulate & control bodily activities.
Hypothalamus. Parathyroid
Pineal Gland. Pancreas
Pituitary Gland. Thyroid
Thymus. Adrenal
Testes Ovaries

3. Endocrine System: Overview
Works with the nervous system to coordinate activity with body cells
9 major glands

4. Major Endocrine Organs: Which 3 are also part of the Nervous System?
Figure 16.1

5. Hormones – chemical messengers released into bloodstream
Circulating blood delivers hormones to all cells in the body
Although hormones circulate bloodstream, only affects target cells

6. What is the Endocrine System?
Hormones:
regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things
Great informative video!

7.
Thomas Beatie

8. Contain receptors for specific hormones to bind to and react
Target Cells
Contain receptors for specific hormones to bind to and react
Ex: Thyroid stimulating hormone circulates bloodstream, but only binds to thyroid receptors because that is where the receptors are located
Good video

9. Effects of Hormones on Target Cells
Steroid Hormones(Lipid)
Diffuse across cell membrane into target cell
Bind to receptor proteins inside the target cell
Good video

10. Effects of Hormones on Target Cells
Steroid Hormones(Lipid)
5 Classes
Androgens-sexual development
Estrogen-sexual development
Progestins-mediate menstrual cycle and pregnancy
Mineralocorticoids-regulate excretion of salt and water by kidneys
Glucocorticoids-inflammatory reactions and coping with stress

11. Effects of Hormones on Target Cells
Peptide Hormones
Majority of hormones are classified as this
Acts as the “boss” directing workers
Does not enter the target cell

12. Effects of Hormones on Target Cells
Peptide Hormones
Actions of the hormone:
Hormones bind to the receptor on the plasma membrane
Binding leads to activation of an enzyme that changes ATP into cAMP
cAMP activates an enzyme cascade
Many molecules are built or broken down and enter the bloodstream

13. Negative Feedback Mechanism
Reverses original stimulus
Hormone secretion is triggered by an internal or external stimulus.
Hormone levels increase, cells are inhibited
Hormone levels decrease, cells are stimulated

14. Positive Feedback Mechanism
The initial stimulus is intensified

15. 1. Humoral→ response to blood levels of nutrients
Endocrine Glands
Stimulated to make & release their hormones by 3 major types of stimulus
1. Humoral→ response to blood levels of nutrients
Ex: Na+ decreases, aldosterone secreted
2. Neural→ nerves stimulate release
Ex. Epinephrine released from Sympathetic NS
3. Hormonal→ response to other hormones
Ex. Pituitary gland release hormones to trigger release of testosterone

16. Excessive release of hormone Hyposecretion
Disorders
Hypersecretion
Excessive release of hormone
Hyposecretion
Inadequate release of hormone
Good video

17. 1. Hypothalamus Major link between nervous & endocrine systems
Controls the pituitary gland & the release of its hormones
Corticotropin-releasing hormone (CRH)
Thyrotropin-releasing hormone (TRH)
Growth hormone-releasing hormone (GHRH)
Gonadotropin-releasing hormone (GnRH)
Antidiuretic hormone (ADH) and Oxytocin-
produced here, but released by pituitary gland

18. 2. Pituitary Gland
secretes 9 different hormones (AP-anterior pituitary)
controlled by the hypothalamus (PP-posterior pituitary)
Some hormones that are released are:
Thyroid-stimulating hormone (TSH): controls secretion of thyroid hormones by thyroid (AP)
Adrenocorticotropic hormone (ACTH): stimulates adrenals to secrete cortisol as a result of stress (AP)
Follicle-stimulating hormone (FSH): Females→ development of oocytes & secretion of estrogen; menstrual cycle / Makes→ production of sperm (AP)

19. Prolactin: stimulates production of milk in females only (AP)
2. Pituitary Gland
secretes 9 different hormones (AP-anterior pituitary)
controlled by the hypothalamus (PP-posterior pituitary)
Luteinizing hormone (LH): Females→ secretion of estrogen & progesterone, stimulates ovulation/ Males→ stimulates testosterone (AP)
Human Growth Hormone (HGH): stimulates bone and muscle growths; lipidosis (AP)
Prolactin: stimulates production of milk in females only (AP)

20. Oxytocin: stimulates uterine contraction; orgasm to move sperm (PP)
2. Pituitary Gland
secretes 9 different hormones (AP-anterior pituitary)
controlled by the hypothalamus (PP-posterior pituitary)
Melanocyte stimulating hormone: stimulates melanocytes to secrete melanin to darken skin and/or hair (AP)
Oxytocin: stimulates uterine contraction; orgasm to move sperm (PP)
Anti-diuretic hormone: stops urine production (PP)

22. 3. Thyroid Gland Controlled by pituitary gland & hypothalamus
Releases of 2 hormones: T3 (triiodothyronine) & T4 (thyroxine)
Responsible for metabolism
Iodine is necessary to produce T3 & T4 hormones

23. 4. Parathyroid Glands Located on thyroid gland
Controls calcium levels in the bloodstream

24. Effects of Parathyroid Hormone
When Ca2+ levels are high in bloodstream:
The thyroid gland secretes calcitonin into the blood, which stimulates the osteoblast to take Ca2+ in from the bloodstream and store it in the bones. This lowers the levels of Ca2+ in the bloodstream
When Ca2+ levels are low in the bloodstream:
The parathyroid gland secretes parathyroid hormones into the bloodstream, which stimulates the osteoclasts to break down bone releasing stored Ca2+ into the blood which increases Ca2+ levels.

25. 5. Adrenal Glands Located on top of kidneys
Production of hormones that impact our development and growth, our ability to deal with stress, and help to regulate kidney function.
Aldosterone: increases sodium & water levels, while decreasing potassium blood levels (cortex)
Cortisol: increase protein breakdown, released in response to stress (cortex)
Androgens: growth of pubic and axillary hair (cortex)
Epinephrine & norepinephrine: adrenaline for SNS during stress or danger (medulla)

26. Adrenal Glands When levels of Na+ are low in the bloodstream (low BP):
Kidneys secrete renin into the bloodstream which then stimulates angiotensin 1 & 2, which stimulates the adrenal cortex to secrete aldosterone. This causes the kidneys to reabsorb Na+ and water from kidneys returning it to the bloodstream (will increase blood pressure)
When level of Na+ are high in the bloodstream (high BP):
It causes blood pressure to rise which triggers the heart to release atrial natriuretic hormone (ANH). This hormone inhibits the secretion of aldosterone from the adrenal cortex. The kidneys will excrete Na+ and water through urine and blood pressure will decrease making Na+ levels and blood pressure return to normal.
Adrenal Glands

27. Part of endocrine & digestive system
6. Pancreas
Part of endocrine & digestive system
Responsible for glucose levels in blood
Glucagon: raises glucose levels in the blood (alpha cells)
Insulin: lowers glucose levels in the blood (beta cells)

28. 7. Ovaries Female reproductive organs Secrete the following hormones:
Estrogen & progesterone: works with pituitary gland to regulate female cycle & secondary sex characteristics
Relaxin: helps dilate cervix during birth
Inhibin: stops production of oocytes

30. 8. Testes Male reproductive organ Secrete the following hormones:
Testosterone: stimulates production of sperm & secondary sex characteristics
Inhibin: Stops the production of sperm

32. 9. Pineal Gland Located inside the brain
Responsible for sleep/wake cycles
Secretes:
Melatonin: always is secreted, but more when dark and less when light

33. 10. Thymus Plays a role in secreting hormones associated with immunity
Production of T-cells (lymphocytes) in the Immune System
Larger in children & decreases in size with age
Secretes Thymosin-stimulates development of T-cells

34. Other: Leptin
a peptide hormone produced by adipose tissue that acts on the hypothalamus and plays a crucial role in appetite and weight control.
It is thought to have 2 major functions:
1. It crosses the blood-brain barrier and binds to receptors in the appetite center in the brain, regulating brain cells that tell you how much to eat.
2. it increases sympathetic nervous system activity, which stimulates fatty tissue to burn energy.

35. Other: Prolactin (Childbirth- females only)
released into the bloodstream during pregnancy from the pituitary gland and stimulates production of milk. Once baby is delivered, the oxytocin (as mentioned already) allows the milk to be released. Continued production of milk depends on the suckling of the nipple by the baby
Oxytocin (Childbirth- females only)
stimulates the uterus to contract and acts on the breast to produce milk ejection or “milk let-down”.