Endocrine System Chapter 16 Intro Crash Course Video

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

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

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

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

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!

https://www.youtube.com/watch?v=EYX7ACuTBTY Thomas Beatie https://www.youtube.com/watch?v=EYX7ACuTBTY

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 https://www.youtube.com/watch?v=tN78hYn3ehc

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

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

Effects of Hormones on Target Cells Peptide Hormones https://youtu.be/iUworCsaHos Majority of hormones are classified as this Acts as the “boss” directing workers Does not enter the target cell

Effects of Hormones on Target Cells Peptide Hormones https://youtu.be/iUworCsaHos 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

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

Positive Feedback Mechanism The initial stimulus is intensified

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

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

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

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)

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)

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)

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

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

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.

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)

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

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)

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

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

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

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

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.

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”.