Endocrine System

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Endocrine System by Mind Map: Endocrine System

1. Testicles

1.1. Spermatogenesis: diploid cell that undergoes mitosis to form new spermatogonia; formation of mature functional spermatozoa

1.2. Male Reproductive Hormones

1.2.1. Androgen: male hormone development of 2ndary sexual characteristics: body hair, voice change, bone/muscle, metabolism Testosterone: made in testicles; reproductive and sexual function; acts on cells to make sperm; affects mood/sex drive Inhibin: correlated with steroli cell function; sperm #, spermatogenesis status and negatively correlated with FSH

1.2.2. Negative Feedback Loop rising testosterone levels acts on hypothalamus and anterior > inhibit release of GnRH, FSH, LH > sertoli cells produce inhibin (released when sperm count is too high) > inhibits release of GnRH + FSH > spermatogenesis slows down

2. Parathyroid Gland

2.1. Metabolic Hormones

2.1.1. Peptide Parathyroid Hormone (PTH) Targets: kidneys, bones, intestine maintains appropriate balance of Ca2+ in the bloodstream in in tissues that depend on Ca2+ for proper functioning PTH works directly on kidney to increase renal calcium reabsorption and decr. renal P3- reabsorption Negative Feedback Loop

3. Thyroid Gland

3.1. Stress Hormones

3.1.1. Amine Triiodothyronine (T3) T3 and T4 hormones work together to regulate body's temp, metabolism, and heart rate; essential for body growth Targets: cells in brain, bone, heart, muscle Thyroxine (T4) Negative Feedback Loop Hypothalamus secretes thyrotropin-releasing hormone (TRH) > TRH stimulates pituitary gland to produce thyroid-stimulating hormones (TSH) > TSH stimulate thyroid gland to secrete hormones > when thyroid hormones are high enough, TRH + TSH stop production (w/o TRH, thyroid gland cannot secret hormones

3.1.2. Parafollicular Cells (C-cells) Peptide Calcitonin

4. Ovary

4.1. Oogenesis: process by which ovaries produce and release eggs/ova

4.2. Corpus Luteum

4.2.1. Female Reproductive System Estrogen: steroid hormone that stimulates the maturation of sex organs during puberty; 2ndary characteristics: breasts/body hair/pelvis widening Target: ovaries, vagina, uterus, breasts, endometrium Positive Feedback Loops Negative Feedback Loops Progesterone: steroid hormone that prepares and maintains the uterus for the implantation of the fertilized egg and the subsequent growth and development of an embryo Target: hypothalamus, pituitary, endometrium, uterus Inhibin: involved in negative feedback control of FSH secretion (luteal phase) Target: hypothalamus Relaxin: inhibits uterus contractions until TOB; relaxes ligaments in pelvis and softens & widens cervix in prep for childbirth Target: uterus

5. Kidney

5.1. Blood Calcium Regulation

5.1.1. Vitamin D Steroid Calcitriol: used to treat hyperparathyroidism (overactive parathyroid glands) and metabolic bone disease in those who have chronic kidney failure; treat/prevents low Ca2+ levels

6. Pituitary Gland

6.1. Secretes major hormones; located in Cranium (below brain); to major lobes: Anterior Lobe & Posterior Lobe

6.2. Neurohormones travel through portal vein that connects capillaries inside hypothalamus to capillaries inside pituitary gland

6.2.1. Hormones released by endocrine cells enter bloodstream to reach target tissue

6.3. Anterior Pituitary

6.3.1. Metabolic Hormones Peptide Growth Hormone (GH)/ Somatotropin

6.3.2. Stress Hormones ACTH long term stressful situations stimulates production of corticosteroids, mineralocorticoids, glucocorticoids

6.3.3. Male Reproductive Hormones LH: stimulates testosterone production from interstitial cells of testes (Leydig cells) Target: steroli cells (testes) FSH: testicular growth; sustain maturing sperm cells Target: leydig cells (testes)

6.3.4. Female Reproductive System Peptide Follicle Stimulating Hormone (FSH): stimulates development of the maturing ovarian follicle and controls ovum production Prolactin (PRL) : milk production; development of mammary glands within breast tissues Luteinizing Hormone (LH): aid in egg maturation and provides the hormonal trigger to cause ovulation and the release of eggs from the ovary Thyroid-stimulating Hormone (TSH): stimulates thyroid to release thyroxine (incr. metabolic rate, regulates growth and development) Adrenocorticotropic Hormone (ACTH): stimulates adrenal cortex to release hormones (glucocorticoids)

6.4. Posterior Pituitary

6.4.1. Stress Hormones Peptide Vasopressin (ADH)

6.4.2. Female Reproductive System Oxytocin: released in large amounts during labour and controls contraction of the uterus during childbirth and lactation; stimulates uterine muscles to contract and increases the production of prostaglandins (further increases contractions) Target: posterior pituitary gland

7. Heart

7.1. Stress Hormones

7.1.1. Atrial Natriuretic Peptide (ANP) synthesized and secreted by cardiac muscle cells in walls of atria when blood Na+ levels and pressure incr. > ANP binds to receptor in kidney and blood vessels > promotes salt excretion > lowers blood volume and relaxes vessel controls electrolyte homeostasis Target: kidneys, cardiovascular system

7.2. Negative Feedback Loops

7.2.1. low cortisol levels > hypothalamus releases corticotrophin-releasing hormone (CRH) (central stress hormone) > pituitary gland releases ACTH into blood > excess amount of hormone in adrenal gland = incr. in cortisol production = incr. cortisol blood levels > cortisol blocks CRH from hypothalamus + adrenocorticotropic hormone from pituitary > ACTH levels decr. = cortisol levels decr.

8. Pancreas

8.1. Blood Glucose Regulation

8.1.1. Peptide Insulin: lowers blood glucose level by instructing target cells to take glucose from blood; secreted by beta cells Targets: liver Glucagon: raises blood glucose levels by stimulating breakdown of glycogen > glucose in liver; secreted by alpha cells; stimulates breakdown of fats > fatty acids + proteins > AA Target: liver stimulates liver gluconeogenesis (AA + non carbs converted to glucose

8.1.2. Negative Feedback Loops alpha + beta cells in pancreas respond to changes by either incr./decr. insulin production and/or glucagon production to achieve homeostasis High blood glucose > stimulates beta cells to incr. production of insulin + alpha cells decr. glucagon production > blood glucose levels decr. Low blood glucose > stimulate beta cells to decr. production of insulin + alpha cells incr. glucagon production > blod glucose levels incr.

9. Hypothalamus

9.1. Maintains homeostasis: controls release of hormones from pituitary gland

9.2. Neurohormones: made by neurons in hypothalamus; diffuse into blood > pituitary gland > controls other endocrine glands with release of other hormones

9.3. Male Reproductive Hormones

9.3.1. GnRH: stimulates production of FSH and LH Target: anterior pituitary

9.3.2. Spermatogenesis

9.4. Female Reproductive System

9.4.1. Gonadotropin Releasing Hormone (GnRH): released every 50-120 minutes; stimulates the pituitary gland to produce FSH and LH and release into the bloodstream Target: pituitary

10. Adrenal Cortex

10.1. Stress Hormones

10.1.1. Steroids Cortisol (glucocorticoids) Target: everywhere; muscle, liver adipose cells released from adrenal cortex through the zona fasciculata layer; hypothalamus-pituitary axis regulates production and secretion incr. blood glucose by promoting breakdowns of fats + proteins; controls sleep/wake cycle and helps energy boosts Aldosterone (mineralocorticoids) produced in cortex of adrenal glands; part of the renin-angiotensin-aldosterone system water balance; water reabsorption Target: Kidneys (absorbs Na+ in blood + release K+ into urine; regulates blood pH)

10.2. Blood Glucose Regulation

10.2.1. Steroid Cortisol: provides body with glucose by tapping into protein stores via gluconeogenesis in liver; can lead to incr. blood sugar levels Targets: liver stimulates liver gluconeogenesis

11. Adrenal Medulla

11.1. Stress Hormones

11.1.1. Amines Norepinephrine Noradrenaline: incr. BP; blood vessels narrow + blood pumped faster Epinephrine/Norepinephrine BOTH: restrict kidney function during stress by constricting blood vessels incr. heart rate + force heart contractions; incr. blood flow to muscles + brain; incr. metabolic rate; control squeezing blood vessels (maintain BP) Short term stressful situations; fight or flight response Target: receptor sites in PM (whole body) Epinephrine Adrenaline: heart rate (faster breathing)

11.2. Blood Glucose Regulation

11.2.1. Adrenaline/Noradrenaline: incr. blood sugar levels by promoting conversion of glycogen > glucose; incr. heart rate and contractility of heart Target: liver