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What is Endocrinology?
Study of hormones & endocrine glands.
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What are the pure Endocrine Organs? (5)
*Endocrine cells of epithelial origin.
- 1) Pituitary
- 2) Pineal
- 3) Thyroid
- 4) Parathyroid
- 5) Adrenal Glands
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What are the organs containing Endocrine cells? (4)
- 1) Pancreas
- 2) Thymus
- 3) Gonads
- 4) Hypothalamus (neuroendocrine organ)
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Location of the major endocrine glands - see slide.
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The Endocrine System - an overview.
~is a system of what type of glands?
Interacts closely w/ what system for physiological functions?
System of "ductless" glands.
Interacts closely w/ Nervous System.
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What is the difference between Exocrine vs Endocrine?
Exocrine: chemicals pass through duct --> lumen.
Endocrine: hormones travel through circulatory system to other cells.
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Hormone production & Exocytosis.
Synthesis
Packaging
Storage
Secretion
- Synthesis
- Preprohormone --> Prohormone
- Packaging
- Prohormone --> hormone
- Secretion
- Hormone (end of any "pro" fragments)
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Chemical categories of hormones.
Give examples:
AA derivatives
Peptide / protein hormones
Steroid hormones
AA derivatives: thyroid hormones & catacholimines.
Peptide/protein hormones: tropic hormones & releasing factors.
Steroid hormones: cholesterol derivatives like estradiol/testosterone.
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Mechanism of hormone action.
Explain the pathways of each: (4 each)
Peptide hormones (water-soluble; cell surface receptors)
Steroid hormones (lipid-soluble; intracellular receptors)
- Peptide:
- 1) water-soluble hormone secreted
- 2) hormone binds to receptor on surface of target cell
- 3) cascade of biochemical reactions ends by activating an enzyme
- 4) altered cell activity.
- Steroid:
- 1) lipid-soluble hormone secreted
- 2) hormone passes through cell membrane & binds to receptor in interior of target cell.
- 3) genes activated leading to production of new proteins.
- 4) altered cell activity.
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Control of hormone secretion.
Secretion is triggered by 3 major types of stimuli, what are they?
Humoral
Neural
Hormonal
Hormonal: release of hormone into the blood stream
Neural: nerve fibers stimulate cells in gland.
Hormonal: hormone released from a gland triggers release of a hormone from a target gland.
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Endocrine control mechanisms.
Controlled by?
Humoral
Neural
Hormonal
- Humoral: (control from blood)
- -parathyroid gland monitors Ca+2
- Neural (control from symp. NS)
- -adrenal medulla (norepinephrine/epinephrine)
- Hormonal (control from pituitary gland)
- -stimuli received from other glands.
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Thyroid gland.(aka "shield-like" cartilage)
Histology of thyroid gland.
-follicular cells are..
-thyroid follicle
-colloid, a fluid follicle storing what?
follicular cells: simple cuboidal epithelial cells.
thyroid follicle: circle of follicular cells
colloid: protein-rich fluid in follicle stores THYROID HORMONE.
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Anatomy of thyroid gland - see slide.
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Production & secretion of TH.
(5)
- 1) Follicular cells synthesize Thyroglobulin.
- -transported into colloid (storage)
- 2) Follicular cells transport iodine into colloid
- -3 or 4 molecules of iodine bind thyroglobulin.
3) The hormone is stored in colloid as pre-t3 or pre-t4.
4) Thyroid stimulating hormone - causes endocytosis of pre t3 or pre t4 back into follicular cell.
5) TH exocytosis into blood vessel as t3 or t4.
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Too much TH equates to..
Insufficient TH equates to..
- Hyperthyroidism:
- -bulging and protruding eyeballs, weight loss, hyperthermia.
- Hypothyroidism:
- Due to lack of iodine to synthesize the molecule. Goiter is an enlarged thryoid gland.
- -low metabolic rate, hypothermia, impaired development.
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What cells secrete Calcitonin hormone?
What organ stimulate Ca+2?
Why is it secreted?
Under what control?
Parathyroid cells secrete Calcitonin.
Stimulant: Kidneys
Secretion: in response to elevated Ca+2 in blood, therefore, LOWERING Ca+2 in blood.
Under Humoral control.
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Parathyroid gland.
Anatomy - see slide.
Histology - see slide
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Parathyroid hormone.
Under what control?
Synthesized/secreted by which cells?
Under Humoral control.
- Synthesized/secreted by Chief cells in response to low Ca+2.
- -INCREASES Ca+2
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Adrenal glands.
Anatomy - see slide
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Adrenal Cortex vs Medulla.
Cortex (3 layers)
-glomerulus
-fascioculata
-reticularis
Medulla
- Cortex:
- glomerulus: aldosterone
- fasciculata: cortisol & androgens
- Medulla:
- -epinephrine
- -norepinephrine
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Autonomic control of Adrenal Medulla.
Chromafin cells, are under what control?
Neural control.
Produce epinephrine/norepinephrine in response to fight/flight.
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Histology of Adrenal Cortex - see slide.
Contains:
Adrenal Medulla
Adrenal Cortex
-The cortex is divided into 3 subgroups:
1) Zona Reticulus (innermost/smallest)
2) Zona Fascialata (middle/largest)
3) Zona Glomerulus (outermost cortex)
Which does each secrete?
1) Reticulus (rete = network): secretes androgens in response to aCTH stimulation.
2) Fascialata ("fasicle of sticks"): Corticosteroids, glucocorticoids (cortisol)
3) Glomerulus ("balls of yarn"): aldosterone
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Stress.
A) Glucocorticoids (adrenal cortex)
B) Catecholomine hormone (adrenal medulla)
-List what each effects.
-Which is for short term stress, long term stress response?
-Which is innervated by the Symp NS, by ACTH?
- Glucocorticoids (long term; adrenal cortex; ACTH)
- -effects lipid & carb. metabolism, immune system, & damage repair.
- Catecholomine horomone (adrenal medulla; Symp. NS)
- -effects lipid & carb. metabolism, cardiovascular system, CNS.
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Name 3 things the Kidneys secrete.
(hint: REC)
Define each of the 3 secretions.
- 1) Renin: angiotensinogen --> angiotensin I --> angiotensin II (in lungs) --> stimulates aldosterone production by adrenals.
- 2) Erythropoietin: RBC production.
- 3) Calcitriol: synthesized by Vit D, secreted in response to LOW PTH, increases absorption of Ca++ by enterocytes in gut.
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Endocrine functions of the Pancreas.
Anatomy (see slide): where is it located?
-(hint: behind which organ tucked into what letter shaped pocket of duodenum).
Located in "retroperitoneum" behind stomach tucked into the J-shape pocket of duodenum.
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The Pancreas (card 2)
What are the Exocrine secretions carried by pancreatic duct to duodenum to aid in digestion? (2)
(hint: helps break down and neutralizes acid in stomach)
- 1) digestive enzymes (pancreatic enzymes)
- 2) HCO3- (bicarbonate; acid neutralization in stomach)
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The Pancreas (card 3); (see slide for cell illustrations)
*Pancreatic hormones act under Humoral control of glucose concentrations in the blood.
Endocrine functions of the Pancreas.
-Pancreatic islets (of Langerhans) contain alpha, beta, & delta cells. (endocrine islets = AgBi/D cells)
-Give each of their functions.
1) Alpha: glucagon --> glycogen breakdown (liver releases glucose), increased blood glucose levels (BGL).
2) Beta: insulin --> glucose uptake, decreasing blood glucose levels (BGL).
- 3) Delta: produce Somatostatin (GH inhibiting hormone)
- -Inhibits secretion of glucagon & insulin
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Heart.
What is the Atrial Natriuretic Peptide (ANP); name what they stimulate & inhibit).
ANP: stimulates H2O & Na+ loss to LOWER BP; inhibits ADH and Aldosterone release.
*Acts under Humoral control from monitoring BP.
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The Pineal Gland (epithalamus)
Pineal gland is a small gland on the roof of what cephalon?
What types of cells does it secrete and what do these cells affect?
(hint: affects body rhythm..)
Small glandon the roof of the "diencephalon".
- Contains "pinealocytes" that secrete Melatonin.
- -acts under humoral control of LIGHT-SENSITIVITY.
Melatonin: affects circadian rhythms & slow reproductive function.
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The Thymus.
Where is it located? (hint: top of rib cage in chest)
What substances does it produce? (2; hint: both start w/ thy)
What happens as you age?
Located behind Sternum in Thorax (see slide).
- Produces:
- 1) Thymosin: important for lymphocyte maturation & development.
- 2) Thymopoeitin
*Diminishes & regresses w/ age.
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Reproductive System (Gonads)
Name the pathway of production for the OVARY/TESTES.
FSH --> Ovary --> estradiol
LH --> Testosterone
*Both under hormonal control of Hypothalamus & anterior pit.
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Attach the analogy for the Hypothalamus, Anterior Pituitary, Peripheral gland/organ.
(Vice President, Workers, President)
- Anterior Pituitary
- (Vice President)
- Peripheral gland/organ
- (Workers)
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The Hypothalamus "master controller of the Endocrine System"
Name 3 functions of the Hypothalamus.
1) Controls hormonal release from Adrenal Gland (via Sympathetic NS).
2) Produce 2 hormones that are released in the Posterior Pituitary (oxytocin ADH aka vasopressin)
3) Release Regulatory Hormones to control Anterior Pituitary.
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Anatomy of Hypothalamus & Pituitary.
What does the "Adenohypophysis" contain? (3) (Anterior P.)
-hint: pars..
What does the "Neurohypophysis" contain? (3) (Posterior P.)
What 2 parts are the infundibulum consist of?
- Andenopophysis: ("gland undergrowth") = anterior pit.
- 1) pars tuberalis
- 2) pars intermedia (secretes MSH)
- 3) pars distalis (secretes other anterior pit. hormones)
- Neurohypophysis: ("nervous undergrowth") = posterior pit.
- 1) median eminence
- 2) infundibular stalk
- 3) pars nervosa (releases oxytocin & ADH)
Infundibulum: "funnel"; pars tuberalis + infundibular stalk.
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Formation of the Anterior/Posterior (adrenohypophysis/neurohypophysis).
-What forms during week 3?
-Late second month, what loses contact?
-What happens during the fetal period?
Week 3: Neurohypophyseal/hypophyseal pouch form.
2nd month: Hypophyseal pouch loses contact w/ roof of pharynx.
Fetal period: Both pituitary glands have formed.
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The Pituitary (Adenohypophysis; anterior pituitary)
What 3 parts is it made up of?
-hint: pars..
Hormone secretion by the adenohypophysis is controlled by secretion of releasing factors produced by the ___ and delivered to the pituitary via the _____ ("" portal venous system)
- 1) pars distalis (major part)
- 2) pars intermedia (minor part) btwn DISTALIS & NERVOSA and the..
- 3) pars tuberalis (minor part) around the infundibulum.
Produced by the Median Eminence of Hypothalamus.
Delivered to the pituitary via the hypophyseal portal venous system.
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