Endocrine System

Question 0

Hormone Generic Timescale, Mechanism, Regulation

Answer 0

Timescale|| compared to neurotransmitter, slower, indirect, more long-lasting (time of effect: hours, days)

Mechanism|| released into general circulation and bind to specific receptors, found extra or intracellularly

Regulation|| if too much – downregulation of receptors ; if too little – upregulation of receptors

Question 1

Endocrine v. Exocrine glands

Answer 1

Endocrine: release hormones into body fluids
Exocrine: release enzymes to external environment through ducts (ex. Sebaceous, sudoriferous, mucous glands)

Question 2

Basic Hormone Types

Answer 2

1. Peptide hormones
2. Steroid hormones
3. Tyrosine derivatives

Question 3

Peptide Hormones (production)

Answer 3

Rough ER || preprohormone manufactured
ER lumen || cleavage of pre- portion into prohormone, sent to Golgi
Golgi || cleavage of pro portion of prohormone and addition of carbohydrate tail (some hormones), packaging into secretory vesicles
Secretory vesicles || release contents via exocytosis once they receive signal to do so

Question 4

Peptide Hormones (characteristics)

Answer 4

1. Water soluble, therefore hard time diffusing through effector cell membrane
2. Bind to extracellular receptors that may act in various ways:
   || ligand gated ion channel or activate nearby channels
   || second messenger activates intracellularly cascade (via cAMP, cGMP, calmodulin) — this mechanism allows a small hormone concentration to have amplified effects

Question 5

Effector

Answer 5

Target cell

Question 6

Steroid Hormones (production and characteristics)

Answer 6

Production || synthesized in smooth ER and mitochondria, derived from (and similar to) cholesterol

Characteristics || lipid soluble | transport through blood requires being bound to protein | can diffuse through effector membrane, bind to cytosolic protein, and can go into nucleus to affect TRANSCRIPTION

Typical effect || increase specific cellular protein expression

Question 7

Tyrosine Derivative Hormones

Answer 7

Thyroid Hormones || lipid soluble, transported through blood by plasma protein carriers to which they have high affinity (therefore slow release into effector tissue), affect transcription in large amount of tissue

Catecholamines (Epinephrine, Norepinephrine) || peptides, water soluble! bind to extracellular receptor and activate second messenger (usually cAMP)

Question 8

Anterior Pituitary (location, regulation)

Answer 8

|| aka adenohypophysis
|| located beneath the hypothalamus
|| release or inhibition of hormone release controlled by hypothalamus, which is controlled by nervous system

Question 9

Anterior Pituitary Hormones

Answer 9

1. Human growth hormone (hGH)
2. Adrenocorticotropin (ACTH)
3. Thyroid stimulating hormone (TSH)
4. Follicle stimulating hormone (FSH)
5. Prolactin
6. Leutenizing hormone (LH)

Question 10

hGH (human growth hormone)

Answer 10

|| peptide, released by Anterior Pituitary
|| stimulates growth in nearly all tissue types by
Increasing rate of protein synthesis
Increasing cell size
Increasing frequency of mitosis
Increasing use of fatty acids for energy | decreasing use of glucose for energy
Increasing transport of amino acids across cell membrane
Increasing translation and transcription

Question 11

TSH (thyroid stimulating hormone)

Answer 11

|| peptide hormone, released by Anterior Pituitary
|| stimulates thyroid:
       Cell size
       Rate of T3 and T4 secretion
       Cell number

Question 12

ACTH (adrenocorticotropic hormone)

Answer 12

|| peptide, released by Anterior Pituitary
|| stimulates Adrenal Cortex release of glucocorticoids (stress response)
|| second messenger, via cAMP

Question 13

Prolactin

Answer 13

|| peptide hormone, released by Anterior Pituitary
|| promotes lactation (milk production)
|| its release is Tonically inhibited by hypothalamus while progesterone and estrogen are present

Question 14

Posterior pituitary (general)

Answer 14

|| aka neurohypophysis
|| hypothalamus synthesizes small polypeptides (ADH and oxytocin) and sends them to posterior pituitary through axons for release into blood

Question 15

Oxytocin

Answer 15

|| small peptide, released by posterior pituitary
|| stimulates uterine contractions during pregnancy
|| stimulates milk ejection

Question 16

ADH (anti diuretic hormone)

Answer 16

|| aka vasopressin
|| increase permeability of kidney collecting ducts to water –> increasing fluid reabsorption –> increasing blood pressure
|| coffee and beer are ADH blockers (therefore increase urine volume)

Question 17

Adrenal cortex

Answer 17

|| outer portion of adrenal gland (that sits on top of the kidney)
|| secretes steroids once stimulated by peptide hormone ACTH
|| hormones:
Aldosterone (mineral corticoid)
Cortisol (glucocorticoid)
Small amount sex hormones

Question 18

Aldosterone

Answer 18

|| mineral corticoid (steroid), secreted by Adrenal Cortex
|| acts at distal tubule and collecting duct (kidney)
|| increase Na and Cl reabsorption, increase K and H secretion
|| net plasma solute concentration increase! therefore increase BP

Question 19

Gluconeogenesis

Answer 19

Formation of glucose and glycogen from amino acids, glycerol, lactic acid

In liver

Question 20

Cortisol

Answer 20

|| glucocorticoid (steroid), secreted by adrenal cortex
|| stress response:
Increase blood glucose concentration (by liver gluconeogenesis)
Increase fatty acid use for energy
Decrease immune system ability to fight infection
May have anti inflammatory capability
Increases non hepatic protein degradation

Question 21

Catecholamines (hormone)

Answer 21

|| tyrosine derivative, peptide hormones, secreted by adrenal medulla
|| norepinephrine, epinephrine
|| stress response, similar to sympathetic nervous system effects but longer lasting
| vasoconstriction for most internal organs and skin
| vasodilation (increased blood flow) for skeletal muscles

Question 22

T3, T4

Answer 22

|| tyrosine derivatives, lipid soluble, secreted by thyroid gland
|| secretion regulated by TSH (from anterior pituitary)
|| slow release into effector tissue (high affinity to plasma protein carriers)
|| number stands for iodines bound
|| affects transcription, increase basal metabolic rate

Question 23

Calcitonin

Answer 23

|| large peptide, secreted by thyroid gland
|| slightly decreases blood ca2+ by decreasing osteoclast activity and number
|| not super essential for blood ca regulation

Question 24

Insulin

Answer 24

|| peptide! secreted by pancreas
|| net effect: decrease blood glucose concentration
| inhibition glycogenolysis and gluconeogenesis in liver
| binding to extracellular receptors to initiate cascade that increases cell membrane permeability to glucose and amino acids
| increase protein synthesis, increase fat storage (adipose tissue), increase carbohydrate synthesis (in liver and skeletal muscle)
|| neurons don’t require insulin for glucose intake

Question 25

Glucagon

Answer 25

|| peptide! secreted by pancreas
|| net effect: increase blood glucose concentration
| stimulates gluconeogenesis and glycogenolysis in liver
| acts via second messenger cAMP
| in higher concentrations, stimulates triglyceride breakdown in adipose tissue

Question 26

Parathyroid glands (location)

Answer 26

|| 4 small glands located behind thyroid

Question 27

PTH (parathyroid hormone)

Answer 27

|| peptide! secreted by parathyroid glands
|| net effect : increase blood calcium concentration.
| increasing osteoclast resorption of calcium and phosphate ions
| increasing kidney reabsorption of calcium and excretion of phosphate
| increasing kidney production of vitamin D derived steroid that increases calcium and phosphate uptake from the gut