Intro To Endocrinology

Question 1

Hormones secreted from the hypothalamus (5)

Answer 1

Thyrotropin releasing hormone (TRH)

Corticotropin releasing hormone (CRH)

Gonadotropin releasing hormone (GnRH)

Somatostatin

Dopamine

Question 2

Hormones secreted from the anterior pituitary gland (7)

Answer 2

Thyroid stimulating hormone (TSH)

Follicle stimulating hormone (FSH)

Luteinizing hormone (LH)

Adrenocorticotropic hormone (ACTH)

Melanocytes stimulating hormone (MSH)

Growth hormone (GH)/growth hormone releasing hormone (GHRH)

Prolactin

Question 3

Hormones secreted from the posterior pituitary gland (2)

Answer 3

Antidiuretic hormone (ADH)

Oxytocin

Question 4

Hormones secreted from the thyroid gland (3)

Answer 4

Triiodothyronine (T3)

Tyroxine (T4)

Calcitonin

Question 5

Hormones secreted from the parathyroid gland (1)

Answer 5

Parathyroid hormone (PTH)

Question 6

Hormones secreted from the pancreas (2)

Answer 6

Insulin

Glucagon

Question 7

Hormones secreted from the adrenal medulla (2)

Answer 7

Norepinephrine

Epinephrine

Question 8

Hormones secreted from the kidney (2)

Answer 8

Renin

1,25-dihydroxycholecalciferol

Question 9

Hormones secreted from the adrenal cortex (3)

Answer 9

Cortisol

Aldosterone

Adrenal androgens

Question 10

Hormones secreted from the testes (1)

Answer 10

Testosterone

Question 11

Hormones secreted from the ovaries and corpus luteum (2)

Answer 11

Estradiol

Progesterone

Question 12

Hormones secreted from the placenta (4)

Answer 12

Human chorionic gonadotropin (hCG)

Estriol

Progesterone

Human placental lactogen (hPL)

Question 13

Three classes of hormones

Answer 13

Protein and peptides

Amines

Steroids

Question 14

Protein and peptide hormones are synthesized as _____ or a _____(not active).

____ is removed in the ER to produce a prohormone.

They are packed into ____ and cleaved by ______ generating the active form.

Answer 14

Larger polypeptides

Preprohormone

Signal peptide

Vesicles

Proteolytic enzymes

Question 15

Protein and peptide hormones are stored in secretory vesicles until _____.

Stimulus for exocytosis?

Answer 15

Endocrine cell is stimulated

Increase of intracellular Ca caused by membrane depolarization
OR
Activation of G-protein-coupled receptor followed by increase in CAMP and activation of PKA

Question 16

Steroid hormones are synthesized and secreted by ____.

Examples?

Modifications of cholesterol?

Answer 16

Adrenal cortex, gonads, corpus luteum

Cortisol, aldosterone, estradiol, estriol, progesterone, testosterone, 1,25-dihydroxycholecalciferol

Remove/add side chains, hydroxylation of steroid nucleus, aromatization of the steroid nucleus

Question 17

Steroid hormones are synthesized from ____ which comes from what two sources?

Answer 17

Cholesterol

80% taken up as LDL particles through receptor mediated endocytosis

De novo synthesis from acetyl coenzyme A

Question 18

Action of a steroid hormone that allows it to modulate gene transcription by interaction with intracellular nuclear receptors

Answer 18

Genomic action

Question 19

Action of a steroid hormone that allows it to have rapid steroid action through receptor mediated or direct steroid membrane interactions

Answer 19

Nongenomic action

Question 20

Amine hormones are derived from ____.

What are their two groups?

Answer 20

Tyrosine

Catecholamines and thyroid hormones

Question 21

These amine hormones are synthesized in the cytosol and secretory granules

They act though cell-membrane associated receptors

Answer 21

Catecholamines

Question 22

These amine hormones are synthesized by the thyroid gland and stored as _____ in follicles within the gland.

They cross the cell membrane and act through nuclear receptors

Answer 22

Thyroid hormones

Thyroglobulin in follicles

Question 23

Thyroid (amine) hormones have the ___ half life and ___ clearance.

Steroid hormones?

Protein hormones?

Answer 23

Longest; smallest

Middle; biggest

Shortest; middle

Question 24

Secretion of hormones is regulated by two mechanisms?

____ to an endocrine cell increases or decreases hormonal secretion

____ some element of the physiological response feeds back, directly or indirectly, on the endocrine gland and changes secretion rate

Answer 24

Neuronal input

Feedback mechanism (positive and negative)

Question 25

Describe negative feedback: Long-loop feedback? Short-loop feedback? Ultra short-loop feedback?

Answer 25

Hormone released from the 3rd tier (peripheral endocrine gland) feeds all the way back to the 1st tier (hypothalamus) and 2nd tier (pituitary gland) Hormone secreted from 2nd tier feeds back to 1st tier Gland inhibits its own secretion

Question 26

Major endocrine axis

Answer 26

Hypothalamus-pituitary-adrenal gland axis (HPA) Hypothalamus-pituitary-thyroid gland axis (HPT) Hypothalamus-pituitary-gonads axis (HPG)

Question 27

Negative feedback in which the secretion of a hormone is stimulated or inhibited by a a change in the level of a specific extracellular signal Example?

Answer 27

Response-driven negative feedback Insulin regulates blood glucose levels; blood glucose concentration turns on or off insulin secretion

Question 28

How are the secretions from the first tier of the endocrine axes regulated (hypothalamus)? What are its two major inputs and what do they do?

Answer 28

Descending and ascending neuronal inputs Suprachiasmatic nucleaus (SCN): impose a circadian rhythm on the secretion of hypothalamic releasing hormones and endocrine axes Pineal gland: releases melatonin which feedbacks info about day/night to the SCN Physiological stress influences hormone release from the hypothalamus

Question 29

Receptors have a ____ to the hormone actions through a _____ complex. The responsiveness of a target tissue to a hormone is expressed in the ____ relationship. Sensitivity occurs when a hormone concentration produces ___ of the maximal response.

Answer 29

Specificity Hormone-receptor complex Dose-response relationship 50%

Question 30

How do you up-regulate a hormone?

Answer 30

Increase the number of receptors, increase the sensitivity of the target tissue when hormone levels are low, decrease the degradation of existing receptors, activate receptors

Question 31

How do you down-regulate a hormone?

Answer 31

Reduce the number of receptors, decrease the sensitivity of the target tissue when hormone levels are high, increase the degradation of existing receptors, inactivate/desensitize receptors

Question 32

What are the five major mechanisms of hormone action of target cells?

Answer 32

Adenylyl cyclase Phospholipase C Steroid hormone Guanylyl cyclase Tyrosine kinases

Question 33

Adenylyl cyclase mechanism of hormone action: 1st messenger? Primary effector? 2nd messenger? Secondary effector?

Answer 33

Hormones (ACTH, LH, FSH, TSH, glucagon) Adenylyl cyclase cAMP PKA

Question 34

Phospholipase C mechanism of hormone action: 1st messenger? Primary effector? 2nd messenger? Secondary effector?

Answer 34

Hormones (GnRH, TRH, GHRH, oxytocin) Phospholipase C IP3/DAG/Ca PKC or calmodulin

Question 35

Steroid hormone mechanism of hormone action: 1st messenger? Primary effector? 2nd messenger? Secondary effector?

Answer 35

Hormones (thyroid hormones, glucocorticoids, aldosterone, estrogen, testosterone) No second messenger Act through cytosolic/nuclear receptors (hormone binding end and a DNA binding end) Hormone-receptor complex acts as transcription factor that regulates the rate of transcription of a gene

Question 36

Guanylyl cyclase mechanism of hormone action: 1st messenger? Primary effector? 2nd messenger? Secondary effector?

Answer 36

Hormones (atrial natriuretic peptide/ANP, NO) Guanylate cyclase cGMP PKG

Question 37

Tyrosine kinase mechanism of hormone action has two major categories How do they work? What are examples of each?

Answer 37

Receptor tyrosine kinases (have intrinsic tyrosine kinase activity within the receptor; when activated, the intrinsic tyrosine kinase phosphorylation itself and other proteins; examples are nerve growth factor, epidermal growth factor receptors, insulin, and insulin-like growth receptors) Tyrosine kinase-associated receptors (associate non-covalently to proteins that have tyrosine kinase activity; example is JAK)