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Flashcards in Endocrine control review Deck (27)
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1

Define a hormone?

Blood borne chemical mediator released from endocrine glands that act on distant cells

2

Describe the major differences between the nervous system and the endocrine system?

3

How many hormones can be produced by one endocrine gland?

How many glands can one hormone be produced by?

Glands may produce multiple hormones

Multiple glands may produce one hormone 

4

What is a neurohormone?

What are the three major groups?

A neurocrine secreted into the bloodstream 

3 major groups: 

Hypothalamus > anterior pituitary

Hypothalamus > posterior pituitary

Catecholamines 

5

What is the difference between tropic and trophic hormones?

Tropic hormones control the secretion of another hormone

Trophic hormones stimulate growth and development 

6

How are tropic hormones usually named?

Usually have names that end in 'tropin' 

7

Describe the different ways by which hormones can be classified?

Source of hormone

Hormone structure (peptide, amine, steroidP

Hormone solubility (hydrophilic or lipophilic)

Binding of receptor type 

 

8

Describe the differences between peptide, steroid and amine hormones?

9

Describe the difference in synthesis and storage between peptide, steroid and amine hormones?

Peptide: made in advance, stored in secretory vesicles

Steroid: synthesised on demand from precursors

Catecholamines: made in advance, stored in secretory vesicles

Thyroid hormones: made in advance, precursor stored in secretory vesicles

10

Describe the difference in release mechanism between peptide, steroid and amine hormones?

Describe the reason for each mechanism.

Peptide: exocytosis (lipophobic)

Steroid: simple diffusion (lipophilic)

Catecholamines: exocytosis (lipophobic)

Thyroid hormones: simple diffusion (lipophilic)

11

Describe the difference in transport in the blood between peptide, steroid and amine hormones?

Peptide: dissolved in plasma

Steroid: bound to carrier proteins

Catecholamines: dissolved in plasma

Thyroid hormones: bound to carrier proteins

12

Describe the half-lives of peptide, steroid and amine hormones?

Peptide: short

Steroid: long

Catecholamines: short

Thyroid hormones: long

13

Describe the location of receptors for peptide, steroid and amine hormones? 

Explain the reason for each.

Peptide: cell membrane (lipophobic)

Steroid: cytoplasm or nucleus (lipophilic)

Catecholamines: cell membrane (lipophobic)

Thyroid hormones: nucleus (lipophilic)

14

Describe the response to receptor-ligand binding in peptide, steroid and amine hormones?

Peptide: activation of second messenger systems (membrane receptor)

Steroid: activation of genes for transcription and translation (cytoplasmic/nuclear receptors)

Catecholamines: activation of second messenger systems (membrane receptor)

Thyroid hormones: activation of genes for transcription and translation (nuclear receptors)

15

Give examples of peptide, steroid and amine hormones?

Peptide: insulin, PTH

Steroid: oestrogen, cortisol

Catecholamine: adrenaline, noradrenaline

Thyroid hormones: thyroxine

 

16

Briefly describe the process of peptide hormone synthesis?

Preprohormone synthesised by ribosomes > ER lumen > cleaved to prohormone > Golgi complex > secretory vesicles with prohormone formed > enzymes cleave into active hormone > exocytosis

17

What is the parent compound for all steroid hormones?

Cholesterol

18

Describe the action of steroid and thyroid hormones after receptor binding?

Alter gene expression and produce new proteins 

19

Describe the influences on plasma hormone concentration?

Rate of secretion by endocrine gland

Rate of metabolic activation

Extent of binding to plasma proteins 

Rate of metabolic inactivation and excretion 

 

20

Describe the different mechanisms of hormone removal?

Steroid: conjugation > urine and bile

Amines: circulating degrading enzymes

Large peptides: receptor-mediated endocytosis

Small peptides: kidneys

21

Describe the different mechanisms of regulation of hormones secretion?

Negative feedback systems: long loops and short loops

Positive feedback systems 

Neuroendocrine reflexes 

Diurnal and circadian rhythms 

22

How is regulation of cortisol release achieved?

According to diurnal and circadian rhythm 

23

Describe permissive regulation of hormone secretion?

First hormone cannot exert its effects without presence of second hormone

eg. cortisol and adrenaline 

24

Describe the difference between a primary and secondary endocrine disorder?

Primary: abnormal endocrine gland

Secondary: normal endocrine gland, something wrong elsewhere in pathway

25

List some possible causes of decreased or increased hormone activity?

DECREASED: hyposecretion, increased removal from blood, lack of receptors, lack of enzyme for cell response

INCREASED: hypersecretion, decreased plasma protein binding, dcreased removal from blood

26

Describe the general approach to treatment for decreased and increased hormone activity?

Decreased: hormone administration

Increased: tumour removal, inhbiting drugs

27