54 - Endocrine Control Review

Question 1

Six general principles of hormones

Answer 1

• Endocrine glands may produce multiple hormones (pituitary)
• Hormones may be produced by multiple endocrine glands (sex
steroids)
• Hormones may have more than one target and function (sex steroids,
GH)
• Rate of secretion of some hormones varies over time in a cyclic pattern
(sex steroids)
• Single cell/ organ may be influenced by more than one hormone
(pancreas, reproductive)
• Same chemical messenger may be hormone or neurotransmitter (NE)

Question 2

Neurohormones

Answer 2

Neurocrine that is released into the bloodstream.

Question 3

Three major groups of neurohormones

Answer 3

1) Hypothalamus→ Anterior
Pituitary.
2) Hypothalamus→ Posterior
Pituitary.
3) Catecholamines (made by
modified adrenal medulla
neurons).

Question 4

Neurotransmitters

Answer 4

A neurocrine molecule secreted to a target cell

Question 5

Tropic hormones
1
2

Answer 5

1) A hormone that controls the secretion of another hormone (trophic usually stimulates growth & development)
2) Often (not always) have names that end with -tropin
Eg. Thyrotropin (TSH), Corticotropin, ACTH, etc.

Question 6

Simple endocrine reflex

Answer 6

Stimulus leads to endocrine gland releasing endocrine into blood, which affects target.

Question 7

Where are catecholamine receptors located on cells?

Answer 7

Cell surface

Question 8

Synthesis and storage of peptide hormones

Answer 8

Made in advance, stored in secretory vesicles

Question 9

How are peptide hormones released from cells?

Answer 9

Exocytosis

Question 10

Transport of peptide hormones in blood

Answer 10

Dissolved in plasma

Question 11

Location of peptide hormone receptors

Answer 11

Cell surface

Question 12

General target response of peptide hormones

Answer 12

Modification of existing proteins, induction of new protein synthesis

Question 13

Examples of peptide hormones

Answer 13

Insulin, parathyroid hormone

Question 14

Synthesis of steroid hormones

Answer 14

Synthesised on demand form precursors (cholesterol)

Question 15

Release of steroid hormones from parent cell

Answer 15

Simple diffusion

Question 16

Transport of steroids in blood

Answer 16

Bound to carrier proteins

Question 17

Half life of steroid hormones

Answer 17

Long

Question 18

Amine hormones

Answer 18

Catecholamines and thyroid hormones

Question 19

Synthesis and release of amine hormones

Answer 19

Both made in advance.
Catecholamines stored in secretory vesicles.
Thyroid hormone prohormones stored in secretory vesicles.

Question 20

Precursor to amine hormones

Answer 20

Tyrosine

Question 21

Half life of amine hormones

Answer 21

Catecholamines are short.

Thyroid hormones are long.

Question 22

Location of amine hormone receptors

Answer 22

Catecholamines in cell membrane.

Thyroid hormones in nucleus.

Question 23

Which other hormones do thyroid hormones behave like?

Answer 23

Like steroids

Question 24

Things influencing plasma hormone concentration
1
2
3
4

Answer 24

1) Rate of hormone secretion by the endocrine gland (major factor, for all hormones)
2) Rate of metabolic activation of hormone (for a few hormones)
3) Extent of binding to plasma proteins (for lipophilic hormones)
4) Rate of metabolic inactivation and excretion (for all hormones)

Question 25

Removal of steroid hormones

Answer 25

Conjugation and excretion in urine and bile

Question 26

Removal of amine hormones

Answer 26

Specific circulating degrading enzymes

Question 27

Removal of large peptide hormones

Answer 27

Receptor mediated endocytosis and recycling

Question 28

Removal of most small hormones

Answer 28

Kidneys

Question 29

Two broad negative feedback systems

Answer 29

Long-loops (back up system) Short-loops

Question 30

What triggers LH surge in menstruation?

Answer 30

High oestrogen levels (if oestrogen levels don't rise enough, don't get LH surge)

Question 31

``` Regulation of hormone secretion 1 2 3 4 ```

Answer 31

1) Down‐regulation 2) Antagonism 3) Synergism 4) Permissive

Question 32

Down-regulation in hormone secretion

Answer 32

– Endocytosis | – Target cell desenitisation

Question 33

Antagonism in regulating hormone secretion

Answer 33

– Act together but act in opposite directions (insulin & glucagon) – Allows fine tuning

Question 34

Synergism in regulating hormone secretion

Answer 34

– Multiple stimuli and effect is more than additive (glucagon, cortisol & adrenaline regulating blood glucose; reproductive)

Question 35

Permissive hormone regulation

Answer 35

– First hormone cannot exert effects without presence of second hormone (cortisol & adrenaline)

Question 36

Primary endocrine disorders

Answer 36

Secreting gland of hormone is abnormal

Question 37

``` Disorders of decreased hormone activity 1 2 3 4 ```

Answer 37

– Hyposecretion • Primary (gland abnormal) • Secondary (normal gland; abnormal tropic hormone) – Increased removal from blood – Abnormal tissue response • Lack of receptors • Lack of enzyme for cell response – Treatment: hormone administration

Question 38

``` Disorders of increased hormone activity 1 2 3 4 ```

Answer 38

– Hypersecretion • Primary (gland abnormal) • Secondary (normal gland; excessive stimulation) – Decreased plasma protein binding – Decreased removal from blood • Decreased inactivation • Decreased excretion – Treatment: Tumor removal, inhibiting drugs