Endocrine Control Review

Question 1

What is endocrinology?

Answer 1

Study of homeostatic mechanisms controlled by hormones

Question 2

What is a hormone?

Answer 2

Blood-borne chemical mediator released from endocrine glands > act on distant target cells

Question 3

What must a target cell have to respond to a hormone?

Answer 3

Receptor for that hormone

Question 4

Compare the nervous and endocrine systems in terms of anatomical arrangement

Answer 4

Nervous system: wired system

Endocrine system: wireless system

Question 5

Compare the nervous and endocrine systems in terms of the type of chemical messenger

Answer 5

Nervous system: neurotransmitters released into synaptic cleft
Endocrine system: hormones released into blood

Question 6

Compare the nervous and endocrine systems in terms of the distance of action of chemical messenger

Answer 6

Nervous system: very short distance

Endocrine system: long distance

Question 7

Compare the nervous and endocrine systems in terms of the means of specificity of action on target cells

Answer 7

Nervous system: dependent on close anatomical relationship

Endocrine: dependent on specificity of target cell binding

Question 8

Compare the nervous and endocrine systems in terms of speed of response

Answer 8

Nervous system: rapid

Endocrine system: slow

Question 9

Compare the nervous and endocrine systems in terms of duration of action

Answer 9

Nervous system: brief

Endocrine system: long

Question 10

Do endocrine glands only produce one hormone?

Answer 10

No, may produce multiple

Question 11

Are hormones produced by only one endocrine gland?

Answer 11

No, may be produced by multiple

Question 12

Can hormones have more than one target and function?

Answer 12

Yes

Question 13

Can a single cell/organ be influenced by more than one hormone?

Answer 13

Yes

Question 14

can the same chemical messenger be both a hormone and neurotransmitter?

Answer 14

Yes

Question 15

What are autocrine signals?

Answer 15

Act on same cell that secreted them

Question 16

What are autocrine signals for?

Answer 16

Self-regulation

Question 17

What are paracrine signals?

Answer 17

Secreted by one cell and diffuse to adjacent cells

Question 18

What are paracrine signals for?

Answer 18

Response propagation

Question 19

What kinds of permeability/solubility do hormones have?

Answer 19

Lipophilic = hydrophobic
Hydrophilic = lipophobic

Question 20

What is a neurohormone?

Answer 20

Neurocrine secreted into bloodstream

Question 21

What are the major groups of neurohormone systems?

Answer 21

Hypothalamus > anterior pituitary
Hypothalamus > posterior pituitary
Catecholamines made by modified adrenal medulla neurons

Question 22

What is a trophic hormone?

Answer 22

Controls secretion of another hormone

Question 23

What is the mechanism of action of peptide hormones and catecholamines?

Answer 23

Bind to surface receptors
Generate intracellular 2nd messenger signal
Hydrophilic = lipophobic

Question 24

What is the mechanism of action of steroid hormones?

Answer 24

Alter gene expression and production of new proteins
Takes time
Lipophilic = hydrophobic

Question 25

What hormone group do thyroid hormones behave like?

Answer 25

Steroids

Question 26

What influences plasma hormone concentration?

Answer 26

Rate of secretion by endocrine gland = major factor Rate of metabolic activation - for few Extent of binding to plasma proteins - for lipophilic Rate of metabolic inactivation and excretion

Question 27

How are hormones generally removed?

Answer 27

Liver > kidney > urine

Question 28

How are steroid hormones removed?

Answer 28

Conjugation > urine (and bile)

Question 29

How are amines removed?

Answer 29

Specific circulating degrading enzymes

Question 30

How are large peptides removed?

Answer 30

Receptor-mediated endocytosis

Question 31

How are smaller peptides removed?

Answer 31

Kidneys

Question 32

What is the long loop of negative feedback control?

Answer 32

Hormone acts on hypothalamus and pituitary to decrease secretion of trophic hormone

Question 33

What is the short loop of negative feedback control?

Answer 33

Anterior pituitary acts on hypothalamus to decrease secretion of trophic hormone

Question 34

Which is more common in negative feedback control: long loop, or short loop?

Answer 34

Long loop

Question 35

What regulates hormone secretion?

Answer 35

``` Neuroendocrine reflexes Feedback Diurnal and circadian rhythms - Pineal gland - Suprachiasmatic nucleus Down-regulation of receptors - Endocytosis - Target cell desensitisation Antagonism Synergy Permissive ```

Question 36

What is permissive in regulation of hormone secretion?

Answer 36

First hormone can't exert effects without presence of second hormone

Question 37

What can cause decreased hormone activity?

Answer 37

Hyposecretion Increased removal from blood Abnormal tissue response

Question 38

What can cause increased hormone activity?

Answer 38

Hypersecretion Decreased plasma protein binding Decreased removal from blood

Question 39

What can cause hyposecretion?

Answer 39

``` Primary = gland abnormal Secondary = abnormal trophic hormone ```

Question 40

What can cause hypersecretion?

Answer 40

``` Primary = gland abnormal Secondary = excessive stimulation ```

Question 41

What can cause an abnormal tissue response, leading to decreased hormone secretion?

Answer 41

Lack of receptors | Lack of enzyme for cell response

Question 42

What can cause decreased removal from the blood, leading to increased hormone secretion?

Answer 42

Damaged liver and kidneys - Decreased inactivation - Decreased excretion