Endocrine Control Review Flashcards Preview

MD1 Endocrine > Endocrine Control Review > Flashcards

Flashcards in Endocrine Control Review Deck (42):
1

What is endocrinology?

Study of homeostatic mechanisms controlled by hormones

2

What is a hormone?

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

3

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

Receptor for that hormone

4

Compare the nervous and endocrine systems in terms of anatomical arrangement

Nervous system: wired system
Endocrine system: wireless system

5

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

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

6

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

Nervous system: very short distance
Endocrine system: long distance

7

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

Nervous system: dependent on close anatomical relationship
Endocrine: dependent on specificity of target cell binding

8

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

Nervous system: rapid
Endocrine system: slow

9

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

Nervous system: brief
Endocrine system: long

10

Do endocrine glands only produce one hormone?

No, may produce multiple

11

Are hormones produced by only one endocrine gland?

No, may be produced by multiple

12

Can hormones have more than one target and function?

Yes

13

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

Yes

14

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

Yes

15

What are autocrine signals?

Act on same cell that secreted them

16

What are autocrine signals for?

Self-regulation

17

What are paracrine signals?

Secreted by one cell and diffuse to adjacent cells

18

What are paracrine signals for?

Response propagation

19

What kinds of permeability/solubility do hormones have?

Lipophilic = hydrophobic
Hydrophilic = lipophobic

20

What is a neurohormone?

Neurocrine secreted into bloodstream

21

What are the major groups of neurohormone systems?

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

22

What is a trophic hormone?

Controls secretion of another hormone

23

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

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

24

What is the mechanism of action of steroid hormones?

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

25

What hormone group do thyroid hormones behave like?

Steroids

26

What influences plasma hormone concentration?

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

27

How are hormones generally removed?

Liver > kidney > urine

28

How are steroid hormones removed?

Conjugation > urine (and bile)

29

How are amines removed?

Specific circulating degrading enzymes

30

How are large peptides removed?

Receptor-mediated endocytosis

31

How are smaller peptides removed?

Kidneys

32

What is the long loop of negative feedback control?

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

33

What is the short loop of negative feedback control?

Anterior pituitary acts on hypothalamus to decrease secretion of trophic hormone

34

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

Long loop

35

What regulates hormone secretion?

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

36

What is permissive in regulation of hormone secretion?

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

37

What can cause decreased hormone activity?

Hyposecretion
Increased removal from blood
Abnormal tissue response

38

What can cause increased hormone activity?

Hypersecretion
Decreased plasma protein binding
Decreased removal from blood

39

What can cause hyposecretion?

Primary = gland abnormal
Secondary = abnormal trophic hormone

40

What can cause hypersecretion?

Primary = gland abnormal
Secondary = excessive stimulation

41

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

Lack of receptors
Lack of enzyme for cell response

42

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

Damaged liver and kidneys
- Decreased inactivation
- Decreased excretion