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Endocrinology > Intro > Flashcards

Intro Flashcards

1
Q

What is a circadian rhythm?

A

Physiological changes that occur normally as part of a 24 hour period

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2
Q

What are some examples of things that change in a circadian rhythm? How do they change?

A

Body temperature - decreases with sleep

Cortisol - increases with sleep

Melatonin - increases with sleep

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3
Q

What is the biological clock?

A

Small group of neurones in the suprachiasmatic nucleus in the brain

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4
Q

What are the inputs to the biological clock?

A

Changes in the environment to do with

  • light
  • temperature
  • eating/drinking pattern
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5
Q

What is the function of the biological clock?

A

Responsible for putting into effect the circadian rhythm

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6
Q

What causes jet lag?

A

Mismatch of environmental inputs

and the biological clock output

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7
Q

What secretes melatonin?

A

Pineal gland

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8
Q

What is the function of melatonin?

A

Sets the biological clock

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9
Q

What is negative feedback?

A

Change away from set point causes response to reverse the direction of change

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10
Q

What is a classic example of negative feedback in endocrinology?

A

The HP axis

involves short loops, long loops and ultra short loops of negative feedback

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11
Q

What is positive feedback?

A

Change away from set point causes response to give more change in same direction

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12
Q

When is positive feedback used?

A

When a rapid change is desirable

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13
Q

What are some examples of positive feedback?

A

Blood clotting (e.g. thrombin burst)

Ovulation

Ferguson reflex - oxytocin and uterine contractions during childbirth

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14
Q

Which is more common - positive or negative feedback?

A

Negative feedback

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15
Q

What is responsible for detecting osmotic pressure of blood plasma?

A

Osmoreceptors

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16
Q

Where are osmoreceptors located?

A

Hypothalamus

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17
Q

What is normal blood osmolality?

A

275 - 295 mOsm/kg

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18
Q

What happens in response to osmoreceptors in the hypothalamus detecting high blood osmolality?

A

Posterior pituitary secretes more ADH

Increased thirst

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19
Q

What is the effect of increased ADH secretion?

A

Increased reabsorption of water from urine into blood

in collecting ducts in kidney

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20
Q

What effect does increased reabsoprtion of water from urine have on urine?

A

Smaller volume of urine produced

and urine is more concentrated

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21
Q

What happens in response to osmoreceptors in the hypothalamus detecting low blood osmolality?

A

Posterior pituitary secretes less ADH

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22
Q

What is the effect of decreased ADH secretion?

A

Decreased reabsorption of water from urine into blood

in collecting ducts in kidney

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23
Q

What effect does decreased reabsorption of water from urine have on urine?

A

Larger volume of urine produced

and urine is more dilute

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24
Q

What is the endocrine system?

A

Collection of glands throughout the body

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25
Q

What are hormones?

A

Chemical signals produced in endocrine glands
or tissues
travel through bloodstream
cause an effect on other tissues

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26
Q

Do only endocrine glands produce hormones?

A

No

other organs and tissues are release hormones

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27
Q

Which other organs or tissues produce hormones? What hormones?

A

Heart - ANP, BNP

Liver - IGF-1

Stomach - Ghrelin

Adipose - Leptin

Kidney - EPO, renin, calcitriol

28
Q

What are the glands of the endocrine system?

A

Hypothalamus
Pituitary gland
Pineal gland

Thyroid gland
Parathyroid glands

Thymus gland

Adrenal glands
Pancreas

Ovaries
Testes

29
Q

What is neurocrine secretion?

A

Hormone originates in neurone
transported down axon
released into bloodstream
carried to distant target cells

30
Q

What are the similarities between the nervous and endocrine systems?

A

Neurones and endocrine cells are capable of secreting

Neurones and endocrine cells can be depolarised

Some molecules are both hormones and neurotransmitters

Mechanism of action involves interaction with specific receptors on target cells

Both control homeostasis

31
Q

What do neurones secrete? What do endocrine cells secrete?

A

Neurones - neurotransmitters

Endocrine cells - hormones

32
Q

Which system communicates faster - nervous or endocrine?

A

Nervous system

33
Q

What is an example of a molecule that’s both a neurotransmitter and a hormone?

A

Dopamine = Prolactin inhibiting hormone

34
Q

What are the four categories of hormones?

A

Peptide/polypeptide

Amino acid derivates

Glycoproteins

Steroids

35
Q

What is the most common category of hormone?

A

Peptide/polypeptide

36
Q

What are some examples of peptide/polypeptide hormones?

A

Insulin
Glucagon

Growth hormone

37
Q

How do peptide/polypeptide hormones react to water?

A

Hydrophilic

water-soluble

38
Q

What are amino acid derived hormones synthesised from specifically?

A

AROMATIC amino acids

39
Q

What are some examples of amino acid derived hormones and their corresponding amino acid?

A

Tyrosine

  • adrenaline
  • noradrenaline
  • thyroid hormone

Tryptophan
-melatonin

40
Q

Which of the amino acid derived hormones are water-soluble?

A

Adrenaline

Noreadrenaline

41
Q

Which of the amino acid derived hormones are lipid-soluble?

A

Thyroid hormone

42
Q

What is the structure of glycoprotein hormones?

A

Large protein molecules - often subunits of them

with carbohydrate side chain

43
Q

What are some examples of glycoprotein hormones?

A

LH - leuteinising hormone
FSH - follicle stimulating hormone

TSH - thyroid stimulating hormone

44
Q

How do glycoprotein hormones react to water?

A

Hydrophilic

Water soluble

45
Q

What are steroid hormones derived from?

A

Cholesterol

46
Q

What are some examples of steroid hormones?

A

Cortisol

Aldosterone

Testosterone

47
Q

How do steroid hormones react to water?

A

Hydrophobic

insoluble in water, lipid-soluble

48
Q

Which hormones travel in the blood as part of the solution?

A

Peptides

Glycoprotein hormones

Some amino acid-dervied hormones

49
Q

How do insoluble hormones travel in the blood?

A

Bound to specific carrier proteins

50
Q

What are the roles of carrier proteins?

A

Increase solubility of hormone in blood plasma

Increase half life

Form a reserve of hormone

51
Q

Is the free form or the protein-bound form of the hormone biologically active?

A

Free form

52
Q

How are the levels of free hormone and protein-bound bound hormone controlled?

A

Free hormone + carrier protein = protein-bound hormone

dynamic equilibrium between the two

53
Q

What are the factors determining levels of hormone in the blood? Which is the most regulated?

A

Rate of production
Rate of delivery - blood flow to tissue
Rate of degradation

Most regulated is rate of production

54
Q

How are hormones degraded?

A

Metabolised and excreted from body

55
Q

At what range of concentration do hormones circulate in the blood?

A

Picomolar

basically very low concentrations

56
Q

How do hormones have effects on some cells and not others?

A

Target cells have specific receptors for the hormone

Non-target cells have no receptors for the hormone
so are unaffected by the hormone

57
Q

Where are receptors for water-soluble hormones located?

A

Cell surface receptors

58
Q

What are the two types of cell-surface receptors for water-soluble hormones?

A

GPCRs

Tyrosine kinase receptors

59
Q

How do tyrosine kinase receptors work?

A

Ligand binds to receptor

receptor dimerises
autophosphorylation of specific tyrosines
recruitment of adapter proteins, signalling complex
activation of protein kinase…

60
Q

Where are receptors for lipid-soluble hormones located?

A

Intracellular

  • cytoplasm
  • nuclear
61
Q

How do lipid-soluble hormones enter the cell?

A

Diffuse across plasma membrane

62
Q

What does a newly formed cytoplasmic receptor-hormone complex do?

A

Translocate into nucleus

bind to DNA

63
Q

Where are nuclear receptors found?

A

In the nucleus
pre-bound to DNA
hormone response elements - promoter region of gene that’s regulated by the hormone

64
Q

What effect does hormone binding to a nuclear receptor have?

A

Relieves suppression of gene transcription

that the bound receptor was responsible for

65
Q

What is the result of cytoplasmic receptor-hormone complex and nuclear receptor-hormone complex?

A

Gene transcription
new protein produced
gives cell response

66
Q

What is the nature of endocrine system signals? And nervous system signals?

A

Endocrine system - chemical

Nervous system - chemical and electrical

Endocrinology (14 decks)

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