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Phase 2a Medicine (JH) > Endocrinology > Flashcards

Endocrinology Flashcards

1
Q

Endocrinology is the study of what four things?

A
  1. Hormones and their respective glands.
  2. Their receptors.
  3. Intracellular signalling pathway.
  4. Associated diseases.
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2
Q

How are endocrine glands different to exocrine glands?

A

Endocrine glands are ductless so release hormones directly into the blood. Exocrine glands pour secretions through a duct.

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3
Q

Give four important physiological characteristics that endocrine glands are responsible for.

A

Rapid adaptive changes.
Integration of whole body physiology.
Chronic maintenance of metabolic environment.
Communication for multicellular organisms.

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4
Q

Give three examples of an exocrine gland.

A

Submandibular glands.
Parotid.
Pancreas.

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5
Q

Endocrine hormones have effects where in relation to their release?

A

Distant sites.

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6
Q

Paracrine hormones have effects where in relation to their release?

A

Neighbouring cells.

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7
Q

Autocrine hormones have effects where in relation to their release?

A

The same cell.

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8
Q

Give three characteristics of water-soluble hormones.

A

Transported unbound.
Bind to surface receptor of cells.
Short half-life.

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9
Q

Give three characteristics of fat-soluble hormones.

A

Transported bound.
Diffuse into cells.
Long half-life.

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10
Q

Give three characteristics of peptide hormones.

A

Stored in secretory granules.
Released in pulses/bursts.
Created by tissue/circulating enzymes.

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11
Q

Describe the conversion involved in the synthesis of peptide hormones.

A

Preprohormone to prohormone.

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12
Q

Describe the conversion involved in the packaging of peptide hormones.

A

Prohormone to hormone.

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13
Q

Give an example of a peptide hormone.

A

Insulin.

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14
Q

Name the amino acid that catecholamines are derived from.

A

L-tyrosine.

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15
Q

L-tyrosine can be derived from dietary sources or synthesis from which compound?

A

Phenylalanine.

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16
Q

Describe the steps involved in the conversion of phenylalanine to adrenaline/epinephrin.

A 
Phenylalanine. 
L-tyrosine. 
L-DOPA. 
Dopamine. 
Noradrenaline/norepinephrine. 
Adrenaline/epinephrine.
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17
Q

What is COMT?

A

Catechol-O-methyl transferase.

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18
Q

COMT converts adrenaline and noradrenaline to what?

A

Metanephrine and normetanephrine respectively.

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19
Q

Why are metanephrine and normetanephrine useful compounds?

A

They can be measured in the serum so can be used as indicators or adrenaline and noradrenaline activity.

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20
Q

Amines bind to which receptors?

A

Alpha receptors or beta receptors.

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21
Q

Give four possible effects when an amine binds to an alpha receptor.

A

Vasoconstriction.
Bowel muscle contraction.
Sweating.
Anxiety.

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22
Q

Give four possible effects when an amine binds to a beta receptor.

A

Vasodilation.
Increase in heart rate.
Increase in heart contractility.
Relaxation of bronchial smooth muscle.

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23
Q

Why must iodothyronines be bound to a protein?

A

They aren’t water soluble.

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24
Q

Name the protein that 99% of iodothyronines are bound to?

A

Thyroid-binding globulin (TBG).

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25
Q

Give the full name of hormones T3 and T4.

A

Triiodothyronine (T3).

Thyroxine (T4).

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26
Q

How many molecules of iodine is bound to thyroxine in thyroxine?

A

Four.

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27
Q

Explain why T4 is a reservoir for T3.

A

T4 can be converted to T3 under the action of deiodinases.

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28
Q

How is the activity and concentration of T3 and T4 different?

A

T3 is more active.

T4 is more produced.

29
Q

What is the primary feature of thyroid microanatomy?

A

Follicles.

30
Q

Describe the structure of thyroid follicles.

A

A protein-rich core of colloid surrounded by follicular cells.

31
Q

Describe how follicular cells trap iodide.

A

By actively cotransporting iodide with Na+ across its basolateral membrane.

32
Q

Colloid contains large amounts of which protein?

A

Thyroglobulin.

33
Q

Thyroglobulin is produced by which cells?

A

Follicular cells.

34
Q

Iodide is transported into the colloid where it undergoes what change?

A

Rapid oxidisation to iodine.

35
Q

Newly formed iodine in the colloid binds to what?

A

Tyrosine residues.

36
Q

Where are tyrosine residues found?

A

On thyroglobulin molecules.

37
Q

Iodine binds to tyrosine residues under the action of which enzyme?

A

Thyroid peroxidase.

38
Q

Which two compounds can be formed from the binding of iodine to tyrosine residues?

A

Monoiodotyrosine (T1).

Diiodotyrosine (T2).

39
Q

What must happen before T1/T2 join with T2 to produce thyroid hormone?

A

T2 and T1 must be cleaved from their tyrosine backbones, but remain attached to thyroglobulin.

40
Q

How are thyroid hormones transported out of the colloid during secretion?

A

Follicular cells engulf the colloid by endocytosis.

41
Q

How are T3 and T4 released from thyroglobulin during secretion?

A

Proteolysis of thyroglobulin by lysosomes.

42
Q

Describe the solubility of vitamin D.

A

Fat-soluble.

43
Q

Vitamin D is transported by which protein?

A

Vitamin D binding protein.

44
Q

Give four examples of adrenocortical and gonadal steroids that bind to cytoplasm receptors to bring about an effect.

A

Cortisol.
Aldosterone.
Progesterone.
Testosterone.

45
Q

How do hormones that bind to cytoplasm receptors stimulate transcription?

A

The receptor-hormone complex enters the nucleus and bind to the glucocorticoid response element.

46
Q

Name three types of hormone secretion.

A

Continuous release.
Pulsatile.
Circadian rhythm.

47
Q

Growth hormone and GHRH are inhibited by what?

A

Somatostatin.

48
Q

What is the function of glucose?

A

Energy source.

49
Q

Why is the brain solely dependent on glucose for energy?

A

Free fatty acids cannot cross the blood-brain barrier.

50
Q

How does the brain differ from other tissues in its glucose uptake?

A

Does not depend on insulin.

51
Q

Name the two hormones involved in the regulation of blood glucose concentration.

A

Insulin and glucagon.

52
Q

What should blood glucose levels be under normal conditions?

A

3.5-8mmol/L.

53
Q

Insulin is produced by which cells?

A

Beta cells.

54
Q

What is the function of insulin?

A

To reduce blood glucose concentration.

55
Q

Describe how insulin functions to reduce blood glucose concentration?

A

Insulin binds to insulin receptors which causes glucose transporter-containing vesicles to fuse with the membrane of cells and allow glucose to enter.

56
Q

Name the glucose transporter that is promoted by insulin.

A

GLUT-4.

57
Q

Glucose enters cells via GLUT-4 transport proteins by what process?

A

Facilitated diffusion.

58
Q

Insulin is coded for on which chromosome?

A

Chromosome 11.

59
Q

Describe the process involved in the production of insulin.

A

Proinsulin (insulin precursor) is cleaved from its c-peptide and the alpha and beta chains of insulin are joined together. Insulin is packaged into secretory granules.

60
Q

Describe how insulin acts in the liver to reduce blood glucose concentration.

A

Insulin promotes the conversion of glucose to glycogen and inhibits the production of glucose by gluconeogenesis.

61
Q

What is the action of insulin when maximum glucose storage is reached?

A

Insulin promotes glycolysis and the production of pyruvate, which can be converted to fatty acids and stored in adipose tissue.

62
Q

Give examples of stimulatory factors for insulin secretion.

A

Glucagon and cortisol.
Increased fatty acid or amino acid concentration.
Acetylcholine.

63
Q

Describe how glucagon and cortisol stimulate insulin secretion.

A

The stimulatory effect of glucagon and cortisol is indirect by increasing glucose levels.

64
Q

Describe why acetylcholine is a good stimulatory factor for insulin secretion.

A

Acetylcholine is released from activation of the parasympathetic nervous system during digestion to reduce the concentration of recently absorbed glucose.

65
Q

Give to inhibitory factors of insulin secretion.

A

Norepinephrine and somatostatin.

66
Q

Describe why norepinephrine is a good inhibitory factor for insulin secretion.

A

Norepinephrine is released from the activation of the sympathetic nervous system during stressful situations when readily available glucose is needed.

67
Q

Glucagon is produced by which cells?

A

The alpha cells of the pancreas.

68
Q

What is the function of glucagon?

A

To increase blood glucose concentration when fasting or during physical activity.

Phase 2a Medicine (JH) (7 decks)

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