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Physiology IIB (UofA) > Endocrine Physiology > Flashcards

Endocrine Physiology Flashcards

1
Q

What is autocrine signalling?

A

When there is a chemical effect on the same cell(s) that secreted the signalling molecule

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2
Q

What is paracrine signalling?

A

When a chemical is secreted and taken by neighbouring target cells

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3
Q

What is endocrine signalling?

A

When chemicals are released into the bloodstream to reach various targets throughout the body (hormones_

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4
Q

What types of hormones have internal receptors?

A
  • lipophilic ones ie steroids, THs
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5
Q

What types of hormones have external receptors?

A
  • hydrophilic ones ie peptides
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6
Q

Name the central endocrine glands.

A
  • Pituitary gland
  • Pineal gland
  • Hypothalamus
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7
Q

What is the difference between endocrine and exocrine structures within the body?

A

Endocrine

  • ductless
  • release hormones into surrounding fluid

Exocrine

  • have ducts
  • non-hormonal substances travel along ducts to reach other surfaces
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8
Q

Name two organs with both endocrine and exocrine function.

A

Stomach and Pancreas

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9
Q

What three factors stimulate hormone release?

A

Hormonal - stimulation from other hormones (known as tropic hormones)

Neural - stimulation comes from nerves fibres and APs

Humoral - stimulation due to certain levels of substances (eg. ions) in the blood

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10
Q

How can hormone interactions with the target cell be controlled?

A
  • Amount of hormone circulating in blood
  • Bond affinity with target cell receptor
  • Number of receptors that target cells has for hormone uptake
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11
Q

What is meant by permissiveness?

A

A hormone must be present to allow another hormone’s effects to be permitted (eg. cortisol is needed for adrenaline).

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12
Q

What is synergism?

A

When a combination of hormones produce an effect larger than the sum of their individual effects.

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13
Q

What is antagonism?

A

When a hormone reduces the effectiveness of another.

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14
Q

How are hormones cleared from the bloodstream?

A

Usually by liver and kidneys

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15
Q

What is the difference between hyper- and hypo-secretion?

A 
Hyper = too much
Hypo = too little
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16
Q

What is the difference between primary and secondary dysfunction?

A

Primary = there is an abnormality present within the gland

Secondary = Gland is normal but there is too little or too much stimulation

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17
Q

What are the three main hormone types and their derivatives?

A

Peptides - derived from amino acids
Steroids - derived from cholesterols
Amines - derives from tyrosine and tryptophan

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18
Q

What are 5 characteristics of peptide hormones?

A

Any of:

  • short half-life
  • lipophobic (hydrophilic)
  • stored in secretory vesicles
  • synthesised as pre-hormone in the ER
  • can’t diffuse into target cells (receptor needed)
  • usually rapid effects
  • common second messengers include cAMP and phosphoinositol
  • signal amplification occurs due to second messengers
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19
Q

What are 3 characteristics of amine hormones?

A
  • small in size (1-2 AAs)
  • Tyrosine (catecholamines and THs) or tryptophan (melatonin) derivatives
  • Can act either like peptides (catecholamines) or steroids (THs)
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20
Q

What are 5 characteristics of steroid hormones?

A
  • derived from cholesterol
  • lipophilic
  • often bound to carrier proteins to extend their half life
  • (most) receptors either in cytoplasm or nucleus
  • effects target cells by activation of target genes, altering protein synthesis
  • lipids synthesised in smooth ER of gonads, adrenals, placenta and skin
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21
Q

Define anabolism.

A

The synthesis of larger macromolecules.

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22
Q

Define catabolism.

A

The hydrolysis/oxidation of macromolecules.

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23
Q

What is glycogenesis and what is the consequence of this process?

A
  • conversion of glucose to glycogen

- decreases blood glucose

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24
Q

What is glycogenolysis and what is the consequence of this process?

A
  • conversion of glycogen to glucose

- increases blood glucose

25
Q

What is gluconeogenesis and what is the consequence of this process?

A
  • conversion of plasma AAs to glucose

- increases blood glucose

26
Q

What is protein synthesis and what is the consequence of this process?

A
  • conversion of AAs to proteins

- decreases blood AAs

27
Q

What is protein degradation and what is the consequence of this process?

A
  • conversion of proteins to AAs

- increases blood AAs

28
Q

What is lipogenesis and what is the consequence of this process?

A
  • conversion of fatty acids and glycerol to triglycerides

- decreases blood fatty acids

29
Q

What is lipolysis and what is the consequence of this process?

A
  • conversion of triglycerides to fatty acids and glycerol

- increases blood fatty acids

30
Q

How many molecules of ATP are needed to extract the energy stored in 1 glucose molecule?

A

32

31
Q

What occurs during the fed or absorptive state?

A
  • Excess glucose is stored in the liver and muscle as glycogen
  • If that is filled, glucose is transformed into fatty acids and glycerol
  • Proteins synthesised and excess circulating AAs are also converted to triglycerides
32
Q

What occurs during the fasted or post-absorptive state?

A
  • No net synthesis of gllycogen/fat/protein
  • catabolism of triglycerides
  • increase AA uptake into liver and gluconeogenesis maintains hepatic output of glucose
33
Q

What do pancreatic Beta-cells do?

A
  • Secrete insulin (dec. blood glucose)
34
Q

What do pancreatic Alpha-cells do?

A
  • secrete glucagon to encourage glycogen conversion to glucose (inc.blood glucose)
35
Q

What do pancreatic Delta-cells do?

A
  • secrete somatostatin (dec. gastric secretion)

- inhibits digestion of nutrients

36
Q

What do pancreatic polypeptide-cells do?

A
  • secrete PP which influences appetite
37
Q

Glucose entry into the body stimulates what hormone to be released?

A

Insulin - triggered by an increase in intracellular calcium levels (since Katp channels are inhibited)

38
Q

What is the function of the 4 glucose transporters?

A

GLUT1 = facilitates glucose movement across plasma membranes including the blood-brain barrier (insulin independent)

GLUT2 = principal transporter for transfer of glucose between liver and blood, and for renal glucose reabsorption (insulin independent)

GLUT3 = main transporter of glucose into neurons (insulin independent)

GLUT4 = regulated by insulin (dependent)

39
Q

What fraction of diabetes cases are of type I (insulin dependent DM)?

A

10%

therefore 90% attributed to type II

40
Q

List some complications of Diabetes Mellitus.

A
  • increased risk of heart attack, stroke, nephropathy and end-stage kidney disease, retinopathy, blindness, ischemia and gangrene
  • hypertension (secondary to renal injury)
  • athlerosclerosis
  • impaired cardiovasular reflexes and bladder control
  • decreased sensation in extremities
41
Q

What makes the posterior pituitary gland different from other endocrine glands?

A
  • it doesn’t synthesise hormones

Other fun facts include:

  • considered an extension of the hyothalamus
  • stores hormones formed in hypothalamic neurons
  • secretes hormones directly into the blood (eg ADH = anti-diuretic hormone, oxytocin)
42
Q

Why is anti-diuretic hormone important for the body and what triggers its release?

A

Why:

  • causes vasocontriction
  • increases water reabsorption
  • increases aldosterone (therefore increased conservation of sodium and water)

Triggers:

  • inc osmolarity
  • dec bp
  • inc adrenergic stressors
  • inc thirst (from CNS)
43
Q

What effect does oxytocin have on the rest of the body?

A
  • promotes lactation
  • involved in bonding & attachment
  • promotes contraction of uterine smooth muscle tissue
44
Q

True or False? Hormones combine with specific receptors (intra and extracellular) to activate a function within a target cell.

A

True.

45
Q

What type of hormones are lipophobic (hydrophilic)

A

Catecholamines and peptides.

46
Q

Estrogens, testosterone, cortisol and aldosterone are all derived from which precursor?

A
  • Cholesterol
47
Q

In the negative feedback response, does ACTH inhibit the inhibit cortisol secretion at the adrenal gland?

A

No, cortisol inhibits ACTH production by the anterior pituitary gland.

48
Q

True or False? Hypophysiotropic hormones always stimulate the release of anterior pituitary hormones.

A

False! Not always.

49
Q

How do hypophysiotropic hormones get to the anterior pituitary gland?

A

Via the hypothalamo-hypophyseal portal system

50
Q

What effect does GH have on the body?

A
  • dec glucose uptake for storage in cells
  • inc cell amino acid uptake
  • stimulates cell division
  • promotes bone growth until the epiphyseal plate is closed
51
Q

True or False? THs are synthesised within thyroglobulin molecules.

A

True :)

52
Q

Which hormone stimulated the productio of T3 and T4?

A
  • TSH = thyroid stimulating hormone
53
Q

True or False? There is a one-two hour supply of TH stored within the colloid in the lumen of the follicle.

A

False. There is an approx 2. month supply.

54
Q

What is another name for T4?

A

Throxine.

55
Q

What is DIT and how does it influence TH production?

A

DIT = diiodinated tyrosine

Combining two units of DIT makes T4 (DIT + MIT = T3)

56
Q

What stimulates catecholamine production in the adrenal medulla?

A

Direct sympathetic stimulation

57
Q

What hormone is produced in response to eating 20 jelly beans in the Monday afternoon prac session?

A

Insulin!

58
Q

What are four functions of cortisol?

A
  • dec glucose uptake into liver and muscle for storage
  • stimulates gluconeogenesis in liver
  • inc protein degradation
  • stimulates gastric acid secretion

Physiology IIB (UofA) (2 decks)

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