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Biomed 2 > Topic 9: Endocrine System > Flashcards

Topic 9: Endocrine System Flashcards

1
Q

What are the 3 functional classes of hormones (not the protein one)

A
  • releasing hormone: released from hypothalamus
  • stimulating / tropic hormones: from pituitary glad to act on another endocrine gland
  • non-tropic hormones: from endocrine glad to target cell
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2
Q

What are the 3 chemical classes of hormones? give some examples of each!

A
  • Amino hormones (derived from tyrosine)
    Examples: adrenaline, noradrenaline, thyroxine (T4 & T3)
  • Peptide and Protein hormones (encoded by genes, may undergo modifications). defined as hormones with glycoprotein subunit. Hydrophilic
  • Steroid hormones (derived from cholesterol via enzymatic reactions). Cholesterol converted to pregnenolone which moves between mitochondria and ER - is the precursor to all steroids
    Examples: Glucocorticoids, androgens, oestrogens, progestins, mineralocorticoids
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3
Q

Steroid hormones are a)________ that can cross membranes freely. They aren’t stored in endocrine glands but are released as made. They travel in b)________ with steroid-binding c)________

  • globulins
  • lipophilic
  • the blood
A

a) lipophilic
b) the blood
c) globulins

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4
Q

Binding to cell surface receptors releases second messengers within the cell. Give some examples of second messengers

A
  • cAMP / cGMP (adenylate cyclase converts ATP to cAMP)
  • Phospholipids diacylglycerol and inositol triphosphate (DAG / IP3)
  • Calcium
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5
Q

Second messengers create phenotypic changes in target cells. Give 3 mechanisms that can cause these changes

A
  • Alter phosphorylation of proteins
  • Alter permeability of membranes
  • Indirectly influence gene expression
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6
Q

Basic/simple hormone regulation is determined by 3 factors, what are they? (rates of ………. pretty obvious)

A
  • rate of production
  • rate of delivery
  • rate of degradation and elimination
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7
Q

There are 3 methods of hormone regulation, name em (feedbacks)

A
  • Basic / simple
  • Negative feedback (most common (e.g. thyroid via feedback to hypothalamus)
  • Positive feedback (used when signal amplification is needed
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8
Q

Name the associated hormones and target area involved the the HPA beginning with these hormones released from the hypothalamus:

a) Thyrotropin RH
b) Corticotrophin RH
c) Gonadotrophin RH

A

a) Thyroid stimulating H –> Thyroid (T3 /T4)
b) Adreno-Corticotrophic H –> Adrenal cortex (cortisol)
c) Luteinising H –> Ovary/Testes (Oestrogen / Testosterone)

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9
Q

Synthesis of tri-iodothyronine (T3) and thyroxine (T4) occurs by the iodination of a)________. Once synthesised its stored extracellularly in b)_________ on the surface of thyroglobulin molecules. More c)____ is secreted than d)____, but (c) is converted to (d) in the body

  • T3
  • Thyrosine
  • Follicular cells
  • T4
A

a) Thyrosine
b) follicular cells
c) T4
d) T3

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10
Q

List the following steps in the correct order:

a) TSH released into blood stimulates thyroid follicular cells
b) Low blood levels of T3 and T4 stimulate release of TRH
c) Elevated T3 inhibits release of TRH and TSH
d) TRH transported to anterior pituitary gland, stimulates release of TSH
e) T3 and T4 released into blood by follicular cells

A

b)
d)
a)
e)
c)

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11
Q

Note:

  • Osmoreceptors detect change in osmolality (as small as 1%)
  • Signal sent to Vasopressinergic neuron
  • Vasopressin & Neurophysin II produced
  • Released from posterior pituitary
A

when plasma osmolality exceeds threshold -> increase in vasopressin secretion

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12
Q

Match the receptor to the second messenger and the functions:

a) V1a
b) V1b (V3)
c) V2
d) OT

  • G0-protein phospholipase C
  • G0-protein kinase C
  • G0-protein kinase A
  • G0-protein phospholipase A2, C & D

Functions
1. Blood vessel constriction
2. Increases urea re-absorption
3. Adrenal angiotensin II secretion
4. Increases glomerular filtration rate
5. Liver glycogenolysis
6. Platelet adhesion
7. Stimulates pituitary ACTH secretion
8. Increases NaCl reabsorption
9. Myometrial contraction
10. Specific sexual, affiliative and maternal behaviours

A

a) G-protein phospholipase A2, C & D. (1, 3, 5, 6)
b) G-protein phospholipase C. (7)
c) G-protein kinase A. (2, 4, 8)
d) G-protein kinase C. (9, 10)

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13
Q

What is the function of a baroreceptor in the circulatory system

A

Sense a decrease blood volume / pressure.
Leads to vasopressin secretion.
Less sensitive than osmoreceptors (~10% change)

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14
Q

How do the following factors affect vasopressin?

a) High osmolarity
b) High blood pressure
c) Low blood volume
d) Nicotine
e) Nausea
f) EtOH
g) Angiotensin

  • Stimulate
  • Inhibit
A

a) Stimulate
b) Inhibit
c) Stimulate
d) Stimulate
e) Stimulate
f) Inhibit
g) Stimulate

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15
Q

Diabetes insipidus is caused by the inability to secrete or respond to vasopressin, leading to excretion of large volumes of urine, dehydration and thirst. Causes of this can be a) neurogenic or b) nephrogenic. What is the difference?

A

a) Neurogenic - hyposecretion of ADH (due to head trauma, tumour, damage etc.)
b) Nephrogenic - kidneys do not respond to ADH

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16
Q

When blood sugar rises, the a)_______ cells in the pancreas secrete b)_________ that causes enhanced uptake of glucose, converting it to c)________ and storing it in the liver. When blood sugar is low, d)_______ cells in the pancreas release e)_______ causing the liver to break down (c) and release glucose into the blood.

  • Insulin
  • Glycogen
  • Beta
  • Glucagon
  • Alpha
A

a) Beta
b) Insulin
c) Glycogen
d) Alpha
e) Glucagon

17
Q

Match the hormone and cell type to the principal action:

a) Glucagon (alpha cells)
b) Insulin (beta cells)
c) Somatostatin (delta cells)
d) Pancreatic polypeptide (F cells)

  • Decrease in secretion of insulin and glucagon and slows absorption of nutrients from gastrointestinal tract
  • Increase in blood glucose levels by glycogenesis (breakdown of glycogen into glucose in liver), gluconeogenesis and releasing glucose into blood
  • Decrease in somatostatin secretion, gallbladder contraction and secretion of pancreatic enzymes
  • Decrease in blood glucose levels by glycogenesis (accelerating transport of glucose into cells, converting glucose to glycogen)
A

a) Increase in blood glucose levels by glycogenesis (breakdown of glycogen into glucose in liver), gluconeogenesis and releasing glucose into blood

b) Decrease in blood glucose levels by glycogenesis (accelerating transport of glucose into cells, converting glucose to glycogen)

c) Decrease in secretion of insulin and glucagon and slows absorption of nutrients from gastrointestinal tract

d) Decrease in somatostatin secretion, gallbladder contraction and secretion of pancreatic enzymes

18
Q

Diabetes mellitus is a group of disorders caused by an inability to produce or secrete or use a)________.
This can cause an b)________ of blood glucose (hyperglycemia) and loss of glucose in the urine (c)________) due to d)_________ causing e+f) _________ + ___________.

  • Polydispsia (excessive eating)
  • Glucosuria
  • Insulin
  • Polyphagia (excessive eating)
  • Polyuria (excessive urine)
  • Elevation
A

a) insulin
b) elevation
c) glucosuria
d) polyuria
e+f) Polydispsia + Polyphagia

19
Q

What is the difference between type I and type II diabetes?

A

Type I: Insulin-dependent
- antibodies against beta cells in pancreas
- body cannot produce its own insulin
- cells use fatty acids for ATP production
- Weight loss, cardiovascular production, kidney failure, cataracts

Type II: Non-insulin-dependent
- peripheral cells become resistant to insulin so pancreas has to pump out more
- can be regulated by diet control, exercise etc

20
Q

Oxytocin binds to:

a) mRNA
b) G-protein coupled receptor
c) ionotropic receptor
d) Nuclear receptor

A

b

21
Q

Vasopressin is a:

a) amino acid derivate

b) peptide

c) glycoprotein

d) mineralocorticoid

e) sex steroid

A

B - peptide

Biomed 2 (16 decks)

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