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March Exams > Chem Path > Flashcards

Chem Path Flashcards

0
Q

Functions of cortisol

A
  • antagonises insulin
  • causes proteolysis (prod of amino acids)
  • anti-inflam
  • suppresses immune system
  • antagonises vit D to reduce calcium absorption
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1
Q

Functions of aldosterone

A
  • promotes sodium and water retention

- k and h excretion

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2
Q

Hormones produced by the cortex of the adrenal gland

A

Corticosteroids
Glomerulosa - mineralocorticoids - aldosterone
Fasiculata - glucocorticoids - cortisol
Reticularis - androgens - DHEA

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3
Q

Hormones produced by adrenal medulla

A

Catecholamines (E and NE)

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4
Q

Describe steroid synthesis

A
  • produced from cholesterol
  • rate limiting step = chol side-chain cleaved to pregnenolone (stim by ACTH)
  • hydroxylations require cyt-p450 in mitochondria
  • 17 and 21 hydroxylations occur in sER
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5
Q

Why is aldosterone not affected by decrease in ACTH?

A

Stimulated mainly be ang2 and k

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6
Q

Characteristics of CBG

A
  • made by liver
  • high affinity
  • low capacity
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7
Q

Characteristics of albumin

A
  • low affinity

- high capacity

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8
Q

Why does aldosterone have a shorter half life.

A

Not bound to plasma protein

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9
Q

3 catecholamine hormones

A
  • dopamine
  • epinephrine
  • norepinephrine
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10
Q

Action of alpha adrenergic receptors

A
  • vasoconstriction
  • decreased insulin release
  • sweating
  • glycogenolysis
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11
Q

Action of beta adrenergic receptors

A
  • vasodilation
  • increased HR
  • intestinal smooth muscle relaxation
  • bronchodilation
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12
Q

Synthesis of catecholamines

A
  • from phenylalanine
  • rate limiting. = tyrosine to DOPA
  • hormones in adrenal medulla are complexed to chromogranin proteins in granules
  • nerve stim causes granule release
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13
Q

How are catecholamines degraded?

A
  • catechol-O-methyl transferase (COMT) - methylation

- mono amine oxidase (MOA) - deamination

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14
Q

Pattern of inheritance of CAH

A

Autosomal recessive inborn errors of steroid hormone biosynthesis

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15
Q

Most common defect in CAH

A

21 hydroxylase

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16
Q

Mechanism of 21 hydroxylase deficiency

A
  • can’t synthesize cortisol so increased ACTH (adrenal hyperplasia)
  • accumulation of 17- hydroxyprogesterone (shunting to androgen synthesis)
  • elevated 17OHP in serum confirms
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17
Q

3 forms of CAH

A
  • simple virilising
  • severe salt-losing
  • non-classical
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18
Q

Characteristics of simple virilising form

A
  • mild enzyme defect

- adequate cortisol and aldosterone production

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19
Q

Characteristics of sever salt-losing form

A
  • severe enzyme defect
  • potential adrenal crisis due to inadequate aldosterone
  • hypotension, shock, hyperkalaemia
  • boys more at risk
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20
Q

Characteristics of non classical form

A
  • very mild defect
  • no neonatal masculinization
  • young women present with menstrual irregularities, infertility and hisuitism
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21
Q

Treatment of CAH

A
  • cortisol and fludrocortisone

- monitor by measuring 17OHP and androgens

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22
Q

Characteristics of 11hydroxylase deficiency

A
  • accumulated 11 deoxycortixosterone has mineralocorticoids activity
  • salt retaining
  • hypertension and hypokalaemia
  • ambiguous genitalia
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23
Q

Diagnosis of CAH

A
  • elevated serum 17OHP or 11DOC
  • decreased serum cortisol
  • elevated serum ACTH
  • elevated serum testosterone
  • karyotyping
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24
Q

Definition of primary Addison’s disease

A
  • impaired capacity to secrete cortisol and aldosterone
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25
Q

Definition of secondary Addison’s disease

A
  • lack of ACTH
  • cortisol deficiency
  • intact aldosterone e
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26
Q

Features of an addisonian crisis

A
  • hypotension
  • circulatory shock
  • abdominal pain
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27
Q

Clinical features of Addison’s

A
  • fatigue
  • muscle weakness
  • orthostatic hypertension
  • pigmentation (excess ACTH)
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28
Q

Biochem features of Addison’s

A

Aldosterone deficiency

  • Na and water loss in urine
  • hyperkalaemia and metabolic acidosis

Cortisol deficiency

  • inability to excrete water load
  • hypoglycemia
29
Q

Key diagnostic features of Addison’s

A
  • orthostatic hypotension
  • low Na
  • high k
30
Q

Hormonal changes at puberty

A
  • adrenarche (adrenal androgen secretion)
  • decreased sensitivity of axis
  • increased ovarian oestradiol secretion
31
Q

Events of peri-menopause

A
  • FSH rises 1-2 years before
  • LH initially unchanged
  • oestrogen normal til few months before
32
Q

Why more free testosterone in pcos?

A

Androgens and insulin suppress hepatic shbg synthesis

33
Q

Causes of hisuitism

A
  • idiopathic
  • drugs (anabolic steroids)
  • ovarian (pcos)
  • adrenal (CAH)
  • Cushing’s syndrome
34
Q

Commonest tumours associated with tumour lysis syndrome

A
  • burkitts and ALL

- solid tumours that are bulky with extensive metastasis

35
Q

Modified Howard definition of TLS

A

2 or more of the following metabolic abnormalities Occurring simultaneously within 3 days prior and up to 7 days after initiation of treatment

  • hyperuricaemia
  • hyperkalaemia
  • hyperphosphataemia
  • hypocalcaemia
36
Q

Two factors in TLS that can cause renal failure

A
  • hyperuricosuria (acute Uric acid nephropathy)

- hyperphosphataemia (calcium phosphate crystals in renal parenchyma)

37
Q

Prevention of TLS

A
  • suspect and anticipate
  • adequate IV hydration
  • prophylactic allopurinol
38
Q

Treatment f TLS

A
  • watch renal function
  • hydration
  • reduce Uric acid with allopurinol
  • correct electrolyte abnormalities
39
Q

3 pathways supplying cells with bases, nucleosides and nucleotides

A
  • salvage
  • degradation
  • de novo synthesis
40
Q

Define gouty to phi

A

Depositions of mono sodium urate crystals in joints, cartilage, bones, skin and other sites

41
Q

Definition of gout

A

Acute painful arthritis in a single joint due to deposition of Uric acid crystals

42
Q

Diagnosis of gout

A
  • clinical features
  • Uric acid crystals in joint fluid aspirate is definitive
  • elevated plasma Uric acid is suggestive
43
Q

Causes of gout

A
  • under excretion (renal insufficiency)
  • overproduction (malignancy, obesity)
  • over-consumption (meat, alcohol)
44
Q

Treatment of gout

A
  • colchicine to reduce acute pain
  • allopurinol to reduce Uric acid formation
  • uricosurics to increase Uric acid excretion
45
Q

Definition of multiple myeloma

A

Malignant proliferation of a clone of plasma cells

46
Q

Pathogenesis of multiple myeloma

A

When one clone of plasma cells becomes malignant, the expansion of this clone suppresses the formation of other clines
- overproduction of a single monoclonal antibody

47
Q

Features of myeloma

A
  • bone marrow infiltration (osteolytic lesions, bone pain)
  • hypercalcaemia (due to osteoclast activity)
  • bone marrow suppression (anaemia)
  • monoclonal protein production (elevated ESR, hyper viscosity)
48
Q

Lab features of myeloma

A
  • high total protein
  • monoclonal antibody on serum protein electrophoresis
  • suppression of other immunoglobulins
  • sometimes free light chains in urine (bench jones proteinuria)
49
Q

Hormones that increase plasma glucose

A
  • glucagon
  • adrenaline
  • GH
  • cortisol
50
Q

Hormones that decrease plasma protein

A
  • insulin
51
Q

Diagnosis of HbA1c

A

Non-enzymatic covalent glycation of the N terminal valine on the b-chain of Hb

52
Q

Methods of diabetes diagnosis

A
  • fasting plasma glucose levels
  • glucose tolerance test
  • hba1c
53
Q

Methods of monitoring diabetes

A
  • plasma glucose
  • urine glucose
  • plasma ketones
  • urine ketones
  • hba1c
54
Q

Diagnosis of DKA

A
  • decrease PH

- increase glucose and ketones

55
Q

Diagnosis of honk

A
  • increase glucose and osmolarity
  • no ketones
    PH decrease
56
Q

3 thyroid hormones

A
  • thyroxine
  • triiodothyronine
  • calcitonin
57
Q

Thyroid hormone function

A
  • bind in nucleus
  • necessary for physical growth and development
  • oxygen consumption and ATP hydrolysis increased in mitochondria
  • effects on hormones (enhances insulin action)
58
Q

Factors that increase TBG

A

Oral contraceptive pill

Pregnancy

59
Q

Factors that decrease TBG

A

Protein losing states
Malnutrition
Corticosteroids

60
Q

Tumour marker for thyroid cancer

A

Thyroglobulin

61
Q

Tumour marker for medullary thyroid cancer

A

Calcitonin

62
Q

Changes seen in sick euthyroid syndrome

A
  • decreased peripheral conversion of T4 to T3
  • changes in conc/affinity of binding proteins
  • disturbances in axis
63
Q

Common causes of Addison’s disease

A
  • autoimmune
  • TB
  • Neoplastic infiltration
  • haemochromatosis
  • adrenoleukodystrophy
  • CAH
64
Q

Functions of oestrogen

A
  • female secondary sex characteristics
  • bone growth
  • uterine thickening
  • breast development
65
Q

Functions of progesterone

A
  • promotes secretions of uterus
  • implantation of ovum
  • maintenance of early pregnancy
66
Q

How can oestrogen be carried in blood?

A
  • 60% albumin
  • 38% SHBG
  • 2% free
67
Q

When is progesterone at max and what is it used for?

A

At day 21

Tests ovulation

68
Q

Causes of amenorrhea

A
  • disorders of uterus
  • disorders of the ovary (hypergonadotropic)
  • disorders of pituitary (hypogonadotropic)
  • CNS disorders
69
Q

Features of PCOS

A
  • menstrual irregularities
  • hyperandrogenism
  • obesity
  • insulin resistance
  • multiple follicles
70
Q

Hormone levels in pcos

A
  • androgens elevated
  • oestradiol normal
  • LH high
  • FSH normal

March Exams (14 decks)

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