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Biochemistry Flashcards

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1
Q

Water balance in the body is controlled by

A

Anti-Diuretic Hormone (ADH) (aka Arginine Vasopressin)

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2
Q

ADH is produced by __________ and released by ____________

A

Hypothalamus
Posterior pituitary

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3
Q

ADH acts specifically in…..

A

Distal convoluted tubule (DCT) and collecting ducts (CD)

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4
Q

ADH acts through a ______________ to increase the transcription and insertion of ________________ to the apical membrane of the DCT and CD cells causing permeability of DCT and CD to _________

A

G-protein coupled receptor
Aquaporin–2 channels
Increase

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5
Q

Increased plasma osmolality would cause _______ release of ADH while decreased plasma osmolality would ________ ADH release

A

Increased
Decreased

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6
Q

Increase in DCT and CD permeability allows water to move ____________________, out of the nephron and back into the bloodstream, thus normalising ________________ and increasing ________________.

A

Down its concentration gradient
Plasma osmolality
Total blood volume

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7
Q

Large amount of ADH in volume leads to _____________ urine

A

Small volume of concentrated

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8
Q

Small amount of ADH in volume leads to _____________ urine

A

Large volume of diluted

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9
Q

Urine concentration/dilution measured as…

A

Urine osmolality

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10
Q

Concentrated urine has ________ osmolality while dilute urine has _______ osmolality

A

High
Low

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11
Q

Sodium balance in the body is mainly controlled by….

A

Mineralocorticoid activity of steroid

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12
Q

Mineralocorticoid activity is….

A

Na+ reabsorption in the renal tubules in exchange for K+/H+

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13
Q

Give examples of steroids with mineralocorticoid activity

A

Aldosterone (the main one)
Cortisol

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14
Q

Too much mineralocorticoid activity causes Na _______ while too little mineralocorticoid activity causes Na ______

A

Gain
Loss

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15
Q

Sodium (Na) is the most abundant cation in the _______________

A

Extracellular fluid (ECF) compartment

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16
Q

The normal plasma sodium concentration in ECF is __________, while the intracellular fluid (ICF) concentration is approximately _____________

A

135-145 mmol/L
10-12 mmol/L

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17
Q

Maintaining transmembrane concentration gradient of Na+ is necessary for……

A

Generating the resting membrane potential and for action potential propagation

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18
Q

Sodium is the main osmotic solute in the ECF, meaning that…..

A

Water travels in the direction of increasing sodium concentration via osmosis

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19
Q

Na+ intake determined by ____________ and excretion determined by _______________

A

Dietary intake and absorption in the colon and distal small bowel

Urinary excretion but also insensible losses, particularly in the sweat and faeces

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20
Q

Urinary sodium concentration is highly variable, depending on the……

A

Amount of reabsorption occurring in the nephrons

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21
Q

Majority of sodium reabsorption occurs in the…

A

Proximal Convoluted Tubule (PCT)

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22
Q

_______________________ allow for sodium reabsorption in the DCT

A

Apical Na+/Cl+ cotransporter

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23
Q

At any part in the nephron Na+ is driven across the basolateral membrane via…

A

Na-K-ATPase pumps

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24
Q

Which transporter is stimulated by aldosterone in order to increase Na reabsorption?

A

Apical ENaC in the collecting duct

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25
In renal artery stenosis, there is reduced perfusion of the kidneys due to the partial arterial occlusion. Which downstream hormone would increase in quantity as a result of this?
Aldosterone
26
What are the 2 kinds of stimuli for ADH release
Osmotic → in health Non-osmotic → in disease
27
Give examples of non-osmotic stimuli that cause ADH release
Hypovolaemia/hypotension Pain Nausea/vomiting
28
Hypotension and hypovolaemia stimulate _____________________
Activation of the sympathetic nervous system
29
Renal sympathetic nerve activity causes increased reabsorption of sodium in the PCT by activation of ___________________. This increases ___________, thereby ________________________, maintaining homeostasis.
a1 and a2 adrenoceptors Fluid retention Intravascular volume and blood pressure
30
Reduced renal perfusion and/or reduced sodium delivery to the nephron stimulates ________________________
Renin release from granular cells of the juxtaglomerular apparatus
31
Renin release leads to the production of ____________, which ____________.
Angiotensin II Stimulates aldosterone secretion.
32
RAAS activation causes angiotensin II to stimulate __________________ and aldosterone to _________________
The Na+/H+ antiporter in the PCT Increases the expression of ENaC in the CD
33
Raised blood volume stimulates myocytes to release ______ and _______ which promote _______________
ANP BNP Natriuresis (urinary excretion of sodium)
34
ANP and BNP act to reduce aldosterone secretion (from the adrenal glands) and renin secretion (from the juxtaglomerular apparatus), thereby _________________________
Decreasing sodium reabsorption in the DCT and CD
35
Addison's caused by ___________ thus not enough _______ made so decreased ________
Adrenal insufficiency Steroids Mineralocorticoid
36
Decreased mineralocorticoid activity in Addisons causes kidneys to be unable to _______ thus Na is loss from _______ decreasing the _______ volume meaning the patient is clinically dehydrated
Retain enough sodium ECF ECF
37
Why do patients with Addisons have excess pigmentation
Excess pigmentation reflects excess ACTH from pituitary ACTH molecule contains sequence for MSH within it ACTH is degraded by proteases eventually exposing MSH
38
ADH secreted in response to non-osmotic stimulus causes slow ___________ that is distributed over _________________ so patients clinical volume status is remarkable
Water retention All body compartments (ICF as well as ECF)
39
Diabetes insipidus is a....
Disruption of pituitary or pituitary stalk so ADH not secreted from posterior pituitary There is no ADH to act on kidneys to cause water to be reabsorbed Lots of pure water lost in urine so [Na] is high reflecting the H20 deficit
40
In diabetes insipidus, there is no...
ADH to act on kidneys to cause water to be reabsorbed
41
Mx of diabetes insipidus
Exogenous ADH (desmopressin) to replace ADH that the pituitary can’t make/release
42
Pituitary gland function is regulated by the _________ which is connected to it via the _________
Hypothalamus Pituitary stalk
43
Pituitary stalk comprises of the....
Portal blood capillaries and nerve fibres
44
What are the anterior pituitary hormones?
TSH (Thyroid Stimulating Hormone) ACTH (Adrenocorticotrophic Hormone) LH (Luteinising Hormone) FSH (Follicle stimulating hormona) GH (Growth hormone) Prolactin
45
What are the posterior pituitary hormones?
ADH Oxytocin
46
Function of TSH
Act on the thyroid gland to elicit secretion of thyroid hormones
47
Function of ACTH
Acts specifically on the adrenal cortex to elicit secretion of cortisol
48
Function of LH and FSH
Act cooperatively on the ovaries in women and the testes in men to stimulate sex hormone secretion and reproductive processes
49
Function of GH
Acts directly on many tissues to modulate metabolism Metabolic fuels (e.g. glucose, free fatty acids) in turn modify GH secretion
50
Function of prolactin
Acts directly on the mammary glands to control lactation Gonadal function is impaired by elevated circulating prolactin concentrations
51
Prolactin release is inhibited by _______ while its release is most strongly stimulated by_________
Dopamine aka PRL-inhibitory factor (PIF) Suckling
51
Prolactin (PRL) is produced by the ___________ of the anterior pituitary gland
Lactotroph cells
52
Causes of hyperprolactinoma
Stress Drugs Seizures Primary hypothyroidism Prolactinoma Idiopathic hypersecretion
53
Idiopathic hypersecretion of prolactin can be identified through....
A rise in serum prolactin following administration of TRH or metoclopramide
54
Serum potassium concentration is usually kept within....
3.5-5.3 mol/L
55
T or F: Potassium loses mirror potassium intake
True
56
Which 2 factors are important in determining potassium excretion
Glomerular filtration rate Plasma potassium concentration
57
Severe hyperkalaemia defined as...
>7.0 mmol/L
58
What can cause hyperkalaemia in the body
Decreased excretion of Na+ Increased intake of Na+ Redistribution of Na+ out of cells
59
Where is potassium most reabsorbed in the body?
Proximal Convoluted Tubule
60
Which channel is mainly responsible for potassium reabsorption in the thick ascending limb?
NKCC2 transporter
61
Which channel is mainly responsible for reabsorption of Potassium from the lumen into the cell in the distal convoluted tubule?
H+-K+-ATPase
62
Which channel is mainly responsible for the transportation of potassium ions into the cell from the bloodstream in the late distal convoluted tubule and collecting duct?
Sodium-Potassium ATPase
63
What is the mechanism of the NKCC2 cotransporter in the nephron?
It pumps Na+, K+ and 2Cl- into the cell from the lumen
64
What effect do renal outer medullar K+ (ROMK) channels have on K+ in the nephron?
Allow for movement of K+ into the lumen by creating a positive voltage which provides a driving force for the passive reabsorption of K+
65
Which metabolic abnormality is seen as a consequence of potassium depletion?
Hypokalaemia alkalosis
66
ECG changes seen with hyperkalaemia
Tall tented T waves Widening of the QRS complex Increased PR interval Flattened/absent P waves
67
What can cause decreased excretion of potassium
Renal failure Hypoaldosteronism → e.g. Addison's disease
68
High tubular K+ concentration stimulates _________________ which leads to an __________ of K+ channel on apical membrane. This results in an ___________ of K+ into the lumen
Na+/K+-ATPase Increased permeability Increased secretion
69
____________ stimulates ____________ in the basolateral membrane which stimulates ____________ & ____________ in the apical membrane, leading to increased K+ secretion.
Aldosterone Na+/K+-ATPase K+ channels & ENaCs
70
What can cause redistribution of potassium out of cells
Metabolic acidosis Potassium released from damaged cells Insulin deficiency Psudohyperkalaemia Hyperkalaemic periodic paralysis
71
Redistribution of K+ causes...
H+ is reabsorbed into the cells to try and decrease the pH, so K+ is excreted to maintain electrical equilibrium thus causing hyperkalaemia
72
What effect will alkalosis have on K+ in the extracellular fluid (ECF)?
Decrease in the concentration of K+ in the ECF
73
Where does insulin act in order to exert its effect on potassium levels in the blood?
Na+/K+-ATPase
74
Clinical features of hypothyroidism
Lethargy / tiredness Weight gain Cold intolerance Dryness and coarseness of skin and hair Constipation Bradycardia Subfertility Galactorrhoea
75
Causes of hypothyroidism
Autoimmune destruction of the thyroid gland (Hashimoto’s disease) Radioiodine or surgical treatment of hyperthyroidism TSH deficiency Congenital defect Iodine deficiency
76
Primary hypothyroidism is the...
Failure of the thyroid gland itself
77
T or F: The demonstration of an elevated TSH concentration is usually diagnostic of primary hypothyroidism
True
78
How to differentiate between primary and secondary hyperlipidaemia
Primary → Not due to an identifiable underlying disorder Secondary → Disorder is the manifestation of some other disease
79
Thyroid gland is responsible for...
Regulating the body’s metabolic rate via hormones it produces
79
Metabolic processes increased by thyroid hormones include....
Basal Metabolic Rate Gluconeogenesis Glycogenolysis Protein synthesis Lipogenesis Thermogenesis
80
How does thyroid glands increase metabolic processes
Increasing the size and number of mitochondria within cells Increasing Na-K pump activity Increasing the presence of β-adrenergic receptors in tissues such as cardiac muscle
81
What are the steps of thyroid hormone synthesis (ATE ICE)
Active transport of iodide into follicular cell Thyroglobulin is formed in follicular ribosome Exocytosisof thyroglobulin into the follicle lumen Iodination of the thyroglobulin Coupling of MIT and DIT Endocytiosis of iodinated thyroglobulin back into follicular cell
82
T or F: T3 and T4 are fat soluble
True
83
T3 and T4 are mostly carried by...
Thyronine binding globulin (TBG) and albumin → which are plasma proteins
84
What are the effects of cortisol?
Immunosuppression Anti-inflammatory Protein and afat metabolism Regulate mood, behaviour and cognition Lipolysis in adipose tissue Increase plasma glucose by breaking proteins into amino acids Stimulate gluconeogenesis in the liver Bone metabolism Regulate calcium absorption from GI tract
85
Cortisol MoA
Binds intracellularly to the glucocorticoid receptor (GR) in the cytoplasm

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