Renal 1 Flashcards
(25 cards)
What are the primary functions of the kidneys?
Regulate water and ion balance, remove waste, secrete hormones, and perform gluconeogenesis.
Which substances are primarily regulated by the kidneys?
Na+, K+, Ca2+, Cl−, HCO3−, H+, phosphates, and sulphates.
Which waste products are excreted by the kidney?
Urea, uric acid, creatinine, breakdown products of haemoglobin.
Which hormones are produced by the kidneys?
Erythropoietin, renin, and calcitriol (1,25-dihydroxyvitamin D).
What is the nephron?
The functional unit of the kidney, consisting of vascular and tubular components.
Where does filtration occur in the nephron?
At the renal corpuscle: the glomerulus and Bowman’s capsule.
What is the role of the proximal convoluted tubule?
Reabsorbs most of the filtered water, ions, and all glucose; secretes organic substances.
What happens in the loop of Henle?
Establishes a gradient for water reabsorption through countercurrent multiplication.
What is the role of the distal convoluted tubule and collecting duct?
Regulated reabsorption of Na+, K+, water, and H+ secretion; under hormonal control.
What are the three filtration barriers in the glomerulus?
Fenestrated endothelium, basement membrane, and podocyte filtration slits.
What type of charge do podocytes have and why?
Negative; to repel negatively charged proteins.
What determines GFR?
Hydrostatic and oncotic pressures, especially glomerular hydrostatic pressure.
How is GFR autoregulated?
By adjusting afferent/efferent arteriole diameter in response to blood pressure.
Where is most Na+ reabsorbed?
Proximal tubule (65–75%) via active transport.
What drives water and other solute reabsorption?
Na+ active transport establishes osmotic and electrical gradients.
Where is K+ primarily secreted?
In the distal nephron; regulated by aldosterone.
What is the consequence of hyperkalaemia?
Lowered resting membrane potential, arrhythmias, and possible death.
What does aldosterone do?
Increases Na+ reabsorption and K+ secretion in the distal nephron.
What is renal clearance?
The volume of plasma from which a substance is completely cleared per unit time.
How is glucose handled by the kidney?
It is freely filtered and fully reabsorbed until transport maximum is exceeded.
What happens when plasma glucose exceeds the renal threshold?
Glucose appears in urine (glycosuria).
What does PAH clearance indicate?
Renal plasma flow, as it is completely secreted.
What is the role of urea in the kidney?
Helps concentrate medullary interstitium for water reabsorption.
What are transport maximum (Tm) systems?
Saturable carriers used for reabsorbing/secreting substances like glucose, drugs, etc.
