Histology Flashcards
(34 cards)
What are the functions of the kidney and urinary tract?
Maintain water and electrolyte homeostasis, body fluid osmolarity and acid-base balance.
Excrete toxic metabolic waste products (mainly urea and creatinine).
Act as an endocrine gland, producing renin and erythropoietin.
What is the kidney covered by?
Strong capsule of dense collagen fibres.
What is the renal hilum?
Site of entry of renal artery and exit of renal vein and ureter.
What is the renal medulla composed of?
Medullary pyramids (8-18 per kidney) with apices pointing toward the hilum (called papillae) ending on the minor calyces.
What is considered a kidney lobe?
A medullary pyramid and its associated cortical tissue.
What is the kidney capsule made of?
Collagenous fibres that are continuous with the connective tissue lining the renal sinus.
What is a nephron?
The basic functional unit of a kidney.
What is a nephron composed of?
Renal corpuscle.
Renal tubules.
What is the function of the renal corpuscle?
Production and collection of the glomerular filtrate.
What is a renal corpuscle composed of?
A tuft of capillaries (the glomerulus) surrounded by a cup of simple squamous epithelium at the blind end of the nephron which the capillaries invaginate into (Bowman’s capsule).
What are the 2 cell layers that separate blood from glomerular filtrate in the renal corpuscle?
Capillary endothelium.
Specialised epithelium that lies on top of the glomerular capillaries made up of podocytes.
What is the mesangium?
A specialised connective tissue, composed of mesangial cells, which sits at the core of the renal corpuscle.
What are the 3 components of the glomerular filter?
Fenestrated endothelium of the capillary wall.
The thick basement membrane (shared by endothelium and podocyte).
Filtration slits between pedicels.
What is the function of the proximal convoluted tubule?
Reabsorption of water, proteins, amino acids, carbohydrates and glucose.
- 70% of sodium (active transport) and water (diffusion) is reabsorbed.*
- Almost all glucose and amino acids reabsorbed (by co-transport).*
What is the function of the loop of Henle?
Creation of a hyperosmotic environment in the medulla.
What is the function of the distal convoluted tubule?
Acid-base and water balance (absorption of water, sodium and bicarbonate; excretion of potassium and hydrogen ions).
What is the renal medulla composed of?
Parallel tubules.
Loops of Henle.
Collecting ducts.
Looping vascular network.
What is the composition of a loop of Henle?
A thick descending limb.
A thin descending limb which makes a hairpin turn and journeys back out of the medulla as a thin ascending limb.
Thick ascending limb.
What are the thick limbs of the loop of Henle lined by?
Simple cuboidal epithelium.
What are the thin limbs of the loop of Henle lined by?
Simple squamous epithelium.
What are vasa recta?
Loops of thin-walled blood vessels that dip down into the medulla from above and then climb back up to the cortex to supply the loops of Henle.
What are the main histological differences between the proximal and distal convoluted tubules?
Distal convoluted tubules (DC) are slightly smaller and have a more obvious luminal margin because they have only sparse apical microvilli.
What is the role of aldosterone in the distal convoluted tubule?
Reabsorption of Na+ in the DCT is controlled by the hormone aldosterone which is secreted by the adrenal cortex and results in greater Na+ and water retention and therefore it increases blood pressure.
What is the function of the collecting ducts?
Reabsorption of water under the control of ADH.
