Renal 1: Anatomy and Filtration Flashcards
Where are the kidneys located?
They are deep to the 12th rib. Left kidney is slightly higher than the right due to downward projection of liver above it.
What are the primary functions of the kidneys?
They control the composition of blood and body fluids via urine formation, the fluid volume and osmolarity, and pH of EC fluid, including blood. IT IS THE PRIMARY EXCRETORY ORGAN - always working to clean blood.
What major vessels supply the kidneys with blood?
The renal arteries stem from the aorta, delivering a large amount of oxygenated blood to the kidneys straight from the heart; the renal veins drain into the Inferior Vena Cava.
Describe the urine collection system from minor calyces to the ureter.
Urine is created in pyramids then drains into the calyceal system: each minor calyx drains one pyramid; multiple minor calyces drain into a major calyx and urine converges into renal pelvis which narrows down into the ureter which takes urine to bladder. (Not passive - all lined with smooth muscle)
What makes up a nephron and what is it’s purpose?
The tubule and glomerulus. The nephron is the functional unit of the kidney (1 million in each kidney): filters blood and produces urine. Urine exits the collecting duct thru the papilla.
What makes up the tubule?
Proximal and distal convoluted tubules, the loop of Henle, and the collecting tubule/duct
What is the Bowman’s Capsule?
A cup like extension of the tubule that forms a filtration barrier over the capillaries of the glomerulus. Has visceral and parietal layers (invaginated).
What are the 2 different kinds of nephrons?
Superficial (cortical): short loops of Henle, focused on reabsorp/secret. About control.
Juxtamedullary: long loops of Henle. About concentration (Loop of H’s job is concentration)
What are the cellular differences between the convoluted tubules and the loop of Henle?
Convoluted tubules: transport water/ions/nutrient, so need surface area: cuboidal epithelium with apical membranes (inside tube) that have brush-border micovilli and basolateral membranes (outside) that have basal invaginations.
Thin loop of Henle: mostly just salt and water thru membrane: simple squamous epithelium.
What is the juxtaglomerular apparatus?
The junction of the distal convoluted tubule and the afferent and efferent arterioles. Location of Macula Densa cell detection/response to osmolar levels of Na+
Where are Macula Densa cells, and what is their function?
Cells in the convoluted distal tubule that that respond to osmolar levels of Na+ and in response, secrete substances onto the afferent tubule (mostly). Juxtaglomerular cells in/around afferent tubule respond with either changes in smooth muscle contraction or release of renin onto blood.
Why is renal blood flow maintained homeostatically between extremes?
(Receptors detect things when blood is moving at a faster pace) Needs to be high enough to ensure precise regulation of body fluid volumes and solute concentrations but slow enough to reabsorb indespensible constituents such as Na+
Describe the filtration barrier’s structure
- Capillary epithelium
- Basement membrane
- Slit diaphragms b/w podocyte foot processes
What is a podocyte?
Cells of the visceral layer of the Bowman’s capsule. Slit diaphragms connect foot processes, but permit the passage of molecules.
What are the 2 factors that determine whether a molecule passes through the filtration barrier?
- Size: fenestrations in capillary endothelium permit passage of plasma proteins; small apertures of basement membrane restrict passage of larger proteins; slit membranes of podocyte layer restrict remaining proteins.
- Charge: filtration sys. is made of negatively charged proteins, which repel proteins.
