Kidney 3 Flashcards
Components of the glomerulus
- glomerular filtration membrane
- podocytes of epithelium
Parts of the glomerular filtration membrane
- inner (porous)
- middle (selective permeability)
- outer
What does the outer glomerular filtration membrane contain?
Podocytes
Parts of podocytes
- pedicles
- filtration slits
Podocytes: pedicles
Projections that adhere to
- basement membrane
- other podocytes
Podocytes: filtration slits
- formed between pedicles
- covered with anions (negative charge) preventing protein filtration
glomerular filtrate =
- what passes through the 3 layers of the membrane
- forms primary urine
Bowman’s space =
Area between capillary layers and Bowman’s capsule
Afferent arteriole carries blood where?
Into the glomerulus
Efferent arteriole carries
Filtered blood away from the glomerulus
These cells release renin
Juxtaglomerular cells
Where are the juxtaglomerular cells located?
Within afferent and efferent arterioles
Macula densa =
- specialized cell that sits between afferent and efferent arteriole
- Na+ sensing cells of the distal tubule
PCT cell types
cuboidal cells with microvilli
Why do PCT cells have microvilli?
Enhances reabsorption
This is the primary end goal of the PCT
Active reabsorption of Na+
Loop of Henle descends into the
Medulla
Loop of Henle: Descending portion involved with
Passive transport of H2O into the medulla for reabsorption
Loop of Henle: descending portion function
- active transports of solutes for reabsorption
- approx 65% of solutes are reabsorbed here
function of the DCT
Continues reabsorption of other ions
Collecting duct connects
Nephron to ureter
These drain into one collecting duct
Many DCTs drain into the same duct. The urine then leaves the kidney from here into the ureter
This loop is highly permeable to water. Why?
- descending loop
- passive transport of water following the Na+
Ascending loop: permeability
- NOT permeable to water
- water can’t follow the NaCl transport
Transport of ions out of the ascending loop is (active/passive)
Active
This is the reason the medullary interstitium stays salty
Countercurrent exchange system
Hormones that affect the kidneys
- ADH
- Aldosterone
- Atrial natriuretic peptide
- Diuretics
ADH controls
water reuptake in distal tubules
Aldosterone function
- reabsorb sodium into vessels from distal tubules and collecting ducts
- secrete K+ from vessels
From where is aldosterone secreted?
Adrenal cortex (under regulation of RAAS)
ADH comes from
Posterior pituitary
What is atrial natriuretic peptide?
- diuretic
- decreases aldosterone
- dilates vessels
How does atrial natriuretic peptide act as a diuretic?
- inhibits renin
- renin inhibits Na+ and water reabsorption into vessels
How do diuretics enhance urine flow?
By decreasing reabsorption
Hormones synthesized or activated by kidneys
- urodilatin
- EPO
Urodilatin
- natriuretic peptide
- stimulated by increased BV and BP
EPO
stimulates RBC production due to decreased O2 delivery to kidneys
Atrial natriuretic peptide is released from _____
Heart
