Renal Physiology Lecture Powerpoint Flashcards
9/9/19
Kidney homeostatic functions (6)
- filters blood plasma eliminating waste, free radicals and drugs
- regulates blood volume and pressure
- regulates osmolarity of body fluids
- secretes renin
- secretes erythropoietin
- Activates vitamin D
Kidney shares this homeostatic function with the liver and this function with the lungs
Liver: Detoxification (obvi) but also gluconeogenesis (a small amount)
Lungs: regulates acid base balance
Renin definition
Major component of the RAAS which allows the kidneys to control the body’s BP by regulating fluid volume
Erythropoietin definition
Hormone released in response to low plasma o2, acts on hemocytoblasts to convert them into erythrocytes to increase the number in circulation
Vitamin D3 activation by the kidney
Kidney functions to convert vit D3 to active form vit D2
Where is the kidney in relationship to the peritoneum?
Retroperitoneal - behind the peritoneum
Urine flow pathway from collecting duct to exit
- Collecting duct
- Renal papilla
- Minor calyx
- Major calyx
- Renal pelvis
- ureter
- bladder
- urethra (prostatic, membranous, spongy in men, just urethra in women)
Renal pyramids and renal columns definition
Renal pyramids are the triangles pointed toward the center of the kidney that are composed of the renal medulla
Renal columns are the projections that fill the space between the renal pyramids
2 types of nephrons and their definition
1) cortical - short nephron loops that have a shorter loop of henle that dips into the outer medulla
2) Juxtamedullary - long nephron loops with longer glomeruli that dip into the deeper medulla and are extremely important in maintaining a salt gradient as well as conserving water
How many nephrons are there in a kidney?
Approx 1 million
Components of a renal corpuscle (2)
- Glomerulus
- Bowman’s capsule
The afferent arteriole entering the glomerulus typically has ___ hydrostatic pressure relative to the efferent and is thus vaso____
higher, vasodilated
Portions of the nephron from glomerulus to collecting duct
- Glomerulus
- proximal convoluted tubule
- Descending loop of henle
- ascending loop of henle
- distal convoluted tubule
- collecting duct
Glomerulus definition and function
A tuft of blood vessels from the afferent arteriole that allow for fluid filtration of the blood into the proximal convoluted tubule before the capillaries converge and exit as the efferent arteriole
Bowman’s capsule definition and function
Visceral and parietal epithelial cell layers surrounding and below a basement membrane of the glomerulus containing podocytes where fluid can pass onward into the proximal convoluted tubule from the glomerulus
Podocytes definition and function
Cytoplasmic extensions that wrap around capillaries of the glomerulus from bowman’s capsule, have openings called filtration slits that limit the substances that can be filtered through relaxation and contraction
Type of capillaries located in the glomerulus
Fenestrated
Filtration membrane of the glomerulus definition, and the 3 layers that make it up
Filtration membrane is the thickness between the endothelium of the capillary to the space of bowman’s capsule, the 3 layers are the 1)fenestrated endothelium, 2)basement membrane, and 3)filtration slits of the podocytes
Blood pathway through the kidney from renal artery to renal vein
- renal artery
- interlobar arteries traveling up columns of the kidney
- arcuate arteries that travel across pyramids of the kidney
- interlobular arteries that travel into the cortex
- afferent arterioles
- glomerulus
- efferent arterioles
- peritubular capillaries surround tubular portion of nephron capturing and reabsorbing substances
- interlobular vein
- arcuate veins
- interlobar veins
- renal vein
Juxtaglomerular apparatus definition and function
A specialized structure composed of macula densa, juxtaglomerular cells, and mesangial cells that functions to rregulate filtrate formation and systemic BP
Macula densa defnition and function
epithelial cells in the distal convoluted tubule adjacent to juxtaglomerular cells part of the juxtaglomerular aparatus. Senses changes in solute content of filtrate (decreased Na+) in lumen and secretes paracrine messenger to sitmulate JG cells
Juxtaglomerular cells definition and function
Modified smooth muscle cells that form a cuff around the afferent arteriole as it moves to the glomerulus part of the juxtaglomerular apparatus. Contains renin granules and are stimulated to release by acting as mechanoreceptors that directly sense BP in afferent arterioles
Mesangial cells definition and function
Cells between the afferent and efferent arterioles and among capillaries of the glomerulus part of the juxtaglomerular apparatus. Thought to mediate communication between juxtaglomerular cells and macula densa (i.e. macula densa at distal tubule sends paracrine signals thru messangial cells to reach JG cells to release renin)
Renal plexus definition and function
sympathetic division ANS nerves that follow the renal artery and function to regulate the rate of bloodflow thru the kidneys by regulating diameter of arterioles, can very quickly adjust blood flow
3 general processes in the formation of urine
1) glomerular filtration
2) tubular reabsorption into peritubular capillaries from nephron
3) tubular secretion from renal capillaries to nephron
Some drugs such as ___ and ____ are secreted via tubular secretion
NSAIDS, cephalosporins
Glomerular filtrate is similar to ___ in content
Plasma
How much renal filtrate is reabsorbed into the blood stream?
As much as 99%
Net filtration pressure is formed from these three components
- Blood hydrostatic pressure going into the proximal convoluted tubule (largest, variable)
- Colloid osmotic pressure pulling fluid into the efferent arteriole
- Capsular pressure pulling fluid into the efferent arteriole
Glomerular filtration rate definition (GFR)
Amount of filtrate formed by kidneys in 1 minute
Typical GFR for adults
100-125mL/min
In a 24 hr period blood passes thru the kidneys at least ___ times
36