Chapter 19 Flashcards
Functions of the Kidney (6)
Regulation of extracellular fluid volume and blood pressure
Regulation of osmolarity
Maintenance of ion balance
Homeostatic regulation of pH
Excretion of wastes
Production of hormones
Kidney facts
99% of fluid that enters the kidneys returns to the blood
The kidneys filter 180 L of plasma each day. -
125 ml/min.
Therefore, the total plasma volume (~3 L) is filtered 60 times/day.
- Other capillary beds filter ~3 L/day.
Average volume of urine leaving the kidneys is 1.5 L/day.
Renal blood supply
20% of resting CO
Portal system of kidney
goes from - Afferent arteriole glomerulus efferent arteriole peritubular capillaries/vasa recta
Portal system of kidney
goes from - Afferent arteriole glomerulus efferent arteriole peritubular capillaries/vasa recta
layers of kidney
Cortical (80% of nephrons)
Justamedullary (20% of nephrons,(bottom of loop of henle))
layers of kidney
Cortical (80% of nephrons)
Justamedullary (20% of nephrons,(bottom of loop of henle))
Tubular Elements of the Kidney
Bowman’s capsule is the site of plasma filtration with the *glomerulus
- Together referred to as renal corpuscle
Proximal tubule
Loop of Henle – descending limb and ascending limb
Distal tubule
Collecting ducts – converge and drain into the renal pelvis
Distal nephron* – distal tubule and collecting ducts
Juxtaglomerular apparatus – ascending limb passes between afferent and efferent between arterioles at the glomerulus
Function of Proximal Nephron
Filtration
Reabsorbtion
Secretion
Function of Proximal Nephron
Filtration (Blood to lumen) (renal corpuscle - bowmens + glomerulus) (20% plasm is filtered in nephron, 99% return to blood later)
Reabsorbtion (Lumen to blood)
Secretion (blood to lumen)
Excretion (lumen to out of body)
Filtration barriers
Capillary Endothelium
Basal Lamina
Epithelium of Bowman’s Capsule
Urinary system id composed of…
two kidneys, two ureters, a bladder, and a urethra
Urinary system id composed of…
two kidneys, two ureters, a bladder, and a urethra
FIltration, reabsorbtion, secretion
Filtration -movement of fluid from plasma to Bowman’s capsule.
Reabsorption- movement of filtered materials from tubule to blood.
Secretion - movement of selected molecules from blood to tubule.
Nephron
Functional unit of kidney
Nephron
Functional unit of kidney
pressures effecting Glomerular filtration
Capillary blood pressure (+filtration)
Capillary colloid osmotic pressure (-fitration, pushes fluid back to plasma)
Capsule fluid pressure - Opposes filtration
Colloid Osmotic pressure + Hyrodrostatic pressure (bowmans) =
Hydrostatic pressure (glomerulus)
Does MAP effect GFR
A very minimal affect
GFR is controlled by
Renal arterioles
GFR is controlled by
Renal arterioles (most from afferent)
How doe GFR increase or decrease
Renal blood flow, mean arterial pressure, and the permeability of Bowman’s Capsule
GFR hormones
Angiotensin II = Vasoconstriction
How do hormones increase membrane permeability?
by changing the size of the filtration slits or contraction of the mesangial cells
How do hormones increase membrane permeability?
by changing the size of the filtration slits or contraction of the mesangial cells
glomerular filtration rate
amount of fluid that filters into Bowman’s capsule per unit time. Average GFR is 125 mL/min, or 180 L/day.
GFR autoregulation
Myogenic response (responds to pressure changes)
Tubuloglomerular feedback (local or paracrine control)
Hormones and autonomic neurons also influence GFR
Renin
secreted by granular cells, involved in salt and water balance
Modified portions of tubule eg
macula densa cells (causes afferent arteriole to contrict when fluid flows past, causing GFR to derease)
Paracrines in feedback loops…
ATP
Nitric oxide
adenosine
Reabsorbtion
location, type of transport
PCT (proximal tubules)
Active or passive transport
H2O follows Sodium
Na+ and SGLT protein
Pulls glucose against the concentration gradient
Na+ and SGLT protein
Pulls glucose against the concentration gradient
steps of reabsorbtion (4)
1) Na is reabsorbed (Active Transport)
2) Electrochemical gradient causes Anion reabsorbtion
3) H2O moving by osmosis, causing fluid volume in lume to decrease, and others increase
4) Permeable solutes (K+, Ca) are reabsorbed by diffusion.
steps of reabsorbtion (4)
1) Na is reabsorbed (Active Transport)
2) Electrochemical gradient causes Anion reabsorbtion
3) H2O moving by osmosis, causing fluid volume in lume to decrease, and others increase
4) Permeable solutes (K+, Ca) are reabsorbed by diffusion.
