Module 2 Flashcards
(68 cards)
Components of the renal system
two kidneys, two ureters, the urinary bladder, and the urethra.
the functional unit of the kidney
nephron
Key functions of the renal system
1
Maintain blood volume and osmolality of ECF
2
Regulate amounts of ions (such as sodium, potassium, bicarbonate, and hydrogen) in the body
3
Help to regulate pH (acid-base balance) of body fluids
4
Regulate hormone concentrations by eliminating them
5
Produce hormones (calcitriol and erythropoietin)
6
Produce renin, an enzyme important for formation of angiotensin (a potent vasoconstrictor)
7
Excrete foreign substances such as drugs, pesticides, and other ingested chemicals
What comprises the kidney
the nephron is comprised of a glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct
2 ways the glomerulus acts as a filter
interlocking cells called podocytes form small slits and fenestrations screening out cellular components and large plasma proteins, and a negatively charged layer repels anionic molecules
3 intrinsic mechanisms of the kidney that help maintain GFR.
juxtaglomerular cells respond to decreased renal perfusion pressure by releasing renin;
the myogenic reflex monitored by mesangial cells responds to arteriolar wall tension through glomerular arteriole vasodilation or vasoconstriction;
and the macula densa responds to flow and concentration alterations of the tubular filtrate by increasing or decreasing afferent and efferent resistance
How does the kidney stimulate RBC production
in response to low oxygen in tissues, the kidneys release erythropoietin, which stimulates the bone marrow to produce RBC’s
what are the two types of nephrons
Cortical nephrons and juxtamedullary nephrons
Cortical nephrons
A nephron with a loop of Henle that only penetrates the outer medulla, which is closest to the cortex. It contains a short loop because it does not extend deep into the kidney.
Juxtamedullary nephrons
A nephron with a loop of Henle that penetrates the inner medulla, which is closest to the renal pelvis. It contains a long loop because it extends deep into the kidney.
The majority of mammal species possess both types of nephrons. However, the percentage of each varies across species. For example, a pig has more cortical nephrons (97%), while a cat has almost 100% juxtamedullary nephrons.
what is the glomerulus
A tuft of capillaries interposed in the course of two atrioles
what is the glomerulus inside of
Bowmans capsule
What does the glomerulus do
functions like a sieve; it filters out the smaller components like water, electrolytes, etc., and retains larger components like red blood cells and high molecular weight proteins.
Anything bound to a protein, like hormones, is not filtered
Bowmans space
the space between the glomerulus and the capsule
how does blood leave the glomerulus
through the efferent arteriole
glomerular filtration rate (GFR)
The rate at which filtration is performed
used to assess the functions of the kidney
How does glomerular filtration function
with the permeability of three layers within the glomerular membrane
what are the three layers of the glomerular membrane
Endothelial cells that line the inside of the capillaries (the glomerulus). The capillaries are very permeable because in between these cells there are gaps, called fenestrae (small holes), that allow certain sized molecules to leak out.
Basement membrane of the capillaries. This wall is comprised mostly of permeable connective tissue like collagen and has large spaces through which the filtrate can pass. It also has a negative charge that helps the basement membrane to repel anything that also carries a negative charge, such as plasma proteins.
layer of specialized epithelial cells called podocytes. Each cell has finger-like projections that form slit pores which allow the final filtrate to pass into Bowman’s space.
what size substance cant permeate the glomerular membrane
ill not allow substances that are 4 nm or greater to pass (albumin or any protein larger than cannot pass). Substances that are 2 nm or smaller are freely filtered into Bowman’s space.
what two factors determine a molecules permeability in the glomerular membrane?
Size and charge
What forces cause fluid to filter through the glomerular membrane?
blood pressure (hydrostatic pressure) inside the glomerular capillaries.
The colloidal osmotic pressure (COP), also called oncotic pressure, is the pressure exerted by plasma proteins (mainly albumin) that opposes filtration
Pressure in Bowman’s capsule opposes filtration
what is the equation for net filtration pressure
Net filtration pressure = Pressures favoring filtration - Pressures opposing filtration
Net filtration pressure, mmHg = (PG) - (PB + G)
PG = Hydrostatic pressure inside glomerular capillaries promotes filtration.
PB = Pressure inside Bowman’s capsule opposes filtration.
G = Colloidal (Onctotic) osmotic pressure of glomerular plasma proteins (COP), opposes filtration.
B = Colloidal osmotic pressure of Bowman’s capsule proteins promotes filtration. Under normal physiological conditions, B = 0.
Since under normal physiological conditions Colloidal osmotic pressure of Bowman’s capsule proteins (B) that promotes filtration is = 0
what is one of the best methods for assessing kidney function
measuring GFR (mL/min)
What substances are reabsorbed from filtrate in the nephron
water, glucose, amino acids, and electrolytes
