00:00 / 00:00
Acid-base map and compensatory mechanisms
Buffering and Henderson-Hasselbalch equation
Physiologic pH and buffers
The role of the kidney in acid-base balance
Plasma anion gap
Renal system anatomy and physiology
Body fluid compartments
Movement of water between body compartments
Measuring renal plasma flow and renal blood flow
Regulation of renal blood flow
TF/Px ratio and TF/Pinulin
Phosphate, calcium and magnesium homeostasis
Free water clearance
Kidney countercurrent multiplication
Distal convoluted tubule
Loop of Henle
Proximal convoluted tubule
Tubular reabsorption and secretion
Tubular reabsorption and secretion of weak acids and bases
Tubular reabsorption of glucose
Tubular secretion of PAH
0 / 8 complete
0 / 1 complete
glomerular filtration barrier p. 601
glomerular filtration rate and p. 602
glomerular filtration barrier and p. 601
ACE inhibitor effects p. NaN
ANP effect on p. 610
glomerular dynamics in p. 603
juxtaglomerular apparatus p. 609
prerenal azotemia p. 622
glomerular filtration barrier and p. 600
The workhorses of the urinary system are the kidneys which are the twin, bean-shaped organs in your body that clear harmful substances by filtering blood - like a water purification plant that helps clean the drinking water for a city.
Blood filtration happens inside the over a million nephrons scattered inside each kidney, and each nephron is made up of a renal corpuscle and a renal tubule.
So let’s zoom in on the renal corpuscle, which is where blood filtration starts.
The renal corpuscle is made up of the glomerulus - a tiny bed of capillaries - and the Bowman’s capsule surrounding the glomerulus.
Between the glomerulus and Bowman’s capsule there’s a space called Bowman’s space.
Blood gets to the glomerulus through the afferent arteriole, but interestingly enough, once the blood leaves the glomerulus, it doesn’t enter into venules.
Instead the glomerulus funnels blood into efferent arterioles which divide into capillaries a second time.
These capillaries are called peritubular capillaries - because they are arranged around the renal tubule.
Now, the first step in blood filtration happens at the glomerular filtration barrier.
The glomerular filtration barrier is made up of three layers and together they separate the blood inside the glomerular capillaries from the fluid inside Bowman’s capsule.
They work like a sieve, allowing water and some solutes in the plasma like sodium, to pass into Bowman’s space, while keeping red blood cells and plasma proteins in the blood.
Starting from the capillary lumen, the first layer of the glomerular filtration barrier is the endothelium, made up of glomerular capillary endothelial cells.
These cells have fenestrations, which are like pores in the cell themselves, tiny spots where the cytoplasm isn’t filled in so that solutes and proteins can pass right through. But the fenestration are tiny so they block red blood cells from passing through.
Blood minus red blood cells is plasma - so plasma gets to the second layer of the glomerular filtration barrier, which is the basement membrane.
Glomerular filtration is a process by which blood plasma is filtered through the glomerular filtration membrane. This is the first step of urine formation, by which the kidney starts to eliminate toxins from blood plasma. The glomerular filtration membrane has tiny pores allowing only small elements to pass, and ideally spare large molecules such as albumin and blood cells.
Latest on COVID-19
Nurse Practitioner (NP)
Physician Assistant (PA)
Create custom content
Raise the Line Podcast
Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
Terms and Conditions
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.