KEY wk 9 lec 2 Flashcards
functional unit of the kidney that filters blood; modify filtrate and turn into urine
nephron
2 parts of nephron
- Glomerulus and
Bowman’s capsule - Uriniferous tubules
2 types of nephrons
cortical nephrons
juxtamedullary nephrons
cortical vs juxtamedullary nephrons
Cortical nephrons – LOH does not descend far into the medulla, no thin ascending LOH
Juxtamedullary nephrons – LOH descends deeply into the medulla, has a thin ascending LOH
function of glomerulus and bowmans capsule
special membrane to form ultra filtrate from blood –> ultrafiltrate into urine
role of proximal convoluted tubule
reabsorb solutes, water, nutrients
waste secretion
role of loop of henle
countercurrent exchangers and multipliers to concentrate filtrate
**concentrate urine
role of distal convoluted tubule and collectiling system
urine composition is finalized via hormones
principal cells: tweak K+, Na+ and water reabsorption/secretion
intercalated cells: pH homeostasis
role of principal and intercalated cells in the distal convulted tubule and collecting system
▪ Principal cells – important in final “tweaking” of K+, Na+ and water reabsorption/secretion
▪ Intercalated cells – important in pH homeostasis
SLIDE 11 chart
kidney primary role
remove substances from bloodstream
via clearance into urine
kidney/ renal clearance
volume of plasma from which a substance is completely removed by the kidneys per unit of time.
kidney’s ability to clear a substance from the bloodstream through urine formation.
removal of substance from blood is expressed in _____. lower blood [ ] means ____ rate of removal
substances from the blood (i.e. meds) is expressed in half-lives – the lower the blood concentration, the lower the rate of removal
3 ways kidney handles substances
- filtration (dissolved substances via starling forces and permeability into bowmans space)
- secretion (transport substances from blood into tubules)
- reasbosrption (transport substances from tubules back to blood)
where does filtration occur in the kidneys? how does it enter and exit? what structures allow for substance to enter?
glomerulus (special capillaries)
via afferent and efferent arteriole
The glomerular capillaries have fenestrations (small pores) that allow for the passage of water, ions, small molecules (such as glucose and amino acids), and waste products from the blood into the Bowman’s capsule, which surrounds the glomerulus.
how much blood is filtered by glomerulus? what cant fit through fenestrations so wont be filtered?
what is the amount of blood available for filtration called? how much of it goes into bowmans space and what is this called?
40%; RBC cant fit so hematocrit isn’t filtered
renal plasma flow
20% of RPF goes into bowmans space = glomerular filtration rate (120ml/min)
whats the GFR
120ml/min
estimated glomerular filtration rate (eGFR)
measure how good kidneys are at filtering waste from blood
the volume of fluid filtered from the kidney’s glomerular capillaries into the Bowman’s capsule per unit time.
what can pass and what cant pass through fenestrations in glomerular capillaries
- small molecules like water, ions, glucose, amino acids, and waste products to pass through
- while retaining larger molecules like proteins and blood cells within the bloodstream.
glomerular filtration barrier permeability based on
size and charge
can slight change surface area and permeability
which ions go through glomerular barrier ? which charge? what cant go through?
sodium (Na+), potassium (K+), chloride (Cl−), and calcium (Ca2+).
The basement membrane and slit diaphragms have a negative charge due to the presence of glycoproteins, which repel negatively charged molecules. This charge barrier helps prevent the filtration of negatively charged proteins, such as albumin, while allowing the passage of smaller ions and neutral molecules.
The glomerular basement membrane and the slit diaphragms are more permeable to
smaller, more positively- charged solutes
but if small, i.e Cl- can go through
starling forces
hydrostatic pressure driving water OUT of a capillary and oncotic pressure pulling water INTO a capillary