Renal Function- Filtration Flashcards
Principal functions of the kidney
—Regulate volume/composition of ECF (will affect ICF) – Osmoregulation, Blood pressure and volume
—Regulate concentrations of ions in ECF
—Excretion – endogenous waste/metabolites, toxins, drugs Acid base balance
What do kidneys produce?
Renin
Erythropoietin
Calcitriol
Glucose
Urine
Function of produced renin
counteracts reduction in ECF volume and BP (blood pressure)
Function of produced erythropoietin
formation and maturation of RBCs
Function of produced calcitriol
Calcium homeostasis
Function of produced glucose
protect blood sugar during starvation
Kidney is a homeostatic organ, and control is achieved via…
cooperative functionality with circulatory & respiratory systems
These structures found within cortex or medulla?
-glomerulus
-bowman’s capsule
-proximal convoluted tubule
-cortical nephron’s LOH (loop of Henle)
-juxtamedullary nephron’s LOH
- Cortex
- Cortex
- Cortex
- Barely enters medulla
- Deep in medulla
Why is position of nephron in kidney important?
Nephron regulate water balance so their position matters
Three fundamental processes/functions within the nephron
- Filtration
- Reabsorption
- Secretion
What are the 2 types of differentiated cell types found along the length of the nephron due to differing functions
Principal cells
Intercalated cells
Principal cells reabsorb and secret what?
Intercalated cells reabsorb and transfer what?
Principal cells – reabsorb Na+, Cl- and secrete K+
Intercalated cells – reabsorb K+ and transfer H+
What structure in nephron does filtration occur in?
Glomerulus
Filtration in the glomerulus occurs as a result of…
Pressure differences within the system
Describe what occurs during filtration in glomerulus
-Blood enters afferent arteriole under relatively high pressure (high pressure due to actions of heart and resistance of efferent arteriole)
-high pressure results in extrusion of large amounts of water, plus glucose, proteins and other waste products
-overall around 20% of plasma is leaving in glomerulus and entering filtrate
-large molecules such as blood cells, large proteins are retained within bloodstream
What is a way to get rid of retained large waste molecules that were unable to be filtered?
Occurs where?
Secretion- taking waste products from blood stream and passing to filtrate
Occurs within PCT
Secretion of large molecules in the nephron can result in what?
What is a way to stop this from occurring? Where does this process occur?
Loss of solutes/water that we do not want to lose
Reabsorption- recovery of required components from filtrate (partial/total depending on what body needs)
-occurs in PCT, LOH, DCT, Collecting duct (whole rest of nephron)
Certain diseases will results in problems in filtration process. What do they cause which can result in what?
Cause more proteins to be passed out into urine/filtrate and are unable to be reabsorbed
Results in:
Proteinuria
Albuminuria
Haemoglobinuria
Rate of filtration is determined by…
hydrostatic and osmotic forces
What are the three main forces of water movement and what each causes
Which is the 4th that has no effect on movement of water
- Glomerular hydrostatic pressure—> very high pressure caused by actions of heart and differences in resistance of arterioles
- Hydrostatic pressure of Bowman’s Space—> as water builds in bowman’s space (space between glomerulus and bowmans capsule) it is pushed back into capillaries
- Oncotic pressure- pressure brought about by plasma proteins; holds water within capillaries as they are impermeable
- Osmotic pressure due to fluid in Bowman’s space- effectively 0 as filtrate is pulling away all those proteins; they aren’t staying in one space
How would you calculate the net ultrafiltration pressure?
Puf= Pgc - (Pbs + Tgc)
Puf= glomerular capillary hydrostatic pressure - (Hydrostatic pressure of bowman’s space + Oncotic pressure)
Calculation for Glomerular Filtration Rate (GFR)
GFR= Puf x (permeability of the filter, surface area (of filtration barrier))
Since we can change the net ultrafiltration rate of we change any of the values in the equation, this means we can regulate the…
GFR
Why should GFR be regulated?
GFR is regulated by what?
-so as to maintain stable ECF (and ICF)
-Principally regulated by changes in blood flow, protein osmotic pressures and hydrostatic pressure