The kidneys structure and function Flashcards
List some functions of the kidney
Water balance Salt balance Plasma volume Plasma osmolarity Excretion of endogenous waste products Excretion of exogenous waste products Acid-base balance Long term regulation of blood pressure Red blood cell production Activation of vitamin D
Urea, bilirubin and uric acid are breakdown products of what respectively?
Urea - protein
Bilirubin - haemoglobin
Uric acid - purines
Erythropoetin is released in response to what? How does it manage this?
Hypoxia
Stimulation of red blood cell production
What effect does calcitriol have on the GI tract?
Stimulates calcium absorption
Vitamin D undergoes metabolism by two organs, name these
Liver
Kidney
What is the kidneys primary function?
To regulate the volume, composition and osmolarity of the extracellular fluid
What is the balance concept of homeostasis?
Input must match output
List all components of the renal system
Kidneys
Ureters
Bladder
Urethra
Describe the macrostructure of the kidney
Renal capsule Renal cortex Renal medulla Medullary pyramids Renal columns Minor calyx Major calyx Renal pelvis Renal hilum (artery, vein, ureter)
What is the functional unit of the kidney?
Nephron
What three processes does the nephron carry out?
Glomerular filtration
Tubular reabsorption
Tubular secretion
What are the two types of kidney nephron and which is the most numerous?
Juxtamedullary
Cortical (most common)
Describe the changes in vasculature over the course of the nephron
Renal artery > Afferent arteriole > Glomerulus > Efferent arteriole > Peritubular capillaries > Venule > Renal vein
The collecting duct receives urinary filtrate from many different nephrons. T/F
True
How do the descending and ascending limbs of the loop of henle differ in diameter?
Descending limb - thin
Ascending limb - thick
When is the tubular fluid termed urine? Why?
After it leaves the collecting ducts
It is no longer modified after leaving the collecting ducts
Describe the differences between the two nephron types
Juxtaglomerullary - long loop of Henle, vasa recta
Cortical - short loop of Henle, peritubular capillaries
What is the role of juxtaglomerullary nephrons?
Producing concentrated urine
The diameter of the efferent arteriole leaving the glomerulus is larger than that of the afferent arteriole. T/F
False - the diameter of the afferent arteriole is larger
What forms filtration slits?
Podocytes
What are the cells of the juxtaglomerular apparatus? What are their respective functions
Macula densa - senses ionic concentration of filtrate
Lacis cells - unknown
Granular/juxtaglomerular cells - secretes renin
What is urine?
Modified filtrate of the blood
Around which fraction of the total cardiac output do the kidney receive?
1/4 (i.e they have a rich blood supply)
What two components of plasma should the urinary filtrate not contain?
RBC
Large proteins
Write the equation for calculating rate of filtration (for a freely filterable substance)
Rate of filtration = plasma concentration x GFR
What is the average GFR of a healthy adult?
125ml/min
What effect should increased plasma concentration have on GFR?
Increase
and vice versa
Write the equation for calculating rate of excretion
Rate of excretion = urine concentration x urine flow rate
The rate of excretion changes dramatically depending on hydration status. T/F
True
How do we know a substance has been reabsorbed? Write the equation for calculating rate of reabsorption
Rate of filtration > rate of excretion
Rate of reabsorption = rate of filtration - rate of excretion
How do we know when a substance has been secreted? Write the equation for calculating rate of secretion
Rate of excretion > rate of filtration
Rate of secretion = rate of excretion - rate of filtration
The rates of reabsorption and secretion reflect tubular modification. T/F
True
What is important to convert when preforming these calculations?
The units (must always be litres per minute)
