Kidney Structure and Function Flashcards
What are the functions of the kidneys?
Balance of water, salt and acid-base balance
Maintenance of plasma volume and osmolarity
Excretion of metabolic waste products and foreign compounds
Secretion of renin and erythropoietin
Conversion of vitamin D to calcitriol
What are the functions of the substances produced by the kidneys?
Renin = controls arterial blood pressure Erythropoietin = role in red blood cell production Calcitriol = absorbs calcium in the GI tract
What is the primary function of the kidneys?
To regulate the volume, composition and osmolarity of body fluids
What is the waste product produced by the kidneys?
Urine
What is the functional unit of the kidney?
Nephron = carries out filtration, reabsorption and secretion
What are the two types of nephron?
Juxtamedullary (20%) and cortical (80%)
What is urine?
Modified filtrate of blood
What are some features of the kidney that show its specialisation for its function?
Kidney incorporates filtration system, rich blood supply and mechanism for urine production
What are the renal processes involved in producing urine?
Glomerular filtration, tubular reabsorption and tubular secretion
How much of the plasma that enters the glomerulus is filtered?
20% = remaining 80% leaves through the efferent arteriole
How is the renal tubule like a conveyor belt?
Substances are added or removed as the urinary filtrate moves from the proximal to distal end
What are filtration and secretion equal to?
Reabsorption and excretion (for any substance, filtration + secretion = reabsorption + excretion)
How can the rate of excretion be calculated?
Rate of filtration + rate of secretion - rate of reabsorption
How is the movement of substances within the kidneys described?
In terms of concentration x flow
What is the rate of filtration?
Mass of a substance filtered into the Bowman’s capsule per unit time
How can rate of filtration be calculated?
Plasma concentration of substance x glomerular filtration rate
How can the rate of excretion be calculated using urine values?
Urine concentration of substance x urine production rate
How can the rate of reabsorption be calculated?
Rate of filtration x rate of excretion
What has happened if rate of filtration is greater than rate of excretion?
Net reabsorption of that substance has occurred
How can rate of secretion be calculated?
Rate of excretion - rate of filtration
What has happened if rate of filtration is less than rate of excretion?
Net secretion of that substance has occurred
Are rate of filtration and rate of excretion easy to measure?
Yes
What do rate of reabsorption and secretion reflect?
Tubular modification of filtrate = obtained as the difference between filtration and excretion
