Kidney 1 Flashcards
(30 cards)
What is the main function of the kidneys?
To removes organic, potentially toxic, waste products of cellular metabolism from the body. Especially nitrogenous waste in the form of urea/uric acid and creatinine
What are 5 other functions of the kidney?
- Regulates blood volume and hence blood pressure
- Controls ionic composition of plasma (Na+, K+, Cl-, Ca2+)
- Helps maintain optimal blood pH (H+, HCO3-)
- Reabsorbs useful nutrients that might otherwise be excreted
- Can also, during periods of extreme starvation, assist in breakdown of protein to provide fuel for other cells of the body
What 4 organs are part of the urinary system?
- Kidney
- Ureter
- Urinary bladder
- Urethra
What percentage of cardiac output do the kidneys receive?
20-25%
How many litres of blood flows through the kidneys each minute?
1.2L
What does each nephron consist of?
Each nephron consists of a renal corpuscle and a renal tubule
What is the renal corpuscle composed of?
Bowman’s capsule and the glomerulus
What is the renal tubule composed of?
- Proximal convoluted tubule (PCT)
- Loop of Henle
- Distal convoluted tubule (DCT)
What are the 4 functions of a nephron?
- Production of filtrate
- Reabsorption of organic
nutrients - Reabsorption of water and ions
- Secretion of waste products into tubular fluid
What percentage of all nephrons are cortical nephrons?
85%
Where are the cortical nephrons located?
In the cortex
Where are the juxtamedullary nephrons located?
Nearer the renal medulla
What do the Loops of Henle extend into?
Deep into the renal pyramids
What are the 3 basic processes of urine formation?
- Filtration
- Reabsorption
- Secretion
Which arteriole is wider, the afferent or the efferent?
Afferent arteriole
How does glomerular filtration occur?
Occurs as fluids move across the glomerulus in response to glomerular hydrostatic pressure
What is glomerular hydrostatic pressure?
Blood pressure in the glomerular capillaries
What is nitrate composed of?
The filtrate is composed of water and small solutes able to pass through the filtration slits (e.g. sodium, potassium, chloride, glucose)
What is the rate of filtration per minute?
125 ml/min (180 litres each day)
How many litres of blood is in you body?
5L
How many times a day does your blood get filtered?
Approximately 35 times
How do you calculate the GFR (Glomerular filtration rate)?
GFR = UV/P U = Urine solute conc. V = Volume of urine excreted per minute P = Plasma solute conc.
What 4 things does a substance have to be before the GFR can be calculated?
- Filtered freely
- Not secreted or reabsorbed
- Not toxic
- Not metabolised/broken down
What is GFR?
Amount of filtrate produced in the kidneys per minute
