3) Urinary System Structure And Function Flashcards
What is are 2 examples of important roles of the kidney?
Remove urea from the blood (structures in the cortex)
Aid osmoregulation (tubules extending into the medulla)
What is involved in the urinary system? (8)
Aorta
Vena Cava
Renal Vein + Artery
Right + Left Kidney
Ureter
Bladder
Urethra
Sphincter Muscle
What is the function of the renal vein?
The renal vein takes cleaned blood from the kidney to the heart
What is the function of the renal artery?
The renal artery brings blood with wastes (urea) to the kidney to be cleaned
What gives kidneys its distinctive layers?
Due to 1-2million nephrons in each kidney
Where are the 2 kidneys located?
The 2 kidneys sit either side of the aorta at the rear of the abdomen
Where is blood filtered?
In the cortex
What is the purpose of the ureter?
Carry urine to the bladder
What is the functional unit of the kidney?
The nephron
What is the purpose of the Bowman’s capsule?
Has little resistance to fluid leaving the blood but prevents cells and large proteins from passing into the tubule
How is the proximal tubule adapted for rapid absorption?
The wall of the proximal tubule has a large surface area due to microvilli.
ATP readily available from many mitochondria.
How much fluid does the kidney filter out of the blood each day?
Around 180dm³ of fluid
Where does the majority of filtered fluid return to and how?
The blood, by a complex network of blood vessels around the kidney tubules.
What is ultrafiltration?
The process in which kidneys remove urea from the bloodstream
What is the first stage of produce urine?
Filtering of blood in the Bowman’s capsule
What is filtration based off of?
Particle size, most proteins are too big to pass into the tubules
What does the filtrate produced compare to?
The filtrate produced has a composition very similar to plasma
Why is there a very thin barrier between blood in the capillary and the tubule lumen?
Due to many gaps between the capillary endothelium cells
Why is the formation of filtrate promoted?
Because blood enters the glomerulus under pressure
The afferent arteriole entering the glomerulus is wider than the efferent vessel leaving.
How is majority of filtrate is returned to the blood?
Through the proximal convoluted tube (PCT)
What is left in high concentration in the filtrate?
Waste products such as urea.
What does 5 things do active transport recover in the blood?
Glucose, amino acids, proteins, vitamins and hormones.
How is active transport of the blood supplied?
By ATP produced by mitochondria
What does DCT stand for?
Distal convoluted tube
What are the 3 functions of the DCT?
-Secretes waste chemicals such as creatinine into the filtrate
-Pumps ions to control blood pH
-Helps control blood volume and therefore concentration of urine
What is the purpose of the loop of Henle?
Producing a very high concentration of solutes in the medulla of the kidney so it has a very low water potential.
How does low water potential affect urine?
Allows to produce urine more concentrated and less concentrated than plasma
What is hypertonic?
More concentrated
What is hypotonic?
Less concentrated
Explain how filtrate in the loop of Henle is hypertonic to blood plasma in some places
Filtrate is hypertonic at the base of the loop, deepest into the medulla. This is because water has left the filtrate by osmosis as it passes through the medulla, filtrate is isotonic to the medulla tissue.
Explain how filtrate in the loop of Henle is hypotonic to blood plasma in some places
Filtrate becomes hypotonic as it reaches the DCT as ions diffuse and are actively pumped out of the tubule as it passes out of the medulla.
The loop of Henle is a counter current multiplier, what does this mean?
This means that the flow of filtrate in the two limbs is in opposite directions and the longer the loop the greater the effect on the concentration of the filtrate.
Refer to PG.99 for diagram of loop of Henle
What is urine often tested for?
Proteins or glucose