the kidney Flashcards
2.72
where are the kidneys located?
at the back of the abdomens
what are the kidney’s two important functions?
- regulate the water content in the blood
- they excrete the toxic waste products of metabolism
why is regulating the water content of the blood important for the kidneys?
vital for maintaining blood pressure
what is an example of a toxic waste product of metabolism?
urea
what substances are in excess of requirement?
salts
what are the 3 sections of the kidney?
- cortex
- medulla
- pelvis
where is the cortex located?
around the outside and has a lighter colour
where is the medulla located?
in the middle- triangular shaped
where is the pelvis located?
in the centre- yellowy colour
what do nephrons do?
they filter the blood
what are nephrons?
tiny structures that filter the blood
what are nephrons also known as?
kidney tubules/ renal tubules
where do the contents of the nephron drain into?
the renal pelvis
where does the urine collect?
in the renal pelvis
where does urine flow down into?
the ureter
where is urine stored?
in the bladder
what is the nephron made up of?
a kidney tubule which has several sections
what are the sections that make up the nephron?
- bowman’s capsule
- proximal convoluted tube
- loop of Henle
- distal convoluted tube
- collecting duct
what is the glomerulus?
a network of capillaries with a knotted section that sits inside the Bowman’s capsule
where is the efferent arteriole?
at the exit of the glomerulus
where is the afferent arteriole?
at the entrance of the glomerulus
which arteriole has the larger diameter- the efferent or afferent?
the efferent arteriole- smaller
the afferent arteriole- larger
what does the difference in sizes in the arterioles do?
creates a build up pressure in the capillaries
what does the pressure in the glomerulus do?
- forces small molecules such as urea, glucose, amino, acids and salts out of the capillaries of the glomerulus and into the Bowman’s capsule
- this forms the glomerular filtrate
what are some examples of small molecules?
urea, glucose, amino acids and salts
what are some examples of larger molecules?
proteins or red blood cells
what happens to the large molecules?
they stay in the blood as they are too big to fit across the capillary walls
what do the capillaries of the glomerulus have between the cells?
gaps
what does the basement membrane do?
controls which molecules can pass into the Bowman’s Capsule
how are the cells lining the PCT specialised for movement of molecules?
- have a folded membrane- increase surface area
- many mitochondria- provides ATP for active transport
where does the glomerular filtrate travel to?
the PCT
what happens to the useful materials in the glomerular filtrate?
- the specialised cells in the walls of the PCT move the useful materials back into the bloodstream
- initially, molecules will move by diffusion but some substances will undergo active transport
what is all reabsorbed?
- all of the glucose and amino acids
- some salts
- 80% of the water
what is involved in reabsorbing water?
the Loop of Henle and collecting duct
what does the Loop of Henle do?
- concentrates the urine by transporting salt into the blood by active transport
- this causes water to diffuse into the blood by osmosis
the blood being filtered and key substances being absorbed back into the blood is carried out in what order?
1) ultrafiltration
2) selective reabsorption of glucose
3) reabsorption of water and salts
where is water reabsorbed at?
loop of henle & collecting duct
where are salts reabsorbed?
loop of henle
where is glucose reabsorbed?
PCT
where is urea reabsorbed?
it’s not reabsorbed
what will your urine be like if you have lost a lot of water through sweating or dehydration?
- concentration
- lower volume of water
- darker, browner colour
what hormone does the collecting duct respond to?
ADH
what does ADH do to the collecting duct?
makes it more or less permeable- varies how much water is reabsorbed
why can the reabsorption of glucose not take place anywhere else in the nephron?
the gates that facilitate the active transport of glucose are only found in the PCT
do people with diabetes have low or high blood pressures?
high blood glucose levels as they cannot control them
high blood glucose levels means what for the glucose?
- not all the glucose filtered out can be reabsorbed into the PCT
- there is nowhere else for the glucose to be reabsorbed into- it ends up in the urine
