the nephron Flashcards
what are the two types of nephron?
cortical and juxtamedullary nephrons
which nephron has the long loop of henle (extends into the medulla) ?
juxtamedullary
what is the function of both nephron types?
urine production
what are the two main parts to a nephron?
the renal corpuscle and renal tubules
what is the renal corpuscle consist of?
the glomerulus and the bowman’s capsule
what are the two types of tubules a nephron has?
proximal and distal tubules
what is the main function of the proximal tubule?
most reabsorption of nutrients and filtrates
what is the main function of the distal tubule?
reabsorption of water and ions
what role does the loop of Henle have?
major role in maintaining osmotic pressure
what is the glomerulus?
a bundle of tightly packed capillaries resulting in high pressure which helps in plasma filtration
what are the two layers of the Bowman’s capsule?
parietal (outer) and visceral (inner)
what is the structure of a glomerular capillary?
endothelium forms fenestrae, has a glomerular basement membrane and visceral epithelial cells called podocytes, these form the filtration slit diaphragm
what filters out of the slit pores?
protein-free plasma
what is the structure of the proximal (convoluted) tubule?
wall of cuboidal epithelial cells which are covered in microvilli- these make up the brush border (this is why most reabsorption of nutrients occurs in the PCT). the cuboidal cells are also rich in mitochondria. the cells have tight (leaky) junctions which allow transport between cells
what are the two limbs of the loop of Henle called?
the descending and ascending limbs
what is the structure of the descending limb?
cuboidal epithelial cells
what is the structure of the thin acsending and descending limb?
lined by simple squamous epithelial cells
what is the strcuture of the thick ascending limb?
simple cuboidal epithelial cells
what is the structure of the distal convoluted tube?
simple cuboidal epithelium, no brush border, lots of mitochondria but less than PCT, also has tight junctions.
what is the collecting ducts function and structure?
its function is to collect urine and transport it to the bladder. they are made from simple cuboidal epithelial cells, they merge and increase in size as they go down the medulla.
where is the juxtamedullary apparatus located and what is its function?
it is located just outside Bowman’s capsule, it regulates blood pressure and filtration rate of the glomerulus.
what are the two types of specialised cells that make up the juxtamedullary apparatus?
macula densa and granular cells
what is the structure and function of macula densa cells?
they are densely packed cuboidal epithelial cells, located in the distal convoluted tube. their role is to detect and regulate sodium ion concentration
what is the structure and function of granular cells?
they are smooth muscle cells that line the afferent arterioles, they regulate blood pressure in the arteriole by contracting/relaxing. granular cells secrete renin which regulates blood pressure via the renin-angiotensin-aldosterone system (RAAS)
