Physiology 2 Flashcards
the 10 functions of the kidneys
- water balance
- salt balance
- Maintenance of plasma volume
- Maintenance of plasma osmolarity
- Acid-base balance
- Excretion of metabolic waste products
- Excretion of exogenous foreign compounds
- secretion of renting to maintain arterial blood pressure
- secretion fo erythropoietin which is required to produce red blood cells
- Conversion fo 25- hydroxyvitamin D3 (cholecalciferol) to 1,25-hydroxyvitamin D3 (CALCITRIOL)
primary function of the kidney
is to regulate the volume, composition and osmolarity of body fluids
concept of homeostasis for any substance
input has to equal output which can be applied to Na+, K+, Ca2+, Cl- and PO42- so the kidney controls the excretion of these substances in order to maintain homeostasis
blood enters the kidney
via the renal artery
blood drains from the kidney
via the renal vein
what is the functional unit of the kidney
the nephron
the first part of the nephron is
the glomerulus
the glomerulus receives
branches of the renal artery called the afferent arteriole and exiting the glomerulus is the efferent arteriole
the glomerulus function is
filtration of the blood, blood flows through the glomerulus and small molecules bass into bowmans space where it is known as the filtrate
how does the filtrate get from the afferent arteriole into bowmans space
- the afferent arteriole is lined with endothelial cells which contains fenestrations which allows small molecules to pass through but prevents larger proteins passing through
- underneath the endothelial cells is the basement membrane which is negatively charge and repels larger proteins such as albumin inhibiting them from passing through
- on the inner layer of bowmans capsule there is a type of epithelial cell called podocytes which extend there foot processes onto the endothelial cells which ensures they tightly adhere to one another
increasing the diameter of the afferent arteriole
more blood can pass through the glomerulus and the glomerular filtration rate increases
reducing the diameter of the afferent arteriole
less blood can pass through the glomerulus and the glomerular filtration rate falls
after blood has been filtrated in the glomerulus
it flows through the proximal convoluted tubule
the proximal convoluted tubule is very important for
the re-abdsorption of ions like sodium, chloride, amino acids and glucose and it also re-abdorbs water
after the proximal convoluted tubule the filtrate passes into
the descending loop of henle and then into the ascending loop of henle
descending limb of the loop of henle is
impermeable to ions and ONLY re-absorbs water
ascending limb of the loop of henle is
impermeable to water and ONLY re-absorbs ions
the process occurring in the loop of henle is known as
counter-currant multipiclation
why is it called counter-currant
because the loop of henley are travelling in opposite directions
why is it called multipiclation
because the process of re-absorption of ions in the ascending loop of henle is active and by making the renal medially more acidic, it allows the passive movement of water from the descending limb into the intersitium which is a completely passive process
fluid then flows from
the ascending loop of henle into the distal convoluted tubule
the distal convoluted tubule re-absorbs
sodium and chloride
where the distal convoluted tubule passes the glomerulus
this is called the jucto-glomerual apparatus
the junta-glomerular apparatus
is the part of the kidney which controls blood pressure
