Kidneys Flashcards
Which artery supplies the kidneys
Renal Artery
What is osmoregulation
homeostatic control of blood water potential
What is the filtering unit of the kidney?
the Nephron
Which area of the brain is responsible for osmoregulation
Hypothalamus
Which hormone acts on the collecting duct
Antidiuretic Hormone (ADH)
Where is ADH released from
Posterior Pituitary gland
What does ADH do in the kidney
- acts on the collecting duct and distal convoluted tubules
- makes them more permeable to water
- makes urine more concentrated
Describe the process of osmoregulation in a dehydrated person
- blood water potential decreases
- osmoreceptors in hypothalamus detect low water potential in the blood
- more ADH secreted by posterior pituitary gland
- DCT and CD made more permeable to water
- more water reabsorbed from collecting duct
- more concentrated urine
What are the sections of the kidneys
- Capsule
- Cortex
- Medulla
- Pelvis
Describe the process of selective reabsorption of Na+ from the lumen of the proximal convoluted tubule to the blood
- Na+ brought into the cells of the PCT down its concentration gradient through co transport with glucose and Cl- (from a high concentration in the lumen of the PCT to a low concentration of the cells of the PCT) PASSIVE
- glucose moves into the blood down its concentration gradient (facilitated diffusion- PASSIVE)
- Na+ actively transported out of cell into blood through Na+ K+ pump ACTIVE
Why would the length of Loop of Henle change between species?
species living in hot climate need to conserve more water thus have a longer Loop of Henle
What takes the waste product from the kidneys to the bladder
Ureter
Name the different sections of the nephron
- Glomerulus (inside the Bowman’s Capsule)
- proximal convoluted tubule
- Loop of Henle
- distal convoluted tubule
- collecting duct
How do the kidneys maintain a higher blood pressure than the rest of the body
afferent arterioles are wider then efferent
What processes do the kidneys do?
- ultrafiltration
- selective reabsorption
- excretion
What is the function of the glomerulus
Ultrafiltration
Describe the process of ultrafiltration?
- Blood enters the kidneys through the renal artery
- high blood pressure (caused by the afferent arterioles being wider than the efferent arterioles) forces liquid and dissolved solutes out of the blood
- tissue fluid collects in the Bowman’s Capsule
What is the glomerulus
a network of capillaries within the Bowman’s Capsule
Where does selective reabsorption happen
in the proximal and distal convoluted tubules
What percentage of reabsorption happens in the PCT
80%
What is reabsorbed in the PCT
- Na+
- Cl-
- glucose
- amino acids
- water
How are the cells of PCT adapted for its function
large surface area- microvilli
many mitochondria- for active transport of Na+
Why do the cells of the PCT contain many Mitochondria
ATP is needed for active transport of Na+ into the blood
What is the function of the Loop of Henle
to create an area of high solute concentration (and therefore low water potential) in the medulla
Describe how the Loop of Henle causes the reabsorption of water from the filtrate
- the Ascending Loop of Henle is more permeable to salts
- ions move out of the lumen of the Ascending Loop of Henle to the medulla by diffusion lower down the ascending Loop of Henle and by active transport further up
- this lowers the water potential of the medulla
- water moves out of the descending loop of Henle down its osmotic gradient and are absorbed into the blood
- this gradient also causes water to move out of the collecting ducts
- some Na+ and Cl- ions diffuse into the Descending Loop of Henle
What layers does the filtrate need to pass through to leave the blood and enter the Bowman’s Capsule
Endothelium (single cell layer of the capillaries)
Basement membrane- (glycoprotein and collagen mesh)
Podocyte layer- foot like projections that fit together with a gap
Describe the process of osmoregulation in a hydrated person
- blood water potential increases
- osmoreceptors in hypothalamus detect high water potential in the blood
- less ADH secreted by posterior pituitary gland
- DCT and CD less permeable to water
- less water reabsorbed from collecting duct
- less concentrated urine
Describe the process of selective reabsorption of Na+ from the lumen of the proximal convoluted tubule to the blood
- Na+ brought into the cells of the PCT down its concentration gradient through co transport with glucose and Cl- (from a high concentration in the lumen of the PCT to a low concentration of the cells of the PCT) PASSIVE
- glucose moves into the blood down its concentration gradient (facilitated diffusion- PASSIVE)
- Na+ actively transported out of cell into blood through Na+ K+ pump ACTIVE
What is the is the descending Loop of Henle permeable to
- water
- salts (Na+, Cl-)
What is the countercurrent multiplier mechanism
mechanism by which at all points in the loop of Henle the solute concentration is higher in the ascending Loop of Henle than the Descending Loop of Henle
What is the ascending Loop of Henle permeable to
salts only
in reality it is slightly permeable to water but a lot less than the descending loop
