ORTCITIAEE: Control of blood water potential Flashcards
What is the main role of the kidneys?
Filter blood and produce urine.
What are the two main things that filtering blood and producing urine does?
- Removes harmful waste products (e.g. urea)
- Controls the water potential of the blood- osmoregulation.
What is osmoregulation?
The process of regulating the water potential of the blood.
What will happen to cells if the bloods water potential is too low?
Water will move out of the cell and it will shrivel.
What will happen to cells if the blood water potential is too high?
Water will move into the cell and it will burst (lysis).
What do nephrons do?
Filter the blood.
What are the 5 main structures of a nephron?
- Glomerulus
- Bowman’s capsule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting duct
What is the glomerulus?
A mass of blood capillaries
What supplies the glomerulus with blood?
The afferent arteriole
What carries blood away from the glomerulus?
The efferent arteriole
The ________ _________ branches into a network of capillaries that surround the rest of the nephron and ensures there is a short diffusion pathway to the blood.
efferent arteriole
Give the order of the nephron structures:
-Glomerulus
-Bowmans capsule
-Proximal convoluted tubule
-Loop of Henle
-Distal convoluted tubule
-Collecting duct
Blood within the glomerulus is kept at a VERY _____ pressure.
High
Why is blood within the glomerulus kept at a very high pressure?
Forces substances out of the blood and into the Bowman’s capsule.
What are the three filters that substances need to pass through to get from the blood to the lumen of the Bowman’s capsule?
- Endothelium
- Basement Membrane
- Podocytes
Basement membrane have pores which are sieve like structures- what is the function of these?
Act as sieves- controlling the size of substances that pass through.
Which 4 substances can pass through the 3 filters to get from the blood into the Bowmen’s capsules lumen, and which 1 can’t?
Can:
Water
Ions
Glucose
Urea
Can’t:
Protein
What is ultrafiltration of the blood?
Forcing substances from the blood into the Bowman’s capsule.
Which 4 substances is the glomerular filtrate made up of?
Water
Ions
Glucose
Urea
______ ________ is when useful substances get reabsorbed back into the blood.
Selective Reabsorption.
Explain the process of selective absorption between the capillary, epithelial cell and tubule lumen:
1) Sodium ions from the epithelial cell move into the capillary via active transport, creating a conc gradient between epithelial cell and tubule lumen.
2) Sodium ions from the tubule lumen move into the epithelial cell via transport proteins via facilitated diffusion, and also allowing co-transport with other substances.
3) Sodium ions and other substances can diffuse into the blood from the epithelial cell.
4) The movement of substances into the epithelial cell creates a water potential gradient between the epithelial cell and tubule lumen, so water moves from the lumen into the epithelial cell via osmosis.
Where does selective reasbsorption take place?
Proximal convoluted tubule
What are the main adaptations of the proximal convoluted tubule?
1) Contains mitochondria to produce ATP
2) Large number and variety of co-transport proteins to allow facilitated diffusion and co-transport (for selective reabsorption).
3) Microvilli to increase the surface area for diffusion.
4) Short diffusion distance through one cell which increases the rate of reabsorption.
What are the two main parts of the Loop of Henle?
Descending Limb
Ascending Limb
