Kidneys Flashcards
What is a hormone?
A chemical messenger released into the blood by an endocrine gland
List as many molecules as you can think of that leave the blood in ultrafiltration
Water, glucose, urea, minerals/salts (Na, K, Cl etc), amino acids, small proteins (e.g. some hormones). Bonus marks for any other small molecules like lactic acid, oxygen, carbon dioxide, ammonia!
What tissue type lines capillaries?
Squamous endothelium
Name the three layers between the glomerulus and the bowmans capsule
Squamous endothelium, basement membrane, podocytes
The pressure from the heart is trying to squeeze filtrate OUT of the blood, what is the correct term for this pressure?
Hydrostatic pressure
What pressure draws fluid back into the blood due to water potential differences?
Osmotic pressure
What’s the difference between the arteriole going into the glomerulus (afferent) and the one going out (efferent)?
Afferent is wider than efferent
Can glucose pass through the basement membrane?
Yes
Are large proteins present in the filtrate?
No, they are too large to pass through the basement membrane. If present the basement membrane is damaged
Which filtered substances are reabsorbed in the PCT?
Water, glucose, amino acids, minerals/salts
Which substances are in human urine?
Urea, water, some other waste materials (e.g. ammonia, uric acid)
Define homeostasis
Maintenance of a constant internal environment
Give the steps in a flow chart showing negative feedback
Receptor, Coordinator, Effector, Response
What are the functions of a kidney?
Filtering the blood and osmoregulation
What is the difference between egestion and excretion?
Egestion is the removal of undigested food from the body (faeces) and excretion is the removal of waste made by the body (eg in urine)
What happens to excess amino acids?
Deamination in the liver. The amino group is removed to form ammonia then converted to urea, the rest is converted to a keto acid and either respired or stored
How are the cells of the PCT adapted for selective reabsorption?
Microvilli and basal channels give large surface area, many mitochondria, tight junctions
How are glucose and amino acids reabsorbed from the filtrate into the blood?
Co transport with sodium ions through the cells of the PCT
What is the main function of the loop of Henle?
The ascending limb actively transporting ions out of the filtrate into the medulla tissue fluid to lower the water potential.
Which parts of the loop of Henle are permeable/impermeable to water?
The descending limb is permeable, the ascending limb is impermeable
When the blood water potential is low, what is the receptor, coordinator, effector and response?
It is detected by osmoreceptors in the hypothalamus, ADH is released from the posterior pituitary gland, this travels to the collecting duct, which becomes more permeable to water (smaller volume of more concentrated urine produced)
How does antidiuretic hormone make the collecting duct more permeable to water?
It causes more aquaporins to be added to the membrane on the side next to the lumen. These aquaporins are stored in vesicles which fuse with the membrane.
Give an advantage of kidney transplant
The patient no longer needs dialysis
Give two disadvantages of kidney transplant
There may be a shortage of organs- there must be donors, and the recipient must stay on immunosuppressants for life
What are the two types of kidney dialysis?
Haemodialysis and Peritoneal dialysis.
Which nitrogenous waste is excreted by birds and why?
Uric acid, because it is less toxic than ammonia and urea so requires less water to dilute it. This means birds lose less water and have to carry less water for flight
Which nitrogenous waste is excreted by mammals and why?
Urea, because it is less toxic than ammonia so requires less water to dilute it- good for terrestrial animals
Which nitrogenous waste is excreted by fish and why?
Ammonia. It is highly toxic so needs to be diluted by a lot of water for excretion, but this is fine for aquatic animals.
What is the relationship between the length of the loop of Henle and the water availability of the environment?
The less water available the longer the Loop of Henle will be
