Kidneys Flashcards
Describe the role of the loop of Henlé in osmoregulation
- Filtrate moves into the descending limb of the loop of Henlé. Water moves out of the descending limb by osmosis
- At the bottom of the LoH (hairpin bend) the filtrate has a low water potential as it has a very high concentration of solutes
- Ions rapidly diffuse out of the ascending limb into the medulla which creates a very low WP in the medulla tissues
- Further up the ascending limb, ions (Na+, Cl-) are actively transported out of the ascending limb
- At the top of the collecting duct, there is a very high WP so water moves out of the collecting duct by osmosis
Describe the role of ADH in osmoregulation
- osmoreceptors in the hypothalamus detect a low WP
- sends signal to posterior pituitary gland which secretes ADH
- ADH binds to receptors on the cell surface membrane
- Aquaporins fuse to membrane which increases permeability of collecting duct
- WP increases and returns to set point
Describe the gross structure of the kidney
Cortex, medulla, pelvis
- renal artery, renal vein
State the blood vessels of the liver
Hepatic vein (takes blood away)
Hepatic portal vein (wider, blood from intestines/ digestive system)
Hepatic artery (narrow, blood from aorta - into liver)
State 3 functions of the liver
- glycogen storage
- detoxification
- deamination
Define excretion
Removal of metabolic waste products from the body
Explain each function of the liver
Detoxification
- hepatocytes secrete catalase which breaks down hydrogen peroxide
- hepatocytes release alcohol dehydrogenase
Ethanol —> Ethanal Ethanal —> ethanoate
Ethanol is absorbed and transported in the blood until it reaches hepatocytes
Hepatocytes release enzyme alcohol dehydrogenase which converts ethanol into ethanal
Deamination
- remove amine group from amino acid
- forms ammonia (toxic and highly soluble)
- ornithine cycle
- urea is produced
How do freshwater fish, mammals and birds excrete
Freshwater fish- ammonia
Mammals- urea
Birds- uric acid
Where does ultrafiltration occur
Glomerulus
What happens in ultrafiltration
- Salts, water, urea and glucose diffuse out of the glomerulus into the bowman’s capsule
- WBC’s, RBC’s, platelets are too large to pass through fenestrations in B.C
Afferent and efferent arterioles
What makes up glomerular filtrate
Water, urea, amino acids, inorganic ions
Where does selective reabsorption occur
PCT
What 4 things are selectively reabsorbed
Glucose, water, sodium, amino acids
3 adaptations of PCT
- microvili (large SA)
- mitochondria
- Co transporter molecules
3 things DCT does in selective reabsorption
- pH regulation
- ion reabsorption
- water reabsorption
