Excretion Flashcards
Define Excretion
The removal of metabolic waste from the body
Define deamination
The removal of the amine group from an aminoacid to produce ammonia
Define Egestion
Things that leave the body, and are unchanged by metabolic processes
Why is CO2 excreted?
As too much causes the carrying capacity of oxygen by the haemoglobin to decrease
To avoid carbonic acid being formed
What is respiratory acidosis?
When carbonic acid causes the blood pH to drop below 7.35,causing the breathing rate to increase to expell CO2.
Headaches, restlessness and HR all increase too
What can keto acids be used for?
Respiration
What does the Hepatic portal vein link?
The digestive system to the liver
Define Sinusoids
Channels that empty into the heptic vein
Define Hepatocytes
Liver cells that manafacture bile, proteins, and store carbohydrates
What are the functions of the liver?
Control of blood glucose, amino acid, and lipid levels
Detoxification of drugs and alcohol
Vitamin storage
Synthesis of bile, plasma proteins, and cholesterol
The ormithin cycle does what?
Converts ammonia to urea (by adding CO2)
Why does ammonia need to be converted to urea?
As ammonia is very soluble (so excretion would dehydrate too much)
And it is much more toxic
What is the pathway of the breakdown of alcohol?
And what is the product used for?
Ethanol»_space; Ethanal»_space; Ethanoic acid»_space; Acetyl CoA
Used in respiration (kreb cycle)
What causes Cirrhosis?
When too much alcohol is taken then there is not enough NAD for respiring fatty acids
So the fatty acids are converted to lipid, which accumulate in the livers hepatocytes
What is the Ureter of the kidney?
The tube connecting the kidney to the bladder (transports urine)
How does Ultrafiltration occur in the bowmans capsule?
Different diameters of afferant and efferant arterioles generate a high hydrostatic blood pressure in the glomerulus
Some small molecules pass through the basement membrane, between the podocytes in the epithelium cells of the bowmans capsule
This forms the glomerular filtrate in the lumen of the bowmans capsule
Explain how the pct works to selectively reabsorb certain molecules
Na+ ions activley transported out of the pct (via Na/K Pumps + ATP)
Glucose + amino acids + Na+ are diffused (by co-transporter proteins) into the pct from the filtrate
The increase of moleucles in the pct causes its WP to drop, so water moves into the pct via osmosis
These molecules then diffuse out of the pct and into the blood
The WP of the pct is high, so the water moves into the blood via osmosis
Large molecules can be reabsorbed by endocytosis
What type of cells are used to increase the surface area of the pct?
Microvilli
Explain how the loop of henle (L of H) reabsobs water
Na+ and Cl- diffuse into the descending limb
Water leaves the descending limb by osmosis and into the medulla
The ions then diffuse out of the base of the ascending limb and into the medulla
The ions are actively transported out of the ascending limb to form a high WP
The ascending limb is impermeable so water cant leave
Water moves via osmosis into the medulla at the collecting duct
What is the type of current that is present in the loop of henle to increase the efficiency of water reabsorption?
Hairpin Counter Current Multiplier
What job does the Dct do?
Uses active transport to adjust the concentration of salt in the urine
How is ADH released, and what affect does it have?
Osmoreceptors in the hypothalamus detect the WP of the blood
When the blood WP is low the osmoreceptor cells lose water and shrink
This shrinkage stimulates neurosecreatory cells
These cells release ADH into the posterious pituitury gland, and they are then released
ADH binds to the receptors on the cells of the collecting duct
Enzyme controlled reactions occur to cause vesicles containing aquaporins to be inserted into the plasma membrane
So the WP of the blood returns back to normal
What is the half life of ADH?
20 minutes
What is added to the blood in Haemodialysis to prevent clotting?
Heparin
Describe Peritonel dialysis
A permanent tube is surgically insterted into the abdomen
Dialysis fluid added to the tube to fill the space between the abdominal wall and the organs
The fluid is in for several hours at a time, and happens many times a day
Patient is free to do what they please during treatment (they are ‘free’)
What is the membrance of the tube in peritoneal dialysis made of?
Peritoneum
How do you test for pregancy?
Test stick contains monoclonal antibodies that bind to HCG
The antibodies are attatched to a blue beed
The HCG/antibody complex attatches to a strip of immobilized antibodies so that a blue line is formed
What are anabolic steroids?
Increase protein synthesis in cells
Remain in the blood for many days
