Excretion

Frage	Antworten
Define Excretion.	The eliminating of waste products of metabolism
what is Urea made from and where is it made?	the combination of ammonia and carbon dioxide Made in the liver
What are the sides effects of having to much protein which leads to too much Urea?	1. Tiredness 2. Nausea and vomiting 3. Headaches 4. Bad taste in the mouth 5. Bad breath 6. Poor memory and concentration
what blood vessels are present in the Liver?	1. Hepatic artery 2. Hepatic portal vein 3. hepatic vein
what are the features of the Hepatic artery?	Carries oxygenated blood into the liver
what are the features of the Hepatic portal vein?	carries nutrient rich blood - de-oxygenated high concentration of glucose and amino acids. comes from the small intestine
what are the features of the Hepatic vein?	carries de-oxygenated blood away from the liver to the Vena Cava and back to the heart.
what is the liver tissue made up of?	Lobules
What are the lobules made up of?	hepatocytes
what is the function of the sinusoids?	carry blood to the central vein from the hepatic portal vein and hepatic artery
What is the function of Bile Canaliculi?	Carry bile to bile duct in portal canal.
What is the function of the Kupffer Cells?	contain phagocytic macrophages that engulf bacteria present in blood.
What is deamination?	the removal of the amine group from an amino acid
what happens during deamination?	The amino acid group is removed and from ammonia and a keto acid.
why is ammonia very toxic?	It is very soluble and froms an alkaline solution
How is Urea formed?	The ammonia is combined with CO2 using ATP
Where does the detoxification of alcohol happen?	In the smooth endoplasmic reticulum of hepatocytes.
what is the process of deamination?	1. Ethanol dehydrogenase converts the ethanol to ethanal. 2.Aldehyde dehydrogenase then converts the ethanal to ethanoate
What is needed during deamination?	Oxidised NAD
What substances (other than alcohol) are removed in the kidneys and why?	1. Hormones- prevent long lasting effects 2. Medicinal drugs
what could an excess amount of alcohol cause in the liver.	Fatty liver, which may develop into Cirrhosis.
What does Cirrhosis cause?	The ammonia to build up- can lead to damage to the CNS and can cause coma/death.
why is it important to remove metabolic waste ( CO2)?	1. It may denature enzymes due to the change in pH. 2. Transport proteins are affected.
What is the gross structure of the kidney?	cortex, medulla, pelvis
What are the two stages of forming urine?	1. Ultrafiltration 2. Selective reabsorption
where does ultrafiltration occur?	In the Bowman's capsule- all in the cortex of the kidney
How is the blood pressure maintained during Ultrafiltration?	The afferent arteriole leading to the glomerulus is wider than the efferent arteriole leading out
What is the process of Ultrafiltration?	The process when blood plasma is forced out from blood vessels in bowman's capsule. Only small molecules will pass through the blood vessel such as sodium ion, potassium ion, urea.
What size are the molecules that are not able to pass through the basement membrane?	molecules with a relative molecular mass of over 69,000
Why can the water in the filtrate not move back into the capillaries?	Because of the high hydrostatic pressure generated in the carpillaries
What are Podocyte cells?	Cells i the Bowman's capsule that have finger like projections
Where does Selective reabsorption take place?	In the Proximal Convoluted Tubule.
What is the process of Selective reabsorption?	It is the process by which certain substances that are required by the body (such as glucose, amino acids, vitamins and water) that have been filtered out of the blood during ultrafiltration, are reabsorbed.
What happens during selective reabsorption?	The Na+ is actively pumped out of the inner membrane of the PCT. This causes the conc. of Na+ in those cells to drop and the Na+ passively enters the epithelial cells. The Na+ ions are co-transporters- bring in other substances (glucose). Water is reabsorbed by osmosis down the water potential gradient.
What is the role of the Loop of Henle?	To create a very low water potential in the Medulla.
What are the stages of reabsorption in the loop of Henle?	1. fluid passes down loop- becomes more concentrated (salt diffuses out) 2. Fluid moves up loop- becomes more dilute. 3. This passes salts from ascending limb to descending limb = increasingly concentrated, 4. creates concentration gradient in medulla. 5. water potential is v. low 6. fluid passes along collecting duct- water is withdrawn by osmosis into tissue fluid. 7 results in urine- conserves water
What does the Distal Convoluted Tubule do?	Actively absorbs sodium ions
What is the name given to the hormone that alters the permeability of the collecting duct?	Anti- diuretic Hormone (ADH)
How does ADH alter the permeability of the collecting duct?	1. Cells in the wall of the collecting duct have membrane receptors for ADH. 2. ADH binds to the receptors and cause a series of enzyme-controlled reaction inside the cell. 3. The end result id to insert aquaporins in the walls of the collecting duct.

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