NA. 5.2 Excretion Flashcards
What is Excretion?
Process of removing metabolic wastes from the body
What products must be Excreted?
- carbon dioxide
- nitrogen based by-products
- other compounds like bile and faeces
What is Egestion?
the elimination of faeces from the body
Why is Excretion Important?
the organism to maintain its PH balance and regulate osmotic pressure whiles also removing waste that mat become toxic if it builds up
what are some of the Excretory organs?
- The Lungs (excretes respiratory waste)
- The Liver (excretes metabolic & nitrogenous waste)
- The Kidneys (excretes urea to bladder (to be peed out)
- the Skin (excretes hella stuff)
Why would we NOT want CO2 buildup in the blood?
CO2 reacts with water in the blood plasma or Red blood cells to form carbonic acid
this disassociates into H+ ions and hydrogen carbonate ions. These Hydrogen ions then affect the PH
• In plasma it reduces the PH affecting the blood
• In erythrocytes they affect haemoglobins tertiary structure, decreasing its oxygen affinity
• H+ can bind to haemoglobin forming haemoglobonic acid which cant even carry oxygens
• CO2 can bind to haemoglobin forming carbaminoglobin which cant carry oxygens either
What is the liver?
An ORGAN (1) that breaks down harmful substances and toxic waste into less harmful forms, ready to be disposed
What are Liver cells called?
Hepatocytes, cuboidal shaped cells with lots of microvilli
Describe the gross structure of the Mammalian Liver
Liver lobules (cylinders of hepatocytes arranged in rows & connected at the centre) are connected to:
hepatic vein takes deoxygenated blood away from the liver & is attached to → hepatic portal vein: contains products of digestion & hepatic artery: supplies oxygenated blood via Sinusoid capillaries.
And bile duct: transports bile to gall bladder for storage.
Outline the functions of the Mammalian Liver
- Site of gluconeogenesis, glycolysis, glycogenesis.
- Stores glycogen.
- Deaminates excess amino acids, forming ammonia & organic acids. Acids can be respired or converted into glycogen. Ammonia is detoxified by addition of CO2 in ornithine cycle.
- Detoxifies chemicals e.g. converts alcohol to ethanal then acetic acid.
What does the Hepatic Artery do?
carries oxygenated blood from the heart into the liver
What does the Hepatic Vein do?
carries deoxygenated blood into the liver from the digestive system, this is the blood in need of filtration and contains toxic substances in high concentrations
What does the Hepatic Portal Vein do?
carries deoxygenated blood from the liver into the heart
What is the Bile duct?
consist of bile caniculi which join together to form a vessels that carries bile from the liver to the gall bladder where it is stored until use
What are the Interlobular vessels?
the blood vessels that run between the liver lobules (Hepatic Artery & Hepatic Portal Vein)
What are the intralobular vessels?
the blood vessels that run through the liver lobules (Hepatic Vein)
What are Kupfer cells?
Specialised Macrophages in the liver that move about the sinusoids that breakdown and recycle old red blood cells
Where is Bile made?
in the Liver cells
What happens in the sinusoid?
after blood from the hepatic portal vein and artery mix they pass through the sinusoid which is lined with liver cells that remove and return certain substances to the blood
What is the function of the Gall bladder?
Stores Bile
What is the step by step for detoxification of alcohol?
Ethanol+ Ethanol dehydrogenase → Ethanal + 2H
Ethanal+ Ethanal dehydrogenase → Ethanoic Acid +2H
Ethanoic Acid → ecetyl coenzyme A for respiration
*the 2H produced in steps 1 & 2 are used in reducing NAD and forming NADH(reduced NAD)
What is Deamination?
Provide the equation that accompanies the process
the process of removing the amino group from an amino acid, making ammonia and a Keto acid
Amino Acid + O2 → Ammonia + Keto acid
What is the role of the Ornithine cycle?
By combining the highly toxic ammonia with carbon dioxide it can be converted into the less toxic urea and water
Outline the reactions that occur in the Ornithine cycle
Ammonia + CO2 + Ornithine → citrulline + H20
Ammonia + citrulline → Arginine + H20
Arginine + H20 → Urea + Ornithine
Urea formation process equation?
Amino acid → Ammonia + keto acid → Urea
↑ ↑
Deamination Ornithine
What is the Kidney?
the two organs in the body responsible for excretion, the process of removing waste from the blood and producing urine is done here