5.1.2 excretion as an example of homeostatic control Flashcards
What is excretion?
Excretion is the removal of waste products of metabolism from the body
What is metabolism?
All the chemical reactions that happen in your cells make up your metabolism
- convert food and drink into energy
What does metabolism produce?
Metabolism produces waste products
What are waste products?
Substances that arent needed by the cells
What waste products does metabolism produce?
1- carbon dioxide
2- Nitrogenous (nitrogen-containing) waste
Why is it so important to remove these metabolic waste products from our body?
Many of these products are toxic, a build up of them in the body would cause damage EG: affecting other metabolic reactions
How does excreting waste products from the body affect our metabolism and homeostasis?
Excreting waste products from the body maintains normal metabolism.
It also maintains homeostasis by helping to keep the levels of certain substances in the blood roughly constant
What are the functions of the liver?
1- Excess amino acids are broken down by the liver
2- The liver removes other harmful substances from the blood - detoxification
3- The liver stores glycogen
Where do we get amino acids in our body from?
One of the livers most important roles is getting rid of excess amino acids produced by eating and digesting proteins
Why is excess amino acids broken down by the liver?
Amino acids contain nitrogen in there amino groups and nitrogenous waste can not usually be stored by the body. This means that amino acids are and can be damaging to the body so they either must be
1) USED by the body (eg: making proteins)
OR
2) To be broken down and excreted
How are amino acids get broken down by the liver?
ORTHITHINE CYCLE
The amino group gets removed from the amino acid which leaves us with ammonia and organic acids … this process is called DEAMINATION
What happens in the ornithine cycle?
Urea is formed from ammonia reacting with CO2
Other than amino acids, what other harmful substances does the liver breakdown?
Alcohol
Drugs
Unwanted hormones
What happens to products like alcohol, drugs and unwanted hormones in the body in the liver ? Process name..
DETOXIFICATION
- They are broken down into less harmful compounds that can then be excreted from the body
What are the 4 veins/arteries/ducts connected to the liver?
1- Hepatic vein
2- Hepatic artery
3- Hepatic portal vein
4- Bile duct
What does the hepatic artery do?
Hepatic artery supplies the liver with oxygenated blood from the heart so that the liver has a good supply of oxygen for respiration providing plenty of oxygen for respiration, providing plenty of energy
What does the hepatic vein do?
Takes deoxygenated blood away from the liver
What does the hepatic portal vein do?
brings blood from the small intestine so its rich in the products of digestion
What does the bile duct do?
Takes bile to the gall bladder to be stored
What is bile?
A su`qwbstance produced by the liver to emulsify fats
Look at an image of a stained section of liver tissues
What are 2 functions of the kidneys?
1- Excrete waste products EG: urea produced by the liver
2- Regulate water potential in the blood
Where does blood enter the nephron from?
Renal artery
What are nephrons and how many are there in each kidney?
Nephrons are long tubules along with bundles of capillaries where the blood is filtered … one million in each kidney
After blood enters from the renal artery where does it go?
To the afferent arteriole
What happens to the afferent arteriole?
It splits into a structure called a glomerulus
What is a glomerulus?
A bundle of capillaries looped looped inside a hollow ball
What is the hollow ball that the glomerulus is in called?
Bowmans capsule
What process happens at the Bowmans capsule ?
Ultrafiltration
What is an afferent arteriole
The arteriole that takes blood into each glomerulus
What is an efferent arteriole
The arteriole that takes blood away from the glomerulus
What is the difference between the afferent arteriole and the efferent arteriole in terms of size and what does this cause?
Efferent diameter is much smaller in size which results in a high pressure of the blood in the glomerulus
What does the blood high pressure in the glomerulus cause?
The high pressure forces liquid and small molecules in the blood out of the CAPPILLARY and into the Bowmans capsule
What three layers do the liquid and small molecules go through to get to the Bowmans capsule?
1- Capillary wall
2- A membrane called the “basement membrane”
3- Epithelium of the Bowmans capsule
What are some examples of things that can not pass through to the Bowmans capsule and hence stay in the blood?
Proteins
Blood cells
Now that the liquid and small molecules are in the Bowmans capsule, what are they called?
Filtrate
What part of the nephron comes after the glomerulus?
The Proximal conjugated tubule
What happens at the proximal conjugated tubule?
Selective reabsorption
