Module 2 Excretion
a. Define the term excretion
Excretion-The removal of metabolic waste from the body which are by products or unwanted substances from cell processes.
b. Explain the importance of removing metabolic wastes, including carbon dioxide and nitrogenous waste from the body
Excess carbon dioxide is toxic and has three main effects:
The majority of carbon dioxide is carried in the blood as hydrogencarbonate ions but in the process hydrogen ions are made inside red blood cells with carbonic anhydrase. These hydrogen ions compete with oxygen for space on the haemoglobin. Therefore too much carbon dioxide can cause a reduction in oxygen transportation. …show more content…
This lowers the pH by making the blood more acidic. If the change is small is leads to an increased breathing rate but if it is larger it can cause difficult breathing, drowsiness, headaches and confusion. It could cause a rapid heart rate and changes in blood pressure.
The body cannot store proteins or amino acids.
But because they contain a lot of energy, amino acids are transported to the liver where they get the toxic amino acid group removed via deamination.
The amino acid then forms the very soluble but highly toxic ammonium before being converted to urea and is then transported to the liver for excretion.
There is some remaining keto acid which can be respired or converted to a carbohydrate or fat for storage.
c. Describe the histology and gross structure of the liver
Supplies the liver with oxygenated blood from the heart.
The oxygen supplied is need for aerobic respiration.
Hepatic portal vein
This carries oxygenated blood to the liver.
The blood is rich in the products of digestion some of which may be toxic compounds.
This is where blood leaves the liver which then re-joins the vena cava.
Bile is secreted from the liver.
Bile has a digestive and excretory …show more content…
f. Describe the histology and gross structure of the kidney
g. Describe the detailed structure of a nephron and its associated blood vessels
h. Describe and explain the production of urine, with reference to the processes of ultrafiltration and selective reabsorption
1. Blood flows into the glomerulus from the afferent arteriole which is wider than the efferent arteriole which carries the blood away from the glomerulus.
2. This means that the blood in the capillaries is under increased pressure.
3. The blood pressure in the glomerulus is higher than in the Bowman’s capsule.
4. So fluid from the blood is pushed in the Bowman’s capsule.
5. Molecules with a higher molecular mass than 69,000 cannot get through the basement membrane so are held in the capillaries of the glomerulus. Molecules with a higher mass include most proteins and all blood cells.
6. The substances which are filtered out of the blood include: water, amino acids, glucose, urea and inorganic ions including sodium, chloride and potassium.
1. The sodium-potassium pumps remove sodium ions from the cells in the proximal convoluted tubule. This is done via active