F214 REVISION- EXCRETION

Define Excretion

The removal of metabolic waste from the body.

Name the main 2 substances excreted by the body Carbon dioxide from respiration

Nitrogen-containing compounds such as urea

Complete the following sentences: Carbon dioxide combines with water

in the blood to form Carbonic acid

This dissociates to form hydrogencarbonate ions and Hydrogen ions

This occurs under the influence of the enzyme carbonic anhydrase

Label the following

Hepatic VeinHepatic Portal Vein

Hepatic Artery

Bile Duct

Sinusoid

Kupffer Cell

What is the role of the Kupffer cells Kupffer cells are specialised

macrophages. They move within the sinusoids and are involved in the breakdown and recycling of old red blood cells

Name 3 functions of the liver

Control of blood glucose levels, amino acid levels, lipid levels

Synthesis of red blood cells in the fetus, bile, plasma proteins, cholesterol

Storage of vitamins A, D and B12, Iron, glycogen

Breakdown of hormones Destruction of red blood cells

Outline what happens during deamination Reacts with oxygen

Produces Ammonia and Keto acid

Have a go at the following past exam question

Fill in the gaps

Alcohol is broken down by hepatocytes by the action of the enzyme ethanol dehydrogenase. This produces ethanal which is dehydrogenated further by the enzyme ethanal dehydrogenase. The final compound is ethanoate which combines with coenzyme A to form acetyl coenzyme A. The hydrogen ions produced in this process combine with NAD to produce reduced NAD.

Label the following

Efferent Arteriole

Renal Vein

Glomerulus

Afferent arteriole

Loop of Henle

Proximal Convoluted tubule

Bowman’s Capsule

Collecting Duct

Where is most of the water reabsorbed?

a) Proximal Convoluted tubule

b) Loop of Henle

c) Distal Convoluted tubule

d) Collecting duct.

Past exam question

Why does the water potential decrease as you go down the descending limb? Loss of water by osmosis to

surrounding tissue Diffusion of sodium and chloride ions

into the tubule

State 3 sources where water is gained Food

Drink

Metabolism

Fill in the boxes for the following flow diagram:

Increase in water potential

Decrease in water potential

Detected by osmoreceptors in hypothalamus

Detected by osmoreceptors in hypothalamus

Less ADH produced

Collecting duct wall less permeable

Less water reabsorbed

More ADHproduced

Collecting duct wall more permeable

More water reabsorbed

Decrease in water potential

Increase in water potential

Normal Water potential in blood

Explain how kidney Dialysis works Removes wastes, excess fluid and

salt from the blood Dialysis membrane is partially

permeable The dialysis fluid contains the correct

concentration of salts, urea, water and other substances in blood plasma

Any substance in excess diffuses across