13 1 excretion in humans

Excretion is the removal from the body of the waste products of metabolism, and any substances present in excess, e.g. excess salts

The metabolic waste products excreted by the lungs are water and carbon dioxide, both produced during respiration.

False. The kidneys excrete urea, excess water and ions. Carbon dioxide is excreted via the lungs.

Structures A-D are:

The role of the bladder is to store urine that is produced by the kidneys.

False. The urethra carries urine from the bladder to the exterior of the body. The ureters are a pair of tubes that connect the kidneys to the bladder

The kidney regions are:

Nephrons are tiny tubes found in the kidney. Each kidney contains many nephrons, the role of which is to produce urine.

True. The Bowman's capsule directly surround the glomerulus, a ball of blood vessels from which the blood filters into the nephron.

Filtration, or ultrafiltration occurs between the glomerulus and the Bowman's capsule.

Substances that are forced out of the capillaries during ultrafiltration are: These molecules form the glomerular filtrate.

False. Substances that are reabsorbed further along the nephron include: Urea and excess substances are not reabsorbed.

Components of the kidney filtrate are normally found in urine are:

The liver enables assimilation of amino acids by building them into new proteins which can then be used by the body.

Urea is formed from excess amino acids. This involves the following:

False. Urea is produced in the liver. The kidneys filter the urea, causing it to be excreted.

Deamination is the removal of the nitrogen-containing part of amino acids to form urea.

Urea needs to be excreted because it is toxic at high concentrations.