BIOLOGY · Stage 9 · Chapter 10: Excretion in Humans
Biology 10.6 Chapter 10 Review: Excretion in Humans
5 min read 5 parts Lesson 6 of 6
Lesson summary
10.6 Chapter 10 Review: Excretion in Humans — Alhussan International Academy — Biology (Stages 7–9) notes: Revise the products and organs of excretion, kidney function, kidney failure, models and osmoregulation from Chapter 10.Excretion — the removal of metabolic waste and of sub…
- Renal artery
- Glomerulus
- Urine path
- Renal vein
- Precise terms
- Too little water
Section 1 of 5Excretion and its organs
- Excretion
- the removal of metabolic waste and of substances in excess.
- Lungs
- carbon dioxide leaves through the lungs.
- Kidneys
- urea, excess water and salts leave in urine.
- Skin
- it loses water, salts and a little urea in sweat.
- Urea
- it is produced in the liver from excess amino acids by deamination, in which the amino group is removed.
- Egestion
- faeces are egested, not excreted.
Section 2 of 5The urinary system and nephron
- Renal artery
- it brings blood to each kidney, where the nephrons filter it.
- Glomerulus
- high pressure forces water, glucose, salts and urea into the capsule, while proteins and blood cells stay in the blood.
- Tubule
- all the glucose and as much water and salt as needed are reabsorbed.
- Urine path
- the rest flows to the ureter, is stored in the bladder and passes out through the urethra.
- Renal vein
- it carries away blood that has less urea.
- Precise terms
- filtration is by size, reabsorption is selective, and urine is formed from what is left.
Section 3 of 5Water balance
- Too little water
- the pituitary gland releases more ADH, the kidneys reabsorb more water, and a small volume of concentrated urine is made.
- Too much water
- less ADH is released and a large volume of dilute urine is produced.
- Urine output after a drink
- it rises quickly, peaks and then returns to the normal rate as the extra water is removed.
- Freshwater fish
- they excrete large amounts of dilute urine.
- Marine bony fish
- they excrete small amounts of concentrated urine and remove salt through the gills.
- Adapted mammals
- kidneys differ with the habitat, for example camels and kangaroo rats make concentrated urine and beavers make dilute urine.
Section 4 of 5Kidney failure and treatment
- Effect
- waste builds up in the blood.
- Dialysis
- blood passes along a partially permeable membrane with dialysis fluid on the other side.
- Urea diffuses out of the blood into the fluid.
- Glucose stays in the blood because the fluid already contains it.
- Transplant
- it is a long-term solution but carries the risk of rejection and needs immunosuppressant drugs.
Section 5 of 5Models of the kidney
- Purpose
- a model helps explain something that cannot easily be seen.
- Evaluating
- say what each part stands for and mention its limitations.
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