Bio 4: Excretion Flashcards Preview

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Flashcards in Bio 4: Excretion Deck (31):
1

Excretion

Removal of metabolic waste from the body

2

Metabolic waste

The waste substances that may be toxic or are produced in excess by the reactions inside cells. E.g. CO2 and urea

3

Carbon dioxide (as waste)

Passed from cells of respiring tissues. It is toxic in excess.
+Travels as hydorgencarbonate, this forms hydrogen ions that compete with oxygen for space on haemoglobin.
+Form carbaminohaemoglobin, reducing oxygen transport
+Respiratory acidosis, lower blood pH, blood becomes more acidic. Significant changes cause drowiness, headaches, confusion and even death.

4

Urea (as waste)

Produced by deamination. This makes ammonia, which converted into urea, which is taken to the kidney.
Keto acid is used in respiration or for storage.

5

Deamination

Removal of amine group from an amino acid to produce ammonia.

6

Hepatic artery

Takes the oxygenated blood from the aorta into the liver

7

Hepatic portal vein

Takes the deoxygenated blood from the digestive system to the liver.

8

Hepatic vein

Blood leaves the liver, joins the vena cava

9

Bile duct

Carries bile from the liver to the gall bladder

10

Kupffer cells

Specialised macrophages that move in sinusoids. They breakdown and recycle old red blood cells. One product is bilirubin.

11

Ornithine cycle

Process in which ammonia is converted to urea. It occurs partially in the cytosol and partly in mitochondria, as ATP is used.
Ammonia and carbon dioxide makes urea and water

12

Alcohol detoxification

Ethanol is dehydrogenated to ethanal, then again to ethanoic acid. The final compound is acetate. This is combined with coenzyme A forming acetyl coenzyme A.

13

Nephron

Functional unit of the kidney. Microscopic tubule that receives fluid from the blood capillaries in the cortex and converts this to urine, which drains into the ureter.

14

Glomerulus

Fine network of capillaries that increases the local blood pressure to squeeze fluid out of the blood. It is surrounded by a cup - or funnel-shaped capsule which collects the fluid and leads to the nephron.

15

Selective reabsorption

Useful substances are reabsorbed from the nephron into the bloodstream while other substances remain in the nephron.

16

Ultrafiltration

Filtration at a molecular level

17

Podocytes

Specialised cells that make up the inner lining of the Bowman's capsule. They have finger like projections called foot processes. This ensures there are gaps between the cells.

18

Basement membrane

Fine mesh of collagen fibres and glycoproteins. This acts as a filter prevent large molecules getting through. Blood cells and proteins cannot get through. Water, amino acids, glucose, urea and inorganic ions can get through.

19

Co-transporter proteins

Proteins in the cell surface membrane that allow facilitated diffusion of simple ions to be accompanied by transport of a larger molecule such as glucose.

20

Osmoregulation

Control and regulation of the water potential of the blood and body fluids. This is the kidney in humans.

21

Loop of Henle

A descending limb into the medulla and an ascending limb into the cortex. This allows salts from the ascending limb into the descending. This increase the concentration in the tubule fluid, and causes them to diffuse out into the medulla.

22

Cortex has high water potential because...

+ at the base sodium and chloride ions diffuse out of tubule
+high up, they are transported out
+ascending wall is impermeable to water (no water loss here)

23

Distal convoluted tubule

In the cortex, between the loop of Henle and the collecting duct

24

Collecting duct

Tubule fluid has a high water potential, water is lost depending on the presence of aquaporins. This lost by osmosis. The duct goes back into the medulla.

25

ADH

Antidiuretic hormone, is released from neurosecretory cells in the pituitary gland and acts on the collecting ducts in the kidneys to increase their reabsorption of water. More ADH means more aquaporins are inserted into the collecting duct, this means more water is reabsorbed, and there is less urine.

26

Osmoreceptors

Receptor cells that monitor the water potential of the blood.

27

Haemodialysis

Blood is taken from a vein and passed through a dialysis machine so that exchange can occur across an artificially partially permeable membrane.
Heparin is added to avoid clotting.

28

Peritoneal dialysis

Dialysis fluid is pumped into the body cavity so that exchange can occur across the peritoneum..

29

Human chorionic gonadaotrophin

The hormone released by human embryos, it's presence in the mothers urine as early as 6 days after conception confirms pregnancy.

30

Monoclonal antibodies

Identical because they have been produced by cells that are clones of one original cell.

31

Anabolic steroids

Drugs that mimic the action of steroid hormones that increase muscle growth.