Excretion Flashcards Preview

Biology F214 > Excretion > Flashcards

Flashcards in Excretion Deck (39):
1

Excretion

Removal of metabolic waste from the body.

2

Metabolic waste

It consists of waste substances that may be toxic or are produced in excess by the reactions inside cells.

3

Deamination

The removal of the amine group from an amino acid to produce ammonia.

4

Hepatic portal vein

Blood vessel that has capillaries at both ends- it carries blood from the digestive system to the liver.

5

Kupffer cells

Cells that breakdown and recycle old red blood cells.

6

Bilirubin

Waste product from the breakdown of haemoglobin.

7

Urea

Excretory product formed from the breakdown of excess amino acids.

8

Ornithine cycle

The process in which ammonia is converted to urea. it occurs partly in the cytosol and partly in mitochondria, as ATP is used.

9

Detoxification

The conversion of toxic molecules to less toxic or non-toxic molecules.

10

Nephron

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

11

Glomerulus

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

12

Selective reabsorption

Where useful substances are reabsorbed from the nephron into the bloodstream while other excretory substances remain in the nephron.

13

Afferent vessels

Brings blood into the organ.

14

Efferent vessels

Carry blood away from the organ.

15

Ultrafiltration

Filtration at a molecular level. Where in the glomerulus, large molecules and cells are left in the blood and smaller molecules pass into the Bowman's capsule.

16

Podocytes

Specialised cells that make up the lining of the Bowman's capsule.

17

Microvilli

Microscopic folds of the cell surface membrane that increase the surface area of the cell.

18

Co-transporter proteins

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

19

Facilitated diffusion

Diffusion that is enhanced by the action of proteins in the cell membrane.

20

Sodium-potassium pumps

Special proteins in the cell surface membrane that actively transport sodium and potassium ions against their concentration gradients.

21

Hairpin countercurrent multiplier

Arrangement of a tubule in a sharp hairpin so that one part of the tubule passes close to another part of the tubule with the fluid flowing in opposite directions. This allows exchange between the contents and can be used to create a very high concentration of solutes.

22

Osmoregulation

The control and regulation of the water potential of the blood and body fluids. In humans the kidney controls the water potential of the blood.

23

Distal convoluted tubule

The coiled portion of the nephron between the loop of Henle and the collecting duct.

24

Antidiuretic hormone (ADH)

Released from the pituitary gland and acts on the collecting ducts in the kidneys to increase their reabsorption of water.

25

Osmoreceptors

Receptor cells that monitor the water potential of the blood. If blood has a low water potential then water is moved out of the osmoreceptor cells by osmosis, causing them to shrink. This causes stimulation of the neurosecretory cells.

26

Hypothalamus

Part of the brain that contains neurosecretory cells and various receptors that monitor the blood.

27

Neurosecretory cells

Specialised cells that act like nerve cells but release a hormone into the blood. ADH is made in cell body and passed down axon to be stored in terminal bulb. If an action potential passes down the axon, then ADH is released from the terminal bulb.

28

Posterior pituitary gland

Hind part of the pituitary gland which releases ADH.

29

Half-life of a substance

Time taken for its concentration to drop to half its original value.

30

Dialysis

Use of a partially permeable membrane to filter the blood.

31

Dialysis membrane

Partially permeable membrane that separates the dialysis fluid from the patient's blood in a dialysis machine,

32

Dialysis fluid

Complex solution that matches the composition of body fluids.

33

Haemodialysis

Process when blood is taken from a vein and passed through a dialysis machine so that exchange can occur across an artificial partially permeable membrane.

34

Peritoneal dialysis

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

35

human Chorionic Gonadotrophin (hCG)

Hormone released by human embryos; its presence in the mother's urine confirms pregnancy.

36

Monoclonal antibodies

Antibodies that are identical as they have been produced by cells that are clones of one original cell.

37

Anabolic steroids

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

38

Gas chromatography

Technique used to separate substances in a gaseous state.

39

Chromatogram

Chart produced when substances are separated by movement of a solvent along a permeable material such as paper or gel.