Excretion

Question 1

Excretion

Answer 1

removing metabolic waste from the body

Question 2

metabolic waste

Answer 2

waste produce from metabolism

Carbon dioxide form respiration and urea from deamination

Question 3

egestion

Answer 3

removal of undigested waste by defamation

Question 4

deamination

Answer 4

removal of ammonia from amino acids

Question 5

Respiratory acidosis

Answer 5

Effect of lowered blood pH (excess CO2)

Question 6

Why must nitrogenous compounds be removed from the body

Answer 6

This is because the body cannot store amino acids, but it would be toxic to excrete them

amino acids store lots of energy

Question 7

Hepatic Artery

Answer 7

brings oxygenated blood from aorta
25%

Question 8

Hepatic Portal Vein

Answer 8

Carries blood loaded with the products of digestion straight from the intestine to the liver (75% of the blood)

Question 9

Hepatic Vein

Answer 9

Connects to inferior vena cava and carries deoxygenated blood back to heart

Question 10

Sinusoids

Answer 10

connects the hepatic artery to the hepatic vein allowing hepatocytes to remove harmful substances from the blood

Question 11

Kuppfer cells

Answer 11

Hepatic macrophages that are attached to the walls of the sinusoids
Ingest foreign particles
Recycle old RBC’s

Question 12

What do hepatocytes do

Answer 12

Relatively unspecialised to carry out many functions
Synthesise proteins (enzymes and hormones)
Transform and store carbs (glycogen)
Synthesise cholesterol and bile salts
Form bile and secrete into bile canaliculi
Absorb substances from blood and also secrete products

Question 13

Shape of hepatocytes

Answer 13

Cuboidal w/ many microvilli (increases SA for contact w/ sinusoids)

Question 14

Role of the liver in excretion

Answer 14

Break down excess amino acids and haemoglobin
Detoxifies alcohol
Produces urea

Question 15

Basic functional unit of liver

Answer 15

Lobule

Question 16

Protein metabolism in the liver

Answer 16

Protein synthesis of plasma proteins
Deamination to form keto acid and NH2
Transamination to make new amino acids

Question 17

F ate of keto acids

Answer 17

Kreb’s cycle (respration)

Question 18

Where does deamination occur

Answer 18

In hepatocytes

Question 19

Equation of deamination

Answer 19

Amino acid + oxygen —> keto acid + ammonia

Question 20

Ornithine cycle

Answer 20

2NH3 + ornithine + CO2 (from respiration) —> H2O + urea (circulates in blood until filtered by kidney)

Question 21

Detoxification of alcohol

Answer 21

Alcohol is broken down by hepatocytes by alcohol dehydrogenase to make ethanal which is further dehydrogenated by ethanal dehydrogenase to make ethanoate
NAD is needed to oxidise and breakdown fatty acids

Question 22

Uses of ethanoate

Answer 22

Build up fatty acids

Cellular respiration

Question 23

Ultrafiltration

Answer 23

Afferent arteriole has larger diameter then efferent arteriole
high hydrostatic pressure is generated
endothelium wall of capillary has small pores/ fenestrations

Pressure is higher in the glomerulus then the Bowman’s capsule so fluid is pushed out

Question 24

3 layers between glomerulus and bowman’s capsule

Answer 24

endothelium: fenestrations
Basement membrane- stops removal of large substances
epithelium of Bowman’s capsule- Podocytes- finger like projections to ensure the passage of substances

Question 25

glomeruls filtrate

Answer 25

The fluid that filters through from the blood into the Bowman’s capsule

Question 26

selective reabsorption in PCT

Answer 26

membrane of epithelial cells in PCT actively transports sodium ions out of cytoplasm into the blood via the sodium potassium pump this lowers the concentration of sodium ions in the epithelial cells so sodium ions diffuse down concentration gradient back into cytoplasm passing through co transporter proteins each type of the co transporter proteins transports a sodium ion and another substance like glucose or amino acids

Question 27

which molecules are reabsorbed in the pct

Answer 27

All glucose in the glomerular filtrate is reabsorbed into the blood This means no glucose should be present in the urine Amino acids, vitamins and inorganic ions are reabsorbed The movement of all these solutes from the proximal convoluted tubule into the capillaries increases the water potential of the filtrate and decreases the water potential of the blood in the capillaries This creates a steep water potential gradient and causes water to move into the blood by osmosis A significant amount of urea is reabsorbed too The concentration of urea in the filtrate is higher than in the capillaries, causing urea to diffuse from the filtrate back into the blood

Question 28

reabsorption of water in the Loop of Henle and other

Answer 28

Descending limb permeable to water water is removed by osmosis into surrounding tissue bottom of loop of henle sodium and chloride ions diffuse out of loop of henley reducing water potential of surrounding tissue Ascending limb impermeable to water sodium and chloride ions are actively transported out of loop of henle decreasing water potential of surround tissue in the medulla. water is removed from urine in collecting duct water is reabsorbed in the DCT

Question 29

Haemodialysis

Answer 29

Heparin- stops blood clotting air bubbles removed before reentering the body blood form the patients vein is passed through tubes made from partially permeable membranes on the outside of the tube dialysis fluid flows in the opposite direction which contains same concentration of ions and glucose that the patients blood has

Question 30

peritoneal dialysis

Answer 30

a peritoneal layers of tissue that lies in abdominal cavity a catheter is inserted into the peritoneal cavity dialysis fluid is passed in and left there remaining fluid is drained of and replaced

Question 31

kidney transplant negatives and positives

Answer 31

new kidney not recognised as self different antigens present in kidney causing rejection by immune system immunosuppressant drugs required invasive procedure no longer needs dialysis all surgeries come wiv risks

Question 32

osmoregulation

Answer 32

osmoreceptors in hypothalamus detect low concentration of water in blood ADH is released from posterior pituitary gland transported to kidney in blood receptors on collecting duct are complementary to and specific to ADH so bind together this triggers a cascade of enzyme controlled reactions. whereby water channels called aqua potions form and fuse to membrane this removed water out of collecting duct and is reabsorbed by the blood

Question 33

low levels of ADH

Answer 33

cell membrane folds inwards creating new vesicles these remove aquaporins urine becomes more dilute

Question 34

pregnancy test

Answer 34

hCG is complementary shape to monoclonal antibodies hCG binds to them to form hCG antibody complex which moves up the stick wiv the urine excess antibodies are carried up with urine and bind to immobilise enzymes in the upper band - control hCG complex bind to immobilised enzymes in the lower band

Question 35

how to test for anabolic steroids

Answer 35

using gas chromatography