excretion

Question 1

what is the function of the liver

Answer 1

breaks down toxic substances like as alcohol

Question 2

how does the liver break down amino acid

Answer 2

.amine groups are removed via deamination producing ammonia and organic acids
.organic acids are used for ATP or stored glycogen
.ammonia combines with CO2 to form urea via ornithine cycle occurring in the mitochondria
.urea is excreted from liver cell enters bloodstream and filtered out body as urine

Question 3

what substances are detoxified by liver

Answer 3

.alcohol- alcohol dehydrogenase breaks ethanol to ethanal to ethanoate
.hydrogen peroxide- catalase breaks oxygen and water
.paracetamol
.insulin

Question 4

function of the liver in regulation blood glucose

Answer 4

.converts excess glucose into glycogen
.stores glycogen within its cells
.releasing glucose into the bloodstream by breaking down glycogen

Question 5

function of liver in breaking down red blood cells

Answer 5

haemoglobin is broken down into hepatocytes into bile pigments
.excreted by bile duct to the gallbladder

Question 6

key structures of the liver

Answer 6

hepatic artery- supplies oxy blood

hepatic vein = carries away deoxy blood towards heart

hepatic portal vein = brings nutrient rich blood from intestines

bile duct = transports bile to gallbladder

Question 7

structure of liver lobules

Answer 7

hepatocytes arranged along channels(sinusoids)

sinusoids is where oxy rich blood meets nutrient rich blood from portal

branch of hepatic vein is at the centre to remove deoxy blood

Kupffer cells ingest pathogens

bile canaliculus links to a branch of the bile duct

Question 8

kidney anatomy

Answer 8

receive oxy blood via renal arteries

filtered in the kidneys and the resulting urine passes into ureters which transports it to the bladder

urine is stored in the bladder and is removed from the body via urethra

renal vein returns filtered blood to heart via vena cava

Question 9

internal structure of the kidney

Answer 9

fibrous capsule = outer membrane that protects the kidney

renal cortex = outer region that contains bowman’s capsules, convoluted tubules and blood vessels

renal medulla- inner region that contain pyramids that contains the loops of Henle, collecting ducts and blood vessels

renal pelvis= cavity that collects urine into ureters

Question 10

function of nephrons

Answer 10

filters blood and reabsorbs useful substances and removes waste

Question 11

how does filtrate move through the nephrons

Answer 11

.in the Bowmans capsule filtrate is formed in the glomerulus

.then it moves to the PCT where it reabsorbs useful substances(water, glucose, salts) into surrounding capillaries

.its moves to the loop of Henle which creates a high solute gradient in the medulla

.at the DCT the water balance is tuned by reabsorbing water into capillaries

.the collecting duct collects filtrate from nephrons and further water tunes before urine formed is passed to bladder

Question 12

blood vessels associated with the nephron

Answer 12

afferent arteriole = supplies glomerulus with blood

glomerulus = fluid is forced out of the blood within it into the bowman’s capsule through ultrafiltration

efferent arteriole = carries blood away from glomerulus

Henle = absorb salts, glucose and water

Question 13

what is ultrafiltration

Answer 13

when water, glucose, mineral ions and urea are filtered out of the blood into the bowman’s capsule to form glomerular filtrate

Question 14

ultrafiltration process

Answer 14

.blood enters the glomerulus through afferent arteriole
.blood leaves glomerulus via smaller efferent arteriole maintaining high hydrostatic pressure
.the pressure forces molecules like water and solutes out of the blood through pores in the capillary endothelium
.molecules move through basement membrane that acts as a filter preventing large molecules and blood from passing the bowman’s capsule
.molecules move through the bowman’s capsule epithelium which has specialised cells like podocytes which wrap around capillaries to filter the blood
.filtered fluid collects in bowman’s capsule

Question 15

what is the PCT

Answer 15

component of the nephron which is lined with epithelial cells

Question 16

adaptations of epithelial cells in PCT

Answer 16

microvilli- increase SA
basal infoldings - increase SA
.many mito
.co-transporters proteins

Question 17

reabsorption process at PCT

Answer 17

.Na+ are actively transported into blood capillaries reducing Na+ conc in epithelial cells

.Na+ moves from lumen into epithelial cells down the conc gradient

.Na+ is co-transported with glucose and amino acids into the epithelial cells

.these reabsorbed molecules diffuse into the blood capillaries

Question 18

what does the DCT do

Answer 18

makes final adjustments to the filtrate by reabsorbing salts and water

Question 19

reabsorption at the DCT process

Answer 19

.absorption of useful substances via active transport

.DCT membrane alters it permeability to regulate reabsorption of water and solutes

.can also regulate blood pH via reabsorbing certain ions

Question 20

descending limb of Henle permeability

Answer 20

permeable to water but not to ions

Question 21

ascending limb of Henle permeability

Answer 21

permeable to ions but not to water

Question 22

water reabsorption in the loop of Henle

Answer 22

.water leaves the the filtrate via osmosis from the descending limb to the interstitial space

.filtrate loses water as it moves down the limb reaching its lowest WP at the tip of the medulla

.the loss water is reabsorbed into blood in the surrounding capillaries via osmosis

.Na+ and Cl- diffuse out of the filtrate from the bottom of the ascending limb to the interstitial space due to low WP

.this concentrates ions in the interstitial space in the medulla = low WP

.Na+ and Cl- is actively transported out of the top of the ascending limb as WP increase

.this creates a WP in the interstitial space with the highest WP in the cortex and the lower WP deeper in the medulla

Question 23

how is the counter current multiplier set up