Excretion 5.2

Question 1

why is excretion important?

Answer 1

important in maintaining metabolism

Question 2

what is excretion?

Answer 2

process by which excess toxic waste products of metabolism are removed from the body

Question 3

give examples of excretory organs

Answer 3

lungs,kidney,liver and skin

Question 4

what is metabolic waste made of?

Answer 4

carbon dioxide

nitrogenous waste

urea

water

salts

ammonia

Question 5

mammals produce urea, fish and birds/insects produce..?

Answer 5

fish- ammonia

birds and insects- uric acid

Question 6

what is bile pigments?

Answer 6

breakdown of haemoglobin from old red blood cells in the liver

they colour the faeces

Question 7

what is urea made of?

Answer 7

undigested food and fibre

Question 8

how does the skin act as an excretory organ?

Answer 8

sweat contains salts, urea, water, uric acid and ammonia

Question 9

what happens if products of metabolism build up in the body?

Answer 9

build up of CO2 and NH3 is toxic

this can interfere by altering the pH or act as inhibitors and reduce the activity of enzymes

Question 10

what is the role of the liver

Answer 10

breakdown of unwanted or toxic substances and the production of excretory waste,

Question 11

what are hepatocytes?

Answer 11

liver cells

contains a nuclei, golgi apparatus, folded membrane and mitochondria

Question 12

what is the difference between the hepatic artery and hepatic portal vein

Answer 12

hepatic a - receives oxygenated blood from the heart ( smaller than v bcs carries only 30% blood)

hepatic portal v - brings deoxygenated blood back to heart (bigger bcs carries 70%)

Question 13

describe the internal structure of the liver

Answer 13

. hepatocytes
. lobes -> lobules (connective tissue)
. sinusoids ( wide capillaries)
. branch of hepatic vein ( drains blood away from lobule)
. kupffer cells
. bile caniculli

Question 14

function of the bile caniculli?

Answer 14

where bile is produced and secreted

drains it into the bile duct which then brings it to the gall bladder to be stored

Question 15

why might blood in the hepatic portal vein contain toxins

Answer 15

after digestion of alcohol, blood from the intestine contains toxins

Question 16

what are the functions of liver

Answer 16

storage of glycogen

detoxification

formation of urea

Question 17

explain the role of the liver in storing glycogen

Answer 17

hepatocytes are involved in converting glucose into glycogen

glycogen can be broken down to release glucose into the blood

Question 18

explain how detoxification works on hydrogen peroxide (substance in the liver)

Answer 18

catalase breaks down hydrogen peroxide into oxygen and water (by-product)

Question 19

what happens when too much alcohol is taken

Answer 19

cirrhosis

Question 20

explain how detoxification works on alcohol

Answer 20

ethanol, broken down by hepatocytes into ethanal then to acetic acid which is less harmful

Question 21

what does NAD do

Answer 21

breakdown fatty acids used in respiration

Question 22

what happens if NAD is used up

Answer 22

breakdown of fatty acids is no longer possible

FA converted back to lipids

builds up in liver and can cause hepatitis or cirrhosis

Question 23

describe AA in the liver

Answer 23

excess amino acids cant be stored in the body as their amino group make them toxic

they cant also be excreted as a whole because theyre full of lots of energy

so, excreted via deamination

Question 24

what is deamination

Answer 24

removal of an amino group from the amino acid leaving ammonia

Question 25

describe ammonia in the liver

Answer 25

very toxic and insoluble , quickly converted in to urea which is less soluble and less toxic

Question 26

what are the products of deamination?

Answer 26

ammonia and keto acid

Question 27

function of kupffer cells

Answer 27

attached to the walls of the sinusoids, remove bacteria and break down old RBC​

Question 28

what is the function of the hepatic portal vein

Answer 28

brings products of digestion from small intestine to liver so that any harmful substances can be filtered out and destroyed before digestion

Question 29

what are the kidney tubules called

Answer 29

nephron

Question 30

what does the nephron consist of

Answer 30

- bowman's capsule - glomerulus - proximal and distal convoluted tubule -loop of henle - collecting duct

Question 31

what does the filter barrier consist of

Answer 31

endothelial and epithelial cells basement membrane

Question 32

function of bowman's capsule

Answer 32

contains the glomerulus and where ultrafiltration takes place

Question 33

function of glomerulus

Answer 33

knot of capillaries where pressure forces all the solutes in the blood plasma to the Bowman's capsule

Question 34

function of endothelium cells of filter barrier

Answer 34

gaps, allow dissolved substances/ blood plasma to pass capillary

Question 35

function of basement membrane of filter barrier

Answer 35

prevents large molecules and proteins from entering

Question 36

function of epithelial cells of filter barrier

Answer 36

podocytes, gaps between cells to let blood pass through lumen of Bowman's capsule

Question 37

what is ADH?

Answer 37

hormone constricts blood vessles helps the kidneys control the amount of water and salt in the body

Question 38

what is ultrafiltration

Answer 38

the process of filtration of blood from the glomerulus into the Bowman's capsule because of increased glomerular blood pressure

Question 39

describe the process of ultrafiltration (6 marks)

Answer 39

1. Blood flows into glomerulus through the afferent arteriole, that carries the blood away​ 2. The afferent arteriole is wider than the efferent arteriole ​ 3. The difference in diameter ensure that blood in the capillaries of glomerulus maintains a pressure higher than the Bowman's capsule​ 4. This pressure difference pushes fluid from the blood into the Bowman's capsule​

Question 40

what is filtered out of the blood ?

Answer 40

Water​ Amino acids​ Glucose ​ Urea​ Ions

Question 41

describe the process of selective reabsorption (6 marks)

Answer 41

1. Na+ ions are pumped out of the cells actively 2. conc. of Na+ ions in cytoplasm decreases creating a concentration gradient 3. Na+ ions diffuse into cell through a cotransport protein - carrying glucose or an AA at the same time 4. Water moves into cell by osmosis 5. Glucose/AA diffuse into blood

Question 42

how are the cells needed in reabsorption specialised? (4 marks)

Answer 42

microvilli – increases surface area for reabsorption Cytoplasm, lots of mitochondria to release ATP ​

Question 43

What is osmoregulation

Answer 43

the control of water potential in the blood​

Question 44

how does ADH change the water content of the blood when it is too low or high?

Answer 44

: Blood ADH levels rises when dehydrated​ water potential​drops Detected by osmoreceptors in the hypothalamus ​ The posterior pituitary gland is stimulated to release ADH into the blood​ DCT walls and collecting duct walls are more permeable, so more water is reabsorbed into the blood by osmosis​ highly concentrated urine produced so less water lost​ : When blood ADH levels fall when hydrated, vice versa occurs​

Question 45

state 2 things that lead to kidney failure (4 marks)

Answer 45

infections high blood pressure

Question 46

describe what could happen to the body due to kidney failure 3 things

Answer 46

.Waste products to build up - weight loss and vomiting​ . Anemia . Imbalance of electrolytes - brittle bones​

Question 47

what is renal dialysis?

Answer 47

when the patient's blood is filtered

Question 48

what is a kidney transplant? ( 4 marks )

Answer 48

new kidney to replace damaged kidney.​ New kidney must have same blood and tissue type​ Y: cheaper than dialysis​ N: organ rejection

Question 49

what are steroids and what are the negatives?

Answer 49

Anabolic steroids are drugs that builds up muscle tissue​ Athletes are banned from taking these, as it is unfair and has dangerous side effects like liver damage