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Biology Module 5 > Excretion 5.2 > Flashcards

Excretion 5.2 Flashcards

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1
Q

why is excretion important?

A

important in maintaining metabolism

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2
Q

what is excretion?

A

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

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3
Q

give examples of excretory organs

A

lungs,kidney,liver and skin

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4
Q

what is metabolic waste made of?

A

carbon dioxide

nitrogenous waste

urea

water

salts

ammonia

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5
Q

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

A

fish- ammonia

birds and insects- uric acid

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6
Q

what is bile pigments?

A

breakdown of haemoglobin from old red blood cells in the liver

they colour the faeces

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7
Q

what is urea made of?

A

undigested food and fibre

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8
Q

how does the skin act as an excretory organ?

A

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

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9
Q

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

A

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

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10
Q

what is the role of the liver

A

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

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11
Q

what are hepatocytes?

A

liver cells

contains a nuclei, golgi apparatus, folded membrane and mitochondria

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12
Q

what is the difference between the hepatic artery and hepatic vein

A

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

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

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13
Q

describe the internal structure of the liver

A

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

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14
Q

function of the bile caniculli?

A

where bile is produced and secreted

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

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15
Q

why might blood in the hepatic portal vein contain toxins

A

after digestion of alcohol, blood from the intestine contains toxins

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16
Q

what are the functions of liver

A

storage of glycogen

detoxification

formation of urea

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17
Q

explain the role of the liver in storing glycogen

A

hepatocytes are involved in converting glucose into glycogen

glycogen can be broken down to release glucose into the blood

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18
Q

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

A

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

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19
Q

what happens when too much alcohol is taken

A

cirrhosis - when cells of the liver die and scar tissue blocks the flow of blood

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20
Q

explain how detoxification works on alcohol

A

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

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21
Q

what does NAD do

A

breakdown fatty acids used in respiration

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22
Q

what happens if NAD is used up

A

breakdown of fatty acids is no longer possible

FA converted back to lipids

builds up in liver and can cause hepatitis or cirrhosis

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23
Q

describe AA in the liver

A

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

24
Q

what is deamination

A

removal of an amino group from the amino acid leaving ammonia

25
Q

describe ammonia in the liver

A

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

26
Q

what are the products of deamination?

A

ammonia and keto acid

27
Q

function of kupffer cells

A

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

28
Q

what is the function of the hepatic portal vein

A

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

29
Q

what are the kidney tubules called

A

nephron

30
Q

what does the nephron consist of

A
  • bowman’s capsule
  • glomerulus
  • proximal and distal convoluted tubule
    -loop of henle
  • collecting duct
31
Q

what does the filter barrier consist of

A

endothelial and epithelial cells
basement membrane

32
Q

function of bowman’s capsule

A

contains the glomerulus and where ultrafiltration takes place

33
Q

function of glomerulus

A

knot of capillaries where pressure forces all the solutes in the blood plasma through capillary walls

34
Q

function of proximal convoluted tubule

A

the first coiled tubule where products in blood are reabsorbed

35
Q

function of loop of henle

A

long loop across the medulla and cortex, used to concentrate urine

36
Q

function of distal convoluted tubule

A

second coiled tubule, where osmosis and diffusion of solutes occur to maintain the water potential and ph of blood

37
Q

function of collecting duct

A

urine travels down it and ADh creates aquaporins to allow the exit of excess H2O

38
Q

function of endothelium cells of filter barrier

A

gaps, allow dissolved substances/ blood plasma to pass capillary

39
Q

function of basement membrane of filter barrier

A

prevents large molecules and proteins from entering

40
Q

function of epithelial cells of filter barrier

A

known as podocytes, have projection so there are gaps between cells to let blood pass through lumen of Bowman’s capsule

41
Q

what is ADH?

A

A hormone that helps blood vessels constrict and helps the kidneys control the amount of water and salt in the body. This helps control blood pressure and the amount of urine that is made.​

42
Q

what is ultrafiltration

A

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

43
Q

describe the process of ultrafiltration (6 marks)

A
  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​
44
Q

what is filtered out of the blood
?

A

Water​

Amino acids​

Glucose ​

Urea​

Inorganic mineral ions ( Na, K, Cl) ​

45
Q

what is selective reabsorption?

A

occurs because during ultrafiltration, important components of the blood are filtered out and they need to be reabsorbed into the body.

46
Q

describe the process of selective reabsorption (6 marks)

A
  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
47
Q

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

A

Cell surface membrane, highly folded to form microvilli – increases surface area for reabsorption ​

Cell surface membrane – contains cotransporter proteins, transport glucose/amino acid with sodium ions from tubule into cell​

Cytoplasm, lots of mitochondria to release ATP ​

48
Q

how is the water potential regulated in the kidney

A

When the water potential of the blood is too low
body is dehydrated more water reabsorbed by osmosis into blood -> therefore the urine is more concentrated, so less water is lost during excretion ​

When the water potential is too high (the body is too hydrated) so less water is reabsorbed by osmosis into the blood, so urine is lost during excretion​

49
Q

What is osmoregulation

A

the control of water potential in the blood​

detected by osmoreceptors in the hypothalamus​

stimulate the posterior pituitary gland to release more or less ADH when water potential decreases or increases​

50
Q

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

A

: Blood ADH levels rises when dehydrated​

Water content in blood drops and so does the water potential​

Detected by osmoreceptors in the hypothalamus ​

The posterior pituitary gland is stimulated to release more ADH into the blood​

DCT walls are more permeable, so more water is reabsorbed into the blood by osmosis​

a small amount of highly concentrated urine produced so less water lost​

: When blood ADH levels fall when hydrated, vice versa occurs​

51
Q

describe the countercurrent multiplier mechanism (6 marks)

A

top of the ascending limb
Na+ and Cl- ions are actively pumped out into the medulla
ascending limb = impermeable to water
so water stays inside tubule
creates a low water potential in the medulla because there’s a high concentration of urine ​

Because there is a low water potential in the medulla than the descending limb
water moves out of the descending limb by osmosis into the medulla
makes the filtrate more concentrated the water in the medulla is reabsorbed into the blood through the capillary network​

bottom of the ascending limb
Na+ and Cl- ions diffuse out of the medulla
further lowering the water potential in the medulla

first three stages increase the ion concentration in the medulla
lowers the water potential
causes water to move out of the collecting duct by osmosis
water in the medulla reabsorbed into the blood through the capillary network

52
Q

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

A

infections : causes inflammation, damages cells, interferes with ultrafiltration and reabsorption​

High blood pressure : damages the glomerulus, damages the capillaries so large molecules like proteins can enter the urine​

53
Q

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

A

.Waste products to build to build up, results in weight loss and vomiting​

. Anemia , lack of haemoglobin in the blood​

. Imbalance of electrolytes, like calcium and phosphate leads to brittle bones​

54
Q

what is renal dialysis?

A

when the patient’s blood is filtered

55
Q

describe haemodialysis (6 marks)

A

where the patient’s blood is passed through a dialysis machine.

blood flows to one side of a partially permeable membrane and dialysis fluid on the other side​

Waste products and excess water and ions diffuse across the membrane into dialysis fluid, removing them from the blood​

Blood cells and larger molecules are stopped from leaving the blood ​

Patients tend to feel sick after because waste products and fluid builds up in the blood

56
Q

what is a kidney transplant? ( 4 marks )

A

new kidney is implanted to a patient’s body to replace a damaged kidney.​

New kidney must have same blood and tissue type​

Cheaper and more efficient time wise than dialysis​

However risky because the body can reject the new organ

57
Q

what are steroids and what are the negatives?

A

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

Biology Module 5 (8 decks)

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