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OCR Biology > 5.2 EXCRETION > Flashcards

5.2 EXCRETION Flashcards

1
Q

Define excretion

A
  • the removal of metabolic waste from the body
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2
Q

State the three types of toxic metabolic waste

A
  • Carbon dioxide
  • Nitrogenous compounds
  • Bile pigment
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3
Q

What are liver cells called?

A
  • Hepatocytes
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4
Q

Draw the external and internal structure of the liver

A
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5
Q

What does the hepatic artery in the liver do?

A
  • Supply’s the liver with oxygenated blood from the heart
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6
Q

What does the hepatic vein in the liver do?

A
  • Take away deoxygenated blood from liver to the heart
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7
Q

What does the hepatic portal vein in the liver do?

A
  • Supply nutrient filled deoxygenated blood to the liver from the digestive system
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8
Q

Describe the contents of the bile duct in the liver

A
  • Contains bile which contains the bile pigment called bilirubin
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9
Q

State the two roles of kupffer cells

A
  • Act as macrophages to engulf foreign matter
  • Break down and recycle old red blood cells into bilirubin which is excreted in faeces
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10
Q

State the type of cell that produces bile

A
  • Hepatocytes
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11
Q

State two adaptations of hepatocytes

A
  • Dense cytoplasm
  • Many mitochondria
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12
Q

State the functions of the liver

A

1) Storage of glucose
2) Detoxification
3) Urea formation

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13
Q

Describe the process of storage of glucose in the liver

A
  • In response to insulin the hepatocytes start to absorb excess glucose and convert it into glycogen where its stored
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14
Q

Define detoxification

A
  • the breakdown of unwanted chemicals like drugs, alcohol, hormones and toxins
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15
Q

Draw the process of detoxification of alcohol in the liver

A
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16
Q

State what acetyl coenzyme A is used for

A
  • Respiration
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17
Q

State the two steps of urea formation in the liver

A

1) Deamination
2) Ornothine cycle

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18
Q

Describe the two steps of urea formation in the liver

A
  • Deamination forms ammonia and keto acid from an amino acid and oxygen
  • Ornothine cycle forms urea and water from ammonia and carbon dioxide
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19
Q

Draw the external structure of the kidneys

A
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20
Q

State the role of the renal artery and renal vein in the kidneys

A
  • Renal artery provides oxygenated blood
  • Renal vein takes away deoxygenated blood
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21
Q

Draw the structure of a nephron in the kidneys

A
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22
Q

State the three functions of the kidneys

A
  • Ultrafiltration
  • Selective re-absorbtion
  • Formation of urine
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23
Q

State where ultrafiltration occurs in the nephron

A
  • Bowmans capsule
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24
Q

State where selective re-absorbtion occurs in the nephron

A
  • Proximal convoluted tubule
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25
Q

State where formation of urine occurs in the nephron

A
  • Collecting duct
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26
Q

State why the afferent arteriole is wider than the efferent arteriole

A
  • The create a hydrostatic pressure gradient between the glomerulus and bowmans capsule so ultrafiltration happens
27
Q

State the three layers of filter substances must go between the glomerulus and bowmans capsule

A
  • Capillary endothelium (has gaps)
  • Basement membrane
  • Bowmans capsule podocyte epithelial cells (hair like projections)
28
Q

State the five things that are filtered out the glomerulus during ultrafiltration

A
  • Water
  • Amino acids
  • Mineral ions
  • Glucose
  • Urea
29
Q

State the two things than remain in the capillaries during ultrafiltration

A
  • Proteins
  • Erythrocytes
30
Q

Describe the process of selective re-absorbtion in the kidneys

A

1) Sodium ions are actively pumped out of cells lining the tubule and into the blood plasma
2) Concentration of sodium ions in cytoplasm decreases, forming a concentration gradient
3) Sodium ions diffuse into cells lining the tubule via co-transporter proteins so carry a glucose or amino acid with them
4) Glucose and amino acids diffuse from cell lining tubule into the blood plasma

31
Q

State four ways the cells lining the proximal convoluted tubule is specialised for selective re-absorbtion

A

1) Highly folded plasma cell surface membranes to increase surface area for absorbtion
2) Plasma cell surface membrane contains cotransport proteins
3)

32
Q

State where water is reabsorbed in the nephron

A
  • Loop of henlee
33
Q

Draw a diagram of water reabsorbtion at the loop of henlee

34
Q

Define osmoregulation

A
  • The control of water potential in the body
35
Q

State the usefulness of osmoregulation

A
  • So excess water doesn’t enter cells and cause lysis
  • So excess water doesn’t leave cells
36
Q

Describe the urine produced by kidneys when water is abundant in the body

A
  • Large volumes
  • Dilute urine
37
Q

Describe the urine produced by kidneys when water is absent in the body

A
  • Low volumes
  • Concentrated
38
Q

Describe the state of the collecting ducts when water is abundant in the body

A
  • Collecting duct walls become less permeable so that less water is reabsorbed into the bloodstream as is not needed
  • Higher volume of urine produced
39
Q

Describe the state of the collecting ducts when water is absent in the body

A
  • Collecting duct walls become more permeable so that more water is reabsorbed into the bloodstream as it’s needed
  • Lower volume of urine produced
40
Q

State the role of ADH

A
  • Controls the permeability of the collecting duct
  • When released into the bloodstream, the collecting duct walls become more permeable so more water is re-absorbed back into the blood
41
Q

Describe the response to ADH release into the bloodstream

A
  • ADH binds to specific receptors of cells of collecting wall duct
  • Cause a chain of enzyme-controlled reactions
  • Results in vessels containing aquaporins to fuse with the plasma membrane
  • More water is reabsorbed into the blood
  • Less volume urine with a low water potential produced (more solute concentrated)
42
Q

Describe the response to ADH NOT release into the bloodstream

A

1) There is low ADH so the plasma cell surface membrane begins to fold inwards in order to remove the aquaporins from the membrane
2) This reduces the permeability of the collecting duct walls
3) Less water is reabsorbed into the blood
4) More water passes down the collecting duct
5) Higher volume with a high water potential urine produced

43
Q

Define osmo-receptor

A
  • A sensory receptor in the hypothalamus that detects changes in water potential
44
Q

Explain how osmo-receptors control water potential in terms of negative feedback

A

1) When water potential is low (negative) the osmo-receptor cells loose water by osmosis and shrink as a result
2) Therefore ADH is released into the bloodstream to make collecting duct walls more permeable
3) Thus, wtaer potenial increases back to the norm/optimum

45
Q

Define kidney failure

A
  • When the kidneys cannot osmoregulate or filter waste products (urea) out of the blood
46
Q

State the two ways of assesing kidney failure

A

1) Glomerular filtration rate (GFR)
2) Analysing urea for proteins

47
Q

Define and explain glomerular filtration rate (GFR)

A
  • The rate at which fluid enters the nephrons (per minute)
  • Normal range is between 90-120 cm³ min⁻¹
48
Q

Explain what having proteins in the urine indicates

A
  • Indicates that filtration mechanism is damaged
  • (Kidney failure)
49
Q

State four causes of kidney failure

A

1) Diabetes (T1 and T2)
2) Heart disease
3) Hypertension
4) Infection

50
Q

Define renal dialysis

A
  • Machine used to artificially regulate concentrations of solutes in the blood
51
Q

State the two treatments for kidney failure

A

1) Renal dialysis
2) Kidney transplant

52
Q

State the two types of renal dialysis

A

1) Haemodialysis
2) Peritoneal dialysis

53
Q

Explain how renal dialysis works to regulate solute concentrations

A

1) Waste products, excess fluids and mineral ions are moved out the blood by passing it over a partially permeable dialysis machine that allows exchange of substances between blood and dialysis fluid
2) The dialysis fluid contains the correct concentrations of substances found in the blood plasma
3) Any substance in excess in the blood diffuses across the membrane into the dialysis fluid
4) Any substance in low concentrations diffuse from the dialysis machine into the blood

54
Q

Explain haemodialysis

A
  • Blood for artery or vein is passed into an artifical dialysis membrane shaped to form many artificial capillaries which increases surface area for exchange
  • Heparin is added to prevent clotting
  • Artificial capillaries are surrounded by dialysis fluid which flows in a countercurrent direction to improve efficiency of exchange
55
Q

Explain peritoneal dialysis

A
  • The dialysis membrane is the persons own abdominal membrane (living cells)
  • The dialysis fluid is inserted directly into the gaps between the abdominal walls and organs
  • Dialysis fluid is drained afterwards
  • (Requires a healthy diet)
56
Q

Define immunosuppressant drug

A
  • Prevents the immune system from recognising a new organ as foreign, so the body doesnt reject it
57
Q

State four advantages of a kidney transplant

A

1) Doesnt require repeated dialysis
2) Their diet is less limited
3) Better quality of life
4) No longer chronically ill

58
Q

State three disadvantages of a kidney transplant

A

1) Require longterm immunosuppressent drugs
2) Risk of rejection/surgery
3) Difficulty finding a donor

59
Q

Describe urine testing

A
  • Tests for small molecules in the urine not reabsorbed into the nephron
60
Q

State and describe five uses of urine testing

A

1) Glucose for the diagnosis of diabetes
2) Alcohol to determine blood alcohol levels
3) Recreational drugs
4) hCG in pregnancy testing
5) Anabolic steroids

61
Q

State why monoclonal antibodies are used in pregnancy testing

A
  • Because they are specific to one complementary molecule
62
Q

Describe the steps of pregnancy testing

A

1) Urine in poured onto the stick
2) hCG binds to mobile antibodies that are attached to a blue head
3) Mobile antibodies move down the test stick
4) If hCG is present, it binds to the fixed antibodies and forms a blue line
5) Mobile antibodies with no hCG attached bind to another fixed site to prove the test is working

63
Q

State why hCG is able to be detected in the urine

A
  • It has a molar mass of less than 69,000

OCR Biology (27 decks)

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