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Alevel Biology OCR A > 5.1.2 Excretion COMPLETE > Flashcards

5.1.2 Excretion COMPLETE Flashcards

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1
Q

DEFINITION- Excretion

A

The removal of the waste products of metabolism from the body.

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2
Q

CO2 Transport

A
  1. CARBONIC ACID- Water and CO2 converted by carbonic anhydrase. Then dissociates into H+ and HCO3-
  2. CO2 also dissolves into the plasma forming carbonic acid
  3. CO2 also directly binds to haemoglobin forming CARBAMINOHAEMOGLOBIN
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3
Q

Effect of increasing CO2

A

Increased CO2 leads to more H+ ions increasing acidity. Proteins act as a buffer taking up H ions.
Medulla Oblongata detects increase in H ions and increases breathing rate.

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4
Q

Respiratory Acidosis

A

Medical Condition in which decreased ventilation causes increased blood CO2 conc. and decreased pH.
Caused by asthma, blockages of the airways and emphysema.

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5
Q

Functions of the Liver

A

CONTROL- blood sugar, lipids and amino acids
SYNTHESIS- plasma proteins, cholesterol, bile
STORAGE- vitamins A/D/B12, from, glycogen
DETOXIFICATION- Alcohol, Drugs
BREAKDOWN- Old RBC, hormones

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6
Q

Hepatic Artery

A

Moves from the Aorta to Liver, blood contains O2 for aerobic respiration.

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7
Q

Hepatic Portal Vein

A

From the small intestine to the liver, blood contains amino acids and glucose. Not connected to the heart

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8
Q

Hepatic Vein

A

From the liver to the vena cava, blood contains CO2 and waste products of respiration.

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9
Q

Bile Duct

A

From the liver to the gallbladder, containing the bile produced by hepatocytes

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10
Q

Liver Lobules

A

The lobule is formed by many hepatocytes
Branches of the hepatic artery and portal vein carry blood betweens rows and are called SINUSOIDS
The central vein is a branch of the hepatic vein.
Channels carry bile are called BILE CANALICULUS
KUPFFER CELLS line the sinusoids

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11
Q

Hepatocyte Structure

A

Lots of organelles such as mitochondria and ribosomes
Glycogen granules and fat droplets
Microvilli to increase SA

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12
Q

Kupffer Cell Structure

A

Specialised macrophages, engulf bacteria and breakdown RBC, product of the breakdown includes Bilirubin

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13
Q

Formation of Urea

A
  1. Deamination

2. The Ornithine Cycle

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14
Q

Deamination

A

Excess amino acids can’t be stored
The amino group is removed to form ammonia.
Keto Acids remain or their converted into fats for storage

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15
Q

The Ornithine Cycle

A

Produces urea from ammonia, as urea is less toxic and less soluble.
Dissolves in plasma to be excreted by kidneys
Uses ATP and CO2, takes place in the mitochondria

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16
Q

DEFINITION- Detoxification

A

Conversion of toxic molecules to less toxic molecules, e.g. catalase breaks down hydrogen peroxide into water and oxygen

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17
Q

Ethanol

A

A drug that depresses nerve activity, small lipid molecules that cross the plasma membrane via simple diffusion. Enters bloodstream quickly and is toxic

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18
Q

Detoxification of Alcohol

A

Broken down in the hepatocytes
Ethanol-> Ethanal (ethanol dehydrogenase)
Ethanal-> Ethanoate (ethanal dehydrogenase)
2H atoms are removed and combine with coenzyme NAD

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19
Q

Problem with alcohol and fatty acids

A

If too much alcohol theres not enough NAD to breakdown the fatty acids, so they’re converted back to lipids and stored in hepatocytes.

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20
Q

Liver disease

A

Scarring of the liver cells causing cell damage and liver failure.

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21
Q

Role of the Kidney

A

Remove waste products from the blood to produce urine, carried out by the nephrons

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22
Q

Nephrons

A

Blood enters through the renal artery, which branches into tiny arterioles called AFFERENT Arterioles and enter renal capsule. They divide into a complex called the GLOMERULUS. These merge into the EFFERENT arteriole which eventually become the Renal Vein

23
Q

Ultrafiltration

A

The filtration on a micro scale, small molecules are filtered out of the blood and into the lumen of the nephron.

24
Q

Adaptions for Ultrafiltration

A

BASEMENT MEMBRANE- acts as a filter, however blood cells and proteins are too big
DIAMETER OF BLOOD VESSELS- The Afferent arteriole has a wider diameter. Builds up hydrostatic pressure
PODOCYTES- Specialised cells with fingerlike projections that allow filtrate to pass beneath cells
CAPILLARY ENDOTHELIUM- Spaces between cells that fluid passes between

25
Q

Filtrate Composition

A

Same as plasma, except for larger plasma protein that can’t cross the basement membrane

26
Q

DEFINITION- Selective Reabsorption

A

Parts of the filtrate are reabsorbed into the blood i.e. glucose, amino acids

27
Q

Proximal Convoluted Tubule Cells Structure

A

Cuboidal epithelial cells with microvilli to increase SA
Lots of mitochondria to provide ATP
Blood capillaries lie close to the surface

28
Q

Selective Reabsorption Process

A
  1. Na-K pumps actively transport sodium out of PCT cells
  2. A low conc. leads leads to NA ions entering by facilitated diffusion, glucose and amino acids cotransported with NA
  3. This increases the filtrates water potential
  4. Water moves down gradient by osmosis
  5. Urea enters PCT by simple diffusion
  6. Any large molecules e.g. proteins, reabsorbed by endocytosis
29
Q

Reabsorption of Water

A

Water is reabsorbed in via the loop of henle

30
Q

Loop of Henle

A

Reabsorbs water from collecting duct
Lowers water potential in the medulla
Shorter in aquatic animals

31
Q

Descending limb

A

Narrow
Thin walls
Highly water permeable

32
Q

Ascending limb

A

Wider
Thick walls
Impermeable to water

33
Q

Water reabsorption process

A
  1. Na and Cl actively transported out the ascending limb
  2. Water can’t leave ascending limb
  3. Water leaves descending limb by osmosis
  4. Lowest water potential in deepest part of medulla
  5. Na and Cl diffuse out ascending limb
  6. Water gradient develops
  7. Collecting duct is permeable to water
  8. Water potential in the interstitial region is lowered
34
Q

Distal Convoluted Tubule

A

Contains microvilli and mitochondria

The region controls pH, salts under the influence of hormones

35
Q

Collecting Duct

A

The tubule fluid contains a lot water
As the tubule fluid passes down the collecting duct, water moves by osmosis into the surrounding medulla where theres a lower water potential, It then enters blood capillaries by osmosis

36
Q

Desert Mammal Adaptions

A 
Long loop of Henles 
Oxidise fats rather than carbohydrates 
Long colon (large intestine) 
Less sweating 
Produce dry faeces
37
Q

Osmoregulation

A

The control of water and salt levels in the body

Involves kidney, pituitary gland, hypothalamus

38
Q

How water is gained

A

Food
Respiration
Drinking water

39
Q

How water is lost

A

Urine
Sweat
Faeces
Water vapour

40
Q

Osmoreceptors

A

Found in the hypothalamus and monitors blood passing through, they’re sensitive to water potential
Low water potential leads to cell shrinkage as water moves out

41
Q

Neurosecretory

A

Produce a hormone called Anti Diuretic Hormone
Produced in the cell Bodies and its secreted into axons, these terminate in the posterior pituitary gland
When stimulated an action potential is sent down axons, ADH is secreted in the posterior pituitary gland
Target cells are in the Collecting duct

42
Q

How ADH affects the permeability of the Collecting duct

A

ADH molecules combine with receptors on the membrane of the collecting duct
Activates an enzyme which causes vesicles in the cells to fuse with cell surface membrane (Adenylyl cyclase)
Vesicles contain Aquaporins making membrane more permeable
More water leaves the collecting duct by osmosis
When less ADH, membrane folds inwards to reform vesicles

43
Q

Aquaporins

A

The channel’s very narrow so large molecules struggle

A positive charge in the centre will repel positive ions

44
Q

Kidney Failure Causes

A

Caused by high blood pressure, diabetes, infection

45
Q

Glomerular Filtration Rate

A

Estimate of how much fluid passes into nephrons each minute

Protein in urine also indicates if filtration mechanisms are damaged

46
Q

Kidney Failure Treatment

A

DIALYSIS
Waste products, excess fluid, mineral ions are removed from blood by passing it over a partially permeable dialysis membrane.
Substances are exchanged between the fluids
The dialysis fluid contains the correct concentrations

47
Q

Types of Dialysis

A

Haemodialysis

Peritoneal dialysis

48
Q

Haemodialysis

A

Blood from an artery or vein is passed into a machine containing an artificial dialysis membrane, special shape to increase SA
Heparin is added to avoid clotting
Dialysis fluid flows in the opposite direction
Must be performed in a clinic 3/4 times a week for 3 hours

49
Q

Peritoneal Dialysis

A

The dialysis membrane is inside the body’s abdominal membrane
First a surgeon implants a permanent tube into the abdomen
Dialysis solution fills the space then after several hours its drained
This can be done by the patient at home and they can move around

50
Q

Kidney Transplant

A

Surgery where a new organ is implanted in the lower abdomen

Immunosuppressant drugs are needed to prevent rejection

51
Q

Advantages of kidney transplant

A

Freedom form time consuming dialysis
Feel physically fitter
Improved quality of life- can travel

52
Q

Disadvantages of Kidney transplant

A

Need to take immunosuppressant drugs
Major surgery is needed
Need regular checkups to looks for signs of rejection
Side effects of immunosuppressants:
Fluid retention, high blood pressure, become susceptible to infection

53
Q

Pregnancy Testing

A

Pregnant women produce the hormone HCG in the placenta
Mobile monoclonal antibodies attach the HCG, have a blue pigment
This moves down the stick with HCG acting as an antigen due to its complementary shape
HCG then binds to the immobilised antibodies and a blue line forms
Left over monoclonal antibodies continue to another fixing site producing a control line

54
Q

Anabolic Steroids

A

Stimulate the development and growth of tissues such as muscle
Used as a performance enhancer to increase muscle mass

Alevel Biology OCR A (26 decks)

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