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A-level Biology (Edexcel Salters) > Topic 1 > Flashcards

Topic 1 Flashcards

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1
Q

What is cardiovascular disease?

A

Diseases of the heart and circulation

Main forms are:

  • Conorary heart disease
  • Stroke
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2
Q

Open circulatory systems

A
  • Occurs in insects and other animal groups
  • Blood circulates in a large open space
  • Heart pumps blood into cavities surrounding organs
  • Substances diffuse between blood and cells
  • When heart relaxes, blood is drawn back from the cavities through small, valved, opening into the heart
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3
Q

Closed circulatory systems

A
  • Occurs in all vertebrates
  • Blood enclose in blood vessels
  • High pressure as blood is forced along narrow tubes​
    • Blood travles faster, so more efficient at delivering substances
  1. Blood leaves heart through arteries, into aterioles, then through capillaries.
  2. Then back to the heart through venules to the veins
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4
Q

What is mass flow?

A

The movement of a fluid in one direction due to a difference in pressure, usually through a system of tube-like vessels.

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5
Q

What is the transport medium in animals?

A

Blood

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6
Q

Why is water a polar molecule?

A

It has an unevenly distriubted electrical charge

  • The hydrogen end is slightly postive, as the 2 hydrogens are pushed towards eachother
  • The oxygen end is slightly negetive, as the electons are more concentrated
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7
Q

Why is water dipole?

A

It has both negetive and postive charges

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8
Q

Explain hydrogen bonding in water molecules.

A
  • Slightly positively charged ends are attracted to slightly negetive ends of other water molecules.
    • Holds holds the water molecules together
      • It is liquid at room temperature
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9
Q

Why do many chemicals dissolve easily in water?

A

Water is dipole

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10
Q

Similarties of the structue of arteries and veins

A
  • Walls are made of collagen
    • tough fibrous protein
      • strong and durable
  • Contain elastin fibres
    • strech and recoil
  • Smooth muscle cells
    • constrict and dilate
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11
Q

Differences in the structure of arteries and veins

A

Arteries

Veins

Narrow lumen

Wide lumen

Thick walls

Thin walls

More collagen, smooth muscle and elastic fibres

Less collagen, smooth muscle and elastic fibres

No valves

Valves

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12
Q

What is it called when the heart constricts?

A

Systole

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13
Q

What is it called when the heart relaxes?

A

Diastole

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14
Q

What is a pulse?

A

The pulsing flow of blood in arteries passing over a bone close to the skin

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15
Q

Why does blood slow down in capillaries?

A

Narrow lumens cause more friction

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16
Q

What assists the flow of blood through veins?

A

Contraction of skeletal muscles during movement of limbs and breathing

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17
Q

Explain the cardiac cycle

A

Artial systole

  1. Blood returns to heart due to skeletal muslce as you move and breathe
  2. Blood under low pressure flows trhough the pumonary vein and vena cava into the left and right atria.
  3. As atria fill the AV valves open as pressure against them increases
  4. Blood flows into ventricles

Ventricular diastole

  1. Ventricles contract from base upwards
    • increases pressure
  2. pressure forces open semilunar valves
  3. Blood goes out through pulmonary arteries and aorta.
  4. Pressure of blood against AV valves closes them

Cardiac diastole

  1. Atria and ventrciles contract
  2. Elastic recoil of relaxing walls lowers the pressure
  3. Blood under high pressure in the arteries is drawn back towards the ventricles closing the semilunar valves
  4. Conorary arteries fill
  5. Low pressure in atria draws blood into heart
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18
Q

What is atherosclerosis?

A

Fatty diposists either block an artery or increase the chance of thrombosis.

  • Leads to conorary heart disease and strokes
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19
Q

What happens if atherosclerosis occurs in the coronary arteries?

A

Results in heart attack (myocardial infarction)

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20
Q

What happens if atherosclerosis occurs in the arteries supplying the brain?

A

Results in a stroke

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21
Q

What are platelets?

A

A type of blood cell without a nucleus

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22
Q

What is the process of atherosclerosis?

A
  1. The endothelium is damaged and dysfunctional
    • can be a result of high blood pressure or toxins from cigarette smoke
  2. Causes an inflammatory response
    • white blood cells leave blood vessel and move to artery wall
    • chemicals accumulate from blood, especially cholesterol
    • fatty deposit builds up, atheroma
  3. Calcium salts and fibrous tissue build up
    • results in hard swelling called plaque
    • artery wall loses some elasticity, it hardens
  4. Plaque narrows the lumen
    • more difficult to pump blood, increases blood pressure
    • dangerous postive feedback
    • becaause of increasing pressure even more plaque is more likely to form
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23
Q

What is the process of blood clotting?

A
  1. Platlets stick to damaged wall and to each other, forming a platlet plug
    • platelets change their shape from flattened disks to long thin projections.
  2. Thromboplastin, released from damaged tissue and platelets, catalyses the enzyme that changes the soluble prothrombin into thrombin
    • Ca2+ and vitamin K from the plasma also have to be present
    • triggers clotting cascade:
  3. Thrombin catalyses soluble fibrinogen to change into the insoluble fibrin which creates a mesh
  4. Fibrin mesh traps red blood cells, forming a clot
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24
Q

How does blood clotting occur?

A

Usually the arteries are too smooth and substances repel platlets so platlets don’t stick to the endothelium.

However, if there is atherosclerosis, the endothelium is damaged and platlets contact with the damaged tissue and exposed collagen. Clotting cascade is triggered

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25
Q

What is angina?

A

Chest pain

  • Could be a result of narrowing coronary arteries
  • Usually occurs when cardiac muscle is woking hard so needs to respire more.
26
Q

Atherosclerosis and Coronary Heart Disease

A
  • Narrow coronary arteries limits oxygen-rich blood supple to heart
  • Results in angina
  • Heart is forced to respire anaerobically
  • Causes chemical changes which trigger pain
  • Symptoms ease with rest
  • If fatty plaque in coronary arteries ruptures, collagen is exposed
  • Leads to rapid clot formation
  • Blood supply may be completely blocked
  • Heart msucle doesn’t receive blood so is ischaemic (without blood)
  • If this happens for long, muslce cells will be permeantly damaged
  • This is a heart attack or myocardial infarction
27
Q

Atherosclerosis and Stroke

A

If supply of blood to brain is briefly interrupted then a mini-stroke will occur

  • Same symptoms as a full stroke
  • Effects don’t last as long

If a blood clot bloacks an artery leading to the brain a full stroke will occur

  • If brain cells are oxygen deprevied for more than a few minutes, damage will be permeant and can be fatal
28
Q

What is an aneurysm?

A
  • If an artery narrows and becomes less flexible, blood can build behind
  • Artery then bulges as it fills with blood
29
Q

Define risk.

A

The probability of occurence of some unwanted event or outcome

30
Q

Why will people overestimate risks?

A

If the risk is :

  • involuntary (out of their control)
  • not natural
  • unfamiliar
  • dreaded
  • unfair
  • very small
    *
31
Q

What is a Cohort study?

A

A study that follows a large group of people over time to see who develops the disease.

  • Prospective - none of the participants have the disease at start
  • Used to identify risk factors
  • Can be very expensive
32
Q

What is hypertension?

A

Elevated blood pressure

  • One of most common factors in the development of CVD
33
Q

What is blood pressure?

A

A meassure of hydrostatic force of clood against walls of a blood vessel

34
Q

When is pressure in the arteries highest?

A

When the ventricles have contracted, this is systolic pressure.

35
Q

When is pressure in the arteries the lowest?

A

When the ventricles are relaxed, this is the diastolic pressure

36
Q

When is systolic pressure measured?

A

When the blood first starts the spurt through the artery that has been closed.

Its the highest reading

37
Q

When is diastolic pressure measured?

A

When the pressure falls to the point where no sound can be heard.

Its the lowest reading.

38
Q

What are the SI units for pressure?

A

Kilopascals

39
Q

What are the units in medical practice for pressure?

A

Millimetres of mercury, mmHG

  • The number of millimetres the pressure will raise a column of mercury
40
Q

What is periphedal resistance?

A

The contact between the blood and walls of the blood vessel causes friction.

41
Q

What is oedema?

A

Fluid building up in tissues and causing swelling, associated with kidney or liver disease, or resistriced body movement.

  • At atrial end of capillaries, blood is under pressure
  • This forces fluid and small molecules in plasma through tiny gaps between cells of the wall into intercellular space
  • This is tissue fluid / interstitial fluid
  • Blood cells and larger plasma porteins stay inside capillaries
  • Tissue fluid drains into network of lymph capillaries whoch returns fluid to blood via lymph vessel which empties into vena cava
  • Oedema occurs when pressure is too high so more fluid is pushed out so it accumulates within tissue
42
Q

What is a hyrdolysis reaction?

A

Addition of water to split a molecule by brekaing the glycosidic bond

43
Q

What is a glycosidic bond?

A

Bond that joins two sugar units together

44
Q

What are carbohydrates made up of?

A

Carbon, hydrogen and oxygen

45
Q

What monomers form to make starch?

A

Amylose and amylopectin

46
Q

What is starch?

A

Starch is a polysaccharide

  • insoluble
  • compact
  • found ONLY in plant cells
  • stores glucose
47
Q

What is Cellulose?

A

Cellulose is a polysaccharide

  • polymer of glucose
  • weak hyrogen bonds cause molecule to be long and staight
  • several cellulose molecules lie side by side to form microfibrils
    • microfibrils strengthen plant cell walls
  • found ONLY in plant cells
48
Q

Glucose + Glucose → ?

A

Glucose + Glucose → Maltose + Water

49
Q

Glucose + Fructose → ?

A

Glucose + Fructose → Sucrose + Water

50
Q

What reaction occurs when two monosaccharides join to make a disaccharide?

A

Condensation reaction

51
Q

Draw an alpha glucose molecule

A
52
Q

Draw a beta glucose molecule

A
53
Q

What is a lipid?

A

OIls and fats

54
Q

What’s a triglycerides?

A

A group of lipids that consist of 1 molecule of glycerol with 3 fatty acids attached to it

55
Q

What is a fatty acid molecule?

A

Long chain of carbon atoms with an acidic group (-COOH) at one end.

Hydrogens are attached to the carbons.

56
Q

What are phospholipids?

A

Like triglycerides but instead of 3 fatty acid chains, there are 2 fatty acid chains and a phospate gorup

  • Cell membranes have a double layer of phospholipids
57
Q

What happens when monosccharides are eaten?

A

They are rapidly absorbed into blood causing a sharp rise in blood sugar.

58
Q

Why does eating complex carbohydrates not cause drastic swings in blood sugar levels?

A

Polysccharides and disaccharides (complex carbohydrates) have to be digested into monosccharides before being absorbed, which takes time, so monosccharides are released more slowly

59
Q

How do you make lactose free milk?

A

Hydrolyse the lactose in milk to converts the diasccharide lactose into the monosccharides glucose and galactose.

  • The enzyme lactase is immobilised in a gel then made into beads
  • Milk is poured in a continous stream through a column conatining beads
60
Q

What are the three main polysccharides found in food?

A

Starch, cellulose (in plants) and glycogen (in animals)

  • Polymers of glucose
  • Sparingly soluble (don’t dissolve easily)
  • Don’t taste sweet
61
Q

Why are starch and glycogen good energy storage molecules?

A
  • Compact molecules with low solubility in water.
  • So dont effect concentration of water in cytoplasm
  • So don’t effect movement of water into or out of cell via osmosis
  • Don’t diffuse accros cell membranes
62
Q

What is starch made up of?

A

Amylose

  • Straight chain of between 200 and 5000 glucose molecules
  • 1, 4 glycosidic bonds between adjacent glucose molecules
  • Position of bonds cause chain to coil in a spiral shape

Amylopectin

  • Polymer of glucose with side branches
  • 1, 6 glycosidic bonds holding side branches onto main chain

A-level Biology (Edexcel Salters) (7 decks)

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