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Edexcel A Biology > 1.1 Circulatory System > Flashcards

1.1 Circulatory System Flashcards

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1
Q

Explain what is meant by the dipole nature of water

A
  • Oxygen has δ- charge bonded to two hydrogens with δ+ charges (bent shape)
  • uneven distribution of charge - polar molecule
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2
Q

Explain how the properties of water are essential for organisms

A
  • good solvent - important for chemical reactions in solutions
  • cohesive and adhesive - important for mass transport
  • high specific heat capacity - helps keep stable temperatures
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3
Q

Explain how water is cohesive/adhesive and has a high specific heat capacity

A

hydrogen bonding - electrostatic forces between δ- oxygens and δ+ hydrogens - causes water to be “sticky” and takes a lot of energy to break (high heat capacity)

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4
Q

Explain why water is a good solvent

A

Dipole nature allows breakdown of polar molecules (often ionic) and into solution

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5
Q

State types of circulatory systems, giving examples of organisms with each one

A
  • No circulatory system (unicellular organisms)
  • Open circulatory system (invertebrates)
  • Closed single circulatory system (fish)
  • Closed double circulatory system (mammals)
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6
Q

Explain reasons for differing types of circulatory systems

A

As metabolic rate and SA:V decreases, the organism cannot rely on diffusion alone to get the needed oxygen for respiration (+ other nutrients)

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7
Q

Define the term mass flow

A

The movement of fluid (and solute) from an area of high to low concentration in a closed vessel

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8
Q

Explain why mass transport systems useful

A
  1. Move substances around the body quickly
  2. Maintain diffusion gradients at sites of gas exchange
  3. Supply reactants to cells and remove waste products
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9
Q

Explain the flow of blood through the heart + around the body, starting at the lungs

A
  1. Lungs, enter the heart through pulmonary vein
  2. left atrium to left ventricle via mitral/bicuspid/atrioventricular valve
  3. to aorta through semilunar/aortic valve
  4. travels around the body, artery into arterioles into capillaries
  5. gas exchange occurs, now deoxygenated blood
  6. capillaries into venioles into veins into the vena cava
  7. right atrium to right ventricle through tricuspid/atrioventricular valve
  8. to pulmonary artery through semilunar/pulmonary valve
  9. back to lungs
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10
Q

Explain the function of coronary arteries, and what can happen if they malfunction

A

Provides blood flow to the heart muscles, if the blood flow is blocked, the muscles can fail and cells die, causing a myocardial infarction (heart attack) where the heart fails to pump properly

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11
Q

Explain the properties of arteries

A
  • thick walled with narrow lumen to maintain high blood pressure
  • muscular to contract and narrow lumen (vasoconstriction)
  • smooth highly folded endothelium and elastic tissue, to expand with higher blood pressure and prevent damage
  • high collagen in outer walls to protect against damage from high pressure
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12
Q

Explain the properties of veins

A
  • wider lumen to carry more blood at lower pressure
  • less elastic/muscle tissue due to lower pressure
  • valves to prevent backflow of blood
  • smooth endothelium, to reduce friction, and damage
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13
Q

Explain the properties of capillaries

A
  • capillary walls one cell thick to reduce diffusion distance
  • porous to allow diffusion
  • narrow lumen
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14
Q

State the equation to calculate magnification

A

m = i / a
m - x magnification
i - image size
a - actual size

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15
Q

State components of blood

A
  • plasma (made of water, proteins, ions, nutrients, hormones etc)
  • cells
    • erythrocytes (red blood cells)
    • leukocytes (white blood cells)
    • thrombocytes (platelets)
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16
Q

State the functions of blood

A
  • transport
  • immunity/defence
  • thermoregulation
  • maintaining pH of body fluids
17
Q

Name and describe the stages of the cardiac cycle

A

cardiac diastole

  • all chambers relaxed, blood flows freely
  • AV valves open, SL valves closed
    #atrial systole (ventricular diastole)
  • atria muscles contract, blood flows through atria into ventricles
  • AV valves open, SL valves closed
    #ventricular systole (atrial diastole)
  • ventricular muscles contract, blood flows through ventricles into arteries
  • AV valves closed, SL valves open
18
Q

PRACTICAL
Explain how you would investigate the effect of caffeine on heart rate

A

IV: caffeine conc (0M, 0.1M … 0.4M)
DV: heart rate of Daphnia (bpm)
CVs: temp (use thermometer), time to acclimatize (use stopwatch), size of daphnia etc.
Method: put daphnia on cavity slide, in soaked cotton wool, dab with tissue and add caffeine solution, allow to acclimatize, use microscope to measure heart rate, repeat
Analysis: work out mean values, and standard deviation on bar chart
Expected conclusion: higher caffeine conc = faster heart rate (caffeine is a stimulant)

19
Q

PRACTICAL
State the reasons and ethical considerations of using Daphnia in investigations

A
  • daphnia are used because they are translucent, heart is visible
  • simple invertebrate, has a simple nervous system, so unlikely to feel pain
  • low caffeine conc, recovery tank, wide end pipettes used to reduce stress on Daphnia
20
Q

State the stages of the clotting cascade

A
  • damage to the vessel wall/endothelium releases thromboplastin
  • thromboplastin, Ca+ and K+ ions causes prothrombin to become thrombin
  • thrombin causes soluble fibrinogen to become insoluble fibrin
  • fibrin mesh, platelets and red blood cells form blood clot to patch up damage
21
Q

State the stages of the formation of an atheroma

A
  1. damage occurs to endothelium (e.g. by high blood pressure) and cholesterol triggers inflammatory response
  2. white blood cells and lipids at damaged area clump together under endothelium (forms “fatty streak”)
  3. more damage and dead cells build up the fibrous plaque, with the addition of calcium making it harder
  4. this forms an atheroma, which narrows the lumen and causes higher blood pressure
  5. many atheromas forming and hardening is called atherosclerosis
22
Q

State the differences between a myocardial infarction, a stroke and an aneurysm

A
  • myocardial infarction: lack of oxygen to heart tissue, causes tissue damage/death
  • stroke: lack of oxygen to brain tissue, causes tissue damage/death
  • aneurysm: swelling of an artery, can burst and blood loss may be fatal
23
Q

Explain how atherosclerosis increases risk of heart attacks, DVT and strokes

A

Atheroma’s harden artery walls, and narrow lumens, so there is higher blood pressure.
Atheroma’s then rupture and cause thrombosis (blood clotting), blocking blood flow (can happen in arteries to brain/heart or deep veins)

Edexcel A Biology (6 decks)

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