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IGCSE Biology > Topic 5 Transport in Humans > Flashcards

Topic 5 Transport in Humans Flashcards

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1
Q

What is mass transport?

A

• movement of relatively large quantities of molecules at high speeds via transport system eg circulatory system

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2
Q

What are the percentages of components of blood?

A

Plasma = 55%

White blood cells/platelets = less than 1%

Red blood cells = 45%

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3
Q

What is the structure of plasma?

A
  • mostly water

- some proteins + hormones

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4
Q

What is the function of the plasma?

A

Transports:

  • carbon dioxide
  • digested food molecules
  • urea
  • hormones
  • heat energy
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5
Q

Describe the structure and function of red blood cells

A
  1. Carry oxygen round body in form oxyhaemoglobin
  2. Oxygen binds to haemoglobin protein inside red blood cell
  3. Biconcave shape (increase sa)
  4. No nucleus (more room for haemoglobin)
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6
Q

Practical: investigate the evolution of carbon dioxide from maggots

A
  1. Suspend maggots inside test tube on mesh

2. Hydrogen carbonate indicator underneath, will go orange as maggots are respiring aerobically -> co2 produced

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7
Q

Practical: investigate the evolution of heat from respiring seeds

A
  1. Use two vacuum flasks: one containing living germinating seeds + other containing boiled seeds
  2. Insert thermometer with cotton wool bung to prevent it falling out, to measure temp
  3. Measure initial temperature
  4. Leave seeds for a few days + measure end temperature
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8
Q

What would the result be of the germinating seed practical?

A
  • Germinating seeds would release heat energy since they are respiring so temp would increase
  • boiled seeds enzymes have denatured, + enzymes required for respiration, so no heat energy released so temp stays same
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9
Q

Describe the method for the yeast practical

A
  1. Measure fixed vol of glucose solution + add to boiling tube
  2. Place in water bath for 5 mins to acclimatise
  3. Weigh fixed mass of yeast + add to boiling tube
  4. Use pipette to oil to cover top of solution to prevent oxygen from entering (prevent aerobic respiration)
  5. Use delivery tube + bung to connect boiling tube to another test tube half filled w lime water
  6. Start stop clock and count no of bubbles produced in one min
  7. Repeat + take a mean at each water bath temp
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10
Q

What are the control variables in the yeast experiment?

A
  • mass of yeast
  • volume and concentration of sugar solution
  • time for timing
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11
Q

What are sources of error in yeast experiment?

A
  • bubbles may form too quickly to be counted accurately

- diff vol of co2 released depending on size of bubble

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12
Q

What are the results of yeast experiment?

A

0 degrees enzymes still work but very slowly, so rate of respiration = low

40 degrees optimum temp

80 degrees denatured = so rate of respiration very low

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13
Q

Describe structure and function of two main white blood cell types

A
  1. Phagocyte
    - > multi lobed nucleus
    - > engulfs bacteria and digests them w/ enzymes
  2. Lymphocytes
    - > large nucleus + halo of cytoplasm
    - > release antibodies that bind to antigens on surface of pathogens and mark them for engulfing by phagocyte
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14
Q

Describe the process of a primary immune response in an animal

A

Primary immune response
1. Pathogens present

  1. Lymphocytes produce antibodies that are complementary to antigens on pathogen
  2. These attach to surface of pathogen, marking it out for phagocytes to engulf + destroy
  3. Some of the lymphocytes become memory cells + remain in the blood
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15
Q

How do vaccines work?

A
  1. Dead pathogen injected
  2. (Primary immune response) lymphocytes produce antibodies complementary to antigens on surface of pathogens
  3. Some of the lymphocytes will become memory cells + remain in the blood
  4. (Secondary immune response) If the pathogen is met, it is recognised by the memory cells which produce larger quantities of antibodies faster
  5. These attach to the surface of the pathogens, targeting it for destruction by phagocytes
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16
Q

What are platelets?

A
  • fragments of cells
  • produced in bone marrow
  • no nucleus
17
Q

How do platelets work?

A
  1. If skin = cut, exposure to air stimulates platelets to produce a chemical
  2. This causes soluble plasma protein fibrinogen to change into insoluble fibres of fibrin, forming a net across wound.
  3. Blood cells get trapped in this net forming a clot
  4. Prevents further loss of blood and entry of pathogens
  5. Clot develops into scab which protects damaged tissue while new skin grows
18
Q

What is the structure of the heart?

A
  1. Muscular walls to provide strong heartbeat
  2. Muscular wall of left ventricle = thicker -> blood needs to be pumped all around body rather than just to lung like right right ventricle
  3. 4 chambers to separate oxygenated from deoxygenated blood
  4. Valves to prevent blood back flow
  5. Coronary arteries that supply heart with oxygenated blood
19
Q

Describe the cardiac cycle

A
  1. Atria contract-> atrial pressure > ventricle pressure - atrioventricular valves open + blood moves into ventricles
  2. ventricles contract -> ventricular pressure > arterial pressure - semi lunar valves open + blood enters arteries (av valves shut)
  3. Ventricles relax - semi lunar valves shut as arterial pressure > ventricle pressure
20
Q

Explain how the heart rate changes during exercise and under the influence of adrenaline

A
  1. Muscles require more energy - respiring at higher rate -> heart rate will increase -> pump more oxygen and nutrients round body and remove waster products
  2. Stroke volume will also increase - heart will pump more each time
  3. Adrenaline = hormone released from adrenal glands
    - > makes heart beat faster + harder
21
Q

What are causes of CHD?

A
  • high blood pressure
  • poor diet
  • smoking
  • stress
  • lack of exercise
22
Q

Why is a diet rich in fat bad and what does this go on to cause?

A
  • increases cholesterol levels
    1. Cholesterol + other fatty substances deposited in coronary arteries (atherosclerosis)
    2. Causes blockage, preventing RBCs from passing through
    3. RBCs stick together and form clot
    4. Prevents oxygen + glucose from reaching cardiac muscle cells
    5. Stops aerobic respiration + muscle cells start respiring anaerobically
    6. Build up of lactic acid + muscle can no longer contract
    7. Eventually muscle cells will die + person has a heart attack
23
Q

What is the structure + function of an artery?

A
  1. Carry OXYGENATED blood AWAY FROM HEART (except pulmonary artery, which is deoxygenated)
  2. Thick wall w muscle fibres + elastic tissue (able to stretch + recoil and withstand high pressure)
  3. Small lumen -> maintain high pressure
24
Q

What is the structure + function of a vein?

A
  1. carry DEOXYGENATED blood towards heart
  2. Large lumen -> blood low pressure
  3. Thin muscular walls w/ elastic tissue
  4. Valves to prevent back flow of blood
25
Q

What is the structure + function of a capillary?

A
  1. For gas exchange so carry both OXYGEN and CO2 to and from cells
  2. One cell thick for fast rate of diffusion (short diffusion pathway)
26
Q

Why do humans need a double circulation system?

A

Warm blooded, high metabolism, higher rate of aerobic respiration, need more efficient system to deliver oxygen at faster rate

27
Q

What is the first system?

A

Deoxygenated blood flows into right atrium then right ventricle, then into lungs via pulmonary artery and back via pulmonary vein

28
Q

What is the second system?

A

Oxygenated blood flows into left atrium then left ventricle, then to body via aorta and back via vena cava

29
Q

What is the aorta?

A

Main artery leaving heart to take oxygenated blood to body

30
Q

What is the vena cava?

A

Main vein, returning deoxygenated blood to heart from body

31
Q

What is pulmonary artery

A

Artery taking deoxygenated blood to lungs from heart

32
Q

What is pulmonary vein

A

Vein taking oxygenated blood from lungs to heart

33
Q

What is hepatic artery

A

Oxygenated blood to liver

34
Q

What is hepatic vein

A

Deoxygenated blood away from liver

35
Q

What is hepatic portal vein

A

Takes blood from gut to liver

36
Q

What is the renal artery

A

Branches off - takes oxygenated blood to kidneys

37
Q

What is the renal vein

A

Leaves kidneys with deoxygenated blood to go back to heart

38
Q

What is the effect of adrenaline on heart rate?

A

1) Secretion of adrenaline by adrenal glands
2) triggers increased breathing + heart rate
3) enables extra energy to be released for flight or flight response

IGCSE Biology (22 decks)

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