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Edexcel IGCSE Biology > Transport (Humans) > Flashcards

Transport (Humans) Flashcards

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1
Q

What are the four things blood consists of?

A

Red blood cells, white blood cells, platelets and plasma

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2
Q

What percentage of the total volume of blood does each of the four things make up?

A
  • Red blood cells: 45%
  • Plasma: 55%
  • Platelets and white blood cells: <1%
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3
Q

What is plasma?

A
  • A straw coloured liquid in which other components of blood are suspended in
  • It is also what all other substances transported by the blood and suspended in, and it is necessary to transport these substances around the body
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4
Q

Which substances are transported in blood plasma?

A
  • Carbon dioxide
  • Digested nutrients (including mineral ions)
  • Urea
  • Hormones
  • Heat energy

  • Oxygen is carried in the red blood cells, not plasma
  • Plasma is comprised of 90% water, so it also carries water
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5
Q

What are the adaptations of red blood cells that make them suitable for the transportation of oxygen?

A
  • They are full of haemoglobin, a protein which binds to oxygen
  • They have no nucleus to allow for more space for haemoglobin
  • They are small and have a bioconvave disk shape which allows them to have a small surface area to volume ratio for optimal diffusion
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6
Q

What is the pathway of blood through the heart?

A
  • Vena Cava
  • Right atrium
  • Tricuspid valve
  • Right ventricle
  • Semilunar valve
  • Pulmonary artery
  • Lungs (oxygenated)
  • Pulmonary vein
  • Left atrium
  • Bicuspid valve
  • Left ventricle
  • Semilunar Valve
  • Aorta
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7
Q

Why are there thicker muscular walls on the left ventricle of the heart?

A

It must pump blood a much further distance (around the whole body) at a high pressure, compared to the right ventricle which only needs to pump it to the lungs

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8
Q

What are valves for in the heart?

A

Preventing backflow

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9
Q

What is the septum for in the heart?

A

Dividing the right and left ventricle and stopping the oxygenated and deoxygenated blood from mixing, which could cause blood being pumped to the rest of the body to be less oxygenated

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10
Q

What happens to heartrate during exercise and why?

A
  • It increases
  • More muscular contractions lead to increased need for respiration
  • More glucose and oxygen must be supplied, and more carbon dioxide (and potentially lactic acid) must be removed due to increased respiration
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11
Q

What happens to heartrate under the influence of adrenaline and why?

A

It increases as more blood with oxygen and glucose is pumped to the muscles in preparation for running/fighting

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12
Q

What are the factors that increase the risk of developing coronary heart disease?

A
  • Obesity - Extra weight puts strain on heart, and if the person has diabetes, this can damage blood vessels
  • High blood pressure - Increases force of blood against vessels, damaging them
  • High saturated fat/cholesterol diet - Is what causes the build up of fatty plaques
  • Smoking - Can contribute to plaque build up and increase blood pressure, carbon monoxide can also reduce oxygen carrying capacity, nicotine increases blood pressure
  • Lack of exercise - Exercise makes heart and circulation better and more efficient and reduces cholesterol and blood pressure
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13
Q

What are the distinct features of arteries?

A
  • Carry blood away from the heart
  • Have a thick muscular and elastic wall to carry blood at high pressure
  • Have a small lumen to maintain a high pressure
  • Carry oxygenated blood, apart from the pulmonary artery
  • Have connective tissue which provides strength

  • The blood is under high pressure in the arteries because it has just been pumped out of the left ventricle at extreme force
  • Arterioles are the smaller arties which branch off of arteries
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14
Q

What are the distinct features of veins?

A
  • Carry blood towards the heart
  • Have less muscular, elastic and connective tissue as blood is being carried at lower pressures (as it has not just been pumped out the left ventricle)
  • Have a large lumen to allow blood to flow at low pressures
  • Carry deoxygenated blood, apart from the pulmonary vein
  • Have valves to stop the backflow of blood

They need valves because the blood is at a low enough pressure for backflow to occur

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15
Q

What are the distinct features of capillaries?

A
  • Very small to allow them and the blood they are carrying to get up close to organs
  • Capillary walls are one cell thick and permeable to allow for easy diffusion
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16
Q

How does the double circulatory system work?

A
  • Blood is sent from the heart to the lungs to be oxygenated - This is the pulmonary system
  • This oxygenated blood is carried out of the heart by arteries to the organs and muscles, where the oxygenated blood enters capillaries and the oxygen diffuses across to the organs and muscles
  • The deoxygenated blood is then sent back to the heart through the veins - The last two bullet points comprise the systemic system
17
Q

What is the vein/artery that connects the heart to the lungs called?

A

Pulmonary vein/artery

18
Q

What is the vein called and what is the artery called that connects the body to the heart?

A
  • The vein is the vena cava
  • The artery is the aorta
19
Q

What is the vein/artery that connects the heart to the liver called?

A

Hepatic vein/artery

20
Q

What is the artery called that connects the heart to the gut (instestines)?

A

Mesenteric artery

21
Q

What is the vein called that connects the gut (intestines) to the liver?

A

Hepatic portal vein

This is the vein that carries all the digested food to the liver

22
Q

What is the vein/artery that connects the heart to the kidneys called?

A

Renal vein/artery

23
Q

What are the two types of white blood cells that the body uses to deal with an infection?

A
  • Phagocytes
  • Lymphocytes
24
Q

How do phagocytes work?

A
  • They carry out phagocytosis by engulfing and digesting foreign invaders
  • Once they detect a pathogenic cell, they will engulf it and release digestive enzymes in order to digest it, absorbing useful substances like amino acids
  • Assimilation occurs, and the digestive products are expelled from the phagocyte
  • This response is non-specific
25
Q

How do lymphocytes (T cells) work?

A
  • Each lymphocyte will produce antibodies specific to a single virus’s antigens (proteins on the surface of a cell)
  • When a lymphocyte encounters a pathogen with antigens specific to the antibodies it produces, it divides in order to mass produce this antibody
  • The antibodies cause agglutination of pathogens, which clump them and restrict their movement for phagocytes to kill them
26
Q

What are memory cells (B cells) and how are they useful?

A
  • Memory cells are lymphocytes which produce antibodies specific to a pathogen the individual has previously been infected with which stay in the body in large numbers
  • This is so that if the individual gets infected with the same pathogens, the antibody response will be much faster and greater and will be able to deal with the infection before symptoms are exhibited
27
Q

How do vaccines work?

A
  • A dead version of the virus is injected into the bloodstream
  • Lymphocytes will recognise the antigens on the dead pathogen, and the lymphocyte specific to it will divide, producing many antibodies and leaving memory cells
  • If a live version of the virus enters the body, the memory cells will provide a faster and greater immune response and the infection should be dealt with before symptoms are exhibited
28
Q

What are platelets?

A

Fragments of cells found in the blood plasma

29
Q

What are platelets for and how do they work?

A
  • They are involved in blood clotting and forming scabs where the skin has been cut/punctured
  • They collect at the site of the wound and clump together, as well as release chemicals which cause soluble fibrinogen proteins to convert into insoluble fibrin which forms an insoluble mesh across the wound, trapping red blood cells and forming a clot
  • The clot dries into a scab, which remains until new skin has grown underneath it
30
Q

What are the purposes of clotting?

A
  • It prevents continued blood loss from wounds
  • Scab formation prevents the entry of pathogens into the bloodstream which could cause infection

Edexcel IGCSE Biology (25 decks)

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