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IGCSE Biology > B7.2 : Circulatory Systems and Blood > Flashcards

B7.2 : Circulatory Systems and Blood Flashcards

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1
Q

Circulatory Systems

A

All animals have circulatory systems to transport things around their bodies. These systems are made of blood vessels, a pump (the heart) and valves to stop blood moving in the wrong direction.

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2
Q

Single Circulatory System

A

Fish have what is known as a single circulatory system because blood only travels through the heart once in every circuit around the body.

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3
Q

Double Circulatory System

A
  1. Mammals have a double circulatory system, where blood travels through the heart twice per circuit.
  2. Double circulatory systems get oxygenated blood to tissues (like muscles) that need it faster than single circulatory systems.
  3. The concentration gradient between the blood and cells is also better maintained in double circulatory systems, so substances are exchanged between the blood and body cells faster.
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4
Q

Double Circulatory System Process

A
  1. The circulatory system of mammals has three key components: blood vessels, blood and the heart. It is called a double circulatory system because blood passes through the heart twice per circuit:
  2. The first is when blood enters the heart: Deoxygenated blood from the body enters the into the right atrium of the heart.
  3. Then Blood pumped to lungs: This deoxygenated blood is pumped out of the heart and towards the lungs by the right ventricle.
  4. Lungs oxygenate the blood: At the lungs, the deoxygenated blood exchanges carbon dioxide for oxygen. This is how it becomes oxygenated (contains oxygen).
  5. Blood returns to the heart: Oxygenated blood returns to the left atrium of the heart.
  6. Blood pumped into the body: This oxygenated blood is pumped out of the heart and to the body by the left ventricle.
  7. Blood returns to the heart: The oxygenated blood gives its oxygen to body cells in exchange for carbon dioxide. The blood becomes deoxygenated and returns to the heart.
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5
Q

Right and Left pump of the heart

A
  1. The right pump sends deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart.
  2. The left pump sends the newly oxygenated blood around the body. By the time this blood returns to the heart, it has returned to a deoxygenated state.
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6
Q

Single vs double circulatory systems

A

Double circulatory systems of mammals oxygenate the body’s tissues faster and exchange substances between the blood and tissues faster than the single circulatory systems of fish.

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7
Q

Heart pumping

A
  1. A group of cells in the right atrium act as a pacemaker, controlling the pumping heart.
  2. When a heart beats blood enters the heart via the atria.
  3. Once filled with blood, the atria contract, forcing blood down into the ventricles below.
  4. When the ventricles contract, they force blood to exit the heart.
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8
Q

Structure of the heart

A
  1. The heart is the muscular organ that pumps blood around the body.
  2. The heart has four chambers: the left and right atria and the left and right ventricles.
  3. The wall that separates the right and left ventricles is called the septum and is important for keeping oxygenated and deoxygenated blood separate.
  4. The atrioventricular valves stop back-flow of blood from the ventricles into the atria.
  5. The semilunar valves stop back-flow of blood back into the heart.
  6. The left ventricle wall is much thicker than the right because it has to force blood out of the heart at a higher pressure, because the blood has to travel further (around the whole body). The right ventricle only has to pump blood to the lungs.
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9
Q

Why might someone be fitted with an artificial pacemaker?

A
  1. A group of cells in the right atrium act as a pacemaker to control the heart’s beating.
  2. Irregular heart rates can be corrected using electrical devices, known as artificial pacemakers.
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10
Q

Artery structure

A
  1. thicker outer wall
  2. thick layer of muscle and elastic fibres
  3. Narrow central tube (lumen)
  4. Smooth lining so no obstruction to the flow of blood
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11
Q

Blood vessels

A
  1. Blood flows around the body in a system of tube-like blood vessels arranged in such a way that they all eventually lead back to the heart
  2. The blood flows away from the heart in vessels called arteries and it flows back towards the heart in vessels called veins
  3. Joining the arteries and veins are the capillaries
  4. Types: veins, arteries, and capillaries
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12
Q

Adaptations and functions of the artery

A
  1. Carries blood away from the heart to the tissues
  2. Blood is at high pressure
  3. Blood is rich in oxygen, low in carbon dioxide (except in the pulmonary artery)
  4. Elastic walls expand and relax as blood is forced out of the heart . This causes the pulse that you can feel is you press an artery such as in the wrist
  5. Thick walls withstand the high pressure of blood to prevent the blood vessel from rupturing of bursting. Rings of muscle can narrow or widen the the artery and control the blood flow in it according to the body’s needs
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13
Q

Structure of the vein

A
  1. thin outer wall
  2. Thin layer of muscle and elastic fibres
  3. Wide central tube (lumen)
  4. Flap of watch pocket valve
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14
Q

Adaptations and functions of the vein

A
  1. Carries blood from the tissues to the heart
  2. Blood is at low pressure
  3. Blood is low in oxygen, high in carbon dioxide (except in the pulmonary vein
  4. Valves prevent the backflow of blood. Blood is at low pressure, but nearby muscles squeeze the veins and help push blood back towards the heart
  5. Large diameter and thin walls reduce resistance to the flow of blood
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15
Q

Flow of blood

A
  1. Right ventricle
  2. Pulmonary artery
  3. Lungs
  4. Pulmonary vein
  5. Left atrium
  6. Left ventricle
  7. Aorta
  8. Arteries
  9. Capillaries
  10. Body cells
  11. Capillaries
  12. Veins
  13. Vena Cava
  14. Right atrium
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16
Q

Pulmonary artery

A

unlike other arteries, this vessel carries deoxygenated blood which also has a high carbon dioxide concentration

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17
Q

vena cava

A
  1. the main vein of the body

2. returns deoxygenated blood at low pressure from organs and tissues to the heart

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18
Q

Pulmonary vein

A
  1. unlike other veins, this vessel carries oxygenated blood

2. It has the highest oxygen and lowest carbon dioxide concentration in the circulation

19
Q

Aorta

A
  1. the main artery of the body

2. supplies oxygenated blood, at high pressure, to the organs and tissues of the body

20
Q

Capillaries

A
  1. to reach the cells that need them, dissolves substances carries in the blood have to move from the blood vessels to the tissues and waste materials need to go from the tissues to the blood to be carried away
  2. Dissolves substances move between the blood and tissues by diffusion across the walls of very fine blood vessels called capillaries
21
Q

Capillaries function and adaptations

A
  1. the walls of the capillaries are only one cell thick so that substances do not have very far to diffuse through them
  2. the capillaries are highly branched so they cover an enormous surface area, giving more space for diffusion to occur
  3. The capillary beds are constantly supplied with fresh blood, keeping up the concentration gradients of dissolved substances between blood and tissues. Without these concentrations gradients diffusion could not occur
22
Q

Transportation in the body

A
  1. All living organisms require energy, which is released from food and oxygen in the process of respiration
  2. All living cells in the body need energy, and so glucose and oxygen must be transported throughout the body
  3. In some small animals, substances are transported in and out of the body, and from one tissue to another, by the process of diffusion
  4. Larger complex organisms, such as humans have a small surface area in relation to their relatively large volume
  5. As a result, cells near the centre of the body are some distance away from contact with the atmosphere, and may also be some distance from the gut where food is digested
  6. Cells inside such large organisms cannot gain enough oxygen and glucose by diffusion alone so they use a transport system.
23
Q

Transport system

A
  1. To supply oxygen and glucose as well as other substances, large organisms have a specialised transport system
  2. This system called the blood vascular system in all vertebrate animals, is an example of a mass flow system
  3. A mass flow system carries large volumes of fluid to all parts of the organism
24
Q

Parts of a mass flow system

A
  1. medium
  2. system of tubes
  3. a pump
  4. sites of exchange
25
Q

medium

A
  1. the fluid that flows in the system and carries materials around the body.
  2. This is the blood
26
Q

System of tubes

A
  1. carries the fluid from place to place

2. arteries and veins

27
Q

pump

A
  1. supplies pressure to keep the fluid moving through the tubes
  2. heart
28
Q

sites of exchange

A
  1. allow materials delivered by the blood to enter the tissues that need them
  2. capillaries
29
Q

Blood

A
  1. Humans blood consists of blood cells which are suspended in a watery liquid known as plasma
30
Q

Types of blood cells

A
  1. Red blood cells
  2. White bloods cells (phagocytes and lymphocytes(
  3. Platelets
31
Q

Red blood cells function

A
  1. transport oxygen from lungs to all respiring tissues

2. prepare carbon dioxide for transport from all respiring tissues to lungs

32
Q

red blood cell adaptations

A
  1. contain haemoglobin, which is an iron-containing pigment which picks up oxygen at the lungs and lets go of it at the tissues
  2. Once matured, it has no nucleus leaving more space for haemoglobin
  3. Cells are small and flexible, so can squeeze through narrow capillaries
  4. Biconcave disc shape (larger surface area compared to their volume)
33
Q

Type of White blood cells

A
  1. phagocytes

2. lymphocytes

34
Q

Phagocytes (WBC) function

A
  1. remove any microorganisms that invade the body and might cause infection
  2. engulfs and ingest any foreign particles
35
Q

Phagocytes (WBC) adaptation

A
  1. irregular shaped nucleus allows cells to squeeze through gaps in walls of capillaries
  2. Enzymes in cytoplasm digest microorganisms once engulfed
  3. Sensitive cell surface membrane can detect microorganisms
36
Q

Lymphocytes (WBC) function

A
  1. produce antibodies - proteins that help in the defence against disease
  2. Each antibody works on a specific pathogen, once infected the lymphocytes remember the required antibody for a specific pathogen if it entered the body again. This makes you immune to a disease
37
Q

Lymphocytes (WBC) adaptation

A

large nucleus contains many copies of genes for the control of antibody protein production

38
Q

Platelets function

A

cell fragments involved in blood clotting

39
Q

platelets adaptation

A

can release blood-clotting enzymes

40
Q

Haemoglobin and oxygen

A
  1. Haemoglobin combines easily with oxygen as the blood passes through the lungs it forms oxyhaemoglobin.
  2. Haemoglobin + Oxygen —> Oxyhaemoglobin
41
Q

How anti-bodies attack pathogens

A
  1. Making them stick together (agglutinate)
  2. Dissolve their membranes
  3. Neutralise toxins
  4. Marks pathogens for phagocytes.
  5. Immobilises pathogens
42
Q

Process of clotting blood

A
  1. When skin / blood vessels damaged.
  2. Collagen fibres are exposed.
  3. Platelets stick together and form a platelet plug with other blood cells.
  4. Stimulates platelets to release clotting factors.
  5. Converts soluble fibrinogen into insoluble fibrin.
  6. To create a fibrin mesh.
  7. Seals / plugs the damaged vessel preventing further blood loss and preventing pathogen entry.
43
Q

Plasma

A
  1. watery liquid
  2. Carries dissolved food molecules such as glucose and amino acids, waste materials such as urea, and some control molecules such as hormones
  3. Because the plasma is largely water, it has a very high specific heat capacity which means it is able to distribute heat around the body

IGCSE Biology (31 decks)

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