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IGCSE Biology > II: 7.2 - Transport in humans > Flashcards

II: 7.2 - Transport in humans Flashcards

7.2 Transport in humans 7.2.1 Heart 7.2.2 Arteries, veins and capillaries 7.2.3 Blood

1
Q

What is the circulatory system?

A

A system of tubes (veins, capillaries, arteries) with a pump (heart) and valves (in heart and veins) to ensure one-way flow of blood.

We need a transport system to deliver oxygen, nutrients and other substances to all our body cells, and take away waste products from them.

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2
Q

Describe the double circulation of blood

A

Systemic:

  • High pressure circulation transporting oxygenated blood to the body tissues and deoxygenated blood from them
  • Longer distance, so stronger circulation and higher pressure needed

Pulmonary:

  • Low pressure circulation transporting deoxygenated blood to the lungs and oxygenated blood from the lungs
  • Shorter distance, so weaker circulation and lower pressure needed
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3
Q

State the name and function of A

A

Superior vena cava

Carries in deoxygenated blood from the upper body

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4
Q

State the name and function of B

A

Pulmonary vein

Carries oxygenated blood from the lungs to the left atrium

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5
Q

State the name and function of C

A

Right atrium

Receives deoxygenated blood from the body via the vena cava

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6
Q

State the name and function of D

A

Pulmonary semi-lunar valve

Prevents a backflow of blood between the right ventricle and pulmonary artery

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7
Q

State the name and function of E

A

Tricuspid valve

Prevents a backflow of blood between the right atrium and right ventricle

Remember: tricuspid valve on the right side

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8
Q

State the name and function of F

A

Inferior vena cava

Carries in deoxygenated blood from the lower body

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9
Q

State the name and function of G

A

Aorta

Carries out oxygenated blood from the left ventricle to the rest of the body

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10
Q

State the name and function of H

A

Pulmonary artery

Carries deoxygenated blood from the right ventricle to the lungs

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11
Q

State the name and function of I

A

Left atrium

Receives oxygenated blood from the lungs via the pulmonary vein

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12
Q

State the name and function of J

A

Bicuspid valve

Prevents a backflow of blood between the left atrium and left ventricle

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13
Q

State the name and function of K

A

Aortic semi-lunar valve

Prevents a backflow of blood from the aorta to the left ventricle

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14
Q

State the name and function of L

A

Left ventricle

Pumps oxygenated blood to the body tissues via the aorta

Has a thick muscular wall as high pressure is needed to reach the whole body

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15
Q

State the name and function of M

A

Septum

Separates the two sides of the heart

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16
Q

Describe the steps of the cardiac cycle

A
  1. Atrial systole: artia contract and push blood into the ventricles
  2. Ventricular systole: ventricles contract and puch blood into the arteries; bicuspid and tricuspid valves close
  3. General/cardiac diastole: all chambers relax, allowing blood to seep in; semi-lunar valves close
17
Q

State and explain the effect of physical activity on pulse rate

A

Increased physical activity usually leads to an increased pulse rate.

This is because physical activity makes the heart beat more quickly and more deeply, for an increased circulation of blood so that more oxygen and glucose can get to the muscles.

Fitter people’s pulse rate returns to normal faster after physical activity as their hearts can pump blood more effectively.

18
Q

Describe coronary heart disease and list the symptoms

A
  • The coronary arteries bring blood and oxygen to the heart. Fatty material and other substances form a plaque build-up on the walls of the coronary arteries. This may also be called hardening of the arteries.
  • This build-up causes the arteries to get narrow.
  • As a result, blood flow to the heart can slow down or stop
  • The heart muscle cells are deprived of oxygen and glucose, and poisonous wastes such as lactic acid build up
  • Part of the heart muscle stops contracting, causing a heart attack
  • Symptoms:
    • Chest pain or discomfort (also known as angina)
    • Shortness of breath and fatigue with activity (exertion)
19
Q

State the possible causes and preventive measures of coronary heart disease

A

Causes:

  • diet
  • stress
  • smoking
  • alcohol

Preventative measures:

  • have a healthy, balanced diet
  • exercise at least 30 minutes a day
  • don’t smoke
  • avoid excessive consumption of alcohol
  • learn healthy ways to cope with stress through special classes or programs, or things like meditation or yoga
20
Q

Name the main blood vessels to and from the heart, lungs, liver and kidney

A 
Lungs→heart = Pulmonary vein
Liver→heart = Hepatic vein
Kidneys→heart = Renal vein
Heart→lungs = Pulmonary artery
Heart→liver = Hepatic artery
Heart→kidneys = Renal artery
21
Q

Describe the function and structure of arteries

A
  • carry (oxygenated) blood away from the heart
  • small lumen to maintain high pressure
  • thick muscle layer to withstand high pressure
  • elastic fibres help to pulse blood
  • high pressure prevents backflow of blood
22
Q

Describe the function and structure of veins

A
  • carry (deoxygenated) blood to the heart
  • large lumen reduces resistance to blood flow
  • thinner layer of muscle and elastic fibres as they do not need to withstand high pressure
  • have valves to prevent a backflow of blood
  • in the legs, the muscles squeeze blood up against gravity
23
Q

Describe the function and structure of capillaries

A
  • takes oxygenated blood from arteries to cells, and deoxygenated blood from cells to veins
  • walls are only one cell thick
  • often as little as 0.001mm in diameter
  • thin walls allow liquid to pass through, i.e. they are permeable
24
Q

Describe the transfer of materials between capillaries and tissue fluid

A
  • tissue fluid diffuses out of the capillaries, containing nutrients and oxygen
  • the slow flow rate in the capillaries allows plenty of time for the exchange of O2, CO2, nutrients and waste
  • some tissue fluid, now containing waste products, is absorbed back into the capillaries, some enters lymphatic vessels
  • fluid in lymphatic vessels (lymph) eventually empties back into the blood
25
Q

List the four components of blood

A
  1. Red blood cells
  2. White blood cells
  3. Plasma
  4. Platelets
26
Q

Identify this component of blood and state its functions and adaptations

A

Red blood cell

  • oxygen transport
  • life span - about 120 days
  • no nucleus, so more capacity for oxygen
  • contain haemoglobin - a red pigment/protein combined with iron
  • bi-concave shape to increase surface area
  • flexible so that they can squeeze through narrow blood vessels
  • thin cell membranes to let oxygen diffuse through quickly

Oxygen is carried as oxyhaemoglobin, an unstable product formed from oxygen and haemoglobin that breaks down in places of low oxygen concentration.

27
Q

Identify the following component of blood and state its function and adaptations

A

Lymphocyte

  • defense against disease - antibody formation
  • very large nucleus holds instructions to produce many different antibodies
28
Q

Describe how antibodies in the immune system help to defend against disease

A
  • antibodies - proteins which attack pathogens by:
    • attaching to the surface of the pathogen and make it easier for phagocytes to ingest it
    • clumping the bacteria together
    • neutralising the toxins produced by the pathogen
    • locking onto it and destroying it
  • antibodies are specific, i.e. each type will only attack a certain pathogen
  • lymphocytes produce antibodies when a pathogen has been detected by its antigens - chemicals on the surface of the cells

Tissue rejection happens as a result of white blood cells not recognising the antigens on the tissue as belonging to oneself, and attempt to destroy it.

29
Q

Identify the following component of blood, and state its functions and adaptations

A

Phagocyte

  • defense against disease - engulfs and destroys pathogens (phagocytosis)
  • life span - about 20 days
  • lobed nucleus allow it to change shape and squeeze through small spaces
  • has vesicles containing digestive enzymes to digest/destroy pathogens
30
Q

Describe phagocytosis

A
  1. Pathogen is detected/identified
  2. False feet formed to surround pathogen
  3. Pathogen engulfed with water droplet
  4. Digestive enzymes digest pathogen
  5. Toxins released from pathogen, killing the phagocyte
31
Q

Identify the following component of blood and state its function

A

Platelets

  • fragments of red blood cells
  • causes clotting (helps heal wounds)
  • produces clotting factor
32
Q

Describe the process of clotting

A
  • person gets wounded
  • platelets produce clotting factor
  • clotting factor converts fibrinogen (soluble) to fibrin (insoluble)
  • platelets, red blood cells and white blood cells get trapped in fibrin network/mesh, forming a clot
  • this eventually dries to form a scab

Calcium is needed for this process

33
Q

State the function of blood plasma

A

Transport of blood cells, ions, soluble nutrients, hormones, carbon dioxide, urea and plasma proteins

(also a little dissolved oxygen, only about 1% of oxygen is carried in plasma)

34
Q

Describe the function of the lymphatic system

A
  • Circulation of body fluids, and the production of lymphocytes
  • Lymph node contains many lymphocytes which filter lymph
  • Tissue fluid: made when plasma is squeezed out of capillaries
  • Substances diffuse between cells and tissue fluid
  • Some tissue fluid returns to the capillaries by osmosis
  • Lymph vessels collect excess tissue fluid (now called lymph), have valves to prevent backflow
  • Lymph vessels from all parts ot the body join up to make two thoracic ducts
  • Ducts join with subclavian veins, blood flows to heart

IGCSE Biology (24 decks)

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