Chapter 7 - Transport in Man Flashcards
1
Q
Why is there not a need for a transport system in unicellular organisms?
A
- No part of the cell is far from external environment
- Exchange of materials occurs easily by diffusion
2
Q
Why is there a need for a transport system in multicellular organisms?
A
- Larger body, with reduced surface area to volume ratio
- Cells are located deeper in the body, further away from the external environment
- Diffusion is inadequate for transport
3
Q
Blood is a ________
A
fluid tissue
4
Q
Blood is made up of ________, ________, ________ and ________
A
plasma
red blood cells
white blood cells
platelets
5
Q
About ____% of blood is made up of plasma (the fluid part) and the other ____% is made up of blood cells and platelets
A
55
45
6
Q
Blood is separated into layers through ________
A
centrifugation
when spun in a high-speed centrifuge, it separates according to relative densities of the components
7
Q
What is plasma?
A
A pale yellowish liquid which is 90% water with a complex mixture of various dissolved substances
8
Q
What are the dissolved substances in plasma? [5]
A
- Proteins: fibrinogen, prothrombin and antibodies
- Mineral salts: hydrogencarbonates, chlorides, sodium, sulfates and phosphates of calcium
- Food substances: glucose, amino acids and fats
- Waste products: urea, uric acid and creatinine;
- Hormones: insulin
9
Q
Red blood cells (erythrocytes) constitute ____% of cells in the blood
A
99
10
Q
Red blood cells (erythrocytes) are produced in the ________
A
bone marrow
11
Q
Red blood cells (erythrocytes) are destroyed at the ________
A
spleen
12
Q
Red blood cells (erythrocytes) have a lifespan of ________
A
3-4 months
13
Q
What is the function of red blood cells?
A
To transport oxygen to cells in the body
14
Q
How is the red blood cell adapted for its function? [4]
A
- Filled with red pigment haemoglobin: essential for binding oxygen
- Absence of nucleus: allows more haemoglobin to be packed into the cell
- Biconcave shape: increases surface area to volume ratio for efficient uptake of oxygen
- Elastic: able to turn bell-shaped to squeeze through tiny blood capillaries
15
Q
White blood cells (leucocytes) are ________ in size than red blood cells but ________ in number
A
larger
fewer
16
Q
White blood cells (leucocytes) are produced in the ________
A
bone marrow
17
Q
White blood cells (leucocytes) are destroyed at the ________
A
spleen
18
Q
White blood cells (leucocytes) have a lifespan of ________
A
a few days
19
Q
Features of a white blood cell [3]
A
- Colourless as it does not contain haemoglobin
- Irregular in shape and contains a nucleus
- Mobile: is able to move, change its shape and squeeze through walls of the thinnest blood capillaries
20
Q
What are the types of white blood cells?
A
Lymphocytes and phagocytes
21
Q
Features of a lymphocyte [2]
A
- Large rounded nucleus
- Small amount of non-granular cytoplasm
22
Q
Function of a lymphocyte
A
Produces antibodies to protect the body from disease-causing microorganisms
23
Q
Features of a phagocyte [2]
A
- Lobed nucleus
- Granular cytoplasm
24
Q
Function of a phagocyte
A
Is able to ingest foreign particles such as bacteria
25
What are blood platelets (thrombocytes)?
- Not true cells
| - Fragments of cytoplasm which are membrane bound
26
Function of blood platelets (thrombocytes)
Important for the clotting of blood
27
Blood transfusion: what are antigens?
Proteins found on the surface of red blood cells
28
Blood transfusion: what are antibodies?
- Found in plasma
| - Able to recognise and bind the specific antigens on the red blood cells
29
Difference between antibodies and antibiotics
Antibodies: proteins that combat infections
Antibiotics: chemicals/medicine used to kill bacteria
30
Blood type A has antigen ____ on the red blood cell and antibody ____ in the plasma
A
| b
31
Blood type B has antigen ____ on the red blood cell and antibody ____ in the plasma
B
| a
32
Blood type O has antigen ____ on the red blood cell and antibody ____ in the plasma
(no antigens)
| a and b
33
Blood type AB has antigen ____ on the red blood cell and antibody ____ in the plasma
A and B
| no antibodies
34
What happens when Type A blood
| is added to Type B blood?
- Antibody a in plasma of recipient binds to antigen A on red blood cells of donor’s blood
- Agglutination (clumping) of red blood cells occurs
35
What is considered during a blood transfusion?
The effect of the recipient’s plasma on the donor’s red blood cells is considered
36
Which blood group is the universal donor and why?
Blood type O
- There are no antigens on the donor’s red blood cells, so the antibodies in recipient’s plasma will not react with the red blood cells
37
Which blood group is the universal acceptor and why?
Blood type AB
| - There are no antibodies in the plasma. Hence, no agglutination of red blood cells in donor’s blood will occur.
38
Blood acts as a ________
transport medium
39
What are the substances transported by blood?
- Digested food substances
- Excretory products (e.g. urea and carbon dioxide)
- Hormones
- Heat
- Oxygen
40
Transport of oxygen to body cells
→ Blood passes through lungs, oxygen diffuses from the air sacs in the lungs into the blood (simple diffusion)
→ Haemoglobin combines with oxygen to form oxyhaemoglobin
→ Blood transports oxygen to all the tissues of the body
→ At the tissue cells, oxyhaemoglobin releases the oxygen
41
Acclimatisation of blood at high altitudes
- People living at high altitudes have an increased number of red blood cells
- This increases the amount of haemoglobin in the blood
- More oxygen can be transported to the body cells per unit time
42
Protective function of blood
- Blood clotting
- Phagocytosis
- Production of antibodies
43
What is the clotting of blood and when does it occur?
- Blood clots when exposed to air
| - This seals the wound, prevents the entry of bacteria and further loss of blood
44
The clotting process
→ Damaged tissues and platelets release thrombokinase (an enzyme)
→ Thrombokinase converts prothrombin (inactive form) to thrombin (active form)
→ Thrombin converts soluble fibrinogen to insoluble fibrin threads which entangle blood cells and form a clot
45
What is phagocytosis?
The process of engulfing and ingesting foreign particles e.g. bacteria by phagocytes (a type of white blood cell)
46
What happens in phagocytosis?
- Phagocytes engulf (swallow) foreign particles such as bacteria
- The bacteria are ingested and digested in the phagocyte
47
Antibodies are produced by ________
lymphocytes
48
How do antibodies act?
- Antibodies bind to bacteria and cause their surface membranes to rupture
- Bacterial cells clump together in the presence of antibodies
- Toxins produced by bacteria are neutralised by antibodies
49
What is tissue or organ transplant?
The replacement of damaged or diseased tissue or organ with healthy tissue or organ from the same person or a donor
50
What is tissue rejection?
When the recipient of a tissue transplant produces antibodies to destroy the transplant
51
What are ways to reduce the risk of tissue rejection?
- Tissue match
| - Use of immunosuppressive drugs
52
The circulatory system is also known as the ________
cardiovascular system
53
What is the heart?
A muscular pump which pumps blood out of the heart and around the body
54
What are arteries?
Blood vessels that carry blood away from the heart
| aorta → arteries → arterioles
55
What are capillaries?
Microscopic blood vessels that arise from branches of the arterioles
56
What are veins?
A bundle of many venules which carry blood towards the heart
57
What are venules?
Small veins that are linked to the capillaries
58
What does the arterial blood contain?
- oxygen
| - glucose
59
What does venous blood contain?
- carbon dioxide
| - metabolic waste products
60
Function of arteries
Transport oxygenated blood from the heart to other organs in the body
61
How are arteries adapted for their function?
- Have thick, muscular walls to support blood coming from heart which is higher in pressure
- Muscles contract and relax to cause constriction and dilation of the artery respectively
62
Function of veins
Transport deoxygenated blood back to the heart
63
How are veins adapted for their function?
- Have relatively thin walls with less elastic tissue as flow of blood is slower and hence blood pressure is lower compared to arteries
- Have valves to prevent blood from flowing backwards
64
What are valves?
Foldings of the inner walls of the veins
65
Function of capillaries
Allow exchange of materials between blood and tissue
66
How are capillaries adapted for their function?
- Endothelium consists of a single layer of flattened cells and the walls are partially permeable
- Capillary network increases surface area and total cross sectional area for more efficient exchange of substances between blood and cells
67
How are useful materials and oxygen exchanged between capillaries and tissue cells?
By diffusion
| blood in blood capillaries → through the capillary walls → tissue fluid → cells
68
How are waste products exchanged between capillaries and tissue cells?
By diffusion
| cells → tissue fluid → through the capillary walls → blood in blood capillaries → excretory organs (for removal)
69
What is double circulation?
Blood passes through the heart twice as it moves from the pulmonary circulation and into the systemic circulation
70
What are the advantages of having a double circulation?
- Blood enters the pulmonary circulation at a low pressure, ensuring sufficient time for blood to be fully oxygenated before returning to the heart
- Blood is pumped into the systemic circulation at a high pressure, ensuring oxygenated blood is quickly distributed to all the tissues in the body
71
Structure of the heart: roughly ________ shape
conical
72
Structure of the heart: lies between ________ and behind ________
lungs
| chest-bone
73
Structure of the heart: Surrounded by ________
pericardium
74
Structure of the heart: consists of four ________: two ________ and two ________
chambers
atria
ventricles
75
Thickness of atria walls
relatively thinner walls to force blood into the ventricles
76
Thickness of right ventricle walls
relatively thick muscular walls to move blood into the pulmonary circulation
77
Thickness of left ventricle walls
thicker muscular walls than the right ventricle as it has to pump blood into the systemic circulation
78
What are the blood vessels associated with the heart?
```
pulmonary artery
pulmonary veins
pulmonary arch
aortic arch
superior (anterior) vena cava
inferior (posterior) vena cava
```
79
Pathway of blood through the heart (1)
Deoxygenated blood returns to the heart via the vena cava
80
Pathway of blood through the heart (2)
Right atrium contracts and blood flows into right ventricle
81
Pathway of blood through the heart (3)
Right ventricle contracts and blood leaves through pulmonary arch
82
Pathway of blood through the heart (4)
Blood leaves the heart and enters lungs via the pulmonary arteries
83
Pathway of blood through the heart (5)
Oxygenated blood from the lungs flows to left atrium via pulmonary veins
84
Pathway of blood through the heart (6)
Left ventricle contracts and blood flows towards aortic arch
85
Pathway of blood through the heart (7)
Blood leaves the heart via the aortic arch and is pumped to rest of body
86
Describe the cardiac cycle (1)
1. Both atria and ventricles are relaxed
2. The right and left atria are filled with blood from the vena cava and pulmonary veins respectively
3. Both atria contract, forcing blood into ventricles
87
Describe the cardiac cycle (2: ventricular systole)
1. The ventricles contract (ventricular systole) and the pressure in the ventricles rises
2. This results in closure of the bicuspid and tricuspid valves to prevent backflow of blood into the atria
3. A ‘lub’ sound is produced by the closure of these valves
4. When the pressure in the ventricles is higher than in the aorta, the semi-lunar valves in the aortic and pulmonary arches open
5. Blood enters the pulmonary and systemic circulation via the pulmonary arch and aortic arch respectively
6. As the ventricles contract, the atria relax
88
Describe the cardiac cycle (3: ventricular diastole)
1. When ventricles relax (ventricular diastole), the pressure in the ventricles falls
2. This results in closure of the semi-lunar valves in the pulmonary and aortic arches to prevent backflow of blood into the ventricles
3. A ‘dub’ sound is produced by the closure of these valves
4. Due to the decrease in ventricular pressure, the bicuspid and tricuspid valves open, allowing blood to enter the ventricles
5. The whole cycle then repeats again
89
What is blood pressure?
The force exerted by the blood on the walls of blood vessels
90
How is blood pressure measured?
Using a sphygmomanometer
91
What is the unit of measurement for blood pressure?
millimetres of mercury (mm Hg)
92
When is the arterial blood pressure highest?
During ventricular systole
93
When does the arterial blood pressure decrease?
During ventricular diastole
94
What is a pulse?
Rhythmic bulging of the artery walls with each heartbeat
95
What is are coronary arteries?
Arteries that lie on the outside of the heart and carry oxygenated blood to the muscles in the walls of the heart
96
What is coronary heart disease?
When the blood supply to the heart muscles are greatly reduced due to the occlusion or blockage of the coronary arteries
97
What is the sequence of events leading up to coronary heart disease?
→ Buildup of fatty substances on inner surfaces of coronary arteries (atherosclerosis)
→ Lumen of arteries is narrowed
→ Blood clot forms in artery (thrombosis)
→ Reduced blood flow to heart
→ Heart muscle cells receive reduced oxygen supply
→ May lead to a heart attack
98
Causes of coronary heart disease [4]
- A high-fat diet rich in cholesterol and saturated animal fats
- Emotional stress
- Smoking
- Sedentary lifestyle
99
Preventive measures against coronary heart disease [4]
```
- A healthy diet
: reduced intake of animal fats which can be replaced with polyunsaturated plant fats
: vegetables and fruits
- Proper stress management
- Avoid smoking
- Regular physical exercise
```
100
What is balloon angioplasty?
A technique used to dilate an area of arterial blockage with the help of a catheter that has an inflatable small sausage-shaped balloon at its tip
101
What is coronary bypass?
- A surgery that creates a new path for blood to flow to the heart
- A healthy piece of vein from the leg / artery from the chest or wrist is attached to the coronary artery, just above and below the narrowed area or blockage
- This allows blood to bypass the blockage
