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exchange and mass transport Flashcards

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1
Q

Q: What is the surface area to volume ratio (SA:V) and why is it important?

A

A: It is the ratio of an organism’s surface area to its volume; a high SA:V allows faster diffusion relative to volume.

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2
Q

Q: Why do larger organisms need specialised exchange surfaces?

A

A: Because they have a small SA:V ratio and diffusion alone is too slow to meet metabolic needs.

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3
Q

Q: What are key features of efficient exchange surfaces?

A

A: Large surface area, thin (short diffusion distance), and good blood supply or ventilation.

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4
Q

Q: Give examples of specialised exchange surfaces in animals.

A

A: Alveoli in lungs, villi in intestines, gill lamellae in fish.

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5
Q

Q: How do single-celled organisms exchange gases?

A

A: By simple diffusion across their surface membrane.

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6
Q

Q: How do insects reduce water loss during gas exchange?

A

A: With a waterproof exoskeleton, spiracles that can close, and tracheae lined with chitin.

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7
Q

Q: What is the tracheal system in insects?

A

A: A network of air-filled tubes that deliver oxygen directly to tissues through diffusion.

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8
Q

Q: How is gas exchange achieved in fish?

A

A: Via gill filaments and lamellae using a counter-current flow mechanism.

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9
Q

Q: What is the counter-current system in fish and why is it efficient?

A

A: Blood and water flow in opposite directions across gill lamellae, maintaining a steep O₂ gradient for maximum diffusion.

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10
Q

Q: What adaptations do plant leaves have for gas exchange?

A

A: Stomata for diffusion, air spaces in the mesophyll, and a thin flat shape.

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11
Q

Q: How do xerophytes reduce water loss?

A

A: Thick cuticle, rolled leaves, sunken stomata, hairy leaves, fewer stomata.

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12
Q

Q: What is meant by ventilation in mammals?

A

A: The movement of air into and out of the lungs to maintain concentration gradients.

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13
Q

Q: What structures make up the human gas exchange system?

A

A: Trachea, bronchi, bronchioles, alveoli.

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14
Q

Q: How are alveoli adapted for gas exchange?

A

A: Thin walls (short diffusion pathway), large surface area, surrounded by capillaries for good blood supply.

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15
Q

Q: What happens during inspiration?

A

A: Diaphragm contracts and flattens, external intercostals contract, pressure in lungs falls, air is drawn in.

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16
Q

Q: What happens during expiration?

A

A: Diaphragm relaxes, internal intercostals contract (during forced expiration), pressure increases, air is forced out.

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17
Q

Q: How is pulmonary ventilation calculated?

A

A: Tidal volume × ventilation rate

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18
Q

Q: What is tidal volume?

A

A: The volume of air inhaled or exhaled in a single normal breath.

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19
Q

Q: What is the ventilation rate?

A

A: The number of breaths taken per minute.

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20
Q

Q: What is Fick’s Law and how does it apply to gas exchange?

A

A: Rate of diffusion ∝ (surface area × difference in concentration) ÷ thickness of exchange surface.

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21
Q

Q: How does asthma affect gas exchange?

A

A: Airways become inflamed and narrowed, reducing airflow and gas exchange efficiency.

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22
Q

Q: How does emphysema affect gas exchange?

A

A: Alveoli walls break down, reducing surface area and decreasing diffusion rate.

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23
Q

Q: How does tuberculosis affect gas exchange?

A

A: It causes lung tissue damage, scarring and reduces surface area for gas exchange.

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24
Q

Q: How does fibrosis affect gas exchange?

A

A: Scar tissue thickens alveolar walls, reducing elasticity and increasing diffusion distance.

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25
Q: How can lung diseases be diagnosed using spirometry?
A: By measuring lung volumes and capacities, e.g. FEV₁, FVC, and peak flow.
26
Q: What is FEV₁?
A: The volume of air forcibly exhaled in 1 second.
27
Q: What is FVC?
A: The maximum volume of air that can be forcibly exhaled after a deep breath.
28
Q: What is the FEV₁/FVC ratio used for?
A: To distinguish between obstructive and restrictive lung diseases.
29
What is the function of alveoli in the lungs?
To provide a large surface area for gas exchange.
30
How are alveoli adapted for gas exchange?
They have thin walls (one cell thick), a large surface area, and are surrounded by capillaries to maintain a steep concentration gradient.
31
What happens during inspiration?
Diaphragm contracts and flattens; external intercostal muscles contract; thoracic volume increases; pressure falls; air flows in.
32
What happens during expiration?
Diaphragm relaxes; internal intercostal muscles contract (forced expiration); thoracic volume decreases; pressure rises; air flows out.
33
What is pulmonary fibrosis?
Formation of scar tissue in lungs that thickens alveolar walls, reducing diffusion rate.
34
What is asthma and how does it affect gas exchange?
An allergic condition causing bronchoconstriction; narrows airways and reduces airflow.
35
What is emphysema?
Destruction of alveolar walls, reducing surface area for gas exchange.
36
What is the role of amylase?
Enzyme that breaks down starch into maltose in the mouth and small intestine.
37
What are endopeptidases and exopeptidases?
Endo cleave peptide bonds within proteins; exo remove terminal amino acids.
38
What is the function of lipase?
Hydrolyses triglycerides into fatty acids and glycerol.
39
What role do bile salts play?
Emulsify lipids, increasing surface area for lipase action.
40
How are monosaccharides absorbed into the bloodstream?
Via sodium-dependent co-transport in the ileum then facilitated diffusion into blood.
41
How are fatty acids and monoglycerides absorbed?
They form micelles, diffuse into epithelial cells, re-form triglycerides, and are transported in chylomicrons via lymph.
42
What is haemoglobin?
A quaternary protein in red blood cells that binds and transports O₂.
43
What is the oxygen dissociation curve?
A sigmoid graph showing saturation of haemoglobin vs. pO₂.
44
What is the Bohr effect?
Rightward shift of the dissociation curve at high CO₂ or low pH, promoting O₂ release in tissues.
45
What is a double circulatory system?
Blood passes through the heart twice per circuit: pulmonary and systemic circuits.
46
What separates the left and right sides of the heart?
The septum.
47
Describe atrial systole.
Both atria contract, pushing blood into the ventricles.
48
Describe ventricular systole.
Both ventricles contract, forcing blood into the pulmonary artery and aorta.
49
What happens during diastole?
All chambers relax, atria fill with blood returning via veins.
50
What prevents backflow of blood in the heart?
Valves: atrioventricular valves (tricuspid, bicuspid) and semilunar valves (pulmonary, aortic).
51
How is cardiac output calculated?
Cardiac output = stroke volume × heart rate.
52
What does 'myogenic' mean in reference to the heart?
The heart’s rhythm is initiated by muscle itself (SAN), not nerves.
53
What are the structural differences between arteries and veins?
Arteries have thicker muscle and elastic walls; veins have valves and thinner walls.
54
What is the role of arterioles?
To regulate blood flow into capillary beds by constricting or dilating.
55
What are capillaries adapted for exchange?
One-cell-thick walls, narrow diameter for slow flow, and large surface area.
56
What is tissue fluid?
Fluid that leaks from capillaries, bathing cells and returning via lymphatic vessels.
57
What causes atherosclerosis?
Build-up of fatty plaques in arteries, narrowing lumen and reducing blood flow.
58
Name major risk factors for cardiovascular disease.
High cholesterol, hypertension, smoking, obesity, and inactivity.
59
What safety precautions are needed in a heart dissection?
Wear gloves, goggles; tie back hair; use disinfected tools; dispose of tissue correctly.
60
What structures should be identified in a heart dissection?
Atria, ventricles, valves, coronary vessels, aorta, and pulmonary artery.
61
What are key rules for biological drawings?
Use a sharp pencil, no shading, label lines clear without arrowheads, draw to scale, and include magnification.
62
explain the formation of tissue fluid (3)
at the arteriole end of capillaries: 1. higher hydrostatic pressure inside capillaries (due to contraction of ventricles) than tissue fluid 2. forcing water (and dissolved substances) out of capillaries 3. large plasma proteins remain in capillary
63
explain the return of tissue fluid to the circulatory system (4)
at the venule end of capillaries: 1. hydrostatic pressure reduced as fluid leaves capillary 2. (due to water loss) an increasing concentration of plasma proteins lowers water potential in capillary below that of tissue fluid 3. water enters capillaries from tissue fluid by osmosis, down a water potential gradient 4. excess water taken up by lymph capillaries and returned to circulatory system through veins
64
what is an artery?
blood vessel that conveys blood under high pressure away from the heart
65
what are capillaries?
blood vessel that links arterioles and venules these are at the site of the formation of tissue fluid and the exchange of materials between the blood and body cells
66
what is elastic tissue?
a type of connective tissue consisting mainly of elastic fibres found in the skin, the lungs, and the walls of some blood vessels
67
what is endothelium?
cells that line body tubes that exchange materials with the internal environment, such as the blood vessels and the lymph vessels
68
what is hydrostatic pressure?
pressure exerted by a fluid in terms of blood, also known as blood pressure
69
what is lymph?
a slightly milky fluid found in lymph vessels and made up of tissue fluid, fats and lymphocytes
70
what is the lymphatic system?
part of the circulatory system, and a vital part of the immune system, comprising a network of lymphatic vessels that carry lymph from body tissues to the vena cava
71
what is tissue fluid?
fluid that surrounds the cells of the body its composition is similar to that of blood plasma, except that it lacks proteins it supplies nutrients to cells and removes waste products
72
what is ultrafiltration?
filtration assisted by blood pressure, e.g. in the formation of tissue fluid and glomerular filtrate
73
what is a vein?
blood vessel that conveys blood under low pressure towards the heart
74
explain how the gills of fish are adapted for has exchange (3)
- gills made of many filaments covered with many lamellae = increased SA for diffusion - thin lamellae walls, so short diffusion distance - lamellae have large number of capillaries - removal of O2 and brings CO2 quickly maintaining conc grad
75
what is coronary heart disease?
CHD is a condition where the coronary arteries (which supply blood to the heart muscle) become narrowed or blocked. This reduces blood flow and oxygen supply to the heart muscle, which can lead to heart attacks.
76
causes of coronary heart disease?
Atherosclerosis is the main underlying cause of CHD. It involves the build-up of fatty plaques inside the coronary artery walls. Plaques are made up of cholesterol, fats, white blood cells, and other debris. These plaques narrow arteries, reducing blood flow.
77
how does atherosclerosis develop?
Damage to the endothelium (inner lining of artery) due to factors like high blood pressure, smoking, or high blood cholesterol. White blood cells and lipids (fats) accumulate at the damaged site. This leads to fatty plaque formation and artery narrowing. Artery walls can also become less elastic, raising blood pressure and worsening the problem.
78
risk factors for CHD?
Uncontrollable: age, gender (men more at risk), genetics/family history. Controllable: High blood cholesterol ,High blood pressure (hypertension) Smoking (damages arteries, increases blood pressure) Poor diet (high in saturated fats, salt) Lack of exercise, Obesity, Stress, Diabetes
79
symptoms of Coronary heart disease
Chest pain (angina) due to reduced blood flow. Shortness of breath. Heart attacks (if a coronary artery is fully blocked).
80
consequences of coronary heart disease
Reduced oxygen supply to heart muscle → heart cells may die → heart attacks. Can lead to heart failure or arrhythmias.
81
prevention and treatment of coronary heart disease?
Lifestyle changes: healthy diet, regular exercise, quitting smoking, controlling weight. Medications: -Statins (reduce blood cholesterol) -Antihypertensives (lower blood pressure) -Anticoagulants/antiplatelets (reduce clotting) -Surgical treatments

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