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Biology - Module 3 > Topic 3.2 - Transport In Animals > Flashcards

Topic 3.2 - Transport In Animals Flashcards

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1
Q

Why do multicellular animals require specialised transport system?

A

Due to factors such as size, metabolic rate, and surface area to volume ratio

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2
Q

How does the size of an organism affect its need for a specialised transport system?

A

As organisms increase in size, the distance between their internal cells and the external environment grows. This increased distance makes diffusion alone insufficient for transporting substances like oxygen and nutrients to all cells efficiently.

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3
Q

What is the significance of surface area to volume ratio (SA: V) in relation to transport systems in animals?

A

Larger animals have a smaller SA: V ratio; this reduced ratio limits the amount of substances that can diffuse across their body surfaces to meet the needs of their larger volumes. Consequently, diffusion is inadequate for the effective exchange of gases and nutrients in larger organisms

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4
Q

How does metabolic rate influence the need for a transport system in multicellular organisms?

A

They typically exhibit higher metabolic rates, necessitating greater oxygen and nutrient intake and increased waste removal. The demands of a high metabolic rate cannot be met solely through diffusion, making specialised transport systems essential.

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5
Q

What is an open circulatory system?

A

An open circulatory system is when blood, or haemolymph, is not contained in blood vessels. Instead, it is pumped by the heart into a body cavity called the haemocoel, where it directly bathes tissues and organs

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6
Q

How does haemolymph move and exchange substances in an open circulatory system?

A

The heart pumps haemolymph into the haemocoel, and from there, it flows freely through the body, exchanging gases, nutrients, and waste products through direct diffusion

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7
Q

What happens to the haemolymph after circulation in an open circulatory system?

A

Once it has circulated through the body, the haemolymph returns to the heart

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8
Q

Why is the pressure low in an open circulatory system?

A

Since the haemolymph is not confined to blood vessels, the pressure within the system is low, and the flow of haemolymph is slower and less directed compared to closed circulatory systems

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9
Q

Why is an open circulatory system less efficient at transporting substances?

A

The system is less efficient because of the low pressure and the lack of precise control over the haemolymph flow

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10
Q

What is a closed circulatory system?

A

In a closed circulatory system, the blood is enclosed in blood vessels and does not come directly into contact with the cells of the body

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10
Q

How does blood move in a closed circulatory system?

A

The heart pumps blood around the body under pressure and quickly, and the blood returns directly to the heart

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11
Q

How do substances enter and leave the body in a closed circulatory system?

A

Substances leave and enter the body by diffusion through the walls of the blood vessels

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12
Q

How can blood flow be controlled in a closed circulatory system?

A

The amount of blood flowing to a particular tissue can be adjusted by widening or narrowing the blood vessel

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12
Q

What is a single closed circulatory system?

A

A single closed circulatory system is when blood passes through the heart once per circuit. The blood passes through two sets of capillaries (microscopic blood vessels) before it returns to the heart

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13
Q

What is the process of circulation in a single closed circulatory system?

A
  1. Deoxygenated blood from the body enters the atrium of the heart
  2. The atrium contracts and sends the deoxygenated blood into the ventricle
  3. The ventricle contracts, pumping the deoxygenated blood through the artery to the gills, where gas exchange occurs, and oxygen is absorbed.
  4. Oxygenated blood is then transported via the aorta to the rest of the body
  5. As blood travels through the body, it exchanges oxygen for carbon dioxide and other waste products from tissues.
  6. The deoxygenated blood is then returned to the heart, where the cycle begins again.
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14
Q

What is an advantage of a single closed circulatory system in fish?

A

Efficient transport in aquatic environments. For fish, the low system is sufficient because they do not need to transport blood quickly across long distances

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15
Q

Why does a single circuit require less energy?

A

A single circuit is simple and reequires less energy to maintain than more complex system

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15
Q

What is a disadvantage of single closed circulatory system in terms of pressure?

A

Lower circulation pressure: The low pressure in the system results in slower blood flow, limiting the speed at which substances are delivered and removed from tissues.

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16
Q

Why does a single closed circulatory system limit organism size and activity levels?

A

As the blood pressure is low, the system is not suitable for larger, more metabolically demanding organisms that require higher circulation rates

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17
Q

What type of animals have a double-closed circulatory system?

A

This system is found in more complex animals, including mammals, birds, and amphibians, and provides a more efficient transport of oxygen and nutrients compared to a single closed system

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18
Q

What is the process of circulation in a double-closed circulatory system?

A
  1. The body’s tissue returns deoxygenated blood to the right atrium of the heart
  2. The right atrium contracts and sends the deoxygenated blood through the pulmonary artery to the lungs, where it becomes oxygenated
  3. The right ventricle contracts, sending the blood through the pulmonary artery to the lungs, where it becomes oxygenated
  4. The oxygenated blood returns to the heart through the pulmonary veins, entering the left atrium
  5. The left atrium contracts and pumps the oxygenated blood into the aorta from where it is distributes to the rest of the body
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19
Q

What is an advantage of a double-closed circulatory system in terms of pressure and speed?

A

Higher pressure and faster circulation: the double pass through the heart allows for higher pressure in the systemic circuit, resulting in faster blood flow and quicker delivery of oxygen and nutrients

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20
Q

How does a double-closed circulatory system allow for efficient gas exchange?

A

By separating oxygenated and deoxygenated blood, the system ensures that oxygenated blood is delivered efficiently to tissues, while deoxygenated blood is sent to the lungs for oxygenation.

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21
Q

Why is a double-closed- circulatory system suitable for larger, more active organisms?

A

The higher pressure and more efficient transport make this system suitable for larger animals with higher metabolic rated, such as mammals and birds

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22
How does a double-closed circulatory system provide greater control over circulation?
The separation of pulmonary and systemic circuits allow for better control of the blood flow to specific areas of the body, depending on the body's needs
23
What is a disadvantage of the double-closed circulatory system in terms of complexity?
A double-closed circulatory system is more complex than a single-closed system and requires more energy to maintain, due to the need for higher pressure and more intricate structure
24
What is a disadvantage of a double-closed circulatory system regarding risk?
With a more complex system, there is an increased risk of circulatory failure if part of the system, such as a valve or vessel becomes damaged
25
What are arteries adapted for?
Arteries carry blood away from the heart under high pressure. They have thick walls with elastic tissue to stretch and recoil, smoothing blood flow. Smooth muscle allows control over blood flow, and a smooth endothelium reduces friction
26
How do arteries smooth blood flow?
Elastic tissue allows them to stretch and recoil in response to pressure changes, which help smooth out the flow of blood
27
How do arteries vary blood flow?
Smooth muscle in the artery walls can contract or relax to regulate the amount of blood flowing through
28
What is the function of the smooth endothelium in arteries?
It reduces friction and eases the flow of blood
29
What is the function of arterioles?
Arterioles distribute blood from arteries to capillaries and regulate blood flow via vasoconstriction and vasodilation
30
How are arterioles structurally different from arteries?
Arterioles have more smooth muscle and fewer elastic fibres, and the have a smaller diameter
31
How do arterioles control blood flow to specific tissues?
By contracting or relaxing their smooth muscle, they can reduce or increase blood flow to particular areas
32
What is the function of capillaries?
Capillaries enable the exchange of gases, nutrient, and waste between the blood and surrounding tissues
33
What are the structural features of capillaries that aid exchange?
Capillaries have walls made of a single layer of endothelial cells, gaps between cells from small molecule passage, and a narrow diameter to slow blood flow and maximise exchange time
34
Why do capillaries have no smooth muscle, collagen, or elastic fibres?
These components are unnecessary as capillaries are specialised for diffusion and exchange, not for withstanding pressure or regulating flow
35
What is the function of venules?
Venules collect blood from capillaries and deliver it to veins. They may also allow some exchange, particularly of white blood cells.
35
What is the structure of venules?
Venules have thin walls with a thin layer of smooth muscle and collagen, and a larger lumen than arterioles
36
What is the function of veins?
Veins return blood to the heart under low pressure
37
How are veins structurally adapted to low-pressure blood flow?
Veins have thin walls with little elastic tissue or smooth muscle, and they contain valves to prevent backflow due to the lack of pulse pressure
38
What is tissue fluid?
Tissue fluid is a liquid derived from blood plasma that surrounds cells in tissues and enables the exchange of gases, nutrients, and waste
39
Explain the formation of tissue fluid from plasma
1. At the arterial end of capillaries, blood is under high hydrostatic pressure due to the heart’s contraction 2. This pressure forces water and small molecules (e.g., oxygen, glucose, amino acids) out of the blood plasma through tiny gaps in the capillary walls into the surrounding tissue 3. Large plasma proteins and blood cells are too big to pass through, so they stay in the blood 4. The remaining proteins in the blood create an oncotic pressure (a pulling force due to low water potential), which opposes the movement of fluid out 5. However, at the arterial end, hydrostatic pressure is greater than oncotic pressure, so net movement is outwards, forming tissue fluid 6. At the venous end, hydrostatic pressure falls, but oncotic pressure remains. So water moves back in by osmosis 7. Excess tissue fluid that doesn’t re-enter the blood is drained into the lymphatic system and eventually returned to the bloodstream.
40
How is lymph fluid different from plasma and tissue fluid?
Lymph has less oxygen and fewer nutrients but contains fatty acids absorbed from the small intestine
41
How is lymph transported and filtered?
Lymph is transported through lymphatic vessels and filtered through lymph nodes, which remove pathogens and debris
41
Where does lymph re-enter the circulatory system?
Lymph drains into the subclavian veins near the heart
42
What type of muscle makes up the heart?
Cardiac muscle
42
What is the role of the pericardium?
It is a protective membrane surrounding the heart
43
What are the coronary arteries and what is their function?
Coronary arteries are blood vessels on the heart's surface that supply oxygenated blood to the cardiac muscle
44
Why does the cardiac muscle require a blood supply?
To receive oxygen for respiration, enabling contraction and continuous pumping
45
What is the apex of the heart made of?
The thick muscular wall of the left ventricle
46
Name the four major blood vessels entering and leaving the heart?
- Aorta - Pulmonary Artery - Pulmonary Veins - Vena Cava
47
What is the function of the aorta?
Carries oxygenated blood from the left ventricle to the body
48
What is the function of the pulmonary artery?
Carried deoxygenated blood from the right ventricle to the lungs
49
What is the function of the pulmonary veins?
Bring oxygenated blood from the lungs to the left atrium
50
What is the function of the vena cava?
Brings deoxygenated blood from the body into the right atrium
51
Why is the left ventricle wall thicker than the right?
It generates higher pressure to pump blood around the entire body
52
What is the role of the atrioventricular valves?
Prevent backflow of blood into the atria during ventricular contraction
53
What valve is between the right atrium and right ventricle?
Tricuspid valve
54
What valve is between the left atrium and left ventricle?
Bicuspid valve
55
What are tendinous cords and their function?
They anchor atrioventricular valves to the ventricles and prevent them from inverting under pressure
56
What are semilunar valves are where are they found?
Valves at the base of the arteries leaving the heart: the pulmonary valve (pulmonary artery) and aortic valve (aorta)
57
What is the function of semilunar valves?
Prevent backflow of blood into the ventricles after contraction
58
What is the septum and its function?
A muscular wall that separates the left and right sides of the heart to prevent mixing of oxygenated and deoxygenated blood
59
What happens during atrial diastole?
Atria are relaxed and fill with blood from the vena cava and pulmonary veins; ventricles also begin to fill passively
60
What happens during atrial systole?
Atria contract, increasing pressure and pushing blood through atrioventricular valves into ventricles
61
What happens during ventricular systole?
Ventricles contract, closing atrioventricular valves and opening semilunar valves; blood is pumped into the pulmonary artery and aorta
62
What happens during ventricular diastole?
Ventricles relax, semilunar valves close, and atria being refilling with blood from the body and lungs
63
What does it mean when cardiac muscle is described as myogenic?
It means the heart muscle can initiate its own contractions without external nerve stimulation
64
What is the function of the Sino-Atrial Node (SAN)?
The SAN acts as the heart's natural pace maker by generating regular electrical impulses that trigger atrial contraction
65
Where is the SAN located?
In the wall of the right ventricle, near the opening of the vena cava
66
What happens when the SAN generates an impulse?
It causes both atria to contract (atrial systole), pushing blood into the ventricles
67
What is the function of the Atrio-Ventricular Node (AVN)?
It delays the electrical signal from the SAN to ensure the atria have time to fully contract before the ventricles contract
68
Where is the AVN located?
At the junction between the atria and the ventricles
69
What is the Bundle of His and its function
A bundle of purkinje fibres in the septum that conducts the electrical impulse from the AVN to the base of the ventricles
70
What is the role of Purkinje tissue?
It rapidly transmits the impulse from the bundle of His to the ventricular walls, causing coordinated ventricular contraction (ventricular systole)
71
Why is the delay at the AVN important?
It allows time for the atria to fully contract and empty before the ventricles contract
71
What is an electrocardiogram (ECG)?
A non-invasive test that records the electrical activity of the heart over time using electrodes placed on the skin
71
What ensures the rhythmic, automatic beating of the heart?
The myogenic nature of cardiac muscle and the regular electrical impulses initiated by the SAN
72
What does an ECG detect?
Electrical impulses generated by the heart muscle during the cardiac cycle
73
What can the shape and timing of ECG waves indicate?
They can be used to assess heart function, rhythm, strength, and coordination of electrical activity
74
What does the P wave represent?
Atrial depolarisation - when the atria contract and push blood into the ventricles
75
What does the QRS complex represent?
Ventricular depolarisation - when the ventricles contract to pump blood to the lungs and body
76
What does the T wave represent?
Ventricular repolarisation - when the ventricles relax and prepare for the next cardiac cycle
77
How can abnormalities in an ECG be useful diagnostically?
Changes in wave shape, amplitude, or timing can indicate issues like arrythmias, heart enlargement, or past heart attacks
78
What is tachycardia and how is it identified on an ECG?
Tachycardia is a heart rate over 100 bpm. On and ECG, it shows frequent, closely spaced wave. It can be normal, or due to electrical issues in the heart
79
What is bradycardia and what might cause it?
Bradycardia is a heart rate below 60 bpm. It is often seen in fit individuals but can be serious, sometimes requiring a pacemaker. On ECG, waves are spaced far apart
80
What is an ectopic heartbeat and how is it seen on an ECG?
An ectopic heartbeat is an extra, irregular beat outside the normal rhythm. On ECG, it appears as an early beat with a disrupted pattern. It is usually harmless unless frequent
81
What is atrial fibrillation, and how does it affect ECG readings?
Atrial fibrillation is irregular, rapid electrical activity in the atria, seen as an irregular baseline with no clear P waves. It leads to inefficient blood pumping
82
Why might atrial fibrillation reduce cardia output?
Because the atria contract very rapidly and ineffectively, fewer impulses reach the ventricles, and less blood is pumped overall
83
What is the structure of haemoglobin and how does it relate to its function?
Haemoglobin is a quaternary protein made of four polypeptide chains (2 alpha, 2 beta), each with a haem group containing Fe²⁺. Each haem can bind one O₂, so one Hb molecule carries 4 O₂ molecules. Its structure allows reversible oxygen binding for loading and unloading.
83
Define oxygen loading and where it occurs.
Oxygen loading is when O₂ binds to haemoglobin in the lungs, where pO₂ is high. Haemoglobin has high oxygen affinity here, and cooperative binding makes O₂ uptake more efficient.
84
Define oxygen unloading and explain the conditions in which it occurs.
Oxygen unloading is when oxyhaemoglobin releases O₂ in respiring tissues where pO₂ is low. Increased CO₂ and H⁺ ions (from carbonic acid) lower haemoglobin's affinity for O₂, promoting its release.
85
What is cooperative binding in haemoglobin
It refers to how the binding of one O₂ molecule to haemoglobin increases its affinity for the next O₂ molecule, due to a conformational change in its structure.
86
Describe the shape and significance of the oxygen dissociation curve
The curve is S-shaped (sigmoidal) due to cooperative binding. It shows that haemoglobin loads O₂ efficiently at high pO₂ (e.g. lungs) and unloads it readily at low pO₂ (e.g. tissues).
87
What is the Bohr shift and how does it help in oxygen delivery?
The Bohr shift is the rightward shift of the oxygen dissociation curve at high CO₂ levels. It reduces haemoglobin’s oxygen affinity, promoting oxygen release in active tissues.
88
Compare fetal and adult haemoglobin in terms of oxygen affinity.
Fetal haemoglobin has a higher affinity for O₂ than adult haemoglobin. This enables the fetus to absorb O₂ from maternal blood across the placenta, where pO₂ is relatively low.
89
How is CO₂ transported in the blood and what enzyme is involved?
CO₂ enters red blood cells and forms carbonic acid (H₂CO₃), catalysed by carbonic anhydrase. H₂CO₃ dissociates into H⁺ and HCO₃⁻. H⁺ binds to haemoglobin (forming haemoglobinic acid), facilitating oxygen unloading.
90
What is the role of haemoglobinic acid in CO₂ transport?
Haemoglobinic acid forms when H⁺ ions (from dissociated carbonic acid) bind to haemoglobin. This helps buffer blood pH and promotes oxygen unloading.

Biology - Module 3 (3 decks)

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