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Biology > Topic 3E: The Mammalian Circulatory System > Flashcards

Topic 3E: The Mammalian Circulatory System Flashcards

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1
Q

Explain how the highest blood pressure is produced in the left ventricle. [1]

A
  1. Stronger contractions
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2
Q

Some babies are born with a hole between the right and left ventricles. These babies are unable to get enough oxygen to their tissues.

Suggest why. [2]

A
  1. Blood flows from left ventricle to right ventricle;
  2. Lower volume of (oxygenated) blood leaves left ventricle
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3
Q

Suggest how tendinous cords help to maintain the flow of blood in one direction through the heart. [2]

A
  1. (Valves close) when ventricles contract;
  2. Prevent valves from being inverted
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4
Q

Give two safety precautions that should be followed when dissecting a heart. [1]

A
  1. Use a sharp scalpel;
  2. Wash hands/wear gloves;
  3. Disinfect bench;
  4. Cover any cuts;
  5. Cut away from self/on a hard surface;
  6. Safe disposal by placing hearts in separate bin
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5
Q

Explain how atrioventricular valves help to maintain a unidirectional flow of blood. [2]

A
  1. Pressure in atrium is higher than in ventricle causing valve to open;
  2. Pressure in ventricle is higher than in atrium causing valve to close
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6
Q

Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs. [3]

A
  1. Renal vein;
  2. Vena cava to right atrium;
  3. Right ventricle to pulmonary artery
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7
Q

Name the blood vessels that carry blood to the heart muscle. [1]

A
  1. Coronary arteries
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8
Q

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta. [5]

A
  1. Atrium has higher pressure than ventricle causing atrioventricular valves to open;
  2. Ventricle has higher pressure than atrium causing atrioventricular valves to close;
  3. Ventricle has higher pressure than aorta causing semilunar valve to open;
  4. Higher pressure in aorta than ventricle causing semilunar valve to close;
  5. (Muscles) contraction causes increase in pressure.
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9
Q

Suggest how the flow of some of the blood between the aorta and pulmonary artery due to Patau syndrome could cause children to die in the first 12 months. [3]

A
  1. (Some) oxygenated blood (from aorta) flows into pulmonary artery;
  2. Less oxygen delivered to cells;
  3. So less oxygen for aerobic respiration;
  4. Tissue dies
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10
Q

The cardiac cycle is controlled by the sinoatrial node (SAN) and the atrioventricular node (AVN).

Describe how. [5]

A
  1. SAN sends wave of electrical activity (across atria) causing atrial contraction;
  2. Non-conducting tissue prevents impulses reaching the ventricles;
  3. AVN delays (impulse) whilst ventricles fill;
  4. (AVN) sends wave of electrical activity down Bundle of His;
  5. Causing ventricles to contract from base up
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11
Q

Describe and explain the structure of arteries. [6]

A
  1. Lumen: space through which blood flows;
  2. Endothelium: smooth to reduce friction with blood;
  3. Elastic tissue: stretches due to high blood pressure when ventricle contracts then recoils when ventricle relaxes;
  4. This recoil help to maintain blood pressure and smooth blood flow;
  5. Muscle: contracts to constrict the lumen (vasoconstriction);
  6. Reduces blood flow
  7. Outer layer: tough to withstand high blood pressure and stop bursting;
  8. The aorta and pulmonary artery have semilunar valves to prevent back flow of blood into the ventricles.
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12
Q

State the structural differences between arteries and veins. [2]

A
  1. Narrow lumen vs wide lumen;
  2. More elastic tissue vs less elastic tissue;
  3. More muscle vs less muscle;
  4. Thicker wall vs thinner wall;
  5. No valves vs valves
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13
Q

Explain how arteries can reduce the blood flow to certain parts of the body. [2]

A
  1. Contracts;
  2. (Causing) vasoconstriction
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14
Q

Explain how elastic tissue in the walls of arteries help to even out the pressure of blood. [2]

A
  1. Stretches when pressure is high;
  2. Recoils to normal
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15
Q

Describe and explain the structural adaptations of capillaries. [5]

A
  1. Endothelium is one cell thick so diffusion pathway is short;
  2. Endothelium cells are flattened so diffusion pathway is short;
  3. Narrow lumen increases friction and therefore reduces rate of blood flow so there is more time for diffusion;
  4. Narrow lumen means red blood cells are in close contact with the endothelium so diffusion pathway for oxygen is short;
  5. Small diameter overall so large surface area to volume ratio;
  6. Pores between endothelial cells allow water and certain dissolved substances to leak out of blood and form tissue fluid.
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16
Q

Explain why the rate of blood flow decreases from the aorta to the capillaries. [1]

A
  1. Increases in friction
17
Q

Efficient exchange of substances in the capillaries is linked to the rate of blood flow.

Explain how. [1]

A
  1. (More) time for exchange of substances
18
Q

Explain how an arteriole can reduce the blood flow into capillaries. [2]

A
  1. Muscle contracts;
  2. Narrows lumen
19
Q

Which blood vessel carries blood with the lowest pressure? [1]

A
  1. Vena cava
20
Q

Describe two precautions a student should take when clearing away after a dissection. [2]

A
  1. Carry sharp instruments by the handle;
  2. Disinfect surfaces;
  3. Wash hands with soap (and water);
  4. Put organ in a (separate) bin to dispose
21
Q

Describe how tissue fluid is formed and how it is returned to the circulatory system. [6]

A

Formation:
1. High blood pressure;
2. forces water out;
3. Large proteins remain in capillary;

Return:
4. Low water potential in blood;
5. Due to proteins;
6. Water enters blood;
7. (by) osmosis
8. (Any remaining excess) tissue fluid returns (to blood) via lymphatic system.

22
Q

Explain the role of the heart in the formation of tissue fluid. [2]

A
  1. Contraction of ventricle(s) produces high blood pressure;
  2. Forces water (and some dissolved substances) out (of blood capillaries)
23
Q

Suggest how a blockage in the lymphatic system could cause swelling. [1]

A
  1. Excess tissue fluid builds up
24
Q

Explain why a lack of protein in the blood causes a build up of tissue fluid. [3]

A
  1. Water potential gradient is reduced;
  2. Less water removed (into capillary);
  3. By osmosis
25
Q

The hydrostatic pressure of the blood at the arteriole end of the capillary helps to form tissue fluid.

Explain how. [2]

A
  1. Hydrostatic pressure higher than osmotic effect;
  2. Forces water out
26
Q

A high concentration of sodium ions in the blood can raise blood pressure. Suggest how. [3]

A
  1. (Sodium ions) lower the water potential (of blood);
  2. Water moves into the blood by osmosis (from tissue fluid);
  3. Increasing the blood volume
27
Q

What is the function of the coronary arteries? [2]

A
  1. (Carry) oxygen/glucose;
  2. (to) heart muscle
28
Q

The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why. [3]

A
  1. Directly linked to the heart;
  2. (Aorta has) elastic tissue;
  3. Stretch / recoil
29
Q

Although the speed of blood flow in an arteriole is greater than speed of blood flow in a capillary, blood does not accumulate in the arterioles.

Explain why. [1]

A
  1. Many capillaries;
  2. (Cross-sectional) area of capillaries (much) greater
30
Q

An arteriole is described as an organ. Explain why. [1]

A
  1. Made of (different) tissues
31
Q

Explain the difference in thickness between the pulmonary artery and the pulmonary vein. [1]

A
  1. Higher pressure in pulmonary artery
32
Q

The thickness of the aorta wall changes all the time during each cardiac cycle.

Explain why. [3]

A
  1. (Wall) stretches because pressure increases;
  2. Recoils because pressure falls;
  3. Maintains pressure/smooth flow
33
Q

Describe and explain the changes in the speed of flow of blood from the aorta to capillaries. [2]

A
  1. Slow decrease in speed until reaches arterioles then rapid decrease;
  2. More friction
34
Q

Explain why the volumes of blood in the pulmonary artery and vein are the same but the speed of flow is different. [1]

A
  1. (Pulmonary vein has) wider lumen so greater volume carried
35
Q

Describe how you would calculate cardiac output from heart rate and stroke volume. [1]

A

Heart rate x stroke volume

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