Mass transport In humans

Question 1

Describe the blood flow in the heart

Answer 1

Deoxygenated blood returns from body in vena cava and enters right atrium

Blood passes via atrioventricular valve into right ventricle and out via semilunar valve into pulmonary artery

Blood now passed through lines and returns to left atrium via pulmonary vein

Blood passes through second atrioventricular valve into left ventricle and through semi lunar valve into aorta and then to body tissues

Question 2

Name the 3 stages of cardiac cycle

Answer 2

1) Atrial systole
2)ventricular systole
3)diastole

Question 3

Explain how an arteriole can reduce blood flow into the capillaries

Answer 3

1. muscles contracts
2. constricts / narrows arteriole / lumen

Question 4

Describe how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta

Answer 4

1. Atrium has higher pressure than ventricle
2. Atrioventricular valves opens
3. Ventricle has higher pressure than atrium
4. Atrioventricular valve closes
5. Ventricle has higher pressure than aorta
6. Semi lunar valve opens
7. Higher pressure in aorta than than ventricle
8. Semi lunar valve closes
9. Muscle contraction causes increase in pressure

Question 5

How does pressure change in the capillaries?

Answer 5

Increased cross-sectional area
- causes increased friction -> which reduces blood pressure
- flow changes from pulsar to smooth and speed of flow decreases

Question 6

Describe blood flow in the aorta (3)

Answer 6

• Flow is fast
• Pressure is high
  (and fluctuating/pulsar)
• Due to the contraction of the left ventricle

Question 7

Explain how one feature of an alveolus allows efficient gas exchange to occur.
[2 marks]

Answer 7

1. (The alveolar epithelium) is one cell thick;
2. Creating a short diffusion pathway /
   reduces the diffusion distance;

Question 8

Describe how the movement of the diaphragm leads to air movement into the lungs

Answer 8

1) Diaphragm contracts and flattens
2) Volume of lungs increases
3) Pressure inside the lungs is lower than atmospheric pressure
4) Air moves into the lungs

Question 9

Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs.
Do not include descriptions of pressure changes in the heart or the role of heart valves in your answer. (3 marks)

Answer 9

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

Question 10

Tissue fluid is formed from blood at the arteriole end of a capillary bed.
Explain how water from tissue fluid is returned to the circulatory system (4 marks)

Answer 10

1. (Plasma) proteins remain;
   Accept albumin/globulins/fibrinogen for (plasma)
   protein
2. (Creates) water potential gradient
   OR
   Reduces water potential (of blood);
3. Water moves (to blood) by osmosis;
4. Returns (to blood) by lymphatic system;

Question 11

ways to improve scientific drawing

Answer 11

1. Only use single lines/do not use sketching (lines)/ensure lines are
   continuous/connected;
2. Add labels/annotations/title;
3. Add magnification/scale (bar);
4. Draw all parts to same scale/relative size;
5. Do not use shading/hatching;

Question 12

differences between Vein and Artery

Answer 12

• Vein: larger lumen, thinner muscle layer
• Artery: smaller lumen, thicker muscle layer