Unit 6.4

Question 1

Physiological respiration definition?

Ventilation definition?

Gas exchange definition?

Cell respiration definition?

Answer 1

Involves the transport of oxygen to cells within the tissues, where energy production occurs.

The exchange of air between the atmosphere and the lungs - achieved by the physical act of breathing.

The exchange of oxygen and carbon dioxide between the alveoli and bloodstream.

The release of energy from organic molecules - it is enhanced by the presence of oxygen.

Question 2

1. Why is a ventilation system needed?
2. How many lobes is the right lung composed of?
3. How many lobes is the left lung composed of?
4. Where does gas exchange occur?
5. what are the 4 specialized structures of alveoli?

Answer 2

1. Maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries.
2. 3 lobes
3. 2 lobes
4. The alveoli
5. They are folded - increases surface area.
   Have a capillary network - maintains concentration gradient.
   One cell thick - short diffusion distance.
   Moist - allows gasses to dissolve quickly.

Question 3

1. Name the cells that line the alveoli.
2. What are the 2 types of cell?
3. Describe type 1 (4 factors)
4. Describe type 2 (4 factors)

Answer 3

1. Pneumocytes
2. Type 1 and Type 2
3. Squamous and extremely thin, cover 95% of alveolar surface, involved in gas exchange, 1 cell thick.
4. Granular and roughly cuboidal, cover 5% alveoli surface, secrete pulmonary surfactant, 1 cell thick.

Question 4

1. Function and purpose of type 1 pneumocytes?
2. How are they connected?
3. 1 factor involving their replication?

Answer 4

1. Involved in gas exchange in alveoli and capillaries, thin so minimise diffusion distance.
2. Occluding junctions to prevent leakage of tissue fluid into the alveolar air space.
3. Amitotic and unable to replicate.

Question 5

1. Function and purpose of type 2 pneumocytes?
2. Explain process of the surfactant.
3. Why do they have a granule shape?
4. Why are alveoli lined in a layer of liquid?
5. Limitation of moist lining?
6. What is surface tension?

Answer 5

1. Secretion of pulmonary surfactant to reduce surface tension in alveoli for equal rate of inflation.
2. Alveoli expands - surfactant spreads across moist alveolar lining - increases surface tension, slows rate of expansion - this ensures all alveoli inflate at same rate.
3. lots of ribosomes as surfactant is made from a protein.
4. easier for oxygen to diffuse across alveoli and capillary membrane when dissolved.
5. Creates a tendency for the alveoli to collapse and resist inflation.
6. The elastic force created by a fluid surface that minimises the surface area.

Question 6

1. What does the mechanism of breathing occur according to?
2. When volume in thoracic cavity increases, pressure in what decreases?
3. When volume in thoracic cavity decreases, pressure in what increases?
4. Inspiration process?
5. Expiration process?
6. Assisting muscle groups during inspiration?
7. Assisting muscle groups during expiration?

Answer 6

1. The Principle of Boyle’s Law
2. Pressure in thorax decreases
3. Pressure in thorax increases
4. Diaphragm contract and flatten, increases volume in thoracic cavity. External intercostal muscles contract pull rips upwards + outwards to expand chest.
5. Diaphragm relaxes, curves upwards in dome shape, reduce volume in thoracic cavity. Intercostals relax, pull ribs down + inwards - reduces breadth of chest.
6. Sternocleidomastoid and pectoralis minor.
7. Quadratus lumborum.

Question 7

1. What do abdominal muscles do during forced exhalation?
2. What is Boyle’s law?
3. When pressure in the chest is less than atmosphere pressure, where does air move?
4. What does high altitude cause?
5. Lung cancer is?
6. 2 reasons for lung cancer being the largest cause of cancer related death worldwide.

Answer 7

1. Contract and push the diaphragm upwards.
2. Pressure (P) = 1/ Volume As volume increases, pressure decreases. As volume decreases, pressure increases.
3. Air moves into lungs (and vice versa)
4. Atmospheric pressure is low, so greater increase in chest volume required before pressure differential is formed.
5. Uncontrolled proliferation of lung cells, leading to the abnormal growth of lung tissue (tumour).
6. 1: lung are vital to body function so their abrogation is detrimental.
   2: Posses a rich blood supply, increasing likelihood of cancer spreading.

Question 8

1. Lung cancer symptoms
2. If the cancer mass compresses adjacent organs it causes:
3. 6 causes of lung cancer
4. Emphysema is?
5. Main emphysema cause?
6. Why is this?

Answer 8

1. Coughing up blood, wheezing, respiratory distress, weight loss.
2. Chest pain, difficulty swallowing, heart complications.
3. Smoking, pollution, genes, ageing, radiation, asbestos.
4. Lung condition where alveoli walls lose elasticity due to damaged walls. This leads to abnormal enlargement causing lower total surface area for gas exchange. This can cause holes so alveoli merge into huge air spaces.
5. Chemical irritants in cigarettes from long term smoking.
6. Smoking damages alveolar walls, brings phagocytes to the region, they produce an enzyme called elastate, breaks down elastic fibres in the alveolar walls.

Question 9

1. What is a small proportion of emphysema caused by?
2. Emphysema symptoms?
3. Changes in blood CO2 levels are detected by?
4. How does exercise influence ventilation?
5. 3 ways ventilation can be monitored?
6. What does a spirometer do?

Answer 9

1. Hereditary deficiency in enzyme inhibitor a-1-antitrypsin due to a gene mutation.
2. Phlegm, lethargic, bluing tips of finger and lips, likely chest infections.
3. Chemosensors in arterial walls which send signals to brain.
4. Increase ventilation rate and tidal volume.
5. Counting breaths per min, chest belt and pressure meter, spirometer.
6. A device that detects the changes in ventilation and presents the data on a digital display.