Mammalian Respiratory System (Med Sci)

Which gas is taken into the blood from the alveoli during gas exchange?

• Oxygen

• Carbon Dioxide

• Nitrogen

• Helium

Answer explanation

During gas exchange in the alveoli, oxygen is taken in from the air we breathe. This oxygen is essential for cellular respiration, while carbon dioxide is expelled as a waste product.

Which gas is expelled from the alveoli during gas exchange?

• Carbon dioxide

• Oxygen

• Nitrogen

• Helium

Answer explanation

During gas exchange in the alveoli, oxygen is absorbed into the blood while carbon dioxide, a waste product of metabolism, is expelled from the body. Therefore, the correct answer is carbon dioxide.

What is the function of elastic fibres in the alveoli?

• Absorb oxygen

• Recoil to expel stale air

• Transport blood

• Filter impurities

Answer explanation

Elastic fibres in the alveoli allow the lungs to recoil after inhalation, helping to expel stale air efficiently. This function is crucial for maintaining effective gas exchange.

What does ventilation of the lungs supply and remove?

• Supplies carbon dioxide rich air and removes oxygen rich air

• Supplies oxygen rich air and removes carbon dioxide rich air

• Supplies nitrogen rich air and removes oxygen rich air

• Supplies oxygen rich air and removes nitrogen rich air

Answer explanation

Ventilation is essential for breathing; it supplies oxygen to the body and removes carbon dioxide, a waste product of metabolism. Therefore, the correct answer is that it supplies oxygen and removes carbon dioxide.

What ensures erythrocytes are pushed against the capillary wall?

• Large diameter of capillary

• Small diameter of capillary

• High blood pressure

• Low blood pressure

Answer explanation

The small diameter of capillaries forces erythrocytes to travel in single file, pushing them against the capillary wall. This close contact facilitates efficient gas exchange and nutrient delivery.

What type of cells form the capillary endothelium and squamous epithelium?

• Cuboidal cells

• Columnar cells

• Single flattened cells

• Stratified cells

Answer explanation

The capillary endothelium and squamous epithelium are composed of single flattened cells, known as simple squamous epithelium. This structure allows for efficient exchange of materials due to its thinness.

Oxygen is used for which of the following purposes?

• Aerobic respiration

• Photosynthesis

• Protein synthesis

• DNA replication

Answer explanation

Oxygen is essential for breathing and cellular respiration, where it is used to produce energy in cells. The other options, such as photosynthesis, protein synthesis, and DNA replication, do not directly require oxygen.

Describe the pathway of an oxygen molecule through the following structures: Nasal passage, Pharynx, Larynx, Trachea, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Squamous epithelial cell (alveolus wall), Capillary endothelial cell (capillary wall), Blood plasma, Red blood cell.

• Nasal passage, Pharynx, Larynx, Trachea, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Squamous epithelial cell, Capillary endothelial cell, Blood plasma, Red blood cell

• Nasal passage, Larynx, Pharynx, Trachea, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Squamous epithelial cell, Capillary endothelial cell, Blood plasma, Red blood cell

• Nasal passage, Pharynx, Trachea, Larynx, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Squamous epithelial cell, Capillary endothelial cell, Blood plasma, Red blood cell

• Nasal passage, Pharynx, Larynx, Trachea, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Capillary endothelial cell, Squamous epithelial cell, Blood plasma, Red blood cell

Answer explanation

The correct pathway for an oxygen molecule is: Nasal passage, Pharynx, Larynx, Trachea, Bronchus, Bronchiole, Alveolus, Water lining alveolus, Squamous epithelial cell, Capillary endothelial cell, Blood plasma, Red blood cell.

What are the features of a specialized exchange surface? Adaptations to maximize diffusion rates include:

• Large surface area

• Short diffusion path

• Steep concentration gradients (supply and removal of molecules)

• All of the above.

Answer explanation

Specialized exchange surfaces have adaptations that maximize diffusion rates, including a large surface area, a short diffusion path, and steep concentration gradients. Therefore, the correct answer is 'All of the above.'

Fill in the blank: One of the adaptations to maximize diffusion rates in a specialized exchange surface is a ________ diffusion path.

Answer explanation

A short diffusion path minimizes the distance that molecules must travel, enhancing the efficiency of diffusion. This is crucial for specialized exchange surfaces, such as in lungs or gills, where rapid gas exchange is needed.