Bio Revision Mr Webber

Question 1

Ventilation -Inhalation

Answer 1

During inspiration, the external intercostal muscles contract whereas the internal ones relax, as a result cause the ribs to raise upwards. The diaphragm contracts and flattens. In combination, the intercostal muscles and diaphragm cause the volume inside the thorax to increase, thus lowering the pressure. The difference between the pressure inside the lungs and atmospheric pressure creates a gradient, thus causing the air to enter the lungs.

Question 2

Ventilation -Exhalation

Answer 2

During expiration, the internal intercostal muscles contract whereas the external ones relax therefore lowering the rig cage. The diaphragm relaxes and rises upwards. These actions in combination decrease the volume inside the thorax, therefore increasing the pressure, forcing the air out of the lungs.

Question 3

What is a spirometer

Answer 3

A spirometer is a device used to measure lung volume. A person using a spirometer breathes in and out of the airtight chamber, thus causing it to move up and down, leaving a trace on a graph which can then be interpreted.

Question 4

Vital Capacity

Answer 4

The maximum volume of air that can be inhaled or exhaled in a single breath. Varies depending on gender, age, size as well as height

Question 5

Tidal volume

Answer 5

the volume of air we breathe in and out at each breath at rest

Question 6

Breathing rate

Answer 6

the number of breaths per minute, can be calculated from the spirometer
trace by counting the number of peaks or troughs in a minute

Question 7

Ventilation- Bony Fish

Answer 7

Ventilation is required to maintain a continuous unidirectional flow. Ventilation begins with the fish opening its mouth followed by lowering the floor of buccal cavity, thus enabling water to flow into it. Afterwards, fish closes its mouth, causing the buccal cavity floor to raise, thus increasing the pressure. The water is forced over the gill filaments by the difference in pressure between the mouth cavity and opercular cavity. The operculum acts as a valve and pump and lets water out and pumps it in.

Question 8

Insects

Answer 8

Insects do not possess a transport system therefore oxygen needs to be transported directly to tissues undergoing respiration. This is achieved with the help of spiracles, small openings of tubes, either bigger trachea or smaller tracheoles, which run into the body of an insect and supply it with the required gases. At the end of each tracheole is a small amount of tracheal fluid which allows gasses to dissolve and then diffuse into the cells.
Spiracles can be opened and closed to avoid excessive water loss
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Question 9

Gill features that make them efficient for gas exchange

Answer 9

• lots of Gill filaments, covered with lamellae which means it has a large surface area
• Thin layers in the lamellae which equal a short diffusion distance
• Continuous flow of water, means continual refreshing of oxygenated water which will maintain the gradient
• Continuous flow of blood through a rich network of capillaries
• Filament overlap and fan out, means more contact with water for exchange
• They have a countercurrent flow system which means there will be a constant gradient as the oxygenated water can diffuse into the blood at a constant rate.

Question 10

How is tracheal fluid withdrawn during periods of high oxygen demand?

Answer 10

• oxygen diffuse into the moisture of the walls and the tracheal fluid
• when the insect is moving, lactic acid builds up in the tissue resulting in the moisture and tracheal fluid moving out of the tracheal by osmosis
• this exposed more surface area for gas exchange