6.4 Gas Exchange

Coloring Activity – 15 minutes

6.4.1

Ventilation The process of moving air into and out of the lungs. It involves muscular movement and requires energy. It maintains a concentration gradient so that oxygen can continue diffusing into the blood. It keeps the oxygen concentration higher in the lungs than in the blood.

6.4.5 Ventilation – 2 steps Inspiration Expiration

With a partner… Try to figure out what happens each time you inhale and exhale. Determine what happens to each of the following: volume of lungs Muscles around the ribcage Diaphragm Pressure in the lungs

Inspiration The external intercostal muscles contract and move the ribcage up and outward. The diaphragm contracts, flattening it downward. Both actions have the effect of increasing the volume of the chest cavity. As the volume increases, the pressure decreases and the air flows into the lungs

Expiration The external intercostal muscles relax and the ribcage moves back down. The internal intercostal muscles contract. The diaphragm relaxes, moving it back up. Both actions have the effect of decreasing the volume of the chest cavity. As the volume decreases, the pressure increases and the air flows out of the lungs

6.4.2 Why is a ventilation system necessary? 1. To maintain a concentration gradient so that gas exchange can occur. To keep SA:V ratio high so that diffusion can occur.

The Respiratory System

Pharynx vs. Larynx

6.4.1 Gas Exchange The movement (diffusion) of oxygen from the air in the lungs into the blood AND carbon dioxide in the opposite direction. There are two sites for gas exchange 1. Alveoli: Oxygen diffuses into the blood from the alveoli and carbon dioxide diffuses from the blood into the alveoli 2. Tissues: Oxygen diffuses from blood into the cells and carbon dioxide diffuses from cells to the blood

Draw this! 6.4.1

6.4.3 Alveoli Four features of alveoli allow efficient gas exchange Large surface area Thin – things can diffuse quick Moist – gases dissolve before passing through membranes Good blood supply – maintains the concentration gradient

How many membranes must an oxygen molecule pass through in order to enter a erythrocyte?

Cell Respiration The cellular process of releasing energy from food (large organic molecules). In the presence of oxygen, 1 glucose molecule yields 36 ATP molecules

Ventilation (V), gas exchange (GE) and cell respiration(CR) are all dependent on each other. V requires energy provided by CR. GE depends on a concentration gradient provided by V. CR is more efficient in the presence of oxygen which relies on GE

VentilationGas ExchangeCell Respiration Where Energy Physical or Chemical Process? 6.4.1

Diagram

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Asthma

6.4.4 Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli.