6.4 Gas Exchange/Ventilation

(http://ibbio.pbworks.com/f/1305621458/alveolus.jpg)

Interesting links:

‪Gas Exchange During Respiration‬

http://www.youtube.com/watch?v=EFCj9STCvdI

Pressure Changes during Breathing‬

http://www.youtube.com/watch?v=ZvTdc1nAuBo&feature=related

The Lungs and Pulmonary System

http://www.khanacademy.org/science/biology/human-biology/v/the-lungs-and-pulmonary-system

6.4.5 Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostals muscles, the diaphragm and abdominal muscles

Ventilation consists of inhalation and exhalation.

Inhalation:

When a person breathes in, or inhales, the external intercostals muscles contract, making ribcage move up and out. The diaphragm contracts and flattens. This makes the thorax increase in volume; hence the pressure decreases inside the thorax. The volume of the lungs and alveoli also increase. Pressure eventually drops below atmospheric pressure, so air flows into the body through the mouth or nose, trachea, bronchi and bronchioles.

Exhalation:

When a person breathes out, or exhales, the intercostals muscles contract, making the ribcage move down and in. The abdominal muscles contract, pushing the diaphragm down and back to its original shape. This makes the volume of the thorax decrease; hence the pressure increases inside the thorax. The volume of the lungs and alveoli also decrease. Pressure eventually rises above atmospheric pressure, so air flows out of the lungs through nose or mouth to go out of the body.

(http://click4biology.info/c4b/6/hum6.4.htm)

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

(http://www.ibguides.com/biology/notes/gas-exchange-)

6.4.3 Describe the features of alveoli that adapt them to gas exchange

·      Great quantity increases surface area for gas exchange

·      Spherical shape to increase surface area

·      Surrounded by capillaries

·      Surface is moist to make diffusion easier

·      One celled layer to allow faster diffusion

·      Membranes are short, which result in a short distance for diffusion

(http://1.bp.blogspot.com/aUWSNlVi7N4/T7pGJHOvYqI/AAAAAAAABpk/2OSjn9gxVck/s1600/alveoli.png)

6.4.2 Explain the need for a ventilation system

Ventilation is needed to take in fresh air into the lungs, remove carbon dioxide from the body, which is a product of cell respiration, and to maintain concentration of oxygen and carbon dioxide inside the body. Also, the body needs oxygen to make ATP through cell respiration.

(http://www.normalbreathing.com/images-new/O2-normal.bmp)

6.4.1 Distinguish between ventilation, gas exchange and cell respiration

Ventilation is the process of inhaling (breathing in) and exhaling (breathing out) air, which is controlled by the diaphragm and the ribcage, or intercostals muscles.

  

Gas exchange is the diffusion of oxygen and carbon dioxide between the alveoli and the capillaries surrounding it. There are two steps: first oxygen diffuses into the capillaries from the alveoli and carbon dioxide diffuses out of the capillaries into the alveoli, second the oxygen diffuses from the blood in the capillaries into the cells and carbon dioxide diffuses out of the cell into the blood. 

All diagrams: (http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookrespsys.html)

Cell respiration is what happens within the cell for the production of ATP. There is aerobic respiration, which uses oxygen, and anaerobic, which does not.

(http://www.phschool.com/science/biology_place/biocoach/images/cellresp/Overview.gif)