1. Chapter 12 Pg. 284 Respiratory System

2. Functions The functions of the respiratory system are: Brings air from the atmosphere into the lungs. Transfers O 2 into the blood. Removes CO 2 from the blood. Expels heat and water vapour (in the air breathed out). Allows the vocal cords to create speech (as air is breathed out).

3. Structure

4. Mechanics of Breathing Breathing: the movement of air into and out of the respiratory system in order to extract oxygen from the atmosphere and bring it into the body Each minute you breathe you move approx 7-8L of air in and out of your lungs. The design of the lungs, blood and blood system ensure that oxygen is absorb into the bloodstream and pump around the body by the heart.

5. Breathing in: inspiration The diaphragm* contracts and move downwards making the chest cavity larger. As the chest cavity becomes larger, the air pressure inside it becomes lower, sucking air in. Breathing out: expiration The diaphragm relaxes and the chest cavity goes back to its ‘resting’ size. Breathing out is a passive process but last longer than breathing in. The intercostal* muscles also aid the process by allowing the ribs to return to their ‘resting’ position. *Diaphragm is an involuntary muscle *Intercostal muscles are found between the ribs. Structure

7. Respiration and Exercise When you begin to exercise you use more energy from your body, which comes from the combination of oxygen and food stored in the cells. Therefore, when exercising you need to breathe more rapidly and more deeply.

8. Respiration Rate – the amount of times you breathe per minute (avg. 12-18 times/min) Tidal Volume – the amount of air breathed in and out with each breath (avg. 0.5L) Ventilation – amount of air breathed in per minute = tidal volume x respiratory rate 0.5L x 15 breaths = 7.5L Vital Capacity – the maximum amount of air you can breathe out after breathing in

9. Respiration and Exercise: Respiration will increase immediately – up to 35 times/minute. As you exercise, the level of CO 2 in your body increases. Your brain detects this and stimulates the increase in your respiratory rate. Tidal volume will increase from 0.5L up to 5L per breath. Ventilation will increase from 7.5L up to 150L per minute.

10. VO 2 Max V=Volume, O 2 =Oxygen The maximum amount of oxygen that can be breathed in, transported to, and used by your working muscles. A good measure of aerobic endurance (how efficient your circulatory, respiratory and muscular systems are whilst exercising). The actual figure is the largest amount of oxygen you can use per minute and is determined by your maximum heart, stroke volume and arteriovenous oxygen difference. Page 289, table 12.1

11. Passageway of Air Air breathed in through nostrils Air passes through your pharynx At the end of the pharynx there are 2 openings: one leads to the larynx, the other to the oesophagus. Air travels down the larynx, food travels down the oesophagus. Air then passes into the trachea (windpipe) which then divides into 2 bronchi, which then branch into bronchial tubes. Air moves through the bronchial tubes, which are part of the lungs. The bronchial tubes branch into smaller bronchioles, which connect to the alveoli.

12. Gaseous exchange: O 2 and waste transfer Gaseous exchange = The transfer of oxygen through the alveoli to the red blood cells. Oxygen passes rapidly through the lining of the alveoli and into the red blood cells in the capillaries, which add oxygen to the blood. Carbon dioxide is removed from the blood and enters the alveoli.