1. Regulation of Breathing Should we worry if someone has a temper tantrum and says they are going to hold their breathe until they get their way?

2. Recap – Where are we coming from External respiration and internal respiration Gasses travel through the blood Gasses have different partial pressures in the blood depending on location Oxygen and carbon dioxide travel through the blood in different ways (what are these ways?)

3. Regulation of Respiration Two types of chemoreceptors are involved in regulation of respiration Chemoreceptors are receptors in our body that detect chemical change (such as pH change) One type detects carbon dioxide levels by sensing the change in pH levels The other type detects oxygen levels Carbon dioxide / pH chemoreceptors are the MAIN RECEPTORS TO REGULATE BREATHING

4. Carbon dioxide / acid chemoreceptors Located in the medulla oblongata Stimulated by high carbon dioxide and low pH levels The activated medulla oblongata signals diaphragm and rib muscles to increase breathing movements CONTINUED

5. Carbon dioxide / acid chemoreceptors Normal acidity range is 7.35 – 7.45 When blood is too acidic, rate of respiration increases to get rid of excess carbon dioxide. When blood is too basic, rate of respiration decreases to allow carbon dioxide levels to build up once again

7. Why Do We Have Oxygen Chemoreceptors? Oxygen chemoreceptors are needed during times when oxygen levels decrease but carbon dioxide levels do not change Can you think of an example where this happens? Examples are people at high altitudes and people that inhale carbon monoxide

8. Acidosis & Alkalosis Acidosis – an increased level of carbon dioxide results in the formation of carbonic acid. It is caused by conditions that interfere with gas exchange, such as pneumonia or emphysema Alkalosis – results when more than the usual amount of carbon dioxide is removed from the blood. It is caused by an increased respiration rate, such as anxiety and aspirin poisoning

9. Can we suffocate by holding out breath? People can deliberately hold their breath for a period of time, despite rising carbon dioxide levels in the blood However, once a person passes out, the medulla oblongata regains control and stimulates the breathing rate We can not suffocate ourselves by holding our breath!

10. Pause for Thought During mouth-to-mouth resuscitation, exhaled air is forced into the victim’s trachea. As you know, exhaled air contains higher levels of CO2 than atmospheric air. Would the higher levels of CO2 create problems or be beneficial? Provide your reasons.