Topic 2 The Respiratory System: Control of Respiration

Question 1

• The medulla oblongata is the major player in this scenario which signals the diaphragm to contract

Answer 1

Control of Respiration

Question 2

1. When partial pressure of CO2 increases, medulla stimulates and increase in rate of ventilation
2. Diaphragm, skeletal muscle innervated by the phrenic nerve, is signaled to contract
   a. Diaphragm: only organ all mammals have
3. When lungs inflate, thoracic pressure decreases as thoracic cavity increases
   - This repeats giving us a steady breathing rate
   - This contains central chemoreceptors, and the heart contains peripheral chemoreceptors that constantly monitor the body:
4. Central Chemoreceptors: indirectly monitor [H+] in the cerebrospinal fluid
5. Peripheral Chemoreceptors: located in carotid arteries and aorta and function to monitor atrial concentrations of CO2, O2, and pH via H+
   - In active body, there is increased CO2 production which enters plasma and is converted to HCO3- and H+
   - The blood supply subsequently drops and the respiratory rate increases

Answer 2

Medulla Oblongata

Question 3

• The majority of CO2 in the blood is transported in the form of bicarbonate (HCO3-). To a lesser extent it can be transported bound to hemoglobin/plasma proteins, and to an even lesser extent, simply dissolved in the plasma. CO2 is significantly more soluble in blood than O2.

Answer 3

Note