BMS130 Lecture Notes - Lecture 2: Internal Intercostal Muscles, Thoracic Cavity, Peripheral Chemoreceptors
RESPIRATORY SYSTEM
Central chemoreceptor's
- Located in the medulla
- Reacts to changes in the pH of cerebrospinal fluid
- ↑ed H+ concentration in CSF is a potent stimulus for ↑ing the respiratory rate
Peripheral chemoreceptor's
- Located in the aortic and carotid bodies
- Reacts to changes in the concentration of CO2 and O2 in the blood
- ↑ CO2 may directly stimulate peripheral chemoreceptors and trigger ↑ ventilation
more quickly than central chemoreceptors
- O2 levels need to drop considerably (< 60 mm Hg) to have any effect on
respiration
Irritant receptors
- Located in the respiratory mucosa
- Reacts to the presence of irritants, causes bronchoconstriction or cough
Stretch receptors
- Located in the smooth muscle of the bronchi and the visceral pleura
- Responds to excessive inflation triggers to stop inspiration
- Limbic system and hypothalamus respiratory effects of pain and emotion
Explain how pressure gradients account for flow in and out of the lungs, and
explain how these pressure gradients are produced
1. Boyle’s Law: at a constant temperature, pressure is inversely proportional to
volume
2. Charles's Law: at a given pressure, the volume of a given quantity of gas is
directly proportional to it’s temperature
Remember: Air moves DOWN the gradient from high to low pressure
- Atmospheric pressure (PB) drives respiration
- All other pressures are reported relative to PB
Inspiration
1. VRG Inspiratory Neurons cause diaphragm and intercostals contraction via the
phrenic and intercostal nerves respectively
→Increases the volume of the thorax
2. The increase in thoracic volume causes a decrease in intrapulmonary pressure
to -3 mm Hg (i.e.. 3 mm Hg lower than atmospheric pressure)
3. Intrapulmonary pressure is 3 mm Hg lower than atmospheric pressure
→ Air flows down the pressure gradient
Document Summary
Reacts to changes in the ph of cerebrospinal fluid (cid:313)ed h+ concentration in csf is a potent stimulus for (cid:313)ing the respiratory rate. Reacts to changes in the concentration of co2 and o2 in the blood (cid:313) co2 may directly stimulate peripheral chemoreceptors and trigger (cid:313) ventilation more quickly than central chemoreceptors. O2 levels need to drop considerably (< 60 mm hg) to have any effect on respiration. Reacts to the presence of irritants, causes bronchoconstriction or cough. Located in the smooth muscle of the bronchi and the visceral pleura. Responds to excessive inflation triggers to stop inspiration. Limbic system and hypothalamus respiratory effects of pain and emotion. Remember: air moves do n the gradient from high to low pressure. All other pressures are reported relative to pb. Intrapulmonary pressure is 3 mm hg lower than atmospheric pressure. 3. (cid:314) air flows down the pressure gradient: air flows from the atmosphere into the lungs.
