w6- control of ventilation

Question 1

how do opoids result in respiratory depression

Answer 1

interfere with the ventillation pacemaker cells in the ventral medilla (Pre-Botzinger complex)

Question 2

what nerves supply cardiovascular and respiratory input to the dorsal medulla for inspiration

what kind of feedback do lung receptors and j receptors relay through the vagus nerve

Answer 2

• CN IX (Glossopharyngeal)
• CN X (Vagus)

lung strecth receptors

A-beta fibers (large, myelinated) –> lung receptors Provide feedback to terminate inspiration

j fibers

C-fibers (small, unmyelinated)

Provide feedback related to pulmonary congestion dyspnea, tachypnea, apnea

irritant receptors

coughing and sneezing

Question 3

outline the impact that hypoxemia has in the carotid bodies

Answer 3

Hypoxemia increases the ventilatory response to hypercapnia

Hypercapnia increases the ventilatory response to hypoxia

Low pH increases ventilatory responses to PCO2, PO2

–> all interplay

how it detects hypoxemia

1. When PO 2 decreases below around 60 mmHg, K+channels close
2. Closing K+ channels causes… cell depolarization!
3. Cell depolarization opens voltage-gated calcium channels
4. Calcium comes in down its gradients (concentration and electrical!), increasing cytosolic calcium
5. Transmitter release is initiated (ATP is likely the most important)
6. ATP binds to a purinergic receptor on afferent terminals of CN IX branch.
7. Activated afferent fibers increase action potentials to CNS respiratory centers
8. Respiratory centers stimulate breathing.

Question 4

name some thinsg that depress your ventillatory response to Co2

Answer 4

sleep

narcotics

Chronic obstruction (adaptation to hypercapnia PLUS increased work of breathing)

anesthesia