Control of Ventilation

Question 1

Central controllers of the respiratory control system

Answer 1

Pons, medulla, other parts of the brain

Question 2

Respiratory effectors

Answer 2

Diaphragm

Intercostal muscles

Sternocleidomastoids

Scalene muscles

Abdominals

Nasopharyngeal muscles

Question 3

Sensors of the respiratory control system

Answer 3

Central and peripheral oxygen and chemoreceptors

Question 4

Breathing can be voluntarily controlled from the ____ along w input from the __ and __

Answer 4

cerebral cortex

limbic system & hypothalamus

Question 5

Brainstem respiratory controls

Answer 5

Medulla respiratory center

Apneustic center

Pneumotaxic center in the upper pons

Question 6

Diving reflex

Answer 6

Heart rate slows when you immerse your face in cold water and hold your breath

This preferentially distributes O₂ stores to the heart and brain to allow staying underwater for longer.

Question 7

The diving reflex can be used to break

Answer 7

supraventricular tachycardia

(because it slows the heart down; very strong in babies)

Question 8

What respiratory variable can cross the bloodbrain barrier and stimulate central chemoreceptors?

Answer 8

CO₂

_{(O2 does cross, but there is no response to hypoxia in the central chemoreceptors)}

Question 9

Why are there more rapid changes in pH of CSF compared to blood?

Answer 9

There’s no hemoglobin.

So when CO₂ reacts w H₂O in cerebrospinal fluid, there is less buffering capacity.

Question 10

What are the peripheral chemoreceptors?

How do they respond to changes in oxygen?

What factors change the sensitivity of peripheral chemoreceptors?

Answer 10

• Glomus cells, type I and II
• Non-linear response to low O_2, responds maximally when pO2 is less than 50
• Increased CO₂ & acidic conditions (increased H+) increases the response

Question 11

List the lung receptors that provide sensory input to the breathing centers

Answer 11

• Stretch receptors: smooth muscle cells send input to brain via vagus nerve
• Irritant receptors between airway epithelial cells
• Pulmonary J receptors: juxtacapillary, in the alveolar walls
• Bronchial C fibers: stimulates bronchoconstriction and mucus secretion

Question 12

What are the non-pulmonary receptors that provide sensory input to breathign centers?

Answer 12

• Irritant receptors in the nose and upper airway
  
  • ​Induces coughing & sneezing
• Joint & muscle receptors: stimulates respiratory increase in exercise
• Gamma system of stretch receptors: in the intercostals; controls strength of contraction
• Arterial baroreceptors:
  
  • ​increase ventilation when low bp
  • decrease ventilation when hypertension
• Increased pain & temp increases ventilation

Question 13

What is the most important stimulus to ventilation usually?

The central ventilatory response is magnified if the ____ level is low.

Answer 13

Arterial CO

Central ventilatory response is magnified if the arterial O2 is low

Question 14

Most of the stimulus to breathe coems from the __ chemoreceptors, but the ___ chemoreceptors’ response is faster

Answer 14

Most = central

Faster = peripheral

Question 15

What will DECREASE ventilatory response to CO₂?

Answer 15

• Sleep, age genetics, racial diferences, personality, athletic fitness, perceived work of breathing
• Benzodiazepines and opioids

Question 16

Metabolic acidosis ___creases the ventilation response to CO₂

Answer 16

Metabolic acidosis causes the body to push the equation to the left –> ventilation increases –> lowers blood pCO2

It increases the response to carbon dioxide

Question 17

Describe the changes in ventilation, blood CO2, and O₂ that occur with normal vs intense exercise?

Answer 17

Dramatic increase in ventilation

• Normal exercise - arterial pO2, pCO2, and pH normal
• Intense exercise
  
  • Arterial pCO2 falls
  • Alveolar pO2 rises (bc above), arterial pO2 falls
  • pH falls slightly due to lactic acidosis

Question 18

Cheyne-Strokes respiration

Answer 18

10-20 second periods of apnea followed by equal periods of hyperventilation when the tidal volume gradually waxes and then wanes

Occurs during sleep, high altitudes, heart failure, brain disease/ injury

Question 19

How does heart failure cause Cheyne-STrokes respiration?

How does stroke or brain injury do it?

Answer 19

Heart failure: delay in the feedback loop between blood carbon dioxide level, the brain, and the respiratory effector muscles due to decreased cardiac output

Stroke or brain injury: an injury to the central respiratory controllers in the brainstem.