respiration 5

Question 1

Functional units of the respiratory system, why

Answer 1

Neurons

- Network and emergent properties

Question 2

Network and emergent properties of neurons

Answer 2

• Neurons form circuits creating infinite nr of
  possible pathways
• Signaling within these pathways: enables
  complex behaviors such as thinking,
  learning, memory, control of patterns
• Combination of neurons possesses
  emergent properties not found at single-
  cell level

Question 3

Dorsal horn

Answer 3

Cell bodies of interneurons on which afferent neurons terminate

Question 4

lateral horn

Answer 4

Cell bodies of autonomic efferent nerve fibres

Question 5

ventral horn

Answer 5

cell bodies of somatic efferent neurons

Question 6

__________ in brain stem establish a _______ breathing pattern

Answer 6

Respiratory centers

rhythmic

Question 7

nuclei

Answer 7

Clusters of nerve cell bodies in CNS

Question 8

ganglion

Answer 8

Clusters of nerve cell bodies in PNS

Question 9

Dominates over apneustic center (also an overdrive centre)

Answer 9

Medullary respiratory center

Question 10

Mostly inspiratory neurons

Answer 10

Dorsal respiratory group (DRG)

[of medullary respiratory center]

Question 11

Ventral respiratory group (VRG)

[ of Medullary respiratory center]

Answer 11

Inspiratory neurons
Expiratory neurons
Overdrive mechanism
Active respiration

Question 12

Pons respiratory center:

Answer 12

Apneustic center:
- Prevents inspiratory neurons from being
switched off
- Provides extra boost to inspiratory drive

Pneumotaxic center (breaks):
- Sends impulses to DRG that help “switch 
  off” inspiratory neurons

Pneumotaxic center > apneustic center
Without the breaks: long inspiration, short expiration = apneustic breathing

Question 13

Widely believed to generate respiratory rhythm
Self-induced action potentials (pace maker-like activity)
Driving the dorsal respiratory group (DRG)

Answer 13

Pre-Bötzinger complex

Question 14

Triggered to prevent overinflation of the lungs
When tidal volume > 1000ml (eg exercise)
Pulmonary stretch receptors
Afferent to medulla to inhibit inspiratory neurons
diving

Answer 14

Hering-Breuer reflex

Question 15

Arterial PO2 is monitored in

Answer 15

peripheral chemoreceptors.

The carotid bodies are located in the carotid sinus, and the aortic bodies are located in the aortic arch.

Question 16

What is the expected PO2 in the blood bathing the peripheral chemoreceptors

Answer 16

Only sensitive below 60 mmHg, no major role in normal respiration!

Question 17

Arterial PO2 control

Answer 17

Question 18

__________ for H+ are the main control mechanism for respiration.
[monitor CO2]

Answer 18

Central chemoreceptors

measure CO2 in cerebrospinal fluid

Question 19

increase in PCO2 in the arterial blood (increase in H+ in the brain ECF)

Answer 19

• weakly stimulates peripheral
  chemoreceptors
• strongly stimulates central
  chemoreceptors; dominant control of
  ventilation [Levels > 70-80 mm Hg]

Question 20

Chemical factors that play role in determining magnitude of ventilation

Answer 20

• PO2: peripheral receptors, but only when
  drastic changes
• PCO2: weak response via peripheral
  receptors
  > Carbon dioxide generated H+: main
  regulator for respiration

Question 21

Factors That Influence Ventilation That Are Unrelated to Need for Gas Exchange

Answer 21

• Protective reflexes such as sneezing and
  coughing
• Inhalation of noxious agents which can
  trigger immediate cessation of breathing
• Pain originating anywhere in body reflexly
  stimulates respiratory center
• Involuntary modification of breathing
  occurs during expression of various
  emotional states
• Respiratory center is reflexly inhibited
  during swallowing

Question 22

Hyperventilation

Answer 22

• Faster + deeper breathing than normal
• Emotional control
• PO2 normal
• Co2 increased –> vasoconstriction
  Alkalosis clamping, higher affinity to O2 in Hg!
  Tingle, numbness, dizziness, spasms in hands

Question 23

Factors That May Increase Ventilation During Exercise

Answer 23

Reflexes originating from body movement
Increase in body temperature
Epinephrine release
Impulses from the cerebral cortex