respiration 5 Flashcards
Functional units of the respiratory system, why
Neurons
- Network and emergent properties
Network and emergent properties of neurons
- 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
Dorsal horn
Cell bodies of interneurons on which afferent neurons terminate
lateral horn
Cell bodies of autonomic efferent nerve fibres
ventral horn
cell bodies of somatic efferent neurons
__________ in brain stem establish a _______ breathing pattern
Respiratory centers
rhythmic
nuclei
Clusters of nerve cell bodies in CNS
ganglion
Clusters of nerve cell bodies in PNS
Dominates over apneustic center (also an overdrive centre)
Medullary respiratory center
Mostly inspiratory neurons
Dorsal respiratory group (DRG)
[of medullary respiratory center]
Ventral respiratory group (VRG)
[ of Medullary respiratory center]
Inspiratory neurons
Expiratory neurons
Overdrive mechanism
Active respiration
Pons respiratory center:
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
Widely believed to generate respiratory rhythm
Self-induced action potentials (pace maker-like activity)
Driving the dorsal respiratory group (DRG)
Pre-Bötzinger complex
Triggered to prevent overinflation of the lungs
When tidal volume > 1000ml (eg exercise)
Pulmonary stretch receptors
Afferent to medulla to inhibit inspiratory neurons
diving
Hering-Breuer reflex
Arterial PO2 is monitored in
peripheral chemoreceptors.
The carotid bodies are located in the carotid sinus, and the aortic bodies are located in the aortic arch.
What is the expected PO2 in the blood bathing the peripheral chemoreceptors
Only sensitive below 60 mmHg, no major role in normal respiration!
Arterial PO2 control
__________ for H+ are the main control mechanism for respiration.
[monitor CO2]
Central chemoreceptors
measure CO2 in cerebrospinal fluid
increase in PCO2 in the arterial blood (increase in H+ in the brain ECF)
- weakly stimulates peripheral
chemoreceptors - strongly stimulates central
chemoreceptors; dominant control of
ventilation [Levels > 70-80 mm Hg]
Chemical factors that play role in determining magnitude of ventilation
- PO2: peripheral receptors, but only when
drastic changes - PCO2: weak response via peripheral
receptors
> Carbon dioxide generated H+: main
regulator for respiration
Factors That Influence Ventilation That Are Unrelated to Need for Gas Exchange
- 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
Hyperventilation
- 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
Factors That May Increase Ventilation During Exercise
Reflexes originating from body movement
Increase in body temperature
Epinephrine release
Impulses from the cerebral cortex
