Lecture 19 respiratory system Flashcards
Why study respiration?
Essential for life: Provides O2 and removes CO2 to ensure correct cellular functioning (gas exchange).
Breathing is the basis for multiple critical behaviours: speaking, olfaction, emesis (vomiting).
Strong links to emotional centers in the brain.
Terminology notes
Respiration = ventilation = breathing Inspiration = a breath in Expiration = breathing out
Describe the main function of the respiratory system.
See other cards
Discuss the brainstem regulation of breathing and stimuli that influence breathing.
See other cards
Discuss the brainstem regulation of breathing and stimuli that influence breathing.
See other cards
How gas exchange occurs
Fresh air (21% O2, ~0.05% CO2) enters the lungs during inspiration.
The low O2 and high CO2 blood entering the lungs from the body has the O2 replenished and CO2 removed by diffusion in the alveoli.
The high CO2/low O2 (~13% O2, ~5% CO2) air is breathed out of the lungs during expiration.
SUPPLEMENT YOUR BIO KNOWLEDGE
Respiratory system anatomy
see illustration in slides
Difference between inspiration and expiration
Inspiration
Active, diaphragm and intercostal muscle activation.
Expiration
Passive at rest, relies on recoil of the lungs/chest wall.
Active during exercise/stress using abdominal muscles.
there is a graph
Need to learn the areas of your spinal cord
LEARN IT!
Neural innervation
Phrenic nerves innervate diaphragm. Cervical spinal cord (C3-C5). Intercostal nerves innervate intercostal muscles. Thoracic spinal cord (T1-T11). Accessory muscles (abdomen for example) activated during high work/cough. Lumbar spinal cord.
What brain strucutres are responsible for controlling breathing
and where are they anatomically
The main respiratory pattern generator (pacemaker) is located in the Pre Botzinger complex.
The region of the brain that responds to CO2 is the retrotrapezoid nucleus (RTN also called parafacial respiratory group - pFRG).
O2 and CO2 are also sensed in the peripheral arteries and these signals are sent to the RTN via nerves.
There is a difference between dorsal and ventral groups
i don’t remember
Inputs to the respiratory centres
Peripheral
Chemosensors: through the RTN
Lung irritant and stretch: through DRG
Inputs to the respiratory centres
Central (supramedullary): primarily via PRG Volitional, Pain, Temperature, Emotion Speech, Swallow, Cough, Sneeze, Hiccup Sleep, Exercise, Defecation, Parturition Panting, sonar (animals)
Emotions and respiratory control
Amygdala – Pontine respiratory group (PRG) connection such that emotional stimuli result in respiratory rate increase.
Amygdala – DRG connection that results in inspired volume (and cardiovascular) increase.
Fear/anger: increase respiratory rate and sometimes depth
Positive affect: slow and deep (excited) or shallow (calm)
Bi-directional links: Basolateral amygdala (and hypothalamus) also CO2 sensitive.
Panic Disorder
Defined as: frequent, unexpected acute panic attacks
Panic attack: episode (~30min) of overwhelming anxiety and distress with:
Air hunger, shortness of breath, Hyperventilation
Low CO2 symptoms
ABDOMEN:nausea, cramping
CONSCIOUSNESS:dizziness, fainting, confusion, disorientation
HEART:palpitations, increased rate, angina symptoms, arrhythmias
MUSCLES:spasm, weakness, fatigue
PERIPHERAL CHANGES:trembling, shivering, sweatiness, coldness, tingling, and numbness;
SENSES:blurred vision, dry mouth, sound seems distant, reduced pain threshold;
RESPIRATION:shortness of breath, bronchial constriction/spasm, feelings of suffocation, air hunger
VASCULAR:hypertension, migraine, palor
Respiratory findings in Panic Disorder
Suffocation “false alarm” hypothesis
Heightened responsiveness to CO2
Increased sigh frequency
Increased central apnea in sleep
cycle of stress and overbreahting see graph in slides
how to cope with panic attacks
breathe back your carbon dioxide
paper bag, cover your mouth
Breath holding spells
Involuntary breath holding in toddlers during a tantrum/when very upset.
The turn blue, can pass out and have a seizure.
Prevalence ~ 5% of toddlers.
The emotional input to the respiratory controller is very strong!
Dyspnea and mood
Dyspnea is a term for the discomfort associated with being short of breath/breathless.
Sharma JAP 2015
20 healthy adults did 6 x 5 minute exercise tests (brisk steep walk) on 3 days while viewing positive, negative or neutral images.
Every minute during the tests they rated mood (valence and arousal) and dyspnea (intensity and bothersomness)
Positive mood improved dyspnea
see slides for more detail
basically what was said
Deep breathing and stress
Many Eastern traditions consider breath practices as fundamental to physical, emotional, and spiritual health.
Tai Chi, Yoga, Qigong, meditative breathing.
Different types: Slow breathing, laryngeal closure, breath holding.
Relaxing will increase
parasympathetic/vagal nerve activity, reduces cortisol secretion.
Busch et al. Pain Med 2012
Compared the effect of relaxing versus attentive deep slow breathing on pain threshold, autonomic activity and mood.
Pain threshold increased and sympathetic activity decreased with relaxed deep breathing only.
Deep breathing effects mood, relaxation changes pain threshold
however no significnt difference in reduction of negative emotinos
Summary
The main function of breathing is to replenish O2 and wash out CO2.
Breathing is controlled in the brainstem but has strong links from many higher brain areas.
Due to links between the breathing and emotion centres, breathing has large effects on our emotions/anxiety and stress.
The links between breathing and emotions is bi-directional as evidenced in panic disorder.
