L19 - Respiratory Control Flashcards
Describe respiratory system anatomy.
nose/mouth –> wind pipe –> trachea –> splits down right/left lungs –> “tree” divides 24 times –> @ end of branches there is alveoli, which are bunches of interconnected balloons —> THIS IS WHERE MAIN EXCHANGE OF GAS OCCURS
How does gas exchange happen?
fresh air, which has 20% oxygen, enters the lungs during inspiration.
LOW oxygen and HIGH co2 blood entering the lungs from the body has the O2 replenished and CO2 removed by diffusion in the alveoli - this happens through the capillaries on the alveoli, which have membranes so thin that oxygen can diffuse through and replenish blood.
HIGH co2/lowo2 air is breathed out during expiraiton.
Describe the two movements in breathing and the muscles it uses.
Inspiration - ACTIVE, diaphragm and intercostal muscle activation -
Expiration - PASSIVE at rest, relies on recoil of lungs/chest wall. ACTIVE during exercise/stress using abdominal muscles - also active at rest for people with respiratory problems.
there is -ve pressure, as long as mouth is open, air will flow in
How are the muscles using in respiration innervated?
- PHRENIC NERVES which innervate the diaphram exits the spinal cord at neck!!
- intercostal nerves innervate intercostal muscles (muslces between ribs)… all at diff spots
- acessory muscles such as abdommen is activated during high work/cough - lumbar spinal cord.
How is breathing controlled?
controlled in the brainstem.
Pons
Pontine respiratory group - all inputs, such as voluntary and involuntary inputs come through here
Retrotrapazoid Nucleus - how the body senses CO2.
if you stop breathing, the drive to breathe increases due high levels of CO2 activating the RTN.
Medulla
- Ventral respiratory group
- Boetzinger
- Pre Boetzinger - breathing pacemaker cells - causes autonomic breathing
O AND CO2 ARE ALSO SENSED IN THE PERIPHERAL CARTIES AND THESE SIGNALS ARE SENT TO RTN - if you lower o2 levels enough, these will stim breathing as well - chemoreceptors.
Brain stem has specialised areas which are all interrelated and work together to control breathing
What are the inputs to the respiratory centres?
Central (non-brainstem areas of brain), primarily to the PRG
- volitional, pain, temp (Fever), emotion
- speech, swallow, cough, sneeze, hiccup
- sleep, exercise, defecation, paturition
- panting, sonar
Peripheral
- Chemosensors come through the RTN
- lung irritant/stretch - reflex - through dorsal respiratory group
Emotions and respiratory control?
Amygdala - to the PRG
- connection such that emotional stimuli results in respiratory rate increase
Amygdala - to the DRG
results in inspired volume increase and rate
Basolateral Amygdala and hypothalamus - also CO2 sensitive and can feed into emotional responses.
lack of 02 = sense of fear
fear and anger –> increase resp rate and sometimes depth
positive affect – slow, and deep when excited, or shallow for calm.
BI DIRECTIONAL RELATIONSHIP
What is panic disorder?
- Frequent, unexpected acute panic attacks.
- panic attacks are episodes of overwhelming anxiety and distress with air hunger, shortness of breath and hyperventilation.
symptoms occur due to over-breathing, leading to a lack of O2
abdomen - nausea cramping
senses - blurred vision, dry mouth, distant sounds
consciousness - dizziness, fainting, confusion
muscles - weakness, spasms
What is the suffocation “false alarm” hypothesis?
Hypothesises that people with panic disorder have a heightened co2 sensitivity.
The cycle
Stress –> hyperventilation –> low CO2 –> tingling extremeties, heart palpitations –> stress and symp activation –> hyperventilation etc.
break the cycle is the best treatment
Why does breathing in a bag helpful?
Brings co2 back into the blood by breathing back in your co2.
since co2 levels will be too low after hyperventilationg.
What are breathe holding spells?
Involuntary breath holding in toddlers during a tantrum or when they’re very upset.
turn blue, can pass out and have a seizure.
the emotional input to the respiratory controller is very strong.
What is dyspnea?
The discomfort associated with being short of breathe/breathless.
How is dyspnea affected by mood?
When subjects were told to briskly walk whilst viewing positive, negative or neutral stimuli, they rated their dyspnea.
- Mood was affected by the stimuli
- arousal was affected by stimuli
- more dyspnea with NEGATIVE MOODS
mood/emotion has impact on breathing : )
Deep breathing and stress?
Taichi, yoga, meditation all have different types of breathing, are eastern traditions that consider rbeathing pratices fundamental to emotiona, physical and spiritual health.
- Relaxing will increase parasymp/vagal nerve activity and reduce cortisol secretion.
- study found that pain threshold increased and sympathetic activity decreased with relaxed deep breathing, but not attentitve deep slow breathing.
