Natalie - Control of Breathing Flashcards
What are the two aspects of respiratory control
Involuntary
Voluntary
Which control is used most of the time
Involuntary control used most often
Why is involuntary control used most open
Its most efficient way to breath
In general what happens when we exert conscious control
Breathing changes
What three things does voluntary control of respiratory rate depend on?
Conscious and unconscious thought
Emotional state
Anticipation
How does conscious and unconscious thought affect respiratory rate?
(2)
e.g. rage or fear
Affect respiratory rate by stimulating centres in the hypothalamus
How can emotional state affect respiratory rate
Depression can slow down RR
How can anticipation affect RR?
If anticipating strenuous exercise
This can cause automatic increase in RR, along with increased cardiac output by sympathetic stimulation
How much control do you have over voluntary breathing
Breathing cannot be consciously suppressed
Can only hold your breath until you lose consciousness then brain takes over
What are the central controllers of the brain
Pons
Medulla
Explain the pathway of control
(3)
Information from various sensors is fed to the central controller
The output of which goes to the respiratory muscles
By changing ventilation, the respiratory muscles reduce negative feedback of the sensors
What are the five receptors of the lung?
Chemoreceptors
Baroreceptors
Stretch receptors
Sensations
Physical or chemical stimuli
What are chemoreceptors
Receptors sensitive to the PCO2, pH or PO2 of the blood or cerebro-spinal fluid
What are baroreceptors
Receptors that detect changes in blood pressure in aortic or carotid sinuses
What are stretch receptors
Receptors that respond to changes in the volume of the lungs and prevent overstretch
How do sensations act as sensors
Sensations of pain, changes in body temperature or abnormal gut sensations
How do physical or chemical stimuli act as sensors
Physical or chemical stimuli in the nasal cavity, larynx or bronchial tree
What does the medulla oblongata do?
Sets pace of breathing
What centres are found in the medulla oblongata?
Respiratory rhythmicity centers
What does the pons do?
Controls breathing pattern (inhalation and exhalation)
What centres are found in the pons?
Apneustic and pneumotaxic centers
What happens in the apneustic centers
(4)
Breathing where long inspirations are interrupted by occasional expirations = snoring sound
Not normally used
Should be switched off
We are not sure why these exist
What happens in the pneumotaxic centre?
Breathing pattern shows a normal balance between inspiration and expiration
What are the effectors of respiration
Respiratory muscles
The inspiratory centres of the brain are influenced by input from where?
The nerves and receptors that monitor the composition of the CSF
What does stimulation of the chemoreceptors lead to?
(2)
Increase in depth
Increase in rate of breathing
How does oxygen chemoreceptors work?
Oxygen:
- monitored by carotid and aortic bodies
- Arterial PO2 must be < 60 mmHg to activate chemoreceptors
- Haemoglobin saturation still 90% at 60mmHg of O2
- Normally it is 100 mmHg and 97% saturated
Why does oxygen concentrations not control breathing?
Because it takes large drop in oxygen levels to cause a dramatic change in breathing
Why is carbon dioxide the main regulator?
CO2 diffuses 20x faster than oxygen
What happens if input from pons is disrupted?
Breathing becomes irregular
What are found in apneustic and pneumotaxic centres?
Paired nuclei that adjust the output of the respiratory rhythmicity centres
Why are pneumotaxic centres most important
Their activities regulate the respiratory rate and depth of breathing in response to input from other centres in the brain
Where is concentrations of CO2 monitored
Monitored by receptors in the medulla oblongata = respiratory rhythmicity centres
What can the centres of the medulla oblongata be divided into?
Dorsal respiratory group (DRG)
Ventral respiratory group (VRG)
When does DRG function
Functions in every respiratory cycle whether quiet or forced breathing
When does VRG function
VRG only functions during forced breathing
What happens in quiet breathing
(6)
Inspiration occurs
Dorsal respiratory group inhibited
Inspiratory muscles relax
Passive expiration occurs
Dorsal respiratory group active
Inspiratory muscles contract
What happens in forced breathing?
(9)
Inspiration occurs
- Dorsal respiratory group and inspiratory center of VRG inhibited.
-Expiratory center of VRG active.
-Inspiratory muscles relax
-Expiratory muscles contract
Active expiration occurs
-Expiratory center of VRG inhibited
-DRG and inspiratory center of VRG active
Inspiratory muscles contract
Expiratory muscles relax
How do lungs help regulate pH
Through carbonic acid-bicarbonate buffer system
How do kidneys help regulate pH
Through renal compensation
How do the lungs regulate pH?
Changing respiratory rates changes partial pressure of CO2
When do respiratory acid base disorders result
Result when abnormal respiratory function causes rise or fall in CO2 in ECF
- acidosis
- alkalosis
What are metabolic acid-base disorders
Generation of organic or fixed acids
Anything affecting concentration of bicarbonate ions in ECF
What is hypercapnia
High carbon dioxide
What does hypercapnia cause?
Respiratory acidosis
What does hypocapnia do?
Respiratory alkalosis
When does respiratory acidosis occur?
When the lungs cannot remove all of the carbon dioxide produced by the body
Body fluids become excessively acidic
What disease cause acidosis
A consequence of any lung disease that prevents removal of carbon dioxide
What are the symptoms of respiratory acidosis?
(4)
Shortness of breath
Easy fatigue
Chronic cough
Wheezing
What causes respiratory alkalosis
Any lung disease that leads to shortness of breath may result in respiratory alkalosis
What is respiratory alkalosis
The pH is high and carbon dioxide levels are low
What are the symptoms of respiratory alkalosis
Light-headedness
Dizziness
Numbness of the hands and feet
What are some treatments for alkalosis
Breathing into a paper bag (re-breathing of carbon dioxide)
