Control of Lung Function Flashcards
What are the 4 main respiratory nuclei in the medulla oblongata?
Dorsal respiratory group
ventral respiratory group
apneustic centre
pneumotaxic centre
What is the dorsal respiratory group?
Inspiratory centre
Main ‘controller’ of inspiration
Set the ‘rate’
What is the ventral respiratory group?
Expiratory centre
Inactive during quiet breathing
Inhibit apneustic centre
What is the apneustic centre?
stimulates activity in the dorsal respiratory group
What is the pneumotaxic group?
The inspiratory off switch
Regulates depth and frequency
How does DIVE mnemonic help?
dorsal inspiration
ventral expiration
What inhibits what and what stimulates what out of the groups?
Apneustic centre stimulates dorsal
ventral respiratory group inhibits dorsal and apneustic
dorsal inhibits ventral
pneumotaxic inhibits dorsal
What are the respiratory pacemakers during quiet breathing and how do they work?
ramp potential pattern
What is the innervation of respiratory muscles?
Parasympathetic
- vagus nerve
- to pulmonary plexus and meets up with sympathetic nerve
- goes to medulla
- jugular and nodose ganglion
Sympathetic
- sympathetic chain
- comes out of spinal cord
Motor
- diaphragm with phrenic nerve
- intercostal muscles with intercostal nerves
What type of capillaries does normal circulation and the BBB have?
normal= continuous capillaries (H2O-filled gap junction)
BBB= continuous capillaries (w/ Tight junction)
What can and cannot pass the BBB?
charged/ large molecules cannot pass the BBB
CO2 is highly lipid soluble so it can
What is the relationship between the BBB, CSF, medulla and the molecules H+, CO2, HCO3-?
H+ and HCO3- cannot pass the BBB
CO2 can so it enters the CSF and reacts with water
This forms H+ ions and HCO3-
The H+ ions enter the medulla
These protons directly stimulate afferent nerves
What are the Afferents that affect ventilation?
Irritant receptors
Stretch receptors
J-receptors
What are irritant receptors?
Afferent receptors embedded within and beneath airway epithelium
Leads to cough: which involves forceful expiration against a closed glottis with sudden glottal opening & high velocity expulsion of air
What are stretch receptors?
Excessive inflation of lungs activates pulmonary stretch receptors
Afferent signals to respiratory centres inhibit DRG and apneustic centre and stimulate pneumotaxic VRG
Inspiration inhibited & expiration stimulated
What are j-receptors?
Sensitive to oedema and pulmonary capillary engorgement
Increases breathing frequency
Where is the location of stretch, irritant and j-receptors?
What is volitional apnnoea?
Voluntarily not breathing for a long period of time
What happens to ventilation, PaO2 and PaCO2 during volitional apnea?
What is inspiration stimulated by?
Central H+ concentration
Juxtacapillary oedema/ pulmonary engorgement
Motor control
Limbic system
Peripheral O2 concentration
peripheral proprioceptors
Skin thermoreceptors
What is expiration stimulated by?
airway stretch receptors, limbic system, motor control
what is coughing stimulated by?
airway irritant receptors
What is an acid?
any molecule with a loosely bound H+ ion that it can donate
What happens if the acidity of the blood is not regulated?
alters the 3D structure of proteins (enzymes, hormones, protein channels)
How would you describe a base?
anionic (negatively charged ion) capable of reversibly binding protons
What is the balanced equilibrium equation with H+ ions?
What is the equilibrium equation for H2CO3?
What is an example of acid base homeostasis?
chloride shift
How was the buffering capacity of blood identified?
by Pitts and Swan
Dog is anaesthetised and baseline bloods drawn pH= 7.44
The dog was then injected with 14 molar acid
- they expected the dog to die with a pH of 2.5
What actually happened is the dog survived and had a pH of 7.14
What is amazing about the blood buffering capacity?
enormous buffering capacity and can react almost immediately to imbalances
What are the log rules for pH?
What is alkalaemia?
Refers to high-than-normal pH of blood
What is acidaemia?
Refers to lower-than-normal pH of blood
What is alkilosis?
Describes circumstances that will decrease [H+] and increase pH
What is acidosis?
Describes circumstances that will increase [H+] and decrease pH
What do changes in ventilation lead to?
Can stimulate RAPID compensatory response to change in CO2 eliminate and therefore alter pH
What can changes in certain ions retention in the kidneys lead to?
Changes in HCO3- and H+ retention/secretion in the kidneys can stimulate a SLOW compensatory response to increase/decrease pH
What do you need during acidosis and what do you need during alkilosis?
An acidosis will need an alkalosis to correct
An alkalosis will need an acidosis to correct
Where are peripheral chemoreceptors?
Positioned near the carotid baroreceptors (sensitive to changes in blood pressure)
What are aortic bodies and where are they found?
in aortic arch
Cells detect blood pH and also oxygen and carbon dioxide tensions
What is the HbO2 saturation (%) like in systemic and pulmonary circulation?
How are emotional responses important for changes in ventilation?
limbic system
What happens to breathing during exercise?
Efferents from primary motor cortex to gross skeletal musculature partly innervate medulla
Proprioceptive afferents from muscle spindles & golgi tendon organs innervate medulla on way to brain
What is the effect of skin afferent on breathing while being immersed in cold water (<10C)?
Inspiratory gasp/ hyperventilation
What is the blood pH tightly regulated at?
7.35-7.45
What does the term -osis refer to?
conditions precipitating a changing pH
How would you describe pH in terms of logs?
pH is inversely and logarithmically proportional to proton concentration
What are the 2 types of pH disturbances?
respiratory or metabolic
What are compensatory responses usually and give examples?
Compensatory responses are usually the opposite of the original aetiology
(e.g. respiratory disturbance has renal response and metabolic disturbances have respiratory response)
Do you understand these diagrams?
basic blood gas disturbances
What are basic blood gas disturbances?
hypo and hyperventilation
diarrhoea
vomiting
