Control of Lung Function Flashcards
Medulla oblongata:
What are the functions of the dorsal respiratory group and ventral respiratory group?
Dorsal respiratory group:
inspiratory centre
Main controller of inspiration
Sets the rate
Ventral respiratory group:
Expiratory centre
Inactive during quiet breathing
Inhibit apneustic centre
Medulla oblongata:
What are the functions of the apneustic centre and pneumotaxic centre?
Apneustic centre:
Stimulates activity in DRG
inhibited by pulmonary afferents
Pneumotaxic centre:
The inspiratory off switch
Regulates depth and frequency (of inspiration)
What are the 4 groups/centres in the medulla oblongata
DIVE - Dorsal, Inspire, Ventral, Expire
Dorsal respiratory group
Ventral respiratory group
Apneustic centre
Pneumotaxic centre
Innervation of respiratory muscles:
Parasympathetic
Sympathetic
Motor
Parasympathetic innervation: Jugular ganglion Nodose ganglion Superior cervical ganglion Vagus nerve Pulmonary plexus
Sympathetic innervation:
Thoracolumbar nerves ; C1-C8, T1-T12
Motor innervation:
Phrenic nerve ( made up of C3,4,5)
Intercostal nerves
Internal intercostal muscles - expiration
External intercostal muscles - inspiration
Chemosensitivity in the medulla:
The normal circulation - continuous capillaries
H2O filled gap junctions
The blood brain barrier (BBB) - continuous capillaries, tight junction
Charged/large molecules can’t pass BBB
CO2 is highly lipid soluble
Once CO2 passes BBB, it can react w water to generate H+ and HCO3-
Protons produced interact w afferent fibres in the medulla which take the signal to the dorsal respiration group to determined what type of rate and rhythm should be created
Pulmonary afferents that affect ventilation:
What are irritant receptors?
Where are they found?
What do they lead to?
What are stretch receptors?
What activates pulmonary stretch receptors?
What do they do?
J receptors:
What are they sensitive to?
What do they do?
Irritant receptors:
Detect foreign matter - solid, fluid or gas, have short reflex that results in coughing
Afferents receptors embedded within and beneath airway epithelium
Leads to cough - involves forceful expiration against a closed glottis with sudden glottal opening & high velocity expulsion of air
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
J-receptors:
Sensitive to oedema and pulmonary capillary engorgement
Increases breathing frequency
Acid base homeostasis:
What is an acid?
What leads to lower pH?
What is a base?
What reaction is in eqm? What happens is the quantities of a reactant/product increases?
What is chloride shift?
Acid = any molecule that can donate H+ ion / proton
Greater conc of H+ -> lower pH
Acidity of blood must be tightly regulated, marked changes alter the 3D structure of proteins (enzymes, hormones, protein channels)
Base = anionic (negatively charged ion), accepts protons - reversibly binds
HA
Relationship is in eqm, increasing someone on one side, shifts eqm to opposite side
Chloride shift:
Neg chloride ions enter the RBC to maintain resting membrane potential
Blood has massive pH buffering abilities
What can stimulate a rapid compensatory response to alter pH and how?
What stimulates a slow compensatory response to increase/decrease pH?
What is required to correct an acidosis?
Changes in ventilation can stimulate a rapid compensatory response to change CO2 elimination and hence alter pH
Changes in HCO3- and H+ retention/secretion in the kidneys can stimulate a SLOW compensatory response to increase/decrease pH
Acidosis needs alkalosis to correct it
Alkalosis needs acidosis to correct it
Peripheral chemoreceptors:
Where are they located?
Where are the carotid bodies?
Where are the aortic bodies?
Peripheral chemoreceptors are positioned near the carotid baroreceptors (sensitive to changes in blood pressure)
Carotic bodies are in aortic arch
Aortic bodies are in aortic arch
What regulates emotional change to ventilation?
Higher brain centres / special senses —> emotional response —> respiratory control centre
Breathing during exercise:
Efferents from which motor cortex cross through where to innervate the medulla?
What type of afferents from which structures innervate the medulla on the way to the brain?
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 are the effects of skin afferents on breathing?
Immersion in cold water <10 oC:
Ventilatory
Inspiratory gasp/hyperventilation
Relationship between the centres in the medulla oblongata
Dorsal and ventral groups inactivate each other, bc If you’re inspiring you’re not expiring & vice versa
Apneustic centre stimulates the dorsal centre
Pneumotaxic centre provides inhibition to the dorsal centre
Apneustic centre inhibits the ventral centre
Define the following terms:
Alkalaemia
Acidaemia
Alkalosis
Acidosis
Alkalaemia - higher than normal pH of blood
Acidaemia - lower than normal pH of blood
Alkalosis - describes circumstances that will decrease [H+] and increase pH
Acidosis - describes circumstances that will increase [H+] and decrease pH
