Week 8- Control of Lung Function Flashcards
What are the 4 centres found in the medulla oblongata?
Dorsal respiratory group
Ventral respiratory group
Apneustic center
Pneumotaxic centre
What are the inspiratory and expiratory groups? What acronym can be used to remember them?
DIVE: dorsal inspiratory, ventral expiratory
What is the role of the dorsal respiratory group?
Inspiratory centre, controls inspiration and sets the rate
What is the role of the ventral respiratory group?
Expiratory centre, inactive during quiet breathing
What is the role of the pneumotaxic centre?
Its the inspiratory off switch, regulates depth and frequency
What does the pneumotaxic centre inhibit/stimulate?
Inhibits the dorsal respiratory group
What does the apneustic centre inhibit/stimulate?
Stimulates the dorsal respiratory group
What does the dorsal respiratory group inhibit/stimulate?
Inhibits the ventral respiratory group
What does the ventral respiratory group inhibit/stimulate?
Inhibits the dorsal respiratory group and the apneustic centre
When are the apneustic and pneumotaxic centres active during an action potential when theres quiet breathing?
Apneustic: at the bottom of the sloping line (start of AP)
Pneumotaxic: at the top of the sloping line (end of AP)
What respiratory muscles do motor nerves innervate?
Intercostal muscles
What respiratory muscles do sympathetic nerves innervate?
The spine
What respiratory muscles do parasympathetic nerves innervate?
Of the pulmonary plexus
What common molecule can cross the blood brain barrier and why?
Co2 as its lipid soluble
What does Co2 enter after crossing the blood brain barrier?
CSF
What happens to Co2 after it has crossed the blood brain barrier and is in the CSF?
It combine with water to form carbonic acid, which then dissociates, the H+ formed then enters the medulla and goes to the dorsal respiratory nucleus
Why is it helpful that Co2 can cross the blood brain barrier?
It is an indicator of metabolism, so the vol of H+ that reaches the medulla/dorsal respiratory nuclei can indicate to the brain how much metabolism is occurring in the body
What 3 receptors in the pulmonary system affect ventilation?
Irritant receptors
Stretch receptors
J receptors
Where are irritant receptors found?
In and underneath the epithelial lining of the trachea
Where are stretch receptors found?
In the bronchi, deeper in the airway
Where are J receptors found?
At the alveoli
What is the function of irritant receptors?
To cause coughs
What is the function of stretch receptors? How do they do this
To increase expiration and reduce inspiration during excessive inflammation of the airways. They do this by inhibiting DR group and apneustic centre and stimulating VR group and pneumotaxic centre in the medulla oblongata
What is the function of J receptors?
To increase breathing frequency in the case of pulmonary capillary engorgement and oedema
What ions enter RBCs to maintain resting potential?
Chloride
What transporter do chloride ions enter RBCs through?
AE1 transporter
How does blood react to changes in pH?
It has enormous buffering capacity and can react almost immediately to pH imbalances
What is the equation used for calculating conc of H+ from pH?
10 to the negative power of the pH
What is the equation used for calculating pH from conc of H+ ?
-log base 10 [H+]
Define alkalaemia
A higher than normal blood pH
Define acidaemia
A lower than normal blood pH
Define alkalosis
Circumstances that will decrease pH and reduce [H+]
Define acidosis
Circumstances that will reduce pH and increase [H+]
What stimulates a slow response to an increase/decrease in pH?
Changes in HCO3- and H+ retention/secretion in the kidneys
How is blood pH altered rapidly?
Changes in ventilation stimulate rapid compensatory responses changing Co2 elimination
Where are peripheral chemoreceptors located
Near baroreceptors
What do efferents from the primary motor cortex to skeletal muscle partially innervate?
The medulla
What do proprioreceptive afferent and golgi tendon organs innervate on the way to the brain?
The medulla
How does skin effect breathing?
Cold temperature (eg immersion in water) trigger hyperventilation
Is acidosis or alkalosis induced after hypoventilation?
Acidosis
Is acidosis or alkalosis induced after hyperventilation?
Alkalosis
Why is acidosis induced after hypoventilation?
Less fresh air reaches the lungs, this increases co2 conc in alveoli, reduces conc gradient, increases co2 conc in post alveolar blood, co2 combines with water to form carbonic acid, carbonic acid dissociates more to H+ ions, increased conc of H+ reduces pH and induces respiratory acidosis
Why is alkalosis induced after hyperventilation?
More fresh air reaches lungs, co2 in alveoli decreases, conc gradient increases, less co2 in post alveolar blood, less co2 combines with water, less carbonic acid synthesis and dissociation, cons of H+ falls
Describe how partial compensation of respiratory acidosis is achieved
Acute phase: excess co2 enters RBCs and combines with water to form bicarbonate, this is excreted via AE1 transporter, increased bicarbonate shifts the carbonic acid equilibrium left reducing the conc of H+ and increasing pH
Chronic phase: increased bicarbonate reabsorption in the kidney
How many stages to partial compensation are there after respiratory acidosis? What are they called?
2- acute first and then chronic
How many stages to partial compensation are there after respiratory alkalosis? What are they called?
1- no acute is present, only chronic
Describe partial compensation after respiratory alkalosis
Chronic phase: increased reabsorption of bicarbonate in the nephrons, increased secretion of bicarbonate from renal collecting ducts
Describe what happens to pH during pre, under compensation, partial compensation and full compensation of respiratory acidosis
Pre: normal range
Under comp: pH is low
Partial comp: pH gradually increases
Full comp: pH is normal rage again
Describe what happens to p [co2] during pre, under compensation, partial compensation and full compensation of respiratory acidosis
Pre: normal range
Under comp: co2 conc is high
Partial comp: co2 remains high
Full comp: co2 conc remains high
Describe what happens to base excess during pre, under compensation, partial compensation and full compensation of respiratory acidosis
Pre: normal range
Under comp: normal range
Partial comp: high
Full comp: high
Describe what happens to pH during pre, under compensation, partial compensation and full compensation of respiratory alkalosis
Pre: normal range
Under comp: pH is high
Partial comp: pH gradually decreases
Full comp: pH is normal rage again
Describe what happens to p [co2] during pre, under compensation, partial compensation and full compensation of respiratory alkalosis
Pre: normal range
Under comp: co2 conc is low
Partial comp: co2 remains low
Full comp: co2 conc remains low
Describe what happens to base excess during pre, under compensation, partial compensation and full compensation of respiratory alkalosis
Pre: normal range
Under comp: normal range
Partial comp: low
Full comp: low
