Control of respiration Flashcards
What is the function of the medulla in respiration?
It is the primary respiratory control centre and sends signals to the muscles that control respiration.
What is the function of the pons in respiration?
Another respiratory control centre located beneath the medulla. It controls the rate/ speed of respiration.
What are the centers in the medulla and pons that regulate breathing?
Pons : pontine respiratory group made up of 2 areas; the pneumotaxic center and the apneustic center.
Medulla: the dorsal respiratory group and the ventral respiratory group.
What does the pneumotaxic area do and where is it located?
Located in the upper pons
It sends signals to inhibit inspiration to allow expiration to occur
What does the apneustic centre do and where is it located?
Located in the lower pons
It sends signals to inhibit expiration by activating inspiratory neurones.
It increases tidal volume.
What can the pneumotaxic area override?
The apneustic area.
What is tidal volume?
The volume of air moved into or out of the lungs during normal, quiet breathing.
Describe the dorsal respiratory group…
Inspiratory centre located in dorsal medulla
It sets the basic rhythm of breathing
Describe the ventral respiratory group…
Expiratory centre located in ventral medulla
Active in both inspiration and expiration
Provides high respiratory drive when breathing needs to be increased. (exercise)
Which centre sends signals to diaphragm to contract?
Dorsal respiratory group
Where are central chemoreceptors located?
Medulla oblangata.
What stimulates central chemoreceptors?
Stimulated by [H+] concentration and gas partial pressures in arterial blood
Brainstem [primary influence is PaCO2]
Where are peripheral chemoreceptors located?
Carotid [(IX) cranial nerve afferents]
and aortic bodies [Vagal (X) nerve afferents].
What stimulates peripheral chemoreceptors?
A decrease in PaCO2.
What are peripheral chemoreceptors function?
Responsible for [all] ventilatory response to hypoxia (reduced PaO2)
When exposed to hypoxia, type I cells release stored neurotransmitters that stimulate the cuplike endings of the carotid sinus nerve
Describe mechanoreceptors…
Located in the airway, trachea, lung, and pulmonary vessels.
They provide sensory information to the respiratory center in the brain with regards to lung volume, airway stretch, and vascular congestion.
What are the 3 types of lung receptors (mechanoreceptors)?
Stretch
J receptors
Irritant
Where are SASR (slow adapting stretch receptors) located?
Found in smooth muscle around airways.
What activates SASR?
Lung distension
How do SASR respond to activation?
They inhibit inspiration and so promote expiration.
Where are RASR (rapidly adapting stretch receptors) located?
Between airway epithelial cells.
What activates RASR?
Lung distension and irritants.
How do RASR respond to activation?
Bronchoconstriction - narrowing of the airways
What activates C fibres J receptors?
Increased interstitial fluid volume.
How do C fibres J receptors respond to activation?
They cause rapid, shallowing breathing. Bronchoconstriction and cardiovascular depression.
Is respiratory compensation fast or slow?
FAST!
Why does respiration stop when swallowing?
protecting against the risk of aspiration of food or liquid
Briefly describe the controller-effector-sensor loop.
The sensor detects a change (hypoxia), sends signals along the afferent pathway to the controller. The controller then sends signals along the efferent pathway to the effector. The effector responds.
