Lec 18-19 Flashcards
What are the 3 respiratory centre areas? (Neural Control)
- Rhythmicity Area
- Apneustic Area
- Pneumotaxic Area
Where is the Rhythmicity Area located?
The medulla oblongata of the brain stem
What do the inspiratory cells of the rhymicity area stimulate? (what nerves)
Phrenic and intercostal nerves
What do the expiratory cells of the Rhymicity Area stimulate? (what nerves)
Intercostal and lower spinal nerves
Where is the Apneustic Area located?
In the lower and mid pons of brain stem
What is the Apneustic Area responsible for?
The stimulation of the inspiratory cells of the rhythmicity area and thereby promotes inspiration
Where is the Pneumotaxic Area located?
In the upper region of the pons of brain stem
What effects does the Pneumotaxic Area have?
- An inhibitory effect on the apneustic area -> indirectly inhibits inspiration
- During exercise: it stimulates the expiratory cells of the rhythmicity area and promotes expiration
What are the 2 types of proprioceptors?
- Joint Proprioceptors
2. Stretch receptors in lungs
How are joint proprioceptors stimulated?
By the movement of the limbs
What effects do joint proprioceptors have?
Cause excitation of the respiratory centre of the brain
=> increase in the rate and depth of breathing
How are stretch receptors stimulated?
- Mechanoreceptors
- Sensitive to stretch/ tension located in the walls of bronchi and bronchioles
What effects do stretch receptors have?
Transmit impulses to the apneustic centre via the vagus nerve
=> inhibition of inspiration known as the Hering Breur Inflation Reflex
Voluntary controls of ventilation?
- Occurs in the cerebral cortex
- Limited control - over-ridden by chemicals
- Can increase or decrease both rate and tidal volume
- Useful for talking, singing, laughing, exercise
What are the 2 types of chemoreceptors in the body to sense arterial levels of oxygen, carbon dioxide and pH?
Central and peripheral chemoreceptors
Where are central chemoreceptors located?
In the medulla oblongata of the brain stem
How are the central chemoreceptors activated?
By the changes in the chemical composition of the cerebrospinal fluid
What happens when there is a rise in acidity sensed by the central chemoreceptors?
- Directly stimulate receptors to send signals to the rhythmicity centre in the medulla oblongata
- It stimulates the phrenic nerve (diaphragm) and external intercoastal nerves (intercostal muscles)
- Result: Ventilation increases by up to 100%
=> reduces CO2 levels and this mechanism is switched off
Where are the peripheral chemoreceptors located?
- Various places in the body
- Aortic bodies in the aortic arch
- Carotid bodies at the junction of the internal and external carotid arteries deep in the neck
How do the peripheral chemoreceptors act?
They are indirect
- aortic bodies act via the vagus nerve
- carotid bodies act via the glosspharyngeal nerve
=> signal the respiratory centre (medulla oblongata), thus stimulates phrenic and external intercoastal nerves)
- Result: increase resp rate and tidal volume by up to 50% -> more O2 exchanged
=> mechanism switched off
How are the peripheral chemoreceptors activated?
Changes in concentrations of CO2 (**), O2, and H+ in arterial blood
