Physiology - Respiratory System: Control & Responses to Exercise Flashcards
Where are central chemoreceptors based in?
Respiratory centre.
Where is the respiratory centre located?
Located in the medulla oblongata and pons, in the brainstem.
What is the respiratory centre made up of?
- 3 major respiratory groups of neurones
- 2 in the medulla, 1 in the pons
What is the respiratory centre responsible for?
Responsible for generating and maintaining the rhythm of respiration, and also of adjusting this in homeostatic response to physiological changes.
Homeostasis?
The tendency to resist change in order to maintain a stable, relatively constant internal environment.
Where are central chemoreceptors based?
Based in the respiratory centre.
Central chemoreceptors?
They detect changes in the arterial partial pressure of carbon dioxide. When changes are detected, the receptors send impulses to the respiratory centre to restore normal partial pressure of carbon dioxide.
pCO2?
Partial pressure of carbon dioxide.
The measure of carbon dioxide in the arterial or venous blood.
(central chemoreceptors) As CO2 is produced it passes across…
the blood brain barrier and dissolves in CSF.
CSF?
Cerebrospinal fluid.
(central chemoreceptors) Blood is well buffered due to chemicals such as haemoglobin and plasma proteins, therefore…
little change in pH occurs during exercise.
Buffered?
Moderates the impact of something.
(central chemoreceptors) CSF is not well buffered, therefore…
pH falls when pCO2 increases.
(central chemoreceptors) Fall in pH is sensed and…
stimulates breathing.
The main drive for breathing is…
increased CO2, not lack of oxygen.
Where are the peripheral chemoreceptors based?
- Carotid body
- Aortic bodies
Function of peripheral chemoreceptors?
Detect changes in arterial blood oxygen and initiate reflexes that are important for maintaining homeostasis during hypoxemia.
Hypoxemia?
Low level of oxygen in blood.
What do the pons and medulla oblongata regulate? What can override this through voluntary control?
Inspiration & expiration.
Cerebral cortex.
Where is the cerebral cortex located?
In the brain.
What are the pons and medulla oblongata controlled by? What does it actively cause?
The inspiratory and expiratory centres.
Actively causes the contraction of the diaphragm during exercise and decreases the volume in the thorax.
What is the inspiratory centre controlled by? What has a small input?
The central chemoreceptors.
Peripheral chemoreceptors.
What informs the inspiratory centre that inspiration needs to be affected?
Active muscles.
What drives the diaphragm and expands the external intercostal muscles to change the volume inside your lungs?
The inspiratory centre.
What lets the expiratory centre know that expiration needs to occur?
Lung stretch receptors.
Hering-Breuer reflex?
- Initiated by lung expansion/stretch receptors.
- Causes the relaxation of the intercostal & abdominal muscles.
- Shortens duration of inspiration.
