Resp Conditions Flashcards
Conducting airways
Trachea (Rings of cartilage)
Bronchi - trachea to lungs
- as bronchi approach lungs they become narrower and break off into branches known as bronchioles
Aveolar ducts
- connection to aveoli
Where does gas exchange occcur in the lungs
Aveoli
Aveloar acapillerly membrane
Less than 5 cm thick
Site of gas exchage
If filled with fluid, gas exchange is impaired
Functional components of the respirotary system
Neurochemical control
Mechanics of breathing
Gas transpoprt
Control of Pulmonary Circulation
Respiratory Defense mechanisms
Peripheral ChemorecepotORS
Located in clusters composing the aortic body and carotid bodies, in similar locations to baroreceptors
These recepotrs sense changes in O2, and CO2 levels as the rate of perfusion into and out of their cells changes from the capilleries since they get high levels of blood flow, the perfusion rate of O2 in and CO2 out is an accurate measure of the level in the body. And since CO2 and O2 together compose Bicarbonate and Hydrogen - the major players in acid base balance, chemorecepotrs also measure this.
If there is an upset in levels, the chemoreceptors releases neurotranspmitters to a cranial nerve nearby to stimulate compensatory mechanisms
Which nerves are associated with chemoreceptors
Vagus nerve and glossopharyngeal (10 and 9)
Where do the cranial nerves associated with chemoreceptors travel to?
to themedulla oblongataand theponsin the brainstem. Several responses are then coordinated which aim to restore pO2.
What response would the brainstem stimulate if there was low pO2
Therespiratory rateandtidal volumeare increased to allow more oxygen to enter the lungs and subsequently diffuse into the blood
Blood flowis directed towards the kidneys and the brain (as these organs are the most sensitive to hypoxia)
Cardiac Outputis increased to maintain blood flow, and therefore oxygen supply to the body’s tissues
Central chemorecptors
Central chemoreceptors are located in the medulla oblongata of the brainstem. They detect changes in the arterial partial pressure of carbon dioxide (pCO2). When changes are detected, the receptors send impulses to the respiratory centers in the brainstem that initiate changes in ventilation to restore normal pCO2.
Response to high levels of pCO2 in blood
Detection of an increase in pCO2 leads to an increase in ventilation. More CO2 is exhaled, the pCO2 decreases and returns to normal.
Response to low levels of CO2 in blood
Detection of a decrease in pCO2 leads to a decrease in ventilation. Less CO2 is retained in the lungs, the pCO2 increases and returns to normal.
What is different about the mechanism of pCO2 in central chemoreceptors
The mechanism behind how central chemoreceptors detect changes in arterial pCO2 is more complex, and is related to changes in the pH of the Cerebral Spinal Fluid (CSF).
What do central chemoreceptors respond to
High CO2 levels
Low pH
NOT O2 levels
Muscels of inspiration
Diaphragm
External interscostal muscels
Accessory muscle
- (sternalcremastoid)
- Scalene
What is compliance in relation to lung elasticity
The ability of the lung to stretch and expand
Airway ressistiance
Normally low
Edema, obstruction, and bronchospasm can increase airway ressitsnce
- Causing breathing to becom more difficult
Aveolar surface tension
Surfactant a lipoprotein reduces the surface reducing the amount of pressure needed for the alveoli to inflate and decreases their tendency to collapse.
Work of breathing
Detereined by musclular effort required for ventilation
Normally low but increased by certain dx
Gas transport of O2
Ventilation of lungs
Diffusion of O2 from alveoli into capillary blood
Perfusion of systemic capillaries with oxygenated blood
Diffusion of O2 from systemic capillaries into cells
Gas transport of CO2 (Removal)
Diffusion of CO2 from cells into systemic capillaries
Perfusion of pulmonary capillary bed by venous blood
Diffusion of CO2 into alveoli
Removal of CO2 from lungs by ventilation
How does oxygenated blood reach the body?
Oxygenated blood travels from the lungs through the pulmonary veins and into the left side of the heart, which pumps the blood to the rest of the body.
How does O2 deficient blood (CO2 rich) reach the lungs?
Oxygen-deficient, carbon dioxide-rich blood returns to the right side of the heart through two large veins, the superior vena cava and the inferior vena cava. Then the blood is pumped through the pulmonary artery to the lungs, where it picks up oxygen and releases carbon dioxide.
How is pulmonary circulation controlled?
Inside diameter (Caliber) of pulmonary artery lumina decreases as smooth muscle in arterial walls contracts
Contraction increases pulmonary artery pressure
Most inportatn cause of pulmonary arterey constriction
Low PaO2
Low O2 in the blood - alveolar hypoxia - hypoxic vasoconstriction
