Pulmonary circulation Flashcards
Where does oxygen-poor blood leave the heart?
It leaves through the right ventricle
What are the two arteries that supply blood to the lung?
Pulmonary arteries and Bronchial arteries
What are pulmonary alveolar vessels?
Thin walled capillaries that are subject to pressure changes
What are pulmonary extra-alveolar vessels?
Pulmonary arteries and veins that accompany the bronchi in a connective tissue ‘sheath’
What is the bronchovascular bundle?
The connective tissue sheath in the lungs
What determines the behaviour of the extra alveolar vessels?
Determined by pressure changes within the connective tissue space of the bronchovascular bundle
What is the peribronchial plexus?
A network of blood vessels around the bronchi
How much of the total output from the left ventricle goes towards bronchial circulation?
Around 2%
What is the azygous vein?
The azygous vein carries blood from the back of your chest and abdomen to your heart
What is the vasa vasorum?
small blood vessels that supply the walls of larger arteries
What is the consequence of the bronchial vessels anastomose with the pulmonary vessels?
It means that the lungs will not die if one of the circulations is obstructed
What is cardiac output?
The volume of blood that is pumped out the heart per minute (Heart rate X Stroke Volume)
How do pulmonary vessels reduce their resistance when more blood is pumped through the lungs?
Using their smooth muscle they increase their diameter
What is capillary recruitment?
Vessels that were previously closed open up which decreases the overall pressure
How do Horses increase their blood flow?
The right hand side of the heart pumps out around 120ml of blood, so the capillary bed in the lungs receives around 100 (it is specially adapted for this)
What is the species adaptation for smooth muscle in the capillaries
Cows have a large volume of smooth muscle in comparison to dogs/ humans (horses have an intermediate amount) meaning they have a larger response to hypoxia
What is the response to hypoxia in pulmonary circulation?
Vasoconstriction, this means that a lower volume of blood is reaching the lungs
What are the two branches/ Splitting of bronchial circulation?
One branch goes down to the pulmonary level to anastomose with pulmonary circulation and the other part supplies the upper airways before feeding into the azygous vein
What two arteries supply blood to the lungs?
Pulmonary arteries and bronchial arteries
What is the blood flow of the pulmonary arteries?
they carry deoxygenated blood from the RHS of the heart
What is the blood flow of the bronchial arteries?
carries oxygenated blood around the lungs
Where does the bronchial blood flow inevitably drain into?
Thea zygous vein
What do blood vessels do when the blood flow through them increases?
They dilate/ decrease their resistance
What is the main purpose of distension and recruitment?
To ensure that the pulmonary circulation stays at a lower pressure than systemic circulation
Why do horses need larger changes in pulmonary pressure?
allows for faster ventricular filling
How is EIPH caused in horses?
High pressures cause the capillary beds to burst
What veins become distended when pulmonary vessels constrict due to hypoxia?
there is a backflow of blood so jugular veins become distended
What is pulmonary vascular resistance?
PVR is the relationship between the pressure difference between the pulomary arteries and left atria and the cardiac output
