Principles Circulatory System Flashcards
What are the 2 main circulations?
Pulmonary and Systemic
Where does the pulmonary circulation go?
From the right side of the heart to the lungs
Where does the systemic circulation go?
From the left side of the heart to all body tissues
What is the average pulse rate?
70bpm
What are the 3 layers of the heart?
Epicardium, myocardium and endocardium
What is the epicardium?
Visceral serous pericardium
What is the myocardium?
The middle muscular layer
What is the endocardium?
It is continuous with endothelium of blood vessels
What does the pulmonary trunk divide into?
Right and left pulmonary arteries
What do cardiac valves ensure?
Unidirectional flow
What layers are most blood vessels comprised of?
- Tunica intima (internal) - endothelium
- Tunica media (middle) – smooth muscles and elastic fibres
- Tunica adventitia (external) – connective tissue
What do ‘common’ and ‘trunk’ indicate?
That the artery will definitely divide again?
What does bifurcate mean?
Splits into 2
Where are arteries usually located?
Deeper than veins
What does vasodilation mean?
Relaxation of the smooth muscle and widening of the lumen to INCREASE blood flow to the organ/tissue supplied
What does vasoconstriction mean?
Contraction of smooth muscle to REDUCE blood flow to the organ/tissue supplied
What is the sympathetic tone?
Background, low level of contraction of smooth muscle in arterioles
What causes the sympathetic tone?
The tonic (continuous) conduction of action potentials to arterioles by sympathetic nerves
Fun fact
Arteriolar smooth muscle contraction can help to reduce blood loss following an injury (the vessel is said to be in “spasm”).
What is an anastomosis?
Where arteries connect with each other without an intervening capillary network.
What is the purpose of an anastomosis?
Provides alternative routes for blood to flow to supply the cells distal to an arterial occlusion (blockage)
What is the Circle of Willis?
The arterial anastomosis of the brain.
What does the Circle of Willis prevent?
a cerebrovascular accident (CVA/Stroke)
What is a collateral?
Each alternative route in any given anastomosis
