Introduction to the circulatory system Flashcards
what is the circulatory system
a system made up of the cardiovascular system and the lymphatic system
what is the cardiovascular system
made up of the arterial system, the heart, and the venous system (function = distribute gases and other molecules for nutrition, growth and repair)
Pulmonary circulation
right side of heart → lungs → left side of heart
Systemic circulation
left side of heart → capillary beds of organs and tissues → right side of heart
Endocardium(internal):
continuous with endothelium of blood vessels connecting with the heart
Epicardium(external):
visceral serous pericardium
Myocardium(middle):
cardiac muscle layer
conduction system of the heart 1
Electrical impulse starts at SA node - atria contract
conduction system of the heart 2
Impulse travels to AV node at AV septum
conduction system of the heart 3
Impulse travels down left and right bundles in the IV septum
conduction system of the heart 4
Impulse spreads out to myocardium through conducting fibers - ventricles contract
The arterial system
Each artery (and its branches) carries oxygenated blood to a territory
Tunica intima(internal):
endothelium
Tunica media(middle):
smooth muscles and elastic fibres
Tunica adventitia(external):
connective tissue
VASODILATION
Relaxation of the smooth muscle and widening of the lumen to INCREASE blood flow to the organ/tissue supplied
VASOCONSTRICTION
Contraction of smooth muscle to REDUCE blood flow to the organ/tissue supplied
Sympathetic tone:
background, low level contraction of smooth muscle in arterioles
- Due to tonic production of action potentials to arterioles by sympathetic nerves
anastomoses:
where arteries connect to each other without an intervening capillary network
what else do anastomoses do?
- Provides alternative routes for blood flow to supply cells distal to an arterial occlusion
- Each alternate route given by an anastomosis is called acollateral
End artery:
the only arterial blood supply to a given area of the body
infarction:
irreversible cell death due to hypoxia caused by loss of arterial bloody supply
- Result of untreated occlusion of an end artery
what do the left and right coronary arteries do?
supply blood to the heart muscle
what do branches of the arch of the aorta do?
supply blood to the upper limbs and head