Flashcards in Integration of cardiovascular mechanisms Deck (48)
Factors which influence MAP?
Systemic vascular resistance
Main site of systemic vascular resistance?
Components of cardiovascular system?
Heart - pump
Arteries - passageway of blood from heart to tissues
Arterioles - major resistance vessels
Capillaries - Site of gas exchange, nutrients and water between blood and tissues
Veins - Contains most of blood volume during rest - passageways of blood from tissues to heart
What must venous return provide?
The heart with sufficient blood to pump
Name for veins?
How is HR mainly regulated?
Autonomic nervous system
How is SV mainly regulated?
CO= HR x SV
How can MAP be estimated?
DBP + 1/3 pulse pressure
How is systemic vascular resistance regulated?
By vascular smooth muscles
What does contraction of vascular smooth muscles cause?
Vasoconstriction and decreases SVR and MAP
What are vascular smooth muscles controlled by?
Intrinsic and extrinsic mechanisms
What is resistance to blood flow directly proportional tp?
Blood viscosity and length of blood vessel
What is resistance to blood flow inversely proportional to?
Radius of blood vessel to the power of 4
Resistance to flow equation?
R proportional to n.l/r^4
L= length of blood vessel
r= radius of blood vessel
R= resistance to flow
What does extrinsic control of vascular smooth muscle involve?
Nerves and hormones
If we constrict muscle in arterioles what happens?
Increases resistance and decreases flow
What are vascular smooth muscles supplies by?
Sympathetic nerve fibers
Vascular smooth muscle neurotransmitter and receptor it works on?
acts on alpha receptors
Vascular smooth muscle partially constructed at rest
Control of vascular smooth muscles via hormones?
Depends on predominant type of receptor
What does adrenaline acting on alpha receptors cause?
What causes vasodilation?
Adrenaline acting on beta 2 receptors
Where are alpha receptors predominantly found?
What receptor is found on cardiac and skeletal muscle arterioles?
Other hormones which extrinsically affect vascular smooth muscle control?
Angiotensin 2- causes vasoconstriction
Antidiuretic hormone- causes vasoconstriction
What do local metabolic changes within an organ influence?
Contraction of arteriolar smooth muscles
What factors causes relaxation of arteriolar smooth muscles?
What do other local chemicals released within an organ influence? and when are they released
Contraction of arterial and arteriolar smooth muscles
Following a tissue injury or inflammation