Cardiovascular 2 Flashcards
Flow is inversely..
proportional to resistance
-increase in flow, resistance is less
-vice versa
Flow is directly…
Proportional to the 4th power of the vessel radius
-increase radius = decrease resistance, increase flow
Resistance=1/radius to the 4th power
Flow equation
F= 1/ resistance
What is considered the most important factor regarding changes in resistance?
Vessel radius
Flow is inversely proportional to
Both the length of the vessel and viscosity of the liquid
-tube longer and thicker (more viscous) blood
=reducce flow rate
To have the highest possible flow rate
Have a short, large radius tube with low viscosity blood
To have the lowest possible flow rate
Have a long, small radius tube with very viscous (thick) blood
The volume of blood that passes a given point in the system per unit of time (L/min) or mL/ min) is
Flow
Velocity of blood depends on
The flow rate and the cross sectional area
Velocity of Flow
How fast blood flows past a certain point
V= Flow rate / cross sectional area
With an equal flow rate:
The velocity of blood is more rapid in narrow sections of vessel
Heart
-about size of a fist
-located in the center of thoracic cavity
-apex (bottom), base (top)
-apex angles slightly downward to the left of the body
Pericardium around the heart
A tough membranous sac that encases the heart, sandwiches it
What is Pericardium
-a double walled sac filled with a thin layer of clear pericardial fluid
-lubricates the external surface of the heart as it beats within the sac
-this allows the heart to move without friction
The heart is composed mostly of
Myocardium (cardiac muscle) covered by thin inner and outer layers of epithelium and connective tissue
Atrioventricular valves
Right side: Tricuspid
Left side: Bicuspid
-allow flow from atria into ventricles
-attached to papillary muscle in each ventricle by chordate tendinaea
Right atrium to Right ventricle:
Tricuspid valve (3 flaps)
RST
-right side tricuspid
Left atrium to Left ventricle:
Mitral/ Bicuspid valve (2 flaps)
Anatomy of AV valves
-attached to a papillary muscle in each ventricle by chordate tenineae
-blood trying to flow back into atria catches the flaps, closing them shut
-blasting prevented by muscles so flaps don’t allow blood to flow backwards
-these muscles only supply stability to the valves and are not able to open them
Heart valves
Semilunar valves
-one way valves that exist between the ventricle and the outflow artery
-3 cup like leaflets
-don’t need connective tendons due to the shape of them
-the lunar structure allows them to fit together tightly, not allowing blood to come back
Left Ventricle to the Aorta
Aortic semi lunar valve
Right ventricle to the pulmonary artery
Pulmonary semi-lunar valve
During ventricular contraction, AV valves…
Remain closed to prevent blood flow backward into the atria
The valves open/close due to
Pressure gradient in ventricular contraction
Ex) pressure inn LV higher than aorta, that’s why valve opens
-same with the atrium to the ventricle valves (av)
Valves during ventricular relaxation
Semi lunar valves prevent blood that has entered the arteries from flowing back into the ventricle during relaxation
Atrioventricular Ring
Ring of connective tissue that is dense and connected to each other
-attachment point for muscle
-insertion and origin of cardiac muscle attaches here
-contraction pulls atria down towards the ring, ventricles are pulled up
Cardiac conduction potential originates where
In a group of cells in the SA node
-spreads through a network of autorhythmic cells in the heart
-these are many little cells that form the cardiac conduction of the heart
The AV node and what have slower pacemaker activity that is overridden by the SA node?
AV node and the Purkinje fibers are overrriden by the SA node
Whichever region of the cardiac conduction systems generates an AP most frequent…
Sets the pace of the heart for the rest of them
-this is why it is the SA node, as it is about 60-100/min
Av node fire rate
40-60 /min
Purkinje fibres firing rate
15-40/ min
The more HCN channels present,
The faster the depolarization will be
