CV II Flashcards
What opposes flow
Fluid encountering friction from walls of tube and cells in blood colliding
What is flow inversely protportional to
Resistance
If resistance increases, blood flow decreases
What is flow
Not speed but volume over time
What 3 parameters determine resistance?
r= radius of tube
l= length of the tube
n= viscosity of the fluid within the tube
What is directly proportional to resistance
Length and viscosity
If one increases resistance increases
What is inversely proportional to resistance
4th power of the vessel radius
Larger radius, decrease resistance
Increased blood flow
What is the most important factor regarding changes in resistance
Vessel radius
Small changes in radius cause large changes in resistance
What is flow inversely proportional to
Length of vessel and viscosity of liquid
What will a shorter length tube have
Less resistance and more flow
What does velocity depend on
Flow rate and cross sectional area
What is flow
Volume of blood that passes a given point in the system per unit time (ml/min or L/min)
Volume/time
What is velocity of flow
Distance a fixed volume of blood travels during a given time period of time
How fast blood flows past a certain point
V= flow rate/x-sec area
With an equal flow rate, the velocity of blood is more rapid where
In narrow sections of vessel
What in one minute how much work does the heart perform
Equivalent work of lifting 5-pound weight up 1 foot
How often does the heart contract in 70 year life span
> 2.2 billion times
Where does the heart lie
Center of thoracic cavity on ventral side sandwiched between lungs
How big is heart
About size of fist
How does heart sit
Apex (bottom) angled slightly downward to left of body, base is at top (widest part)
What is the pericardium
A double walled sac filled with a thin layer of clear pericardial fluid
Lubricated external surface of the heart as it beats
What is heart encased in
Tough membranous sac known as pericardium
What is heart mostly composed of
Myocardium (cardiac muscle)
What is heart covered by
Thin inner and outer layers of epithelium and connective tissue
Parietal pericardium - most outside
Pericardial cavity
Visceral pericardium- inside
Why are there no valves in arteries
Pressure very high and never drops enough for blood to flow backwards
What two sets of valves allow for one-way flow through heart
Atrioventricular valves
Semilunar valves
What are atrioventricular valves and what are two kinds
Allow flow from atria into ventricles
- tricuspid valve
- bicuspid valve
What valve is from RA to RV
Tricuspid valve
Waht valve is from LA to LV
Mitral valve (bicuspid)
What are atrioventricular valves attached to
Papillary muscle (extension of cardiac muscle) in each ventricle by chordae tendineae (tendon)
- don’t open valves, valves open by pressure
What do the papillary muscle do
Supply stability to the valves and are not able to open them
What are semilunar valves
One way valves that exist between ventricle and outflow artery
- have 3 cups like leaflets
What are two semilunar valves
Aortic valve and pulmonary valve
Aortic valve
LV to aorta
Pulmonary valve
RV to pulmonary artery
Do semilunar valves have connective tendons
No due to the shape of them
Lunar structure helps them fit together to prevent prolapse
