Cardio Flashcards
Cardiovascular System Functions:
- transport of material: gases, nutrients, waste
- communication
- defense against pathogens
- temperature
- hemostasis
Heart is a _____
Pump
- atria receives blood in ventricles
- septum divides left and right halves
Ventricles =
Ventricles = Pump (actual force)
Blood Vessels
- veins, arteries, and capillaries
- pulmonary and systemic circulation
- portal system joins 2 capillary beds in series
Blood is made up of
- cells & plasma
Pressure’s effect on CVS
Pressure = driving force
- pressure = flow (achieved through muscular contraction)
Pressure Change
- created by contracting muscles, transferred to blood
- ventricles create the driving pressure
Dilated BV on P
BV dilate, BP decreases
Constricted BV effect on P
- BV constricted = BP increase
Pressure Gradient Aorta -> Venae Cavae
- pressure gradient is always going down
*** Pressure ONLY increases when hits “pump” aka the ventricles - because the pressure gradient is always decreasing a higher pressure gradient is created which aids in increasing pushability
Flow Equation
Flow {proportional} change in P
- flow through a tube is directly proportional to the pressure gradient
- the higher the pressure gradient, the greater the fluid flow
Flow Resistance Equiation
Flow {} 1/R
- flow in a tube is inversely proportional to resistance
- if resistance increases, flow decreases
- if resistance decreases, flow increases
Poiseuille’s Law
Relationship between resistance and
- length
- viscosity
- tube radius
- resistance is proportional to length (L) of the tube (blood vessel)
- Resistance is proportional to viscosity, or thickness of the blood
———-resistance increases as viscosity increases - Resistance is inversely proportional to tube radius to the fourth power
———resistance decreases as radius increases
The longer the tub the ____ the resistance, the ____ flow you have through it
The longer the tube, the greater the resistance, the less flow you have through it
Most important consideration in resistance
Radius because raised to the 4 power
Greatest resistance to blood flow occurs where and why
Capillaries; because most narrow
Decreased radius = ____ resistance
Increased resistance
Vessel size alters viscosity
- RBC suffer less viscous drag than plasma & move faster than plasma
- hematocrit falls as the vessel size decreases
- vessel radius alters flow characteristics of blood
Vessels are____
Elastic
- allows for absorbable of cardiac output
- lack of elasticity leads to increased work
Under control conditions blood flow out of heart (Qh) is _____ to capillary blood flow (Qr)
Equal
Qr
Capillary blood flow
- determined by the ratio of Pa and R
As CO is increased instantaneously, Qr?
As CO is increased over time, Pa?
- instantaneous increase in CO does not alter Qr
- As Co is increased over time Pa increases
FINALLY Qr=Qh
(Closed system so will balance out to equal by changing P and flow)
Increased Qh (blood flow out of heart) but same arterial pressure and capitals flow =
Increased blood stored in heart
Instantaneous increase in R ____ Qr?
reduces
The heart is composed mostly of
Myocardium
2 sets of heart valves
Ensure one-way flow
- Atrioventricular valves
- Semilunar Valves
AV Valves
- between atria and ventricles
- tricuspid valve on right side
- bicuspid valve (or mitral valve) on left side
Semilunar Valves
- curved to allow flow direction
- between ventricles and arteries
- aortic valve
- pulmonary valve
2 Vena Cava
- deliver blood to right atrium
- superior’ inferior
- NO VALVE, just hole— flows right into right atrium
Papillary Muscles
Independently contract and pull valve open/closed
AV Valve
Valve shape: when ventricle contracts it will push valve shut & force blood to pulmonary artery
- lower pressure = valve shut
During ventricular contraction, the ___ valves remain closed to prevent blood flow backward into the atria
AV Valves
The ___ valves prevent blood that has entered the arteries from flowing back into the ventricles during ventricular relaxation
Semilunar valves
Autorhythmic cells
Pacemakers
- generate basic heart rate
- signal for contraction
- smaller and fewer contractile fibers compared to contractile cells
