CO is proportional to tissue mass/metabolic rate

Long term factors that affect CO

• ventricular geometry
  • thickness
  • radius
• ventricular compliance (see pressure, volume loops)
• electrical coordination of contraction

• preload
• afterload
• contractility
• heart rate

• positive chronotropic effect
  • increases rate of phase four depolarization of SA nodal cells → increase HR
• positive dromotropic effects
  • AV node- speed conduction and decrease AV node delay
• positive inotropic effects
  • myocytes- increase atrial and ventricular contractility

• negative chronotropic effect
  • SA node- decrease rate of depolarization of phase 4 → slower heart rate
• negative dromotropic effect
  • AV node- slows conduction, prolong AV delay
• minor negative inotropic effect
  • some affect on atria
    • decrease calcium entry during AP lead to decrease calcium release from SR → weaken contractility

They are the same. When you feel the pulse, you feel the pressure wave. The pressure wave is different from the actually velocity of blood. Since the arteries have sturdy walls, the presure wave moves faster.

Relation of pulse pressure to flow

• peripheral pressure
• stroke volume
• arterial compliance

• greater systolic pressure
• lesser diastolic pressure
• greater pulse pressure

Incisura disappears and hump disappears.

Compare small arteries blood pressure to aorta pressure

• lesser systolic and diastolic pressure
• lesser pulse pressure

• normal: MAP =2/3DP + 1/3SP
• rapid HR: MAP =1/2DP + 1/2SP

Pulse pressure relation with compliance and how this is important as it relates to elastic arteries

• pulse pressure increase with decreasing compliance
• elastic arteries keep pressure from getting too high, thereby causing loss of compliance

• increase stroke volume
• increase systolic pressure
• decrease diastolic pressure (can't hold pressure long since blood is going backwards)
• substantial increases in pulse pressure

• respiratory pump
• aortic pump
• skeletal muscle pump

• contain valves in the veins of the limbs that direct the flow of blood to the heart, preventing edema
• skeletal muscle compress veins durin skeletal muscle contraction

Both of these events force blood back toward the heart. If muscle relaxes, venous pressure in that segment is low.

• blood pools, leading to venous pressure rising
• after which, capillary absorption is reduced
• this leads to increased interstital fluid volumes and swelling

Prolonged quite standing leads to dependent edema and eventually fainting if venous pooling occurs and persists.

• increase intrathoracic pressure
• increase right atrial pressure
• decrease pressure difference
• decrease venous return

• decrease intrathoracic pressure
• decrease right atrial pressure
• increases pressure difference
• increases venous return

• if you stand, your venous blood will drain toward the feet, away from the heart, decreasing venous return
• leads to pooling of blood to stretchable veins
• typically, you will see higher pressures on lower limbs that push blood up toward heart
  • you still have the same pressure gradient pushing blood from arteries to heart, but the pressure in the arteries and veins, respectively, increase equally due to gravity

• auxillary pumps
• total peripheral resistance
• mean systemic filling pressure
• compliance of veins
• effect of gravity
• vascular permeability

• absolute pressure = gravity + driving pressure created by heart

cause venoconstriction, which will reduce venous compliance, increases venouse return