Notes college 1
- The Cardiovascular system and Hemodynamics -
Functions of the cardiovascular system:
1. Primary:
- Distribution/transport of dissolved gasses and other molecules for nutrition,
growth and repair
2. Secondary:
- Fast chemical signaling to cells: hormones, neurotransmitters
- Dissipation of heat: delivery of heat from core to body surface
- Mediation of inflammatory and host defense responses
Transport in the cardiovascular system: Simplified version of the entire crdvscr syst:
,Facts
1. Heart:
- Beats 70x/min, 2.3 billion times in a lifetime
- Weighs ~ 300 grams
- Pumps 71 ml/beat, 5-25 L/min, 7200 L/day, 400 million L/life
2. Vessels:
- 0.006 - 35 mm in diameter
- Total length 100000 km
3. Blood:
- 300 - 400 mL (baby) to 5 L (adult)
- Average speed 11 km/h, one round in 22 seconds
- Completely replaced in 1 week
Hemodynamics
1 mmHg = 133.32 Pa
Pressure
Three ways of exerting pressure in tubes:
1. Driving pressure - axial
- Pressure difference between the arterial and venous ends of the circulation.
- Only generator of blood flow when the vascular system is viewed horizontally.
2. Transmural pressure - radial
- Pressure difference between inside (lumen) and outside vessel (interstitial)
- Governs vessel diameter → determines resistance R
3. Hydrostatic pressure - vertical
- Pressure difference between different height locations
- Exists even in the absence of blood flow
-
Pressure (difference) law, also called the Ohm’s law of hemodynamics:
- P = Pressure difference
- F = Flow ( volume/time)
- R = Resistance
Pressure formula :
- P = Pressure
- p = density of liquid in the column
- g = gravitational constant
- h = height of column
,Flow
Main formula for total flow calculation:
- CO = Cardiac Output (total blood flow in circulation)
- SV = Stroke Volume (output during single heartbeat)
- HR = Heart Rate
CO ~ 5L/min at rest
Flow the displacement of volume (ΔV) per unit time (Δt), also the
movement of fluid with cross-section area A with mean velocity v.
Poiseuille’s law:
Flow of fluid with viscosity η in a straight, rigid, cylindrical tube of
radius r and length L:
Conditions for Poiseuille’s law:
- The fluid must be incompressible.
- The tube must be straight, rigid, cylindrical, unbranched and have
a constant radius.
- The velocity of the thin fluid layer at the wall must be zero (no “slippage”)
- The flow must be laminar (i.e. flowing smooth paths in layers)
- The flow must be steady (i.e. not pulsatile → flow with periodic variations)
- The viscosity of the fluid must be constant
Viscosity = Property of the fluid, expressing the degree of lack of slipperiness in the fluid. In
cylindrical vessels, viscosity results in a bullet-like velocity/flow profile.
Unit: Pa.s or Poise or cP (centi Poise)
- 1 cP = 0.01 Poise = 0.001 Pa.s = 1 mPa.s\
Examples:
- Water (20 C): 1 cP
- Blood (37 C): 3.2 cP
- Olive oil: 80 cP
- Honey : 2000 - 10000 cP
, Terminology
Hemodynamics → The study of the forces involved in the circulation of blood.
Cardiovascular system → The anatomical system consisting of the heart and blood vessels.
Pulmonary circulation → Of or relating to, or affecting the lungs.
Systemic circulation → Of or relating to systems or a system.
Volatile → Evaporating readily at normal temperatures and pressures.
Venous → Dark, no oxygen
Arterial → Bright, oxygen rich
Transmural → Existing or occurring across the entire wall of an organ or
blood vessel.
Hydrostatic → Relating to or denoting the equilibrium of liquids and the pressure
exerted by liquid at rest.
Rigid → Not flexible or pliant.
- The Cardiovascular system and Hemodynamics -
Functions of the cardiovascular system:
1. Primary:
- Distribution/transport of dissolved gasses and other molecules for nutrition,
growth and repair
2. Secondary:
- Fast chemical signaling to cells: hormones, neurotransmitters
- Dissipation of heat: delivery of heat from core to body surface
- Mediation of inflammatory and host defense responses
Transport in the cardiovascular system: Simplified version of the entire crdvscr syst:
,Facts
1. Heart:
- Beats 70x/min, 2.3 billion times in a lifetime
- Weighs ~ 300 grams
- Pumps 71 ml/beat, 5-25 L/min, 7200 L/day, 400 million L/life
2. Vessels:
- 0.006 - 35 mm in diameter
- Total length 100000 km
3. Blood:
- 300 - 400 mL (baby) to 5 L (adult)
- Average speed 11 km/h, one round in 22 seconds
- Completely replaced in 1 week
Hemodynamics
1 mmHg = 133.32 Pa
Pressure
Three ways of exerting pressure in tubes:
1. Driving pressure - axial
- Pressure difference between the arterial and venous ends of the circulation.
- Only generator of blood flow when the vascular system is viewed horizontally.
2. Transmural pressure - radial
- Pressure difference between inside (lumen) and outside vessel (interstitial)
- Governs vessel diameter → determines resistance R
3. Hydrostatic pressure - vertical
- Pressure difference between different height locations
- Exists even in the absence of blood flow
-
Pressure (difference) law, also called the Ohm’s law of hemodynamics:
- P = Pressure difference
- F = Flow ( volume/time)
- R = Resistance
Pressure formula :
- P = Pressure
- p = density of liquid in the column
- g = gravitational constant
- h = height of column
,Flow
Main formula for total flow calculation:
- CO = Cardiac Output (total blood flow in circulation)
- SV = Stroke Volume (output during single heartbeat)
- HR = Heart Rate
CO ~ 5L/min at rest
Flow the displacement of volume (ΔV) per unit time (Δt), also the
movement of fluid with cross-section area A with mean velocity v.
Poiseuille’s law:
Flow of fluid with viscosity η in a straight, rigid, cylindrical tube of
radius r and length L:
Conditions for Poiseuille’s law:
- The fluid must be incompressible.
- The tube must be straight, rigid, cylindrical, unbranched and have
a constant radius.
- The velocity of the thin fluid layer at the wall must be zero (no “slippage”)
- The flow must be laminar (i.e. flowing smooth paths in layers)
- The flow must be steady (i.e. not pulsatile → flow with periodic variations)
- The viscosity of the fluid must be constant
Viscosity = Property of the fluid, expressing the degree of lack of slipperiness in the fluid. In
cylindrical vessels, viscosity results in a bullet-like velocity/flow profile.
Unit: Pa.s or Poise or cP (centi Poise)
- 1 cP = 0.01 Poise = 0.001 Pa.s = 1 mPa.s\
Examples:
- Water (20 C): 1 cP
- Blood (37 C): 3.2 cP
- Olive oil: 80 cP
- Honey : 2000 - 10000 cP
, Terminology
Hemodynamics → The study of the forces involved in the circulation of blood.
Cardiovascular system → The anatomical system consisting of the heart and blood vessels.
Pulmonary circulation → Of or relating to, or affecting the lungs.
Systemic circulation → Of or relating to systems or a system.
Volatile → Evaporating readily at normal temperatures and pressures.
Venous → Dark, no oxygen
Arterial → Bright, oxygen rich
Transmural → Existing or occurring across the entire wall of an organ or
blood vessel.
Hydrostatic → Relating to or denoting the equilibrium of liquids and the pressure
exerted by liquid at rest.
Rigid → Not flexible or pliant.
