Hemodynamics Flashcards
Vasculature:
All blood vessels.
Blood flows through the vasculature in a circuit.
Circuit:
A network of blood vessels that begins and ends at the heart.
The sum of resistance of all vessels in the circuit.
Types of vasculature/Circuits:
Pulmonary circuit.
Systemic circuit.
Pulmonary Circuits:
Includes blood vessels within the lungs, and those that transport blood between the heart and lungs.
Systemic Circuits:
Includes blood vessels within all other organs and those that transport blood between the heart and those organs.
Type of blood vessels:
Arteries.
Arterioles.
Capillaries.
Venule.
Veins.
Series Flow:
The flow of blood through different blood vessels in sequence.
Parallel Flow:
Movement of blood through different organs at the same time.
Blood flow:
The rate at which blood moves through the vasculature.
(ml/min).
This measures the efficiency of blood flow to and from the organs.
Determinants of blood flow:
Pressure difference & Vascular resistance.
The pressure difference (mmHg):
The force that drives blood through the circuits.
_____ drives flow through the pulmonary circuit.
The right ventricle.
_____ drives flow through the systemic circuits.
The Left ventricle.
Pressure at the start of a circuit is _______ than the pressure at the end of a circuit.
HIgher.
Pressure difference in the pulmonary circuit:
15 mmHg.
Pressure difference in the systemic circuits:
95 mmHg.
Vascular resistance:
An impediment to blood flow.
Resistance is a measure of how much friction is encountered by blood as it moves through the vasculature.`
Flow (Q) is the same in both:
Pulmonary & Systemic circuits.
Resistance is higher in _____:
Systemic circuit.
Resistance in a single blood vessel:
Length.
Viscosity.
Radius.
Viscosity of blood is affected by:
Hematocrit.
Directly proportional.
What increase would increase resistance:
Length & Viscosity.
What increase would decrease resistance:
Radius.
What increase would increase blood flow:
Radius and pressure difference.
What increase would decrease blood flow:
Length and Viscosity.
Poiseuille equation for resistance:
The relationship between blood flow, length, radius, and viscosity.
Total peripheral resistance or Systemic resistance:
Resistance in a systemic circuit.
19 mmHg/L/min.
Pulmonary vascular resistance:
Resistance in the pulmonary circuit.
3 mmHg/L/min.
Arterioles in the TPR:
Resistance of the arterioles is the main source of resistance.
It accounts for 60% of resistance in the Systemic circuit.
Why is PVR lower than TPR:
The pulmonary circuit is shorter.
The PVR also lacks smooth muscles.
Arterioles:
Small arteries that lead into capillaries.
