Lecture 23 10/17/23 Flashcards
What is the function of the CV system?
circulate blood at rates that meet metabolic demand while maintaining adequate perfusion and low filling pressures
What does blood contain?
-nutrients/waste
-gases
-electrolytes
How is oxygen bound to hemoglobin conveyed?
from the lungs to the metabolizing tissues
How is CO2 conveyed?
from the metabolizing tissues to the lungs
How do gases, nutrients, and wastes move?
via diffusion
What are the characteristics of blood flow?
-pulsatile
-established by cyclic mechanical activity of heart
What are the two “pumps” of the heart?
-pumping blood through the systemic vascular bed
-pumping blood through the pulmonary vascular bed
What is the stroke volume?
the volume of blood that the ventricle ejects each systole
What is cardiac output?
the volume of blood that leaves one side of the heart in one minute
Why is it important that the cardiac output of the left and right heart are equal over time?
don’t want one side of the heart to fall behind
What are the different structures in the heart?
atria
-valves
-ventricles
What are AV valves?
valves guarding the entrances to the ventricles
What are semilunar valves?
valves guarding the entrances to the great arteries
When are AV valves open and closed?
open: during filling/diastole
closed: contraction/systole
When are the semilunar valves open and closed?
open: during contraction/systole
closed: filling/diastole
What is the function of ventricles, in general?
propel the stroke volume into the respective vascular bed
What are the characteristics of the right ventricle?
-thin-walled
-pyrimidal
-“volume pump”
-geometrically suited for low resistance/low pressure
What are the characteristics of the left ventricle?
-cylindrical
-“pressure pump”
-generates high pressures
What is the vasculature?
branching system of vessels that conveys blood and provides a site for metabolite exchange
What is the role of veins/venules?
convey blood to the heart
What is the role of arteries/arterioles?
convey blood away from heart
What is the role of capillaries?
metabolite exchange
What is the main role of arteries?
conduits
What is the main role of arterioles?
resistance vessels that determine distribution of cardiac output
What is the main role of venules?
convey blood from capillaries to veins
What are the roles of veins?
-conduits
-reservoirs
What type of artery is the aorta?
elastic
What type of artery are most arteries?
muscular
What does the arteriole wall consist of?
smooth muscle
What are capillaries?
single layer of endothelial cells
What substances are in the walls of veins?
-smooth muscle
-small amounts of elastin and collagen
How is blood flow to the tissues controlled?
through changes in local resistance
How does venous return impact cardiac output?
increased venous return = increased cardiac output
Why is arterial pressure regulation independent of local blood flow and cardiac output?
because maintaining normal blood pressure is the “priority” of the CV system
How does vasoconstriction function?
-increases resistance
-decreases flow
How does vasodilation function?
-decreases resistance
-increases flow
What are the characteristics of pressure?
-force/area
-measured in mmHg
What are the characteristics of systemic circulation oxygen levels and pressure?
-high O2
-high pressure
What are the characteristics of pulmonary circulation oxygen levels and pressure?
-low O2
-low pressure
Where is the greatest proportion of blood volume contained?
systemic veins
What should venous pressure normally be?
near 0 mmHg
What is resistance?
measure of opposition to electrical current/flow
How does change in pressure relate to cardiac output and resistance??
/\P = CO x R
What two factors are the determinants of resistance?
-radius (most important)
-viscosity
What is resistance, in terms of forces?
the sum of forces that must be overcome for a pressure difference to establish flow
Why is systemic arterial pressure greater than pulmonary arterial pressure?
because systemic vascular resistance is greater than pulmonary vascular resistance
What does venous return result from?
-energy imparted by ventricular ejection
-muscular pump
-ventricular suction
What is laminar flow?
smooth flow (river)
What is turbulent flow?
-high velocity flow (fast stream)
How do velocity and viscosity relate?
-high velocity, low viscosity
-high viscosity, low velocity
