Perfussin and Hemodynamics D3 Flashcards
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CO =
HR x SV
Example of resting CO:
60 beats/minute x 0.1 L/beat = 6 L/minute
Define cardiac output (CO)?
is the amount of blood pumped by the ventricle in one minute
Any factor affecting the heart rate or stroke volume will affect cardiac output: True or False
True
HR is responsive to what systems and what controls the HR?
Heart rate is responsive to SNS and PSNS tone, and controlled by the cardiovascular control centre in the medulla, the hypothalamus, and to some degree by the motor cortex
Define stroke volume?
Stroke volume is the amount of blood ejected from the ventricle with each contraction
Stroke volume is determined by what?
It is determined by the amount of filling or venous return, and the force of ventricular contraction or contractility and blood volume.
Preload is described as what and is determined by what?
Described as the filling force applied to the heart. Preload is largely determined by the venous return to the heart
Describe the Frank-Starling mechanism?
When more blood is returned to the heart, the heart stretches and generates more force to effectively pump the increased load. The more tension or stretched the heart is the stronger the contraction (more oxygen efficient than increasing HR)
What can be seen when our preload is excessive?
The jugular vein is engorged.
What is the function of the Baroreceptors to the HR?
Stimulate the HR to increase when low using the SNS
Stimulate the HR to reduce when high using the PSNS
Describe Afterload?
Described as the pressure the ventricle must overcome to eject blood into the arteries. The load or pressure which the heart has to overcome to push or overcome in order to move blood around the circuit and out of the heart.
Describe the structure and function of arteries.
Arteries are muscular blood vessels that maintain blood pressure throughout the body.
Larger arteries, such as the aorta contain large amounts of ______ which allows them to ________ and _______ the changes in________.
Larger arteries, such as the aorta contain large amounts of elastin which allows them to withstand and ‘smooth out’ the changes in pressure.
Define pulse pressure?
Pulse pressure is the difference between systolic and diastolic pressures in the arteries.
Arterioles can dramatically alter the blood pressure and control the local blood flow through an area of the bod by doing what and the often referred to as what?
. By vasoconstricting (ie. Contracting) and vasodilating (ie. Relaxing), arterioles can dramatically alter the blood pressure and control the local blood flow through an area of the body. Arterioles are often referred to as the resistance vessels.
What are the three layers of the artery and describe their structure?
Tunica intima: innermost layer of the artery wall. Thin layer of endothelial cell
Tunica media: middle layer of the artery wall, composed of smooth muscle that can constrict and dilate to change the artery’s diameter, autonomic nerves (sympathetic & parasympathetic)
Tunica externa: outermost covering of artery wall, also called tunica adventitia, composed of connective tissue that provides support for the artery
What blocks the arteries from constricting?
Calcium channel blocker (CCB) medications block vasoconstriction of arteries
In the artery what happens when blood flows flows from an area of larger vessel diameter to an area of smaller vessel diameter?
When blood flows from a larger area of vessel diameter to a smaller are of vessel diameter, pressure increases in the vessel
Define Peripheral Vascular resistance (PVR)
the resistance caused by the blood vessels within the circulatory system
mainly influenced by the diameter of arterial blood vessel, diameter regulate by autonomic nervous system
What is the PVR mainly influenced by?
mainly influenced by the diameter of arterial blood vessel, diameter regulate by autonomic nervous system
Describe Ejection fraction (EF%)
Ejection fraction is a measurement of the percentage of blood leaving your heart each time it contracts
What is the normal percentage of the blood that is pumped out or ejected in every contraction?
60-65%
Define Cardiac contractility?
Refer to the myocardium ability to stretch and contract in response to the filling of the heart with blood.