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.
Do veins carry high pressure Blood and what is the structure of the wall?
Veins do not carry high pressure blood so their walls tend to be thinner; although, they still contain smooth muscle and are capable of vasoconstriction.
At rest, ____of our total blood volume is in the ________of the circulation
At rest, 65% of our total blood volume is in the venous half of the circulation
Why are veins called capacitance vessels?
When veins constrict, they rapidly return blood to the heart, increasing venous return and cardiac output.
What are the three body structures that assist the vein in taking blood back to the heart?
One-way valves, skeletal muscle contraction, and changes (decrease) in thoracic pressure due to respiration assist in venous return.
Capillaries are ________ exchange vessel
Capillaries are low-pressure exchange vessel
Capillary walls consist only of?
Their walls consist only of simple squamous epithelia and its basal membrane, and often their lumen diameter is only wide enough for a single RBC to pas
Most capillary walls contain small pores called ___________and what does it allow for?
The capillary walls contain small pores called fenestrations. These fenestrations allow small molecules to diffuse through the wall. However, blood cells and larger molecule are not allowed.
In the tissues, _______ and _______ are allowed to diffuse out of the capillary, through the _______, and into the cell
In the tissues, oxygen and nutrients are allowed to diffuse out of the capillary, through the interstitial fluid, and into the cell
In the lungs, _______diffuses out of the capillaries and ______ diffuses in
In the lungs, carbon dioxide diffuses out of the capillaries and oxygen diffuses in
Pressure in the cardiovascular system is measured in ?
millimetres of mercury (mmHg)
Do we spend more time in Diastole or systole?
Diastole: we spend more time filling the heart than contracting.
MAP = __ x ___
CO x TPR
TPR is determined by the ________, where _________ increases TPR and __________decreases it.
TPR is determined by the arteriole diametre, where vasoconstriction increases TPR and vasodilation decreases it.
An increase in blood viscosity (thickness) does what to TPR?
An increase in blood viscosity (thickness) also increases TPR
Pulmonary HTN is what?
, which is high pressure within the pulmonary arteries, creates high afterload for the right ventricle.
What system of the body controls HR and SV
HR- SNS and PSNS, SV: Antidiuretic hormone (ADH)
An increased SVR can be caused by
An increased SVR can be caused by vasoconstrictors, hypovolemia, or late septic shock
A decreased SVR can be caused by
early septic shock, vasodilators, morphine, nitrates, or hypercarbia(elevated C02 in the blood).
How does the SNS control the HR, what neurotransmitters does it release?
The SNS releases the neurotransmitter norepinephrine (NE) from its postganglionic neurons, as well as, epinephrine (E) into the blood stream
alpha a-adrenergic receptors are found primarily in the?
alpha a-adrenergic receptors that are primarily in blood vessel?
B1-adrenergic receptors are in the?
B1-adrenergic receptors are in the heart and juxtaglomerular cells of the kidney
B2-adrenergic receptors are found in?
B2-adrenergic receptors that are found in the vessels of the limbs and heart.
Both NE and E bind to several plasma membrane receptors what are they?
Both NE and E bind to several plasma membrane receptors; 1) a-adrenergic receptors that found primarily in blood vessels, 2) B1-adrenergic receptors that are found in the heart and juxtaglomerular cells of the kidney, and 3) B2-adrenergic receptors that are found in the vessels of the limbs and heart.
Stimulating the __________ receptors in the heart causes an increase in the rate and force of contraction, while stimulating the __________ receptors in the arterioles causes vasoconstriction. __________stimulation causes vasodilation
Stimulating the B1-adrenergic receptors in the heart causes an increase in the rate and force of contraction, while stimulating the a-adrenergic receptors in the arterioles causes vasoconstriction. B2-adrenergic stimulation causes vasodilation
The PSNS releases what neurotransmitter and what receptor does it bind to? and what happens when that receptor is stimulated.
PSNS: The PSNS releases the neurotransmitter acetylcholine that binds to a plasma membrane receptor called the muscarinic receptor. . Stimulation of the muscarinic receptor causes a decrease in heart rate
Acetylcholine also triggers the release of ______ causing vasodilation.
Acetylcholine also triggers the release of nitric oxide causing vasodilation.
During Infusion of epinephrine what receptors are predominantly activated?
Infusion of epinephrine predominantly activates the B-receptors
What is the mechanism of action for B1-receptors when activated?
B1 activation increases the heart rate and cardiac contractility resulting in a moderate increase in systolic pressure.
What is the mechanism of action for B2-receptors when activated?
B2 activation causes vasodilation to the limbs reducing peripheral resistance and mildly decreasing diastolic pressure.
When norepinephrine is infused what receptors are stimulated and what is the mechanism of action.
infusion of norepinephrine also activates the B1 receptors and increases cardiac output, but norepinephrine also activates the a- receptors in the systemic arteriole.. This results in large increases in peripheral resistance, systolic and diastolic pressure
What are the stretch receptors called and where are they located? what do they also detect.
Stretch receptors in the carotid sinus and the aortic arch detect changes in blood pressure. These stretch receptors are called baroreceptors
What is the mechanism of action of the neural control of blood pressure?
An elevation in blood pressure stretches the baroreceptors, which send sensory impulses to the cardiovascular center in the medulla. This decreases the SNS and increases the PSNS to lower the CO and TPR, returning the BP to normal.
What system does the Renal Control of Blood Pressure use?
RAAS Renin-Angiotensin-Aldosterone System
How does the kidney influence blood pressure?
The kidneys influence blood pressure by regulating blood volume and by producing the enzyme renin
(Renal Control of Blood Pressure)How does the SNS respond to a large decrease in arterial blood pressure?
SNS stimulation in response to a large decrease in arterial blood pressure causes constriction of the afferent renal arteriole and reduces filtration and the production of urine
(Renal Control of Blood Pressure) What does B1 stimulation increase the production of?
B1 stimulation increases the secretion of renin. Renin converts angiotensinogin to angiotensin I, which is activated by ACE to produce angiotensin II
