CV Final Flashcards
Arterioles have the greatest what?
resistance to bloodflow
Vein function?
Capacitance function (blood volume)
Distension of the aorta and its branches during?
Systole
• Elastic recoil of the large arteries with forward propulsion of blood during ventricular relaxation during?
Diastole
Velocity of blood flow is __________ related to the cross-sectional area of the vascular system
Inversely.
Blood flow velocity is very slow in the capillaries
The cardiac output is controlled mainly by the sum of?
all the local tissue flows
Cardiac accelerators
Sympathetic
T1-T4
Stellate ganglia (cervicothoracic ganglia) and middle cervical ganglia
Parasympathetic
– Much innervation to SA and AV nodes
– Little innervation to ventricles
Pericardium Layers
– Fibrous
– Serous
• Parietal layer
• Visceral layer
Potassium is the major determinant of the _________ ________ _______
Resting Membrane Potential
As K+ leaves cell, ________ increases on the inside of the cell membrane and __________ attracts K+
negativity, electrostatically
Na+, K+ - ATPase Pump Ratio
Pumps in 3:2 ratio (3 Na+ out: 2 K+ in)
PHASES OF THE FAST RESPONSE ACTION POTENTIAL
- Phase 0 = Depolarization
- Phase 1 = Partial Repolarization
- Phase 2 = Plateau
- Phase 3 = Repolarization
- Phase 4 = Resting Membrane Potential
ERP & RRP
ERP = Effective Refractory Period (cannot regenerate another action potential)
RRP = Relative Refractory Period (can begin to generate another action potential)
Phase 0
• The characteristics of the upstroke of the action potential depend almost entirely on inward movement of Na+
There is a small inward Ca++ current (important for contraction)
PHASE 1 – Partial Repolarization
Inactivation of Na+ channels ends
Transient outward K+ current
PHASE 2 - Plateau
What produces the plateau?
Slow inward Ca++ currents (L-type calcium channels)
Counterbalanced by:
Outward K+ currents
PHASE 3 - Repolarization
What outward movement is mainly responsible for repolarization?
K+
Na+ channel recovery begins during Relative Refractory Period
PHASE 4 – Resting Membrane Potential
- Restoration of ionic concentrations
- Na+,K+-ATPase
- Na+-Ca++ Exchanger (driven by gradients not electrical)
- ATP-driven Ca++ Pump
• The ability of a focal area of the heart to generate pace making stimuli is known as?
Automaticity
Calcium-Induced Calcium Release (CICR)
Because the T-tubules are continuous with the extracellular fluid, extracellular concentration of calcium becomes important for adequate heart contraction.
8 ECG Waves Intervals & Segments
Page 8
Ventricular Systole Phases
– Phase 2
Isovolumic contraction
– Phase 3 Rapid ejection (70% of ventricular volume is ejected)
– Phase 4
Reduced ejection
• Ventricular Diastole Phases
– Phase 5 Isovolumic relaxation
– Phase 6
Rapid filling
– Phase 7
Diastasis
– Phase 1
Atrial systole
Determinants of CO
Heart Rate
Contractility
Preload
Afterload
• Changes in heart rate alone inversely affect?
Stroke Volume
Effects of Heart Rate on Cardiac Output
Bowditch (Treppe) Effect
- An increase in heart rate will also cause positive inotropy (Bowditch effect, Treppe or “staircase” phenomenon).
- This is due to an increase in intracellular Ca++ with a higher heart rate
• Preload can be defined as?
the initial stretching of the cardiac myocytes prior to contraction. It is related to the sarcomere length at the end of diastole.
indirect indices of preload?
– LVEDV (left ventricular end-diastolic volume)
– LVEDP (left ventricular end-diastolic pressure)
– PCWP (pulmonary capillary wedge pressure)
– CVP (central venous pressure)
What is the Frank Starling Mechanism
The heart pumps the blood that is returned to it
Increasing venous return and ventricular preload leads to an increase in stroke volume.
What is afterload?
the “load” that the heart must eject blood against.
Afterload increased by?
Increased aortic pressure
Increased systemic vascular resistance
Aortic valve stenosis
Ventricular dilation
La Place and Afterload
– LaPlace’s Law: Wall stress = Pr/h
P = ventricular pressure
R = ventricular radius
h = wall thickness
What affects the FSC the most?
Changes in afterload and inotropy
Spontaneous respiration and venous return
– Decreased intra-thoracic pressure results in a decreased right atrial pressure which enhances venous return
Mechanical ventilation and venous return
– Increased intra-thoracic pressure during positive-pressure lung inflation causes increased right atrial pressure which decreases venous return
Valsalva Maneuver and venous return
– Causes a large increase in intra-thoracic pressure which impedes venous return to the right atrium
As the PRA starts to fall below zero what happens to CO
the CO begins to level off because the vena cava collapses, thus limiting venous return to the heart.
Experimentally, if cardiac output is stopped, aortic pressure falls and PRA increases to a common value of about ___ mmHg
8 (Mean Circulatory Filling Pressure)
Pmc
Venous return curves
pg.15
EF =
SV/EDV
SV=EDV-ESV
the width of a pressure volume loop represents the difference between _______ and ________
EDV and ESV, which is by definition the stroke volume (SV). The area within the loop is the ventricular stroke work.
Pressure Volume loop Phases
Slide 17
ability of the heart to change its force of contraction and therefore stroke volume in response to changes in venous return is called?
the Frank-Starling mechanism (or Starling’s Law of the heart).
. Myocyte stretching increases the ______ _______, which causes an increase in force generation
sarcomere length
Velocity is _______ _______ to cross-sectional area
inversely related
• Flow, which is ______ ______ _____, must be distinguished from velocity, which is distance per unit time.
volume per unit time
Flow = velocity x cross sectional area of the vessel
pg. 19 diagram
Blood pressure is
the force exerted by the blood against any unit area of the vessel wall
What is perfusion pressure?
perfusion pressure (i.e., pressure gradient) that is normally represented by the difference between the arterial and venous pressures across the organ.
Cerebral Perfusion Pressure
– Mean arterial pressure – CVP or ICP (whichever is higher)
Coronary Perfusion Pressure
– Diastolic pressure - LVEDP
Poiseuille’s Law
• Flow is directly proportional to the pressure gradient
• Flow varies directly as the fourth power of the radius
o Doubling the radius of a tube causes a 16-fold increase in flow
• Flow is inversely proportional to the viscosity of the fluid
• Flow is inversely proportional to the length of the tube
What is resistance?
Resistance = the impediment to blood flow in a vessel and cannot be measured by any direct means
SVR formula
MAP-CVP/CO *80
Normal SVR = 700-1600
Resistance in series
Resistance in parallel
Resistance in Series is Additive
Resistance in Parallel has a decreased resistance by increasing the overall radius
the best transducer placement for standard clinical monitoring is at a vertical height approximately
5 cm below the left sternal border at the fourth intercostal space.
Thermodilution Pac: Cardiac output is _______ _______ to the area under the curve (AUC)
inversely proportional
MAP equation
SBP + DBP(2)/3
% of the blood volume may be stored in the veins
70
Arterioles are the ________ of the circulation
“Stopcocks”
True capillaries are devoid of smooth muscle and are_____of active constriction
incapable
Diffusion through Capillary Membrane
pg. 23
Iv Fluid and TBW
pg 24
– Capillary hydrostatic pressure, Interstitial fluid hydrostatic pressure, & interstitial fluid osmotic pressure ALL MOVE FLUIDS?
OUTWARD FROM THE CAPILLARY
– Plasma colloid osmotic pressure is the only major factor that moves fluid?
INTO THE CAPILLARY
Tissue Metabolic Activity Is the Main Factor in Acute Control of what?
of Local Blood Flow
What is the metabolic Mechanism?
Any intervention that results in an inadequate oxygen (nutrient) supply for the metabolic requirements of the tissues results in the formation of vasodilator substances which increase blood flow to the tissues.
What is Reactive Hyperemia
= when blood supply is blocked to a tissue for a few seconds to as long as an hour or more and then is unblocked, blood flow through the tissue usually increases immediately to 4-7 times normal for a few seconds to many hours
What is auto regulation?
Intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure
Autonomic Nervous system control: Two sources and their neurotransmitters are?
Sympathetic Nerves
– Norepinephrine released
Adrenal Gland (longer lasting effect)
– Releases mostly epinephrine (80%)
– Lesser amount of norepinephrine released (20%)
A1
Vasoconstriction
Beta 1
Increased heart rate & Contractility
Beta 2
– Vasodilation – Bronchodilatation – Uterine relaxation – Glycogenolysis – Drive Potassium into the cells (repeated albuterol treatments)
Baroreceptor Reflex is Responsible for?
Rapid Adjustments of Blood Pressure
Carotid Sinus and Aortic Arch Baroreceptors
Senses and buffers changes in blood pressure
– Works in both directions
Diving Reflex =
water on the face causes vasoconstriction and slowing of the HR
CNS Ischemic Response
Cushing Response = hypertension with bradycardia
Bezold-Jarisch Reflex
This reflex plays a role in blood pressure regulation
Hypotension with Bradycardia / parasympathetic response
– (Ventricular Receptor Reflex)
Empty Ventricle
Bainbridge Reflex
increase in volume causes sympathetic response- inc. HR
Low pressure receptors that respond to stretch
Sense cardiovascular system volume
The heart extracts _______to a ______ ______ than any other organ
oxygen, greater extent
Abrupt pressure rise (80-90% of LV flow occurs when?
early diastole
The __________ is more susceptible to ischemia than the midmyocardium or subepicardium
subendocardium
Epicardial coronary stenoses are associated with reductions in the?
subendocardial to subepicardial flow ratio
The ultimate cause of Myocyte death in myocardial ischemia
Intracellular Ca+ overload leads to impaired contraction and cell death.
Decrease Na/Ca exchange
what is ischemic preconditioning
brief periods of ischemia appear to “precondition” myocardium against reversible or irreversible tissue injury, including stunning, infarction, and the development of malignant ventricular arrhythmias
The valve area in regurgitant lesions can respond to?
changes in loading conditions (respond to changes in preload, afterload)
AS Presenting symptoms and life span
– Angina = 5 years
– Syncope = 3 years
– CHF = 2 years
Valve Pathology
pg. 39-42
