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Pathophysiology (ch 12-cardiovascular disorders)
Terms in this set (60)
-Located in the mediastinum
-Located in the pericardial sac
Epicardium (visceral pericardium)
look at first 3 slides-review of structures
Review: Cardiac Cycle
Relaxation of myocardium required for filling chambers
Contraction of myocardium provides increase in pressure to eject blood
Cycle begins with
Atria relaxed, filling with blood - AV valves open - blood flows into ventricles - atria contract, remaining blood forced into ventricles - atria relax - ventricles contract - AV valves close - semilunar valves open - blood into aorta and pulmonary artery - ventricles relax
look at slide 7 for pic**!!
Review: Heart Sounds
"Lubb" - closure of AV valves
"Dubb" - closure of semilunar valves
Caused by incompetent valves or holes in the septum
Indicates heart rate
Abnormal- Difference in rate between apical & radial pulse- the pulse is not reaching the periphery
Review: Conduction System
SA node: (60-100bpm)
Located in the floor of right atrium
AV bundle (bundle of His)
Right and left branches
Depolarization of atria
Depolarization of ventricles
Repolarization of ventricles
Abnormal ECG = arrhythmias/dysrhythmias
Infarct or systemic problem (e.g. K+ deficiency)
Control of the Heart
Cardiac control center in medulla
Controls rate and force of contraction
Detect changes in blood pressure
Located in the aorta and internal carotid arteries
Sympathetic stimulation (cardiac accelerator nerve)
Increases HR (tachycardia) via epinephrine stimulation of beta1-adrenergic receptors
Parasympathetic stimulation (CN X vagus nerve)
Decreases heart rate, HR (bradycardia) via ACh (opens K+ channels= hyperpolarize
Factors that Increase Heart Rate
Increased thyroid hormones or epinephrine
Epinephrine stimulates b-receptors increases both HR & contractility.
T3 increases speed of diastolic relaxation (because it increases # of Ca++ ATPase pumps in SR, making pumping more efficient)
Elevated body temperature, infection
Increased environmental temperature
Especially in high humidity; blood vessels dilate and the heart has to pump faster to maintain blood pressure
Exertion or exercise
Smoking: Speeds up atherosclerosis & damages blood vessels= "Peripheral Arterial Disease" can reduce blood circulation (and can result in blood clots)
Nicotine- Increases BP making your heart work harder
Carbon Monoxide- Poison that replaces O2 in your blood making your heart beat faster
Tar- Coats lungs making it harder to breathe; carcinogen (increased risk of lung cancer)
Stress response (emotional or physical)
Pregnancy: Faster HR due to increased # of blood vessels, increased BMR, and increased body strain
What do beta blocker drugs do?
Prevent SNS stimulation of heart preventing increase in HR & contractility
Useful after heart has been damaged (gives the heart a break)
Won't speed up, won't increase force of contraction
Left coronary artery divides into:
Left anterior descending or interventricular artery
Left circumflex artery
Right coronary artery branches into:
Right marginal artery
Posterior interventricular artery
Right & Left Coronary Arteries
Branch off aorta immediately distal to aortic valve
Part of systemic circulation
Blood flow greatest during diastole
Collateral circulation extremely limited - Anastomoses near apex.
look at slide 15
Anastomosis- Connection between branches of two arteries
-Provide collateral circulation (to the apex of the heart)
Right coronary artery nourishes:
-SA node in >50% of population
-AV node in ~100% of population
Right coronary artery blockage= Conduction disturbances!
Left coronary artery blockage= impair left ventricle pumping= congestive heart failure
Exercise increases the amount of collateral circulation in your heart
-We are all building up atherosclerosis :'(, so the building of collateral circulation is very PREVENTATIVE and good
What information does the ECG provide about heart function?
Can tell if there are cardiac conduction problems, atria/ ventricle contraction problems
Describe the function of the areas of the heart usually supplied by the left coronary artery.
Left atrium and ventricle, sometimes the SA node
Describe the effect if: a) the atria were to contract at the same time as the ventricles, or b) if the ventricles contracted slightly before the atria.
Decreased amount of blood filling the ventricles and less blood being ejected from the ventricles; some blood would remain in the atria
Why is collateral circulation important?
Provides an alternate route for blood glow around an obstruction by directing connection between 2 blood vessels or by opening up capillaries from another nearby artery into the deprived area
Why is there a pause after atrial contraction & before ventricular contraction?
To allow for blood to empty from the atrium into the ventricle
Predict the outcome if more blood is pumped into the pulmonary circulation than into the systemic circulation during each cardiac cycle.
Eventually there would be excessive blood and congestion in the pulmonary circulation
Cardiac Output (CO)= Q
Blood ejected by a ventricle in one minute
CO = SV × HR (heart rate)
Stroke Volume (SV)
Volume of blood pumped out of ventricle/contraction
Amount of blood delivered to heart by venous return
Force required to eject blood from ventricles
Determined by peripheral resistance in arteries
Starling's Law: Increasing the end diastolic volume will automatically result in a corresponding increase in stroke volume
More full- eject more stroke volume, Less full- eject less stroke volume
Predict which organs would have a large capillary network.
Skeletal muscle, liver
Explain how venous return increases with exercise and the purpose of such action.
Skeletal muscle activity
Valves in veins
What is cardiac reserve?
Basically the difference between resting CO and maximum CO
Usually about 4-5x rest (70bpm x 70mL/beat at rest)
During inspiration, pressure in thoracic cavity drops
→ pressure in veins in thorax
Skeletal muscle can pump the blood against gravity
When pressure increases, volume goes down
It is easy for blood to enter a place of low pressure
Exerted when blood is ejected from ventricles (high)
Sustained pressure when ventricles relax (lower)
Blood pressure (BP) is altered by CO, blood volume, & PR.
PR- Peripheral resistance
PR increase, BP increase
-More pressure is needed because of the greater resistance
BV increase, BP increase
CO increase, BP increase
Review: What is the relationship between PR, BP and blood flow?
Flow = 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒/𝑅𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒
Blood pressure = 𝐹𝑙𝑜𝑤 (𝐶𝑂) 𝑥 𝑃𝑅
Blood Pressure (cont.)
Changes in blood pressure:
Sympathetic branch of ANS
epinephrine & norepinephrine stim. a1-adrenergic receptors in arteriolar walls & stim. b1-adrenergic receptors in heart increasing HR & contractility.
Increased output → vasoconstriction, ↑ venous return & ↑ BP
Decreased output → vasodilation & decreased BP
BP is directly proportional to blood volume.
Hormones that increase BV & therefore BP:
Antidiuretic hormone (↑ blood vol., vasoconstriction, & BP);
Aldosterone (↑ blood volume, ↑ BP);
Renin-angiotensin-aldosterone (vasoconstriction ↑ BP)
look at slide 25-30**
Explain 4 factors that can increase BP.
Increased vasoconstriction, venous return, (coticosteroids, atherosclerosis, smoking), BV, viscosity
Reduced activity of baroreceptors
Decreased PNSN, diameter of blood vessels, elasticity of blood vessels
Increase HR, increase contractility, increase blood volume
List the compensatory mechanism (in the correct sequence) that can help return BP to normal after a slight drop such as standing up too rapidly.
Baroreceptors sense low BP and then medulla oblongata stimulated to start vasoconstriction (via SNS)
Differentiate local from systemic vasoconstriction by: 1) possible causes; 2) location; 3) effect on local tissue; and 4) effect on systemic BP.
Reduced blood flow to small area only in response to local stimuli (cold compress) elicit changes to pH, O2, and CO2 levels
Constriction all over the body; possible effects: increased blood pressure, reduced cell function (possible ischemia), possible cause of low blood volume
How does vasoconstriction in skin & viscera result in increased venous return?
Blood is moved to areas of low blood pressure (veins), moving blood towards the heart... increasing venous return
Predict 3 ways that cardiac function could be impaired.
Conduction system damage decreases efficiency
Muscle damage impairs pumping ability
Predict 3 ways that systemic circulation could be impaired.
General vasoconstriction or vasodilation
Common Heart Problems
Congenital heart defects
Hypertensive heart disease
Angina & heart attacks
Cardiac arrhythmias - not covered here
Congestive heart failure
Heart Problems: Diagnostic Tests for Cardiovascular Function
Useful in initial diagnosis & monitoring of dysrhythmias, myocardial infarction, atrial or ventricular hypertrophy, infection, pericarditis
Can monitor with portable Holter monitor.
Detection of valvular abnormalities or abnormal shunts of blood that cause murmurs; detected with stethoscope.
Used to record the heart valve & wall movements, blood flow, & CO.
Can also determine SV and see pericardium
Exercise stress tests (bicycle, step or treadmill)
To assess general cardiovascular function; can be used in fitness clubs & rehab programs following heart attacks or surgery.
An abnormal Echocardiogram.
"An abnormal Echocardiogram. Image shows a mid-muscular ventricular septal defect. The trace in the lower left shows the cardiac cycle and the red mark the time in the cardiac cycle that the image was captured. Colors are used to represent the velocity and direction of blood flow."
3- & 4-D Echocardiography
"GIF-animation showing a moving echocardiogram; a 3D-loop of a heart viewed from the apex, with the apical part of the ventricles removed and the mitral valve clearly visible. Due to missing data the leaflet of the tricuspid and aortic valve is not clearly visible, but the openings are. To the left are two standard two-dimensional views taken from the 3D dataset."
Chest x-ray films
Used to show shape & size of the heart - look for pulmonary congestion assoc. with heart failure
Patient presented with acute onset of dyspnoea. The frontal chest radiograph is key to diagnosis. It shows evidence of both interstitial & alveolar edema. Due in this case to pulmonary venous hypertension." Wiki Creative Commons
Computer Tomography studies (CT scan)
Used to diagnose CAD (coronary artery disease)
3D x-ray (shows more radio-dense things)
Dye is injected, mostly non-invasive
2-D: Rest & Exercise (Stress test)
Pictures taken before & after treadmill.
Extent of CAD
SPECT (3-D) Single Photon Emission CT
What is coronary steal syndrome?
A phenomenon when there are narrowed coronary ateries and a vasodilator is used
Which inadvertently acts to cause vasodilation elsewhere in the heart "stealing it" from ischemic zones
Visualization of blood flow in the coronary arteries.
Coronary angiography show stenosis (arrow) of left anterior descending coronary artery.
Measure pressure and assess valve & heart function
Determination of central venous pressure and pulmonary capillary wedge pressure
Color enhanced digital subtraction angiography scans of coronary arteries
This is a color-enhanced digital
(DSA) scan of a normal heart.
The major branches of the left
and right coronary arteries are
This is a color-enhanced DSA
scan of the heart of a person with
advanced CAD. Blood flow to the
ventricular myocardium is
Cardiac Catheterization - e.g. measure CVP
CVP = pressure near right atrium; reflects amount of blood returning to the heart
≈ right atrial pressure
CVP= Central venous pressure
-Reflects the amount of blood returning to the heart- Preload
Cardiac Catheterization - measure PCWP
"The pulmonary capillary wedge pressure or PCWP is the pressure measured by wedging a pulmonary catheter with an inflated balloon into a small pulmonary arterial branch" -> Good measure of Left Atrial Pressure
Coronary Catheterization & Angiography
"Visualization of the coronary arteries (in this case, the left coronary artery which gives the circumflex branch of left coronary artery)."
"Catheterization of a cardiac chamber, in this case the left ventricle (a ventriculogram)."
Cardiac catheterization cont.
Can also be used to inject thrombolytic agents or in laser therapy to break down clots, or balloon angioplasty to open coronary artery.
Injecting die right into the ventricle , look at the movement of the walls
This way you are exposing the whole body to thrombic .....?
Dopper studies (ultrasound)
Used to measure the direction & velocity of blood flow
TGs, Na+, K+, Ca++, electrolytes, Hb, hematocrit, WBC count
12. Arterial blood gas determination
Blood draw from radial artery
Determine: pH, pO2, pCO, H2CO3, lactate, Hb, COHb, OHb, electrolytes
--Iron reflects red light-that's why our blood is red
-measures the amount reflected back of the oxygenated and deoxygenated blood
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