HSCI 335: Heart Physiology & Medicine: Exam 2

What is the clinical definition of atherosclerosis?

A chronic vascular disease of larger, muscular arteries involving plaque formation in the vessel wall

What is the alternative term for plaques formed during atherosclerosis?

atheromas

What three categories of development factors contribute to atherosclerosis?

genetic deposition, environmental exposure, and lifestyle habits

According to the atherosclerosis progression chart, what local complication can lead to rupture?

aneurysm

Which vessel type has the largest lumen diameter, reaching up to 30 mm?

vena cava

Which blood vessel type has a wall thickness of only 1 um?

capillary

How does the cross-sectional area of the capillaries compare to that of the aorta?

the total cross sectional area of the capillaries is significantly larger (approximately 1000 cm² vs 4cm²)

Which layer of the arterial wall contains the endothelium and internal elastic lamina?

tunica intima (interna)

What are the primary components of the tunica media?

smooth muscle, and the external elastic lamina

In which arterial wall layer is the vasovasaorum found in vessels with thick walls (> 0.5 mm)?

tunica adventitia (externa)

How are healthy endothelial cells oriented in relation to blood flow?

Their long axis is oriented parallel to the direction of blood flow

List 3 anti-clotting factors produced on the surface of normal endothelium?

heparin sulfate, thrombomodulin, and plasminogen activators

Which two vasodilators are secreted by healthy endothelium into circulation?

prostacyclin and nitric oxide

Under what flow condition are anti-inflammatory and antithrombogenic factors typically released by the endothelium?

laminar flow shear stress

How does activated endothelium change in terms of permeability?

permeability increases, allowing larger molecules to pass through the barrier

What type of molecules does injured and infected endothelium express on its surface to recruit leukocytes?

cell surface adhesion molecules

What is the consequence of a dysfunctional endothelium losing normal nitric oxide (NO) production?

loss of regulation for blood pressure, flow, smooth muscle contraction, and platelet activation

What type of blood vessels are primarily affected by the chronic vascular disease atherosclerosis?

larger, muscular arteries

What are 4 major clinical consequences of atherosclerosis?

ischemic heart disease, cerebral vascular disease, peripheral vascular disease, and local aneurysm/rupture

In which type of blood vessel is the mean blood velocity the lowest?

capillaries

Name the 3 primary layers of the arterial wall from innermost to outermost

tunica intima, tunica media, tunica adventitia

Which specific layer of the tunica intima provides a barrier regulating substance movement from blood to tissues?

endothelium

What is the structural component of the tunica intima located between the basement membrane and the tunica media?

internal elastic lamina

What is the name of the small vessels located in the tunica adventitia of the arteries with walls thicker than 0.5 mm?

vasa vasorum

Which anti-clotting factor is found specifically on the endothelial surface to activate plasminogen?

plasminogen activators

Normal endothelial cells primarily secrete which type of substances to regulate smooth muscle cells?

vasodilators

Under stressors, the endothelium can switch from producing anti-clotting factors to producing ___ factors

prothromiotic

What effect does turbulent blood flow have on the inflammatory state of the endothelium?

results in low, chronic inflammation

What do injured or infected endothelial cells express on their surface to recruit immune cells?

cell surface adhesion molecules

Which gas, normally regulating blood pressure and smooth muscle contraction, is lost during endothelial dysfunction?

nitric oxide (NO)

What is the result when overproduced Reactive Oxygen Species (O₂^-) react with nitric oxide?

it negates cardioprotection

List 3 substances synthesized by arterial smooth muscle cells for the extracellular matrix

collagen, elastin, and proteoglycans

In an activated state, smooth muscle cells migrate from the medial layer into the

tunica intima

Which 3 inflammatory mediators are produced by activated smooth muscle cells?

IL-1, IL-6, and TNF

Which cell type in the tunica adventitia can differentiate into myofibroblasts during atherosclerosis?

adventitial fibroblast

What is the initial step of atherosclerosis involving lipoproteins in the tunica intima?

lipoproteins accumulate and undergo oxidation

Which specific immune cells migrate into the intima and develop scavenger receptors to increase LDL uptake?

monocytes (which become marcophages)

The formation of ___ cells in the vessel wall leads to the production of superoxide

foam cells

What structural change may occur in later stages of an atherosclerotic plaque to harden it?

calcification

What process follows endothelial dysfunction and lipoprotein entry to form the earliest visible lesion of atherosclerosis ?

fatty streak formation

In plaque progression, smooth muscle cells secrete matrix to form a protective ___ over the lipid core

fibrous cap

What mechanical factor, combined with matrix breakdown, typically causes a fibrous cap to rupture?

hemodynamic stress

Which adhesion molecules are upregulated on the endothelium during monocyte recruitment ?

VCAM-1 and ICAM-1

A plaque that protrudes into the lumen but has a stable fibrous cap is categorized as an

stable atherosclerotic plaque

What event within an unstable plaque involves bleeding from small vessels inside the lesion?

intraplaque hemorrhage

During the “adaptation” stage of atherosclerosis, what does the vessel wall do to accommodate the growing plaque?

It undergoes remodeling to dilate the vessel wall

The “clinical” stage of atherosclerosis is characterized by plaque rupture and ___ of the lumen

occlusion

What is the aerodynamic diameter threshold for particulate matter categorized by ‘PM_2.5’?

< 2.5 um

What is the aerodynamic diameter threshold for ‘ultrafine’ particulate matter?

< 0.1 um

Through which biological mechanism does air pollution primarily trigger cardiovascular disease in the lungs?

oxidative stress and the release of inflammatory mediators

In the study of Kunzli et al, every 10 ug/m³ increase in PM_2.5 was associated with a 4.2% increase in what measurement ?

carotid intima-media thickness (CIMT)

Proximity to major roadways is associated with an increase in which atherosclerotic maker according to Hoffman et al.?

Coronary artery calcification

What diagnostic tool uses frequency analysis to detect ‘Dock’s murmer’ in coronary artery disease?

Cardiac auscultation (specifically coronary sonospectrographic anaylsis)

What is the primary source of external compression on coronary arteries?

the myocardium during systole

Which part of the heart wall experiences the highest external compression during the cardiac cycle?

endocardium

List the 3 primary determinants of myocardial oxygen demand

wall stress, heart rate, and contractibility

In myocardial auto regulation, ADP and AMP degrade into which potent vasodilator?

adenosine

List 4 metabolic factors that contribute to the auto regulation of coronary vasculature

adenosine, lactate, CO₂, and H⁺

What is the term for severe acute, transient ischemia where cardiac dysfunction persists long after flow is restored?

stunned myocardium

What is the term for chronic ventricular contraction dysfunction resulting from persistent, reduced blood flow?

hibernating myocardium

Is the damage associated with hibernating myocardium considered reversible?

Yes, function may improve with restoration of blood flow

Which ischemic syndrome is characterized by predictable, transient chest discomfort during exertion and emotional stress?

stable angina

How does a ‘fixed-threshold angina’ differ from ‘variable-threshold angina’?

fixed-threshold is related to a constant level of exertion, while variable-threshold involves a greater role of vasoconstriction

Which ischemic syndrome involves focal coronary artery spasms in the absence of atherosclerotic plaques?

variant (prinzmetal) angina

What defines ‘silent ischemia’?

ischemia occurring without perceptible discomfort or pain

What is the physiological cause of ‘microvascular angina’?

small vessels failing to dilate properly during increased demand, despite no significant atherosclerosis

Which biomarker level must be above the 99th percentile reference limit to define myocardial injury?

Cardiac troponin

Define ‘acute myocardial infarction' (MI)’ ?

acute myocardial injury with evidence of ischemia or coronary thrombosis

What is the cause of a Type 1 myocardial infarction?

athero/thrombotic occlusion due to plaque rupture or erosion

What is the cause of Type 2 myocardial infarction?

oxygen demand/supply mismatch unrelated to acute athero-thrombosis (ex, spasm, anemia, hypotension)

A pt. suffers cardiac death with ischemic symptoms before troponin levels could be measured. What type of MI is this?

Type 3 MI

What distinguishes Type 4b MI from Type 4c MI?

Type 4b is caused by silent thrombosis, while Type 4c is caused by in-stent restenosis

A myocardial infarction occurring within 48 hours of coronary artery bypass graft (CABG) surgery is classified as ___

Type 5 MI

Focal severe coronary atherosclerosis is typically defined by what percentage of narrowing in one or more arteries?

> 75 %

What heart condition is associated with ischemic myocardium exhibiting ectopic electrical activity and ventricular fibrillation?

sudden cardiac death

Ischemic heart disease can lead to chronic heart failure through a process called myocardial ___

remodeling

Who is credited with recording the first electrical activity from a frog heart in 1842?

Matteucci

In 1887, ___ recorded the first electrical activity from a human heart

Waller

Which scientist built the string galvanonmeter-based-3-lead EKG machine and won a Nobel Prize in 1924?

Einthoven

In what year did AHA standardize the 12-lead EKG as it is known today?

1954

According to the depolarization of cardiac muscle cells, a wave of depolarization moving toward a positive electrode results in what type of direction?

an upward (positive) deflection

A wave of depolarization moving away from a positive electrode results in a ___ deflection

downward (negative)

What occurs when a cardiac muscle cell is fully depolarized?

the voltmeter returns to the isoelectric baseline (zero potential)

How does the sequence of ventricular repolarization compare to the sequence of depolarization ?

it occurs in the opposite direction

Which cardiac cells depolarize first but repolarize last?

cells near the endocardium

List the order of action potential spread through the heart’s conduction system starting from the primary pacemaker

Sinoatrial node (SA) node → Atrial muscle → Atrioventricular node (AV) → His bundle → Purkinje fibers → Ventricular muscle

The P wave on the ECG represents

atrial depolarization (or conduction of impulse through the atria)

Where does the P wave normally appear relative to the QRS complex?

before the QRS complex

What clinical condition might be indicated if P waves are peaked, notched, or enlarged?

atrial hypertrophy

An inverted P wave may indicate reverse conduction through which structure?

the AV node

What does the QRS complex represent in the cardiac cycle?

ventricular depolarization (and conduction of impulse through ventricles)

The QRS complex is measured from the start of the __ wave to the end of the S wave

Q

The T wave represents the peak of ventricular recovery or the ___ period of repolarization

relative refractory

What morphology is typical for a normal T wave

round and smooth

What do tall, peaked, or tented T waves potentially indicate?

myocardial injury or electrolyte imbalance

The U wave is thought to represent the repolarization of the ___ system

His-Purkinje

Which wave is usually upright and rounded but may not appear on all ECGs?

The U wave

A prominent U wave may indicate toxicity from which medication?

digoxin

Name three electrolyte imbalances that may lead to a prominent U wave?

hypercalcemia, hypokalemia, and hypomagnesemia

What is the anatomical location for the V1 electrode?

4th intercostal space (ICS), 2 cm right of the sternum