Cardiology: Cardiovascular Physiology (cdupa2022)

What are the two main functions of the heart?

1. transportation (oxygen and metabolites+ collect co2 and waste)

2. thermoregulation

How much blood does the heart pump out on average per minute?

5L/min

What is stroke volume? How much blood is an average stroke volume?

The volume of blood pumped by the left ventricle in a single heartbeat. 70 ml.

How do you calculate stroke volume?

Obtainable by subtracting ESV(end systolic volume) from EDV (end diastolic volume).

What is End Diastolic Volume?

The volume of blood in the right or left ventricle at the end of filling (diastole), before contraction (systole).

What is the average cardiac output?

about 5L/min

What is Ejection Fraction?

The proportion of EDV ejected from the ventricle

What is the average heart rate?

72 bpm

What 3 factors affect stroke volume?

1.) Myocardial contractility
2.) End Diastolic Volume (Cardiac Preload)
3.) Arterial Pressure (Cardiac Afterload)

What must cardiac output equal?

Venous return

Which factors manipulate the amount of venous return?

1.) Atrial Pressure changes
2.) Respiratory movement
3.) Skeletal muscle pump
4.) Increased venous tone

What is the purpose of heart valves?

To ensure the unidirectional flow of blood.

What are the "Inflow" valves, and what do they do?

The inflow valves are the tricuspid and mitral valves. They ensure the forward flow of blood from the atria into the ventricles.

What are the "Outflow" valves, and what do they do?

The outflow valves are the pulmonary and aortic valves. They ensure the forward flow of blood from the ventricles into the great vessels.

What are "valve defects"

Heart valves that become stenotic or insufficient/incompetent.

How do valve defects affect heart function?

They cause turbulent blood flow that causes abnormal heart sounds (murmurs)

Stenosis creates what type of overload

pressure overload

Incompetence creates what type of overload

volume overload

What is the function of the papillary muscles?

to anchor the atrioventricular heart valves to the walls of the ventricles.

What is the function of the Chordae Tendineae?

The Chordae Tendineae act as anchor ropes between the cusps of heart valves and the ventricles.

Mitral valves are _____ when the papillary muscles are contracted.

Closed

Mitral valves are ______when the papillary muscles are relaxed.

Open

What are the layers of the wall of the heart, from outermost to innermost?

Parietal pericardium (pericardial cavity, visceral pericardium) myocardium, endocardium

What fills the layers between the parietal and visceral layers of the pericardium (pericardial cavity)?

what secretes the pericardial fluid

Pericardial fluid

serous pericardium

Function of gap junction

allows rapid communication

Function of desmosomes

provides strength to hold fibers in place)

What electrolyte affects actin (thin filament) and myosin (thick filament) coupling

what is the electrolyte released by

calcium

sarcoplasmic reticulum

Which cardiac enzyme initiates the contraction coupling of actin in the thin filaments and myosin in the thick filaments in heart tissue?

Troponin

What is the function of Troponin T (TnT)?

The primary tropomyosin-binding subunit.

What is the function of Troponin I (TnI)?

Keeps the Troponin-Tropomyosin complex bound to the Myosin-binding sites on Actin.

What is the function of Troponin C (TnC)?

Binds calcium ions, causing conformational changes in TnI that pulls the Troponin-Tropomyosin complex away from the myosin binding sites on actin to make them available to the Myosin heads in the thick filaments.

What happened when calcium binds troponin?

causing conformational changes in TnI that pulls the Troponin-Tropomyosin complex away from the myosin binding sites on actin to make them available to the Myosin heads in the thick filaments.

What is resting membrane potential?

-70 (caused by 3Na-in:2K+out)

What is the multiphasic action potential steps?

1) Na+ gates open, Na+ rush in and depolarizes, when it closes, Ca+ gates open and slowly rush in to prolong depolarization, causing a plateau, ca+ gates close, and k- open, K leaves to repolarize

What effect does Hypokalemia have on resting membrane potential and the threshold for action potential?

Raises the RMP by making it more negative and raises the threshold for action potential.

What effect does Hyperkalemia have on resting membrane potential and the threshold for action potential?

Lowers the RMP by making it less negative and lowers the threshold for action potential.

How does Hypocalcemia affect the heart?

Shortens cardiac action potential, reduces the refractory period, increases heart rate, increases excitability of the myocardium, leads to cardiac arrhythmias.

How does Hypercalcemia affect the heart?

Prolongs cardiac action potential, increases the refractory period, decreases heart rate, reduces excitability of the myocardium, causes cardiac standstill in systole.

What is the pacemaker rate of the SA node?

60-100

What is the pacemaker rate of the AV node?

40-55

What is the pacemaker rate of the Bundle of His?

25-40

What is the pacemaker rate of the Bundle Branches?

25-40

What is the pacemaker rate of the Purkinje network?

25-40

What is an EKG?

Surface recording of the electrical activities of the heart on a moving graph paper

What does the P wave on EKG represent?

Atrial contraction

What does the QRS complex on EKG represent?

Ventricular contraction

What happens during ventricular systole?

Closure of the inflow valves, opening of the outflow valves, ventricular ejection

Which heart sounds are loud in mitral stenosis?

S1

Which heart sounds are soft in mitral regurgitation?

S1

What happens during ventricular diastole?

Closure of the outflow valves, opening of the inflow valves, ventricular filling, atrial kick

Which heart sounds are soft in aortic stenosis?

S2

Which heart sounds are loud in aortic regurgitation?

S2

Which patients can have an S3 heart sound?

Young adults, mitral regurgitation, CHF

Which patients can have an S4 heart sound?

Elderly, LVH, Hypertrophic cardiomyopathy

What is the pathophysiologic cause of audible splitting of S1?

Whenever the closure of the tricuspid valve is delayed.

Which conditions could cause detectable splitting of S1?

Right Bundle Branch Block and Left Ventricular Pacing

Which conditions could cause reverse splitting of S1?

Left Bundle Branch Block and Right Ventricular Pacing

Which conditions could cause normal detectable splitting of S2?

Increased RV filling and Reduced LV filling on inspiration

Which conditions could cause wide detectable splitting of S2?

Pulmonary Stenosis and Right Bundle Branch Block

Which conditions could cause fixed detectable splitting of S2?

Atrial Septal Defect

Which conditions could cause paradoxical splitting of S2?

Aortic Stenosis, Left Bundle Branch block, Right Ventricular Pacing, Hypertrophic Cardiomyopathy, Patent Ductus Arteriosus

What is Preload?

The volume of blood in the ventricles at the end of diastole (ventricular filling).

What is Afterload?

The resistance the ventricles must overcome to pump blood out.

Which factors affect preload?

Blood volume, venous tone and capacitance, and inflow valve incompetence

Which factors affect afterload?

Blood pressure, blood viscosity, and outflow valve stenosis

What is eccentric hypertrophy?

Physiologic cardiac remodeling in which sarcomeres are added in series in response to volume overload.

What is concentric hypertrophy?

Physiologic cardiac remodeling in which sarcomeres are added in parallel in response to response to pressure overload.

What causes pathologic cardiac injury?

Prolonged volume and pressure cardiac overload particularly with limited coronary blood supply.

Apoptosis of cardiomyocytes has what effect on the heart?

Loss of contractile force and thinning of ventricular walls

Replacement fibroblast growth stimulation has what effect on the heart?

Collagen synthesis and fibrosis as well as stiffening of the ventricular walls.

Which type of complications does concentric hypertrophy lead to?

Diastolic dysfunction and heart failure

Which type of complications does eccentric hypertrophy lead to?

Dilated cardiomyopathy and systolic heart failure

Right coronary artery disease can cause which area to infarct on MI?

Inferior MI

Left main coronary artery disease can cause which area to infarct on MI?

Anterolateral MI

Left anterior descending branch disease can cause which area to infarct on MI?

Anterior MI

Left circumflex branch disease can cause which area to infarct on MI?

Lateral MI

The tunica media is thicker in arteries or veins?

Arteries

Which type of capillary is comprised of an uninterrupted lining of cells held together by tight junctions with intercellular clefts for capillary exchange and where can you see this type in the body?

Continuous type, seen in the Blood Brain Barrier

Which type of capillary is comprised of a modified lining of cells with pores for the movement of fluid and small molecules across the capillaries?

Fenestrated type, seen in the Small Intestines

Which type of capillary is comprised of a modified lining of cells with large lumens for the movement of large cells and molecules across the capillaries?

Sinusoid type, seen in the Liver and Lymphoid tissues

What effect does the branching of arteries have on the surface area and pulsatility/velocity of blood flow through the microcirculatory units?

Increases surface area and decreases pulsatility/velocity of blood flow

What is the purpose of precapillary sphincters?

To open and allow blood flow through the capillaries

What is the purpose of capillaries?

To promote exchange of nutrients and metabolic end-products between the blood and the tissues.

What is the purpose of the lymphatic vessels?

To collect the interstitial fluid protein from the lymph capillaries.

What is the difference between pitting edema and peripheral edema?

Pitting edema is from increased formation of interstitial fluid (venous congestion and inflammation) whereas non-pitting edema is due to decreased removal of interstitial fluid due to lymphatic obstruction.

What are vasa vasorum?

The network of small blood vessels that supply the walls of large arteries and veins.

Why is the abdominal aortic wall thin and prone to the development of aneurysms?

Because vasa vasorum are absent below the origin of the renal arteries.

What happens to the thoracic aorta in the case of an obliterating endarteritis of the vasa vasorum?

It will weaken the aortic adventitia and lead to the formation of aneurysms.

What happens in the case of an aortic dissection?

A vasa vasorum ruptures and bleeds into the aortic wall, separating the tunica media from the tunica intima in the process.

What portion of blood in the body is held by the veins?

2/3

What portion of blood in the body is held by the arteries?

1/3

Which portion of the Medulla of the brain controls heart rate and force of contraction?

Cardioinhibitory center and cardiac-accelerator center

Which portion of the Medulla of the brain is able to send impulses ONLY to the SA and AV nodes via the vagus nerve?

The Cardio-inhibitory center

Which portion of the Medulla of the brain is able to send impulses to BOTH the SA and AV nodes as well as the myocardium via the sympathetic cardiac nerves?

The Cardio-accelerator center

Which portion of the Medulla of the brain controls the amount of tension in the vascular smooth muscle?

The Vasomotor Center

What effect does Natriuretic Peptide have on the body?

Increases Na+ and volume loss in urine, reduces thirst, blocks ADH, aldosterone, epinephrine, and norepinephrine release.

Which leads on EKG depict the circumflex artery?

I, aVL, V5, V6

Which leads on EKG depict the right coronary artery?

II, III, aVF

Which leads on EKG depict the left anterior descending artery?

V1, V2