Cardiovascular System Pt.1 Flashcards by Julia Jupille

What is the main function of the CV system

Transport of nutrients, water, gases, wastes, immune cells, and hormones

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What are the 2 main circulatory paths

Pulmonary (heart-lungs-heart, deoxygenated to oxygenated) and systemic (heart-body/brain-heart, oxygenated to deoxygenated)

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Where do arteries and veins move blood

Arteries move it away from the heart, veins carry blood towards the heart

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What is blood composed of

Plasma (water, ions, amino acids, proteins, lipids, gases), and cellular components

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What are the cellular components of blood

Erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (cell fragments)

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What is another word for cardiac muscle

Myocardium

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What are cardiac muscle cells called

Cardiomyocytes (autorhythmic and contractile)

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Where does the signal to contract in the heart originate

The sinoatrial (SA) node

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How are cardiocytes connected

Electrically via gap junctions in intercalated disks and physically via desmosomes (keep cells from pulling apart)

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What percent of myocytes are contractile

99%

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What is the pacemaker potential in authorhythmic cells

I(f) channels open at -60 mV, permeable to potassium and sodium but net Na influx allows slow depolarization (slope determines HR)

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What is the AP due to in voltage-gated Ca and K channels

Ca++ is what really depolarizes the cell

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What are the 3 unique characteristics of contractile cell APs

2 types of K channels, voltage-gated Ca channels, and much longer duration/refractory period to prevent summation of twitches (so blood can pump properly)

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What are the steps of contractile cell APs

Resting membrane potential about -90: 1) Na channels open, 2) Na channels close and fast K channels open, 3) Ca channels open, fast K close, some slow K open (causes plateau), 4) Ca channels close and more slow K channels open

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How does the electrical signal get from the atria to the ventricles

From SA node via internodal pathways to atrioventricular (AV) node

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What is the ventricular conducting system

AV bundle/bundle of His goes to bundle branches and then to Purkinje fibers (apex to base)

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How is an electrocardiogram taken

Einthoven’s triangle

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What is an electrocardiogam

Summed electrical activity of all heart cells

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What are waves of ECGs

Deflections above or below the baseline (P,Q,R,S,T)

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What are segments of ECGs

Sections between two waves (P-R, S-T, etc)

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What are intervals of ECGs

Combinations of waves and segments (PR, QT)

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What does the P wave correspond with

Atrial depolarization (tells atria to contract/systole)

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What does the P-R segment correspond with

Conduction through the AV node and bundle

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What does the QRS complex correspond with

Ventricular depolarization (tells ventricles to contract/systole)

What does the T wave correspond with

Ventricular repolarization (tells ventricles to relax/diastole)

When does atrial repolarization happen on an ECG

Not visible but during QRS complex

What is bradycardia

Slower than normal HR

What is tachycardia

Faster than normal HR

What is a heart arrhythmia

Skipped or dropped beats, extra beats (premature ventricular contractions), and fibrillation (loss of coordinated electrical signaling and unorganized contraction)

What is ischemia

Heart condition that leads to tissue damage as the result of lack of blood and oxygen flow

What is a conduction block

Affects electrical signal conduction (slower than usual or not able to get through necessary tissues)

What increases pressure in the heart

Contraction/systole

What are the events of the cardiac cycle

1) Late diastole, 2) Atrial systole, 3) Isovolumic ventricular contraction, 4) Ventricular ejection, 5) Isovolumic ventricular relaxation

What happens during late diastole in the heart

Both atria and ventricles are relaxed, blood fills the atria and ventricles via gravity (AV valves open)

What happens during atrial systole

Last bit of blood is pushed into ventricles so they are filled with their EDV (end diastolic volume)

What happens during early (isovolumic) ventricular contraction

Ventricular pressure rises, AV valves close, causing "lub" S1 sound

What happens during ventricular ejection

Ventricles contract, pressure increases, SL valves open and blood is pushed into arteries, ESV (end systolic volume) left in ventricles

What happens in ventricular relaxation

Ventricular pressure decreases, closing semilunar valves, and causing the "dup" S2 valve

When do AV valves close

When pressure in the ventricles is greater than in the atria

When do SL valves open

When ventricular pressure is greater than aortic pressure

What is the dicrotic notch

Increased aortic pressure caused by backward suction from SL valves closing

What is the equation for cardiac output

Stroke volume times HR

What is cardiac output (CO)

Volume of blood pumped out by one ventricle (usually left) per minute

What is stroke volume

Volume (mL) of blood pumped by a ventricle per contraction (EDV-ESV)

What is heart rate

Number of heart beats per minute (bpm)

How can the vagus nerve alter heart rate

Vagus nerve activates parasympathetic neurons, increasing K efflux and decreasing Ca influx, hyper polarizing cell, decreasing HR

How does the sympathetic nervous system and adrenal medulla affect heart rate

SNS and adrenal medulla activate sympathetic neurons, release NE onto B-1 receptors of autorhythmic cells, increasing Na and Ca influx, increasing rate of depolarization, increasing HR

What is stroke volume determined by

Force of contraction in ventricular myocardium

What is the force of contraction in ventricular myocardium influenced by (for stroke volume)

Contractility and muscle fiber length at beginning of contraction (EDV)

What is contractility

Forcefulness of contraction of individual ventricular muscle fibers (Ca interaction with troponin)

What effect does sympathetic innervation have on contractility

Increases force of contraction in contractile cells due to Ca increase

What does NE and E bind to in contractile cells

B-1 receptors

What happens once B-1 receptors are bound to

cAMP 2nd messenger system is activated, phosphorylating voltage-gated Ca channels (increasing time they're open) or phospholamban (increasing CA ATP-ase on SR and storing more CA in the SR)

What is the Frank-Starling law

Stroke volume increases as EDV increases because of preload (degree of stretch)

What is venous return

Amount of blood entering the heart through veins (influenced by skeletal muscle pump, respiratory pump, and venoconstriction)

What is the skeletal muscle pump

As muscles contract, they compress veins and force blood back to the heart (valves prevent back flow)

What is the respiratory pump

When the chest cavity decreases in volume, blood gets pushed into the heart

What pathway is activated by B-1 receptors to cause venous constriction

PLC-IP3 pathway