Applied Physio lecture 27, 28 and 29 (exam 3)

These flashcards cover key terms and definitions related to ECG, cardiac contractility, and related physiological concepts.

Atrial Depolarization

Represented by the P wave in an ECG.

PR segment

Represents the AV nodal delay, allowing for atrial contraction.

QRS complex

Represents sequential depolarization of the ventricles.

T wave

Indicates repolarization of the ventricles.

Asystole

Absence of electrical activity in the heart.

Excitation-Contraction Coupling

The process by which electrical excitation leads to muscle contraction. Calcium activates the contractile proteins , allowing cross-bridge cycling between actin and myosin filaments for contraction. Calcium induced Ca2+ release (CICR)

Cardiac Output

The volume of blood pumped by the heart per minute.

CO = SV (stroke volume) x HR (heart rate)

Pulse Pressure

The difference between systolic and diastolic pressure.

Afterload

pressure in arteries. pressure against which the heart pushes. increased afterload causes more energy for left ventricle to open aortic valve. increasing afterload decreases SV

Preload

pressure at which the heart fills. SV effected by degree of stretch of the ventricles It is the initial stretching of the cardiac muscle fibers at the end of diastole, directly related to ventricular filling. increasing preload increase SV

Skeletal Muscle vs cardiomyocytes

Skeletal muscle fibers are long, cylindrical, and multinucleated cells responsible for voluntary movements and have short action potentials, while cardiomyocytes are branched, striated cells with a single nucleus that function involuntarily to pump blood with long action potentials

Stenosis

Narrowing of a blood vessel or valve.

Frank-starling law of the heart

increasing right atrial pressure increases SV of both ventricles

Pressure volume curves

Area of the PV loop is the work done by the heart, length across is stroke volume. bounded by passive and active tensive curves

Contractility

ability to produce force at any stretch. can be altered by changing the amount of calcium releasing and the myofilament sensitivity to calcium. increasing contractility increases SV

Average Velocity equation

V - Qv (flow)/ A (cross sectional area)

Compliance with elasticity

High compliance means it can fit more volume per change in pressure, stretch easily. Low compliance means it can fit less volume per change in pressure, stiff. Depends on the makeup of the vessel. Drives blood flow

BP equation

systolic pressure/diastolic pressure

Pulse pressure equation

systolic - diastolic pressure

Mean arterial pressure (Pa) equation

P diastolic + (systolic - diastolic pressure)/3

or

CO x TPR

Blood vessels

they branch, reducing their diameter but increasing their overall area allowing for efficient delivery of blood to the cells throughout the body

Flux equation

Js = P (permeability) x change in concentration

Flow equation

Qs = A (area) x P (permeability) x change in concentration

Flow = flux/Area

driving force is the concentration difference

How to increase capillary solute diffusional transfer

1. increase blood flow (Qv)

2. Increase the effective area for diffusion (S)

3. increase the gradient for diffusion (Ca (arterial concentration)-Ci (interstitial fluid concentration)