Unit 4: ECG, Cardiac Cycle, Cardiac Output and Heart Rate & Unit 5: Blood Vessels, Blood Pressure, and Blood Pressure Regulation (Module 2)

electrocardiogram (ECG)

a recording of the electrical current spreading throughout the heart. The current can be detected by placing electrodes on the surface of the skin.

atrial depolarization

what is associated with the P wave?

ventricular depolarization and atrial repolarization

what is associated with the QRS complex

ventricular repolarization

what is associated with the T wave?

normal

a sinus rhythm is (normal/abnormal)?

enlarged atrium

an enlarged P wave can indicate…

MI

an enlarged Q wave can indicate…

enlarged ventricle

An enlarged R wave can indicate…

CAD

A flatter T wave can indicate…

hyperkalemia

an enlarged T wave can indicate…

cardiac cycle

systole and diastole of both the atria and ventricles

atrial systole

pushes blood into ventricles

end diastolic volume (EDV)

the amount of blood that has entered the ventricle at the end of atrial diastole; the maximum volume of blood contained within the ventricles prior to ventricular systole

ventricular systole

pushes blood through semilunar valves and into the body

atrial systole, ventricular systole, relaxation period

what are the 3 parts to the cardiac cycle?

isovolumetric contraction

when the ventricles contract without changing blood volume; blood volume within the heart remains the same until SL valves open

stroke volume

how much blood is ejected from the ventricle with each squeeze

end systolic volume

how much blood is left after ventricular systole

isovolumetric relaxation

all four valves are closed and blood volume within the ventricles remains the same; heart is relaxed

cardiac output

volume of blood ejected from the left ventricle each minute

CO = SR x HR

formula for cardiac output

preload, contractability, afterload

what are the three factors that determine SV?

preload

how much blood is in the heart before contraction; also known as EDV

Frank-Starling Law of the Heart

the greater the volume of blood within the ventricle, the greater the force of contraction; like a rubber band; excessive stretching of the heart wall will decrease the functionality of the contractile fibers (think mom hand diagram thing)

duration of ventricular diastole (HR) and venous return

what two things determine EDV?

venous return

amount of blood returning to the heart

contractility

strength of contraction at any given preload

positive inotropic agents

things that increase contractibility

calcium influx, digitalis (drug)

examples of positive inotropic agents

negative inotropic agents

things that decrease contractility

hyperkalemia (interferes with action potential), beta blockers (blocks NE receptors, slowing HR)

examples of negative inotropic agents

afterload

the pressure within the arteries that must be overcome in order for the SL valve to open (blood pressure)

decreases

if afterload increases, SV ______

congestive heart failure (CHF)

the failing of the heart to adequately pump blood

pulmonary edema

the failing of the left ventricle causes…

systemic edema

the failing of the right ventricle causes…

systemic edema

swollen feet, ankles, and abdomen could be symptoms of…

SA node, ANS, Endocrine system

what three things have control over heart rate?

Cardiovascular center (CVC)

in the medulla, effects heart rate

releases NE to increase the rate of depolarization of the SA and AV node; increases contractility by facilitation calcium entry

how do sympathetic nerve fibers (cardiac accelerator nerves) effect HR?

release ACh, decreasing depolarization of SA and AV node; little effect on contractility

how does the parasympathetic nerve fibers (vagus nerve) effect HR?

True

True or False: the CVC receives input from sensory receptors and higher brain centers

ionic imbalances, age, temperature, fitness

what are other things that influence HR?

decrease

hyperkalemia causes a _____ in HR

increase

hypercalcemia causes a ____ in HR

~120 BPM

average resting heart rate for infants

70-75 BPM

average resting heart rate for adults

decrease

hypothermia can cause a ___ in HR

lower

athletes will have a ___ resting HR compared to the average person

arrhythmia/dysrhythmia

conduction disturbance

AV block

arrhythmia where propagation of action potential is slowed

first degree

degree of AV block that has a prolonged P-R interval

second degree

degree of AV block that has missed beats; action potential is not reaching AV node (normal beats, just missed ones)

third degree

degree of AV block where the AV node receives no input from the SA node; the AV node paces itself at around 40 BPM

CAD or MI

some common causes of AV block

fibrillation

uncoordinated depolarization of the atria and ventricles

stroke risk

Afib makes a person a

little to no CO

what is the consequence of Vfib?

defibrillation

when an electrical current is applied to the heart to ‘reset’ conduction of the current

LV → arteries → arterioles → metarterioles → capillaries → venules → veins → RA

write out the systemic circuit with arrows

arteries

have a thick layer of smooth muscle (arteries vs veins)

vasoconstriction

in arteries, increased stimulation from the SNS will cause

vasodialation

in arteries, decreased stimulation from the SNS will cause

arteries

very elastic (arteries vs veins)

compliance

walls will expand with applied pressure without being damaged

arterioles

in this structure, smooth muscle in the wall of the vessel is important for regulating blood flow into capillaries; influences blood pressure

metarterioles

positioned in between the aarterioles and capillaries; very little smooth muscle

capillaries

where the gas exchange occurs; endothelium only one cell thick

precapillary sphincters

ring of smooth muscle right before capillary bed that opens and closes to regulate blood flow

venules

a collection of capillaries flowing into one another; carry blood toward the heart

veins

not as elastic (arteries vs veins)

veins

thinner walls (arteries vs veins)

veins

larger lumen (arteries vs veins)

veins

has valves (arteries vs veins)

veins

serves as a blood reservoir (arteries vs veins)

varicose veins

is the result of valves in the veins not functioning properly; blood flows backward and pools up in veins, causing them to leak into surrounding tissue

mechanical stress and age

what are the main causes of varicose veins?

venous return

the volume of blood returning to the right atrium

Blood pressure

venous return is largely determined by _____

central venous pressure

the pressure in the right atrium

0mmHg

how many mmHg is the central venous pressure?

LV continues to eject blood, skeletal muscle tissue pumping action, valves

how does blood return to the heart if BP in the veins is so low?

deep vein thrombosis (DVT)

when a thrombus forms in a deep vein, usually in the legs

blood pressure

hydrostatic pressure exerted by blood on the vessel walls.

False

True or False: pressure is lower in the arteries that first leave the heart

True

True or False: blood pressure gradually decreases as blood flows through the systemic circulation.

venae cava

where is blood pressure the lowest?

CO and vascular resistance

what is BP influenced by?

decreases

cardiac output decreases, blood pressure ____

increases

cardiac output increases, blood pressure ____

vascular resistance

opposition to blood flow

increase

increasing resistance leads to ___ in BP

decrease

decreasing resistance leads to a ____ in BP

vascular resistance

opposition to blood flow

Resistance increase, BP increase; resistance decrease, BP decrease

relationship between vascular resistance and BP

blood volume, blood viscosity, vessel diameter, vessel distensibility, vessel length

what are 5 things that vascular resistance depend on?

increases; increases

as blood volume increases, resistance ___ and BP ___

increases; increases

as blood viscosity increases, , resistance ___ and BP ___

increases; increases

if diameter of the blood vessel decreases, resistance ___ and BP ___

increases; increases

if vessel distensibility decreases, resistance ___ and BP ___