HeartHeartCirculation & Circulation & PhysiologyPhysiology

Ch. 18Ch. 18

Blood PathwayBlood PathwayPulmonary circulationPulmonary circulation – to – to

and from lungs (right side of and from lungs (right side of heart)heart)

Systemic circulationSystemic circulation – to and – to and from body (left side)from body (left side)–RenalRenal – to and from kidneys – to and from kidneys–Hepatic portalHepatic portal – to and from – to and from liverliver

–CoronaryCoronary – to and from – to and from heart muscleheart muscle

Heart ValvesHeart ValvesDirect blood flow in one Direct blood flow in one directiondirection

AV (atrio-ventricular) valvesAV (atrio-ventricular) valves – supported by chordae – supported by chordae tendonae; open when atria tendonae; open when atria contractcontract–Right AV – “Right AV – “tricuspidtricuspid” valve” valve–Left AV – “Left AV – “bicuspidbicuspid” or ” or “mitral” valve “mitral” valve

Semi-lunar valvesSemi-lunar valves – open – open when ventricles contractwhen ventricles contract–Aortic valveAortic valve – between – between left ventricle and aortaleft ventricle and aorta

–Pulmonary valvePulmonary valve – – between right ventricle between right ventricle and pulmonary trunkand pulmonary trunk

–Problems when valves Problems when valves ““prolapseprolapse” or suffer ” or suffer from “from “stenosisstenosis” ” (scarring); can happen (scarring); can happen due to genetic defects, due to genetic defects, strep infections, or strep infections, or heart diseaseheart disease

Coronary CirculationCoronary CirculationMyocadium too thick for Myocadium too thick for diffusion of blood from diffusion of blood from heart chambers to be heart chambers to be effectiveeffective

Coronary arteries supply Coronary arteries supply blood to heart muscle.blood to heart muscle.

Arteries branch from Arteries branch from base of aorta and base of aorta and form a “crown” form a “crown” around the heartaround the heart

Cardiac veins collect Cardiac veins collect and return blood to and return blood to circulationcirculation

Problems happen Problems happen when blockages occurwhen blockages occur–Angina pectorisAngina pectoris – – “chest pain”“chest pain”

–Myocardial infarctionMyocardial infarction – “cardiac muscle – “cardiac muscle death”, “coronary”, death”, “coronary”, “heart attack”“heart attack”

Heart PhysiologyHeart PhysiologyNodal System – intrinsic Nodal System – intrinsic systemsystem–SA NodeSA Node – sinus rhythm – sinus rhythm–AV NodeAV Node – nodal rhythm – nodal rhythm (.04 secs)(.04 secs)

CircuitCircuit–Starts with SA node ----Starts with SA node ----AV node ------ AV AV node ------ AV Bundle (Bundle of His)Bundle (Bundle of His)

–Bundle branches Bundle branches (Purkinje fibers)(Purkinje fibers)

–Contraction from Contraction from apex upwardsapex upwards

–Entire process Entire process takes .22 secstakes .22 secs

–Rate controlled by Rate controlled by sympathetic and sympathetic and parasympatheticparasympathetic

ProblemsProblems–ArrythmiasArrythmias – irregular – irregular rhythmrhythm

–FibrillationFibrillation – ineffective – ineffective ventricular contractionventricular contraction

–Ectopic focusEctopic focus – – development of new development of new pacemaker which pacemaker which interferes with normal interferes with normal pacemakerpacemaker

–ExtrasystoleExtrasystole – – premature contractionpremature contraction

–Heart blockHeart block – no AV – no AV node; requires node; requires artificial pacemaker (2 artificial pacemaker (2 kinds: fixed rate and kinds: fixed rate and on-demand)on-demand)

Cardiac CycleCardiac CycleAll events associated with All events associated with blood flow through heart blood flow through heart during one heart beatduring one heart beat

SystoleSystole – contraction of – contraction of ventriclesventricles

DiastoleDiastole – relaxation of – relaxation of ventriclesventricles

At 75 bpm average cycle is At 75 bpm average cycle is 0.8 secs0.8 secs

Heart soundsHeart sounds–““lublub” – AV valve closes, ” – AV valve closes, louder, longer and more louder, longer and more resonantresonant

–““dubdub” – SL valve snaps ” – SL valve snaps shut, short, sharpshut, short, sharp

Left side usually closes Left side usually closes before right side, so sounds before right side, so sounds of individual valves can be of individual valves can be distinguisheddistinguished

MurmursMurmurs – abnormal or – abnormal or unusual sounds; occurs unusual sounds; occurs when normally smooth when normally smooth blood flow strikes blood flow strikes obstructions or flows in obstructions or flows in the wrong direction, the wrong direction, flow is turbulent and flow is turbulent and generates sounds.generates sounds.

Electrocardiogram (EKG)Electrocardiogram (EKG)Measurement of Measurement of electrical output of the electrical output of the heart’s electrical systemheart’s electrical system

Consists of 3 types of Consists of 3 types of “deflection waves”:“deflection waves”:–P waveP wave – impulse from – impulse from SA nodeSA node

–QRS waveQRS wave – – depolarization of depolarization of ventricles (unequal in ventricles (unequal in size due to size size due to size differences of differences of ventricles)ventricles)

–T waveT wave – – repolarization of repolarization of ventriclesventricles

P-R = beginning of atrial P-R = beginning of atrial excitationexcitation

Q-T = beginning of Q-T = beginning of ventricle contractionventricle contraction

Regulation of RateRegulation of RateNervous Control Nervous Control

–Sympathetic releases Sympathetic releases norepinephrine to stimulate norepinephrine to stimulate SA and AV nodes; stress SA and AV nodes; stress (emotional or physical)(emotional or physical)

–Parasympathetic (via vagus Parasympathetic (via vagus nerves) releases ACh to nerves) releases ACh to slow things downslow things down

Chemical controlChemical control–HormonesHormones

EpinephrineEpinephrineThyroxineThyroxine

atrial natriuretic factor atrial natriuretic factor ((ANFANF) - causes ) - causes vasodilation and vasodilation and kidneys to dump water; kidneys to dump water; lowers blood pressurelowers blood pressure

Antidiuretic hormone Antidiuretic hormone ((ADHADH) – vasoconstriction ) – vasoconstriction and tells kidneys to hold and tells kidneys to hold water; alcohol interfers water; alcohol interfers with this with this

Physical factorsPhysical factors–AgeAge–GenderGender–ExerciseExercise–Body temperatureBody temperature–Fetal rate – 2x adultFetal rate – 2x adult

PathologyPathologyTachycardiaTachycardia – rapid heart rate – rapid heart rateBradycardiaBradycardia – slow heart rate – slow heart rateCongestive heart failureCongestive heart failure – –

ventricles don’t pump ventricles don’t pump effectively, circulation is effectively, circulation is inadequateinadequate–Pulmonary congestion – left Pulmonary congestion – left side failsside fails

–Systemic congestion – right Systemic congestion – right sideside failsfails

HypotensionHypotensionHypertensionHypertension (silent (silent killer); stresses killer); stresses myocardium which myocardium which enlarges heart, vessels enlarges heart, vessels tear which increases tear which increases platelet deposition and platelet deposition and Ca+ depositsCa+ deposits

Any Questions?Any Questions?