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BIO202-CH18-Heart
BIO202 - Ch 18 - Heart - Marieb/Hoehn - RioSalado - AZ
| Question | Answer |
|---|---|
| The heart weighs __. | 250 - 350 g - less than a pound. |
| Where is the heart found? | Mediastinum - medial cavity of thorax |
| Heart location in relation to bones? | Heart extends obliquely 12-14 cm (5 inches) from 2nd rib to 5th intercostal space - in mediastinum rest on diaphragm |
| 2/3 mass of heart __. | lies to left of midsternal line. |
| The base of heart points to __ & apex points __. | shoulder (R), left hip |
| Endocardium is comprised of? | Glistening white sheet of endothelium (squamous) resting on thin CT layer - lines heart chambers. |
| The __ is continuous w/the endothelial lining of the blood vessels leaving & entering the heart. | Endocardium - located on inner myocardial surface. |
| Which chamber forms the heart apex? | L-ventricle |
| The muscle bundles on the right atrium anterior. | Pectinate muscles - becuase they look like teeth of a comb. |
| The __ is the spot that marks where opening was in the fetal heart. | Fossa ovalis |
| myocardium | Cardiac muscle tissue |
| pericardium | Tough fibrous sac that surrounds, protects & lubricates the heart. |
| endocardium | Smooth lining in heart's chambers composed of CT & layer of epithelial cells. |
| endothelium | Epithelial cell layer of heart & blood vessels. |
| Septum | Thick wall that divides R & L halves |
| Atrium | Top two heart chambers |
| Ventricle | Bottom two heart chambers |
| Hearth has __ halves & __ chambers. | 2 - 4 |
| Atrioventricular Valve | Flaps of membrane separating an atrium & ventricle chamber (R=tri & L=Bi or mitral). |
| Atria are __ for blood returning to heart & contribute __ to the propulsive pumping activity of heart. | Receiving chambers - little |
| Blood enters R atrium via what 3 veins? | Superior vena cava, inferior vena cava, & coronary sinus. |
| What veins enter the L atrium? | The 4 pulmonary veins |
| The __ ventricle forms most of anterior & the __ the posterioinferior. | Right, left |
| The R ventricle pumps blood into the __ while the L ventricle ejects blood into the __. | Pulmonary trunk, aorta |
| The blood vessels that carry blood to/from the lungs form __. | The pulmonary circuit - serves gas exchange |
| The blood vessels that carry functional blood supply to/from tissues __. | The systemic circuit |
| The right side of the heart is the __ circuit pump. | Pulmonary |
| The left side of the heart is the __ circuit pump. | Systemic |
| Path of blood through heart. | RA -> RV -> Lungs -> PV -> LA -> LV -> Aorta |
| The pulmonary circuit served by __ ventricle is a __ pressure circulation. | right - low |
| The systemic circuit served by __ ventricle is a __ pressure circulation. | left - high - that's why left ventricle is bigger. |
| What is the shortest circulation in the body? | The coronary circulation - blood supply to heart. |
| What are anastomoses? | Where blood vessels merge. |
| "Heart strings" / chordae tendineae | Tough, collagen-reinforced strands that connect AV valve flaps to cone-shaped muscles that extend out of ventricle wall. |
| Semilunar valves (aortic & pulmonary) | Valves between the ventricle & arteries leading away from it. During a heartbeat, this valve opens & closes to keep blood moving in one direction. 3 cusps |
| Coronary circulation | Heart's own blood supply. Coronary arteries |
| Coronary arteries | Bring blood to the heart for itself. |
| Aorta | The major artery carrying oxygenated blood away from heart. |
| During a MI, damage to the __ ventricle is most serious. | Left, because it is the systemic pump & cannot handle being replaced by scar tissue. |
| Atrioventricular valves prevent __. | backflow into atria when ventricles contract. |
| The R-AV valve is the __. | Tricuspid - has 3 flexible cusps. |
| The L-AV valve is the __. | MItral - 2 cusps |
| What occurs in valvular stenosis? | Valve flaps become stiff (scar tissue or Ca salt deposit) & constrict opening. |
| "lub" | AV valves are closing as the 2 ventricles contract. Beginning of ventricular systole. |
| "dup" | The semilunar valves are closing as ventricles relax. |
| Superior vena cava | Blood from head, arms & chest arrives to heart through this. |
| Inferior vena cava | Blood from lower body returns to heart through this. |
| What is functional syncytium? | Cardiac cells that are electrically coupled in the myocardium that behave like single coordinated unit. |
| What give cardiac cells a high resistance to fatigue? | Large mitrochondria - 25-35% of volume |
| Cardiac muscles lack __. | triads |
| Each cardiac muscle must be stimulated to __, but some initiate their own depolarization, which is called __. | contract by a nerve cell - automaticity or autorhythmicity |
| The long cardiac refractory period prevents __. | tetanic contractions, which would stop heart pumping action. |
| The plateau of heart cell contraction helps how? | Provides sustained contraction needed to eject blood from heart. |
| Cardiac muscle has more __ than skeletal. | mitochondria - needs more oxygen |
| Cardiac muscle is __ & doesn't depend on NS. | intrinsic - NS can alter basic rhythm |
| Autorhythmic cells don't maintain __. | a stable resting potential |
| intercalcalted discs | Junctions that span heart muscle cell's plasma membrane where 2 cells abutt - connected by desmosomes & gap junctions |
| Cardiac conduction system | Pacemaker cells in the heart that spontaneously generate & conduct electrical impulses - noncontractile cells. |
| Sinoatrial node (SA) | Cluster of cells in upper wall of R atrim - generate waves about 75X/min that spread swiftly over both. |
| Atrioventricular note (AV) | Signal from SA node arrives & a .1s delay occurs before signal given to fire ventricles to contract - Located at interior portion of interatrial septum. |
| Pacemaker potential is due to __. | The special properties of ion channels in sarcolemma - causes influx of calcium that reverses membrane potential. |
| Sequence of excitation of heart. | SA->AV->AV Bundle -> R/L bundle branches -> Purkinje |
| The bulk of bentricular depolarization depends on __. | Purkinje fibers that supply signal to cell-to-cell transmission via gap junctions. |
| Ventricular contraction begins at __ & moves toward? | Heart apex -> atria |
| A defective SA node can have what consequences? | Etopic focus (abnormal pacemaker) where AV node takes over & extrasystole - premature ventricular contraction - PVC's |
| Damage to AV node or __ interferes with ability of ventricles to receive pacing impulses. | heartblock |
| What is the "bundle of His"? | Atrioventricular bundle - electrical connection between the atria & ventricles. |
| The cardiac centers are located __. | in the medulla oblongata |
| P wave on ECG results from? | Movement of depolarization wave from SA node through atria - then atria contract. |
| Blood pressure | The fluid pressure blood exerts against vessel walls. Highest in aorta - measured in mm of mercury (Hg). |
| Systolic pressure | Peak of pressure in aorta while (L) ventricle contracts & pushes blood into the aorta. |
| Diastolic pressure | Lowest blood pressure in aorta when blood is flowing out of it & heart is relaxed. |
| The QRS complex of ECG results from? | Ventricular depolarization & precees ventricular contractions. |
| The T wave of ECG caused by? | Ventricular repolarization |
| During S-T segment of ECG is the __ phase. | plateau |
| Cardiac Output (CO) | Amount of blood pumped out by each ventricle in 1 minute - HR X SV = about 5.25 L /min - little more than 1 gallon |
| Stroke Volume | Volume of blood pumped out by 1 ventricle with each beat. |
| Cardiac reserve for nonathletic people is __ times resting volume, while trained athletes can reach __. | 4-5X, 7 |
| SV or stroke volume represents the difference between __ & __. | EDV (end diastolic volume) & ESV (end systolic volume) |
| What is EDV? | End diastolic volvume - the amount of blood that collects in a ventricle during diastole. |
| What is ESV? | The volume of bood remaining in a ventricle after it has contracted - end systolic volume. |
| SV = ? | SV = EDV - ESV |
| Where & what is the point of maximal intenisity (PMI)? | Spot between 5th & 6th ribs where apex contracts the chest wall. |
| External sac (not direct covering) of heart is the __ whose superficial part is the __. | pericardium, fibrous pericardium - dense CT that (1) protects heart, (2) anchors it, (3) prevents overflowing. |
| Deep to fibrous pericardium is __. | Serous pericardium - 2 layer serous membrane |
| 2 layers of serous pericardium is __. | Parietal & visceral (epicardium). |
| Where is the pericardial cavity? | Between parietal & visceral layers - contains serous fluid. |
| Pericarditis is characterized by __. | Pain deep to sternum, creaking sound w/stethoscope. |
| What is cardiac tamponade? | "Heart plug" - excess fluid in pericardial cavity that compresses heart. |
| 3 layers of heart wall. | Epicardium, myocardium, & endocardium |
| Which heart layer is often infiltrated with fat? | Epicardium |
| Which heart layer is composed of cardiac muscle? | Myocardium - the layer that contracts |
| Fibrous skeleton of heart is composed of? | Dense network of CT that reinforces myocardium - collagen & elastin |
| Describe the Frank-Starling law of the heart | The critical factor controlling stroke volume is the preload |
| Preload is? | The degree to which cardiac muscle cells are stretched just before they contract. |
| Resting cardiac cells are normally __ than optimal length. | Shorter |
| The most important factor stretching cardiac muscle is __. | venus return - amount of blood returning to heart. |
| What types of activities increase EDV? Decrease? | Slow heart rate or exercise - blood loss or rapid heart beat |
| Major intrinsic factor influencing SV is? | EDV |
| What intrinsic factor influencing SV is? | EDV (end diastolic volume) |
| What extrinsic factor influences SV? | Increase heart muscle contractility. |
| The contractile strength achieved at a given muscle length. | Contractility |
| An increase in heart cell contractility is due to __. | greater Ca2+ influx into cytoplasm from extracellular fluid & SR. |
| Greater SV means what? | Ejection of more blood from the heart. |
| Contractility is influenced/enhanced by? | Ca2+, glucagon, thyroxine, epinephrine, and the drug digitalis. |
| Negative inotropic agents include? | Acidosis (excessive H+), rising intracellular K+ levels, & calcium channel blockers. All decrease heart conractility. |
| Afterload is? | The pressure that must be overcome for the ventricles to eject blood - back pressure exerted by arterial blood. |
| HR is? | Heart rate |
| What are positive chronotropic factors? | Factors that increase HR |
| The most important extrinsic controls affecting HR. | Autonomic NS |
| SNS releases __ that causes pacemaker cells to fire more rapidly. | NE - Norepinephrine |
| When heart beats faster, there is less tme for __ filling & so a lower __. | Ventricular - EDV |
| Parasympathetic activity has __ effect on cardiac contractility. | little or no |
| Cutting the vagal nerves to heart would do what? | Increase heart rate 25 beats/min due to inherent rate (100 b/m) of pacemaking SA node. |
| Atrial (Bainbridge) reflex | Sympathetic reflex initiated by increased venus return & increased atrial filling - stretching atrial walls increase HR by stim. SA node & atrial stretch receptors. |
| What chemicals influence heart rate? | Hormones, ions - age, gender, exercise, body temp |
| Thyroxine in chronic hyperthyroid individuals __. | May develop a weakened heart due to a slower but more sustained increase in HR. |
| Hypocalcemia __ the heart & hypercalcemia __. | depress - prolong the plateau phase of action potential. |
| What is hyperkalemia & how does it affect the heart. | Excessive K+ may lead to heartblock & cardiac arrest |
| What affect does hypokalemia have on heart? | Lack of K+ heart beats feebly and arrhythmically. |
| Tachycardia results from? | Fast HR (100+ beats/min) - body temp, stress, drugs, or heart disease - promotes fibrillation. |
| Bradycardia results from? Danger is? | Inadequate blood circulation to tissues & a warning of brain edema after head trauma. |
| What is CHF - congestive heart failure? | When CO of heart is so low blood circulation is inadequate to meet tissue needs - weakened myocardium. |
| Dilated cardiomyopathy (DCM) | Ventricles stretch & become flabby & myocardium deteroriates - increased levels of Ca2+ to adapt & heart enlargement. |
| If left side of heart fails it is __. | Pulmonary congestion |
| If right side of heart fails it is __. | peripheral congestion - blood stagnates in body organs - edema |
| The heart is derrived from __. | Mesoderm |
| Foramen ovale is? | Foramen in fetal heart that connects the 2 atria & allows blood entering the right heart to bypass the pulmonary circuit. |
| Ductus arteriosus is? | Another bypass of pulmonary trunk & atria in fetalis |
| Stress of blood flow is greatest where? | Mitral valve |
| 2 classes of BP-lowering drugs. | Beta-blockers & ACE inhibitors. |
Created by:
Ladystorm