Chapter 18 Heart Flashcards
Heart location
Medastinum, 2/3 left of the midsternal line
Heart Structure
Fist sized
Apex pointing inferiorly
Base pointing superiorly
Pericardium
Double walled sac enclosing the heart
Fibrous pericardium
Loose fitting superficial membrane of tough dense connective tissue
Serous pericardium
Thin slippery inner membrane. 2 layers: parietal layer and visceral layer
Parietal later of serous pericardium
Lines the internal layer of fibrous pericardium
Visceral layer of serous pericardium
Deeper layer, outer wall of heart
Pericardial cavity
Between the layers of serous pericardium. Contains serous fluid
Heart wall layers
Epicardium- visceral layer of Serous pericardium
Myocardium- Mostly cardiac muscle, bulk of heart wall
Endocardium- simple squamous epithelium
Right atrium
Receives blood from Vena Cava
Right ventricle
Pumps blood to pulmonary trunk
Pulmonary trunk
Blood to the lungs
Left atrium
Oxygen rich blood from pulmonary veins
Pulmonary veins
Relieve oxygen rich blood from lungs
Left ventricle
Pumps blood to aorta
Aorta
Delivers oxygen rich blood to body
Septum
Partition dividing the heart longitudinally
Auricles
Small wrinkled appendages increasing atrial volume
Atrioventricular grooves ( Coronary Sulcus)
Seperate atria and ventricles; coronary vessels
Interventricular sulci
Grooves on outer surface of inter ventricular septum
Pectinate muscles
Muscle bundles on the internal surface
Fossa Ovalis
Shallow depression in interstitial septum. Remnant of foremen ovale
Ligamentum arteriosum
Between pulmonary trunk and aorta
Trabeculae carneae
Irregular muscle ridges in ventricular chambers
Cordae tendinae
Collagen tendons anchoring the atrioventricular (AV) valve cusps to the papillary muscles
Papillary muscles
Cone like muscle fibers attached to inner ventricles
Atrioventricular valves (Blood From Atrium)
Tricuspid- Right valve, 3 cusps
Bicuspid(Mitral)- left valve, 2 cusps
Semilunar valves
Aortic SL valve- Left Ventricle
Pulmonary SL valve- Right ventricle
Pathway of blood
Pulmonary Circuit
Right ventricle pumps blood to pulmonary trunk, which carries it to lungs for gas exchange. Left Atrium receives oxygen rich blood from 4 pulmonary veins.
Pathway of Blood
Systemic circuit
Left ventricle pumps blood out the aorta to the body and heart. Aorta (thanks to branches) sends blood to body. Right atrium receives carbon dioxide blood from vena cava.
Thicken myocardium in what chamber?
Left ventricle bc of hardest work
Capillary beds
Gas exchange location in lungs
Coronary circulation
Arterial supply
From ascending aorta to coronary arteries:
Left CA to Anterior interventricular artery and circumflex artery.
Right CA to posterior interventricular artery and marginal artery
Middle cardiac vein
Posterior interventricular sulcus
Great cardiac vein
Anterior interventricular sulcus
Coronary sinus
Confluence of all coronary veins in the sulcus that dumps blood to right atrium
Angina pectoris
Pain in chest from lack of oxygen;
Weakened muscle not dead
Myocardial infarction
Heart attack; prolonged blockage of blood supply
Shape of cardiac muscle
Short fat and branching (interconnected)
Intercalculating disc
Junction btw branching cardiac cells that contain desmosomes and gap junctions
Desmosomes
Hold fiber cells together
Gap junctions
Allow action potential to conduct btw fibers
Because if interconnecting fibers and intercalculated discs, cardiac muscle functions as a..
Unit
Mitochondria is more numerous in
Cardiac muscle than skeletal
Cardiac Muscle Energy Source
Aerobic respiration
Mitochondria reflecting aerobic resp
Fuels: glucose, fatty acids,lactic acid
Action Potential of Myocardium contractile fibers
Depolarization
Plateau
Repolarization
Depolarization
- Autorhythenic cells stimulate. Fast sodium channels open, leading to rapid depolarization
- Slow calcium channels open, getting Ca++
- Sodium Channels close
Plateau
Slow calcium channels remain opened prolonging depolarizing
Repolarization
Calcium channels close, potassium channels remain open so potassium leaves
Myocardial Contraction Duration vs Skeletal
Much longer because of plateau of action potential (200msec vs 14-100)
Absolute refactory period
Greater than the contraction duration; prevents frequency wave summation and fatigue
Pacemaker potentials
Unstable resting potentials;
Constantly drift to threshold and AP
Fast opening calcium channels
Influx of calcium causes depolarization
No plateau
Repolarization Short
Calcium permeability decreases
Potassium increases
Sinoatrial Node
75 beats/min;
Pacemaker
Btw vena cava and right atrium
Atrioventricular node
40-60 Bpm
Inferior portion of interatrial septum
Atrioventricular bundle
Connection between atria and ventricles
Bundle branches
Right and left
Down interventricular septum to apex
Purkinje fibers
20-35 bpm
Spread superiorly into ventricular walls
Electrocardiogram
Recording of electrical activity in chest due to profiting AP in heart
P wave
Atrial depolarization
QRS Wave
Ventricular depolarization and atrial repolarization
T wave
Ventricular repolarization
P-Q interval
Atrial contraction occurs
S-T. Segment
Ventricular contraction
Arrhythmias
Irregular heart rhythm
Fibrillation
Rapid partial contractions
Need defibrillation to reset the pace
Cardiac cycle
- Atrial systole
- Ventricular systole
- Ventricular diastole
Atrial systole
Atrial contraction
Atrial blood > ventricle
Ventricular contraction
Isovolumetric contraction- AV valves close, builds pressure
Ventricular ejection- pressure makes SL valves open; blood out
Ventricular diastole (relaxing)
a. Lower pressure, all valves close
b. AV valves open, filling ventricles
Heart sounds
When valves close
AV Valve- Lubb
SL Valve- Dub
Incompetent valve
Valve doesn’t close all the way, makes heart work harder
Valvular Stenosis
Valve doesn’t open all the way, increased pressure
End Systolic Volume ESR
After systole, 50mL remaining
End diastolic volume
After filling, 120mL of blood in ventricle
Stroke volume
70mL
Cardiac output
Stroke volume X heart rate
