Systemic circulation
Left side of heart
Pulmonary circulation
Right side of the heart
Functions of the heart
Generating BP
Routing blood
One way blood flow
Regulating blood supply
Pericardium
Double-layered closed sac that surrounds the heart
Pericarditis
Inflammation of serous pericardium
Cardiac tamponade
Large volume of fluid or blood accumulates in pericardial cavity and compresses the heart from the outside
Fibrous pericardium
Tough, fibrous connective tissue outer layer
Serous pericardium
Thin, transparent inner layer
Function of fibrous pericardium
Prevents overdistension of heart and anchors it within mediastinum.
Parietal pericardium
Serous pericardium lining fibrous pericardium
Visceral pericardium
Serous lining that covering surface of heart
Pericardial cavity
Space between visceral and pericardia, filled with pericardial fluid
Function of pericardial fluid
Reduce friction as heart moves in pericardial sac
3 layers of heart wall
Epicardium, myocardium, endocardium
Epicardium
Thin serous membrane. Smooth outer surface of heart
Myocardium
Thick, middle layer of heart. Cardiac muscle
Endocardium
Smooth, inner surface of the heart chambers
Pectinate muscles
Muscular ridges in auricles and right atrial wall
Crista terminalis
Ridge separate pectinate muscles from smooth atrial wall
Trabeculae carneae
Interior walls of ventricles. Large muscular ridges and columns
Auricles
Extensions of atria that be seen anteriorly between each atrium and ventricle
Superior and inferior vena cava
Carry blood to right atrium
Four pulmonary veins
Blood from lungs to left atrium
Two arteries that exit heart
Aorta, pulmonary trunk
Coronary sulcus
Runs obliquely around the heart, separates atria from ventricles
Anterior and posterior interventricular sulcus
Division between left and right ventricles
Right and left coronary arteries
Supply heart. Lie within coronary sulcus and interventricular sulci
Anastomoses
Direct connection between arteries of heart
Coronary sinus
Veins from heart itself drain into here, then right atrium
Right atrium openings
Superior/inferior vena cava and coronary sinus
Interatrial septum
Divides two atria
Fossa ovalis
Oval depression on right side of septum marking former location of foramen ovale
Foramen ovale
Opening between the right and left atria in the embryo and fetus
Papillary muscles
In both ventricles. Cone shaped muscular pillars
Chordate tendineae
Attached to papillary muscles and atrioventricular valves. Thin, strong connective tissues.
Function of papillary muscles
Contract when ventricles contract. Prevent valves from opening into atria by pulling on chordae tendineae.
Heart skeleton
Plate Of fibrous connective tissue between atria and ventricles
Fibrous rings
Connective tissue plate forms fibrous rings around atrioventricular and semilunar valves.
Heart skeleton functions
Support, reinforce valve openings, electrical insulation, point of attachment
Cardiac muscle cells
Elongated, branching cells that have one or two nuclei.
Smooth sarcoplasmic reticulum
Cardiac muscle. Not arranged.
Intercalated disks
Binds cells end to end
Desmosomes
Hold cells together
Gap junctions
Allow cytoplasm to flow freely between cells. Low electrical resistance between cells
Conducting system
Relays action potentials through the heart
Sinoatrial node location
SA node. Right atrium, near superior vena cava
Atrioventricular node
AV node. Medial to the right atrioventricular valve.
Bundle of His
Atrioventricular bundle. From AV node. Travels to septum, splits to right and left branches
Purkinje fibers
Inferior terminal branches of the bundle. Electrical signals pass rapidly.
Resting membrane potential
Low permeability to Ca2+ and Na+. Higher permeability to K+.
Ectopic focus
Any part of the heart other than the SA node that generates a heartbeat
Absolute refractory period
Cardiac muscle cell is completely insensitive to further stimulation
Relative refractory period
Cell is sensitive to stimulation, but greater than normal stimulus to cause AP
Electrocardiogram
Summated record of the cardiac action potentials
P wave
Depolarization of atrial myocardium
QRS complex
Ventricular depolarization (contraction)
T wave
Repolarization of ventricles. (Relaxation)
Systole
Contract
Diastole
Dilate
When used alone, systole and diastole
Refer to ventricular systole and diastole.
Determines direction of blood movement
Chamber pressure
Heart valves
First heart sound
Low pitched “lubb”. Atrioventricular valves close.
Second heart sound
Higher pitched “dupp”. Closure of aortic and pulmonary semilunar valves.
Third heart sound
Thin, young. Turbulent blood flow into ventricles.
Dicrotic notch
Aortic valve closes, causing higher pressure in aortic pressure curve. Pressure caused by recoil creates double pulse
Mean arterial pressure
MAP=CO X PR
Cardiac output
Peripheral resistance
Peripheral resistance
Total resistance against which blood must be emptied.
Cardiac output
Heart rate X stroke volume
Cardiac reserve
Difference between cardiac output when at rest and maximum cardiac output
Intrinsic regulation
Hearts own regulatory function.
Extrinsic regulation
Epinephrine and norepinephrine from adrenal medulla
Sympathetic and parasympathetic
Preload
Extent to which ventricular walls are stretched
Starling law of the heart
Relationship between preload and stroke volume. Pumping effectiveness
Afterload
Pressure left ventricle must produce to overcome pressure in aorta.
Parasympathetic control
Vagus nerve. Inhibitory influence. Acetylcholine
Sympathetic control
Thoracic and spinal nerves. Increase heart rate, force of contraction. Norepinephrine
Hormonal control
Epinephrine and norepinephrine from adrenal medulla. Increase rate and force
Baroreceptor reflexes
Regulate blood pressure. Carotid and aorta
Chemoreceptor reflexes
Regulate hearts activity. Sensitive to pH and CO2
Cardio regulatory center
Sensory action potentials integrated. Medulla oblongata
Heart block
Excess K+ in tissue heart rate and stroke volume decrease. Loss of AP conduction
Endothelium
All blood vessels have this internal lining
Pericapillary cells
Between basement membrane and endothelial cells. Fibroblasts, macrophages, smooth muscle
Continuous capillaries
No gaps between endothelial cells. Muscle, nervous tissue