Pulmonary Circuit
blood vessels that carry blood to and from the heart
Systemic Circuit
vessels that transport blood to and from all body tissues
Right and Left Atria
Recieving chambers of the heart
Right and Left Ventricles
pump blood around the 2 circuits
Location of the heart in the Thorax
Posterior to the sternum and costal cartilages. Heart rests on the superior surface of the diaphragm. Largest organ in the mediastinum (region between the 2 lungs).
Apex lies to the LEFT of the midline and anterior to the rest of the heart.
Heart's BASE i
Functions of the Heart:
1.the right side of the heart receives oxygen poor blood from the body tissues and then pumps this blood to the lungs to pick up oxygen and dispel carbon dioxide
2. Left side receives the oxygenated blood returning from the lungs and pumps this blood thro
What is the Pericardium?
A triple layer sac that encloses the heart.
Fibrous Pericardium.
Outer layer of the heart's pericardium.
Strong Layer of dense connective tissue
Adheres to the diaphragm inferiorly and superiorly fuses to the roots of the great vessels that leave and enter the heart.
Acts as a touch outer coat that holds the heart in p
Serous Pericardium.
Part of heart's pericardium.
Deep to the fibrous pericardium
Double layered sac sandwiched between the fibrous pericardium and the heart
Parietal Layer of Serous Pericardium
adheres to the inner surface of the fibrous pericardium
this layer is continuous with the visceral layer
Visceral Layer of Serous Pericardium
Also called EPICARDIUM
lies on the heart and considered part of the heart wall
visceral layer is continuous with the parietal layer
Pericardial Cavity
Slit-like space between the visceral and parietal layers of the serous pericardium.
Epithelial cells of the serous pericardium that lines the pericadial cavity secrete lubricating fluid of seroud fluid into the pericardial cavity.
The fluid helps reduce f
How many layers does the heart wall have? Name them.
3
Epicardium (superficial)
Myocardium (Middle layer)
Endocardium (deep)
Epicardium
part of the heart wall
actually is the visceral layer of the serous pericardium
often infiltrated with fat in older people
Myocardium
Middle layer of the heart wall
Forms the bulk of the heart.
Consists of cardiac muscle tissue
this layer actually CONTRACTS
Fibrous Skeleton of the heart
cardiac muscle cells of the myocardium are surrounded with connective tissues that bind cells into elongated, circularly and spirally arranged networks called BUNDLES
These bundles function to squeeze blood through the heart in the proper direction
Connec
Endocardium
Deep to the myocardium
sheet of simple squamous epithelium resting on a thin layer of connective tissue
Lines the heart chambers and covers the heat valves
Interatrial Septum
wall between the atria
divides the atria internally
Intercentricular Septum
wall between the ventricles
divides the ventricles internally
Coronary Sulcus
Forms a "crown" by circling the boundary between the atria and ventricles.
External boudary of the chambers
Anterior Interventricular Sulcus
marks the posterior position of the interventricular septum between the two ventricles
posterior interventricular sulcus
separates the two ventricles on the heart's inferior surface
posterior" of the heart lies against the diaphragm and is thus its inferior surface
...
Right Atria
Forms entire right border of heart
Recieving chamber for oxygen-poor blood returning from the systemic circuit
Receives blood from 3 veins:
superior vena cava
inferior vena cava
coronary sinus
Right Ventricle
forms the most anterior surface of the heart
Receives blood from the right atrium and pumps blood into the pulmonary trunk (artery).
Trabeculae carneae
located on right ventricle walls
these are irregular ridges of muscles
Papillary Muscles
cone shapped
project from the walls of the ventricular cavity
Chordae Tendineae
heart strings"
project superiorly from the papillary muscles to the flaps (cusps) of the tricuspid (right anterioventricular) valve
Pulmonary Semilunar Valve (or just pulmonary valve)
on superior surface of right ventricle
opening between the right ventricle and the pulmonary trunk
Left Atrium
makes up heart's most posterior surface, or base
Receives oxygen-rich blood returning from the lungs through two right and two left PULMONARY VEINS
Left atrium opens into the left ventricle through the MITRAL VALVE
Left Ventricle
Forms the apex
Dominates heart's inferior surface
Pumps blood into the systemic circuit
Contains Trabeculae carneae and papillary muscles
contains chordae tendineae, and cusps of an antrioventricular (mitral) valve
Right atrioventricular valve
tricuspid
has three cusps
Left atrioventricular valve
bicupsid or mitral valve
has only 2 cusps
Aortic and Pulmonary Valves
aka semilunar valves
these valves are located at the junction of the ventricles and the great arteries
each valve has 3 pocket like cusps shaped roughly like crescent moons
these valves prevent back flow from the great arteries into the ventricles
atrioventricular valves
prevents back flow of blood into the atria during contractions of the ventricles
The chordae tendineae and papillary muscles that attach to these valves look like the cords of an open parachute, limiting the closed cusps so they cannot fly up and allows reflex of ventricular blood in the atria.
...
Sinoatrial (SA) node
where heartbeat begins.
A crescent shaped mass of muscle cells that lies in the wall of the right atrium, just inferior to the entrance of the superior vena cava.
Sets the basic heart rate by generating 70-80 electrical impulses per minute.
Heart's pacema
Internodal pathway
the structure the signal from the SA node travels down to the atrioventricular (AV) node
Atrioventricular (AV) node
located in the inferior part of the interatrial septum.
AV node delays signal for a slight second.
after delay, the impulses race through the atrioventricular bundle (bundle of His)
What is the atrioventricular bundle also called?
Bundle of His
ANS heart innervation
Parasympathetic Fibers - slow heart rate
Sympathetic Fibers - increase the heart rate and force of heart contraction
Autonomic innervation to heart is controlled by CARDIAC CENTER in the reticular formation of the medulla oblongata of the brain.
Cardioinh
Where does the parasympathetic fibers innervate the heart?
fibers arrise from braches of the vagus nerve in the neck and thorax
para innervation is restricted to SA and AV node and the coronary arteries. thus only heart beat is influenced by parasympathetic fibers
Where do the sympathetic fibers innervate the heart?
Nerves travel to the heart from the cervical and upper thoracic chain ganglia
fibers innervate SA / AV nodes (like parasympathetic) but ALSO innervate cardiac musculature throughout the heart. Thus it affects both rate and strength of contraction
What supplies blood to the heart?
Right and Left Coronary Arteries
What supplies blood to the left atrium and posterior part of left ventricle?
Circumflex Artery
What are the arteries that make up the left coronary artery?
Circumflex Artery
Anterior Interventricular Artery
What are the arteries that make up the right coronary artery?
Marginal Artery
Posterior Interventricular Artery
Anterior Interventricular Artery
branch of Left Coronary Artery
descends in anterior interventircular sulcus toward apex
sends branches into the interventricular septum and onto the anterior walls of both ventricles
Circumflex Artery
branch of Left Coronary Artery
Follows coronary sulcus posteriorly
Supplies: left atrium and posterior part of left ventricle
Marginal Artery
Branch of Right Coronary Artery
Supplies Right Ventricle
Posterior Interventricular Artery
branch of Right Coronary Artery
in posterior interventircular sulcus
Coronary Sinus
Returns almost all venous blood from the heart to the right atrium
Located: posterior part of the coronary sulcus