Cardiovascular Part II: Heart Flashcards
What are the two circuits of the cardiovascular system? And what does each do?
Pulmonary Circuit - transports blood between lungs and heart
Systemic Circuit - transports blood between the body tissues and the heart
What are the receiving chambers of the heart? And where does each receive blood from?
Atria
- right receives oxygen-poor blood from body
- left receives oxygen-rich blood from lungs
What are the pumping chambers of the heart? And where does each send blood to?
Ventricles
- right sends oxygen-poor blood to lungs via pulmonary trunk
- left sends oxygen-rich blood to body via aorta
What are the functions of the heart?
- ensure unidirectional blood flow
- pump blood to lungs and body
- develops blood pressure for nutrient and waste exchange
Describe the position and orientation of the heart.
- it is the largest organ in the mediastinum
- medial to the lungs
- obliquely positioned
- posterior to sternum
- rests on superior surface of diaphragm
- apex (anteroinferior left) in 5th intercostal space
- base is a broad posterior surface
6
Parietal Pericardium
- the layer of serous pericardium that lines the walls of the pericardial cavity
7
visceral pericardium
- the layer of serous pericardium that lines the outside of the heart
- AKA epicardium (when asked for “layer,” not “covering”)
the layer of tissue indicated by the arrow in the magnified portion of the image
fibrous pericardium
- strong outer layer of dense connective tissue surrounding the serous pericardium
the heart covering formed from both layers #6 and #7
serous pericardium
- “fist in a balloon” type covering
- interior of “balloon” = pericardial cavity with pericardial fluid
What are the three layers of the heart wall from outermost to innermost?
- Epicardium - visceral pericardium
- Myocardium - middle layer of cardiac muscle
- Endocardium - inner endothelium on layer of CT
How is myocardial muscle oriented and what does this achieve?
- it is a spirally-arranged network of cardiac muscles bound by connective tissue
- it produces a wringing, squeezing motion
What are the four chambers of the heart? Which receive and which discharge blood?
Receiving Chambers:
- Right atrium
- Left atrium
Discharging Chambers:
- right ventricle
- left ventricle
Right Atrium
- receives oxygen-poor blood from systemic circuit (inf. and sup. vena cava)
- contains fossa ovalis
Chamber numbered 3
Left atrium
- makes up posterior surface of heart
- receives blood from lungs via pulmonary veins
chamber marked with pen
right ventricle
- receives oxygen-poor blood from right atrium via right AV valve and pumps it to pulmonary trunk via pulmonary SL valve
Left Ventricle
- externally forms apex of heart
- receives oxygen-rich blood from the left atrium via the left AV valve and pumps it via the aortic SL valve to the aorta
- has a thicker wall than the right ventricle because it must pump blood further, through the entire systemic circuit
7
epicardium
- known as visceral pericardium when refering to heart coverings
- most superficial layer of the heart
- lubricates heart
6
myocardium
- middle layer of cardiac muscle in heart wall
- thickest layer of heart
- arranged spirally to contract in a wringing motion
5
endocardium
- deepest layer of heart
- lines inner surface
- made up of endothelial & connective tissues
Incoming Vessels of the Heart
Right Atrium (oxygen-poor)
- superior vena cava
- inferior vena cava
- coronary sinus
Left Atrium (oxygen-rich)
- pulmonary veins (4 total, 2 L & 2 R)
Outgoing Vessels of the Heart
Right Ventricle —-> Pulmonary Trunk
Left Ventricle ——> Aorta
fossa ovalis
- oval depression in interatrial septum
- vestige of the fetal foramen ovale, a bypass of the pulmonary circuit
green area
interventricular septum
- wall between the two ventricles
indicated by green line
Apex
- inferior conical end of heart formed by exterior of inferior left ventricle
the posterior face of the heart
Base
- broad posterosuperior surface of heart
- primarily formed by left atrium
area circled in green
right auricle
- wrinkled, flaplike extension of right atrium
6
left auricle
- wrinkled extension of left atria
What are the two different kinds of valves in the heart and what are their functions?
atrioventricular valves
- between atria and ventricles
- bicuspid on left, tricuspid on right
semilunar valves
- between ventricles and arteries (one pulmonary, one aortic)
- 3 pocket-like (“half-moon”) cusps
- both serve to allow only unidirectional flow of blood
5
Mitral Valve (AKA bicuspid valve)
- left atrioventricular valve
2
Tricuspid Valve
- right atrioventricular valve
1
pulmonary semilunar valve
- between right ventricle and pulmonary trunk
9
aortic semilunar valve
- between left ventricle and aorta
What are the cusps of cardiac valves made of?
- they are flaps of endocardium over a core of dense CT
white fibers shown here:
Chordae Tendineae
- thin strands of collagen fibers connecting cusps of AV valves to papillary muscles
- prevents the valves from everting into the atria
7
papillary muscles
- cone-shaped muscular projections from the walls of the ventricles which anchor chordae tedineae
10
Aorta
- largest artery in the body
- accepts blood from left ventricle
9
Pulmonary Trunk
- anterior to aorta
- divides into left and right pulmonary arteries
- accepts blood from right ventricle
2 and #6
Pulmonary Veins
- enter left atrium from lungs
- two sets of two, left and right
4
superior vena cava
- large posterosuperior vein
- returns blood from head, neck and upper extremities
- enters right atrium of heart
1
inferior vena cava
- returns blood from abdomen and lower extremities
- enters right atrium
Cardiac Muscle
- forms middle layer of heart called myocardium
- striated
- contracts via sliding filament mechanism, similar to skeletal muscle
- involuntary
- contracts to pump blood through heart and into vessels
Cardiac Muscle Cell Characteristics
- short (unlike skeletal muscle)
- branching
- 1-2 central nuclei
- not fused colonies
intercalated disks
- complex junctions between cardiac muscle cells
- interlocking of adjacent sarcolemmas (muscle cell membranes)
- have cell junctions: adhering and gap junctions
What is a cardiac muscle “fiber”?
Multiple short cardiac muscle cells lined up and connected by intercalated discs
(unlike skeletal muscle fibers which are a single, long muscle cell)
What separates different cardiac muscle fibers?
endomysium
- connective tissue with blood vessels and nerves
- binds adjacent cardiac fibers, but seperates their cells
How do most cardiac muscle cells receive contraction signals?
- most are NOT innervated
- they receive signals through gap junctions of intercalated disks
What are the specialized cells that conduct electrical impulses through the heart?
Conduction System Cells
- specialized cardiac muscle cells
- cause chambers to contract in the proper sequence
Autorhythmicity
- a property of cardiac muscle cells
- rhythmic activity without being driven by rhythmic external stimulation
area from which signals are spreading here:
- sinoatrial node -
- specialized cardiomyocytes
- in the superior wall of right atrium
- sets inherent rate of contraction
- impulses spread to the atria
2
atrioventricular node
- in inferior wall of interatrial septum
- electrically connects atrial and ventricular chambers
7
Atrioventricular Bundle (AKA Bundle of His)
- collection of heart muscle cells specialized to conduct impulses from the AV node to the bundle branches and Perkinje fibers which stimulate ventricular contraction
6
- left and right bundle branches
- branches of the AV bundle which conduct impulses to the left and right ventricles
rounder, emptier cells in center of image
Purkinje fibers
- specialized conductive fibers in ventricular walls
- larger size makes for easier ion flow & signal conduction
- bigger, emptier-looking cells among normal cardiac muscle cells
Cardiac Innervation (which nerves?)
- rate altered by external controls
Nerves to Heart:
- Vagus nerve (parasympathetic branch)
- Sympathetic fibers (from cervical and upper thoracic chain ganglia)
- Visceral sensory fibers
red vessel indicated by arrow
left coronary artery
- splits into:
- anterior interventricular artery
- circumflex artery
- posterior interventricular artery
general term for all vessels shown here in red
coronary arteries
- vessels which supply blood to the myocardium
- arise from the aorta
part B
coronary sinus
- largest coronary vein
- where blood re-enters right atrium from coronary circulation
anterior interventricular artery
circumflex artery
9
posterior interventricular artery
8
right coronary artery
- leads to right marginal artery at bottom of right ventricle
8
marginal artery
- branches off of right coronary artery
blue vessel here:
great cardiac vein
- vein that runs along anterior surface of heart between ventricles (along with anterior interventricular artery)
middle cardiac vein
middle cardiac vein
- runs along posterior heart between ventricles
- paired with posterior interventricular artery
part G
internodal pathway
- carries signals from the sinoatrial to atrioventricular nodes of the cardiac conduction system
