Anatomy of the heart: Gilland Flashcards
What is the fold difference between the atria and ventricles?
The atria and ventricles can pump side by side for 2-3 billion cycles while maintaining a 4 to 8 fold difference in the systemic/pulmonary pressures
What maintains the seperation of the two circuits (pulmonary and systemic)?
The integrity of atrial and ventricular septa
Efficient pumping mechanism depends on what?
Depend on controlled spreading of myocyte excitation initiated at the SA pacemaker and relayed to the ventrciles by the cardiac conduction system
What regulates cardiac activity?
Vagal and Sympathetic interaction with myocardium and intrinsic cardiac neurons
Normal Aortic pressure
120/80 mm Hg
What is the distribution of blood in the body?
Heart - 15%
Brain - 15%
Liver - 10%
Intestine - 25%
Kidney - 20%
Skin ,skeletal, trunk, limbs - 25%
What is the anterior, inferior, and superior attachment of the pericardium?
Anterior - to fascia on deep surface of sternum
Inferiorly - to the central tendon of the diaphragm
Superiorly - to the great vessels
What is the fibrous pericardium?
- a tough conical collagenous, with small elastic fibers, cloak encasing the heart.
- Base is attached to the diaphragm
The lower portion of superior vena cava, aorta, and pulmoary trunck are encased in what?
Encased in pericardium
What provides innervation to the pericardium and diaphragm?
Phrenic nerve
(C3-C5)
Pericardial Cavity
potential space between parietal and visceral pericardua
Contains smal amount of pericadial fluid
(15-50mL)
What are the serous pericardial layers?
Parietal pericardium
Visceral pericardium (epicardium)
exude pericardial fluid which reduces friction during heart motion
Parietal PEricardium
shiny inner surface
Fused with fibrous pericardium
SENSITIVE TO PAIN
(innervation from afferent fibers of the phrenic nerve)
Pericardial pain is referred to where?
Referred to supraclavicular skin on the same side
Visceral pericardium (epicardium)
forms outer surface of heart
Covers myocardium and epicardial fat
Endocarium is made up of what?
squamous epithelium continuos with endothelium of arterial and venous system
What are the two spaces where fliud can collect within the pericardial cavity?
Oblique pericardial sinus
Transverse pericardial sinus
What is Cardiac tamponade?
Accumulation of fluid in pericardial space, whether from bleeding, over production of pericardial fluid or other causes results in increased pericardial pressure and eventual progressiely reduced ventricular filling.
Do you develop cardiac tamponade with slow accumulaiton of fluid?
Not initally
Slow accumulation of fluid can allow for stretching of pericardum, with build up of a liter of fluid before even getting Tamponade
Rapid accumulation, as with severe bleeding, allows no time for stretching of the pericardium. What this lead to?
Tamponade can occur with as liitle as 100 mL of fluid
Cardiac Tamponade results in what?
Pulmonary Edema
Shock
Death
When you orient the heart, Ventricles are _____ and Atria are ____.
Ventricles anterior
Atria posterior
What does the coronary sulcus seperate?
Seperate atria muscle from ventricle muscle
What forms most of the inferior surace of the heart?
Right ventricle
Sits on Central tendon
Which three structures are oriented along a verticle line in anatomical position?
Superior vena Cava
Right Atrium
Inferior Vena Cava
What is the purpose of the fibrous skeleton of the heart?
- Provides a strong framework for attachment of cardiac muscle fibers
- physically seperate atrial and venricular myocardia and blocks the spread of myocardial excitation across the atrioventricular border (coronary sulcus)
- support all 4 heart valves by provideing anchoring rings and also forms fibrous ribs in the semilunar valves
The fibrous skeleton comprise of what three things?
Fibrous rings
Fibrous trigones
Membranous portion of interventricular septum (septum membranacecum)
Fibrous rings
(partial)
around valves (anunuli fibrosi) and extension into semilunar leaflets
Fibrous trigones
between aortic valve and atrioventricular valves (trigone fibrosa)
What are the 4 openings in the Right atrium?
Superior vena cava
Inferior vena cava
coronary sinus
anterior cardiac sinus
right ventricle expansion (RV diastole) does what?
Sucks blood from R. Atrium, SVC, IVC, and Coronary SInus
Contraction of the R atrium (systole) is known to what the ventricle?
“Top Off”
It is the final volume before ventricular systole (contraction)
What anchors the valves?
They are anchored by a surrounding fibrous ring known as annulus
During ventricular systole, attachment to the tendinous cords and papillary muscles prevents what?
Prolapse of the valve leaflets into the right atrium by arresting the leaflets exactly in contact with one another
If the cusps do not meet precisely during slosure they will leak. This is know as?
Regurgitation
Failure of a valve to open widely during ventricular diastole is known as?
Valve stenosis
Why is the septomarginal trabecula (moderator band) so important?
Holds conduction fibers
What is the purpose of the nodule on the aortic cusps?
reinforcement in the center of the edge of each cusps.
The three nodules meet in the middle where the valves close.
When do the aortic valves open and close?
Open: When left ventricular pressure exceeds aortic pressure
Close: when ventricular pressure drops
Majority of valve replacements involve which two valves?
Mitral and aortic valve
Disruptonof the conduction system of the heart leads to what?
Arrythmogenic heart
What is hypertrophic cardiomyopathy?
Thickning of the walls and reduction of volume in the ventricles
Dilated Cardiomyopathy
Left ventricle enlarged with thin walls
What forms the pacemaking cells and distribution structures that defines the spatiotemporal pattern of cardiac excitation?
Special Myoepithelial Cells
What blocks conduction from atrium to ventricle?
Fibrous tissue in coronary groove
Where does the Right bundle branch run and terminate as?
Runs along moderator band and anterior papillary muscles and terminate as purkinje fibers
Spread of excitation through atria and to the AV node may result from what?
Largely from ordinary atrial myocyte excitaiton
There are also internodal and Bachmann’s fibers
Where does the excitation of the AV node first occur?
In the apex of the heart
Where does the Left bundle branch run?
run down septal wall and then fans out on papillary muscles nad extends fibers throughout apical region
What initates the cardiac cycle?
Myogenic activity inthe SA node
What modulates the cardiac cycle?
Sympathetic and Parasympathetic input modulates
Modulate rate, force, and output
The autonomic nerves and ganglion cells act on what?
Nodal tissues
conduction bundles and terminal fibers
coronary vessels
directly on the atrial and ventricular musculature
Sympathetic activity _______ the heart and _______ the coronary arteries
Accelerates
dilates
Parasympathetic (vagus) activity ____ the heart and _____ the coronary arteries
Slows
Constricts
Are the vagal cardiac nerve pre or post ganglionic?
PREGANGLIONIC parasympathetic fibers
Are the sympathetic cardiac nerves pre or post ganglionic?
POSTGANGLIONIC fibers
All of the cardiac branches of the vagus and all the sympathetic branches contain both affernt and efferent fibers except?
The Cardiac branch of the Superior Cervical Sympathetic Ganglion is entirely EFFERENT
What are the three vagal cardiac nerves?
Superior cervical vagal cardiac nerve
Inferior Cervical Vagal Cardiac Nerve
Thoracic Vagal Cardiac NErve
The autonomic cardiac nerve supply the heart by way of ?
By way of the cardiac plexus
This is located on the posterior surface of the aortic arch and pulmonary trunk/arteries, immediately anterior to the bifurcation of the trachea.
What is the coronary plexus?
extension of the cardiac plexus along the coronary arteries
What is the pulmonary plexus?
vagal and sympathetic fibers innervate the bronchial tree and visceral pluera
The largest group of cardiac ganglia are located near where?
The SA node and AV nodes
Where are the smaller groups of cardiac ganglia located?
Upper part of the left atrium
Interatrial septum
junctions of atria and auricles
base of the great vessels
base of teh ventricles
Which areas of the heart are devoid of cardiac ganglia?
Right atrial free wall
atrial appendages
trunk of great vessels
most of the venricular myocardium
Majority of the neurons in cardiac ganglia are local circuit neurons which synapse where?
on other ganglia
What does it mean when the heart is Left dominant?
PAD is coming of the Left coronary artery instead of the Right coronary arter
also if there is no Right coronary artery the branches are all coming off the left coronary artery
What does it mean when the heart is balanced?
Right coronary artery braches into right marginal and Posterior Interventricular brach
Left coronary artery branches into circumflex and LAD
What does it mean when the heart is right dominant?
The circumflex artery instead of coming off the left is now coming off the right. Right coroanry artery also has PAD and Right marginal. Only branch on Left coronary artery is LAD
Where along the large coronary arteries are collaterals located?
The heart does not have much collaterals but there is anastamosis along the distal end of the coronary arteries branches. This allows for some bidirectional flow between main branches.
Are the anastamosis in the heart sufficient to provid colateral pathways around large coronary blocks?
NO
The great cardiac vein becomes what?
THe coronary sinus
Where does the anterior cardiac vein drain into?
Right atrium
What are Thebsian veins?
Thees are the smallest cardiac veins.
Located mostly in right atrium and ventricle
When coronary blood flow greatest?
During ventricular diastole, especially for the left coronary artery
When does flow drop? Peak?
Drops to zero as systole begins
Peaks at the beginning of diastole when the ventricles relax
