SFP: Heart Histology Flashcards
What is the difference between the visceral and parietal pericardium?
The visceral is in contact with the heart itself, and the parietal lines the inside of the sac.
What are the layers of the heart from superficial to deep?
Epicardium, myocardium, endocardium.
Describe the structure of the endocardium.
- It has an endothelium
- Subendothelial connective tissue layer containing smooth muscle and elastic fibers
- Subendocardial layer that contains connective tissue and merges with the myocardium.
Describe the structure of the epicardium.
- Mesothelium containing simple squamous epithelium and a basal lamina
- Supportive layer of loose connective tissue with blood vessels, fat, and nerves.
What is the function of fat in the epicardium?
It provides cushion.
What is the function of serous fluid?
It gives lubrication to allow the heart to move without friction.
What is the arrangement of cells in cardiac muscle?
Branching.
What are intercalated discs?
Regions of contact within interdigitating processes of cardiac muscle.
What will intercalated discs in transverse regions of the heart have?
Desmosomes and fascia adherens.
What will intercalated discs in longitudinal regions of heart muscle have?
Gap junctions to provide ionic continuity for a wave of contraction.
Describe the nucleus of cardiac muscle.
One nucleus that is centrally located.
Describe the contractile apparatus of cardiac muscle.
Composed of dyads containing a T tubule and 1 expanded terminal cistern of SR.
What is the arrangement of cells in the atria?
Overlapping networks (pectinate) impart a woven appearance
This structure allows for effective contraction of the atrial walls.
What is the arrangement of cells in the ventricles?
Complex cell layers that helically wrap around the ventricular cavity
This arrangement supports strong and coordinated contractions.
Are cardiac myocytes smaller in the atria or ventricles?
Atria
Atrial myocytes are generally smaller than ventricular myocytes.
What do atrial cardiac myocytes contain?
Granules containing Atrial Natriuretic Factor
This factor plays a role in regulating blood pressure and fluid balance.
Which has a more extensive T tubule system: atria or ventricles?
Ventricles
The extensive T tubule system in ventricles is important for rapid conduction of impulses.
Do atria or ventricles have more gap junctions?
Atria
More gap junctions facilitate rapid electrical conduction in the atria.
Which has more elastic fibers: atria or ventricles?
Atria
Atria contain pectinate muscles that increase elasticity.
Which conducts impulses faster: atria or ventricles?
Atria
Atria are designed to conduct impulses quickly to trigger contraction.
Do atria or ventricles contract more rhythmically?
Atria
The rhythmic contraction of atria is crucial for effective blood flow to the ventricles.
Where are lipofuscin granules typically found?
Atria
These granules are associated with aging and cellular stress.
What are the functions of the cardiac skeleton?
- Anchor and support valves
- Provide points of insertion for cardiac muscle
- Help coordinate heartbeat by acting as electrical insulation
The cardiac skeleton is essential for maintaining the structure and function of the heart.
What are the three parts of the cardiac skeleton?
- Annulus fibrosis
- Fibrous trigones
- Membranous septum
Each part plays a critical role in the structural integrity of the heart.
Describe the annulus fibrosis.
A component of the cardiac skeleton; dense connective tissue rings that reinforce valve openings in AV canals and at origins of the aorta and pulmonary artery
This structure is vital for preventing valve prolapse.
What are fibrous trigones?
A component of the cardiac skeleton; triangular dense connective tissue found between groups of annulus fibrosis.
What is the membranous septum?
A component of the cardiac skeleton; dense fibrous plate forming the top of the muscular interventricular septum.
What is the general composition of AV valves?
They’re folds of endocardium that enclose cores of dense connective tissue anchored in the annulus fibrosis.
Which valves are anchored and how?
Mitral and tricuspid; chordae tendineae anchor the valves to papillary muscles at the floor of the ventricle.
Describe the structure of chordae tendineae.
They have a central core of longitudinally oriented collagen fibers. At the periphery, they have loose collagen, elastic fibers, and proteoglycan-rich matrix.
What are the layers of semilunar valves?
The fibrosa, spongiosa, and ventricularis.
Describe the fibrosa of semilunar valves.
Contains dense collagen and a few elastic fibers.
Describe the spongiosa of semilunar valves.
Has proteoglycans and glycosaminoglycans, loose collagen fibrils, fibroblasts, and mesenchymal cells.
Describe the ventricularis of semilunar valves.
It is in direct contact with the endothelial layer of the ventricular surface. It is rich in elastic fibers.
Where is the SA node found?
The junction of SVC and crista terminalis in the right atrium.
What is a key landmark of the SA node?
The SA nodal artery; cells surround it.
Where is the AV node found?
Within the triangle of Koch defined by coronary sinus, septal leaflet of tricuspid valve, and membranous septum
The triangle of Koch is an anatomical region in the heart that is significant for the electrical conduction system.
Where is the AV bundle of His found?
Extends from AV node into the membranous septum
The AV bundle of His is crucial for transmitting electrical impulses from the atria to the ventricles.
What is the tendon of Todaro?
Collagen-rich structure that runs from the valve of the inferior vena cava toward the midline of the heart
The tendon of Todaro plays a role in the structure of the heart and the conduction system.
What is the function of the sinoatrial node?
It is the pacemaker of the heart
The sinoatrial node initiates the electrical impulses that regulate heartbeats.
What does the internodal pathway connect?
It connects the sinoatrial node to the atrioventricular node
This pathway is essential for the proper conduction of electrical signals in the heart.
What is the main role of Purkinje fibers?
Conducting electrical impulses
Purkinje fibers ensure rapid conduction of impulses throughout the ventricles.
How do conduction tissue and working myocardium compare?
Conduction tissue has smaller cells, more collagen, and more elastic fibers; it looks less organized
This structural difference is significant for their respective functions in the heart.
Describe Purkinje fibers.
They are not contractile cells; they are glycogen-rich and larger than working myocardium
Purkinje fibers are specialized for conducting electrical impulses and are linked by connexins.
Fill in the blank: The _______ is the pacemaker of the heart.
sinoatrial node
The sinoatrial node is crucial for initiating the heartbeat.
True or False: The AV bundle of His is located within the interventricular septum.
True
The AV bundle of His passes through the interventricular septum to connect to the bundle branches.
What structures make up the conduction system of the heart?
- Sinoatrial node
- Internodal pathway
- Atrioventricular node
- Atrioventricular bundle (bundle of His)
- Right bundle
- Left bundles
- Purkinje fibers
These components work together to ensure effective heart contractions.
purkinje fibers are mechanically and electrically coupled via ___
gap junctions and desmosomes
where in the heart are purkinje cells found
sub endocardium
what do myocytes have that purkinje fibers do not
intercalated discs
the diads in cardiac myocytes are located at the ___
z line
