Histo Exam 2-Heart study guide Flashcards
What is the bulk of the heart muscle?
myocardium
What is the layer that lines the chambers of the heart?
endocardium
What are the outermost layers of the heart?
pericardium
What is direectly attached to the surface of the myocardium?
epicardium
What is the endothelium?
simple squamous epithelium with a thin continuous basal lamina
Where is this endothelium found?
contacts blood within the chambers of the heart
What is subendothelium?
loose connective tissue layer with abundant elastic fibers and some smooth muscle bundles
What is subendothelium comparable to?
lamina propia
What is subendocardium?
layer of loose connective tissue
What does the subendocardium contain?
small vessels, nerves, bundle branches and purkinje fibers
Where is the subendocardium found?
connected to myocardium
Why is there collagen and elastin in the endocardium?
lots of collagen and elastin to allow for expansion and contraction of heart, allows for flexibility
Why are there smooth muscle bundles in the endocardium?
smooth muscle helps endocardium contract back to normal size
What does the myocardium consist of?
consists of cardiac muscle fibers, part of the cardiac skeleton, and the impulse-conduction system of the heart
What surrounds each cardiac muscle cell?
surrounded by endomysium
What are groups of cardiac cells surrounded by?
perimysium
What are characteristics of cardiac muscle?
striated, branched, single central round nucleus, intercalated disks
What are intercalated disks?
gap junctions and fascia adherens
What do you look for in cross sections of cardiac muscle?
look for central nuclei and bundled myofilaments
What is atrial cardiac muscle made of?
overlapping network of woven fibers with collagen and elastin interspersed
What do atrial cardiac cells synthesize?
the hormone atrial natriuretic factor
Atrial cardiac muscle conducts impulses_________ and contract ________rhythmically than ventricular cardiac muscle cells.
faster, more
Does atrial have more or less gap junctions than ventricular cardiac muscle cells?
more gap junctions
What are the characteristics of the endocardium and myocardium in atrial cardiac muscle?
thicker endocardium and thinner myocardium
Specifically where is more ANF synthesized?
in the right atrium
What is the purpose of ANF?
targets the kidneys and stimulates sodium and water loss and reduces blood pressure
What is a characteristic of ventricular cardiac muscle?
thicker myocardium than atria, larger less granular cardiac myosites, less elastic fibers
How are cells positioned in ventricular cardiac muscle?
helically around the cavity
Why are ventricular cardiac cells winding helically around the cavity?
to aid in “wringing out” the heart during contraction
What is another name for epicardium?
visceral pericardium
What is epicardium made of?
outer single smooth layer of squamous mesothelial cells with thin basal lamina
What is the subepicardial laer made of?
loose connective tissue binds epicardium to myocardium
What is also found in the epicardium?
contains variable amounts of adipose, within which coronary vessels are embedded
What is the cardiac skeleton?
dense connective tissue scaffolding into which cardiac muscle fibers insert and from which cardiac valves extend
What is the annuli fibrosae?
dense connective tissue rings that surround and reinforce valve openings
What is trigona fibrosae?
two triangular dense CT masses lying between the two groups of annuli fibrosae
What is the septum membranaceum?
dense fibrous plate forming the top of the muscular interventricular septum
What can happen to the cardiac skelton with age?
it may calcify
All four rings of this are associated with the 4 major heart valves?
annuli fibrosae
What are cardiac valves?
folds of endocardium enclosing a core of dense fibrous CT
What are the cardiac valves rich in?
rich in collagen and elastin
The bases of cardiac valves are anchored to?
stong fibrous rings of the annuli fibrosae
Where is the mitral valve located?
between the left atrium and left ventricle
What is another name for mitral valve?
bicuspid
What are the characteristics of the bicuspid valve?
has 2 cusps or flaps
What are the flaps anchored to?
papillary muscles
What holds the flaps to the papillary muscle?
chordae tendinae
What does the chordae tendinae insert into?
a fibrous cap in the myocardium
Where is the AV valve located?
located between the right atrium and ventricle
What is another name for AV valve?
tricuspid valve
How many flaps are on the tricuspid valvee?
3 cusps or flaps
What are the semilunar valves?
the aortic valve and the pulmonary valve
How many cusps are on the seminlunar valves?
3 cusps or flaps
What is unique to the semilunar valves?
no chordae tendinae and each cusp has a thickened nodule at the center of its free edge
What are the 3 distinct layers of the aortic cusp?
fibrosa, spongiosum, ventricularis
What is the fibrosa?
densely packed collagen
What is spongiosum?
proteoglycan and GAG matric with loosely arranged collagen
What is ventricularis?
abundant elastic fibers
What does the conduction system of the heart consist of?
consists of specialized cardiac muscle cells that are able to initiate and conduct electrochemical impulses
What does the conduction system include?
the sinoatrial node, the atrioventricular node, the bundle of His(av bundle), bundle branches and purkinje fibers
What are purkinje fibers?
conducting myofibrs
What is the SA node?
small mass of specialized cells found in the right atrium’s median wall adjacent to the opening of the superior vena cava within the terminal groove
Why do SA node cells serve as the pacemaker?
they have the fasted intrinsic rythym of contraction
What is the rate of contraction influenced by?
autonomic input
What are characteristics of cells of the conducting system?
large, pale cells, rich in glycogen with sparse myofibrils
What are purkinje fibers?
specialized impulse conducting cells
Where are purkinje fibers found?
in the subendocardium and myocardium
How do you differentiate purkinje fibers from typical cardiac myocytes?
larger and paler, with 1-2 central nuclei, intercalated disks and sparse myofilaments
What will be seen histologically with an acute myocardial infarction?
leukocytes and eosinophilic necrotic cardiac myocytes
What is seen histologically with older myocaridial infarcts?
dense connective tissue scar
