Heart Flashcards
(25 cards)
what type of cell forms the outer surface of the heart?
flattened mesothelial cells
what are the internal heart walls covered in?
endothelial cells
is the myocardium made of multinucleate cells?
no, it is made from mononuclear cardiac myocytes
what is syncytium?
a multinucleated mass of cytoplasm not separated by individual cells
does the myocardium have a syncytium?
no, each cell has its own central nucleus.
are atrial myocytes bigger or smaller than ventricular myocytes?
smaller - especially those of the right atrium.
what granules do cardiac myocytes secrete?
Atrial natriuretic peptide (ANP) - a neuroendocrine granule.
when is ANP secreted by myocytes?
when cells are stretched excessively
what does ANP do?
increases the excretion of water and sodium and potassium ions by the distal convoluted kidney tubule. decreases blood pressure by inhibiting aldosterone and renin production.
what do intercalated discs do?
they join cardiac myocytes together and electrically couple cells.
what are intercalated junctions made of between cardiac myocytes?
contains gap junctions, desmosomes and adherent junctions.
what is a desmosome?
a structure which attaches 2 adjacent cells, formed by protein plaques in the cell membrane - linked by filaments.
What are the 3 layers of valves?
Fibrosa, spongiosa, ventricularis
what is the fibrosa layer in valves made of and on which side does it sit?
dense fibrous connective tissue, and it sits on the aortic side of the valve.
what is the spongiose layer in valves made of and on which side does it sit?
loose fibrous connective tissue, and it sits in the middle layer.
what is the ventricularis layer in valves made of and on which side does it sit?
made of collagen and elastin, and sits on the ventricular side.
what cell type covers valves all around?
endothelial cells
what are nodes composed of?
small, irregularly arranged myocytes adapted for electrical conduction - surrounded by blood vessels and nerve plexus.
where is the sinoatrial node located?
on the medial side of the junction between the superior vena cava and the right atrium.
where is the atrioventricular node located?
located at the base on the right-atrial septum, anterior to the opening of the cardiac sinus.
where are the Purkinje fibres located?
beneath the endocardium (subendocardium) in the interventricular septum.
what are Purkinje fibre cells like?
cells have large vacuoles, few myofibrils, stain pale with H&E, lots of glycogen, regularly arranged - form a parallel bundle.
whats the visceral pericardium made of?
covered with flat mesothelial cells, rests on a basement membrane and a thin layer of loose fibrous and elastic tissue.
what is the endothelium made of?
single layer of vascular endothelial cells, supported by a basement membrane and loose fibrous and elastic tissue.
