Histology of the Heart Flashcards
How is atrial endocardium different from ventricular endocardium?
Atrial endocardium is thicker, with a thicker underlying stromal layer.
3 layers of epicardidum, from outside in?
Serosa
Adipose
Myocardium
What are the annuli fibrosi?
Rings of dense, collagenous connective tissue that anchor each heart valve.
They’re connected to the fibrous skeleton of the heart.
What separates, electrically, the atria from the ventricles?
The fibrous skeleton of the heart.
What kind of cells are Perkinje cells?
Neuron-ish myocytes - they conduct electrical signals much more quickly than do normal myocytes.
What allows Perkinje cells to transmit signals so quickly?
Lateral gap junctions and intercalated discs.
How are the deep, middle, and superficial muscle layers of the heart oriened?
Deep: Longitudinal
Middle: Circumferential
Superficial: Oblique (for “wringing” motion)
Are the deep, middle, and superficial muscle layers interconnected by gap junctions, etc.?
Yep - this helps make sure all the layers contract together.
Do cardiac myocytes have lots of mitochondria?
Yep. They love to use glucose and fat.
How does the rigidity (resistance to stretching) of myocyte sarcomeres compare to that of skeletal muscle?
Myocyte sarcomeres are way more resistant to stretching.
this contrasts to skeletal muscle being not very strong when it’s overextended
Why does cardiac muscle have more consistent contractile strength as length varies?
(at least in part…) Due to the arrangment of myosin heads - there are myosin heads throughout the length of the myosin parts, instead of just at the ends. (see the picture on the slide)
Does cardiac muscle have lots of capillaries and mitochondria and T-tubules?
yep
What special additional function do atrial myocytes have?
Endocrine function: They secrete natriuretic peptides -> natriuresis, vasodilation, and suppression of the renin-angiotensin-aldosterone system. (i.e. they try to lower BP)
They’re often used as biomarkers for heart function.
