Histology of the heart Flashcards
what are the layers of the heart inside the parietal pericardium
epicardium
myocardium
endocardium
what is the epicardium(5)
single layer squamous tissue
underlying connective tissue and fat
nerves (vagus and sympathetic)
coronary arteries which penetrate the myocardium
what is the myocardium and where is it thickest
relay of specialised cells
intercalated discs
gap junctions
thickest in L ventricle
what is heart endothelium (endocardium)
flattened endothelial cells
layer of supportive “tissue F” containing many elastic fibres which are continuous with connective tissue around myocytes and valves
do heart valves have any muscle
no
describe the tissue of heart valved
continous from the endothelium
less elastic, more dense collagen
LAMINA FIBROSA
re: tissue, why is it easier for blood to flow one way rather than the other through the aortic and pulmonary valves
3 layers of tissue:
ventricularis (elastic fibres, loose collagen)
spongiosa (proteoglycans and loose collagen)
fibrosa (dense and tough collagen)
makes it harder for backflow
where is the SAN located
between superior vena cava and right atrium
what staining is good to see specialised myocytes
trichrome
what colour are specialised myocytes when stained with trichome
pale pink
what does trichrome stain
connective tissue - blue
myocytes and AVN SAN pale pink
what are Purkinje fibres
massive myocytes
what are Purkinje fibres not
nerves
where is the AVN and why
embedded in connective tissue to delay the electrical signal getting to the ventricles
what organelles do PUrkinje fibres have a lot of
mitochondria
what do chordae tindinae attach to
T and M valves and papillary muscles
where are elastic fibres on ELASTIC arteries
tunica intima AND adventitia
How big are elastic arteries
> 10mm
how big are muscular arteries
0.1-10mm
describe the make-up of muscular arteries
fewer elastic arteries, more myocytes
what do muscular arteries have a leading role in
vasoconstriction
describe arterioles - size, constituents
<30um, 1-2 layers smooth muscle
what are the 3 types of capillaries
continuous
fenestrated
discontinuous
where are fenestrated capillaris
kidney, endocrine, synovial
where are discontinuous capillaries
liver, spleen, bone marrow
what are sinusoids
another name for discontinous capillaries
what is the role of arterioles
resistance, slows blood down so doesn’t damage capillaries
how do you recognise lymphatics
looks like a tear in the tisue; no red blood cells
have valves
what is plasma
blood without cells
what is serum
plasma without clotting factors or fibrin
what is the cellular makeup of blood
99% RBC
1%platelets and WBC
what is the makeup of plasma
90% water
7% albumin, IG and fibrinogen
3%solutes inc. gases
What are the signs of tamponade
Beck’s triad: elevated JVP, muffled heart sounds, tachycardia
What are the signs of tension pneumothorax
Tachycardia, elevated jvp, absent breath sounds
