C14. Histology of heart and blood vessels Flashcards
what does the cardiovascular system consist of
heart, arteries (elastic/muscular), arterioles, meta arterioles, capillaries, venules, post capillary venule, veins
name the 3 blood vessel layers
Tunica - Intima, media, adventitia
describe the inner layer of a blood vessel
tunica intima
single layer of squamous epithelial cells supported by basal lamina and a thin layer of connective tissue
describe the middle layer of a blood vessel
tunica media
made up of smooth muscle
thickness varies
describe the outer layer of a blood vessel
tunica adventitia made of supporting connective tissue
tunica intima and media are separated by a layer of what?
elastic tissue called internal elastic membrane
tunica media and adventitia are separated by a layer of what?
elastic tissue called external elastic membrane
when elastic fibres are specially stained, what colour do they stain
black
why are large arteries like the aorta termed elastic arteries
because they have many sheets of elastic fibres in their tunica media to provide elastic recoil
Large vessels, only the inner part of the wall can obtain nutrients from the lumen, therefore these vessels will have their own vascular supply called what?
Vasa Vasorum
describe arterioles structure
Arterioles have only one or two layers of smooth muscle in their tunica media and almost no adventitia.
arterioles have an important role of what
These are particularly important in controlling blood flow in a tissue.
what is interesting an different about meta arterioles
smooth muscle is replaced by discontinuous contractile cells called pericytes
where are capillaries absent
epithelial cells resting on basement membrane
epidermis of skin, hair and nail
cornea of eye
hyaline cartilage
what are capillaries composed of
endothelial cells and a basal lamina
what cells are often on capillaries at intervals just outside the basal lamina. And what type of cells are they
pericytes - connective tissue cells with contractile properties
name the 3 types of cappilaries
continuous
fenestrated
discontinuous (or sinusoidal)
where are continuous capillaries found
muscle, connective tissue, lung, skin, nerve
where are fenestrated capillaries found
mucosa of the gut, endocrine glands, glomeruli of the kidney
one type of capillary has large gaps and another has 50nm pores. which is which?
fenestrated have 50nm pores
discontinuous has large gaps
where are discontinuous capillaries found
liver, spleen and bone marrow
which type of capillary lacks a basal lamina
discontinuous
blood getting from a small arteriole to a post capillary venule has to go through other vessels to get there. Which vessels are these?
Metarterioles (MT)
Throughfare channels (TC)
Capillaries (C)
Precapillary sphincters (PS)
Post capillary venules are made up of what?
endothelial lines and have a thin layer of connective tissue and occasional pericytes
what are post capillary venules important for?
sites of exchange eg. cells moving into the tissue in inflammation
once post capillary venules gain more smooth muscle cells in their tunica media they become…? and what size are these generally?
venules
>50um
Vein have a thin/thick continuous/discontinuous tunica intima/media/adventitia choose from the options to complete the sentence
thin, continuous, tunica media
name the two largest veins
vena cava and hepatic portal vein
The largest veins (e.g. vena cava or hepatic portal vein) have a …….. tunica adventitia which incorporates bundles of ……… …….. smooth muscle.
thick
longitudinally oriented
which vessels contain the most blood in the body
veins
veins contain what structure
valves
what are valves
inward extensions of the tunica intima that prevent backflow of blood
name the 3 layers of the heart
endocardium, myocardium and epicardium
what is the endocardium made from
endothelium
basal lamina
thin layer of collagen fibres
layer of denser connective tissue
what area of the heart is made of loose connective tissue, small blood vessels and nerves, and branches of the impulse conducting system (Purkinje fibres)
subendocardium
what is the myocardium made of
bundles and layers of contractile cardiac muscle fibres
Individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rick network of capillaries
cardiac muscle cells have how many nuclei
single central nucleus (sometime 2)
what specialised structures are in cardiac muscle cells
intercalated discs
what is the external layer of the heart called
epicardium
what is the epicardium made of
-single layer of flattened epithelium called mesothelium
-basal lamina
-fibroelastic connective tissue and in some places adipose tissue
what is the pericardium
a sac of tough fibrocallagenous connective tissue
name the part of the pericardium that is made up of a layer of simple squamous epithelium (mesothelium), basal lamina and connective tissue
serous pericardium
what are the 2 types of serous pericardium
visceral and parietal
visceral serous pericardium covers where?
surface of the heart
what is the space between the visceral and parietal serous pericardium
pericardial cavity
what does the pericardial cavity contain
small amount (15-50ml) of pericardial fluid
what does the pericardial fluid aid?
lubrication for heart movement
what is the fibrous ‘skeleton’ of the heart and valves made of
thick bands of fibrous connective tissue around the valves and between the atria and ventricles
what does the fibrous ‘skeleton’ do
the fibrous connective tissue supports the valves and provides attachment for the cardiac muscle fibres
A core of dense connective tissue is called what
A core of dense connective tissue, called the lamina fibrosa, that is in continuity with the fibrous skeleton.
The leaflets of the valves separating the atria from the ventricles (the mitral and tricuspid) are anchored to …………..in the wall of the ventricle by collagenous strands called the chordae tendineae, which merge with the lamina fibrosa.
papillary muscles
leaflets of the mitral and tricuspid valves are anchored to papillary muscles in the wall of the ventricle by collagenous strands called the ……………….., which merge with the lamina fibrosa.
chordae tendineae
leaflets of the mitral and tricuspid valves are anchored to papillary muscles in the wall of the ventricle by collagenous strands called the chordae tendineae, which merge with the …………
lamina fibrosa.
what type of blood vessels are in valves
none - there are no blood vessels in valves
what is at the core of a heart valves
lamina fibrosa
The lamina fibrosa is the core of a heart valve and is ‘………… …………’ connective tissue that is continuous with the fibrous skeleton of the hear. What kind of connective tissue is described here?
dense irregular
name the 3 types of cardiac muscle cells:
contractile
pacemaker
conducting
