Histology Flashcards
what are the roles of the cardiovascular system
Transport of oxygen and nutrients to the tissues.
Transport of CO2 and other metabolic waste from the tissues.
Temperature regulation.
Distribution of hormones and immune cells.
Reproductive function in males: penile erection.
what are the three layers of blood vessels
inner = tunica intima, middile = tunica media, outer = tunica adventitia
describe the tunica intima
single layer of squamous epithelial cells (endothelial) supported by a basal lamina and thin layer of connective tissue
what is a basal lamina
extracellular matrix on which epithelial sits (basement membrane)
describe the tunica media
predominantly smooth muscles, thickness varies
describe the tunica adventitia
supportive connecting tissue
what separates the tunica intima and the tunica media
layer of elastuc tissue called the internal elastic membrane
what separates the tunica media and the tunica adventitia
external elastic membrane
what are elastic arteries
largest arteries (e.g. aorta) as have many sheets of elastic fibres in their tunica media to provide elastic recoil
what does the recoil elastic arteries maintain
diastolic blood pressure
what are vasa vasorum
vessels of the vessel- supply nutrients to outpart of vessel that cannot obtain nutrients from the lumen
what is a lumen
inside of tubular structure
what happens to the composition of arteries as they become smaller
loose layers of smooth muscles
describe the composition of arterioles
one or two layers of smooth muscle in their tunica media with almost no tunica adventitia
describe the composition of capillaries
endothelial cells and a basal lamina (diameter of 4-8 micrometers)
what are pericytes
connective tissue with contractile properties local at intervals out basal lamina of capillaries
what are the three types of capillaries
continuous, fenestrated, sinusoidal/discontinuous
describe continuous capillaries
most common- found in muscle, connective tissue, lung, skin and nerves
describe fenestrated capillaries
have approx 50nm pore in wall. found in mucosa of the gut, endocrine glands, glomeruli of the kidney
describe sinusoidal or discontinuous capillaries
lack a basal lamina and have large gaps. found in liver, spleen and bone marrow
what is microvasculature
Small arterioles connect to a postcapillary venule through a network made up of metarterioles, thoroughfare channels and capillaries.
what are precapillary sphincters
smooth muscle rings at the beginning of the capillary to help control flow through the network
where do capillary networks drain into
post capillary venules
describe post capillary venules
endothelial cell-lined and contain a thin layer of connective tissue and occasional pericytes
what happens at post capillary venules
important sites for exchange
when do post capillaries venules become ‘venules’
once vessel begin to acquire intermittent smooth muscle cells in a tunica media layer
describe the tunica adventitia of the largest veins
thick with incorporated bundles of longitudinally oriented smooth muscle
why do veins contain most of the blood in the body
as are flexible and can accommodate the expansion
what are the valves in veins made of
inward extensions of the tunica intima
how do you histologically differentiate an artery and vein
thickness of tunica media artery thick
what are the three layers of the heart
endocardium (inner), myocardium (middle), epicardium (outer)
what are the two layers of the serous pericardium
visceral and parietal
what are the layers surrounding the epicardium
epicardium-visceral layer of serous pericardium-
pericardial cavity- parietal layer of serous pericardium- fibrous pericardium- adipose tissue
what does endoCARDIUM line
entire inner surface of the heart including the valves
describe the structure of the endocardium
endothelium, basal lamina, thin layer of collagen fibres, layer of denser connective tissue
what is a subendocardium
in some areas of heart- loose connective tissue containing small blood vessels and nerves and the branches of the impulse conducting system.
what is backing the endothelial layer of the endocardium
fibrous tissue
describe the structure of the myocardium
thick middle layer,
bundles and layers of contractile cardiac muscle fibres,
individual muscle fibres are surrounded by delicate, collagenous connective tissue with a rich network of capillaries
(cardiac muscle cells in connective matrix)
describe the myocardium structure
single central nucleus cardiac muscle cells.
intercalated discs passing across the fibres at regular intervals
what is the purpose of the intercalated discs passing across the muscle fibres in the myocardium
acts to attach cells but allows spread of electrical activity- creates extensive network that stops intracellular junction ripping apart when the cells contract
what allows the spread of electrical activity between cells
gap junctions
describe the epicardium
on the surface of the heart
a single layer of flattened epithelium called mesothelium
basal lamina
fibroelastic connective tissue and (in some places) adipose tissue
where are the coronary arteries and what does their placement allow
on surface in adipose tissue (under connective tissue and mesothelium) allows easy access- bypass
what is the mesothelium
the simple squamous epithelium that lines the pleurae, peritoneum, and pericardium
describe the fibrous pericardium
sac of tough fibrocollagenous connective tissue
describe the serous pericardium
layer of simple squamous epithelium (mesothelium), backed by a basal lamina and connective tissue
what does the serous pericardium line
the inner surface of the fibrous pericardium (parietal) and covers the surface of the heart (visceral)
what separates the two mesothelial layers of the serous pericardium
pericardial cavity which contains a small amount of pericardial fluid
describe the fibrous skeleton of the heart
formed by thick bands of fibrous connective tissue around the heart valves between the atria and ventricles
what is the role of the fibrous skeleton of the heart
supports the valves, but also provides the attachments for the cardiac muscle fibres and acts as electrical isolator between atria and ventricles
are there blood vessels in the heart valves
no
describe the structure of the heart valves
Have an outer endothelial layer with basal lamina.
Layer of collagen and elastin fibres.
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 papillary muscles in the wall of the ventricle by collagenous strands called the chordae tendineae, which merge with the lamina fibrosa.
describe the lamina fibrosa
the core of a heart valve and is dense irregular connective tissue that is continuous with the fibrous skeleton of the heart.
what covers the heart valve on both sides
endothelium
what are the three types of cardiac muscle cell
contractile, pacemaker and conducting
describe pacemaker cells
pale because of organelles within them
embedded in extensive matrix of connective tissue
fer myofibrils, little glycogen
how does electrical signals travel through the skeleton
tunnel in skeleton for AV bundle
describe purkinje cells
larger than normal cells,
They have, abundant glycogen, no T-tubules, no intercalated discs and sparse actin and myosin filaments, which tend to be found at the periphery of the cells.
found in the subendocardial layer just deep to the endocardium, they appear pale, and often exhibit a very pale/clear centre.
where in the body are lymphatic vessels missing
brain and bone
what is the role of the lymph system
system of relatively thin walled vessels that drain excess interstitial fluid (lymph) into the blood stream
what is the role of lymph nodes
immunological surveilance
describe lymphatic vessels
no central pump, but smooth muscle in walls, hydrostatic pressure in the tissue and compression of the vessels by voluntary muscle, combined with valves in the vessels, produces flow.
