Circulatory system Flashcards
function of CVS
circulates blood throughout the body
CVS system contains?
the pumping organ Heart, and the complex network of blood vessels
types of blood vessels are
arteries, capillaries and venous
what are capillaries and its function?
capillaries are thin endothelial tubes that connect the arteriole portion of the circulation to venous side. they are arranged in the form of capillary bed that allows the exchange of O2, CO2 and nutrients.
the structure of capillaries?
the have simple squamous called endothelium
basement membrane
and scattered contractile cells called pericytes.
what are pericytes ?
pericytes are also known as mural cells are contractile cells that wrap around the endothelial cells of capillaries and postcapillary venule.
structure of pericytes?
elongated cells with cytoplasmic processes which partially surround the capillary wall.
location of pericytes?
they are present on the out surface of endothelial cells so they share a common basement membrane with them
function of pericytes
they have contractile ability, regulation of the blood flow through capillaries and postcapillary venules. they can also differentiate into, smooth muscle cells, endothelial and fibroblast
features of continuous capillaries
these capillaries have no intercellular gaps and are thus continuous without any discontinuities.
their basement membrane is continuous too.
and the lining endothelial cells have no fenestrations
junction present in continuous capillaries and how materials are transported ?
they have occluding junction and the materials are transported through transcytosis thats why u can see numerous vesicles in the endothelial cytoplasm
where are continous capillary found
skin, muscles, lungs, CNS
fenestrated capillaries are what
they are same as continuous capillary but have numerous pores on the lining endothelial cells
Which are spanned by a thun diaphragm made of proteoglycans
Structure of fenestrated capillary
they are have continuous basement membrane without any interruptions and it covers the pored on the outer surface
Junction present in fenestrated capillary
occluding junctions, no intercellular gap so the endothelial lining is continuous
Where are fenestrated capillaries oresent
places like the intestinal villi, renal glomeruli and endocrine glands
What are discontinuous capillaries
they have endothelial lining with large gaps and these capillaries have large diameter. They also have pores with no diaphragm covering
Their basement membrane is also discontinuous, not present on the location of intercellular gaps
What is the other name of discontinuous capillary and what is its function
its name is sinusoidal capillaries and its main function is movement of cell in the blood into the tissue and vice versa and max exchange of macromolecules
where are discontinuous capillaries are found?
these are found in liver spleens bone marrow and other endocrine glands
three layers of arteries, capillaries veins etc
tunica intima
tunica media
tunica adventitia
tunica intima
its the inner most layer made up of a layer of single endothelial cells
below basal lamina there is a loose connective tissue present called subendothelial layer
outer most layer has a fenestrated membrane which has elastin called inter elastic lamina
tunica media
middle layer
made up of smooth muscles, arranged in concentric layers
variable amount of collagen, elastic and reticular fibers and proteoglycans.
has external elastic lamina
tunica adventitia
outer most layer made up of collagenous and elastic fibers arranged longitudinal
has vasa vasorum
nervi vascularis - network of unmyelinated sympathetic nerve fibers supply the tunic media
what is the diameter of arterioles
0.3 mm
explain the 3 layers of arterioles
tunica intima - endothelium and thin layer of subendothelial layer containing small amount of elastic and reticular fibers
tunica media - small arterioles one of the two layers of muscle fibers are arranged as compared to 5 layers of smooth muscle fiber in large arterioles
tunica adventitia- its scanty and and a thin layer of collagenous and elastic fiber is present
arteriole function
is the distribution of blood to different capillaries by constriction and dilation. chief controller of systematic BP
medium sized arteries are also known as
muscular arteries or distributing arteries
why medium sized arteries are called muscular arteries
their tunic media is thick having at least 40 layers of concentrically arranged smooth muscles
names of muscular arteries
axillary, popliteal, femoral, brachial
function if muscular arteries
they distribute blood to most parts and organs of the body by dilation and constriction that’s why they are called distributing arteries
tunica intima of muscular arteries
it has all 3 layers, endothelial cells, subendothelial layer which has elastic and collagenous fibers and internal elastic lamina which is prominent makes fenestrated sheet of elastic and looks corrugated dye to post mortem contraction of smooth muscles making the elastic fiber to fold
tunica media of muscular arteries
tunica media is thick having atleast 40 layers of smooth muscles concentrically arranged.
between the smooth muscles it has elastic and reticular fibers. external elastic lamina is seen as an elastic fiber at the junction of media and adventitia
tunica adventitia of muscular fiber
it is thick made up of elastic and collagenous fibers arranged longitudinally, similar structure as media
large arteries
they have abundant elastin in their walls, that’s why they are called elastic artery. they also conducts blood from the heart to all parts of the body through media arteries so called CONDUCTING ARTERIES
tunica intima of elastic arteries
they are thick and the subendothelial layer contains collagenous and elastic fibers running longitunially. no internal elastic lamina prominently visible
tunica media of elastic arteries
consist of elastin, smooth muscles, collagenous fibers and ground substance containing glycoprotein and proteoglycan
the elastin occurs as fenestrated lamella arranged concentrically, spaces between fenestrated lamina has smooth muscle bundles arranged circularly
number of fenestrated lamina at 2 ages
40 at newborn
70 in adult aorta
increases with age
tunica adventitia of elastic artery
it contains collagenous and elastic fibers arranged longitudinally, comparatively thin and has fibroblast n macrophages
functions of elastic arteries
the abundant of elastin in its wall helps with the diastolic blood pressure, when the ventricles contract (systole) the elastic lamina expands and when they relax(diastole) they recoil maintain the BP
this allows them to maintain a constant supply of blood to arterioles and capillaries
venules are classified into
post capillary venules and muscular venules
post capillary venule diameter
15-20 micrometer
post capillary venule strcuture
they have endothelial cells which has intercellular gaps in between. they have pericytes covering the endothelial covering so called PERICYTIC VENULE
the pericytes and the endothelium shares the basement membrane. the pericyte and endothelial cells are joined by tight junctions or gap junctions
function of intercellular gaps in post capillary venules
the leukocytes and fluid emigrates from the blood into the tissue at the time of inflammation and allergic reactions
function of pericytes on the endo cells of post capi venules
contribute to the synthesis of membrane
other name for muscular vein and its characteristics
its also known as small veins
it has 2-3 layers of smooth muscles that represents tunica media and also a thin tunica adventitia is also prominent which has collagen fibers
middle sized veins
diameter is 1-10 mm
tunica intima has endothelium and sub endothelium layer having elastic and collagenous fiber
tunica media has smooth muscle fiber and collagen fibers also have fibroblast and elastic fiber
tunica adventitia is composed of collagenous fibers and some elastic fibers (longitudinal running)
large veins tunica intima
10 mm in diamter
tunica intima has endothelial and well developed subendothelial layer having collagen and elastic fiber, fibroblast and few smooth muscles
well defines internal elastic lamina
large veins tunica media
is not well defined it has smooth muscle fiber and collagen fiber running concentrically with elastic fiber and fibroblast
large veins tunica adventitia
well developed and thick has bundles of collagen fibers with elastic fibers and smooth muscle fibers
endocardium
- continous with tunica intima of blood vessels
- subendothelial layer has collagen fibers, elastic fibers and smooth muscle fibers
- subendocardial layer has veins, nerves and branches of impulse conducting system of heart
- joins the endocardium with myocardium
intercalated disk
the cardiac muscle cells are adjoining the adjacent cell by a darkly stained cross band called intercalated disk
intercalated disk has 3 special junctions called
fascia adherents, gap junctions and desmosomes
myocardium in atria and its directions
the myocardium in atria has 2 layers
- superficial layer runs on both the atria and run oblique or in transverse direction
- deep layer covers each atria separately and runs at right angels to the muscle fibers
in ventricles the macular bundles take origin from?
dense fibrous connective rings ( annuli fibrosi) surrounding the atrio- ventricular valve
direction of muscle cardiac muscle in ventrciles
2 layers
-superficial layer runs in spiral from the base till the apex
-deep layer runs in circular coarse in each apex
also they are S shaped when they pass from each ventricle to another thru ventricular septum
epicardium
made of simple squamous epithelium
has sub pericardial layer adjoin the epi with mayo, has veins fat
connnective tissue rich in elastic fibers
cardiac skeleton 3 main components
- annuli fibrosi
- septum membranaceum
- trigona fibrosa
annuli fibrosi
dense connective tissue ring present one at the atrioventricular valve and one at the aorta and pulmonary trunk
septum membranaceum
present at the upper part of interventricular septum
trigona fibrosa
joins the annuli fibrosi with each other
explain the joing of musculature of atria and ventricle
atria musculature is attached to the annuli fibrosi of surrounding the aortic and pulmonary valves
musculature of ventricles is attached to annuli fibrosi at the AV valve
luminal plasmella of endothelial cells has>
glycocalyx coat consisting of meshwork of proteoglycans and glycoproteins
anticoaglants present in endothelial cells
thrombodulin, tissue factor pathway inhibitor
antithrombogenic present in endothelial cells
prostacyclin, tissue plasminogen activor, antithrombin III and heparin
prothrombogenic agents
von Willebrand factor, plasminogen activator inhibator
vasoconstrictors
endothelin and angiotensin converting enzyme
vasodilators
nitric oxide and prostacyclin
what is released by endothelium for immune response
cytokines interleukin family (I 8 AND 6)
CELL ADHESION molecules adherins and selectins
collagen type released and proteins released by endothelial cells
collagen type IV and laminin
functions of endothelium
- selectively permeability barrier
- maintenance of smooth anticoagulant and antithrombic surface
- state of injury they release prothrombogenic agents
- regulates blood flow and tissue perforation
- regulates immune response
- oxidation of lipoprotein
lymph capillaries endothelium and basal lamina explain
single layer of endothelium with incomplete basal lamina .
what junctions lymph capillaries make
no occluding junctions they just overlap ( the endothelium)
transport of macromolecules are done by?
intercellular clefts which allows macromolecules to diffuse into the lumen from interstitial fluid
thin filaments present in lymph cappilaries
anchoring filaments composed of elastin
where the thin filaments in lymph capillaries present
between the basal lamina of the endothelium and surrounding tissue
what does the anchoring filaments do
maintain the patency of the intercellular clefts
back flow of lymph is prevented by
valvular mechanism
tunica intima of lymph vessels contain?
endothelial cells layer and collagenous and elastic fibers beneath
tunica media of lymph vessels contain?
circularly running smooth muscles and some elastic fibers b/w them
tunica adventitia of lymph vessels
thickest
has elastic and collagenous fibers running longitudnally
some smooth muscle fibers
