Histology Of Circulatory Histology Of Circulatory SystemSystem

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Dr. Mohammed Ahamed AbuelnorDr. Mohammed Ahamed Abuelnor

The Functions of the circulatory The Functions of the circulatory SystemSystem

1- Transport of the oxygen and nutrient 1- Transport of the oxygen and nutrient substance to the tissue.substance to the tissue.

2- Transport of the carbon dioxide and wast 2- Transport of the carbon dioxide and wast product from the tissuesproduct from the tissues

3- regulation of the body temperature3- regulation of the body temperature 4- Transport of hormones and large molecules 4- Transport of hormones and large molecules

The parts of the circulatory systemThe parts of the circulatory system

TheThe BloodBlood vascularvascular systemsystem: which is : which is responsible for the circulation of the bloodresponsible for the circulation of the blood

TheThe lymphlymph vascularvascular systemsystem: responsible for : responsible for circulation of the lymph circulation of the lymph

The blood vascular SystemThe blood vascular System

DefinitionDefinition: It is system of vessels through : It is system of vessels through which the blood passes to the tissues by the which the blood passes to the tissues by the continuous contraction of the heartcontinuous contraction of the heart

The blood vascular system formed of:The blood vascular system formed of:

- The heart- The heart

- The arteries- The arteries

- The veins- The veins

- The capillaries - The capillaries

The Basic Layers of the circulatory The Basic Layers of the circulatory systemsystem

The inner layer called the tunica intimaThe inner layer called the tunica intima The middle layer called the tunica media The middle layer called the tunica media The outer layer called the tunica adventitiaThe outer layer called the tunica adventitia

The HeartThe Heart

DefinitionDefinition: It is muscular organ which is : It is muscular organ which is located at the middle of the chest. It is function located at the middle of the chest. It is function pumping of the bloodpumping of the blood

It is formed of four chambers, tow atria and tow It is formed of four chambers, tow atria and tow ventricles they communicate with ventricles they communicate with atrioventricular orificeatrioventricular orifice

The right side of the heart carry non oxygenated The right side of the heart carry non oxygenated blood and the left carry oxygenated blood and the left carry oxygenated

The Histological structures of the The Histological structures of the heartheart

TheThe tunicatunica intimaintima: It is the inner layer called : It is the inner layer called the endocardium it formed of simple squamus the endocardium it formed of simple squamus epithelium it separated from the tunica media by epithelium it separated from the tunica media by elastic fibers elastic fibers

TheThe TunicaTunica mediamedia: called the myocardium. It : called the myocardium. It is muscular layer formed of cardiac muscle. It is muscular layer formed of cardiac muscle. It thick in the ventriclesthick in the ventricles

TheThe tunicatunica adventitiaadventitia: called the epicardium : called the epicardium formed of mesothelium formed of mesothelium

The HeartThe Heart

The conducting system of the heartThe conducting system of the heart

DefinitionDefinition: It is formed modification of areas in : It is formed modification of areas in the myocardium of the heart to regulate the the myocardium of the heart to regulate the contraction of the atria and ventriclescontraction of the atria and ventricles

The conducting system formed of Sino atrial The conducting system formed of Sino atrial node (S.A.N) and atrioventricular node (A.V.N) node (S.A.N) and atrioventricular node (A.V.N) and atrio ventricular bundle (A.V.B) and atrio ventricular bundle (A.V.B)

The arterial systemThe arterial system

DefinitionDefinition: The arterial system carry the : The arterial system carry the oxygenated blood from the heart to the oxygenated blood from the heart to the capillariescapillaries

According to the size of the arteries there are According to the size of the arteries there are three types :three types :

- Large arteries ( elastic arteries) Large arteries ( elastic arteries) - Medium arteries (muscular arteries)Medium arteries (muscular arteries)- Small arteries (arterioles) Small arteries (arterioles)

The histological structure of the The histological structure of the large arterieslarge arteries

It is formed of the three basic layers:It is formed of the three basic layers: TheThe tunicatunica intimaintima: formed of simple squamuse : formed of simple squamuse

epithelium called the endothelium rest on epithelium called the endothelium rest on basement membrane of elastic fibers basement membrane of elastic fibers

TunicaTunica mediamedia: It is thick layer formed of : It is thick layer formed of smooth muscle with elastic fibers distributed smooth muscle with elastic fibers distributed between itbetween it

TunicaTunica adventitiaadventitia: formed of collagen fibers : formed of collagen fibers and small vessels called vasa vasorum and small vessels called vasa vasorum

Large artery (cross sectionLarge artery (cross section((

The histological structure medium The histological structure medium arteryartery

TunicaTunica intimaintima: formed of endothelium separated : formed of endothelium separated from the tunica media by the internal elastic layerfrom the tunica media by the internal elastic layer

tunicatunica mediamedia: It is muscular layer of smooth muscle it : It is muscular layer of smooth muscle it is thin than of the large arteries separated from the is thin than of the large arteries separated from the adventitia by the external elastic layeradventitia by the external elastic layer

TunicaTunica adventitiaadventitia: formed of collagenous fibers : formed of collagenous fibers support the artery with surrounded structure support the artery with surrounded structure

Medium artery Medium artery (longitudinal section(longitudinal section((

The histological structure of small The histological structure of small arteriesarteries

It is the terminal branches it is diameter less than 0,3 It is the terminal branches it is diameter less than 0,3 mm. mm.

TunicaTunica intimaintima: it is thin and formed of endothelium : it is thin and formed of endothelium TunicaTunica mediamedia: formed of smooth muscle arranged : formed of smooth muscle arranged

into six layersinto six layers TunicaTunica adventitiaadventitia: formed of collagen fibers fused : formed of collagen fibers fused

with the surrounded structurewith the surrounded structure The flow of the blood through the capillaries is The flow of the blood through the capillaries is

regulated mainly by this arteriesregulated mainly by this arteries

Small artery (cross sectionSmall artery (cross section((

The capillariesThe capillaries

DefinitionDefinition: It is an inter connected thin walled : It is an inter connected thin walled vessels through which the material exchange vessels through which the material exchange between the blood and the tissuebetween the blood and the tissue

The blood reach the capillaries through small The blood reach the capillaries through small arteries called pre capillary and leave it through arteries called pre capillary and leave it through small venules called post venules small venules called post venules

Histological structure of capillariesHistological structure of capillaries

The wall of the capillaries is thin and formed of layer of The wall of the capillaries is thin and formed of layer of endothelium of flat cells rest on basement membraneendothelium of flat cells rest on basement membrane

The capillaries formed of many types according to the The capillaries formed of many types according to the following:following:

The diameter of the capillaries: the are tow types. The diameter of the capillaries: the are tow types. SmallSmall capillariescapillaries which formed most of the body capillaries. which formed most of the body capillaries. LargeLarge capillariescapillaries has large diameter and called has large diameter and called sinusoid it found in the liver, kidney and bone marrow. sinusoid it found in the liver, kidney and bone marrow.

Type of capillariesType of capillaries According to the endothelium lining the capillaries: the According to the endothelium lining the capillaries: the

are three type of capillariesare three type of capillaries A- A- continuouscontinuous capillariescapillaries: there is no opening : there is no opening

between the endothelium cells this type formed the between the endothelium cells this type formed the most of the body capillariesmost of the body capillaries

B- B- fenestratedfenestrated capillariescapillaries: in this type there are : in this type there are opening between the endothelium cellsopening between the endothelium cells

C- C- discontinuousdiscontinuous capillariescapillaries: part of the capillaries : part of the capillaries formed by surrounding tissue found in the liver formed by surrounding tissue found in the liver

Type of capillariesType of capillaries

According to the arteriovenouse shunt: some According to the arteriovenouse shunt: some capillaries has shunt to rapid the process of capillaries has shunt to rapid the process of exchange of material between the blood and the exchange of material between the blood and the tissuestissues

Formation of capillariesFormation of capillaries

Continuous capillariesContinuous capillaries

Fenestrated capillariesFenestrated capillaries

The venous systemThe venous system

The venous system carry the non oxygenated The venous system carry the non oxygenated blood to the heart the veins collected to drainage blood to the heart the veins collected to drainage at the heartat the heart

The blood passes in the venous system by the The blood passes in the venous system by the external pressure due to muscle contractions, external pressure due to muscle contractions, respiration and the valves found in the veins respiration and the valves found in the veins

Histological structures of the small Histological structures of the small veinsveins

- - tunicatunica intimaintima: formed of endothelium and : formed of endothelium and not contain elastic fibersnot contain elastic fibers

- - tunicatunica mediamedia: formed of tow layers of smooth : formed of tow layers of smooth muscle and it is very thinmuscle and it is very thin

- - tunicatunica adventitiaadventitia: it is formed of collagen : it is formed of collagen fibers connected the vein with the surrounded fibers connected the vein with the surrounded structures structures

Small vein (cross sectionSmall vein (cross section((

Histological structures of the Histological structures of the medium veinsmedium veins

The medium veins formed by the collection of The medium veins formed by the collection of the small veins and drainage into the large veinsthe small veins and drainage into the large veins

The histological structure is similar to the small The histological structure is similar to the small veins but the tunica media is thicker and contain veins but the tunica media is thicker and contain elastic fiberselastic fibers

The medium veinThe medium vein

The large veinThe large vein

This like the femoral vein, renal vein the formed This like the femoral vein, renal vein the formed by the collection of the medium veinby the collection of the medium vein

It is structure similar to the medium vein but the It is structure similar to the medium vein but the tunica media very thick and contain collagen tunica media very thick and contain collagen fibers and the internal elastic layer may present fibers and the internal elastic layer may present

Large vein (longitudinal sectionLarge vein (longitudinal section((