CIRCULATORY SYSTEM
DEFINITION
< System which transport material like nutrient, gases,
hormone etc. to the various parts of the body and remove waste materials from
the body cells known as circulatory system.
TYPES OF CIRCULATORY SYSTEM
< Whole circulnatory system develops from mesoderm but
endocardium of heart and endothelium of blood vessels & lymph vessels
develops from endoderm.
< In man circulatory system
include two types-
(1) Blood Circulatory System
In this, circulatory fluid is blood. This system includes
blood, blood vessels, and heart. This is found in higher invertebrates
(2) Lymphatic system
In this, circulatory fluid is lymph. This system includes
lymph, lymphoid tissue and lymph vessels. It is found in higher vertebrantes.
BLOOD CIRCULATORY SYSTEM
< It is closed type, blood
circulate in blood vessels and transport to different organs.
< Angiology- Study of circulatory system.
< Father of Angiology - William Harvey
< William Harvey
wrote a book named "Motu- dicordis"
< William Harvey firstly
described that heart pumps blood.
< Blood flow in a close
channel veins have valve.
< Fabricious report presence of valve in vein firstly.
< Marcello- malpighi discovered Capillary Network. He told "the
artery and veins are connected by capillary"
TYPES OF BLOOD CIRCULATORY SYSTEM
Blood vascular system is of two type-
(1) Open Blood Vascular System
< Blood present in coelomic
channel and sinusoids.
< Blood in general refer as
haemolymph.
< Tissues are directly
connected with blood.
e.g. Arhropods, Echinodermata, Mollusca. (excepts
cephalopoda)
(2) Close Blood Vascular System
< Blood flows in blood
vessels.
< Blood have not direct
contact with tissue.
e.g.: annelida, some mollusca, Hemichordate and chordata.
< Following parts present in
blood circulatory system of higher animals.
(1) Heart (2) Blood
vessels (3) Blood
HEART
< Mesodermal, pinkish colour,
Conical, hollow and muscular organ.
< Heart
present in mediastinal space in between both lungs. It is towards ventral side
of the body. It lies between 5th and 6th ribs.
< It is triangular. Its
anterior end is broad and slightly turn towards right side.
< Posterior narrow end turns
towards left side.
< Heart is covered by two
layers.
Outer fiberous pericardium---->Pericardium Parietal layer
Inner serous pericardium------->Visceral layer
< The pericardium layer is
composed of white fiberous connective issue.
< A narrow cavity is present between parietal &
visceral called pericardial cavity. A fluid is present in this cavity, called
pericardial fluid.
< The amount of pericardial
fluid approximate is 10 to 15 ml.
< Pericardial cavity is a
true coelom.
< Size of human heart is 12 x
9 x 6 cm.
< Weight of human heart is
300gm. in male while is 250 gm in female.
< Heart forms 1/130 part of
infant body.
< Heart forms 1/300 part of
adult body.
< Left ventricle of heart is
known as "Apex" of Heart.
FUNCTION OF PERICARDIAL FLUID:
Provide
most the heart
Protect
from external shock.
Prevent
pericardial membrane to stick together.
Prevent
from harmful effect of friction during heartbeat.
Prevent
infection of heart.
Helpful
in expansion of heart during pulsation but prevent after a limit.
< Invertebrate and
protochordate have single chambered heart.
< Lung fishes have two
auricles and single ventricle.
< Other Fishes have two
chambered heart. It is called venous heart in which always fill deoxygenated
blood.
< Reptile have four chambered
heart. It have two clear auricle but two ventricle have no clear separation.
--->Crocodile have four chambered heart.
< All birds and mammals have
complete four chamber.
< Tubular heart present in
arthropods.
< Pulsating heart present in
Annelids and mollusca.
< Man has four chambered
heart.
EXTERNAL STRUCTURE OF HEART
< Upper two are auricles
while lower two are ventricles.
(1) AURICLE
< Auricle part is broad and dark in colour. Its wall is
thin. Two auricle are separated by a inter auricular septum.
< Right auricle is comparatively larger than left one.
< Each auricle at its posterior side have a prominence
which is termed as auricular appendix.
It covers some parts of its side ventricle.
< A longitudinal deperression
present between auricles known as interauriclular
sulcus.
(2) VENTRICLE
< These are broad, light
coloured and thick walled. Both ventricles are separated by interventricular septum.
< Left ventricle is
relatively thicker than right one because left ventricle pump blood into whole
body.
< Pure blood comes from lungs
into left auricle by pulmonary vein.
< Due to absence of
sinus venosus and conus arteriosus, both pulmonary arch and carotico
systemic arch comes out separately from heart.
< Pulmonary arch originate
from right ventricle and carotico systematic arch from left ventricle.
< A longitudinal deperression
present between ventricle known as interventricular
sulcus.
< A transverse deperression present between auricle and
ventricle known as interauriculo
ventricular
sulcus or coronary sulcus.
INTERNAL STRUCTURE OF HEART
< Heart walls are made up of cardiac muscles, These are
branched, striated, involuntary and multinuclcate.
< Heart
muscles have following three covering-
(i) Epircardium : Composed of simple squamous epithelium(Mesodermal)
(ii) Myocardium : Composed of
cardiac muscle.
(iii) Endocardium
: Composed of simple squamous epithelium. (Endodermal)
< Myocardium thickest and
endocardium thinnest layer
< Myocardium of left
ventricle is three time thicker than Right ventricle
< Heart muscles work
continuously. Lactic acid does not form, thus cardiac muscles never show
fatigue.
< Left ventricle have thicker and muscular wall than right
venticle. So that left ventricle have smaller lumen (Round and oval shaped).
< Both auricle are separated by a myomembranous partition
called inter auricular septum. During foetal stage, at the place of this
septem, there are present septum primum
and secondum.
< Inter auricular septum have a pit like structure at
posterior end towards right side, called
fossa
ovalis. Left depression on posterior part of interauricular septum is known
as fossa
lanuta. In embryonic stage
this part bear a foramen as called foramen
ovalis.
< From the opening of inferior vena cava upto foramen
ovale, there is a flap called eustachian flap which prevents the blood in the
foetal heart go to lungs, because in foetal life, lungs are not functional
purification of blood is done by placenta.
< In embryonic phase blood of both right and left ventricle
is in direct contact through foramen
ovalis because lungs are non-functional. In adult stage foramen is closed.
< Both right auricle and ventricle are connected by formen
ovalis in embryonic condition because lungs are non functional. After
maturation this foraman will be closed and a pit formed here.
< If there is no closure of foramen ovales after birth in
there is mixing of blood which gives bluish appearence of body. This disorder
is known as "Cyanosis" and this type of body is known as "Blue baby".
< Many small striated prominences are present on auricular
wall, called as musculi pectinati or
trabeculae pectinati.
< Two separate venacavae
opens into right auricle, One superior, one inferior.
< Eustachian valve present opening of inferior vannacava.
< Near the opening of
superior venacava, on heart wall, a sinus is open, called coronary sinus.
< At the coronary sinus Thebesian valve is present.
< Pulmonary vein opens into
left auricle which drive pure blood from lung.
< In man and cat, right
superior venacava is absent. Only left superior venacava is present.
< Each auricle opens into
ventricle through a large auriculo-ventricular valve.
< Right valve is made up of three flaps, called as tricuspid valve while left valve have
only
two folds, called bicuspid valve. These valves prevent backflow of
the blood from ventricle to
auricle.
< Bicuspid valve is also
known as mitral valve due to their
cap like shape.
< Folds of both valves are connected with muscular column, Columnae carnae and musculi
papillaris by tendous called as
chorda tendinae.
< Columnae carnae are small
folds while the musculi
papillaris/papilaris muscles are large size fold.
< Three musculi papillaris present in left ventricle.
< Two musculi papillaris present in right ventricle.
< Carotico systemic arch comes out from left ventricle. At
the base it have three semilunar
valve
which prevent backflow.
< Similarly, Pulmonary arch comes out from right ventricle,
It drive impure blood to lungs. It
also have three semilunar valve at the base.
< Both arches from cross
after originating. At cross they joint together with ligamentum arteriosum.
< In embryonic phase "ductus
arteriosus" or ductus botalli is present here.
< Pure blood comes out from
lungs and enters into left auricle through to pair pulmonary veins.
< One pair pulmonary veins
are present in heart of rabbit.
< Heart wall have some
connective tissue rings. These support heart wall and prevent excessive
expansion of heart, It also provide space for attachment to heart
muscle. These are also known as "heart
skeleton."
