General anatomy of cardiovascular system

Cardiovascular system:
It is a transport system that carries blood and lymph to and from the tissues
of the body

Types of circulation –

Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart.

Left ventricle of heart—-artery – capillary—venule – vein — right atrium of heart—right ventricle — pulmonary artery (carry deoxygenated blood )—lung — four pulmonary vein (carry oxygenated blood ) – left atrium—left ventricle

Pulmonary circulation: Pulmonary circulation is the portion of the cardiovascular system which carries deoxygenated blood away from the heart, to the lungs, and returns oxygenated (oxygen-rich) blood back to the heart.

Right ventricle — pulmonary artery (carry deoxygenated blood)—lung — four pulmonary vein (carry oxygenated blood ) – left atrium

Portal circulation: any part of the systemic circulation in which blood passage through two sets of capillary before draining to the heart;

types :

1. Arterial portal system , EX: renal portal system

Heart – artery –1^st set capillary (at renal glomeruli) –arteriole —2^nd set capillary(at capillary plexus, surrounding the proximal and distal convoluted of nephron ) –vein —heart,

2. Venous portal system : EX: hepatic portal system

Heart – artery –1^st set capillary (GIT) –vein —2^nd set capillary (liver) –vein —heart

Blood
vessels:
definition: they are close system of tubular passages which convey the blood
from the heart to the different parts of body and from body to heart

Functions of blood vessel:

They transport the blood for
nutrition, respiration and excretion of the waste products of the body
Termo regulation Classification of blood vessels
1. Arteries: three types of artery
  1. large (elastic) artery,
  2. medium (muscular) sized artery,
  3. small artery
2. Arterioles
3. Capillaries
4. Venules and veins SN: heart—elastic artery(aorta) —medium sized artery— small sized artery—arteriole—terminal arteriole—meta-arteriole – pre-capillary sphincter – capillary—venule –vein —heart   Generalized structure of blood vessels:
  From within outwards the artery presents three coats –
  1.     Tunica intima: is consists of –
  endothelium
  subendothelial connective tissue
  internal elastic lamina
  2.     Tunica media :it is the thickest layer in case artery
  This layer consist of —
  circumferentially arranged smooth muscle cells with
  elastic lamina and collagen fiber
  Tunica adventitia: it is the thickest layer in case vein,it is formed by connective tissue rich in collagen and elastic fiber

Artery : definition : they are thick walled tubes which convey the
blood from heart to the capillaries

Types of artery :1. Elastic/ large artery 2. muscular / medium sized
artey 3. small sized artery

Features of elastic artery

tunica intima

*endothelium with its basal lamina

*subendothelial
connective tissue is present (contain
smooth muscle, collagen and elastic fibres)

*an inconspicuous internal elastic membrane

( internal elastic membrane present but difficult to
visualized in histological slide due to large amount of elastic fibres present
in elastic artery)

large amount
of elastic lamellae and smooth muscle cells present in between the elastic lamella

Relatively thinner form by connective tissue rich in collagen & elastic fibres

Examples: Aorta/Pulmonary arteries Brachiocephalic arteries / Common carotid artery

Features of muscular artery

endothelium with its basal lamina

*subendothelial connective tissue is present

(contain smooth muscle, collagen and

elastic fibres) and

*Prominent internal elastic membrane

circumferentially arranged smooth muscle cells,

with little elastic, collagen and reticular fibers

Relatively thicker

form by connective tissue rich in collagen & elastic fibres ,

external elastic membrane separated it from the tunica media

Brachial artery, femoral artery, external carotid artery

Small
artery / Arterioles: they are the smallest divisions of the muscular
arteries possessing three coats. They successively form terminal arteriole and
meta-arterioles. Meta –arteriole terminate as capillary.

Topics	Small arteries	Arterioles
Tunica media	Up to eight layers	Only one or two layers
Internal elastic membrane	Present	May or may not present
Tunica adventitia	Thin, ill defined	Thin, ill defined

Pre-capillary sphincter: the slight thickening of the smooth muscle at
the junction of meta- arteriole and the origin of a capillary bed is called
the pre-capillary sphincter

Functions
of arterioles:

Regulate the amount
of blood entering into the capillaries (by pre-capillary sphincter)

They offer peripheral resistance and regulate systolic arterial pressure

Anastomoses between arteries

Actual : Arteries meet end to end. EX: Labial branches of two facial arteries

Potential : Anastomoses is occurred by terminal arterioles, It need sufficient time for dilatation , Sudden occlusion of main artery, this anastomoses is failed to nourish the affected part. Ex: coronary arteries

End artery: End arteries are those which do not form any pre-capillary anastomoses.

They are two types:

Functional end artery :contain insufficient pre-capillary anastomosis

Example: coronary arteries

True end artery:no pre-capillary anastomosis

Example: Central artery of retina

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