the circulatory systemthe circulatory system
TRANSCRIPT
Basic Structure of CirculatoryBasic Structure of Circulatory System
• Tunica intima– Endothelium supported by basement membraneEndothelium supported by basement membrane
and delicate collagenous tissue.• Tunica mediaTunica media
– Muscle and CT• Tunica adventitia• Tunica adventitia
– CT
Layers of ArteryA mediumsized
lmuscularartery,showing its layers.
The usual histologic preparations cause the layers to appear thicker than those shown here; the drawing is actually similar to the in vivo architecture of the vessel. At the moment of death, the artery experiences c ec u e o e vesse . e o e o de , e e y e pe e cesan intense contraction; consequently, the lumen is reduced, the internal elastic membrane undulates, and the muscular tunica thickens.
Types of Vessels
• Elastic artery• Muscular arteryMuscular artery• Arteriole
C ill• Capillary• Muscular venule, small vein• Vein• Muscular veinMuscular vein
Layers of Aorta
• Tunica intima– Endothelium– Collagenous fibers, elastic fibers & elastin sheets
• Tunica media– Extremely elastic (sheets of elastin), smooth muscle
• Tunica adventitia– Collagenous, elastic fibers
Muscular Artery
• Tunica intima– Endothelium
i ll fib h l– Fine collagenous fibers, smooth muscle– Internal elastic lamina clearly evident
• Tunica media• Tunica media– Smooth muscle– Collagenous, reticular, elastic fibers – External elastic lamina clearly evident
• Tunica adventitia– Thick collagenous, elastic tissue
Arteriole
• Tunica intima– Endothelium– Some CT– Internal elastic lamina may be present
• Tunica media• Tunica media– Muscle layer several layers thick– External elastic lamina may be present
• Tunica adventitia– Collagenous, elastic CT as thick as tunica media
Veins
• Tunica intima– Endothelium– Scant CT
• Tunica media– Thin muscle layer– Collagen, elastic fibers
• Tunica adventitia– Bulk of vessel wall
HEART
• Epicardium– (Tunica adventitia)(Tunica adventitia)
• Myocardium(Tunica media)– (Tunica media)
• Endocardium( i i i )– (Tunica intima)
• Surrounded by pericardium
Myocardium and EndocardiumEndoEndo
Myo
Endocardium consists of endothelium which is supported by a pp ydelicate layer of collagenous tissue beneath which lies a fibro-elastic layer.
Epicardium
Mesolthelium (single layer of epithelium) surrounds think layer of fibro elastic tissue Adipose tissue connects epicardium tofibro-elastic tissue. Adipose tissue connects epicardium to Myocardium.
ARTERIOLESARTERIOLES
Lumen: < 0.3mm dia
Thin tunica intimaEndothelium
i l ll iLittle collagenous support tissueThin IEL
Tunica mediaTunica media
T i d titiTunica adventitia
CAPILLARIESCAPILLARIES
• Diameter 3 - 40 um• EndotheliumEndothelium
– ContinuousDiscontinuous– Discontinuous
– Fenestrated
VEINS
Tunica intimaLittl th d th liLittle more than endothelium
Tunica mediaThin layer of smooth muscle
Tunica adventitiaThickest layer