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ANATOMY & PHYSIOLOGY II BIO 212:

Dr. Lawrence G. Altman www.lawrencegaltman.com Some illustrations are courtesy of McGraw-Hill.

LAB:

Blood Vessels Histology

Review

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General Appearance in sectional view

Tunica Intima Endothelium Int. Elastic membrane

Tunica Media (constriction/dilation) Ext. Elastic Membrane

Tunica Externa (Tunica adventitia)

TYPICAL ARTERY

TYPICAL VEIN

Usually round; relatively thick wall

Usually flattened or collapsed;

relatively thin wall Usually smooth;

sometimes rippled during vessel constriction

smooth; semilunar valves

present absent

thick: smooth muscle (ANS)

& elastic fibers thin:

smooth muscle (ANS) & collagen fibers

present absent

support: fibrous connective (elastic & collagen)

thickest layer of veins

support: fibrous connective (elastic & collagen)

slightly thinner than media

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TUNICA  INTERNA  

INTERNAL  ELASTIC  MEMBRANE  

ENDOTHELIUM  

Tunica  Interna  Endothelium  Usually  smooth  may  be  rippled  due  to  vessel  constriction  Int.  Elastic  Membrane  present  

TYPICAL  ARTERY  

EXTERNAL  ELASTIC  MEMBRANE  

SMOOTH  MUSCLE  

Tunica  Media  thick:  smooth  muscle  and  elastic  fibers  Ext.  Elastic  Membrane  present  

TUNICA  EXTERNA  

Tunica  Externa  (Tunica  adventitia)  collagen  &  elastic  fibers  

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ELASTIC  ARTERY  (large-­‐sized;      i.e.  AORTA)  

Vasa  vasorum  

Adventitia  

Media  

elastin  staining  in  media  

BLOOD  VESSELS  that  SUPPLY  another  BLOOD  VESSEL!  

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MUSCULAR  ARTERY  

(medium-­‐sized;    i.e.  renal)  

Adventitia  Media  

INTERNAL  ELASTIC  MEMBRANE  (IEL)  

EXTERNAL  ELASTIC  MEMBRANE  

mostly  elastic  fibers  

endothelium  barely  visible  

yellow  =  smooth  muscle  

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TYPICAL  LARGE  

ARTERIOLE  

Notice  increasing  amount  of  smooth  

muscle  cells  in  media  here.  

M

A

Also  Note:  flattened  nuclei  Of  endothelium  

(simple  squamous)  

M A

RBCs

RBCs

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ENDOTHELIUM  

TUNICA  INTERNA  

Tunica  Interna  Endothelium  often  smooth  Int.  Elastic  Membrane  :  absent  

:

TYPICAL  VEIN  

TUNICA  EXTERNA  

Tunica  Externa    (Tunica  adventitia)  collagen  &  elastic  fibers,  smooth  muscle  

TUNICA  MEDIA  

SMOOTHMUSCLE  

Tunica  Media  thin:  smooth  muscle  and  collagen  fibers  Ext.  Elastic  Membrane:  absent  

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TYPICAL  VEIN  endothelium  only;  

 2-­‐3  muscle  cell  layers  in  media  LARGE  MUSCULAR  VEIN  Example:  renal  veins  

VEIN  VALVE  

12 Arteriole  and  Capillary  

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Capillary  Circulation   17

MICROCIRCULATION  

ARTERIOLE

VENULE

RBC  

RBC  

N  Capillary  X-­‐section  

P  =  pericyte    possible  contractile  function  

RBCs  

E  =  ENDOTHELIUM  

LONGITUDINAL  SECTION  

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CAPILLARIES  

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