Structure Of Blood Vessels Flashcards
Mention contents of tunica intima
Endothelium
Sub-endothelial layer
Internal elastic lamina
The IEL seperates … from …., while EEL separates …. from…..
Tunica intima from media
Tunica media from adventitia
Mention contentsvof tunica media
Circularly arranges smooth muscles, interposed by: Elastic lamellae Reticular fibers Proteoglycan & glycoprortein External elastic lamina
Mention fibers present in tunica adventitia
Collagen type I & elastic fibers
Mention the type(s) of vessels of vasa vasorum
Arteriole, capillary, venules
Mention vessels in which vasa vasorum are more frequent
Medium & large sized vessels
Veins
GR: Large arteries are also called elastic & conducting
E, as they contain large amount if elastic lamina in their media
C, as they conduct blood away from the heart
Examples of large arteries
The aorta, pulmonary & subclavian artery
Mention the type of junction between endothelial cells of large arteries
Occluding junction
GR, The IEL is indistinguishable in large arteries
Since it merges with elastic lamina in the next layer
Mention layer forming main thickness of wall in large arteries
Tunica media
Mention composition of tunica adevntitia in large arteries
Relatively thin, formed of fibro-elastic CT containing type I collagen
Conatins numerous vasa vasorum, nerves & lymphatic vessels
GR: medium arteries are also called muscular & distributing
As they consist mainly of smooth muscle in their media & they control blood supply to different regions by contraction & relaxation of smooth muscles in their walls
Subendothelial CT layer of medium art contain ….
Smooth muscle fibers
Mention number of layers of smooth muscles in tunica media of medium art
Up to 40
Mention special features of subendothelial CT in coronaries
Contains fat droplets, monocytes & longitudinal SM, thickens with aging.
Describe composition of tunica media in coronaries
Inner longitudinal SM fibers
Outer circular SM fibers
Seperated by middle elastic lamina
Enumerate elastic laminae of coronary artery
3 (internal, middle, external)
Mention special features of basilar artery
- Has wide lumen & thin wall as vein
- Has well developed IEL as artery
- No elastic laminae in media
- Absent EEL
- Adventitia is as thick as media
Define atheroma
Infiltration of intima by fatty material which accumulate in macrophages & is accompanies by increased collagen deposition
Mention diameter of arterioles, post-capillary venules & collecting venules
A: 0.5 mm
PCV: 0.1 to 0.3 mm
CV: 0.3 to 0.5 mm
Mention structures which gradully disappear/diminish as arterioles dec in size
Thin IEL
Smooth muscles of tunica media
The smooth muscle fibers of tunica media in metarteriole are …..
Discontinuous
Name structures which control blood flow to capillary bed from metarteriole
Pre-capillary sphincters
Tunica media if arterioles has no ……
EEL
The wall of PC venules consists of …..&…..
Single layer of endothelium w/ BM
Pericytes enclosed by basal lamina
The wall of collecting venules consists of …..,….&….
Endothelial cells
Pericytes
Thin adventitia
Tunica media of arteriole has NO
EEL
Describe composition of muscular venules
Endothelium with basal lamina
Thin media formed of 2 or 3 layers of smooth muscles
Thin adventitia
What us the thickest coat in medium & large sized veins
Tunica adventitia
What is the function valves in veins?
Maintaining continuous flow of blood preventing return of blood back to venules
Large veins have diameter greater than ….., e.g ……..
Their function is …..
10 mm
IVC & SVC
Ensure continuous flow of blood back to the heart and prevent pooling by means of valves
Mention the special feature of tunica adventitia of large veins
Longitudinally disposed smooth muscle fibers at the inner part that strengthen the wall to prevent excessive distension
Describe composition of valves of veins
Formed of 2 seminlunar folds of tunica intima, consist of CT rich in elastic fibers, lined by endothelium on both sides.
Describe the intermediate segment in direct connection & the site of this AV anastomosis
Well developed media shows SM fibers richly innervated by autonomic nervous system
Site: tips of fingers & toes, nose, lips. Internal organs as stomach, intestine, liver & endocrine glands
CCC & site of glomus
CCC by connective tissue capsule, its arteriole has no IEL, richly innervated thick muscular wall and narrow lumen.
Present in finger pads, fingernail beds & ears.
Describe structure of blood capillaries
Single layer of endothelium resting on BM, pericytes enclosed in their own basal lamina which may fuse with that if endothelial cells.
The longitudinal axis of endothelial cells is parallel to …..
Direction of blood flow
Intermediate filament of endothelial cells are ….
Desmin & vimentin
Mention junctions between endothelial cells
Occluding & gap junctions
Write a short note on pericytes
Mesenchymal in origin
Pluripotent, undifferentiated cells can diff to SM cells, fibroblasts & endothelial cells. Contain actin, myosin & tropomyosin.
Describe structure & site of continuous type of endothelial cells
A continuous complete wall of endothelial cells joined by tight junctions, complete basement membrane, pericytes enclosed within basal lamina, numerous pinocytotic vesicles for transport of substances to and from capillaries.
Site: skeletal muscles, cerebral capillaries, CT, thymus.
Describe structure & site of fenestrated type of endothelial cells
Endothelial cells are joined by tight junction, has fenestrae closed by diaphragm, continuous basement membrane, pericytes, tissue fluid can pass through fenestrae.
Site: glomerulus of kidney, endocarine glands & intestinal tract.
Describe structure and site of sinusoids
Lumen is irregular has wide diameter up to 40 um, discontinuous wall of endothelial cells separated by wide inter-cellular gaps having multiple fenestrae with no diaphragm, has macrophages but no pericytes. The wall is supported by reticular fibers.
Bone marrow, liver, spleen.
GR: effect of aging on vessels
Due to inc secretion of collagen type I & III, changes in composition of elastin
Define atherosclerosis
Fatty plaque deposits in the wall of arteries leading to narrowing or complete block of the vessel’s walls.
Mention organs without lymphatics
CNS & bone marrow
Lymphatic endothelial cells are…… than those of BV
Larger
Name the structures which hold lymphatic capillaries open
Anchoring filaments
…… prevent backflow from lymphatic capillaries
Endothelial folds
Describe effect if diabetes mellitus on capillaries
Diffuse thickening of capillary basal laminae with concomitant decrease in metabolic exchange esp in kidney, retina & skin.
Large lymphatic vesssels are similar to veins but have ….. walls and ….. valves
Thinner
More numerous internal
Describe structure of thoracic & right lymphatic duct
Similar to large veins in structure, but smooth muscles in middle layer are longitudinally & circularly arranged. Its adventitia is thin with vasa vasorum and neural network
Describe function of lymphatic vessels
Major distributor of lymphocytes, antibodies and other immune components which are picked up from lymph nodes and other lymphoid tissue.
Define thoroughfare channel
Distal part of channel between arteriole and venule whose distal part is a metarteriole
