2.2 Vessel Structure Flashcards
Histology of typical blood vessel. Three layers?
Tunica externa, media, interna.
More obvious in arteries than veins
Major types of vessel?
Art, vein, capp, lymph
The layers. Outside to in?
Nerves, bv, adventitia, external elastic layer, tunica media, internal elastic layer, sub-endothelial ct, tunica interna: endothelial layer, basal lamina
Arteries to arterioles. Classification based on morphology.
SM proportion increases. Elastic decreases.
Layers of sm decreases
Aorta major branches
Subclavian, common carotid, brachiocephalic, common iliac, pulmonary
Size of artery wall near heart? And why?
Thick.
Preserve pressure - recoil during diastole - maintain arteriole pressure
Elastic arteries….
Not conc in external and internal lamina
Lp - elastic fibres and mod. Sm cells -> myointimal -> age accumulate
Lipids
Muscular arteries
Less elastic (int ext lamina), higher sm, vasoconstriction
Difference between muscular and small muscular artery?
20-30 layers - concentric - sm
3-10 concentric layers of SM
Resistance vessels
Control blood - organs
Partial contractive
2-5 layers of sm cells
Major determinants of systemic blood pressure
Ateriole (5)
Thicker wall rel lumen. Int ext elastic lamina
T interna - no subendothelial tossue
T media - thickest 1-2 sm layer
T externa - fibroelastic
5 types of arterial anastomoses
Inosculation (direct end to end or multiple arcades)
Capillary network
Convergence
Branches
Capillary network.
Microvascular bed (3) outline components.
What are preferential channels? And example?
How blood bypass capillary network?
Function of pre-capillary sphincters?
How is blood flow regulated?
Terminal arteriole, capillary bed, post capp venule
- continuous blood flow (larger capillaries - met-arteriole)
- av shunt or anastomoses
- contract relax - control blood flow into bed
- vasomotor nerves, chemical changes
Av shunts - where found? (4) Structure, difference compared to precapp sphincter, important in?
Fingertips, nose, lips, corpora cavernosa (penis)
Rich bv, nerves. Capsule, thick sm layer.
Opposite to sphincter. Contraction - blood into bed.
Thermoregulation
Capillaries ?
Single layer endothelial, one rbc pass, pericytes.
Function: gas exchange, hormone, ions, nutrients, wastes etc
Examples of Tissues where not rich capillary supply? (5)
Types of capillaries (3) where each found (3 each)
Tendons, ligaments, cornea, lens, epithelial tissue
Continuous: brain, lung, muscle
fenestrated intestine kidney endocrine glands, si, ciliary process of eye
discontinuous: liver spleen bone marrow, some endo glands, lymphoid tissue
Continous capp?
PP L O PP
Lack pores, impermeable, uninterrupted lining, occluding junctions, pinocytotic vesicles, pericytes.
Blood (brain, testis, thymus barrier)
Fenestrated capp?
80-100nm. Dynamic. basement membrane continuous across fenestrations.
Where? Kidney, si, cillary process of eye, endocrine glands
Where filtration or absorption occur
Discontinuous/sinusoidal capp
Large lumen, permeable.
No diaphragm, discontinuous basal lamina
Liver, spleen, some endocrine glands, lymphoid tissue, bone amrrow
Properties of endothelium?
Selectively permeable barrier - diffusion, active transport, pinocytosis, receptor mediated endocytosis
Nonthrombogenic barrier - secretion : anticoagulants, anti/pro thrombogenic agents
Mod blood flow, vascular resistance - secretion : vaso-constrictors/dilators
Reg. cell growth - secret. Growth stim / inhibiting factors
Immune response - reg. : leukocyte migration, immune functions
Extracellular matrix - syn basal lamina, glycocalyx
Lipoprotein met - free rad production
Veins (7). Where origin. Function. Pressure. Structure. Extra (2)
Origin - capp network Valves (semilunar/sparrows nest) - tunica intima, fibroelastic tissue (veins >2mm) Lower pressure than arteries Thinner, less elastic tissue Several anastomosis Capacitance and reservoir vessel
Blood volume %. Veins. Lungs. Heart. Arteries. Capillaries.
65 10 10 10 5
Veins types
Small - post capp. Mucular. Collecting venules
Medium
Large
Veins structure
Less well defined tunicas
adventitia greater than media
Less elastic tissue
Elastic membranes poorly developed.
Veins categorised based on movement (2) and different areas in respect
Receptive - head, neck, curtaneous, upper limb
Propulsive - thicker, more sm
Lower limbs, inferior vena cava, portal, splenic, superior mesenteric, external iliac, renal, arzygos
Post capillary venules. (6)
Main site of?
Diammeter etc?
Smallest. Porous endothelium. No sm.
Allow fluids, wbc.
Main site of vasoactive agents - inflammation, allergic reactions
10-50um
Example of vasoactive agent?
Histamine
Muscular venules amd its diammeter
Few sm layers.
80-100um
Where are high endothelial venules found?
Differences in endo?
Lymph nodes.
T cells enter lymph nodes via HEV(lymphatic vessels)
All secondary lymphoid organs except spleen
Endo - plump than squamous
Medium sized vein. And thickest layer - what is it composed of?
Tunica adventitia - collagen fibres - longitudinal.
Large vein. Tunica media and Tunica adventitia arranged?
Narrow tunica media - small amounts of sm - circular
Adventitia - Longitudinal SM + collagen fibres
Elastic fibres scattered throughout
Lymphatic vessels? (5)
Adjunct to bv. Unidirectional Drain into venous circulation Drain protein rich plasma/ecm fluids Immune system
How backflow prevents in lymphatic vessels?
Lv larger in size?
What is a lymphangion?
In SI what are they called?
Compared to cap (2)?
Fucntion of anchoring filaments with Lymphatic Capp?
Valves.
Larger - more sm - contraction - propulsion of fluids
Functional unit between 2 valves
Lacteal
1)2) more permeable, lack basal lamina
Prevent vessel collapse under increased pressure
What forms the intrinsic enteric nervous system? (2)
Meissner and myenteric plexuses
