Start from base of Heart (Left Ventricle) Ends at Right Atrium of Heart
Three walls of blood vessel
Tunica Intima (inner) Tunica Media (middle) Tunica adventitia (outer)
What does the thickness of a vessels wall indicate?
It depicts the amount of pressure the vessel is designed to withstand.
Simple Squamous epithelium Elastic Layer
Smooth muscles Elastic CT Thickest layer in Arteries
Thin CT of elastin and collagen fibers
Tunica Media - Elastic Arteries
closest to the heart Has more elastic tissue
Tunica Media - muscular arteries
Predominantly smooth muscle with less elastic tissue
Tunica media smooth muscle is innervated by
Sympathetic nervous system
What does the sympathetic stimulation cause in a blood vesssel?
Contractions, known as vasoconstriction Lack of stimuli from PARA, leads to vasodialation (widening of lumen)
System communication Nervous
Fight of Flight -increases heart rate -breathe faster -pupils dilate -slow digestion -cold, sweaty -liver releases sugars into blood
Rest and Digest -heart slows -breathe slows -blood flow to GI increases -pupils constrict
-Carry blood away from heart -Elastic to handle high pressure -Branch into arterioles
-Smaller than arteries -Composed mostly of smooth muscle -fewer than 5 layers of sm. muscle -control blood distribution to various regions of body by contracting and relaxing of their smooth muscle
-Single Layer of squamous epithelial cells -semipermeable -lot of cap. in muscle and nervous tissue - few in cornea & cartiladge - Form capillary beds.
Branched networks within tissues and organs
-Regulate flow into capillary bed -solutes cross capillary wall by diffusion -plasma proteins stay (too big) so they help with osmotic pressure.
The filtration forces the formation of fluid in the interstitial space and results in hydrostatic pressure
Capillaries (2 types)
endothelial cells form a complete tube type
Increased pores for fenestrated, the endothelial cells have large gaps (fenestrae) in them....thereby increasing the 'leakiness' of the capillary
Which arterial wall exhibits greatest variation?
What is the composition of a capillary?
a single layer of squamous epithelium and a basement membrane
Which vessels of the vascular system exhibit valves?
(come after capillaries in bed in flow) -Merge to form veins -tunica media and adventitia composed of LCT
-Carry blood towards the heart -path of veins parrallels that of arteries -Same 3 layers as arteries (much smaller TUNICA MEDIA) -possess valves -blood pressure is lower than in arteries -blood may pool as reservoir -tunica adventitia exhibits smooth muscle -have valves
What is the function of valves in the vascular system?
permit unidirectional flow (prevent backflow)
What is the purpose of having smooth muscle in tunica adventitia in veins?