Ch.19: Blood Vessels Flashcards
The _______ of the body form a closed delivery system that begins and ends at the heart
Blood vessels
What are the three major types of blood vessels
Arteries, Capillaries and Veins
Characteristics of Arteries
transport blood away from the heart thicker tunica media No Valves, Narrow Lumen More elastic and collage Blood pressure is higher Stay open with no present of blood
Characteristics of Veins
Transport blood toward the heart thicker tunica externa larger lumen, Has Valves Less elastic, and collage Walls collapse in no blood is in it BP is low
What are the three distinct layers of the blood vessel wall? Innermost to outermost
Tunica Intima
Tunica Media
Tunica Externa
Characteristics of Tunica Intima
innermost layer
Endothelium lining, simple squamous epithelium
slick surface, minimizes friction as blood moves
Characteristics of Tunica Media
Smooth muscle cells and sheets of elastin
regulated by sympathetic vasomotor nerve fibers
Vasoconstriction/ Vasodilation
Bulkiest layer in arteries
Influence blood flow and Blood pressure
Characteristics of Tunica Externa
Outermost layer of the wall
loosely woven collagen fibers
protect and reinforce the vessels, anchors
Three types of Arteries are
Elastic Arteries
Muscular Arteries
Arterioles
Characteristics of Elastic Arteries
thick-walled arteries near the heart largest in diameter Sometimes called conducting arteries More elastin than any other vessels Presents all three tunics, MEDIA MOST inactive of Vasoconstriction pressure resevoirs, expanding and recoiling as the heart eject blood Ex: aorta, pulmonary trunk, brachiocephalic
Characteristics of Muscular arteries
Deliver blood specifically to organs Distributing Arteries Thickest tunica media of all vessels More smooth muscle than elastic More active in vasoconstriction, less stretching Ex: femoral, renal , splenic, coronary
Characteristics of Arterioles
Smallest of the Arteries
Tunica media is chiefly smooth muscles with a few elastic
maximum resistance
Significant role in BP and Blood Flow
Diameter changes due to Sympathetic/ Endocrine
The microscopic _________ are the smallest blood vessels
Capilaries
Characteristics of Capillaries
thin walls, consist of just thin tunica intima
Blood flow is very slow, narrow
Exchange between the tissue and blood
Spider-shaped ________, smooth muscle-like cells that stabilize the capillary wall and help control the capillary permeability
Pericytes
Capillaries is in all tissues except
Cartilage and epithelia
Cornea and lens of the eye
Three types of Capillaries are:
Continuous Capillary
Fenestrated capillary
Sinusoid Capillary
Describe Continuous Capillary
most abundant in skin and muscles most common tight junctions Does not Leak Intracellular clefts , opening
Describe Fenestrated Capillaries
Riddled with oval pores
much more permeable to fluid and small solutes
found where active capillary absorption or filtrate formation occurs
small intestines, endocrine organs, kidneys
Describe Sinusoid Arteries
Higly modified and leaky
Found only in the liver, bone marrow, spleen, and adrenal medulla
Have irregulary shaped lumens and are usually fenestrated
large intracellular clefts
Stellate macrophages, remove and destroy any bacteria
Capillaries do not function independently, they form interweaving networks called _____
Capillary bed
The flow of blood from an
Arteriole to a venule
A capillary bed consist of two types of vessels
Vascular shunt (metarteriole- Postcapillary venule True capillaries (exchange happens)
A cuff of smooth muscle fibers, called _____ surrounds the root of each true capillary and acts a valve to regulate blood flow into the capillary
Precapillary sphincter
Capilaries unite to form ______ , the smallest is postcapillary venule, exteremely porous
Venules
_________ formed from folds of the tunica intima, prevent blood from flowing backward
Venous valves
Veins are called ________ because they can hold up to 65% of the body’s blood supply at any time
Blood reservoirs/ Capacitance Vessels
________ veins that are tortuous and dilated because of imcompetent leaky valves
Varicose veins
______ Part of the wall thins and balloons out, cause by weak spot in the vessel , pressure may rupture blood vessel
Aneurysm
Atherosclerosis
Plaque
Arteriosclerosis
Hardening of Arteries and calcification, plaque
__________ are highly specialized flattened veins with extremely thin walls composed only of endothelium
Venous Sinuses
