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HA Ch. 20 (22)

Blood Vessels and Circulation

QuestionAnswer
oxygenated blood flows...from the heart through... away...arteries
arteries diverge into...and then into arterioles...capillaries of the organs
deoxygenated blood leaving capillaries is collected into...which merge/converge into venule...larger veins that carry blood towards the heart
pattern of oxygenated/deoxygenated blood applies to both the pulmonary and systemic circulation
pulmonary circulation; in lungs.. oxygen and carbon dioxide are exchanged
systemic circulation; in rest of the body... oxygen and nutrients are supplied to the body tissues
three tunics or layers of blood vessel walls tunica externa, tunica media, tunica intima
tunica externa ct layer consisting of collagen and elastic fibers (cells and fibers run longitudinally)
tunica media sheets of smooth muscle cells arranged circularly with circular sheets of elastin and collagen in between
tunica intima (lumen); endothelium =...in vessels that are...and also has a simple squamous epithelium...>1mm in diameter...subendothelial layer that lies just external to the endothelium
tunica externa (function) protects the vessel, further strengthens vessel walls and anchors the vessel to surrounding sturctures
tunica media; vasoconstriction decreases diameter of blood vessel when smooth muscle cells contract
tunica media; vasodilation increase diamter of blood vessel when relaxed
tunica media's...convey..for.. elastin and collagen...elasticity and strength...resisting the blood pressure placed on the vessel wall by each heartbeat
tunica intima has flat endothelial cells that form smooth surface, which minimizes the friction of blood moving across them
arteries conduct...and veins conduct.... blood flow away from the heart....blood towards the heart
arterial... BP vs venous BP
veins have...compared to similar-sized arteries wider lumens
arteries have ...compared to veins thicker tunica media
veins have thicker tunica externa
veins have..arteries do not have... valves
walls of arteries are generally...compared to those of veins ticker (retain their round shape) whereas veins tend to collapse
elastic laminae exist in arteries only, not in veins
three types of blood vessels arteries, capillaries, veins
3 subtypes of arteries elastic arteries, muscular arteries, arterioles
arteries conduct blood away from the heart
in the systemic circuit, arteries carry oxygen-rich blood to capillaries of organs/tissues
in the pulmonary circuit, arteries carry oxygen-poor blood to the lungs
the tunica media is thicker than the tunica externa in arteries
elastic arteries are in the aorta and major branches
elastic arteries are the largest arteries near the heart
the elastic arteries are low... resistance conduits meaning that they are conducting arteries
elastic arteries have increased elastin in walls, thick elastin sheets in tunica media
there is a high...content in elastic arteries that dampens the... elastin...surges of BP
muscular arteries = distributing arteries
muscular arteries lie distal to the elastic arteries
muscular arteries supply organs
muscular arteries are muscular because tunica media is thicker
unique feature of muscular arteries: especially thick sheets of elastin lie on each side of the tunica media
(muscular arteries) internal elastic lamina between the tunica intima and tunica media
(muscular arteries) external elastic lamina between the tunica media and tunica externa
arterioles are the smallest of the arteries
arterioles are low... resistant conduits meaning they are conducting arteries
the tunica media of the arterioles consists of only 1-2 layers of smooth muscle cells
larger aterioles include 3 tunics and internal elastic lamina
smaller arterioles are comprised of just a layer of smooth muscle cells and underlying endothelium
arterioles regulate the amount of blood flow to capillary bed and regulate systemic BP via changing arteriole diameter
3 types of capillaries continuous, fenestrated, sinusoidal cappillaries
capillaries are the...of blood vessels, but are just...enough for smallest...large...erythrocytes
structure of capillaries a single layer of endothelium is surrounded by basal lamina
capillaries are the most important blood vessel type because they renew and refresh interstitial fluid
capillaries deliver oxygen and nutrients
capillaries remove co2 and nitrogenous wastes
capillaries in the lungs oxygen enters the blood and co2 leaves it
in the small intestine, capillaries receive digested nutrients
in endocrine glands, capillaries pick up hormones
capillaries in kidneys, nitrogenous wastes are removed from the blood
capillary beds are structures by which capillaries supply cells in tissues and are networks of body's smallest blood vessels
metarteriole structural intermediate between arteriole and capillary
thoroughfare channel structural intermediate between capillary and venule
thoroughfare channel proceed to join venules, receive true capillaries along the way
precapillary sphincters are smooth muscle cells that wrap around the root of each true capillary where it leaves the metarteriole
precapillary sphincter functions to regulate blood flow to tissue, by opening and closing, according to the tissue's needs
most tissues and organs contain a rich capillary supply
tendons and ligaments have poor capillary supply
epithelia and cartilage have no capillary supply, blood supply from CTs
cornea and the lens also have no capillary supply, nourished by aqueous homor and other sources
capillary permeability is the anatomical basis of how substances are delivered and picked up
capillary structure is well suited for their function in the exchange of nutrients and wastes between the blood and the tissues through the tissue fluid
tight junctions block passage of small molecules
intercellular clefts small molecules exit and enter the capillary
pericytes are...shaped cells whose... spider...thin processes form awidely spaced network that does not interfere with capillary permeability
pericytes strengthen and stabilize the capillaries
continuous capillaries are the more common type
cont. capillaries have...cells that are connected by...and occur in most.. endothelial...tight junctions...organs such as skeletal muscles, skin and the central nervous system
fenestrated capillaries have...that span the...and occur only where there are... fenestrations(pores)...endothelium...exceptionally high rates of exchange
sinusoids sinusoidal capillaries
sinusoids are...capillaries containing both wide, leaky, twisted...expanded and narrowed regions
sinusoids are usually fenestrated
sinusoids have...cells with fewer... endothelial...cell junctions
in some sinusoids... intercellular clefts are wide open
sinusoids occur wherever extensive exchange of large materials, proteins or cells occur
sinusoids function in decreasing blood flow rate to allow time for the many exchange that occur across organ walls
there are...routes of capillary permeability four
direct diffusion of...across the... oxygen and co2...endothelium
intercellular clefts allow most of small molecules to enter and exit capillaries
caveolae allow large molecules to enter and exit
fenestrations in...allow some... fenestrated capillaries...small molecules to enter and exit
low permeability capillaries exist in blood brain barrier
low permeability capillaries prevents all but the most vital molecules from leaving the blood and entering the brain tissue
low perm. caps have a lack of structural features that account for capillary permeability
low perm caps have complete tight junctions in brain caps
there are no...in low perm caps intercellular clefts
low perm caps have...but not... cont. caps...fenestrated
low perm caps lack caveolae
...and...may cross the BBB uncharged...lipid soluble molecules (o2, co2, and anesthetics)
3 types of veins venules, veins, vena cavae
veins conduct blood from capillaries toward the heart
in systemic circuit o2 poor blood from capillaries
in pulmonary circuit o2 rich blood from the lungs
venous BP < arterial BP
venules are the smallest of the beins
venules have 1-2 layers of smooth muscle in tunica media and tunica externa
postcapillaryvenules are the..venules which are comprised of... smallest...endothelium on which lie pericytes
venules function like capillaries
venules join or merge to form veins
veins hold fully 65% of body's blood
tunica externa of veins is...than... ticker...tunica media
vena cavae is the largest of the veins
vena cavae has a tunica externa that is...by... further thickened...longitudinal bands of smooth muscle
vena cavae have decreased elastin content compared to arteries
several mechanisms counteract the low venous BP and help blood flow along its course towards the heart
valves prevent backflow of blood away from the heart
valves are cusps formed from tunica intima
valves are most abundant in veins of the limbs because superior direction of venous blood flow is opposed by gravity
valves found in...counteract the low venous BP veins of the head and neck
there are no valves in the thoracic and abdominal cavities
...of our body and limbs counteract the low venous BP normal movement
skeletal muscular pump contracting muscles press against veins, forcing valves proximal to area of contraction open and propelling blood towards the heart
venous BP is lower due to thinner walls, wider lumen, thinner tunica media, thicker tunica externa
vascular anastomoses have...channels where... collateral...vessels unite or interconnect
vascular anastomoses provide alternative pathways for blood to reach a given body region
arterial anastomoses; most organs receive blood from > 1 arterial branch and neighboring arteries often communicate with one another to form anastomoses
arterial anastomoses occur around..where...may... joints...active body movements...hinder blood flow through one channel
occlusion in arterial anastomoses causes severe tissue damage in some organs
venous anastomoses occur more frequently than arterial anastomoses
venous anastomoses are visibly located through the skin on dorsum of hand
occlusion in venous anastomoses rarely blocks blood flow or leads to tissue death
vasa vasorum are little veins in the tunica externa of larger arteries and veins
vasa vasorum function as the blood supply of blood vessel walls
vasa vasorum nourish the outer half of the wall of the larger vessel
no vasa vasorum is found in small blood vessels
vasa vasorum may arise as tiny branches from the same large vessel or as a small branch from other, nearby, arteries and veins
pulmonary circulation begins as...which exits... o2 poor blood leaves the right ventricle of the heart via the pulmonary trunk...anterior to the aorta and splits into right and left pulmonary arteries inferior to the aortic arch
each pulmonary artery enters each lung, at the medial aspect, and branches in the lungs as follows
lobar arteries repeated branching of arteries decrease in size and branch along with respiratory bronchi
pulmonary capillaries that surround the..where...occurs across the... alveoli...gas exchange...respiratory membrane
pulmonary tributaries empty...into... newly oxygenated blood...superior and inferior pulmonary veins
superior and inferior pulmonary veins exit the medial aspect of each lung
each pair of pulmonary veins extend from the lungs to the left atrium of the heart
the systemic circulation beings with o2 rich blood leaving the left ventricle of the heart through the aorta which progressively decrease in size
size of arteries (largest to smallest) elastic arteries, muscular arteries, arterioles
arterioles become...in capillary beds, which... metarterioles..nourish body tissues with oxygen and nutrients and thus blood becomes o2 poor
blood flows through...procees to join...and ends with the. thoroughfare channels...veins...two large vena cavae and the coronary sinus which empty into the right atrium of the heart
the systemic arteries leave the...and begin as the...which is divided into... heart...aorta...three parts (ascending aorta, aortic arch, descending aorta)
ascending aorta branches into 2 coronary arteries that supply the heart wall
aortic arch branches into 3 arteries that run superiorly and supply the head, neck, upper limbs and superior part of the thoracic wall
3 arteries of the aortic arch braciocephalic trunk, left common carotid artery, left subclavian artery
brachiocephalic trunk ascends to the right toward the base of the neck and further divides
the brachiocephalic trunk divides into the right common carotid artery and the right subclavian artery
the r and l subclavian arteries give off branches...to the...and run.. vertebral artery, thryocervical trunk, costocervical trunk...neck..laterally onto the first ribs, underlying the clavicle and continue laterally to supply the upper limbs
the sections of the subclavian arteries exit...passing over the...and continue through the... the thoracic cavity...outer border of the first rib...upper limb
subclavian arteries are named according to the specific region of the upper limb it supplies
subclavian branches into the axillary, brachial, radial, ulnar, plamar, digital
most parts of the head and neck are supplied by the common carotid arteries which divide into an external and internal carotid artery each
both the r and l external carotid arteries supply most tissues of the head external to the brain and orbit and send branches
external carotid arteries send branches to the superior thyroid artery, lingual artery, facial artery, occipital artery
superior thyroid artery supplies the thyroid gland and larynx
lingual artery supplies the tongue
facial artery supplies the skin and muscles of the anterior face
occipital artery supplies the posterior part of the scalp
each external carotid ends near the temporomandibular joint
external carotid splits into the superficial temporal artery and maxillary artery
superficial temporal artery supplies most of the scalp
maxillary artery branches also to the teeth, cheeks, nasal cavity and muscles of mastication
the internal carotid arteries supply the orbits and most of the cerebrum
internal carotid enters the sella turcica of sphenoid bone just posterior to the foramen and branches off
internal carotid branches off as the opthalamic artery(eyes and orbits), anterior and middle cerebral arteries(supplies 80% of the cerebrum)
each anterior cerebral artery anastomoses with each oter through a short anterior communicating artyer
the posterior brain is supplied by the...which ascend the..sending branches to the... r and l vertebral arteries...vertebral column...vertebrae and cervical spinal cord
the right and left vertebral arteries join to form the unpaired basilar artery within the cranium
at the border of the pons and medulla, the basilar artery divides into a pair of...and is connected to the...by the.. posterior cerebral arteries...middle cerebral arteries anteriorly...posterior communicating arteries
together, the posterior cerebral arteries and the middle cerebral arteries and the anterior communicating artery, complete the formation of an arterial anastomosis called the cerebral arterial circle
the cerebral arterial circle forms a loop around the pituitary gland and optic chiasma
the cerebral arterial circle unites the brain's anterior and posterior blood supplies provided by the internal carotid and vertebral arteries
the cerebral arterial circle provides alternate routes for blood to reach the brain areas that are affected if either a carotid or vertebral artery becomes occluded
descending aorta runs posterior to the heart and inferiorly on the bodies of the thoracic and lumbar vertebrae
the descending aorta has two sections thoracic aorta and abdominal aorta
the thoracic aorta goes from...and supplies the... T3-T12...thoracic organs and body wall
abdominal aorta goes from...and supplies the...and divides into the...which supply the... T12-L4...abdominal organs...r and l common iliac arteries...pelvis and lower limbs
the common iliac arteries descend...and each section is named according to the each limb...specific region of the lower limb it supplies
the common iliac artery supplies the femoral, politeal, anterior and posterior tibial arteries
branches to the...and other...are.. bodywall, kidneys...structures outside the peritoneal cavity...paired
branches to the body wall, kidneys and other non peritoneal cavity structures originate along the lateral surfaces of the abdominal aorta
the major branches to visceral organs are...and arise on the... unpaired...anterior surface of the abdominal aorta and they extend into the mesenteries to reach the visceral organs
three unpaired arteries are the celiac trunk, superior and inferior mesentary arteries
the celiac trunk is superiorly located branch that delivers... blood to the liver, stomach, esophagus, gallbladder, duodenum, pancreas, and spleen
celiac trunk divides into left gastric artery, splenic artery and common hepatic artery
left gastric artery supplies stomach and inferior portion of esophagus
splenic artery supplies the spleen and arteries to the stomach and pancreas
common hepatic trunk supplies arteries to the liver, stomach, gallbladder, and duodenal area
the superior mesenteric artery arises about...inferior to the...to supply arteries to the 2.5 cm...celiac trunk...pancreas and duodenum, small intestine and most of the large intestine
the inferior mesenteric artery delivers blood to the terminal portions of the colon and rectum
the sytemic veins mostly run...but there are important differences in the... ...with corresponding arteries...distribution of arteries and veins
the superior vena cava arises from the merging of the r and l brachiocephalic veins
the r and l brachiocephalic veins are each formed by the union of an internal jugular vein and a subclavian vein
the inferior vena cava begins inferiorly as the union of the two common iliac veins at the level of vertebra L5
the inferior vena cava; blood returning from the abdominopelvic viscera and the abdominal wall reaches the heart via the IVC
most venous tributaries of the IVC share the names of the corresponding arteries
veins of the head and neck; most blood draining from the head and neck enters 3 pairs of veins
3 pairs of veins in the head and neck internal jugular veins from the dural sinuses, external jugular veins, vertebral veins
veins of the upper limbs are either deep or superficial
deep veins include palmar venous arches to the radial and ulnar veins which unite and form the brachial veins of the arm and enter the axilla as the axillary veins which become the subclavian vein at the first rib
the palmar venous arches supply the hand
superficial veins include cephalic veins, basilic veins, median cubital veins, median veins of the forearm
veins of the thorax empty blood from the...into the...whereas blood from the...and from some of the...drains into the... first few intercostal spaces...brachiocephalic veins...other intercostals spaces...thoracic viscera...azygos system
the azygos system of veins is a group of...which flank the..and ultimately empty into the... veins...vertebral column...SVC
the azygos system consists of the azygos vein, hemiazygos vein, and the accessory hemiazygos vein
veins of the abdomen include the lumbar, gonadal, renal, suprarenal, hepatic veins
portal system is a set of...in which...lie between the vessels...two capillary beds, interconnected by a vein...initial artery and the final vein
hepatic portal system is a special subcirculation that drains the digestive system
veins of the pelivs and lower limbsare either deep or superficial and ascend and merge to ultimately become the IVC
deep veins of the pelvis annd lower limbs share the names of the arteries they accompany
the deep veins of the pelvis and lower limbs include the plantar, tibial, fibular, popliteal, femoral, internal/external iliac, common iliac veins
superficial veins of the pelvis and lower limbs includes the dorsal venous arch of foot, great saphenous veins that empty into the femoral vein and the small saphenous veins that empty into the popliteal vein
Created by: handrzej