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Flashcards in Blood Vessels Deck (30):

3 Classes of blood vessels

1. Arteries: Carry blood away from heart (become progressively smaller as they branch - finally result in capillaries)
2. Capillaries
3. Veins: return blood to the heart & become progressively larger as they merge and are closer to heart


Blood Vessel Tunics ( 3 layers)

-vasa vasorum

1. Tunica Externa (adventitia): CT that helps anchor blood vessel to organ
Vasa Vasorum: Small network of arteries that supply blood to tunica externa
2.Tunica media: comprised of circularly arranged smooth muscle
-sympathetic input = vasoconstriction
-parasympathetic input = vasodilation
3. Tunica Intima (interna): composed of an endothelium (simple squamous lining inside of arteries and veins) and a subendothelial layer of areola CT


Blood Vessel tunics - differences between artery and vein

-Vein has thin media layer, but very thick externa
-also has extensions of endothelial lining called valves that prevent the backflow of blood to lower parts of the body

-Arteries: need to maintain high pressure - have v. narrow lumen (space for blood to travel) and very thick media.

*When no blood in vein, it collapses (due to thin media)


Types of arteries (3)

-Elastic arteries
-Muscular arteries


Elastic Arteries

-Largest of arteries
-most near the heart
-Elastic fibers present in all three tunics allows these arteries to stretch under the increased pressure generated by bloodflow from the heart
-branch into muscular arteries

-e.g. aorta, pulmonary, brachiocephalic, common carotids, subclavians


Muscular Arteries

-Medium diameter arteries
-Possess elastic fibers in 2 concentric rings between the three tunics;
1. Internal elastic lamina (separates tunica intima & tunica media)
2. External elastic lamina (separates tunica media & tunica externa)
-Have a proportionately thicker tunica media



-smallest arteries
-less than 6 cell layers of smooth muscle in tunica media
-sympathetic innervation causes vasoconstriction (elevation of blood pressure)
-parasympathetic innervation causes vasodilation (lowering of blood pressure)



-Smallest of all blood vessels
-Diameter only slightly larger than an erythrocyte
-wall = only tunica intima
-only type of blood vessel where metabolic exchange can occur between blood and cells outside of the bloodstream


Capillary Beds

-thoroughfare channel
-postcapillary venule
-true capillaries

-Formed from capillaries (10-100)
-Fed by a metarteriole (vessel branch of arteriole) - proximal end surrounded by smooth muscles, while distal end (called thoroughfare channel) lacks smooth muscles
-Thoroughfare channel connects to a postcapillary venule (start of vein system)
-Branches from metarteriole that begin w/ ring of smooth muscles of their walls = true capillaries


Types of Capillaries (3)

1. Continuous: most common type - endothelial cells form a continuous and complete lining, aided by presence of tight junctions
2. Fenestrated: endothelial cells possess small holes to allow fluid exchange between blood and interstitial fluid (i.e. glomerulus)
-allows small molecules such as nutrients to release
3. Sinusoid: have big gaps between endothelial cells that promotes transport of large molecules & cells to & from blood
-In liver and some lymphatic tissues & spleen


Veins - what they do, function

-pressure compared to arteries

-blood vessels that drain capillaries & return blood back to heart
-Pressure in veins much lower than in arteries
-at rest, holds about 60% of body's blood
-function as blood reservoirs


Veins -size

-small, medium & large
-skeletal muscles' role

-larger than venules
-smaller & medium sized travels w/ muscular arteries
-large veins travel w/ elastic arteries
-possess valves b/c blood pressure in veins too low to overcome force of gravity
-formed from tunica intima (prevent blood from pooling in limbs)
-skeletal muscles assist - as they contract, also pump blood towards heart (SKELETAL MUSCLE PUMP)


Venules - what they are

-where located

-smallest veins
-smallest ones located at distal end of capillary bed & called postcapillary venules
-Diapedesis (migration of leukocytes from bloodstream to body) occurs through walls of postcapillary venules
-merge to form veins


Blood Pressure -what it is

-Systolic vs diastolic
-how expressed

-Is the force per unit area that blood places on the inside wall of a blood vessel
-systolic pressure > dialostic pressure due to force of ventricle contraction
-expressed as ratio: numerator = systolic, denominator = diastolic
-average adult = 120/80 mmHg
-pressure produced in ventricles of heart
-pressure decreases as go further through network


Factors that affect blood pressure (5)

-Increased blood volume
-increased cardiac output
-some medicines & drugs (can either increase or decrease)
-overweight or less healthy tend to have increased blood pressure


General arterial flow out of the heart

-What ascending aorta branches into (2)

-What aortic arch branches into (3)

-oxygenated blood pumped out of left ventricle into ascending aorta - gives off to two branches;
1. Left coronary artery
2. Right coronary artery
Aortic arch gives three branches;
1. Brachiocephalic trunk - bifurates into right common carotid & right subclavian arteries
2. Left common carotid
3. Left subclavian artery


General arterial flow out of the heart

-Descending thoracic aorta
-when name changes
-When bifurcates (goes into 2)

-Descending thoracic aorta follows aortic arch & gives off several branches to thoracic wall (pretty much touches vertebral body)
-Called descending abdominal aorta when passes inferior & posterior to diaphragm
-at fourth lumbar vertebra, aorta bifurcates into left & right common iliac veins
-further divide into internal and external iliac arteries


General venous return to heart

-Inferior & superior vena cava

-Inferior vena cava returns blood to right atrium from lower limbs, pelvis & perineum & abdominal structures
-superior vena cava formed from fusion of right & left brachiocephalic veins - drains into right atrium


Blood flow through head and neck
-Major arteries

-Left & right common carotid arteries supply most of blood
-at superior border of thyroid cartilage, they divide into internal and external carotid arteries


Blood flow through head and neck
-Major veins

-Venous blood return through internal jugular vein or external jugular vein
-both drain into subclavian vein & then into brachiocephalic vein


Blood flow through cranium

-Most venous blood drains through dural venous sinuses
-these large veins formed between two layers of dura mater
-no valves in dural venous sinus system so blood can flow in more than just one direction


Blood flow through gastrointestinal tract

-3 unpaired arteries emerge from anterior wall of descending abdominal aorta
-are responsible for supplying the organs of the gastrointestinal tract
1.celiac trunk
2. superior mesenteric artery
3. inferior mesenteric artery


Venous return from abdomin

-hepatic portal vein - where it goes
-what it is formed by (3)

-hepatic portal system is a network of veins that drains blood from gastrointestinal organs and shunts the blood to the liver
-Hepatic portal vein delivers nutrient rich blood to liver
-formed by merging of:
1. Inferior mesenteric vein (drains distal part of colon)
2. Splenic vein: drains spleen, pancreas & stomach
3. Superior mesenteric vein (drains small intestines, proximal part of colon, pancrease & stomach)


Arterial flow through upper limb

-From subclavian to fingers

-Left and right subclavian arteries supply blood to upper limbs
-As subclavian artery passes over lateral border of first rib, called axillary artery
-supplies shoulder and thoracic region
-as passes inferior border of teres major muscle, name changes to brachial artery
-in cubital fossa, brachial artery bifurates into ulnar and radial arteries
-these arteries anastomose & form superficial & deep palmar arches in palm of hand
-digital arteries emerge from arches


Superficial venous drainage of upper limb

-On dorsum of hand, dorsal venous network drains into basilic and cephalic veins
-in cubital fossa, these 2 veins connected by median cubital vein - common vein used for venipuncture


Arterial flow through lower limb

-RIght and left external iliac artery supplies blood to lower limb
-as passes inferior to inguinal ligament, name changes to femoral artery - gives off a branch called deep femoral artery
-deep femoral artery supplies hip joint via medial and lateral circumflex arteries
-Popliteal artery (region behind knee)
-Have anterior tibial artery, posterior tibial artery and fibular artery


Superficial venous drainage of lower limb

-On dorsum of foot, dorsal venous arch drains into great saphenous vein medially and small saphenous vein laterally
-great saphenous vein drains into femoral vein & small saphenous vein drains into popliteal vein


Pulmonary circulation

-responsible for carrying deoxygenated blood from right side of heart to lungs & returning newly oxygenated to left side of heart
-In this circulation, arteries carry deoxygenated blood and veins carry oxygenated blood *opposite of systemic circulation*
-deoxygenated blood exits righ ventricle into the pulmonary trunk, bifurcates into right and left pulmonary arteries that go to lungs
-Arteries branch into arterioles, then capillaries and finally return to left atrium as pulmonary veins


Fetal and Newborn Circulation

-features of fetus
-3 things unique to fetal circulation

-Lungs don't work in fetus - get O2 from umbilical vein
-is a hole b/w left and right atrium for blood to bypass lungs = foramen ovale (prevents developing lungs from overloading with blood)
-Ductus arteriosus, formen ovale & ductus venosus are unique to fetal circulation
-become ligaments once not needed


Fetal and Newborn circulation;

What structures turn into after birth:
-Ductus arteriosus
-ductus venosus
-foramen ovale
-umbilical arteries
-umbilical vein

-Ductus arteriosus -ligamentum arteriosum
-ductus venosus-ligamentum venosum
-foramen ovale - fossa ovalis
-umbilical arteries -Medial umbilical ligaments
-umbilical vein - round ligament of liver (ligamentum teres)