Exam II

• veins
• arteries
• vaso vasorum

Carry blood to the heart from the tissues

Carry blood away from the heart towards the tissues

• Tunica interna
• Tunica media
• Tunica external (adventitia)

• endothelium-lines the lumen (simple squamous e. with direct contact with the blood)
• areolar connective tissue-underlying the endothelium
• contains a small amt of smooth muscle
• internal elastic membrane-indicator of boundary between t. interna and t. media

Composed of varying amounts of elastic fibers, circularly arranged smooth muscle, and thickness varies on pressue

• Composed primarily of loose connective tissue (contains collagen and elastic fibers)
• Scattered smooth muscle
• In larger arteries a well organized layer of elastic fibers (external elastic membrane)

• Smallest blood vessel carrying blood away from the heart
• Range from 4-12 micormeters in diameter
• Always connect arterioles to venules
• Permit the exchange of nutrients, waste, and gases between blood tissue cells and interstitial fluid
• Lack elastic fibers
• Form extensive networks inside a tissue
• Wall of capillary is composed only of an endothelium

• Special capillaries
• Wider diameter lumen
• More highly coiled
• Always connect arterioles to venules
• Found in specific locations including liver, spleen, adenphypophysis, and parathyroid gland
• Largely lined with phagocytic cells instead of endothelium

• Elasticity: stretches from large volume of blood and recoils to original size when blood is gone
• Contractility: due to circulary arranged smooth muscle fibers-narrows the opening of lumen "vasoconstriction"-smooth muscle relases-lumen opens "vasodilation"

• Non-anastamosing circulation
• Anastamosing circulation

• No connections between 2 arteries supplying the tissue
• Exanterior and posterior interventricular arteries
• both supply blood to right and left ventricle but are not connected to each other

• The 2 arteries are connected often near distal ends (ex. Circle of Willis)
• Common around joints
• Very common to vital organs
• Anastomoses help to equalize the pressure and distribution of blood

• Have the same 3 coats as arteries
• The blood has lost considerable pressure by the time it reaches the veins
• Still capible of moderate distention and recoil allowing them to adapt to minor changes in blood volume and pressure

• "Driving force" of blood pressure in the lower limbs is barely enough to overcome the pull of gravity
• Structurally veins conain a series of "one-way valves" to insure blood flow to the heart
• Weak valves can lead to extensive problems over time

• Offer little or no resistance to flow toward the heart
• Easily close against any flow away from the heart

• Allows blood to be pulled down by gravity and pooled in extremity (edema)
• Repetitive pooling of blood stretched out the wall of the vein (vericose vein)
• Can be a progressive problen-valve under weakened valve becomes weakened also
• stretched flabby vein allows more fluid to leak out of vein and causes edema of the surronding tissues
• Variscosities are common in superficial vessels of the leg and superficial vessels of the anal canal

• Fetus digestive, urinary, and respiratory systems are not functioning
• Fetus depends upon the maternal blood supply to provide the functions of those systems
• accomplished by exchange occuring in the placenta (responsible for the exhange of nutrients, wastes, and gases between maternal and retal blood---ocurs by typical process--difussion, osmosis, active transport, not by mixing blood, and passive exchange across the placenta)

• Blood passes through 2 capillary beds before returning to the heart
• Blood in the hepatic portal vein is rich in material absorbed in digestive organs
• Liver processes the blood before it goes into general circulation

• Monitor and regulate blood nutrient levels (high after a meal and low before a meal)
• Modify some nutrients to a more cell usable form
• Detoxify harmful materials that are absorbed
• Microbes are removed by phagocytosis "Kupffer cells"
• Receives only low O2 blood---not good for liver

• Foramen ovale: a calve (flap of tissue) in the opening of the inferior vena cava that directs blood through the foramen ovale (bypass the right ventricle)
• Ductus arteriousus: short vessle that connects the pulmonary trunk with the aorta-when the right ventricle ejects blood most of it passes throught the ductus arteriousus directly to the aorta

• Umbilical vein: closes and atrophies to become the round ligament
• Ductus venosus: closes and atrophies to become the ligamentum venosum
• Placenta: passes down the birth canal as after birth
• Foramen ovale: normally closes, atrophies, and becomes the fossa ovalis
• Ductus arteriosis-normally closes, atrophies, and becomes the ligamentum arteriosum

• Flow: volume of blood delivered to a vessel per minute
• Resistance: any mechanism that inhibits te movement (flow) of blood

• Cardiac is the principal determinant of flow and therefore the principle determinant of blood pressure
• Cardiac output is determined by 2 factors:stroke volume (force of ventrical contraction) and heart rate (reflexes, and, etc.)

• Viscosity of the blood-increasing blood viscosity increases resistance and therefore blood pressure (same with decreasing)
• 2 common ways to increase blood viscosity- increase plasma protein levels of albumin and increase the number of eryrthrocytes polycythemia
• Peripheral resistance offered by altering the lumen diameter of blood vessels
• Elasticty of vessel
• Length of vessel

• Aorta: 100mmHg
• Arteries (small and large): 100mmHg-40mmHg
• Arteroles: 40mmHg-25mmHg
• Capillaries: 25mmHg-12mmHg
• Venules: 12mmHg-5mmHg
• Veins: 10mmHg-5mmHg
• Vena cava: 2mmHg