BIOL 460: Final Exam
51 Cards in this Set
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Reasons why myocardium cannot sustain contraction
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-not organized into motor units (no asynchronous activation)
-myocardial cells have a very long refractory period
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SA Node
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-pacemaker of the heart that generates AP automatically
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Atrioventricular node
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-composed of specialized cardiac myocites, propagate AP more slowly
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Bundle of His
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-(AV bundle)
-cells of AV node are continuous with this
-divides into left/right bundle branch that produces fibers called pukinje fibers
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purkinje fibers
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-follow the bundle of His
-terminate in papillary muscle
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Ectopic Focus
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other cells beside SA node cells that function as a pacemaker
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Electrocardiogram
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(ECG/EKG)
-Studies ion currents through skin
-Contains P wave, QRS wave and T wave
-Can be used to determine cardiac arrhythmias
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P wave
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depolarization of atrial myocardium
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QRS wave
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depolarization of ventricular myocardium
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T wave
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repolarization of ventricular myocardium
-ST segment represents plateau phase
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Brady cardia
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heart rate of <60 bpm
-Athletes
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Tachycardia
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heart rate of >100 bpm
-normal during excercise due to increase of sympathetic stimulus of SA node
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Sinus Tachycardia
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SA node is generating under normal conditions
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AV Node block
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caused by damage to AV node
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P-R interval
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-Time between the P wave and R portion of QRS (.12-.2 sec)
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Types of AV Node block
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-1st degree AV node block: P-R interval >.2 sec
-2nd degree AV node block: AP are not spread to ventricular myocardium, P wave is not followed by QRS: 1/3 or 1/4 impulses make it through the node
-3rd degree AV node block: complete blockage: AV node never passes AP into ventricular myoc…
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Flutter and fibrillation
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-extremely rapid rates of electrical excitation
-occur in both atrial and ventricular myocardium
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Flutter
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very rapid heart rate (200-300 bpm)
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Fibrillation
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parts of myocardium are generating AP and others aren't
-not pumping blood
-enlarged heart/scar tissue will slow AP through Ventricular myocardium
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Capillaries
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-Smallest blood vessels in body ( 40 bill/body)
-supplied w/ blood by arteriole
-wall of capillary is endothelium composed of endothelial cells-simple squamous (Very thin)
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Blood flow through capillaries
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blood travels through capillaries, exchange materials, venules, veins
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types of capillaries
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-Fenestrated
-Continuous
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Fenestrated Capillaries
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-openings between endothelial cells, porous
-fenestrae small enough to prevent cells from traveling though but large enough to allow water ions and AA to travel (paracellular)
-Found in kidneys, endocrine glands and intestines
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Continuous Capillaries
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-less porous than fenestrated, plasma membrane of endothelial cells folds inward
-paracellular movement is uncommon
-pinocytotic vesicles
-transcellular transport
-found in muscles, lungs and CNS
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Layers of Arteries/Veins
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-Tunica externa- connective tissue
-Tunica media: against the lumen, smooth muscle and connective tissue
-Tunica intima: endothelium
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Types of arteries
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-Arterioles
-Elastic arteries
-Muscular arteries
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Arterioles
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-Smaller arteries
-supply blood to capillaries
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Elastic arteries
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-large in size
-have layers of elastic connective tissue in addition to smooth muscle in tunic media
-elasticity allows structure of arteries to keep blood pressure at relatively constant levels
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Muscular arteries
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-smaller than elastic, less connective tissue and more smooth muscle
-vasoconstriction- contraction of smooth muscle of a blood vessel
-Vasodilation- relaxation of smooth muscle of blood vessel
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Veins
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-Venules
-collagen is not very stretchy
-valves prevent blood from travelling backwards, leads blood to heart
-Varicose vein: a vein that has been stretched becasue the elasticity has "worn out"
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Venules
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-type of vein
-smallest vein recieve blood from capillary
-form together to fuse large veins
-blood pressure is 10mHg
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Lymphatic system
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-return excess tissue fluid to the blood stream
-lymph vessels
-also has a filter/immune function, return escaped plasma proteins to the blood and fat absorption in the small intestine
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lymph
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tissue fluid within a lymph vessel
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lymph vessels
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-Lymph capillaries: smaller
-Lymphatics: larger, thinner in structure than veins
-valves allow one way travel to heart
-Two large lymph vessels
--Thoracic duct and right lymphatic duct
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thoracic duct
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largest lymphatic empties lymph into left subclavian vein
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Right lymphatic duct
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receives lymph from right arm/chest/head and carries lymph into right subclavian vein
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Lymph Nodes
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-similar in structure to a kidney bean, contains connective tissue (leucocytes and macrophages)
-trabeculae
-afferent lymphatics
-efferent lymphatics
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trabeculae
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connective tissue partitions that divide lymph node into regions
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afferent lymphatics
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transport lymph towards lymph node
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efferent lymphatics
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transport lymph away from lymph node
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Metastases
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spreading of cancer cells thoughout the body
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Plasma proteins cause...
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hypertonicity
-too large to leave blood capillaries
-important for blood to be hypertonic relative to tissue fluid which is hypotonic
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Fat absorption via lymph
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-products of protein digestion enter capillaries in villi
-fatty acids and monoglycerides are products of lipid digestion that enter cells in villi of small intestine
-chylomicron
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Chylomicron
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droplet of cholesterol/monoglycerides/fatty acids that are coated with proteins to make them soluble
-leave cells in villis via exocytosis
-can enter lacteal
-cisternae chyli- lacteals drain into these; these drain into thoracic duct
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lacteal
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lymph capillaries in villi of small intestine
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Atherosclerosis
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-disease affecting an arteriole blood vessel
-responsible for 50% of deaths/year in USA
-injury to endothelium of an artery trigger inflammation coupled with atheromas
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atheromas
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fatty plaques and formation of blood clots
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ways to injure endothelium
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-atherosclerosis
-chemicals in cigarette smoke
-not brushing/flossing teeth
-viral attack
-diabetes
-high BP
-ischemia- reduced blood supply to a tissue resulting in angina pectoris (chest pain)
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embolus
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traveling blood clot
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thrombus
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stationary blood clot
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Low density lipoproteins (LDLs)
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-made from chylomicrons
-coated with proteins (apolipoproteins)
-many cells have receptors for apolipoproteins and cells will undergo receptor mediated endocytosis
-liver cells will downregulate and allow LDLs to build up in blood stream
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BIOL 460: Test 2