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5 basic parts of the vascular system
- arteries
- arterioles
- capillaries
- venules
- veins
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Large muscular vessels that carry blood away from the heart
arteries
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branch from arteries and enter tissues, regulate amount of blood entering tissues
arterioles
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How do arterioles regulate the amount of blood entering the tissues?
vasodilation and vasoconstriction
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widening of blood vessels resulting from relaxation of smooth muscle in the vessels
vasodilation
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narrowing of the blood vessels resulting from contraction of smooth muscle in the vessel walls
vasoconstriction
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microscopic vessels that connect arterioles with the venules
capillaries
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where are capillaries most numerous?
where activity is highest
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purpose of capillaries
to permit the exchange of oxygen, nutrients, and wastes between the blood and tissue cells
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collect blood from the capillaries and drain it into the veins
venules
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large vessels into which the venules flow for return of blood to the heart
veins
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open space of vessel through which blood flows
lumen
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how many major layers are found in a blood vessel?
- 3
- arteries have 2 additional lamina (membranes)
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3 layers of a blood vessel (starting with innermost)
- tunica interna (intima)
- tunica media
- tunica externa (adventitia)
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another name for the tunica interna
tunica intima
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What is the tunica interna composed of?
simple squamous epithelium and a basement membrane
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innermost layer of a blood vessel?
tunica interna (intima)
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What additional layer do arteries have in the tunica interna?
an elastic membrane - internal elastic lamina
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what is the tunica media made up of?
a thick layer of smooth muscle
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what is the middle layer of a vessel called?
tunica media
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what additional layer of the tunica media do arteries have?
external elastic lamina
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outside layer of blood vessels
tunica externa (adventitia)
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What is the tunica externa made up of?
very tough layer of collagenous and elastic fibers
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another name for tunica externa?
tunica adventitia
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what are capillaries composed of?
only an inner lining of endothelium and a thin elastic basement membrane
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there is usually a ___________ _____________where the arterioles transition to capillaries
precapillary sphincter
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only present in veins and prevent the backflow of blood
- valves
- semi-lunar in structure
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What do the smooth muscles of the precapillary sphinters in the arterioles regulate?
the amount of blood entering most capillary beds - -the muscles especially
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where do capillary beds remain open virtually all the time (flow not regulated by precapillary sphincters)?
the brain
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Movement of fluids between vascular and interstitial compartments occurs across ________ _________.
capillary membranes
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Does fluid tend to move in or out of the arterial end of a capillary? by what means?
fluid moves out of the plasma into the interstitial fluid by filtration
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Does fluid tend to move in or out of the venous end of a capillary? By what means?
Fluid moves into the to the venous end from the interstitial compartment to the plasma
through reabsorption
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Is all fluid filtered at one end of the capillary bed reabsorbed at the other end?
No, fluid and protein not reabsorbed pass into the lymphatic system and eventually back into the cardiovascular system
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What sorts of materials that are filtered at one end of the capillary bed are not reabsorbed at the other end?
fluids and proteins
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state of near equilibrium at the arterial and venous ends of a capillary between filtered, reabsorbed, and lymphatic pickup
Starling's law of the capillaries
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The volume of blood in various parts of the cardiovascular system ________ __________.
varies considerably
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percentage of total blood volume in the systemic veins and venules
64%
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percentage of total blood volume in the systemic capillaries
7%
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percentage of total blood volume in the arteries and arterioles
13%
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percentage of total blood volume in the heart
7%
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percentage of total blood volume in the pulmonary vessels
9%
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Systemic veins are collectively called...
blood reservoirs
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What function do blood reservoirs serve?
blood storage
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process which causes blood to move to other parts of the body when the need arises
vasoconstriction
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in the event of hemorrhage, what do blood volume and pressure do?
drop
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What do blood reservoirs do when a hemorrhage occurs?
vasoconstriction causes the blood reservoirs to empty
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principle blood reservoirs of the body
- veins of the skin
- abdominal organs (liver, intestines, spleen are especially effective blood reservoirs)
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the largest blood reservoir
skin
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vascular term used to describe the contraction period of the ventricles
systole
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What term is used to describe the relaxation period of the ventricles?
diastole
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What happens to the arteries during systole?
they expand
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what happens in the arteries during diastole to assist in pushing the blood away from the heart?
the arteries recoil
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What causes the pulse?
the alternation between the expansion and recoil of the arteries after each systole of the left ventricle creates a traveling pressure wave
the arteries expand during systole and recoil during diastole
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What 2 instruments are used in taking blood pressure measurements?
stethoscope and sphygmomanometer
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What does one listen for when taking a blood pressure measurement?
Korotkoff sounds
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What range would one expect to hear Korotkoff sounds?
thoughout the blood pressure range
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How is measured blood pressure expressed
systolic over diastolic
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normal blood pressure
120/80
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blood pressure and velocity are highest in the _________
arteries
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Why are blood pressure and velocity lowest in the capillaries?
a dramatic collective increase in cross-sectional area within the capillaries
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what is the cross-sectional area of a vessel
space inside the vessel
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is blood pressure lower in the capillaries than in the arteries?
yes
- The pressure of arterial blood is largely dissipated when the blood enters the capillaries. Capillaries are tiny vessels with a diameter just about that of a red blood cell (7.5 µm). Although the diameter of a single capillary is quite small, the number of capillaries supplied by a single arteriole is so great that the total cross-sectional area available for the flow of blood is increased. Therefore, the pressure of the blood as it enters the capillaries decreases.
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Blood flowing slowest where the cross-sectional area is highest can be compared to what?
- a river
- it flows more slowly as it becomes wider
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What increases every time a blood vessel branches?
cross-sectional area
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once a capillary bed is crossed, what happens to the cross-sectional area and velocity?
the cross-sectional area decreases as the vessels merge and velocity again increases
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junction where two vessels split
bifurcation
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junction where 2 vessels unite
anastomoses
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what useful purpose do anastomoses serve?
provide alternate routes for blood
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term used to describe an alternate route of circulation involving anastomoses
collateral circulation
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What are arteries that do not anastomose called?
end arteries
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What is an example of an end artery?
coronary arteries
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Where is blood velocity highest?
larger diameter vessels
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Where is blood velocity lowest?
capillaries
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refers to the amount of blood that passes through a vessel in a given period of time
blood flow
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what determines the rate of blood flow?
blood pressure and resistance
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the pressure exerted by blood on the walls of blood vessels
blood pressure
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blood flows from regions of ________ blood pressure to regions of _________ blood pressure.
higher, lower
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blood pressure differences are related to ___________
resistance
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the opposition to blood flow as a result of friction between blood and the walls of blood vessels
resistance
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Resistance increases with.....
- viscosity
- blood vessel length
- decreasing blood vessel diameter
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primary cause of blood flow resistance
friction between blood and the walls of the blood vessels
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blood pressure is considerably ________ in veins than in arteries
lower
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Why are one way valves so important in the veins?
to prevent back flow since the pressure is considerably lower in the veins than in the arteries
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venous valves are most important in the...
distal extremities
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What structures outside of the cardiovascular system are important in moving blood through the veins?
skeletal muscles
their action helps force blood through the veins
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How is the pressure gradient for systemic circulation determined?
it's the difference between the pressure in the aorta and the pressure in the vena cava
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Is the pressure gradient in the vena cava ever zero?
no, pressure in the vena cava is low, but there is alway pressure
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where is the cardiovascular center?
medulla
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function of the cardiovascular center
influences heart rate and exercises vasomotor control over the diameters of blood vessels
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term for the cardiovascular center's influence over the diameter of blood vessels
vasomotor control
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the vasomotor system is acted upon by the _____________ nervous system
autonomic nervous system
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the sympathetic nervous system __________the blood vessels, which makes blood vessels _________, which __________ blood pressure
- constricts
- smaller
- increases
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the parasympathetic nervous system ______________the blood vessels, which makes the blood vessels _____________, which _________ blood pressure
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How does the vasomotor system cause peripheral resistance to increase?
by constricting the arterioles and the precapillary sphincters through vasoconstriction
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How many sources provide input to the cardiovascular center?
4
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What are the 4 sources that provide input to the cardiovascular center?
- higher brain centers (cerebral cortex, and hypothalamus)
- proprioceptors
- baroreceptors
- chemoreceptors
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someone suddenly arising from recumbent position to standing position causes what?
what causes this to occur?
an immediate increase in heart rate
proprioceptors in joints interpreted the change in body position and sent message to the CV center
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2 higher brain centers that provide input into the CV center
- hypothalamus
- cerebral cortex
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2 autonomic responses that influence the CV center
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Where are proprioceptors located? What do they do?
- joints
- interpret body position
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recumbent position
lying down
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blood pressure in the recumbent position is....
lower than in the standing position
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If in the recumbent position, what might activate the proprioceptors?
standing up
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Where are baroreceptors located?
carotid artery and aorta
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how do baroreceptors function?
sense pressure changes and influence the nervous system to adjust the pressures accordingly
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where are chemoreceptors located?
in the carotid and aortic arteries
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what do chemoreceptors do?
monitor levels of oxygen, carbon dioxide, and hydrogen ions (pH)
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Due to chemoreceptors, an increase in carbon dioxide would result in.....
an increase in blood pressure
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3 intrinsic chemicals in the blood that can influence blood pressure
- epinephrine (increases rate and force of heart contractions)
- antidiuretic hormone (vasoconstriction in the kidneys)
- histamine (vasodilation)
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intrinsic
found within
Situated within or belonging solely to the organ or body part on which it acts.
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2 main circulatory routes in the body
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hepatic portal is part of the....
systemic route
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what organs does the hepatic portal originate from?
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where does the hepatic portal system cary nutrient rich venous blood to?
the liver
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2 arterial components of the pulmonary route
- pulmonary trunk
- pulmonary arteries (left and right)
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how many pulmonary veins are there?
4 (2 per lung)
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What is the largest artery in the body?
aorta
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5 portions of the aorta
- ascending aorta
- arch of the aorta
- descending aorta
- thoracic aorta
- abdominal (dorsal) aorta
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10 major arteries that branch off the directly from the aorta in sequence
- coronary
- brachiocephalic (right only)
- left common carotid (left only)
- left subclavian (left only)
- celiac trunk
- superior mesenteric
- renal arteries
- gonadal
- inferior mesenteric
- iliac
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How many brachiocephalic arteries are there?
1 (on rt side of body only)
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3 arteries that form at, or close to, the terminus of the brachiocephalic artery?
- common carotid
- right subclavian
- vertebral
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Name in sequence 4 major arteries leading from the subclavian arteries to the hand
- axillary (arm pit)
- brachial (arm)
- radial (thumb side)
- ulnar (pinky side)
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common carotid arteries bifurcate (split) to form
- external carotid
- internal carotid
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what vascular structure do the vertebral arteries terminate in? what is it called where they come together?
- basilar artery
- an anastomosis
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vascular structure which basilar artery and internal carotid arteries feed into
circle of Willis
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arteries that comprise the cephalic trunk
- common hepatic
- left gastric
- splenic
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arteries that formed from the bifurcation of the dorsal (abdominal) aorta
right and left iliac
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5 major arteries leading from the dorsal (abdominal) aorta to the foot
- iliac
- femoral
- popliteal
- tibial
- peroneal (fibular)
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Do veins generally have the same name as arteries?
yes
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veins that accompany arteries and have the same names are called
venae comitantes
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Is venous systemic blood really blue?
no
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largest vein in the body
greater saphenous
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2 major portions of the vena cava
- superior vena cava
- inferior vena cava
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into what veins do the external jugular veins flow?
subclavian
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subclavian veins meet the internal jugular veins to form__________
brachiocephalic vein
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5 major veins leading from the right hand to the brachiocephalic vein
- cephalic
- basilic
- brachial
- axillary
- subclavian
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6 major veins leading from the foot to the inferior vena cava
- dorsal pedis
- peroneal
- tibial
- popliteal
- femoral
- iliac
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How many major veins comprise the venous portal system? Name them.
- 4
- hepatic portal
- gastric
- splenic
- mesenteric
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What is an aneurysm?
weakened section of a vessel that balloons outward
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What is the danger of having an aneurysm?
it may rupture causing exsanguination (abdominal aortic aneurysm) or stroke (cerebral arteries)
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What is medical term for stroke?
cerebrovascular accident (CVA)
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Medical term for high blood pressure?
hypertension
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What does CAD stand for?
Coronary artery diesease
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What is coronary artery disease (CAD)?
insufficient blood supply to the myocardium caused by atherosclerosis
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Another term for atherosclerosis
arteriosclerosis
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accumulates in the atherosclerotic blood vessels
atherosclerotic plaque
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excessive plaque causes
- blockages
- it accumulates in the lumens of the coronary arteries and restricts blood flow
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coronary arterial narrowing in excess of 75% produces...
angina pectoris
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what is angina pectoris
ischemia (reduced blood flow) to coronary arteries causing chest pain
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nonsurgical treatments for CAD
- smoking cessation
- decrease dietary fats
- antihypertensives (reduce blood pressure)
- statins
- nitroglycerin (vasodilator)
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acronyms for 2 surgical procedures for treating CAD
- CABG (coronary artery bypass grafting)
- PTCA (percutaneous transluminal coronary angioplasty)
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CABG (coronary arterial bypass grafting) is
portion of a blood vessel removed from another area of the body is grafted onto a coronary artery to bypass an obstruction
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What is PTCA (percutaneous transluminal coronary angioplasty)? What is it often followed by?
balloon catheter insertion into obstructed artery, balloon is inflated and often pulled across the obstruction flattening plaque against luminal wall.
insertion of a mesh stent
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what blood pressure reading puts a person in hypertensive category?
150/100
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3 causes of high BP
- atherosclerosis
- kidney disease
- obesity
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type of hypertension associated with old age
Is is bad?
essential hypertension
no
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rare but sudden episode of severe coronary vasospasm, thought to be cause of adult sudden death, often associated with extreme stress and atherosclerosis
Prinzmetal's variant
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thrombus (clot) forms typically in lower legs, sometimes carried to the lungs or heart
deep vein thrombosis
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when a blood clot forms in lower leg it causes...
thrombophlebitis
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2 possible results of deep vein thrombosis
- pulmonary embolism
- coronary embolism
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another name for a clot
thrombus
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thrombus that travels in the bloodsteam
embolism
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thrombus that travels to the lungs
pulmonary embolism
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thrombus that travels to the coronary arteries
coronary embolism
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treatments for embolic conditons
fibrinolytics (break down clots)
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name a fibrinolytic
streptokinase
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another name for a faint
syncope
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what kind of response is syncope?
parasympathetic (SLUD)
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ischemia
decreased blood flow
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syncope caused by...
parasympathetic vasodilation and lowering of BP which results in temporary ischemia (decreased blood flow) of the arteries within the brain
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