Term
| List the layers of a blood vessel |
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Definition
1. Tunica adventitia
2. Tunica media
3. Tunica intima
4. Lumen |
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Term
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Definition
1. Outer most layer
2. Collagen fibers for protection & anchoring vessles |
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Term
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Definition
1. Middle layer
2. Smooth muscle & elastic fibers
3. Changes diameter of vessels
4. Thicker in arteries than veins |
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Term
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Definition
1. Inner most layer
2. Simple squamous epithelium called endothelium
3. Cells fit like tiles on a floor
4. Minimizes friction with blood |
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Term
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Definition
1. Central space
2. Larger in a vein than in an artery
a. Because of the low pressure in veins |
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Term
| Structual Differences Among Vessels |
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Definition
i. Reflect higher pressures
ii. Need for close contact
1. Capillaries & tissues
2. Need for diffusion
iii. Veins return blood to the heart
1. Lower pressure
2. Often against gravity |
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Term
| List the different types of Arteries |
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Definition
1. Elastic Arteries
2. Muscular Arteries
3. Arterioles
4. Capillaries |
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Term
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Definition
i. Thick walled arteries near the heart
ii. Large in diameter & elastic
iii. Expand when ventricles contract then recoil to maintain diastolic BP |
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Term
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Definition
i. Diameter 10mm- 0.3mm
ii. Elastic arteries give way to muscular arteries
iii. Smaller arteries in the rest of the body
iv. Not as stretchy as elastic arteries
v. Smooth muscle in their tunica media |
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Term
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Definition
i. Small arteries, 0.3mm-10um
ii. Control how much blood is going to a tissue
iii. Use pre-capillary sphincter muscle to nearly shut off or increase blood supply
1. Blushing |
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Term
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Definition
i. Microscopic, are smallest vessels
ii. Walls only have tunica intima
iii. Very thin walled
iv. RBC’s pass single file
v. Site of exchange of O2 & nutrients
vi. Arteries & veins only transport system |
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Term
| List the different types of capillaries |
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Definition
1. Continuous
2. Fenestrated
3. Sinusoidal |
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Term
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Definition
a. Skin & muscles
b. Most common
c. Uninterrupted lining of endothelial cells
d. Very small gaps between cells allow fluids to leak through |
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Term
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Definition
a. Walls of these capillaries have pores
b. Covered with a very thin membrane
c. Permits greater permeability of fluids & small molecules
d. Found in areas where absorption takes place (intestines) |
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Term
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Definition
a. Very leaky capillaries
b. Found in liver, bone marrow, lymph tissue
c. Large holes in lining that permits leakage of molecules or cell
d. Broken by other cell types like microphages
e. Blood flow is very slow |
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Term
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Definition
i. Like arteries but contain un-oxygenated blood
ii. Very porus to permit the movement of WBC & fluid |
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Term
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Definition
i. Opposite if arteries
ii. Usually contain un-oxygenated blood
iii. Contain back-flow valves
iv. Low blood pressure |
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Term
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Definition
| 1. Actual volume of blood flowing through a vessel, organ, or body per unit of time, ml/min |
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Term
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Definition
| 1. Force per unit area exerted by the blood on the walls of a blood vessel, mmHg |
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Term
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Definition
1. Opposition to flow, a measure of the amount of friction the blood encounters as it flows through vessels
a. Larger the vessel the less the resistance
b. Greatest resistance in capillaries |
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Term
| What are the three sources of resistance |
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Definition
1. Blood Viscosity
2. Total Blood Vessel Length
3. Blood Vessel Diameter |
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Term
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Definition
a. Thickness of the blood
b. Like the difference between molasses & water
c. Thicker the blood, the greater the resistance
d. Relatively constant |
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Term
| Total Blood Vessel Length |
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Definition
a. Longer the length of a vessel the greater the resistance- increase in pressure
b. Total is relatively constant
c. Length does change as blood travels through the system
i. Greatest at output side
ii. Zero at input side |
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Term
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Definition
a. Not constant
b. Fluid close to the walls encounter more resistance
i. Parabolic velocity profile
1. Flow faster in the center
c. Smaller vessels have more resistance because more fluid contracts the side
d. Capillaries have the most resistance because they have smallest diameter
e. Large vessels near the heart have very little resistance due to the blood vessel diameter |
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Term
| Flow is directly related to blood pressure |
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Definition
1. More the pressure the greater the flow
2. Less the pressure the less the flow |
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Term
| Flow negatively related to resistance |
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Definition
1. More resistance the slower the flow
2. Less resistance greater the flow |
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Term
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Definition
1. A fluid pumped through a closed system is under pressure
2. Closer the pump, greater the pressure
3. Heart creates blood flow
4. Resistance to blood flow generates blood pressure
a. Pressure can be generated without pressure
5. Blood moves down a pressure gradient from high pressure to low pressure
6. Highest near the output side of the heart near aortic arch
7. Declines to zero at the input side of the heart- right atrium |
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Term
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Definition
i. Depends on two factors
1. How much the elastic arteries can be stretched
2. volume of blood being forced through them
ii. Heart beats so blood pressure in the arteries is not constant
iii. When the ventricles contract they expel blood
iv. Blood streches the aorta and pressure in the aorta peeks
v. Systolic pressure in the aorta ~120 Hg mm
vi. Blood flows because the pressure in the distal vessels is less than the proximal vessels
vii. During diastole:
1. Semilunar valves close to prevent back flow
2. Elastic arteries recoil and maintains some pressure on the blood
3. Blood volume does lessen
viii. Minimum blood pressure in the aorta ~70-80 Hgmm
ix. Potential energy in the aorta is released as kinetic energy
x. Energy maintains blood flow during diastole |
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Term
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Definition
i. Large average pressure gradient aorta to arteroles ~60mm Hg
ii. Blood pressure drops to ~ 40 mmHg
iii. By the end of the capillary bed the pressure drops to 20mmHg |
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Term
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Definition
i. Blood pressure is constant so blood flow is steadily, it doesn’t pulse
ii. The magnitude of the blood pressure declines due to decreasing resistance
1. Decreasing length
2. Increasing diameter
iii. Pressure gradient of 20mm Hg |
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Term
| Factors aiding venous blood return |
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Definition
1. Respiratory pump
a. Inhaling increases abdominal pressure squeezing abdominal blood vessels and forces blood to the heart
b. Valves in the veins prevent backflow
c. Simultaneously the pressure in the thoracic cavity decreases and the veins expand allowing more blood to enter them
2. Muscular pump
a. Skeletal muscle contract and relax and they milk the blood towards the heart
b. Most important of these two pumps |
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Term
| Blood pressure can be varied in three ways |
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Definition
i. Change cardiac output
ii. Change the peripheral resistance (change in diameter)
iii. Change blood volume
iv. Neural ways to change peripheral resistance
1. Alter blood distribution between organs to respond to specific demands
2. Alter blood vessel diameter to increase or decrease blood pressure |
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Term
| Neural controld for peripheral resistance |
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Definition
1. Role of Vasomotor center
2. Baroreceptor initiated reflexes
3. Chemoreceptor reflexes |
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Term
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Definition
1. Located in the medulla
2. Controls blood vessel diameter
3. Transmits APs to the smooth muscle of the arterioles
4. Muscles are always in a slight state of contraction |
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Term
| Baroreceptor initiated reflexes |
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Definition
1. Pressure receptors
2. Locations:
a. Internal carotid arteries
b. Aorta
c. Most of the large elastic arteries
3. Increased arterial blood pressure causes these receptors to send AP to the vasomotor center
4. A decrease in blood pressure cause the opposite reaction
5. System functions to protect against rapid changes in blood pressure
a. Stand up too quickly |
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Term
| Chemoreceptor initiated reflexes |
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Definition
1. when O2, & CO2 levels rise & pH decreases
a. Chemoreceptors in the aortic arch & neck send APs to the vasomotor center
b. Vasoconstriction occurs
2. Increased blood pressure speeds up the flow of blood to the heart & lungs |
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Term
| List the Chemical modifications of peripherial resistance |
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Definition
1. Epinephrine & Norepinphrine
2. Angiostein II
3. Antidiuretic hormone
4. Nitric Acid
5. Alcohol |
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Term
| Epinephine & Norepinephrine |
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Definition
1. Secreted by adrenal medulla
2. Part of the fight or flight response
3. Effect the heart by increasing cardiac output
4. Causes vasoconstriction in arterioles
5. Vasodilatation in large veins, cardiac and skeletal muscle
6. Overall increases blood pressure and the rate of delivery |
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Term
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Definition
1. Effects peripheral resistance
2. Causes vasoconstriction in arterioles
3. Increases blood pressure |
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Term
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Definition
1. Stimulates the kidneys to conserve water
2. Causes a relative increase in blood volume
3. Effects peripheral resistance when there is extreme blood loss
4. Causes vasoconstriction in arterioles |
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Term
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Definition
1. Causes vasodilatation
2. Very short lived
3. Released in response to high rates of blood flow
4. May be a major factor in maintaining blood pressure |
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Term
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Definition
1. Causes a drop in blood pressure
2. Inhibits antidiuretic hormone release
3. Depresses the vasomotor control center and causes vasodialation
a. Warm feeling, and blushing |
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