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what is the difference between muscular arteries and elastic arteries?
- Muscular arteries contain more smooth muscle in their tunica about 3/4 of their mass is muscle.
- Elastic arteries have less smooth muscle, tend to be longer and have the largest diameter
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What are conducting arteries?
Arteries that conduct blood from the heart to medium sized, more muscular arteries
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what are distributing arteries?
Arteries that branch out and distribute blood to organs
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What are arterioles?
Arterioles are small arteries
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What key role to arterioles play in the circulatory system?
They regulate blood flow to capillaries
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What are capillaries?
Capillaries are the smallest blood vessels.
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What is the importance of capillaries?
They are the exchange vessels of the body. They exchange substance between the blood and interstitial fluid, they are found nearly on every cell of the body
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what does micro circulation mean?
the blood circulation of the smallest blood vessels
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describe the arrangement of a typical capillary bed
a network of 10-100 capillaries that arise from a single metarteriole
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What is the function of a sphincter?
The function of a pre capillary sphincer is to regulate the flow of blood though capillary beds
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what is the role of throughfare channels?
To provide a direct route for blood from an arteriole to venule, thus bypassing capillaries
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what does vasomotion mean?
is the intermittent contraction and relaxation of smooth muscle in the metarterioles and pre-capillary muscles
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Describe the 3 different types of capillaries
- 1-continuous capillaries, straight tubes.found in central nervous system, lungs and skin.
- 2-fenestrated capillaries, they have little pores.they are found in kidney, ciliary process and ventricles of the brain.
- 3-Sinusoid, wider and more winding then other capillaries. usually have larger fenestrations and incomplete or absent of basement membrane
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what are venules?
venules are little veins, with thin walls
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What formed elements uses these vessels to leave the blood?
WBC use these vessels to leave the blood
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what vessels act as blood reservoir?
systemic veins and venules
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what two factors are important for determining where cardiac output goes?
- 1-vascular resistance
- 2-pressure difference
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Define blood flow
Blood flow is the volume of blood that flows through any tissue in a given time ml/min
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Define velocity
the speed of blow flow in cm/sec
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what is the relationship of cross-sectional are to velocity?
the greater the cross-section the slower the blood flows. Capillaries have the slowest blood flow
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What is the relationship of blood flow and resistance?
The more resistance the less blood flow
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Define blood pressure.
The hydrostatic pressure of blood against the wall of a blood vessel
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What is MABP
its diastolic + 1/3(systolic-diastolic)
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what is the relationshBP to distance from the ventricle
The more distance has the more pressure increases.
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name two important factors that influence blood pressure
- 1- cardiac output and
- 2- vascular resistance
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Define vascular resistance
the opposition to blood flow due to the friction between blood and the walls of blood vessels
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What three factors determine resistance in blood vessels?
- 1-size of lumen
- 2-blood vescocity
- 3-total blood vessel lengh
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which of the three factors that determine blood resistance can your body modify?
The size of lumen
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Which of the three factors that determine blood resistance is fairly constant?
blood vescocity
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Define vescocity
the thickness of blood, usually determines by ratio of RBC to blood plasma
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What factors increase the viscosity of the blood?
- 1-number of RBC
- 2-dehydration
- 3-burns
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what factors decrease the viscosity of blood?
- 1-anemia a decrease of RBC
- 2-hemorrage,
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what is polycythemia?
a decrease of RBC
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how can one increase the total vessel lengh in the body?
by putting on fat. 2.2 lbs of fat=200 miles of new blood vessels
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what is the relationship between the diameter of blood vessel and resistance?
The greater the diameter the less resistance to the vessels
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Where is more resistance found in the circulatory system?
arteries, capillaries and venules
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what is systemic vascular resistance?
The resistance created by systemic blood vessels
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what is the relationship of arteriorles and systemic vascular resistance?
arterioles control flow of SVR to blood flow and pressure to particular tissues by changing their diameter
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what center controls blood pressure and flow?
the cardiovascular center
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where does the cardiovascular center get input from?
- 1-cerebral cortex
- 2-somatic receptors, like chemoreceptors and baroreceptors
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what nerves carry the output for the cardiovascular center?
- 1-vagus nerves
- 2-cardiac accelerator nerve
- 3-vasomotor nerve
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what other factors can control blood pressure?
hormones and autoregulation from physical and chemical changes
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what is autoregulation?
the ability of tissue to automatically adjust to its blood flow to match its metabolic demands
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what is skeletal pump?
the skeletal muscle contractions that drive venous blood toward the heart
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what is the respiratory pump?
the diaphragm's up and down movement which causes veins to compress
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Describe three ways that exchange can take place between capillaries and tissues
- 1-diffusion
- 2-transcytosis
- 3-bulk flow
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name some substances that move in and out of the blood through diffusion
o2, CO2, hormones
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name some of the substance that move in and out of the blood though transcytosis
insulin, antibodies, large lipid-insolubels
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name some of the substance that can move in and out of blood though bulk flow
large number of ions
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what is transcytosis?
the movement of substances via pinocytic vesicles
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what is bulk flow?
a passive process, driven by change in pressure across capillaries
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what is the most important way exchange take place?
diffusion
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which of the three ways is important for regulating the relative volume of blood and interstitial fluid?
bulk flow
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what forces promote filtration?
blood hydrostatic pressure and interstitial fluid osmotic pressure
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what forces promote reabsorption?
blood colloidal osmotic pressure(BCOP) and Interstitial fluid hydrostatic pressure
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