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Diastolic pressure
lowest arterial pressure during diastole (heart relaxation)
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What factors influence blood pressure?
- Hemorrahaging
- Dehydration
- Edema
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What mechanisms regulate the movement of fluids between capillaries and interstitial spaces (CHP, BCOP)?
- Net hydrostatic pressure tends to push water and solutes out of capillaries and into interstitial fluid: NHP=CHP-IHP
- Net colloid osmotic pressure tends to pull water and solutes into a capillary from the interstitial fluid: NCOP=BCOP-ICOP
- NHP and NCOP oppose eacher and the larger force wins
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Blood Flow
Is the volume of blood that flows through any tissue in a given time period.
Blood flow is equal to CO=HRxSV
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How does blood flow?
From regions of high pressure to regions of lower pressure
The greater the pressure difference, the greater the blood flow
The higher the resistance, the smaller the blood flow
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Blood Pressure (BP)
- The hydrostatic pressure exerted by blood on the walls of a blood vessel
- Generated by the contraction of the ventricles
- Highest in Aorta and large systemic arteries
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Systolic pressure
highest arterial pressure attained during systole (heart contraction. Lup
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Tunica Externa
- Fibrous connective tissue
- Provide support and elasticity
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Tunica Media
- Smooth muscle fibers
- Elastic fibers that allow for extreme amounts of pressure
- Stretch and go back
- cause changes in blood vessel diameter
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Tnica interna (intima)
- Endothelium lining inside of blood vessel
- Connective tissue
- Touches the blood
- continuous with endocardium in heart
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Arteries
- Thicker tunica media
- more elastic fibers
- built to resist pressure
- always look circular
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Veins
- contain valves
- tinner tunica media
- look flattened
- larger than arteries
- collect blood from all the tissues and organs and return it to the heart
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How are arteries classified?
Elastic (conducting) large vessels wihich transport large volumes of blood away from the heart
Muscular (distribution) transport blood to skeletal muscle and internal organs
Arterioles resistance vessels
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Capillaries
- Most numerous and smallest vessels
- Exchange vessels
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Capillary Beds
- function as an interconnected network
- exchange of materials
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Precapillary sphincter
- regulate blood flow into capillary bed
- vasomotion-cyclic contraction and relaxation of sphincter
- flow is based on tissue need
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Anastomosis
interconnections between arteries and veins or ateries to arteries and veins to veins
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How do oxygen, carbon dioxide, and water move between tissues and capillary beds?
Oxygen and nutrients diffuse from blood into interstitial fluid and into cells
Carbon dioxide and wastes diffuse from cells into interstitial fluid and into blood
Water is exchanged by osmosis
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How are veins classified?
Venules-collect blood from capillary beds and are the smallest venous vessels
Medium-sized veins-range from 2-9mm
Large veins-include superior and inferior vena cava
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Why do veins have valves?
BP in the venules and medium veins is so low that it cannot oppose gravity. Blood wants to pool in lower extremitites.
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Arterial blood pressure (BP)
- pressure from aorta to arteroles (100-35mmHg)
- maintains blood flow through the capillary beds
- rises during ventricular systole and falls during ventricular diastole
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Capillary hydrostatic pressure (CHP)
pressure within capillary beds (35-18mm Hg)
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Venous pressure
the pressure within the venous system (18mmHg)
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MAP
average blood pressure in arteries
MAP = DP+1/3(systolic BP-diastolic BP)
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Resistance
resistance of the cardiovascular system opposes the movent of blood
the result of friction between blood and walls of the blood vessels
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What does resistance depend on?
- Total vessel length
- vessel diameter
- blood viscosity
- turbulence
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Total peripheral resistance (TPR)
The sum of all vascular resistance
Major function of arterioles is to control this by vasoconstriction and vasodilation
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Peripheral resistance
the resistance of the arterial system
for blood to flow the pressure gradient must be great enough to overcome this
Flow = P/R
- Increase in pressure = increase in flow
- Increase in resistance = decrese in flow
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Capillary Exchange
- Movement of substances from blood in the capillaries to interstitial space
- Assists in the transport of lipids and tissue proteins
- accelerates the distribution of nutrients
- carries toxins and other chemical stimuli to lymphoid tissues
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Diffusion
- Movement from an area of high concentration to an area of low concentration
- rapid exchange of respiratory gases O2 and CO2
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Filtration
- pressure-driven movement of fluid and solutes from the blood capillaries into interstitial fluid
- circulatory system will push material out to the tissues
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Reabsorption
- pressure-driven movent from interstitial fluid into blood capillaries
- pushes material into bloodstream
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What promotes filtration?
Blood hydrosatic pressure (CHP)
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What promotes reabsorption?
Blood colloid osmotic pressure (BCOP)
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Net filtration pressure
- the balance between CHP and BCOP
- which one is bigger determines which one moves
NFP=CHP-BCOP
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Hemorrhaging
- blood volume and pressure drops
- CHP lowers NFP fluid moves from tissues into blood
- known as recall of fluids
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Dehydration
plasma volume decreases, increases BCOP fluid is recalled from tissues
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Edema
- abnormal accumulation of interstitial fluid and one happens
- CHP rises-increases in arterial, venous, or total circulatory pressure
- BCOP declines-capillary damage, starvation
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Venouse pressure and venous return
Venous pressure determines venous return which has an impact on CO
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Muscular compression
- the contractions of skeletal muscles near a vein compress it
- Fainting or syncope
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Repiratory pump
- as inhale your thoracic cavity expands and pressure within the pleural cavity decreases. This drop in pressure pulls blood into the IVC and atrium from smaller veins
- Area of high pressure to an area of low pressure
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Autoregulation accelerates the blood flow how? And what performs this?
Vasodilators and local vasoconstrictors(prostaglandins, thromboxanes)
- Decreased tissue O2 levels or increased CO2 levels
- Generation of lactic acid
- Release of nitiric acid
- Rising K+ or H+ concentrations in interstitial fluid
- Local inflammation
- Elevated temperature
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Neural mechanisms do what?
Adjust CO and PR to maintain vital organ blood flow
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What are the medullary cneter of regulatory activity?
- Cardiac centers
- Vasomotor centers
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Cardiac centers
- cardioacceleratory-sympathetic
- cardioinhibitory-parasympathetic
- Control HR, contractility-->blood flow, BP
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Vasomotor centers
- Vasocontriction-via adrenergic release of NE-cause more resistance when there is a change
- Vasodilation-via direct or indirect release of NO-can have cnetral or local dilation
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Baraoreceoptor
- influence cardiac centers or vasomotor center
- monitor pressure
- in walls of expandable organs
- also located: Corotid arteries-corotid sinus, Arch of aorta-aortic sinus, and walls of the rt. atrium
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Chemoreceptor reflexes
- Monitor O2 levels and CO2 concentration
- Located in: Carotid arteries-carotid bodies and Aorta-aortic bodies
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Hormones that play a part in cardiovascular regulation
- Antidiuretic homone-released in response to decreased blood volume(against pee)
- Angiotensin II-releasd in response to a fall in blood pressure(released by kidneys to red bone marrow)
- Erythropoietin-released if BP fall or O2 levels are abnormally low
- Natriuretic peptides-released in response to excessive right atril stretch(increase pee and gets rid of sodium)
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What are the arteries of the brain?
- Common carotid arteries
- External caratid artery
- Internal carotid artery
- Ophthalmic artery
- Anterior cerebral artery
- Middle cerebral artery
- L/R vertebral arteries
- Basilic artery
- Circle of Willis
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Comon carotid arteries
ascend the neck and divide into External and Internal carotids
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External carotid
supplies the neck, esophagus, pharynx, larynx, lower jaw, and face(nothing with brain)
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Internal carotid
- Enter into carotid foramen and delivers blood to the brain and divides into ophthalmic artery, anterior cerebral artery, middle cerebral artery
- Vertebral
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Circle of Willis
- Anastamosis
- Guarantees blood supply to the brain(blood will have an alternate route to go through if there is a block)
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Hepatic Portal System
- Blood leaving the capillaries supplied by the celia, superior, and inferior mesenteric arteries flows into this.
- Centralizes blood from the GI tract
- Nutrient procession
- Detoxification
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What is the only digestive organ that drains directly into the IVC?
Liver
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Fetal Circulation
- 1. Umbilical cord
- 2. Unbilical arteries(deoxygenated blood and waste the the placenta)
- 3. Unbilical vein(oxygenated blood is returned to the fetus)
- 4. Drains into Hepatic portal vein and Ductus venosus in the fetal liver
- 5. Drains into the IVC
- 6.Foramen ovale-hole between R and L atrium
- 7. Ductus arteriousus connects to Aorta
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