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24 Cards in this Set
- Front
- Back
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VESSEL FUNCTION
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form a circular path to carry blood between the heart and tissues
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TWO (and a half) SYSTEMS (CIRCUITS) OF BLOOD VESSELS
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A. PULMONARY CIRCUIT (CIRCULATION):
1. blood from heart to lungs, from lungs to heart 2. job: remove CO2 from blood, pick up O2 from lungs B. SYSTEMIC CIRCUIT (CIRCULATION): 1. blood from heart to body, from body to heart 2. job: take O2 to tissues, remove CO2 from tissues C. HEPATIC PORTAL CIRCULATION: 1. Blood from digestive tract organs to liver 2. Job: carry nutrient-rich, O2-poor blood to liver for filtration before it returns to the general circulation. |
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TYPES OF BLOOD VESSELS AND THEIR STRUCTURES
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A. HEART -> ARTERIES -> ARTERIOLES -> CAPILLARIES -> VENULES ->
VEINS -> HEART |
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LUMEN
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space inside blood vessels, blood flows thru here
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LAYERS OF THE VESSEL WALLS
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1. TUNICA INTIMA (INTERNA): near lumen, helps reduce friction
* ENDOTHELIUM: (continuous with endothelium of heart) 2. TUNICA MEDIA: middle layer, thickest layer a. circular smooth muscle, ELASTIN (in arteries) b. symp. N.S. stimulates vasoconstriction to regulate blood flow and BP 3. TUNICA ADVENTITIA: outermost layer attaches BV to tissues * VASA VASORA: bv’s that carry blood to the blood vessel wall if the BV has a thick wall |
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ARTERIES AND ARTERIOLES
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carry blood away from heart
1. thick tunica media, lots of elastin 2. most carry oxygenated (red) blood (exceptions: PULMONARY A. and UMBILICAL AA. – carry deoxygenated - blue blood) 3. ANEURYSM: bubble in a weak artery wall |
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VEINS, VENULES, AND SINUSES
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dural, hepatic and coronary):blood to heart
1. VEIN WALLS a. all three layers, but thinner than in arteries b. less pressure than arteries c. hold more blood than arteries (65% of blood at a time) - due to wide diameter 2. most carry deoxygenated (blue) blood. (exceptions: PULMONARY VV. and UMBILICAL V. – carry oxygenated-red blood) |
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CAPILLARIES
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microscopic in size- intermediary to aa, vv
1. ENDOTHELIUM only, FENESTRATED, thin walls, allow exchange of materials with tissues, decrease blood pressure in BV 2. smallest, most numerous BV (length encircles earth 2.5x) size-> SLOW BLOOD VELOCITY: RBC's pass thru in single file, allows time for material exchange 3. tissue's capillary density varies with metabolic activity a. kidney, liver, skeletal m. HAVE LOTS b. CNT: FEWER c. epidermis, lens, cornea: NONE |
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CAPILLARY BEDS
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interwoven networks of 10-100 CAPILLARIES
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ANASTOMOSES
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alternate blood routes; allow blood passage even if clot blocks one way
to tissues 1. arterial anastomosis: between arteries of same area 2. venus anastomosis: between veins of same area 3. arteriovenosus anastomosis: between a & v (vascular shunt) |
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BLOOD FLOW/VELOCITY
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ml/min thru an area VELOCITY = CO
*VELOCITY: fastest in aorta decreases to capillaries(slowest) then increases in veins on way to heart 1. VELOCITY AFFECTED BY BP: increase BP, increase VELOCITY 2. VELOCITY AFFECTED BY PERIPHERAL RESISTANCE (PR): inc. resistance, decreases velocity. Increased PR results from: a. friction: as branching/length of vessels inc., surface area and friction inc. *capillaries are highly branched (small), SLOWEST flow, & most exchange with tissues b. inc. VISCOSITY (thickness) of blood |
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NET EXCHANGE AT CAPILLARY BEDS WITH INTERSTITIAL FLUID:
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Net Filtration Pressure = NFP= (HPc + OPif) - (OPc + HPif)
= (forces out of capillaries) - (forces into capillaries) 1. REGULATED BY TWO TYPES OF PRESSURES a. HYDROSTATIC PRESSURE: fluid pressing against a vessel wall -CAPILLARY HYDROSTATIC PRESSURE (HPc) pr. in cap. forcing fluids out of caps: varies from arterial to venous ends of cap bed*arteriole end: HPc = 35 mmHg out of cap. *venule end : HPc = 17 mmHg out of cap. -INTERSTITIAL FLUID HYDROSTATIC PR. (Hpif) pr in IF forcing fluid into capillaries: negligible due to removal of fluid by lymphatic system *Hpif = 0mmHg into cap. b. OSMOTIC PRESSURE: due to large particles (proteins) that attract water -CAPILLARY OSMOTIC PRESSURE (Opc) pr drawing fluid into cap due to lg plasma proteins that could not be filtered out of cap *OPc = 26mmHg into cap. -INTERSTITIAL FLUID OSMOTIC PRESSURE (OPif) pr drawing fluid out of cap to dilute protein in IF (lo [prot.]) *OPif = 1mmHg out of cap. |
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NET FILTRATION PRESSURE
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: pr driving blood fluid loss
NFP = pressures out of capillaries - pressures into capillaries pr out: (arteriole end) HPc + OPif=35 + 1 = 36 mmHg (venule end) HPc + OPif = 17 + 1 = 18 mmHg pr in: same for arteriole and venule ends: HPif + OPc = 0 + 26 = 26 mmHg NFP arteriole end = 36 mmHg - 26 mmHg = 10 mmHg out of capillaries NFP venule end = 18 mmHg - 26 mmHg = -8 mmHg out (or +8 mmHg into capillaries) |
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VEINS, VENULES, AND SINUSES CONTINUED...
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3. VEINS ARE ADAPTED TO GET BLOOD BACK TO HEART
a. heart doesn't help with VENOUS RETURN and little pressure remains in blood as it enters veins b. large diameter, little resistance to blood flow c. VALVES in wall prevent back flow d. SKELETAL MUSCLE MILKS V.: muscular pump e. vasoconstriction of tunica media (smooth muscle) of veins f. DIAPHRAGM CONTRACTION: respiratory pump * contract during inhalation: dec. thoracic pr, inc. abdominal pr; blood moves toward heart from legs |
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BLOOD PRESSURE
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hydrostatic pressure blood exerts against BV wall (mmHg)
1. directly affected by: Blood Volume, CO and PR a. BLOOD VOLUME - increase Vol, increase BP b. CARDIAC OUTPUT-volume of blood out of 1 vent. in 1 min.= vol/min -inc. CO, inc. BP c. RESISTANCE TO BLOOD FLOW (PR): inc. resistance, inc. BP |
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REGULATION OF BLOOD PRESSURE
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SHORT TERM (remember, CO = HR x SV)
1) BARRORECEPTORS IN AORTA AND CAROTID SINUS -hi BP -> medulla-> PSNS-> vasodilation -> dec. HR, CO, BP *combats change in BP due to change in posture 2) CHEMORECEPTORS IN AORTA AND CAROTID BODIES -hi CO2/lo pH/ lo O2 -> medulla -> SYNS -> vasoconstriction -> inc. HR, RR, BP * works in extreme conditions 3) HORMONES: EPINEPHRINE, NOREPINEPHRINE, ADH, ANF -stress -> SYNS -> EPIN/NOREPIN. from adrenal medulla -> vasoconstriction -> inc. BP, CO -lo blood volume -> hypothalamus -> Antidiuretic Hormone -> inc. fluid retention, blood vol, BP -hi BP -> heart releases Atrio Naturietic Factor -> vasodilation, inc kidney excretion -> dec. blood vol, BP |
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MEASURING ARTERIAL BP
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measured in mmHg
a. BP varies with pumping action of VENTRICLES 1) greatest during v. systole = SYSTOLIC PRESSURE 2) lowest during v. diastole = DIASTOLIC PRESSURE b. SPHYGMOMANOMETER: inflatable cuff c. STETHOSCOPE: listen to sounds of blood thru arteries |
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BLOOD FLOW/VELOCITY CONTINUED...
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3. In capillary beds, need proper flow rate in each tissue area
a. deliver O2, remove waste, exchange gas with lungs, absorb nutrients from digestive tract, form urine b. blood fluids forced out arteriole end of capillary bed into INTERSTITIAL FLUID OF TISSUES c. 85% of filtered fluid forced back into capillary bed at venule end d. 15% fluid remaining in tissues is returned to great veins near heart by LYMPHATIC SYSTEM |
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PULSE PRESSURE
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= SYSTOLIC - DIASTOLIC
- difference between systolic and diastolic pr. - normal PP = 120-80 = 40 mmHg |
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REGULATION OF BLOOD PRESSURE CONTINUED...
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b. LONG TERM REGULATION OF BP
RENIN-ANGIOTENSIN-ALDOSTERONE MECHANISM -lo BP -> renin release from kidneys -> ANGIOTENSIN II -> inc. ALDOSTERONE release -> inc. Na+ retention -> inc. water retention (if ADH present)-> inc. blood volume, BP -hi BP kidneys excrete more water and Na+, dec. volume, BP |
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MEAN ARTERIAL PRESSURE
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average of hi and lo pressures
-but heart in diastole longer than in systole MAP = DIASTOLIC + PP/3 93mmHg = 80 + 40/3 |
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PULSE
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alternating expansion & recoil of artery wall due to blood surge during vent. systole
Gives info about rate, strength, and rhythmicity of heart beat 1. pulse points = pressure points: felt where AA. are near body surface over bone or muscle: temple, chin, ankle, neck, axilla, brachial region, femoral, popliteal, etc |
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STEPS FOR MEASURING BLOOD PRESSURE
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d. STEPS
1) INFLATE CUFF: when pr. in cuff is greater than pr. in artery, VESSEL OCCLUDED no blood passes 2) SLOWLY RELEASE PR. IN CUFF WHILE LISTENING TO OCCLUDED ARTERY: when pr. in cuff is less than pr. in artery during ventricular systole, blood spurts thru artery causing KOROTKOFF SOUNDS 3) NOTE PRESSURE WHEN FIRST HEAR KOROTKOFF SOUNDS: = SYSTOLIC PRESSURE 4) NOTE PRESSURE WHEN SOUNDS DISAPPEAR: pressure in artery now is always greater than cuff, blood flows smoothly = DIASTOLIC PRESSURE 5) RECORD BP: SYSTOLIC/DIASTOLIC pressure mmHg e. normal BP = 120/80 mmHg |
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NET FILTRATION PRESSURE
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HPc = Hydrostatic Pressure of blood in Capillary which pushes small materials OUT OF THE CAPILLARY into interstitial fluid
HPif = Hydrostaic Pressure of the Interstitial Fluid which pushes small materials out of the interstitial fluid INTO THE CAPILLARY OPc = Osmotic Pressure of blood in the Capillary caused by large solutes especially plasma proteins pulling fluids out of the interstitial fluid INTO THE CAPILLARY OPif = Osmotic Pressure of the interstitial fluid caused by large solutes, especially proteins, pulling fluids into the interstitial fluid OUT OF THE CAPILLARY |
