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2012-05-06 15:02:52
circulatory system blood vessels circulation

circulatory system blood vessels and circulation
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  1. describe the structure and fxn of arteries:
    • structure: 3 layer tunics,
    • tunica interna- simple squamous epithelium, basement membrane, loose connective tissue
    • tunica media- thick, smooth muscle, collagen, elastic tissue
    • tunica externa - outermost layer, loose connective tissue, anchors vessel and passage for small nerves

    fxn: efferent vessels that carry blood away from the heart
  2. describe the structure and fxn of the arterioles:
    • structure: considerable amount of smooth muscle, little elastic tissue
    • fxn: important for blood flow
  3. describe the structure and fxn of capillaries:
    structure: 1 cell thick, basement membrane, no muscle, no connective tissue, very small diameter (7-10 microns), RBC must squezze thru, >1 billion capillaries, 25000 miles, most cells only 4-6 cell widths away from capillaries

    fxn: gas, water, nutrient/ wastes exchange, short diffusion distance
  4. describe the structure and fxn of conducting (large) arteries:
    • structure: considerable elastic tissue
    • fxn: withstands high BP, expand during ventricular systole to receive blood and recoil during diastole
    • examples: aorta, common carotid, and subclavian arteries
  5. describe the structure and fxn of distributing ( medium) arteries:
    • structure: smooth muscle and less elastic tissue
    • fxn: distribute blood to specific organs
    • example: brachial a., femora a., and splenic a.
  6. describe the fxn of the carotid sinuses:
    • baroreceptors (pressure sensors) that respond to changes in blood pressure
    • increase in stretch, increases firing
    • crainal nerve IX, glossopharyngeal transmits the signals
  7. describe the fxn of the carotid bodies:
    chemoreceptors that monitor changes in blood composition, transmits signals about blood pH, CO2, and O2.
  8. describe the fxn of the aortic bodies:
    chemoreceptors that detect changes in pH, CO2, and O2 (same fxn as carotid bodies)
  9. describe the fxn of capillary beds:
    • arterioles led into metarterioles
    • metarterioles connects artery with capillary bed, 10- 10 metarterioles supplied by metaterioles
    • sphincters - when open capillaries have blood and engage in exchanges, when closed blood bypasses the capillaries, 3/4 of the bodies capillaies are shut down at any given time
  10. describe the structure and fxn of veins:
    • structure: capacitance vessels b/c they are relatively thin walled and flaccid, and expand easily to accommodate an increased volume of blood. low pressure - 10 mm Hg
    • fxn: afferent vessels that carry blood back to the heart
  11. describe the structure and fxn of the venules:
    • structure: no muscle
    • fxn: exchange fluid with surrounding tissues
  12. describe the fxn of the medium veins:
    • valves-muscle (pump)
    • keeps blood flowing in one direction
  13. describe the structure and examples of the large veins:
    • structure: smooth muscle
    • venae cavae, pulmonary veins, internal jugular veins, and renal veins
  14. describe the variations in circulatory pathways:
    • a. simplest pathway: 1 capillary bed
    • b. portal system: 2 capillary beds, liver, kidneys, anterior pituitary
    • c. ateriovenous anastomosis: shunt, blood flows directly from an artery to a vein, fingers, toes, ears (decreased heat loss)
    • d. venous anastomoses: one vein empties directly into another, most organs
    • e. arterial anastomoses: two arteries merge, heart
  15. define anastomosis:
    the point where two vessels merge
  16. define portal system:
    blood flows thru two consecutive capillary networks before returning to the heart
  17. understand the purpose and trace the pathway of circulation thru the pulmonary system:
    • purpose: exchange O2 and CO2, slow capillary flow, for efficient gas exchange
    • pathway: pulmonary trunk ascends from right ventricle > branches into pulmonary arteries (low on O2!!) > capillary beds > pulmonary veins (red, O2 rich) > left atrium
  18. understand the purpose and trace the pathway of circulation of the hepatic portal system:
    • purpose: distribute nutrients to the liver and the rest of the body, cleanse the blood of bacteria/toxins
    • pathway: inferior mesenteric vein ( recvs blood from colon) > superior mesenteric vein > (recvs blood from small intestine) > splenic vein > hepatic portal vein (empty into the IVC) > gastic vein (empty into the hepatic portal vein)
  19. define hemodynamics and explain the factors that regulate blood flow:
    • hemodynamics: the physcial principles of blood flow, based mainly on pressure and resistance
    • factors that regulate: blood pressure, vessel radius, hematocrit, blood albumin concentration, distance from the heart
  20. The carotid bodies sense changes in _______, while the ______ detect(s) changes in blood pressure.

    blood pH and O2 levels; carotid sinus
    blood chemistry; chemoreceptors
    respiration rate; aortic bodies
    heart rate; baroreceptors
    blood pH and O2 levels; carotid sinus
  21. A/an _________ is a point where two blood vessels merge. (0.25pts)

    capillary plexus
    portal system
  22. ________ pressure is the blood pressure attained during ________ contraction, whereas ________ pressure occurs during ventricular ________. (0.5pts)

    systolic; ventricular; diastolic; relaxation
    diastolic; arterial; systolic; contraction
    systolic; arterial; diastolic; contraction
    hydrostatic; ventricular; systolic; relaxation
    diastolic; ventricular; systolic; relaxation
    systolic; ventricular; diastolic; relaxation
  23. After following the Rib-wich tour around the nation, Homer gained 50 lbs. Now his blood pressure is consistently 146/93. Which of the following conditions does Homer have? (0.25pts)

  24. Which of the following is NOT a factor influencing hemodynamics? (0.5pts)

    blood pressure
    vessel radius
    blood albumin concentration
    distance from the heart
  25. Which of the following factors reduces blood pressure? (0.5pts)

    blood O2 deficiency
    antidiuretic hormone (ADH)
    A&P exams
  26. Which of the following aid venous return ? Choose ALL that apply. (0.5pts)

    osmolarity gradient
    cardiac suction
    smooth muscle contraction
    • cardiac suction
    • gravity
  27. Which of the following causes accumulation of excess fluid in tissue? Choose ALL that apply. (0.5pts)

    decreased blood albumin concentration
    increased capillary filtration
    reduced capillary reabsorption
    obstructed lymphatic drainage
    all choices above
  28. Through which of the following does blood flow the slowest? (0.25pts)

    extensor digiti minimi
  29. describe how blood pressure is measured and know normal values:
    • 1. no sound, cuff pressure about systolic pressure; artery completely occluded during cycle
    • 2. cuff pressure just below systolic pressure; first sounds heard, soft, tapping, and intermittent
    • 3. sounds loud, tapping, and intermittent
    • 4. low muffled, sound lasting continulously
    • 5. cuff pressure below diasolic pressure, thus vessel is always open, no turblence, no sound

    normal value: age 20 - 30 is 120/75
  30. define and be able to calculate pulse pressure:
    • define: the maximum stress exerted on small arteries by the pressure surges generated by the heart
    • calculate: systolic pressure - diastolic pressure
  31. define and be able to calculate mean arterial pressure:
    • define: average pressure for the whole body
    • calculate: diastole lasts longer than systole, so diastolic pressure - pulse pressure/3
  32. define and discuss the causes and effects of hypertension:
    • define: chronic resting blood pressure higher than 140/90
    • causes: retention of Na+/water, obesity, nicotine
    • effects: weaken small arteries, promote atierosclerosis, lead to heart/renal failure
  33. define and discuss the causes and effects of hypotension:
    • define: chronic low resting blood press
    • causes: blood loss, dehydration, anemia
    • effects:
  34. define and discuss the causes and effects of arteriosclerosis:
    • define: hardening of the arteries, loss of elasticity
    • causes: cumulative damage by free radicals
    • effects: blood pressure rises
  35. define and discuss the causes and effects of atherosclerosis:
    • define: growth of lipid deposits in the arterial walls
    • causes: build up of cholesterol, lipoproteins, and cell debris
    • effects: blood pressure rises
  36. discuss pressure changes within the cardiovascular system:
    • Systolic pressure, pulse elasticity (120 mmHg), so High pressure
    • with increasing distance from left venticle - diastolic pressure, and then the veins - low pressure
  37. disucss factors that affect peripheral resistance:
    • the oppostion of flow that blood encounters in vessesl away from the heart
    • viscosity: erythrocyte count/albumin concetentration, a deficiency reduces viscosity, and speeds up blood flow
    • vessel length: increased distance, so inceased friction, increased resistance, so decrease blood flow
    • vessel radius: resistance from moment to moment is controlled by vasomotion -
    • a. vasoconstriction - narrowing of a vessel, increase BP
    • b. vasodilation - widening of a vessel, decreased BP
  38. define laminar flow:
    • blood flows faster near the center of the vessel, where it encounters less friction, and slower near the walls, where it drags against the vessel
    • flow increases 16x with only a 2x increase in radius
  39. explain how and why the body redirects blood flow:
    • how: example, during exercise, SN can reduce flow to the kidneys and digestive tract (vasoconstiction), increase flow to the skeletal mucles (vasodilation), or while sitting increase flow to the intestines (vasodilation), and decrease flow to skeletal muscles (vasoconstriction)
    • why: to meet the changing metabolic priorities of the body
  40. descirbe the parallel flow:
    same blood qlualtity to all tissues
  41. describe the systemic blood flwo during rest and activity:
    • at rest
    • total cardiac output 5L/min
    • cerebral gets 700 ml/min (14%)

    • during exersice
    • total cardiac output is 17.5 L/min
    • cerebral gets 750 ml/min (4.3%)

    summary: muscles, skin, digestive, and renal may get more or less flow, but the brain always gets the same
  42. explain the importance of capillary exchange:
    • uses ATP + H2o > CO2 < O2 + glucose (gives off CO2 waste)
    • decreased velocity: smaller tones, friction/distance, capillary radius, allows time for exchange
    • increased velocity: increased cross -section area (blood spread out), vessle gets bigger, speed not P
  43. explain the mechanism of capillary exchange:
    • lipid - solule substances pass thru the ednotheila cells > O2, CO2, steroids * diffusion thru the membrane
    • small water soluble substances pass thru the pores *filtration + reabsorption (Na+, K+, amino acids)
    • exchane proteins are moved across by vesicular transport - transcytosis (insulin)
    • plasma proteins: inside the membrane, cannot cross the capillary wall
  44. describe the forces of filtration and absorbtion in capillary exchagne:
    2 pressures: hydrostatic (HP) and Colloid osmotic (COP)

    • start
    • high BP: HP is greater than COP, so filtration
    • HP pushes fluid out, COP tries to resist (arterial end)

    • end
    • lower BP: HP is less than COP, so reabsorption
    • fluid in
    • venous end

    • *COP does change
    • increase fluids when ill, increase HP- more fluid cleared via lymphatics
    • 85% reabsorbed
    • 15% lymphatics
  45. define and describe what causes edema:
    • accumuation of excess fluid in tissues
    • caused by hypertension, heart failure (lower venous return)
    • injury > histamine released > vasodiliation
    • capillaires: increased filtration, decreased reabsorption
    • plasma protein/albumin deficiency (hypoprotein-emia) > reduces reabsorption
    • kwashiorkor: thin limbs, swollen abdomen
    • lymphatic obstruction: elephantitis, round worms infect lymph nodes + block lymph flow
  46. state mechanisms that aid in venous return:
    blood flow back to the heart: pulmonary or systemic

    • assistance
    • skeletal muscle pump: contraction
    • respiratory pump: inhaling creates negative pressure, IVC has positive pressure
    • SNS: constriction
    • valves: prevent back flow b/w contractions

    increased venous return: increased EDV, increase stroke volume
  47. explain what varicose veins are and what causes them:
    • weakness of valves, blood pools
    • vesseles streach, veins weaken
  48. describe the factors that determine blood pressure:
    • total peripheral resitances (TRP): vasomotion
    • CO= HR x SV
    • MABP= CO x TRP
    • arterioles affect TPR the most: 1. mostly muscluar vessels as compared to other vessels 2. control flow to capillary beds
  49. explain how the SNS controls blood pressure:
    • alertness, "flight or fight"
    • increased, HR, Increased BP, increased blood flow to heart/skeletal muscles (vasodiliation)
    • decrease blood flow to GI tract/vasoconstriction
    • increase contractility (force of contraction)

    • PSNS
    • calming effect
    • decrease HR, no blood vessle impact in skeletal muscles
    • increased digestion/waste elimination
    • reduced contractility (force of contraction)
  50. explain the local control of blood pressure:
    • autoregulation
    • vasodiliation
    • caused by decreased O2, increased waste (CO2, H+, and lataic acid) in tissues
    • paracrine agents: histamine, prostaglandins released > vasodilation
  51. describe the neural control of blood pressure:
    • more generalized (systemic) effect
    • vasomotor center of meduall

    • SNS
    • increased HR, increased venous return
    • vasoconstriction,except skeletal muscles + cardiac muscles: vasodiliation
    • w/o SNS: vasodiliation, no dual innervation with PSNS

    • baroreflex
    • increased BP, increased baroreceptor firing
    • increased PSNS + inhibits SNS: vasodiliation, increased radius > decreased resistance (decreased TPR) > decreased BP
    • short term BP reuglation: standing vs. lying + adjustments
    • not good for long term (ex. hypertension)

    low BP (dehydration, bleeding) > decreased BP > decreased stretch > decreased baroreceptor firing > decrease PSNS + increase SNS > vasoconstriction > decrease radius > increased resistance TPR > increase BP

    • chemoreflex
    • pulmonary system
    • decreased O2, increased CO2, increased H+ (acidosis) > vasoconstriction
    • decreased radius> increased resistance (TPR) > increase BP
    • increase blood flow to the lungs, increase lung perfusion
    • stimulates breathing
  52. describe the hormonal control of blood pressure
    long term control due to changes in blood volume

    • increased BP
    • angiotensin II: releases aldosterone- potenet vasoconstrictor, causes Na+ retention (increase BV, increase BP)
    • ADH: causes water rention (increase BV, increase BP), vasocostriction
    • epienphrine/NE: same effects as SNS

    • decreased BP
    • artrial naturetic peptide (ANP): vasodiliation, opposes aldosterone, increase Na+/water excretion (decreased BV + BP)
    • blood test available, heart failure correlation