of 42 /42
MICROCIRCULATION. VENOUS BLOOD FLOW.

Physiology 1-Microcirculation

Embed Size (px)

Text of Physiology 1-Microcirculation

  • MICROCIRCULATION. VENOUS BLOOD FLOW.

  • Microcirculatory bedArterioli & pre-capillariesCapillariesArterio-venous anastomosesPost-capillaries

  • Functional state of capillaries

    bloodplasma

  • Medium capillaries parametersRadius 3-6 mLength 750 mCross section square 30 m2Square of exchange 14 000 m2 Linea velocity of blood flow 0,3 mm/seTime of erythrocyte staying in the capillary 2-3 se

  • TYPES OF CAPILLARIESCONTINUUS pores of 4-5 nm

    FENESTRAED fenestra in the endothelium of 0,1 m

    SINUSOIDAL

  • Capillary endothelium in relaxed muscle

    B. Capillary endothelium in contracted muscle

  • TRANSCAPILLARY EXCHANGE

    CVh/bl=30h/t=-6/t=4/pl=27f13h/pl=10/pl=28h/t=-6/t=48

  • Filtration-absorption mechanismNet hydrostatic pressure

    h/n=h/pl h/t=30-(-6)=36

    Net oncotic pressure/n=/pl-/t=27-4=23

  • Filtration-absorption mechanismFiltration pressuref=h/n-/n=36-23=13

    Absorption pressureh/n=10-(-6)=16/n=28-4=24ab=/n-h/n=24-16=8

  • LYMPHATIC SYSTEMDRENAGE SYSTEM excretes from extracellular fluid proteins & high molecular substances, which cant be reabsorbed into blood capillaries.

    2L of lymph are produced per day

  • Lymphatic vessel

    Muscle elements-Lymphatic capillaryvalvesLympho-angion

  • VENAE ARE BLOOD DEPOTSHEARTBIG ARTERIESSMALL VEINSCAPILLARIESLUNGSBIG VIENSSMALL ARTERIES

  • Factors enabling blood flow in veins1. Pressure difference (12mm Hg 0 mm Hg )2. Recoil force of heart & thorasic cavity3. Valves in veins4. Skeletal muscles contraction

  • VASCULAR TONE REGULATION

  • VASCULAR TONEBASILAR MIOGENIC TONE TONE, PROVIDED BY SMOOTH MUSCLES AUTOMATICITY.

    AORTHAVEINARTERIOLA

  • Factors, influencing vascular toneMyogenicVasoactive tissue methabolitesHumoral factors, circulating in bloodTonic nervous impulses

  • Local regulatory mechanismsMechanical stretching of vessel wall with bloodOxygen deficitMethabolitesBiologically active substances which act paracrineRegulating factors of endothelial cells of the vessels

  • Influence of blood pressure on the myogenic vascular tone

    Tone increaseTone decrease

  • Vasodilating methabolitesDecreased pressure of 2 Lactic acidPyruvic acidAdenosinIncreased pressure of 2

    decrease, + concentrationincrease

  • Biologically active substancesVasodilatorsKinins (bradikinins)Prostaglandines (1,2,1,1, 2, F2)Hystamine Vasoconstrictor - serotonin

  • Endothelium regulating factorsArachidonic acid methabolites (prostacyclin PGI2)Factor of vessel relaxation (NO)Factor of vessel contraction (ECF-endothelin)Free radicals

  • Humoral factors, circulating in blood

  • Hormones, causing vasoconstrictionEpinephrin, norepinephrinVasopressinRenin-angiotensin-aldosteron system

  • Epinephrin & norepinephrinEpinephrin in high concentration constricts the vessels via -adrenoreceptors-adrenoreceptors are sensitive to norepinephrine in physiological concentrations

  • Vasopressin Is released from posterior pituitary ADH causes vessels constrictionReceptors V1 & V2Employs intracellular messengers

  • Renin-angiotensinogen-aldosterone systemkidneyJGAReninangiotensinogenangiotensinIlungsangiotensin IIAdrenal cortexaldosteronevesselsSensitivity to epinephrine constriction+

  • Hormones, causing vasodilationEpinephrine in physiological concentrations via -adrenoreceptors.- adrenoreceptors are located in coronary vessels, brain & kidney vessels

  • Nervous influences

  • Sympathetic nervous systemAdrenergic fibersCholinergic fibers Epinephrine &norepinephrine-drenoreceptorsconstriction-drenoreceptorsdilationachetylcholineM-cholinoreceptors

  • Sympathetic nervous systemM-cholinoreceptors are in the vessels of skeletal muscles.

  • Parasympathetic nervous systemSalivatory glands vessels Pelvic organs vesselsPia mater vessels

    Acetylcholine

    m-cholinoreceptorsdilation

  • vasoconstrictorsNervous:Sympathetic nervous system via -adrenoreceptors (all vessels)

    Hymoral:Epinephrine, norepinephrineVasopressinRenin-angiotensin-aldosterone system

  • VasoconstrictorsLocal:SerotoninEndothelial factor of vessel constriction (endothelin)

  • vasodilatorsNervous:Sympathetic NS via -drenoreceptors;Sympathetic NS via cholinergic fibersParasympathetic fibers xon-reflex

  • Axon-reflex

    CNSMechanical, thermal or chemical skin irritationLocal vessel dilation

  • vasodilatorsHumoral:Epinephrine via -adrenoreceptors;Hystamine

    Local:MethabolitesBiologically active substances (prostaglandines, kinins)Endothelial factorsMechanical stretching of vascular wall

  • Tonic influence of sympathetic NSClaude Bernard experiment