Biophysics of Heart and Circulation. Heart as a source of biopotentials. Heart as a pump. Blood flow in vessels.

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Biophysics of Heart and Circulation. Heart as a
source of biopotentials. Heart as a pump. Blood
flow in vessels.

• Ján Jakuš

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Anatomy of Heart

• - consists of 4 chambers from 2 Atrias (A) and
  2 ven-tricles (V)
• - wall of Left Ventricle (LV ) is 3 x thicker
  than a wall of the Right Ventricle (RV)
• - between RA and RV there is a tricuspid valve
  , bet-ween LA and LV is a bicuspid valve.
• - within the pulmonary artery, at a place where
  it leaves the heart, there is the pulmonary
  valve.
• - similarly, within the aorta there is the
  aortal valve
• - two coronary arteries bring the nutritiens
  and O2 for heart
• - Conductive system (nerve tissue within the
  heart) Sinoatrial node (SA), Atrio-ventricular
  node (AV ), Hiss bundle, Two branches of Tawara,
  Purkynie fibers.

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Heart - structures
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Heart Source of Electric Biopotentials
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Action Potential of Sinoatrial Node and
Prepotential
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Spreading of Electric Depolarisation in the Heart

• ECG (see practicals) is a record of heart
  biopotentials
• from the body surface. Waves P,T,U, Oscilations
  
• Q,R,S,Segments PQ,ST,QT, Intervals PQ,ST,QT

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Heart as a Pump
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Heart 2 coupled pumps
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Dynamics of Heart

• Heart - 2 pumps, working together at the same
  time
• Systola - ejection of blood from ventricles-
  H.contraction
• Diastola - filling in ventricles with blood - H.
  relaxation
• Volume of blood from RV Volume of blood from LV
• Systolic volume (SV) 70 ml ( volume of blood
  ejected from each ventricle during heart
  contraction)
• Diastolic volume of a ventricle (DV) 130 ml
  (blood
• volume retained at ventricles during diastole
• Cardiac Output / min CO SV x Heart rate/
  min.
• 
  CO 70 x 72 5 (l/min.)
• Work of heart/60 years of life move 60.000 kg
  of
• matter to the altitude of 8.000 m
• Work of LV 0,94 J/systole, Work of RV 0,19 J/
  systole

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DIASTOLE - filling SYSTOLE - ejection
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Blood Pressures in Heart

• Right Atrium (systole/diastole) 0,6 /-0,6
  (kPa)
• Right Ventricle 4,6
  / 0 !
• Pulmonary Artery 4,6 /
  1,2
• Left Atrium
  0,6 /-0,6
• Left ventricle
  16 / 0 !
• Aorta
  16 / 10
• At diastole, there are zero pressures within the
  ventricles !
• At diastole, there are positive values of blood
  pressures both
• in the aorta and pulmonary artery, because
  ELASTICITY of
• the vessels (See practical A model of elasticity)

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Elasticity of aorta and arteries

• During ventricular systole - blood distends an
  aorta
• (kinetic energy -E- of a blood flow changes
• into potential E)-we can take Syst.BP
• Ventricular diastole- diameter of
• vessels decreases (potential Energy
• changes into kinetic one)- diastolic
• BP is measured
• Elasticity of vessels enables
• 1.Blood flow during diastole,
• 2.Diastolic BP,
• 3 Lower Work of heart

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BLOOD CIRCULATION

• A./ Big blood circuit - between LV and RA (there
  is a
• high BP and Pressure gradient PG 100 mm Hg
  (15kPa)
• Short blood circuit (lung circuit)-between RV and
  LA,
• PG 30 mmHg (4 kPa)
• Portal blood circuit (btw. Hepatic artery and
  Portal vein)
• Fetal blood circuit in foetus
• B./Distributive circuit (highly pressurized
  aorta, arteries)
• Resistive circuit(arteriolies-contain smooth
  muscles in wall
• Diffusive circuit (capillaries-they create
  capillary loops)
• Capacitive circuit (veins and lymphatic vessels)
• Blood flows only along Presuure gradient !
  
• Highest flow - in aorta- 30 cm/s, Lowest
  flow - in cap-
• illaries - 1mm/s

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Blood flow

• Blood flow F ( l.s-1 )Pressure of blood/
  Resistance of vessel,
• F ( l.s-1 P/ R
• Blood flow depends linearly on Pressure
  Gradient, and non-linearly on an arteriolar
  resistance as well as on the composition of a
  blood (and thus on a blood viscosity)
• Blood viscosity (is 4,5 x higher (4,5 mPa/s) then
  viscosity of distilled water. (e.g. when
  viscosity increases a blood flow decreases and
  vice versa.
• Poiseuille-Hagen Law
• Q p . r4 . (P1-P2) (Q- amount of blood, r -
  vessel radius
• 8 . ? . L ? - blood
  viscosity, L- lenght of vessel,
• p- Ludolph
  number,P1,P2- B.Pressures)

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Bernoulis Law When blood flows through the
narrow vessel the velocity of flow is higher but
pressure of blood within is lower (and vice-versa)
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TYPES OF BLOOD FLOWLaminar flow
parabolical shape of a streamline with max.
velocity in the middle of the stream and the
lowest velocity at the edges. Turbulent flow-
velocity is very high, it creats
soundRaynoldsove císlo
R ?.d.v it informs if flow is
laminar (when R lt, 1100) ? or
turbulent ( when R gt 1100)
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Types of Blood Pressures(curve is taken from a
direct measurement of BP)
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Measurement of BP (non-direct method)

• Riva Roccis auscultatory method,Korotkov
  Sounds, Systolic and diastolic BP are taken
  (See practical for theory and procedure)

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Filtration at Capillary Loop

• Capillary a place for filtration of water
  and nutritiens and a resorption of metabolic
  wastes , and for O2 a CO2 diffusion.

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Capillary Filtration and Resorption - animation
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Failures of Cappilary Filtration and Resorption

• When the capillary transfer is damaged the OEDEMA
  (tissue
• swelling) appears. It is an accumulation of
  fluid among cells
  
• Causes
• 1. Increase of Systemic Blood Pressure
  (hypertension),
• 2. Decrease of an Oncotic Presure- less than -
  25 mmHg (a
• suction effect is lower and water retains within
  the tissue,
• that swells- as it appears in a disease
  Kwashiorkor, which is
• kind of protein deficiency) ( with typical big
  bellies in
• childrens) at economical poor countries
• 3. Increase in Capillary Permeability (something
  is wrong with
• the capillary wall- as seen in the Vibration
  disease or follo-
• wing some toxic effect of animal poisons on
  vessel permea-
• bility, e.g. snakes or scorpions )
• 4. Disorders affecting the Lymphatic System ( the
  lymphatic
• circulation stops, because either cancer or
  parasite blocks
• the lymphatic vessels

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Atherosclerosis of Heart Coronary Vessels
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TREATMENTAngioplasty. Non-Surgical (Stenting)
or Surgical (By-passing)

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Stenting and By- passing
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Thank You for Comming and Attention