Blood pressure

BLOOD PRESSUREBLOOD PRESSURE

It is the lateral pressure exerted by blood It is the lateral pressure exerted by blood on the wall of the blood vessel during its on the wall of the blood vessel during its flow.flow.

SBP,DBP,PP,MBP.SBP,DBP,PP,MBP. Measurement-Types of instruments-1.Dial Measurement-Types of instruments-1.Dial

manometer.2.Mercury manometer.2.Mercury manometer.3.Electronic manometer.manometer.3.Electronic manometer.

Methods- Palpatory, Auscultatory, Methods- Palpatory, Auscultatory, Oscillatory.Oscillatory.

Systolic pr-120mm Hg(110-140)mm HgSystolic pr-120mm Hg(110-140)mm Hg

Diastolic pr-80mmHg(60-80)mmHgDiastolic pr-80mmHg(60-80)mmHg

Pulse Pr=40mmHgPulse Pr=40mmHg

Mean Arterial Pr=93mmHgMean Arterial Pr=93mmHg

Lateral PrLateral Pr

Total Pr (Perfusion - Pr)Total Pr (Perfusion - Pr)

Normal value AdultNormal value Adult

PressurePressureVelocity- pressure relation-figVelocity- pressure relation-fig

Definition of pressureDefinition of pressure

Total pressure studyTotal pressure study

Lateral pressure study figLateral pressure study fig

Bernoulli, principleBernoulli, principle

(Total pr/Perfusion pr) E=LP+pV2/2(Total pr/Perfusion pr) E=LP+pV2/2

LP=Lateral prLP=Lateral pr

P=rho=density of bloodP=rho=density of blood

V=velocity of BFV=velocity of BF

PHYSIOLOGICAL VARIATIONPHYSIOLOGICAL VARIATION AGE – Increases with age.AGE – Increases with age. SEX – Less in female before menopause. Progesterone SEX – Less in female before menopause. Progesterone

relaxes vascular smooth muscle, Estrogen prevents relaxes vascular smooth muscle, Estrogen prevents atherosclerosis.atherosclerosis.

Body built-obeseBody built-obese Diurnal -Diurnal - DIET – Increases after food intake.DIET – Increases after food intake. SLEEP - DecreasesSLEEP - Decreases POSTURE – Standing decreases.POSTURE – Standing decreases. TEMPERATURE – Hot decreases, Cold IncreasesTEMPERATURE – Hot decreases, Cold Increases PREGNANCY-Pulse pressure increases.PREGNANCY-Pulse pressure increases. ExerciseExercise Fear,anxiety,Fear,anxiety, EmotionEmotion Mental StressMental Stress

Age variationAge variation

Age Systolic mmHg Diastolic mmHg

New born 40 ---

1month-1 year 90 ---

Puberty 120 80

>50 years 140 85

>70Years 150 85

>80years 160 90

EXERCISE & BLOOD EXERCISE & BLOOD PRESSUREPRESSURE

Effect of exerciseEffect of exercise

Variant Effect Cause

Heart rate Chrono/Iono/bath/dromo

Symp.Stim/releaseof catecholamines/decrease vagal tone/Increase Temp

Cardiac output Normal-5l/mt increase to25l/mt

Increase cotractility/VREnhanced

Coronary Blood flow Normal-@250ml/mt increase to1L/mt

Beta recepter mediated coronary V.DilatatiHypoxia/Hypercapnia /acidosis

BP-SystolicBP-Diastolic

IncreaseDecrease

Increase of CODecrease PR

Pulse Pressure Increase More gap in SBP/DBP

DIRECT METHODDIRECT METHOD

INDIRECT METHODINDIRECT METHOD

KOROTKOFF SOUNDSKOROTKOFF SOUNDS

PHASE I – FAINT TAP GRADUALLY PHASE I – FAINT TAP GRADUALLY CLEAR AND LOUDER.CLEAR AND LOUDER.

PHASE II – MURMURISH.PHASE II – MURMURISH. PHASE III – CLEAR AND LOUDER.PHASE III – CLEAR AND LOUDER. PHASE IV – MUFFLINGPHASE IV – MUFFLING PHASE V – DISAPPEARANCE. PHASE V – DISAPPEARANCE.

FACTORS AFFECTING BPFACTORS AFFECTING BP

Blood pressure = C.O X PR So all factors which Blood pressure = C.O X PR So all factors which affect this 2 things affect BP.affect this 2 things affect BP.

C.O –Preload, After load, Heart rate, Myocardial C.O –Preload, After load, Heart rate, Myocardial contractility. contractility.

Peripheral resistance – Diameter of blood Peripheral resistance – Diameter of blood vessel, Viscosity. Vasoconstriction increases PR vessel, Viscosity. Vasoconstriction increases PR & Vasodilatation decreases it.& Vasodilatation decreases it.

Viscosity increases- Polycythaemia, Viscosity increases- Polycythaemia, Hyperprotinaemia, H-Altitude, Decrease temp.Hyperprotinaemia, H-Altitude, Decrease temp.

Viscosity decreases-Anemia, Hypoprotinaemia, Viscosity decreases-Anemia, Hypoprotinaemia, Increase temp.Increase temp.

Determinant of Blood pressureDeterminant of Blood pressure

Central factorsCentral factors--

CO &HRCO &HR

Peripheral factors-Peripheral factors-

1.Periferal resistance1.Periferal resistance

2.Blood volume2.Blood volume

3.Venous return3.Venous return

4.Elastisity of BV4.Elastisity of BV

5.Velocity of flow5.Velocity of flow

6.Diameter of BV6.Diameter of BV

7.Viscosity7.Viscosity

Determinant of Blood PressureDeterminant of Blood Pressure

ResistanceResistance Ohm’slaw=Relation of current/pot diff/resistance=Ohm’slaw=Relation of current/pot diff/resistance=I=pd/rI=pd/rModified Ohms lawModified Ohms lawQ=P/RQ=P/RQ=(P1-P2)/RQ=(P1-P2)/RQ=FlowQ=FlowP=Pressure gradientP=Pressure gradientR=ResistanceR=ResistanceR=(P1-P2)/QR=(P1-P2)/Q Hagen- poiseuille’s law Hagen- poiseuille’s law

Q= Q= (P1-P2)X(P1-P2)Xππr4r4 88ηηll

= ( P1-P2)/ = ( P1-P2)/ (P1-P2)x(P1-P2)x π πr4 r4 = R=8= R=8ηηl/l/ππr4r4 88ηηl l

Medullary cardiovascular control Medullary cardiovascular control centercenter

Concept of Vasomotor ToneConcept of Vasomotor Tone

Innervation of BV—Sympathetic Innervation of BV—Sympathetic dominancedominance

Due to cont.discharge from ILHC of Due to cont.discharge from ILHC of SP.CordSP.Cord

Concept of Vagal ToneConcept of Vagal Tone

Innervation of Heart—Parasympa-Innervation of Heart—Parasympa-dominancedominance

Right VagusRight Vagus

Left VagusLeft Vagus

Method of studyMethod of study----

Dominance of Autonomic toneDominance of Autonomic tone

Innervations of BV-Innervations of BV-

Sympath-Vasoconstrictor fibre-Vaso motor Sympath-Vasoconstrictor fibre-Vaso motor tone.Method of studytone.Method of study

Para sympath Vasodilator fibrePara sympath Vasodilator fibre

Anatomically symp -functionally ParaAnatomically symp -functionally Para

Method of studyMethod of study

Cardiac innervationsCardiac innervations

Symp-T1-T5 ofSymp-T1-T5 of

Parasymp-Vagus (Rt & Lt)Parasymp-Vagus (Rt & Lt)

Method of studyMethod of study

InnervavationInnervavation

Baroreceptor reflexBaroreceptor reflex

REGULATORY MECHANISMSREGULATORY MECHANISMS

REGULATIONREGULATION

These mechanisms try to maintain These mechanisms try to maintain mean B.P within 95-100mmHg.mean B.P within 95-100mmHg.

1.Rapidly acting.1.Rapidly acting. 2.Intermediate.2.Intermediate. 3.Long term.3.Long term. 4.Miscellaneous.4.Miscellaneous.

SHORT TERMSHORT TERM Act within seconds to minutes.Act within seconds to minutes. Control major immediate changes. Control major immediate changes.

Change in posture, Acute blood loss.Change in posture, Acute blood loss. Loss their capacity within days.Loss their capacity within days. Various reflexes.Various reflexes. 1.Baroreceptor reflex.-60-200mmHg.1.Baroreceptor reflex.-60-200mmHg. 2.Chemoreceptor reflex.40-2.Chemoreceptor reflex.40-

100mmHg.100mmHg. 3.CNS Ischemic response.15-3.CNS Ischemic response.15-

50mmHg.50mmHg. 4.Respiratory reflex-Inspi/Expi4.Respiratory reflex-Inspi/Expi

CNS ISCHAEMIC RESPONSECNS ISCHAEMIC RESPONSE

Fall in B.P-20-30mmHg-Decrease Fall in B.P-20-30mmHg-Decrease perfusion to brain-CNS Ischaemia-CO2 perfusion to brain-CNS Ischaemia-CO2 accumulation in VMC-Direct accumulation in VMC-Direct stimulation of VMC (Pressure area)-stimulation of VMC (Pressure area)-Powerful sympathetic discharge all Powerful sympathetic discharge all over body-HR,B.P increase to maintain over body-HR,B.P increase to maintain normal blood supply to brain.normal blood supply to brain.

This mechanism is the final frontier to This mechanism is the final frontier to prevent the death of the person.prevent the death of the person.

BARO & CHEMORECEPTORSBARO & CHEMORECEPTORS

Arterial baroreceptorsArterial baroreceptors

Direct stimulationDirect stimulation Hypoxia, HypercapniaHypoxia, Hypercapnia

Stimulatory inputStimulatory inputFrom Cortex via hypothalamusFrom Cortex via hypothalamus

From pain pathway, Joint, Muscle(Somato Sympathetic reflex) linkFrom pain pathway, Joint, Muscle(Somato Sympathetic reflex) link

From carotid, aortic chemoreceptorFrom carotid, aortic chemoreceptor

Inhibitory inputInhibitory inputFrom cortex via hypothalamusFrom cortex via hypothalamus

From lungFrom lung

From BarorecepterFrom Barorecepter

Factors affecting VMCFactors affecting VMC

MEDULLARY CENTERSMEDULLARY CENTERS

BARORECEPTOR REFLEXBARORECEPTOR REFLEX

CHEMORECEPTOR CHEMORECEPTOR CONTROLCONTROL

LONG TERM REGULATIONLONG TERM REGULATION

R.A SYSTEM-(Long term)R.A SYSTEM-(Long term)

1.Epinephrine/Nor epinephrine1.Epinephrine/Nor epinephrine

2.Thyroxin2.Thyroxin

3.Aldosterone3.Aldosterone

4. Vasopressin4. Vasopressin

5. Serotonin/Bradykinin/histamine5. Serotonin/Bradykinin/histamine

6.VIP6.VIP

7.Prostaglandine7.Prostaglandine

8.Acetyl choline8.Acetyl choline

9.ANP9.ANP

Hormonal regulationHormonal regulation

Chemical Physiologic role Source Type

Nitric oxide Paracrine mediator Endothelium Local

Atrial natriuretic peptide

Reduce blood pressure Atrial myocardium, brain

Hormonal

Vasoactive intestinal peptide

Digestive secretion, relax smooth muscle

Neurons Neural, hormonal

Histamine Increase blood flow Mast cells Local, systemic

Epinephrine (2) Enhance local blood flow to skeletal muscle, heart, liver

Adrenal medulla Hormonal

Acetylcholine (muscarinic)

Erection of clitoris, penis Parasympathetic neurons

neural

Bradykinin Increase blood flow via nitric oxide

Multiple tissues Local

Adenosine Enhance blood flow to match metabolism

Hypoxic cells local

Substances that mediate vascular smooth muscle relaxation

Chemical Physiologic role Source Type

NE ( ) Baroreceptor reflex Sympathetic neurons Neural

Endothelin Paracrine Vascular endothelium Local

Serotonin Platelet aggregation, smooth muscle contraction

Neurons, digestive tract, platelets

Local, neural

Substance P Pain, increased capillary permeability

Neurons, digestive tract

Local, neural

Vasopressin Increase blood pressure during hemorrhage

Posterior pituitary Hormonal

Angiotensin II Increase blood pressure Plasma hormone Hormonal

Prostacyclin Minimize blood loss from damaged vessels before coagulation

endothelium local

Substances causing contraction in vascular smooth muscle

Local RegulationLocal Regulation

Local Vasoconstrictors Local Vasodilators

Endothelial originET1,ET2,ET3

MetabolicOrigin

Endothelialorigin

Co2/LactateH+adenosine

NO

If BP Fall< 60mmHgIf BP Fall< 60mmHg

CNS-devoid of o2CNS-devoid of o2

VMC- StimulatedVMC- Stimulated

Vasocnstriction occurVasocnstriction occur

BP stabilised to save lifeBP stabilised to save life

Cushing Reflex-Cushing Reflex-

CNS Ischemic ResponseCNS Ischemic Response

MISCELLANEOUSMISCELLANEOUS 1.Role of sympathetic nerves-Sympathetic nerves 1.Role of sympathetic nerves-Sympathetic nerves

of kidney are stimulated for several weeks-Renal of kidney are stimulated for several weeks-Renal retention of fluid-Chronic rise of B.P. Probable retention of fluid-Chronic rise of B.P. Probable cause of essential hypertension-Increase cause of essential hypertension-Increase sensitivity of kidneys to sympathetic discharge.sensitivity of kidneys to sympathetic discharge.

2.Role of ADH-Direct effect-Large doses-Increase 2.Role of ADH-Direct effect-Large doses-Increase vasoconstriction-Increase B.P.vasoconstriction-Increase B.P.

Indirect effect-Fall in B.P-Decrease atriocaval Indirect effect-Fall in B.P-Decrease atriocaval discharge.- Increase ADH secretion –Fluid discharge.- Increase ADH secretion –Fluid retention-Rise in B.P-(Reverse)retention-Rise in B.P-(Reverse)

So it has both Short term and long term effects.So it has both Short term and long term effects. Corrects 75% fall in B.P in minutes-Corrects 75% fall in B.P in minutes-

VASOCONSTRICTION.VASOCONSTRICTION. Also has long term effect through kidney. Also has long term effect through kidney.

APPLIEDAPPLIED

HYPERTENSION- HYPERTENSION- 1. ESSENTIAL1. ESSENTIAL

2.SECONDARY (Polycythaemia, O.C Pill, 2.SECONDARY (Polycythaemia, O.C Pill, Cons syndrome, Kidney disease, Cons syndrome, Kidney disease, Endocrine, Thyrotoxicosis.)Endocrine, Thyrotoxicosis.)

HYPOTENSION.HYPOTENSION.