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CARDIOVASCULAR PHYSIOLOGY. Dr. Poland Room 3-007, Sanger Hall Phone: 828-9557 E-mail: [email protected] HEART (PUMP). AUTOREGULATION. CARDIOVASCULAR SYSTEM. NEURAL. REGULATION. HORMONAL. VESSELS (DISTRIBUTION SYSTEM). RENAL-BODY FLUID CONTROL SYSTEM. PULMONARY CIRCULATION.

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Cardiovascular physiology

CARDIOVASCULAR PHYSIOLOGY

Dr. Poland

Room 3-007, Sanger Hall

Phone: 828-9557

E-mail: [email protected]


HEART

(PUMP)

AUTOREGULATION

CARDIOVASCULAR SYSTEM

NEURAL

REGULATION

HORMONAL

VESSELS

(DISTRIBUTION SYSTEM)

RENAL-BODY FLUID

CONTROL SYSTEM


PULMONARY

CIRCULATION

1. LOW RESISTANCE

2. LOW PRESSURE

(25/10 mmHg)

SYSTEMIC

CIRCULATION

1. HIGH RESISTANCE

2. HIGH PRESSURE

(120/80 mmHg)

PARALLEL

SUBCIRCUITS

UNIDIRECTIONAL

FLOW


ARTERIES (LOW COMPLIANCE)

HEART

DIASTOLE

VEINS

CAPACITY

VESSELS

80 mmHg

120 mmHg

SYSTOLE

CAPILLARIES


THE SYSTEMIC CIRCULATION

CAPACITY VESSELS



AUTOMATICITY

Na+

K+

Gradually

increasing PNa

K+

Na+

-0

-70 mV

THRESHOLD

RESTING


Atrio-ventricular (AV) node

Sino-atrial

(SA) node

BUNDLE

BRANCHES

PURKINJE FIBERS



Pacemakers in order of their inherent rhythm
PACEMAKERS (in order of their inherent rhythm)

  • Sino-atrial (SA) node

  • Atrio-ventricular (AV) node

  • Bundle of His

  • Bundle branches

  • Purkinje fibers


PHASE

Mechanical Response

0 = Rapid Depolarization

(inward Na+ current)

1

1 = Overshoot

2

0

2 = Plateau

(inward Ca++ current)

3 = Repolarization

(outward K+ current)

0

MEMBRANE POTENTIAL (mV)

4 = Resting Potential

3

4

-90

TIME


ACTION POTENTIALS

VENTRICULULAR

CELL

SAN

1

2

0

0

0

3

0

3

4

-50

-50

MEMBRANE POTENTIAL (mV)

4

-100

-100


SINGLE VENTRICULAR ACTION POTENTIAL

ENDOCARDIAL FIBER

ATRIAL

FIBER

EPICARDIAL FIBER

R

1 mV

ECG

T

P

Repolarization of ventricles

Q S

Depolarization of ventricles

Depolarization of atria


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

LL


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

II = RA vs. LL (+)

LL


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

LL


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

3 Augmented Limb Leads:

LL

aVR = (LA-LL) vs. RA(+)


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

3 Augmented Limb Leads:

LL

aVR = (LA-LL) vs. RA(+)

aVL = (RA-LL) vs. LA(+)


ECG Recordings (QRS Vector pointing leftward, inferiorly

& posteriorly)

3 Bipolar Limb Leads:

RA

LA

I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

3 Augmented Limb Leads:

LL

aVR = (LA-LL) vs. RA(+)

aVL = (RA-LL) vs. LA(+)

aVF = (RA-LA) vs. LL(+)


6 PRECORDIAL (CHEST) LEADS

Spine

V6

V5

Sternum

V4

V3

V1

V2


ECG Recordings: (QRS vector---leftward, inferiorly and posteriorly

3 Bipolar Limb Leads

I = RA vs. LA(+)

II = RA vs. LL(+)

III = LA vs. LL(+)

3 Augmented Limb Leads

aVR = (LA-LL) vs. RA(+)

aVL = (RA-LL) vs. LA(+)

aVF = (RA-LA) vs. LL(+)

6 Precordial (Chest) Leads: Indifferent electrode (RA-LA-LL) vs.

chest lead moved from position V1 through position V6.


THE CARDIAC CYCLE

LATE DIASTOLE

DIASTOLE

ISOMETRIC

VENTRICULAR

RELAXATION

ATRIAL

SYSTOLE

VENTRICULAR

EJECTION

ISOMETRIC VENTRICULAR

CONTRACTION


EJECTION

ISOVOLUMETRIC

CONTRACTION

ISOVOLUMETRIC RELAXATION

RAPID INFLOW

DIASTASIS

ATRIAL SYSTOLE

AORTIC

PRESSURE

PRESSURE (mmHg)

ATRIAL

PRESSURE

VENTRICLE

PRESSURE

VOLUME (ml)

ECG

PHONO-

CARDIOGAM

SYSTOLE DIASTOLE SYSTOLE


MEASUREMENT OF CARDIAC OUTPUT

THE FICK METHOD:

VO2 = ([O2]a - [O2]v) x Flow

Spirometry (250 ml/min)

VO2

[O2]a - [O2]v

Flow =

Pulmonary Artery Blood (15 ml%)

Arterial Blood (20 ml%)

CARDIAC OUTPUT

PULMONARY BLOOD FLOW

VENOUS RETURN

PERIPHERAL

BLOOD FLOW


.

VO2

[O2]a - [O2]v

CARDIAC OUTPUT (Q) =

250 ml/min

20 ml% - 15 ml%

=

= 5 L/min

.

Q = HR x SV

.

.

Q

m2 body surface

area

Q

HR

CARDIAC INDEX =

SV =

5 L/min

70 beats/min

=

5 L/min

1.6 m2

=

= 0.0714 L or 71.4 ml

= 3.1 L/min/m2


The heart as a pump
THE HEART AS A PUMP

  • REGULATION OF CARDIAC OUTPUT

    • Heart Rate via sympathetic & parasympathetic nerves

    • Stroke Volume

      • Frank-Starling “Law of the Heart”

      • Changes in Contractility

  • MYOCARDIAL CELLS (FIBERS)

    • Regulation of Contractility

    • Length-Tension and Volume-Pressure Curves

    • The Cardiac Function Curve


Autoregulation

(Frank-Starling “Law of the Heart”)

CARDIAC OUTPUT = STROKE VOLUME x HEART RATE

Contractility

Sympathetic

Nervous System

Parasympathetic

Nervous System


CARDIAC MUSCLE

- Functional Syncytium

- Automaticity

STRIATED MUSCLE

SKELETAL MUSCLE

- Motor Units

- Stimulated by Motor Nerves


STRUCTURE OF A MYOCARDIAL CELL

Sarcolemma

Mitochondria

T-tubule

SR

Fibrils


SARCOLEMMA

10%

Mitochondria

20%

80%

T-tubule

Ca++

SR

THICK

MYOFILAMENT

THIN MYOFILAMENT


Regulataion of contractility
REGULATAION OF CONTRACTILITY

  • Recruitment of motor units

  • Increase frequency of firing of motor nerves

  • Calcium to trigger contraction


Increasing heart rate increases contractility
INCREASING HEART RATE INCREASES CONTRACTILITY

Ca++

Ca++

Normal

Heart Rate

Fast

Heart Rate

Ca++

Ca++

Ca++

Ca++


SERIES ELASTIC ELEMENTS

CONTRACTILE COMPONENT

(ACTIVE TENSION)

PARALLEL ELASTIC ELEMENTS

(PASSIVE TENSION)

TOTAL TENSION


LENGTH-TENSION CURVE

TOTAL TENSION

ACTIVE TENSION

TENSION

PASSIVE TENSION

OPTIMAL LENGTH (Lo)

EQUILIBRIUM LENGTH

RESTING LENGTH

LENGTH

LENGTH


TENSION

SARCOMERE LENGTH ()


CARDIAC MUSCLE

TOTAL TENSION

ACTAIVE TENSION

TENSION

PASSIVE

TENSION

MUSCLE LENGTH


HEART

SYSTOLIC PRESSURE CURVE

Isotonic (Ejection) Phase

After-load

Isovolumetric

Phase

PRESSURE

Stroke

Volume

DIASTOLIC

PRESSURE CURVE

Pre-load

End Systolic Volume

End Diastolic Volume


HEART

INCREASED

CONTRACTILITY

SYSTOLIC PRESSURE CURVE

Isotonic (Ejection) Phase

After-load

Isovolumetric

Phase

PRESSURE

Stroke

Volume

DIASTOLIC

PRESSURE CURVE

Pre-load

End Systolic Volume

End Diastolic Volume


HEART

DECREASED

CONTRACTILITY

SYSTOLIC PRESSURE CURVE

Isotonic (Ejection) Phase

After-load

Isovolumetric

Phase

PRESSURE

Stroke

Volume

DIASTOLIC

PRESSURE CURVE

Pre-load

End Systolic Volume

End Diastolic Volume


HEART

INCREASED

FILLING

SYSTOLIC PRESSURE CURVE

Isotonic (Ejection) Phase

After-load

Isovolumetric

Phase

PRESSURE

Stroke

Volume

DIASTOLIC

PRESSURE CURVE

Pre-load

End Systolic Volume

End Diastolic Volume


Cardiac function curve
CARDIAC FUNCTION CURVE

Cardiac Output = Stroke Volume x Heart Rate

Constant

If:

STROKE VOLUME

Then:

 CO reflects SV

DIASTOLIC FILLING

Right Atrial Pressure (RAP) reflects Diastolic Filling


Cardiac function curve1
CARDIAC FUNCTION CURVE

THE FRANK- STARLING “LAW OF THE HEART”

15-

10-

CARDIAC OUTPUT (L/min)

Pressure

5-

Volume

-4

0

+4

+8

RAP mmHg


Cardiac function curve2
CARDIAC FUNCTION CURVE

THE FRANK- STARLING “LAW OF THE HEART”

15-

Increased

Contractility

10-

CARDIAC OUTPUT (L/min)

5-

-4

0

+4

+8

RAP mmHg


Cardiac function curve3
CARDIAC FUNCTION CURVE

THE FRANK- STARLING “LAW OF THE HEART”

15-

Decreased

Contractility

10-

CARDIAC OUTPUT (L/min)

5-

-4

0

+4

+8

RAP mmHg


Cardiac function curve4
CARDIAC FUNCTION CURVE

THE FRANK- STARLING “LAW OF THE HEART”

15-

Increased

Heart Rate

10-

CARDIAC OUTPUT (L/min)

5-

-4

0

+4

+8

RAP mmHg


Cardiac function curve5
CARDIAC FUNCTION CURVE

THE FRANK- STARLING “LAW OF THE HEART”

15-

Decreased

Heart Rate

10-

CARDIAC OUTPUT (L/min)

5-

-4

0

+4

+8

RAP mmHg


P1 > P2

P1

FLOW

P2

mm Hg

P = FLOW x R

P

R

FLOW =

P

FLOW

R =

L/min

or

ml/sec

mm Hg

ml/sec

Peripheral Resistance Units (PRU)


Laminar or streamline flow
LAMINAR or STREAMLINE FLOW

P1

P2

P1 > P2

-Cone Shaped Velocity Profile

-Not Audible with a Stethoscope


MEASURING BLOOD PRESSURE

TURBULENT FLOW

1. Cuff pressure > systolic blood pressure--No sound.

2. The first sound is heard at peak systolic pressure.

3. Sounds are heard while cuff pressure < blood pressure.

4. Sound disappears when cuff pressure < diastolic pressure.


Resistances in series
RESISTANCES IN SERIES

RT = RA + RC + RV

RESISTANCES IN PARALLEL

FlowT = Flow1 + Flow2 + Flow3

P

RT

P

R1

P

R2

P

R3

=

+

+

R1

PV

PA

1

RT

1

R1

1

R2

1

R3

R2

=

+

+

R3

1

RT

=

1

R1

1

R2

1

R3

+

+


If: R1 = 2; R2 = 4; R3 = 6 PRU’s

Then a series arrangement gives:

RT = R1 + R2 + R3

RT = 12 PRU’s

But a parallel arrangement gives:

RT = =1.94 PRU’s

1

1

R1

1

R2

1

R3

+

+


Poiseuille's Law

v = Pr2 /8l

P

R

Flow =

Q = vr2

Pr4

8l

Q =

R = 8l/r4


Total peripheral resistance
TOTAL PERIPHERAL RESISTANCE

SYSTEMIC CIRCULATION:

Aortic Pressure - RAP

FLOW

TPR =

100 - 0 mmHg

83.3 ml/sec (5 L/min)

= 1.2 PRU’s

TPR =

PULMONARY CIRCULATION:

Pul. Art. P. - LAP

FLOW

Pul. R. =

15 - 5 mmHg

83.3 ml/sec

Pul. R. =

= 0.12 PRU’s


Vascular compliance
VASCULAR COMPLIANCE

V

P

C =

Arteries

250 ml

100 mmHg

Ca = =2.5 ml/mmHg

100-

Sym

300 ml

5 mmHg

Cv = = 60 ml/mmHg

Sym

Cv = 24 x Ca

PRESSURE (mmHg)

Veins

Sym

Sym

1

4

2

3

VOLUME (L)


Mean circulatory pressure
MEAN CIRCULATORY PRESSURE

Unstressed

Volume

Stressed Volume

7-

PRESSURE (mmHg)

MCP = 7 mmHg

1 2 3 4 5 6

VOLUME (L)


Capillaries
CAPILLARIES

  • Pressure inside is 35 to 15 mmHg

  • 5% of the blood is in capillaries

  • exchange of gases, nutrients, and wastes

  • flow is slow and continuous


Arteriole

?

Precapillary

Sphincters

Capillaries

Metarteriole

Venule


VASOMOTION = Intermittent flow due to constriction-

relaxation cycles of precapillary shpincters

or arteriolar smooth muscle (5 - 10/min)

AUTOREGULATION OF VASOMOTION:

1. Oxygen Demand Theory (Nutrient Demand Theory)

O2 is needed to support contraction (closure)

2. Vasodilator Theory

Vasodilator substances produced (via  O2)

e.g. Adenosine  Heart

CO2  Brain

Lactate, H+, K+  Skeletal Muscle

3. Myogenic Activity


DIFFUSION BETWEEN BLOOD & INTERSTITIAL FLUID

Plasma Proteins

BLOOD

INTERSTITIAL

FLUID

O2

CO2

Glucose

active transport

CELL


FLUID BALANCE

Filtration vs. Reabsorption

40-

30-

20-

10-

0-

Outward Forces:

1. Capillary blood pressure

(Pc = 35 to 15 mmHg)

2. Interstitial fluid pressure

(PIF = 0 mmHg)

3. Interstitial fluid colloidal

osmotic pressure

(IF = 3 mmHg)

TOTAL = 38 to 18 mmHg

PRESSURE (mmHg)

Inward Force:

1. Plasma colloidal osmotic

pressure (C = 28 mmHg)


Capillary fluid shift
CAPILLARY FLUID SHIFT

Pout > c Pout < c

Pc

Pc

FAVORS FILTRATION

FAVORS REABSORPTION

PULMONARY CIRCULATION


FLUID BALANCE

Filtration vs. Reabsorption

40-

30-

20-

10-

0-

Via

lymphatics

PRESSURE (mmHg)

Filtration Reabsorption

RADIAL FLOW


LYMPHATIC CAPILLARY

2 - 4 L/day ( 125 ml/hr)

“PUMP”

Compression

Smooth muscle contraction

Anchoring Filaments


Effects of gravity on arterial and venous pressures.

Each cm of distance produces a 0.77 mmHg change.

Veins Arteries

0

100 mm Hg

190 mm Hg

Sphincters protect

capillaries

VENOUS PUMP keeps PV < 25 mm Hg


HEART

 Art. BP

CO = PBF

VEINS

(RAP)

ARTERIES

 RAP

7 mmHg 

7 mmHg

Peripheral Blood Flow


RELATIONSHIP BETWEEN RAP and PBF

Cv = 24 x CaP

RAP Pv PaP= Pa - Pv TPR PBF=TPR

(mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec)

7 7 7 0 1.2 0

6 31 25 1.2 20.8

5 55 50 1.2 41.7

4 79 75 1.2 62.5

0 3 103 100 1.2 83.3 (5 L/min)


THE VASCULAR FUNCTION CURVE

10-

5-

0-

PBF

or

VENOUS

RETURN

(L/min)

-4 0 +4 +8

RAP (mmHg)


Ways to alter the vascular function curve
WAYS TO ALTER THE VASCULAR FUNCTION CURVE

  • CHANGE THE MEAN CIRCULATORY PRESSURE

    • CHANGE BLOOD VOLUME

    • CHANGE VENOUS CAPACITY

  • CHANGE TOTAL PERIPHERAL RESISTANCE


  • Mean circulatory pressure1
    MEAN CIRCULATORY PRESSURE

    Unstressed

    Volume

    Stressed Volume

    Infusion

     VOLUME

     MCP

    Normal

    7-

    PRESSURE (mmHg)

     VOLUME

     MCP

    Hemorrhage

    1 2 3 4 5 6

    BLOOD VOLUME (L)


    Mean circulatory pressure2
    MEAN CIRCULATORY PRESSURE

    VENOCONSTRICTION

    Unstressed

    Volume

    Stressed Volume

    Normal

    7-

    PRESSURE (mmHg)

    1 2 3 4 5 6

    BLOOD VOLUME (L)


    Mean circulatory pressure3
    MEAN CIRCULATORY PRESSURE

    VENODILATION

    Unstressed

    Volume

    Stressed Volume

    Normal

    7-

    PRESSURE (mmHg)

    1 2 3 4 5 6

    BLOOD VOLUME (L)


    RELATIONSHIP BETWEEN RAP and PBF

    Cv = 24 x CaP

    RAP Pv PaP= Pa - Pv TPR PBF=TPR

    (mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec)

    7 7 7 0 1.2 0

    6 31 25 1.2 20.8

    5 55 50 1.2 41.7

    4 79 75 1.2 62.5

    0 3 103 100 1.2 83.3 (5 L/min)

    8 8 8 0 1.2 0

    7 32 25 1.2 20.8

    6 56 50 1.2 41.7

    5 80 75 1.2 62.5

    4 104 100 1.2 83.3 (5 L/min)

    0 3 128 125 1.2 104.2 (6.25 L

    min

     MCP


    THE VASCULAR FUNCTION CURVE

    10-

    5-

    0-

     Blood Volume

    or

    Venoconstriction

    PBF

    or

    VENOUS

    RETURN

    (L/min)

     MCP

     MCP

     Blood Volume

    or

    Venodilation

    -4 0 +4 +8

    RAP (mmHg)


    RELATIONSHIP BETWEEN RAP and PBF

    Cv = 24 x CaP

    RAP Pv PaP= Pa - Pv TPR PBF=TPR

    (mmHg) (mmHg) (mmHg) (mmHg) (PRU’s) (ml/sec)

    7 7 7 0 1.2 0

    6 31 25 1.2 20.8

    5 55 50 1.2 41.7

    4 79 75 1.2 62.5

    0 3 103 100 1.2 83.3 (5 L/min)

    7 7 7 0 2.0 0

    6 31 25 2.0 12.5

    5 55 50 2.0 25.0

    4 79 75 2.0 37.5

    0 3 103 100 2.0 50.0 (3 L/min)

     TPR


    THE VASCULAR FUNCTION CURVE

    Vasodilation

    10-

    5-

    0-

    PBF

    or

    VENOUS

    RETURN

    (L/min)

     TPR

     TPR

    Vasoconstriction

    -4 0 +4 +8

    RAP (mmHg)


    Cardiac vascular function curves
    CARDIAC & VASCULAR FUNCTION CURVES

    15-

    CARDIAC

    OUTPUT

    or

    PERIPHERAL

    BLOOD FLOW

    [Venous Return]

    (L/min)

    10-

    5-

    -4

    0

    +4

    +8

    RAP mmHg


    Changes in cardiovascular performance
    CHANGES IN CARDIOVASCULAR PERFORMANCE

    BY ALTERING THE CARDIAC FUNCTION CURVE

    - CHANGING CONTRACTILITY

    - CHANGING HEART RATE

    BY ALTERING THE VASCULAR FUNCTION CURVE

    - CHANGING MEAN CIRCULATORY PRESSURE

    Blood Volume

    Venous Capacity

    - CHANGING TOTAL PERIPHERAL RESISTANCE


    MOTOR CORTEX

    HYPOTHALAMUS

    Sympathetic

    Nervous

    System

    Chemosensitive Area

    VASOMOTOR CENTER

    PRESSOR AREA

    DEPRESSOR AREA

    CARDIOINHIBITORY AREA

    Glossopharyngeal

    Nerve

    Vagus

    Baroreceptors

    Carotid Sinus

    Aortic Arch

    HEART

    Arterioles

    Veins

    Adrenal

    Medulla

    Chemoreceptors

    Carotid Bodies

    Aortic Bodies

    Bainbridge Reflex ( Heart Rate)

    Atrial Receptors Volume Reflex ( Urinary OUTPUT)

    a.  Vascular Sympathetic Tone

    b.  ADH Secretion

    c.  Aldosterone Secretion


    RENIN-ANGIOTENSIN-ALDOSTERONE MECHANISM

    Angiotensinogen (renin substrate)

    Angiotensin

    Aldosterone

    Kidney

    sodium & water retention

     BP (Kidney)

    Renin

    Vasoconstriction

    Venoconstriction


    Hormonal regulation
    HORMONAL REGULATION

    • Epinephrine & Norepinephrine

      • From the adrenal medulla

    • Renin-angiotensin-aldosterone

      • Renin from the kidney

      • Angiotensin, a plasma protein

      • Aldosterone from the adrenal cortex

    • Vasopressin (Antidiuretic Hormone-ADH)

      • ADH from the posterior pituitary


    VASOPRESSIN

    (ANTIDIURETIC HORMONE)

    Hypothalamic

    Osmoreceptors

     BP via Posterior Pituitary  Vasopressin (ADH)

    (Atrial Receptors)

    Vasoconstriction  Water

    Venoconstriction Retention

    X

    X


    Renal body fluid control mechanism
    RENAL--BODY FLUID CONTROL MECHANISM

    -8

    -7

    -6

    -5

    -4

    -3

    -2

    -1

    8-

    7-

    6-

    5-

    4-

    3-

    2-

    1-

    All Mechanisms

    Uninary

    Output

    (x normal)

    Fluid

    Intake

    (x normal)

    3 x Normal

    P alone

    Normal

    50 100 150

    ARTERIAL BLOOD PRESSURE (mmHg)


    Hypertension 140 90 mmhg
    HYPERTENSION (140/90 mmHg)

    Secondary Hypertension (10%) [e.g., Pheochromocytoma]

    Essential Hypertension (90%)

    - Normal cardiac output

    - Cardiac hypertrophy [left ventricle]

    - “Resetting” of the baroreceptors

    - Thickening of vascular walls

    ARTERIAL PRESSURE-URINARY OUTPUT THEORY

    Hypertension causes thickening of vascular walls

    NEUROGENIC THEORY

    Thickening of vascular walls causes hypertension

    TREATMENT: Reduce stress

    Sympathetic blockers

    Low sodium diet

    Diuretics


    Hemorrhage
    HEMORRHAGE

    7-

    MCP

    CO

    or

    PBF

    (L/min)

    CO

    BP

    Pressure

    1 2 3 4 5

    Blood Volume (L)

    -4 0 +4 +8

    RAP (mmHg)


    Cardiac vascular function curves1
    CARDIAC & VASCULAR FUNCTION CURVES

    15-

    CARDIAC

    OUTPUT

    or

    PERIPHERAL

    BLOOD FLOW

    [Venous Return]

    (L/min)

    10-

    Response to Hemorrhage

     HR & Contractility

    Venoconstriction ( MCP)

    Vasoconstriction ( TPR)

    5-

    -4

    0

    +4

    +8

    RAP mmHg


    Response to hemorrhage
    RESPONSE TO HEMORRHAGE

    •  Sympathetic tone via baroreceptor reflex

      •  Heart rate and contractility

      • Venoconstriction ( MCP)

      • Vasoconstriction ( arterial BP & direct blood to vital organs)

    • Restore Blood Volume

      • Capillary fluid shift ( BP favors reabsorption)

      •  Urinary output ( Arterial BP, ADH, Renin-Angiotensin-Aldosterone)

    • Restore plasma proteins & hematocrit


    SYNCOPE (FAINTING)Postural syncope(Blood pooling in the extremities) Vasovagal syncopeCarotid sinus syncope


    Syncope fainting blood pooling in the extremities
    SYNCOPE (FAINTING)Blood pooling in the extremities

    Unstressed

    Volume

    Stressed Volume

    Normal

    7-

     Unstressed Vol.

     Stressed Vol.

     MCP

    PRESSURE (mmHg)

    Syncope (Fainting)

    1 2 3 4 5 6

    BLOOD VOLUME (L)


    Syncope fainting blood pooling in the extremities1
    SYNCOPE (FAINTING)Blood pooling in the extremities

    7-

    MCP

    CO

    or

    PBF

    (L/min)

    CO

    BP

    Pressure

    1 2 3 4 5

    Blood Volume (L)

    -4 0 +4 +8

    RAP (mmHg)


    Cardiac vascular function curves2
    CARDIAC & VASCULAR FUNCTION CURVES

    15-

    CARDIAC

    OUTPUT

    or

    PERIPHERAL

    BLOOD FLOW

    [Venous Return]

    (L/min)

    10-

    Response to Syncope (Fainting

     HR & Contractility

    Venoconstriction ( MCP)

    Vasoconstriction ( TPR)

    5-

    -4

    0

    +4

    +8

    RAP mmHg


    Cardiac failure
    CARDIAC FAILURE

    • CAUSES: Impairment of electrical activity

    • Muscle damage

    • Valvular defects

    • Cardiomyopathies

    • Result of drugs or toxins

    • PROBLEM: Maintaining circulation with a weak pump

    • ( Cardiac output & cardiac reserve;  RAP)

    • SOLUTIONS: Sympathetic tone via baroreceptor reflex

    • - Heart rate and contractility

      • -Venoconstriction ( MCP)

      • -Vasoconstriction ( Arterial BP)

      • Fluid retention ( MCP)

      • -Capillary fluid shift

      • -ADH

      • -Renin-angiotensin-aldosterone


    Cardiac vascular function curves3
    CARDIAC & VASCULAR FUNCTION CURVES

    15-

    CARDIAC

    OUTPUT

    or

    PERIPHERAL

    BLOOD FLOW

    [Venous Return]

    (L/min)

    SYMPTOMS:

    Systemic Edema

    Pulmonary

    Congestion

    Enlarged Heart

    10-

    Adjustments to Failure

    5-

    Cardiac Failure

    -4

    0

    +4

    +8

    RAP mmHg


    HEART

    CARDIAC

    FAILURE

    SYSTOLIC PRESSURE CURVE

    Isotonic (Ejection) Phase

    After-load

    Isovolumetric

    Phase

    PRESSURE

    Stroke

    Volume

    DIASTOLIC

    PRESSURE CURVE

    Pre-load

    End Systolic Volume

    End Diastolic Volume


    Temperature regualtion
    TEMPERATURE REGUALTION

    • Body Temperature

    • Heat Production

    • Heat Loss

    • Temperature Regulation

      • Heat Exhaustion

      • Heat Stroke

      • Hypothermia

    • Fever


    COLD

    WARM


    Temperature

    regulation

    seriously

    impaired

    Temperature

    regulation

    efficient in

    febrile disease

    health and work

    Temperature

    regulation

    impaired

    Temperature

    regulation

    lost

    Upper limit of survival?

    Heat stroke

    Brain lesions

    Fever therapy

    Febrile disease

    and

    Hard exercise

    Usual range of normal

    Lower limit

    of survival?


    Heat production
    HEAT PRODUCTION

    BASAL METABOLIC RATE

    - Catecholamines

    -Hyperthyroidism

    FOOD INTAKE (Specific Dynamic Action)

    -lasts up to 6 hours after a meal

    PHYSICAL ACTIVITY

    -Exercise (20 x BMR)

    -Shivering (5 x BMR)


    Heat loss
    HEAT LOSS

    COOLHOT

    RADIATION

    CONDUCTION 70% 

    CONVECTION

    VAPORIZATION 30% 

    Insensible Water Loss * *

    Sweating *


    SKINHYPOTHALAMUS

    Preoptic Area

    Sweating

    Vasodilation

    W

    Set

    point

    Warm

    Receptors

    Cold

    Receptors

    W

    Vasoconstriction

    Shivering

    W

    C


    Interaction between peripheral central sensors
    Interaction Between Peripheral & Central Sensors

    Cooling the skin raises the set point above which sweating begins.

    Warm skin--sweating occurs above 36.7C

    Cold skin--sweating occurs above 37.4 C

    The body is reluctant to give off heat (sweat) in a cold environment.

    Warming the skin lowers the set point below which shivering begins.

    Cold skin: shivering occurs at 37.1C

    Warm skin: shivering occurs at 36.5C

    The body is reluctant to produce heat (shiver) in a warm environment.


    Limits to temperature regulation
    LIMITS TOTEMPERATURE REGULATION

    Heat Exhaustion: Inadequate water/salt replacement

    Body temperature may be normal

    Symptoms: cerebral dysfunction

    nausea

    fatique

    Vasodilaton causing fatigue or fainting

    Heat Stroke: Temperature regulation lost

    Symptoms: high body temperature

    NO sweating

    dizziness or

    loss of consciousness

    Body temperature MUST be lowered!


    Fever
    FEVER

    FEVER = an abnormally high body temperature

    PYROGEN = a fever producing substance

    PYROGEN WBC

    bacterial toxins, leukocytes,

    viruses, pollen, + monocytes = endogenous pyrogen

    proteins, dust

    Arachidonic Acid

    Prostaglandins Aspirin

    RAISES THE “SET POINT”


    Shivering

    Vasoconstriction

    Sweating

    Vasodilation

    Reference

    Temperature

    or Set Point

    Actual Core

    Temperature

    Fever

    Breaks

    Onset of

    Fever


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