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8/13/2019 Pengendalian TekananDarah

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Rapid Control of ArterialPressure by Nervous System

By:

M. Rasjad Indra

Lab. Ilmu Faal FK UNIBRAW


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Pengendalian sirkulasi oleh sistem

saraf

Peran sistem saraf dalam pengendalian

aliran darah lokal sangat kecil.

Sistem saraf lebih berperan pada fungsi

global dalam hal:

1. Pendistribusian darah ke area tubuh tertentu

2. Kekuatan pompa jantung

3. Pengendalian cepat tekanan darah


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Three Major Changes

If sympathetic nervous system are stimulated

1.Almost all arterioles are constricted Increases the total peripheral resistance

2. The veins especially & other large vessels arestrongly constricted Increases venous returnincrease cardiac out put

(Starling Law)

3. The heart enhancing cardiac pumping Increases heart rate

Increases cardiac contractility


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Anestesi spinal menyebabkan penurunan tekanan darah akibat

hilangnya tonus vasomotor


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Reflex Mechanism for Maintaining

Normal Arterial Pressure

Baroreceptor Reflexes:

The receptors: Baroreceptors or PressoreceptorsLocated in the wall of several of large systemic

arteriesSinus caroticus n. Hering n. Glossopharyngeustr. Solitarius Med. Oblongata.

Arcus aortae n. Vagus

The Response: Feedback signals to reducearterial pressure(blood pressure)Vasodilatation of the veins and arterioles

Decreased heart rate & the strength of heartcontraction


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Efek perubahan tekanan arteri (P) terhadap perubahan transmisi impuls n.Hering dari sinus Caroticus I)Baroreseptor lebih merespons perubahan tekanan daripada tekanan stasioner


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Penjepitan a. carotis communis menyebabkan peningkatan tekananarteri (MAP), pelepasan jepitan menurunkan tekanan arteri


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Function of Baroreceptor Reflex

During changes in Body Posture

To maintain relatively constant arterialpressure in the upper body

Pressure BufferFunction Opposes either increasesor decreasesin

arterial pressure.

Unimportance of Baroreceptor System forLong Regulation

The resetting of baroreceptor systems


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Pencatatan tekanan darah selama 2 jam pada kondisi NORMAL (gambar atas)

dan pada beberapa minggu setelah DENERVASI sinus caroticus

dan Sinus aorticus


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Frekuensi distribusi MAP selama 24 jam pada anjing NORMAL dan beberapa

minggu setelah denervasi baroreseptor


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Chemoreceptors Reflex: The receptors sensitive to:

Lack of oxygens; CO2excess and H+excess.

Located in the wall of small arteries; Carotid Bodies & Aortic

Bodies.

Not a powerful control in a normal arterial pressure

range

Important in below 80 mmHg

Low-pressure Receptors: Stretch receptors

Located in the wall of: Pulmonary arteries & Atrium

Role: to minimize arterial pressure changes in

response to changes in blood volume.

Reflex Mechanism for Maintaining Normal

Arterial Pressure (Cont.)


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Volume Reflex (Atrial Reflex that Activate the Kidney)

Stimulation: Stretch of the atria

Response:

1.Dilatation of the afferent arteriole in the kidney2.To HypothalamusDecrease ADH secretion

3.Release of Atrial Natriuretic Peptide (ANP)

The Bainbridge Reflex (x baro)

Stimulation: Stretch of the atria

Response: n. VagusMed. OblongataIncrease the

heart rate & strength of the heart contraction

Reflex Mechanism for Maintaining

Normal Arterial Pressure (Cont.)


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CA

CI

HIGHER CENTER

VASOMOTOR

CENTER

CI CA

JANTUNG

SV Hr

C.O.PX

TPR

Blood Pressure

O2

H

CO2

PH

CHEMORECEPTOR

+

VCVD

+

Baroreceptor

-

BARORESEPTOR

CONTROL Blood Pressure

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