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PENGENDALIAN ALIRAN DAN TEKANAN DARAH
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Local Control of Blood Flow
Introduction
The greater the metabolism the greater its blood flow– Liver: 95 ml/min/100 g of liver tissue.– Kidneys: 1100 ml/min cleansing the
blood. The importance of blood flow control
effective & efficient– Serving metabolic need– Efficient heart workload.
Mechanism of Blood Flow Control
Acute control (rapid changes in local vasodilatation / vasoconstriction):– Effect of tissue metabolism– The availability of oxygen changes.– Two basic theories:
Vasodilator theory: adenosine; CO2; histamine; K+ & H+
Oxygen lack theory: vasomotion in metarterioles & precapillary sphincters.
– Other nutrients besides Oxygen:– Lack of glucose vasodilatation– Vitamin B deficiency vasodilatation
The examples of acute metabolic control of local blood
flow1. Reactive hyperemia
• Blocked (seconds – hours) unblocked• Blood flow increases to 4 – 7 times
normal• Depend on how long it is blocked.
2. Active hyperemia• Tissue activity lack of nutrient &
release vasodilator substances.• Local blood flow increases 20 times in
muscle during heavy exercise.
Blood flow control & The arterial pressure changes
Acute autoregulation theory:1. The metabolic theory2. The myogenic theory (still doubtful !!)
Endothelial-Derived Relaxing Factor “EDRF” (NO):
– Rapid flow of blood shear stress NO release relaxes the local arterial wall.
Long Term Blood Flow Regulation
1. Change in Tissue Vascularity– Reconstruction to meet the needs of
the tissues– Role of Oxygen in Long-Term
Regulation.– Vascular Endothelial Growth Factors:
1. VEGF2. FGF3. Angiogenin
2. Collateral Circulation:
Humoral Regulation of The Circulation
1. Vasoconstrictor Agents:1. Norepinephrine & Epinephrine2. Angiotensin3. Vasopressin4. Endothelin
2. Vasodilator Agents:1. Bradikynin2. Histamin
3. Effects of Ion & Other Chemical Factors1. Calcium vasoconstriction2. Potasium Vasodilatation3. Magnesium powerful vasodilatation4. Hydrogen vasodilatation5. Acetate & Citrate mild degree
vasodilatation
Rapid Control of Arterial Pressure by
Nervous System
TIM BLOK CARDIOVASKULER
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 jantung3. Pengendalian cepat tekanan darah
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 are strongly constricted• Increases venous return increase cardiac out
put (Starling Law)
3. The heart enhancing cardiac pumping• Increases heart rate• Increases cardiac contractility
Anestesi spinal menyebabkan penurunan tekanan darah akibat hilangnya tonus vasomotor
Reflex Mechanism for Maintaining Normal Arterial Pressure
Baroreceptor Reflexes:– The receptors: Baroreceptors or
Pressoreceptors Located in the wall of several of large systemic
arteries Sinus caroticus n. Hering n.
Glossopharyngeus tr. Solitarius Med. Oblongata.
Arcus aortae n. Vagus– The Response: Feedback signals to reduce
arterial pressure Vasodilatation of the veins and arterioles Decreased heart rate & the strength of heart
contraction
Efek perubahan tekanan arteri (ΔP) terhadap perubahan transmisi impuls n. Hering dari sinus Caroticus (ΔI)
Baroreseptor lebih merespons perubahan tekanan daripada tekanan stasioner
Penjepitan a. carotis communis menyebabkan peningkatan tekanan arteri (MAP), pelepasan jepitan menurunkan tekanan arteri
Function of Baroreceptor Reflex
During changes in Body Posture– To maintain relatively constant arterial
pressure in the upper body Pressure Buffer Function
– Opposes either increases or decreases in arterial pressure.
Unimportance of Baroreceptor System for Long Regulation– The resetting of baroreceptor systems
Pencatatan tekanan darah selama 2 jam pada kondisi NORMAL (gambar atas) dan pada beberapa minggu setelah DENERVASI sinus caroticus dan Sinus aorticus
Frekuensi distribusi MAP selama 24 jam pada anjing NORMAL dan beberapa minggu setelah denervasi baroreseptor
Chemoreceptors Reflex:– The receptors sensitive to:
Lack of oxygens; CO2 excess 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.)
Volume Reflex (Atrial Reflex that Activate the Kidney)– Stimulation: Stretch of the atria– Response:
1.Dilatation of the afferent arteriole in the kidney2.To Hypothalamus Decrease ADH secretion 3.Release of Atrial Natriuretic Peptide (ANP)
The Bainbridge Reflex– Stimulation: Stretch of the atria– Response: n. Vagus Med. Oblongata Increase
the heart rate & strength of the heart contraction
Reflex Mechanism for Maintaining Normal Arterial Pressure (Cont.)
CA
CI
HIGHER CENTER
VASOMOTORCENTERCI CA
JANTUNG
SV Hr
C.O.PX
TPR
“Blood Pressure”O2
H
CO2
PH
CHEMORECEPTOR
+
VCVD
+
“Baroreceptor”
-
BARORESEPTORCONTROL “Blood Pressure”
TEKANAN DARAH
C.O.P T.P.R
S.V Hr
EDV
IVFP
VR
VC
BV
VD
ESV
MC
SK
CPM
S
PS
PEGVMC
LVMC
VK/VD
NEUROHUMO-RAL CONTROL
BHN LOKALO2,CO2,H,K
EMP
B.VISC.
HT
FAKTOR YG MEMPENGARUHI “BP”
KONTROL TEK. DARAH SISTIM SARAF:
CNS : VASOMOTORCENTER ( CA & CI ) LUAR CNS: “BR” & “CR”
SISTIM HUMORAL / KIMIA / HORMON: RENIN-ANGIOTENSIN, ALDOSETRON, VASOPRESIN ADRENALIN, NOR ADRENALIN, ACETYLKOLIN K, Mg, H, Ca, Na, CO2,CO, ROS, LAKTAT,
PYRUVAT. SISTIM HEMODINAMIK:
VOLUME DARAH & TEK. OSMOTIK/HIDROSTATIK Pada sistim ini lebih banyak dipengaruhi oleh
perubahan-2 tek hidrostatik, osmotik & oncotik yg terdapat diluar dan didalam sistim vaskuler
Mekanismenya berjalan secara simultan & saling melengkapi & Tujuannya: menunjang “homeostatics”
BRAINSTRESS STRESS PSIKOLOGIFISIKSUHUTOXIN
HIPOTHALAMUS
REAKSI HORMONAL REAKSI NEURAL
VASOPRESIN CRF
RETENSI Na & H2O
VMC SIMPATIS
HEART VASKULER
INOTROPIK, EDVVENT.DIST,FILLING P
CPM
SV X Hr
COP “R”X
“BP”
BV
VASOKONS-TRIKSI
JGA
RENINANGIOTENSINOGEN+ ANGIOTENSIN I
CONVERTING ENZYM
ANGIOTENSIN II PARU
LIVER
ADRENAL CORTEX
ALDOSTERON BRAINVMC
Intake H2O
“S”retensi Na
& H2O
BV JANTUNG
ARTERI
GLOMERULUS
VASOKONSTRIKSI
RCOP
“BP”
SVHr
RBF
RENIN-ANGIOTENSINCONTROL”BP”
x
CA
CI
HIGHER CENTER
VASOMOTORCENTERCI CA
JANTUNG
SV Hr
C.O.PX
TPR
“BP”O2
H
CO2
PH
CHEMORECEPTOR
+
VKVD
+“BR”
-
BARORESEPTORCONTROL “BP”
SHORTTERM CONTROL “BP” VIA BARORECEPTOR REFLEX
F:CARDIACPHYSIOLOGY/CHAP.18B/IBNU/NEW/PAPI/CARDIOVASKULERPHYSIOLOGY/2004
KELAINAN TEK. DARAH HIPERTENSI: Tek.darah melebihi nilai nor-
malnya. N Bp: 120/80 & MAP=93,33 mmHg misalnya : 130/95 mmHg atau lebih besar.
HIPOTENSI : Tek. Darah kurang dari nilai nor- malnya.Biasanya ada hub.nya dengan shock! Misalnya: 80-90/60- 55 mmHg atau lebih kecil.
KLASIFIKASI HIGH BLOOD PRESSURE : Hipertensi essensiil: penyebab tak jelas, mungkin
karena kacaunya sistim kontrolnya (saraf,hemodinamik,humoral)
Hipertensi skunder: penyebab jelas, ada kelainan organ seperti peny. ginjal; tumor cortex adrenalis;toximia gravidarum;obat
Klasifikasi lain: Hipertensi ringan, Hipertensi sedang dan Hipertensi berat
HIPERTENSI ESSENSIILFAKTOR
Genetik,makanan;minumanEmosi & stress psikosial; obat; merokok; olah raga
Pemicu fisiogenesis:
Kacau sistim kontrol“Bp” (neural,hemodinamik
& humoral)
Ht .Ess
Ubah “life style”
Cara mengatasi
Tdk merokok
Tdk minum alkohol
Kurangi makan garam
OR Hilangkan stress
Tidur cukup
Health Wellness
Stop obat
Obat anti hipertensi2
1
HIPERTENSI SKUNDERHt.skunder: suatu Ht dengan
penyebab yg dapat di identifikasikanPenyebab:1. peny. Ginjal;2.hiper
sekresi aldos- teron krn kelainan cortex adrenalis; 3.tumor kel medulla adrenalis (feokromositoma); 4.toxae- mia gravidarum; 5.grave`s disease?; 6.peny. Kardiovaskuler.
Gejala: Tek.drh > normal (S/D ) & jika D > 120 mmHg dikenal Ht. Maligna dng gejala se- perti papil edema, stroke,gagal jantung &ginjal.
PENYEBAB HYPERTENSION
HYPER-TENSION
Tu.med Adr
Tu cortex
ald
Renin-Agt
Retensi Na &H2O
KVS defect:
CNS
Cushing
COR
Head injury,tu-Mor,psychiatricdisturbances
Stenosis Ao
atherosclerosis
hipertiroidism
Ht renal
Spasme
Constr.renal
Hidronefrosis,pyelonefritis,GNA/C
Toxaemia,
KOMPLIKASI HIPERTENSI JANTUNG:
Ht. Menyebabkan beban kerja jantung & merusak pembuluh darah sehingga “TPR” meningkat.
Hipertropi ventrikel kiri left heart failure Ht. Meningkatkan faktor “after load” O2D > O2S SEHINGGA TERJADI INSUFISIENSI
KORONER OTAK:
Stroke ( transient cerebral ischemia attack/bleeding)
Hypertensive encephalopathy (gejala prodromalnya mual-muntah,insomnia, sulit konsentrasi, akhirnya coma & kejang2.
ARTERI: proses sklerosis, trombosis dan pembuluh drh mudah pecah (jantung,ginjal,otak dll).
140
130
115
90
155
N
Border line
95S
D
Area
Area
peningkatan
190
60
Area
Abnormal
VARIASI
BLOOD PRESSURE
OBAT ANTI HIPERTENSI TUJUAN: MENGEMBALIKAN “PERAN SISTIM
CONTROL Bp” AGAR DAPAT BERFUNGSI & MENGHINDARI KOMPLIKASINYA
OBAT : BETA BLOKERS: PROPANOLOL, ATENOLOL,
OXYPRENOLOL,NADOLOL,CARTEOLOL. DIURETIKA: HCT; FUROSEMIDE, DIAMOX.,
SPIRONOLACTON,ALDACTON,C.THALIDONE. VASODILATATOR: KALSIUM ANTAGONIST
MISALNYA: DILTIAZEM, NIFEDIPINE, VERAPAMIL, AMIODIPINE.
ANTICONVERTING ENZYM/ACE INHIBITORS: CAPTOPRIL ( CAPOTEN,CAPTENSIN)
GABA : HEXAMOTHONIUM. ANXIOLYTIC:MENCEGAH STIMULASI HIGHCENTER.