Regulation of blood pressure
-
Upload
ali-mansoor -
Category
Education
-
view
1.050 -
download
3
Transcript of Regulation of blood pressure
www.free-ppt -templates.com
www.free-ppt -templates.com
Presented To:
Ms. Komal Najam
Presented by:
Ali Mansoor
Abdullah Yaqoob
Harry Hamid
www.free-ppt -templates.com
Arterial Blood-Pressure
a. Definition
b. Regulation
Mechanisms of B.P Regulation
Nervous mechanism for B.P regulation
a. Baro-receceptor Mechanism
b. Chemoreceptor mechanism
Renal mechanism for B.P regulation
Hormonal Mechaism
Local Mechanism
Reflexes and Responses
Marey Reflex
Atrium-brainbridge Reflex
Bezold-Jarisch Reflex
www.free-ppt -templates.com
Definition:• Arterial blood pressure is defined as the lateral pressure exerted by the
column of blood on wall of arteries.• LOCAL FACTORS DETERMINIG THE ARTERIAL BLOOD
PRESSURE
www.free-ppt -templates.com
There are four mechanisms for regulation of the blood pressure.
1. Nervous mechanism or shortterm regulatory mechanism
2. Renal mechanism or longterm regulatory mechanism
3. Hormonal mechanism
4. Local mechanism.
www.free-ppt -templates.com
www.free-ppt -templates.com • Most rapid among all the mechanisms
• It operates through the vasomotor system.
Vasomotor SystemVasomotor system includes three components:
1. Vasomotor center (control heart rate)
2. Vasoconstrictor fibers (vasoconstriction)
3. Vasodilator fibers (vasodilation)
(Receives impulses from
Baroreceptors & Chemoreceptors.)
www.free-ppt -templates.com
www.free-ppt -templates.com
Rise in B.P activation of impulses to nucleus
baroreceptors of tractus solitarius
nucleus ofReduces vasomotor inhibition of tractus solitarius acts
. tone vasoconstrictor area on vasomotor center
excites vasodilator area
Redution in peripheral resistance Blood-
& Vasodilatation occur pressure
decreases(force of contraction &
Cardiac output decrease)
www.free-ppt -templates.com When blood pressure falls below
normalCarotid sinus and aortic arch
receptor potential
Rate of firing in afferent nervesCardiovascular center
Sympathetic cardiac nerve activity
and
sympathetic vasoconstrictor nerve activity
and
parasympathetic nerve activity
Heart rate
and
stroke volume
and
arteriolar and venous vasoconstriction
Cardiac output
and
total peripheral resistance
Blood pressure increased toward normal
www.free-ppt -templates.com
www.free-ppt -templates.com
Decreased blood pressure
Decreased flow of blood
Decrease in O2 & Increase in CO2
Excitation in the chemoreceptors
Send impulses to vasoconstrictors
Blood pressure rises and blood flow increases
www.free-ppt -templates.com
www.free-ppt -templates.com • Long term regulation of Arterial B.P
• Renal Mechanism works even whennerous mechanism adapts to the newpressure.
• Two ways of regulation of B.P
1. By regulation of ECF volume
2. Through reninangiotensin mechanism.
www.free-ppt -templates.com
Increase in excretion of water excretion of salts (sodium)
B.P (pressure diuresis) (Pressure Natriuresis)
Blood pressure decrease in blood decrease in ECF
restored volume volume
www.free-ppt -templates.com Decrease in reabsorption Increase in ECF
B.P from & Blood
renal-tubules volumes
Blood pressure Increase in cardiac
Restored output
www.free-ppt -templates.com
www.free-ppt -templates.com Renin along with Angiotensin forms Renin-
Angiotensin system, which is a hormone systemthat plays an important role in the maintenance ofblood pressure
Renin - J.G Cells of
Kidney
Angiotensinogen - Liver Cells
ACE - Lungs
www.free-ppt -templates.com
www.free-ppt -templates.com
www.free-ppt -templates.com
www.free-ppt -templates.com
www.free-ppt -templates.com • Local mechanism regulates blood pressure by
Vasoconstriction & vasodilatation.
Local vasoconstrictors• Are also called EDCF (endothelium derived constricting
factors) as they are derived from vascular endothelium.
• Common EDCF are ET1, ET2 & ET3.
• Produced by stretching of blood vessels & causevasoconstriction.
www.free-ppt -templates.com
Vasodilators of metabolic origin:
carbon monoxide, lactate, H+ & adenosine.
Vasodilators of Endothelial origin:
• Nitroxides
• NO3 (nitrate)
• NO+ (nitrosonium ion)
• NO- (nitroxyl anion)
www.free-ppt -templates.com • Vasomotor center regulates the cardiac activity by
receiving impulses from different sources in the body. After receiving the impulses from different sources, the vasodilator area alters the vagal tone and modulates the activities of the heart.
• Various sources from which the impulses reach the vasomotor center:
1. IMPULSES FROM BARORECEPTORS – MAREY REFLEX
2. IMPULSES FROM RIGHT ATRIUM – BAINBRIDGE REFLEX
3. BEZOLD-JARISCH REFLEX
www.free-ppt -templates.com • Baroreceptors regulate the heart rate through Marey reflex.
Stimulus for this reflex is increase in blood pressure.
• Marey reflex is a cardioinhibitory reflex that decreases heart rate when blood pressure increases.
• Whenever blood pressure increases, the aortic and carotid baroreceptor are stimulated.
• stimulatory impulses are sent to nucleus of tractus solitariusvia Hering nerve and aortic nerve.
• then nucleus of tractus solitarius stimulates vasodilator area and increase the vagal tone leading to decrease the heart rate
www.free-ppt -templates.com • Bainbridg reflex is a cardio accelerator reflex.
• Increases the heart rate when venous return is increased.
• This reflex rises from right atrium it right atrial reflex.
• Increase in venous return causes distention of right atrium and stimulation of stretch receptors, situated in the wall of right atrium.
• Stretch receptors, in turn, send nerve to vasodilator area of vasomotor center. Vasodilator area is inhibited, resulting in decrease in vagal tone and increase in heart rate.
www.free-ppt -templates.com
• This is also called coronary chemoreceptors.
• Bezold- Jarisch reflex is a pathological reflex and it does not occur in physiological conditions.
• Conditions when Bezold-Jarisch Reflex Occurs.
1. Myocardial infarction
2 .Administration of thrombolytic agents
3. Hemorrhage
4. Aortic stenosis
5. Syncope.
www.free-ppt -templates.com • Hypertension
• Hypotension
• Hypertention; when sistolic pressure remain elevated above 150 mm Hg and distolic pressure
remains 90 mm Hg is called hypetrtention.
• Hypotention;when the sistolic pressure less then 90 mm Hg is called hypotention.
www.free-ppt -templates.com
www.free-ppt -templates.com