Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Make your likes visible on Facebook?

Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.

No, thanks

BLOOD PRESSURE 2014

No description
by

Nurulezah Hasbullah

on 5 February 2014

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of BLOOD PRESSURE 2014

BLOOD PRESSURE 2014
BLOOD PRESSURE
Definition:
Pressure exerted by circulating blood upon the walls of blood vessels
Usually refers to the arterial pressure of the systemic circulation
Varies between a maximum (systolic) and a minimum (diastolic) pressure
Decreases as the circulating blood moves away from the heart through arteries through heart pump & resistance of vessels
PULSE PRESSURE (PP)
Arterial pressure fluctuates with the pulsatile nature of cardiac output (CO)
It is determined by the interaction of stroke volume (SV), compliance of the aorta & resistance to flow
It can be simply calculated from the difference of the measured systolic and diastolic pressures


PP = SBP – DBP


Normal value is 40 mmHg

VARIATIONS IN BLOOD PRESSURE
can be divided into 2 classification; physiological and pathological
Arterial Blood Pressure
Systolic Blood Pressure (SBP) :
the peak pressure during the ventricular systole

Diastolic Blood Pressure (DBP) :
the minimum pressure during the ventricular diastole
SBP represents the
maximal
aortic pressure following ejection

As the left ventricle is relaxing and refilling, the pressure in the aorta falls

DBP represents the
lowest
pressure in the aorta, which occurs just before the ventricle ejects blood into the aorta
Normal SBP = 120 mmHg
Varies between 100-140 mmHg

Normal DBP = 80 mmHg
Ranges between 60-90 mmHg
Mean arterial pressure (MAP)
Average pressure that exists in the arteries

Can be approximately determined from measurements of the systolic pressure and the diastolic pressure while there is a normal resting heart rate
MAP = DBP + 1/3 (Pulse Pressure)

When BP is 120/80 mmHg, mean arterial pressure = 93 mmHg
Age
Sex
Body built
Diurnal variation
Postprandial
During sleeping
Emotional status
Post exercise
Physiological
Hypertension
Hypotension
Pathological
DETERMINANTS OF BLOOD PRESSURE
Can be divided into
Central
and
Peripheral
factors
Cardiac output (CO)
SBP depends on stroke volume (SV) and
cardiac output
When CO increases, SBP also increases and vice versa
CO depends on blood volume, venous return (VR), force of contraction

Heart rate (HR)
Moderate alteration in HR does not change the BP much but
greater alteration in HR, increases CO
Central factor
Peripheral factor
Peripheral resistance
It
maintains DBP
Directly proportional to DBP
When peripheral resistance decreases, DBP is less and vice versa
Blood volume
BP directly proportional to blood volume
Maintains through VR and CO
More blood volume, increases VR and CO
Venous return
Directly proportional to BP
When increase in VR, increase in ventricular filling & CO  rise in BP
Elasticity of blood vessels
Because of the
elastic properties
, vessels able to distend and maintain pressure
In arteriosclerosis, pressure increases
Velocity of blood flow
If velocity increases, the resistance also increases
leading to increase pressure
Diameter of blood vessels
BP is inversely proportional to diameter of vessels
The smaller the diameter, the resistance increases  increase BP


Viscosity of blood
When
blood viscosity increases, frictional resistance also increases
- increase BP
Example:
In polycythemia; increase viscosity of blood causes increase in BP
In anemia; viscosity is less, therefore pressure decreases
ARTERIAL BLOOD PRESSURE
It is determined by CO & total peripheral resistance (TPR)
BP = CO x TPR
CARDIAC OUTPUT
Volume of blood being pumped by the heart

Determined by stroke volume (SV) and heart rate (HR)


CO = SV x HR

Stroke Volume (SV) = amount of blood pumped out by each ventricle during each heart beat

Heart rate = number of heartbeats or beats per minute (bpm)
TOTAL PERIPHERAL RESISTANCE (TPR)
Sum of the resistance of all peripheral vasculature in the systemic circulation
TPR = P / Q
P is the change in pressure across the systemic circulation from its beginning to its end (pressure gradient)
Q is the flow through the vasculature (equal to CO)
Determined by:
Radius of blood vessel
Pressure gradient
Viscosity of blood
Changes in diameter of blood vessels
An increase in diameter during vasodilatation causes a reduction in TPR
A decrease in diameter during vasoconstriction causes a rise in TPR
Binding of Epinephrine and Norepinephrine to alpha-1-receptor on vascular smooth muscles leads to vasoconstriction. Therefore causes a reduction in the radius of the peripheral vessels that contributes to a rise in TPR

Volume of blood flowing depends on the viscosity of blood

Viscosity is the friction of blood against the vessels wall and it influences the blood flow through resistance

Pressure gradient is different in different areas of vascular bed
Total Peripheral Resistance
BLOOD PRESSURE REGULATION
There are 4 mechanisms involved to maintain blood pressure;
Nervous mechanism – short term
Renal mechanism – long term
Hormonal mechanism
Local mechanism
Nervous mechanism
Rapid – within few minutes

Operates for short period and adapts to new pressure

Short term regulation

Regulated by vasomotor centre and impulses from periphery (vasoconstrictor and vasodilator fibres)

Vasomotor centre – reticular formation of medulla oblongata and lower part of pons
Baroreceptor mechanism
Chemoreceptor mechanism
Renal mechanism
When blood pressure alters slowly within days/months/years, the nervous mechanism adapts to the altered pressure and looses its sensitivity

Long term regulation

Controlled by regulation of ECF volume and renin–angiotensin mechanism
Hormonal mechanism
Many hormones involved

Regulates BP by causing vasoconstriction and vasodilatation

Examples:
Increase BP: adrenaline, noradrenaline, angiotensin
Decrease BP: ANP, bradykinin
Local mechanism
Also regulates BP by local vasoconstriction and vasodilatation

Local vasoconstriction – endothelial origin, endothelins (ET1,ET2,ET3)

Local vasodilatation
Metabolic origin – CO2
Endothelial origin – nitric oxide (NO)

MEASUREMENT OF ARTERIAL BLOOD PRESSURE
2 methods
Apply more to animals and experimental studies

A cannula or T-tube is inserted into artery and connected to either
Mercury manometer
Pressure transducer
Direct Method
Apparatus used
Sphygmomanometer
Stethoscope

By two methods
Palpation method
Auscultation method
Indirect Method
Indirect measurement of Arterial BP
Manual BP reading using sphygmomanometer
Palpation
Auscultation

Digital BP reading using automated BP machine
Korotkoff Sounds
Sounds that are heard during auscultatory method in BP measurement
Caused by turbulent flow in an artery
During cuff inflation, artery is flattened
The artery changes its shape that eventually disrupts the blood flow through it causing turbulence
When liquid or fluid travels through a hollow tube and faces turbulence, it causes vibration that can be heard as sounds called Korotkoff sounds
Korotkoff phase 1
– appearance of sounds, snapping in nature: systolic blood pressure reading

Korotkoff phase 2
– sounds have murmur-like quality

Korotkoff phase 3
– sounds become clear and sharp

Korotkoff phase 4
– muffling of sounds

Korotkoff phase 5
– disappearance of sounds: diastolic blood pressure reading
www.merckmanuals.com
www.biology.creighton.edu
www.humanphysiology2011.wikispaces.com
www.stepbystep.com
www.topknowhow.com
Good luck!!!
Just have fun studying Blood Pressure...
don't pressure your brain...
Dr Ezah
Full transcript