Transcript Introduction to Blood Pressure - squ

Introduction to Blood
Pressure
Objectives





Define the term blood pressure.
Define the terms: systolic blood pressure,
diastolic blood pressure, mean arterial blood
pressure and pulse pressure.
Define the term total peripheral resistance
List the short, intermediate and long term
mechanisms involve on blood pressure
regulation
Describe the role of baroreceptors on blood
pressure regulation
Blood Pressure:
Generated by Ventricular Contraction
Arterial Blood Pressure (ABP)
Arterial Blood Pressure (ABP) is defined as the lateral
pressure exerted by the blood on the arterial walls.
Arterial blood pressure clinically
Systolic/Diastolic blood pressure
120/80 mmHg
expressed
as
Systolic Blood Pressure (SBP) is the maximal pressure
exerted by the blood on the arterial walls during ventricular
systole (100-140 mmHg).
Diastolic Blood Pressure (DBP) is the minimal pressure
exerted by the blood on the arterial walls during ventricular
diastole (60-90 mmHg).
Pulse Pressure (PP)
is the difference between systolic and diastolic pressures
e.g. 120 – 80 = 40 mm Hg.
Mean Arterial Blood Pressure (MABP)
is the average blood pressure in the arteries through out
the cardiac cycle. It is calculated:
MABP = DBP + 1/3 PP mm Hg.
MABP = 80+1/3 40 = 93.3 mm Hg.
Pulse and Mean Arterial Pressures
Physiological variation of ABP

Age

Sex

Body build

Exercise

Emotions

Sleep
Control of blood pressure





Mean arterial pressure is the main driving force
for propelling blood to tissues
MAP must be closely regulated
MAP Low
MAP high
Driving force for blood
flow unable to overcome
gravity
Weakening of arterial walls lead
to Aneurysms  Risk of rupture
& hemorrhage
O2 supply to brain 
Symptoms?
Cerebral hemorrhage
Rupture of major artery
Factors controlling mean arterial BP
MABP = CO x TPR
CO Cardiac Output (SVXHR)
TPR Total Peripheral Resistance (is the sum of the resistance of all
peripheral vasculature in the systemic circulation)
Regulation of Blood pressure

Short-term regulation





Acts with in seconds
Neural regulation (Baroreceptor reflexes >>> sympathetic and
parasympathetic)
Hormones (adrenal medulla epinephrine and norepinephrine)
Long-term regulation
Acts within minutes to days
(Kidney, rennin- angiotensin- aldosterone system)
Cardiovascular Center
Neural regulation of BP
1.Barorecptors reflexes
Baroreceptor
reflexes
2.Chemoreceptor Reflexes


Carotid & aortic body
Sensory receptors (detect blood levels of O2,
CO2, & H ions)
Hormonal Regulation Of BP
1. Adrenalin (Epinephrine) and nor-adrenaline (norepinephrine)
Sympathetic stimulation.

Adrenal medulla releases E + NE

Vasoconstriction of
arterioles & venules
HR  strength of contraction

CO
Increase BP
2. Reninangiotensinaldosterone (RAA)
system
3.Anti-diuretic hormone (ADH)
Synthesized in the hypothalamus and stored in the
posterior pituitary gland
* Dehydration or Blood Volume release of ADH 
kidneys  reabsorption of H2O Blood volume
BP
* In large amounts ADH vasoconstriction (vasopressin)
4.Atrial natriuretic peptide (ANP)
* Secreted by the atria of the heart
* Blood volume stretch cells in the atria of
the heart


Vasodilatation of
Blood vessels
Promote loss of Na & H2O
 Blood volume

BP
Homeostatic response to shock