The document defines arterial blood pressure and its components: systolic, diastolic, pulse, and mean arterial pressure. It discusses factors that regulate blood pressure, including the nervous system's vasomotor center and reflexes, the kidneys' regulation of fluid volume and renin-angiotensin system, and hormonal factors. It also covers hypertension and hypotension, defining each and describing primary vs. secondary causes, manifestations, and treatment approaches.

1. DR MUHAMMAD UMAR HABIB
LECTURER UNIVERSITY OF SARGODHA, LAHORE CAMPUS

3. Arterial Blood Pressure:
Definition:
• Defined as the lateral pressure exerted by the contained
column of blood on the wall of arteries
• It is expressed in four different terms
1. Systolic Pressure
2. Diastolic Blood Pressure
3. Pulse Pressure
4. Mean Arterial Pressure

4. Systolic Pressure
• Systolic Pressure is the maximum pressure
exerted in the arteries during systole of the
heart.
• Normal systolic pressure: 120 mm Hg (110 mm
Hg to 140 mm Hg)
Diastolic Blood Pressure
• Diastolic Blood Pressure is the minimum
pressure in the arteries during diastole of the
heart
• It varies between 60-80 mmHg

6. Pulse Pressure
• It is the difference between the systolic pressure
and diastolic pressure
• It is normally 40 mmHg
Mean Arterial Blood Pressure:
• It is the average pressure exist in the arteries
• It is the diastolic pressure plus one third of pulse
pressure
• = Diastolic + Pulse Pressure/3
• Normal mean arterial pressure: 93 mm Hg
(80 + 13 = 93).

7. Physiological Variations
Age (increases with age)
Sex (more in males)
Body Built (more in obese person)
Diurnal Variation (in evening low)
After meal (increases)
During sleep (decreases)
After exercise (increases)

8. Factors Maintaining Atrial Blood
Pressure
Central
factors
Peripheral
factors

9. Central Factors
Cardiac
output Heart rate

10. Peripheral factors
Peripheral resistance
Blood volume
Venous return
Elasticity of Blood
vessels
Velocity of blood flow
Diameter of blood
vessel
Viscosity of blood

11. Peripheral Resistance
• Peripheral resistance is the important factor, which
maintains diastolic pressure.
• Diastolic pressure is directly proportional to
peripheral resistance.
• Resistance is offered at arterioles, which are
called the resistant vessels.
• When peripheral resistance increases, diastolic
pressure is increased and when peripheral
resistance decreases, the diastolic
pressure is decreased.

12. Blood volume
• Blood pressure is directly proportional to blood
volume
• It maintain the blood pressure through venous
return and cardiac output
Venous Return:
• Blood pressure is directly proportional to venous
return
• When venous return is more, there is increase in
ventricular filling and cardiac output resulting in
elevation of arterial blood pressure

13. Elasticity of Blood Vessels
• Blood pressure is inversely proportional to
Elasticity of Blood Vessels
• Due to elasticity, the blood vessels are distensible
and are able to maintain the pressure otherwise
they become rigid and pressure increase in old
age.
Velocity of Blood Flow
• The Blood pressure is directly proportional to
the velocity of blood flow

14. Diameter of Blood Vessels
• Blood pressure is inversely proportional to
diameter of blood vessel
• If diameter decreases, the peripheral resistance
increases
• It increase the blood pressure
Viscosity of blood:
• Blood pressure is directly proportional to
Viscosity of blood
• More viscous the blood more will be the
resistance

15. REGULATION OF ARTERIAL
BLOOD PRESSURE

16. Regulation of Arterial Blood Pressure
• Body has four regulatory mechanisms to
maintain the blood pressure with in normal
limits
1. Nervous Mechanism or short-term
regulatory mechanism
2. Renal Mechanism or long term regulatory
mechanism
3. Hormonal mechanism
4. Local mechanism

18. Nervous Mechanism or short-term
regulatory mechanism
• Nervous regulation is rapid among all the
mechanisms involved in regulation of blood
pressure
• Although nervous mechanism is quick in
action, it operates only for a short period and
then it adapts to the new pressure.
• The nervous mechanism regulating the arterial
blood pressure constitutes the vasomotor
system

19. Vasomotor System
Vasomotor
center
Vasoconstrictor
fibers
Vasodilator
fibers

20. Vasomotor center
• Ii is situated in thee reticular formation of medulla
oblongata
• It has three parts:
1. Vasoconstrictor area
2. Vasodilator area
3. Sensory area

21. Vasoconstrictor area:
• It is also called the pressor area
• It sends impulses to blood vessels through
sympathetic Vasoconstrictor fibers
• This is concerned with acceleration of heart rate
Vasodilator area:
• It is also called depressor area
• This area suppresses the Vasoconstrictor area

24. Sensory area:
• It is the nucleus of the system
• It receives sensory impulses from peripheral
nerves
• It controls the Vasoconstrictor area and Vasodilator
area

25. Vasoconstrictor Fibers:
• The nerve fibers, which cause constriction of
the blood vessels
• They cause Vasoconstriction by the release
of neurotransmitter substances,
noradrenaline
• Vasoconstrictor fibers play major role than
the vasodilator fibers in the regulation of
blood pressure.

27. Vasodilator Fibers
• The nerve fibers which cause dilation of the
blood vessels
• These are of three types:
1. Parasympathetic Vasodilator Fibers
2. Sympathetic Vasodilator Fibers
3. Antidromic Vasodilator Fibers

28. • Parasympathetic Vasodilator Fibers
Parasympathetic vasodilator fibers cause
dilatation of blood vessels by releasing
acetylcholine.
• Sympathetic Vasodilator Fibers
Some of the sympathetic fibers cause
vasodilatation in certain areas, by secreting
acetylcholine. Such fibers are called
sympathetic vasodilator or sympathetic
cholinergic fbers.

29. • Sympathetic cholinergic fbers, which supply
the blood vessels of skeletal muscles, are
important in increasing the blood flow to
muscles by vasodilatation, during conditions
like exercise
• Antidromic Vasodilator Fibers

30. Mechanism of Action of Vasomotor In
the regulation of Blood Pressure
• The vasomotor center regulates the arterial
pressure
• Its action depends upon baroreceptors,
chemoreceptors, higher centers and respiratory
centers
Baroreceptor Mechanism:
• The Baroreceptors are the receptors which give
response to the change in blood pressure
Situation:
• They are situated in the carotid sinus and aorta
• They are supply by Hering’s nerve, which is a
branch of glossopharyngeal nerve

31. Function:
• Whenever the pressure increase, the
baroreceptors are stimulated and impulses are
sent to nucleus of tractus solitaries stimulates the
vasodilator area, which in turn increases the vagal
tone leading to decrease in heart rate
• This reflex is cardio-inhibitory reflex and it is
called Marey’s reflex
• When pressure is less, the baroreceptors do not
send impulses
• According to Marey’s law, the pulse rate is
inversely proportional to blood pressure

34. Chemoreceptor Mechanism:
• Chemoreceptors are those who give response to
change in chemical constituent of blood
Situation:
• These are situated in the carotid body and aortic
body adjacent to baroreceptors
Nerve Supply:
• These are supplied by Herring Nerve which is
branch of glossopharyngeal nerve
• The aortic baroreceptors are supplied by aortic
nerve

35. Functions:
• Whenever there is hypoxia, hypercapnea or
increased hydrogen ion concentration in the
blood, the chemoreceptors sent inhibitory
impulses to vasodilator area
• They maintain the respiration mainly then the
heart rate

36. Higher Center:
• The vasomotor is also controlled by the impulses
from the two higher centers in the brain
1. Cerebral Cortex
2. Hypothalamus
Cerebral Cortex:
• Area 13 in cerebral cortex is concerned with
emotional reactions
• During emotional conditions this area sends
impulses to the vasomotor center which cause
increase in blood pressure

37. Hypothalamus:
• Stimulation of anterior hypothalamus causes
vasodilatation and decrease in pressure
Respiratory Centers:
• During beginning of breathing the arterial
pressure increases slightly
• And it decreases during later part of expiration

38. RENAL MECHANISM FOR
REGULATION OF BLOOD
PRESSURE

39. Renal Mechanism for Regulation of
Blood Pressure
• Kidney plays an important role in the long term
regulation of arterial blood pressure
• Kidney regulates arterial blood pressure by two
ways
• By regulation of Extra Cellular Fluid volume
• Through Renin-Angiotensin Mechanism

40. By regulation of Extra Cellular Fluid
(ECF) volume:
• When the pressure increases, kidney excrete
more amount of water and salt
• It reduces ECF volume and blood volume, which
in turn brings the arterial blood pressure back to
normal level
• When blood pressure decreases, the
reabsorption of water from renal tubules is
increased
• This is in turn increases ECF volume, blood
volume and cardiac output

41. Through Renin-Angiotensin
Mechanism
Action of Angiotensin II:
• When blood pressure and ECF volume decrease,
rennin secretion from kidney is increased
• It converts Angiotensinogen into Angiotensin I
• This is converted into Angiotensin II by
Angiotensin converting Enzyme

42. Action of Angiotensin II:
• Angiotensin II helps to restore the blood pressure
by 2 ways
• It causes constriction of arterioles in the body so
that the peripheral resistance is increased and
blood pressure rises
• Angiotensin II stimulates the adrenal cortex to
secrete aldosterone.
• This hormone increases reabsorption of sodium
from renal tubules, which is followed by
reabsorption of water resulting in increased ECF
volume and blood volume
• It increases the blood pressure to normal level

45. Hormonal Mechanism
for Regulation of Blood
pressure

46. Hormones which increase the blood
pressure
Adrenaline
Noradrenaline
Thyroxin
AldosteroneVasopressin
Angiotensin
Serotonin

47. Hormones which decreases the blood
pressure
Vasoactive intestinal
polypeptide (VIP)
Bradykinin
Prostaglandin
HistamineAcetylcholine
Arterial Natriuretic
peptide
Brain Natriuretic
peptide

48. Adrenaline:
• It increases systolic pressure, by increasing the
force of contraction of heart and cardiac output
• It decreases diastolic pressure by reducing the
total peripheral resistance
• It causes constriction of blood vessels

49. Noradrenaline:
• It increases diastolic pressure due to its general
vasoconstrictor effect
• It has strong effect on blood vessels than on the
heart
• It causes constriction of blood vessels via alpha
receptor
• It also increases the systolic pressure slightly

50. Thyroxin:
• It increases the systolic pressure but decreases
the diastolic pressure
• It increases systolic pressure, by increasing the
force of contraction of heart and cardiac output
• Due to production of different metabolites
vasodilation occurs
• Due to which peripheral resistance educed and it
decreases the diastolic pressure

51. Aldosterone:
• It causes retention of sodium and water and
there by increases the ECF fluid volume and
blood volume leading to increase in blood
pressure
Vasopressin:
• It has a potent action on the blood vessels
• It causes constriction of the arteries in all parts of
body
• Due to vasoconstriction, the blood pressure is
increased
• However large amount of hormone is required

53. Angiotensins:
• Angiotensin II, III and IV cause constriction of
systemic arterioles and elevates the blood
pressure
Serotonin:
• It is secreted in hypothalamus, limbic system,
cerebellum, spinal cord, retina and GI tract
• It causes vasoconstriction of blood vessels

55. Hormones which decreases the blood
pressure
Vasoactive intestinal polypeptide (VIP):
• It is secreted in stomach and small intestine
• It is a vasodilator and help in decreasing blood
pressure
Bradykinin:
• It is produced in blood during the condition like
inflammation
• In such conditions an enzyme kallikrein is activated
which is later on converted into Bradykinin
• It is a vasodilator and help in decreasing blood
pressure

56. Prostaglandins:
• It is secreted from all tissues of the body
• It is a vasodilator and help in decreasing blood
pressure
Histamine:
• It is secreted in nerve endings of the hypothalamus
and cerebral cortex
• It also causes vasodilation of blood vessels
Acetylcholine:
• It is a cholinergic neurotransmitter
• It is released by the precholinergic nerve endings of
sympathetic and parasympathetic divisions

57. Atrial Natriuretic Peptide (ANP):
• It is a hormone secreted by the atrial
musculature of heart
• It causes dilation of blood vessels and decreases
the blood pressure
Brain Natriuretic Peptide:
• It is a hormone secreted by the atrial
musculature of ANP
• It causes dilation of blood vessels and decreases
the blood pressure

58. LOCAL MECHANISM FOR
REGULATION
OF BLOOD PRESSURE

59. • The local substances regulate the blood
pressure by vasoconstriction or vasodilatation
• LOCAL VASOCONSTRICTORS
Local vasoconstrictor substances are derived
from vascular endothelium. These
substances are called endothelium-derived
constricting factors (EDCF)
Substances cause constriction of blood
vessels and increase the blood pressure.

60. • LOCAL VASODILATORS
Vasodilators of metabolic origin
Vasodilators of endothelial origin

61. APPLIED PHYSIOLOGY

62. HYPERTENSION
• Hypertension is defined as the persistent high
blood pressure.
• When the systolic pressure remain elevated
above 150 mm Hg and diastolic pressure
remains elevated above 90 mm Hg, it is
considered as hypertension.
• If there is increase only in systolic pressure, it
is called systolic hypertension

63. Types of Hypertension
Primary
hypertension
or essential
hypertension
Secondary
hypertension

64. Primary Hypertension or
Essential Hypertension
• Primary hypertension is the elevated blood
pressure in the absence of any underlying
disease.
• Primary hypertension is of two types:
i. Benign hypertension
ii. Malignant hypertension

65. i. Benign hypertension
• Benign hypertension is the high blood
pressure that does not cause any problem
ii. Malignant hypertension
• Malignant hypertension is a severe form of
hypertension with a rapid course leading to
progressive cardiac and renal diseases. It is
also called accelerated hypertension

66. Secondary Hypertension
• Secondary hypertension is the high blood
pressure due to some underlying disorders.
• The different forms of secondary
hypertension are:
• Cardiovascular hypertension
• Endocrine hypertension
• Renal hypertension
• Neurogenic hypertension
• Hypertension during pregnancy

67. Manifestations of Hypertension
• Severe manifestations of primary
hypertension:
1. Renal failure
2. Left ventricular failure
3. Myocardial infarction
4. Cerebral hemorrhage
5. Retinal hemorrhage.

68. Treatment of Hypertension
• Beta adrenoceptor blockers
• Alpha adrenoceptor blockers
• Calcium channel blockers
• Vasodilators
• Diuretics

69. HYPOTENSION
• Hypotension is the low blood pressure. When
the systolic pressure is less than 90 mm Hg, it
is considered as hypotension.
Types
• 1. Primary hypotension
2. Secondary hypotension.

70. Primary hypotension
• Primary hypotension is the low blood
pressure that develops in the absence of any
underlying disease and develops due to
some unknown cause. It is also called
essential hypotension.
Secondary hypotension
• Secondary hypotension is the hypotension
that occurs due to some underlying diseases.
Diseases, which cause hypotension are:
i. Myocardial infarction
ii. Hypoactivity of pituitary gland
iii. Hypoactivity of adrenal glands

71. Orthostatic hypotension
• Orthostatic hypotension is the sudden fall in
blood pressure while standing for some time.
• It is due to the effect of gravity. It develops in
persons affected by myasthenia gravis or
some nervous disorders like
tabes dorsalis, syringomyelia and diabetic
neuropathy.
• Common symptom of this condition is
orthostatic syncope.