Regional circulation

1. Regional Circulation
Dr. Sara Sadiq
(MBBS, M.Phil)
Assistant Professor
Department of Physiology

2. Areas of Study
• Coronary Circulation
• Cerebral Circulation
• Splanchnic Circulation
• Skeletal muscles Circulation
• Cutaneous Circulation

4. Why Coronary circulation is important ????
• Coronary artery disease is the leading cause of deaths
across the globe
• In USA 15.5 million people over the age of 20 suffer from
CAD
• One death every 42 seconds in USA

5. Physiological anatomy

6. Physiological anatomy
• Coronary arteries lie on the surface of heart
• Left Coronary artery (Left ventricle)
• Right Coronary artery (Right ventricle & part of left ventricle)
• Venous drains into Rt Atrium through Coronary Sinus (75%)
• Anterior Cardiac Vein

7. Anastomosis

8. Coronary blood flow
• 4-5% of Cardiac output
• 70 ml/min/100g of heart weight
• 225 ml/min
• 4-7 times increase during exercise

9. Phasic changes in coronary blood flow

10. Epicardial vS endocardial blood flow

11. Control of coronary blood flow
• Local muscle metabolism is the primary controller of coronary blood
flow
• Oxygen demand  A major regulator of coronary blood flow
• 70% oxygen extraction
• Role of Adenosine, ADP, AMP, K, H, CO2, Prostaglandins, NO

12. Nervous regulation
• Through autonomic nerves
• Direct & Indirect effects are opposite
• Direct effects of Vagal Stimulation (less extensive):
• Vasodilataion
• Direct effects of Sympathetic stimulation:
• Through alpha (constrictor) & Beta (Dilator) receptors

15. Factors Affecting Coronary Blood Flow
• Muscular exercise
• Emotional excitement
• Hypotension
• Hormones
• Heart rate
• Effect of ions
• Metabolic factors.

32. CEREBRAL Circulation
• 2 systems of Arteries
• Carotid System
• Vertebral System
• Combine to form Circle of Willis
• But still the collateral blood
supply is poor

34. CEREBRAL CIRCULATION

35. CEREBRAL VENOUS DRAINAGE
• Cerebral veins
• Dural venous sinuses
• Jugular System of Veins

36. CEREBRAL BLOOD FLOW
Normal Rate of Cerebral Blood Flow
• Normal blood flow through the brain of the adult person averages
50 to 65 milliliters per 100 grams of brain tissue per minute.
• For the entire brain, this amounts to 750 to 900 ml/min, or 15 per
cent of the resting cardiac output.

37.  Increase Cerebral Blood Flow in Response to Excess Carbon Dioxide or
Excess Hydrogen Ion Concentration.
 An increase in carbon dioxide concentration in the arterial blood
perfusing the brain greatly
 70 % increase in arterial PCO2 approximately doubles the cerebral
blood flow.
REGULATION OF CEREBRAL BLOOD FLOW

38. 1. Autoregulation of Cerebral Blood Flow When the Arterial
Pressure Changes.
Cerebral blood flow is “autoregulated” extremely well between
arterial pressure limits of 60 and 140 mm Hg.
REGULATION OF CEREBRAL BLOOD FLOW

39. •Mechanisms:
a) Myogenic
response
Smooth ms
respond to stretch
by contraction
b) Metabolic
response
Local changes in
brain metabolites

41. Factors disturb the autoregulation
• Hypoxia due to occlusive cerebrovascular disease
• Trauma from head injury or surgery
• Brain compression from tumors
• Hematomas or cerebral edema

42. 2. Role of the Sympathetic Nervous System in Controlling Cerebral
Blood Flow.
The cerebral circulatory system has strong sympathetic innervation
that passes upward from the superior cervical sympathetic ganglia in
the neck and then into the brain along with the cerebral arteries.
REGULATION OF CEREBRAL BLOOD FLOW

43. METABOLISM OF BRAIN
• 20% of total body O2 consumption
• Mostly Glucose…without Insulin
• Less during sleep

44. REGULATION OF CEREBRAL CIRCULATION
• FACTORS INVOLVED
• Vasomotor Nerves
• Autoregulation
• Metabolic activity
• Viscosity of Blood
• Intracranial pressure

45. 1. Fainting
2. Hypoglycemia
3. Stroke  blood supply to a part of the brain is blocked resulting in
the death of an area within the brain.
4. Transient ischaemic attack  When blood supply to a part of the
brain is temporarily interrupted without producing permanent
damage.
Clinical Implication

47. Splanchnic Circulation

48. SPLANCHNIC CIRCULATION
• ARTERIAL SUPPLY
• COELIAC AXIS
• SUPERIOR MESENTERIC
• INFERIOR MESENTERIC ARTERY
• VENOUS DRAINAGE
• INFERIOR MESENTERIC VEIN
• SPLENIC VEIN
• SUPERIOR MESENTERIC VEIN
PORTAL VEIN

49. DISTIBUTION OF BLOOD
• About 30% of cardiac out-put to Gut & Liver
• 2/3rd of Liver blood is from Portal Vein
• 1/3rd is from Hepatic Artery (Br of Coeliac Artery)
• Liver drains into Inf Vena Cava through Hepatic Veins

51. NERVOUS CONTROL
• MAINLY VASOCONSTRICTOR
• NO KNOWN VASODILATOR NERVE SUPPLY (MOSTLY
LOCAL FACTORS)

53. Circulation In Skeletal Muscle

55. REGULATION OF MUSCLE BLOOD FLOW
Neural Control:
• Sympathetic nervous system  vasoconstrictor
• An increase in sympathetic nervous system activity can decrease
flow by 70%
• Vasodilatation at rest is passive due to withdrawal of sympathetic
nervous system activity

56. REGULATION OF MUSCLE BLOOD FLOW
Metabolic Factors:
• With increased activity  increase in the production of
vasodilator metabolites
• Vasodilator metabolites are dominant during exercise although
sympathetic nervous system activity to the working muscle is
also enhanced

59. THE CUTANEOUS CIRCULATION
• BLOOD FLOW 1 - 100ml/100gm/min
• ANASTOMOTIC AREAS FOR HEAT REGULATION
• FINGERS
• TOES
• PALMS
• EAR LOBES

61. PROPERTIES OF SKIN CIRCULATION
• HEAT REGULATION
• RESERVOIR OF BLOOD
• TRIPLE RESPONSE
• RED REACTION
• WHEAL
• FLARE

62. THE TRIPLE RESPONSE
• RED REACTION
• CAPILLARY DILATATION
• WHEAL
• CAPILLARY LEAK
• HISTAMINE LIKE SUBSTANCE & SUBSTANCE-P
• FLARE
• ARTERIOLAR DILATATION

64. Fetal Circulation

67. Closure of the Foramen Ovale
• Flow backward through the foramen ovale •low right atrial pressure
• the high left atrial pressure
• Small valve that lies over the foramen ovale on the left side of the atrial
septum closes
• In two thirds of all people  the valve becomes adherent over the foramen ovale
within a few months to a few years and forms a permanent closure.

73. Circulation
• Blood Volume  300 milliliters
if the infant is left attached to the placenta for a few minutes after birth or if
the umbilical cord is stripped to force blood out of its vessels into the baby, an
additional 75 milliliters of blood enters the infant, to make a total of 375
milliliters.
• Cardiac Output  500 ml/min
• Arterial Pressure  70 mm Hg systolic – 50 mm Hg diastolic
 90/60 mm Hg - increases during the next several months
 115/70 mm Hg

75. Thank You