Presentation is loading. Please wait.

Presentation is loading. Please wait.

CARDIOVASCULAR PHYSIOLOGY BLOOD PRESSURE AND ITS REGULATION.

Similar presentations


Presentation on theme: "CARDIOVASCULAR PHYSIOLOGY BLOOD PRESSURE AND ITS REGULATION."— Presentation transcript:

1

2

3 CARDIOVASCULAR PHYSIOLOGY BLOOD PRESSURE AND ITS REGULATION

4 Define blood pressure and Mean Arterial Pressure (MAP) List the factors affecting MAP Describe Short term and long term control of Blood Pressure OBJECTIVES At the end of this lecture you should be able to

5 BLOOD PRESSURE REGULATING MECHANISMS 1.Short Term (Nervous System works within few seconds) Baroreceptors Chemoreceptors CNS Ischemic Response 2.Long Term (Renal Control works within few days) 3.Intermediate (Within few hours) Stress relaxation Capillary fluid shift

6 1. Vasoconstrictor area 2. V asodilator area 3. S ensory area VASOMOTOR CENTER (Area!)

7 1. A vasoconstrictor area located bilaterally in upper medulla. excite vasoconstrictor neurons of the sympathetic nervous system. 2. A vasodilator area located bilaterally in the lower half of the medulla. inhibit the vasoconstrictor area, thus causing vasodilation. 3. A sensory area located bilaterally in medulla and pons (tractus solitarius). Receive sensory nerve signals from vagus and glossopharyngeal nerves and output control the vasoconstrictor and vasodilator areas An example is the baroreceptor reflex

8 Continuous Partial Constriction of the Blood Vessels Is Normally Caused by Sympathetic Vasoconstrictor Tone.

9 CONTROL OF VMC Reticular Substance of Brain Stem Hypothalamus Posterolateral portions Cause Excitation. Anterior part can cause Excitation or Inhibition Cerebral Cortex Motor Cortex Cause Excitation

10 Renal compensation Baroreceptor reflex Short-term Control Long-term control Control of blood pressure

11 Baroreceptors

12

13 Baroreceptor Reflex Quick operation (within few seconds) Influences heart & blood vessels Adjusts CO &TPR to restore BP to normal Mediated through autonomic nerves

14 Renal Control Slow operation (within hours to Days) Influences Kidneys & blood vessels Adjusts urinary output and TPR to restore BP to normal Mediated through Kidneys Renin Angiotensin aldosterone mechanism, It is perfect 100 %

15 Components Of Baroreceptor Reflex Arc Receptors Afferents Center Efferents Effectors Baroreceptors in carotid sinuses & arch of aorta Carotid sinus nerves & nerve from arch of aorta Vasomotor Center in medulla oblongata Sympathetic & parasympathetic nerves Heart and blood vessels Carotid sinus nerve runs along with glossopharyngeal nerve Aortic nerve runs along with vagus nerve

16 COMPONENTS OF BARORECEPTOR REFLEX ARC

17 Receptors Afferents Center Efferents Effectors Baroreceptors Increase Firing of Glossopharyngeal and Vagus Nerves Vasomotor Center in medulla oblongata  Sympathetic &  parasympathetic firing Heart and blood vessels Stimulus Effects Increase in BP  Heart rate and force of contraction and Vasodilatation  BP

18 Receptors Afferents Center Efferents Effectors Baroreceptors Minimal Firing of Glossopharyngeal and Vagus Nerves Vasomotor Center in medulla oblongata  Sympathetic &  parasympathetic firing Heart and blood vessels Stimulus Effects Decrease in BP Heart rate and force of contraction and Vasoconstriction  BP

19 Baroreceptor reflex  MAP  Firing of baroreceptors  Sympathetic tone  HR  Cardiac output  MAP  SV Vasodilatation  TPR  Vagal tone

20 What shall be the effect of bilateral cutting of the carotid sinus nerves? What shall be the effect of bilateral clamping of the carotid arteries proximal to the carotid sinuses? OR ? Can you guess ! Can you guess ! ? Rise in blood pressure and heart rate. Rise in blood pressure and heart rate. !! Because the inhibitory control of sympathetic is gone Because the inhibitory control of sympathetic is gone

21 Pressure on the carotid sinus, produced, for example by the tight collar or carotid massage marked bradycardia vasodilatation Fainting or syncope can cause

22 Transient loss of consciousness Syncope Associated with Abrupt vasodilatation Inadequate cerebral blood flow Hypotension and bradycardia

23

24 Pressure “ Buffer ” Function of the Baroreceptor Control System.

25 Pressure “ Buffer ” Function of the Baroreceptor Control System.

26 COTROL OF ARTERIAL PRESSURE IS ALSO BY Chemoreceptors (Carotid and Aortic Bodies) Atrial and Pulmonary Artery Reflexes (Low Pressure Receptors) CNS Ischemic Response

27

28 Pressure Natriuresis and Pressure Diuresis

29

30 Increased Fluid Volume Can Elevate Arterial Pressure by Increasing Cardiac Output or Total Peripheral Resistance

31 Salt (NaCl) intake & Arterial Pressure Regulation

32

33  MAP  Renin secretion  Angiotensin I Vasoconstriction  TPR Angiotensinogen  Angiotensin II Salt & water Retention  ECF Volume  MAP ACE in Lungs

34

35 ACE synthesize Ang II (Vascoconstrictor) and Inactivates Bradykinin (Vasodilator)

36  MAP  Urine formation  Blood volume  venous return  EDV  Stroke volume  Cardiac output  MAP

37

38

39

40 THANKS


Download ppt "CARDIOVASCULAR PHYSIOLOGY BLOOD PRESSURE AND ITS REGULATION."

Similar presentations


Ads by Google