1. Cardiovascular control mechanism
黃基礎

2. Introduction
Control of blood volume and arterial pressure results in that all of the organs receive sufficient blood flow.

3. Central controller Sensor Effector Sympathetic nerve Sensory nerve
Parasympathetic n
Sensory nerve
Sensor
Effector
Changes in BP
Heart and arteriole

4. Circulatory control system

5. Sensors
The animal body employs a variety of receptors for monitoring the status of the cardiovascular system.
There are two main baroreceptors aortic baroreceptor via vagus nerve carotid baroreptor via sinus nerve

7. An increase in blood pressure stretches
the wall of the carotid sinus, causing an
increase in discharge frequency from the
baroreceptors.

9. Chemoreceptors + Increase in CO2 Chemorecpeotr vasoconstriction
A rise in arterial pressure

10. Cardiac receptors Atrial receptors Increase in atrail filling
Increase in BP
Increase in
venous pressure
Stimulate the
atrial receptors
Reduction in
blood volume
Inhibition of
ADH release
Leasd to diuresis

11. Cardiac receptors Atrial receptors Increase in atrail filling
Increase in BP
Increase in
venous pressure
Strtch
the the atrial wall
Cause an increase
In urine production
and sodium
excretuib
Reduction in
blood volume
Cause atial myocytes
to secrete ANP

12. ANP Renin ADH Reduce Reduce release release Cardiac BP Output_
Renin
release
ADH
release
Reduce
Cardiac
Output
Reduce BP
Antagonize the
pressor effect of
angiotensin

13. Central nervous system
Medullaray CV center Pressor and depressor center Cardioaccerator center Cardioinhibitory center

14. Central nervous system
Autonomic nervous system (ANS) Sympathetic preganglionic fibers arise from cell bodies in the IML of the spinal cord of the thoracodorsal regions

15. Autonomic nervous system (ANS) 2
Autonomic nervous system (ANS) 2. The stellate ganglion supplies postganglionic sympathetic fibers to the heart All of preganglionic sympathetic fibers are cholinergic but the postganglionic sympathetic fibers are adrenergic or cholinergic

16. Parasympathetic nervous system
1. The primary effect of the
parasym. n. s. on CV function
is to slow the heart rate.
2. Impulses conducted by the
vagus nerve affect the S-A node,
A-V node and reduce artial
contractivitility

19. Neural pathways for thr BP control

20. NTS: nucleus tractus of the solitarius

22. Medullary cardiovascular center

23. Control of microcirculation
Capillary blood flow has to be adjusted to meet the demands of the tissue.
Two control mechanisms Neural control Local control

24. Neural control of capillary blood flow
Sympathetic stimulation and catcholamine
Stimulation of
alpha receptors
vasodilatation
Stimulation of
beta receptors
vasoconstriction
Vasoconstriction activated by  -adrenergic receptors would override vasodilatation by  -adrenergic receptors

25. Neuropeptide Y co-localized with norepinephrine within sympathetic ganglion and adrenergic nerve nerve endings that surrounded the atrial and ventricular myocytes and the coronary arteries contain neuropeptide Y NPY decrease coronary blood flow and the contraction of cardiac muscle by reducing the level of IP3
Parasympathetic stimulation cause to vasodilation in arterioles

26. Local control of capillary blood flow
Endothelium-produced compounds endothelium can produce NO, endothelin, and prostacyclin to affect the activity of the smooth muscle and hence, to regulate the capillary blood flow
Endothelium-derived
relacing factor
(now known NO)
cGMP
Muscle
relaxation

28. Local control of capillary blood flow
Endothelin can produce vasoconstriction prostacyclin can initiate vasodilation and act as an anticoagulant. Prostacyclin functions as an antagonist of the thromboxane A2 ,which promotes blood clotting and causes vasoconstriction Influammators and other mediators thromboxane A2 cause vasoconstriction histamine and kinin produce vasodilatation

29. Histamine, bradykinin, and serotonin cause an increase in capillary permeability
Metabolic condition associated with activity decrease in O2, increase in CO2, and H+, a variety of metabolites (adenosine) , heart, rise in extracellular K+ , NO, prostacyclin all of the above substances produce vasodilation and a local increase in capillary blood flow.