1. Heart control
DR. HANA OMER

2. CONTROL OF CARDIAC OUTPUT
The control of cardiac output is essential for adjustments of the blood pressure and blood flow requirements under different physiological and pathological states .
Example :
1. muscular exercise increases the oxygen demand
2. in cases of fever, there is dilatation of the vascular bed with consequent lowering of arterial blood pressure .

3. Regulation of the heart rate
It is by neural or humoral mechanisms .
The neural mechanisms depend on autonomic innervation, and the humoral mechanisms depend on baro and chemoreceptors .

4. The Autonomic Nervous System and the Heart
Autonomic nervous system controls involuntary actions
Works with the voluntary nervous system to allow body functions to proceed smoothly

5. The Autonomic Nervous System and the Heart
Autonomic nervous system conductors:
Sympathetic nervous system
Speeds up the heart
Parasympathetic nervous system
Regulates the rate .

6. The Autonomic Nervous System and the Heart
Parasympathetic nervous system
it slow the heart rate .
Sends messages through vagus nerve, which can be stimulated by:
Pressure on carotid sinus
Straining against a closed glottis (Valsalva maneuver)

7. The Autonomic Nervous System and the Heart
Parasympathetic nervous system (cont’d)
If brain senses the heart should slow its pace:
Electrical impulse travels to the SA node
Causes release of acetylcholine (ACh)
Signals node to slow heart .

8. The Autonomic Nervous System and the Heart

9. The Autonomic Nervous System and the Heart
Sympathetic nervous system
Adapts to changing demands
Increases heart rate
Strengthens cardiac muscle contraction force
increase CO

10. The Autonomic Nervous System and the Heart
Sympathetic nervous system (cont’d)
In response to need for more oxygen:
Brain sends message through nerves to heart
Commands conveyed through release of norepinephrine and Epinephrine
Heart speeds up to prevent lactic acid buildup .

11. Drugs that Act on the Sympathetic Nervous System
Classified by the receptors with which they interact (alpha and beta receptors)

12. Drugs that Act on the Sympathetic Nervous System

13. Drugs that Act on the Sympathetic Nervous System
Sympathomimetic drugs imitate actions of naturally occurring sympathetic chemicals
Isoproterenol: pure beta agent

14. Drugs that Act on the Sympathetic Nervous System
Phenylephrine: pure alpha agent
Other drugs have varying degrees of alpha and beta activity.

15. Drugs that Act on the Sympathetic Nervous System
Beta-sympathetic agents classified as:
Beta-1 adrenergic agonists: work on cardiac beta receptors
Beta-2 adrenergic agonists: work on pulmonary beta receptors

16. Drugs that Act on the Sympathetic Nervous System
Sympatholytic blockers work by beating agents to receptor sites.

17. Drugs that Act on the Sympathetic Nervous System
Beta adrenergic blockers occupy beta receptors.

18. Drugs that Act on the Sympathetic Nervous System
Major autonomic agents:
Atropine: Parasympathetic blocker
Used to speed the heart
Norepinephrine: Sympathetic agent
Used to increase blood pressure
Isoproterenol: Sympathetic agent
Used to increase CO and dilate bronchi

19. Drugs that Act on the Sympathetic Nervous System
Major autonomic agents (cont’d):
Epinephrine: Sympathetic agent
Used for peripheral vasoconstrictor effect
Dopamine: Sympathetic agent
Used to increase renal perfusion, increase rate and force of myocardial contraction, and constrict peripheral blood vessels

20. Drugs that Act on the Sympathetic Nervous System
Major autonomic agents (cont’d):
Albuterol: Sympathetic beta-2 agent
Used to induce bronchodilation.
Propranolol: Sympathetic beta blocker
Used to slow the heart rate, decrease chronic angina pain, and to depress irritability in the heart