1. 2
Cardiovascular Physiology: Function

2. Cardiovascular Physiology
Objectives
Describe the sequence of blood flow through the heart
Describe the cardiac cycle, including
Definition
Systole
Diastole

3. Cardiovascular Physiology
Objectives (continued)
Discuss the term stroke volume
Discuss cardiac output, preload, Starling’s law, and afterload
Describe the autonomic nervous system

4. Blood Flow Through The Heart
First component: blood flow through right heart:
Unoxygenated blood flows from inferior and superior vena cava, into the right atrium, through the tricuspid valve, into the right ventricle, and through the pulmonic valve

5. Blood Flow Through The Heart
Second component: blood flow through the pulmonary circulation continues when
The blood travels from pulmonary arteries, into the lungs, through the pulmonary alveolar-capillary network, and into the pulmonary veins

6. Blood Flow Through The Heart
The third and final component: blood flow through the pulmonary circulation continues when:
Blood travels from the pulmonary veins into the left atrium, through the mitral valve, into the left ventricle, through the aortic valve, and out to the rest of the body (coronary arteries first)

7. Cardiac Cycle Cardiac cycle Systole
Represents the actual time sequence between ventricular contraction and ventricular relaxation
Systole
Simultaneous contraction of the ventricles

8. Cardiac Cycle Diastole Synonymous with ventricular relaxation
Ventricles fill with 70% of blood passively from atria
Atriums add the last 30% upon contraction
Atrial kick

9. Cardiac Cycle
During periods of ventricular relaxation, cardiac filling and coronary perfusion occur passively
One cardiac cycle = every 0.8 seconds
Systole lasts = about 0.2 seconds
Diastole lasts = about 0.52 seconds

10. Cardiac Cycle

11. Relation of Blood Flow to Cardiac Contraction

12. Stroke Volume Stroke volume Heart rate
Volume of blood pumped out of one ventricle of the heart in single beat or contraction
Estimated at approximately 70 ml per beat
Heart rate
Number of contractions/beats per minute
Normal heart rate
bpm

13. Stroke volume (SV) X heart rate (HR)
Cardiac Output
Cardiac output
Amount of blood pumped by left ventricle in 1 min
FORMULA to determine cardiac output
Cardiac output (CO) =
Stroke volume (SV) X heart rate (HR)

14. Cardiac Output Cardiac output Varies from person to person
What effects Cardiac Output
Stoke Volume, PVR, Heart Rate
Inadequate cardiac output may be caused by
CHF, MI, or shock

15. Cardiac Output Decreased Cardiac output
May see combinations of symptoms:
Shortness of breath
Dizziness
Chest pain
Decreased blood pressure
Cool and clammy skin

16. End-Diastolic Pressure
Preload
Pressure in the ventricles at the end of diastole
Directly affected by volume of blood that returns to right atrium
May be decreased or increased based on returning volume
What can effect preload?
At the end of relaxation (just before contraction) is the diastole pressure of blood pressure which is the pressure in the vena cava…or the pressure of blood entering the heart……..and if pressure is too there will be no blood entering the atrium and thus none in left ventricle for contraction…
After load is the pressure in the arteries just before contraction, the amount of pressure the aortic valve has to over come for blood flow..

17. Affects stroke volume and cardiac output
Afterload
Resistance against which the heart must pump
Affects stroke volume and cardiac output

18. Starling’s Law of the Heart
This concept is a law of physiology which states that the more the myocardial fibers are stretched, up to a certain point, the more forceful the subsequent contraction will be
“Rubber band theory”
The farther you stretch a rubber band, the harder it snaps back to original size

19. Peripheral Vascular Resistance (PVR)
Amount of opposition to blood flow offered by arterioles
Determined by vasoconstriction and vasodilation
Blood pressure (BP) =
Cardiac output (CO) x peripheral
vascular resistance (PVR)

20. Autonomic Nervous System
Regulates functions of the body that are involuntary or are not under conscious control
HEART RATE and BLOOD PRESSURE are regulated by this component of nervous system
Where is this center located?

21. Two Major Divisions of Autonomic Nervous System
Sympathetic nervous system
Preparation of body for physical activity (“fight or flight”)
Parasympathetic nervous system
Regulates the calmer (“rest and digest”) functions of our existence
Feed or breed

22. Nervous Control of the Heart

23. Receptors and Neurotransmitters
Sympathetic nervous system
Receptors are
alpha- and beta-receptors
Chemical neurotransmitter is
norepinephrine
These nerve endings are called adrenergic
Increases the heart rate and contractile forces of cardiac muscle and vasoconstriction

24. Receptors and Neurotransmitters
Parasympathetic nervous system
Chemical neurotransmitter is
acetylcholine
Nerve endings are known as
Cholinergic
With a neurotransmitter of
Acetylcholine
Which causes what to happen?
The heart rate slows, as do atrioventricular conduction rates

25. Adrenergic Receptors and Their Effect on Heart Rate
Sympathetic nerve fibers that use epinephrine or epinephrine-like substances as neurotransmitters
Receptor
A reactive site or cell surface or within that combines with molecule to produce physiological effect

26. Adrenergic Receptors and Their Effect on Heart Rate
Cholinergic
Parasympathetic nerve fibers that use acetylcholine as neurotransmitter

27. Effects of Alpha/Beta Receptors

28. Effects of Alpha/Beta Receptors

29. How drugs effect the heart
Inotropic
Strength of contractions
Chronotropic
Heart Rate
Dromotropic
Velocity of conduction

30. Summary What did you learn?
You direct the summary….everyone tell me something DIFFERENT!!