1. D. Cardiac Cycle: Mechanical Events
*Systole =
*Diastole =
*BP =
Atrioventricular valves
Open
Closed
Open
Aortic and pulmonary valves
Closed
Open
Closed
Phase 1 2a 2b 3 1
Left atrium
Right
atrium
Left
ventricle
Right
ventricle
Ventricular
filling
Atrial
contraction
Isovolumetric
contraction
phase
Ventricular
ejection
phase
Isovolumetric
relaxation
Ventricular
filling 1 2a 2b 3
Ventricular filling
(mid-to-late diastole)
Ventricular systole
(atria in diastole)
Early diastole

2. Cardiac Cycle … 1. Ventricular Filling: Mid-Late Diastole. a
Cardiac Cycle … 1. Ventricular Filling: Mid-Late Diastole a. Ventricles are Relaxed & Atria are Relaxed *Tricuspid & Bicuspid Valves are: open or closed? *Pressure is: In ventricle is high or low? b. Ventricles are Relaxed & Atria Contract *Why do the Atria contract?
Atrial contraction
Ventricular filling
Left atrium
Right atrium
Left ventricle
Right ventricle
Figure 11.7, step 1a

3. a. When Ventricles first begin to Contract:
Cardiac Cycle … 2. Ventricular Systole (Atrial are in Diastole)
a. When Ventricles first begin to Contract:
- *Isovolumetric Contraction = ?
- *Pressure: High or Low :
- *End Diastolic Volume =
b. *Ejection Phase: What occurs & what valves are open?
- *Pressure in Aorta is ?
Isovolumetric
contraction
phase
Ventricular
ejection
phase 2a 2b

4. (mid-to-late diastole)
Cardiac Cycle …
3. Early Diastole
*Isovolumetric Relaxation: describe
- *End Systolic Volume = describe
*Ventricular filling
- *Valves: Which are open?
Atrioventricular valves
Open
Closed
Open
Aortic and pulmonary valves
Closed
Open
Closed
Phase 1 2a 2b 3 1
Left atrium
Right
atrium
Left
ventricle
Right
ventricle
Ventricular
filling
Atrial
contraction
Isovolumetric
contraction
phase
Ventricular
ejection
phase
Isovolumetric
relaxation
Ventricular
filling 1 2a 2b 3
Ventricular filling
(mid-to-late diastole)
Ventricular systole
(atria in diastole)
Early diastole

5. *Homeostasis– Students Do:
Cardiac Cycle …
*Homeostasis– Students Do:
Tachycardia
Bradycardia
Figure 11.7, step 3

6. E. Control of Heart Function– Cardiac Output Is Controled by Stroke Volume & Heart Rate
1. Definition of Terms
*CO = Volume of blood pumped: finish definition
*Stroke Volume (SV) = Volume of blood: finish definition
- The two ventricles eject the same volume
*Heart Rate =
CO = heart rate (HR) x stroke volume (SV) = 5.25 L/min
*Cardiac Reserve = CO maximum – CO at rest

7. E. Control of Heart Function …
2. Regulation of Stroke Volume to control CO
- Stroke Volume Regulation is the most important factor for CO in healthy people
SV = EDV – ESV (intrinsic factor)
b. Preload: the amount of stretch in cardiac cells just before contraction => important intrinsic mechanism
i) Frank Starling Law of the Heart: states WHY increasing preload increases Stroke Volume: Muscle cells stretched to their optimal length creates the maximum number of cross-bridges between Myosin and Actin Preload is dependent on EDV
- That causes the maximum contraction
End Diastolic Volume
End Systolic Volume

8. ii) Factors That Increases Preload:
i) Preload …
ii) Factors That Increases Preload:
Venous Return = The amount of blood returning to the heart and distending the Ventricles = EDV
Anything that increases Venous Return, increases Preload
Exercise due to squeezing action of muscles on veins and Increased Filling Time from a lowered heart rate both increase Venous Return, and thus increase preload
RESULT: insures equal output of the two Ventricles which prevents back-up of blood
End Diastolic Volume
End Systolic Volume

9. c. Contractility– an extrinsic mechanism
1. Regulation of SV …
c. Contractility– an extrinsic mechanism
= The strength of contraction achieved at a given muscle length (stretch)
i) Is independent of EDV and Muscle stretch
ii) Is dependent on the amount of Calcium that enters the cytoplasm from outside the muscle cells
iii) Extrinsic Factors Influence the level of Calcium
Sympathetic N. S.: when increased, increases Ca
Hormones: Epinephrine, Thyroxine, and Glucagon
d. Afterload: the arterial pressure that the ventricles must overcome to eject blood
- LOWEST IN IMPORTANCE—mainly affecting unhealthy people

10. Regulation of Stroke Volume …
3. Regulation of Heart Rate to Control CO
a. Occurs mainly in unhealthy individuals or when blood volume drops drastically during an emergency
b. Extrinsic Factors that affect Heart Rate
Autonomic N.S.
- Sympathetic
- Parasympathetic
Chemical Regulation– Hormones
Epinephrin
Throxine

11. 4. Autonomic Innervation of the HEART-- Overview
Parasympathetic NS
Cardioihibitory Center of Medulla
Vagus Nerve causes Vagal Tone
Sympathetic NS
Cardioacceleratory Center of Medulla
Vasomotor Center of Medulla
NEXT SLIDE

12. Autonomic innervation of the heart.
Dorsal motor nucleus of vagus
The vagus nerve
(parasympathetic)
decreases heart rate.
Cardioinhibitory center
Cardio-acceleratory center
Medulla oblongata
Sympathetic trunk ganglion
Thoracic spinal cord
Sympathetic trunk
Sympathetic cardiac
nerves increase heart rate
and force of contraction.
AV node
SA node
Parasympathetic fibers
Sympathetic fibers
Interneurons

13. Factors involved in regulation of cardiac output.
Exercise (by
skeletal muscle and
respiratory pumps;
see Chapter 19)
Heart rate
(allows more
time for
ventricular
filling)
Bloodborne
epinephrine,
thyroxine,
excess Ca2+
Exercise,
fright, anxiety
Venous
return
Sympathetic
activity
Parasympathetic
activity
Contractility
EDV
(preload)
ESV
Stroke
volume
Heart
rate
Stroke Volume Regulation
Cardiac
output
Initial stimulus
Physiological response
Result

14. END OF PPT
NEXT
Review Questio

15. Review Questions Which of the following is true about the heart…
Only O2 rich blood leaves the heart.
O2 rich blood leaves the left side, but not the right
Only O2 poor blood enters the heart
O2 poor blood enters the right side and leaves the right side

16. Review Questions Atrioventricular (AV)
__________________ valves prevent blood from going back into the atria while ______________ valves open to allow blood into arteries during ventricular contraction. The ___________ circuit delivers blood to the lungs and the ____________ circuit delivers to the rest of the body.
semilunar
pulmonary
systemic

17. Review Questions SA
Heart rate is controlled primarily by the _____ node because it spontaneously depolarizes at a faster rate than any other part of the conduction system.
Parasympathetic fibers ____________ heart rate by ______ - polarizing the typical lower limit of the pacemaker potential by ____________ extra K+ channels.
Sympathetic fibers ________ heart rate by, among other things, ____________ the pacemaker potential.
decreases
hyper
opening
increase
depolarizing

18. P-Q interval takes longer Ventricular depolarization
Review Questions
If the impulse from the SA node to the AV node is delayed, how would that effect the ECG?
What does the QRS complex indicate?
Interference of signal transmission from SA to AV node is known as ________________.
P-Q interval takes longer
Ventricular depolarization
heart block

19. Review Questions sinoatrial (SA)
The pacemaker of the heart is known as the _____________ node. The ____________________ node coordinates the slightly delayed contraction of the ventricles. Blood then travels away from the heart via the ____________ to the systemic system and the _______________ _____________ to the lungs.
atrioventricular (AV)
aorta
pulmonary artery
Figure 11.6

20. Preload, Contractility, Afterload Positive chronotropic
Review Questions
Stroke volume = ________________ - _______________
What are 3 factors that effect SV?
____________ _____________ factors include anything that increases heart rate like heat or the Atrial Reflex.
End Diastole Vol (EDV) End Systole Vol (ESV)
Preload, Contractility, Afterload
Positive chronotropic

22. Review Questions
Contraction of heart muscles is clinically referred to as _____________; relaxation is referred to as _____________.
Maximum blood pressure occurs during…
Ventricular diastole
Atrial systole
Atrial diastole
Ventricular systole
What is EDV?
systole
diastole
End Diastole Volume

24. Overview: Autonomic Control
Cardiovascular Center in Medulla
Parasympathetic: Cardioinhibitory Center normally in control of Heart at rest:
 Vagus nerve (= Vagal Tone)
Stroke volume controlled by EDV
Sympathetic:
Cardioacceleratory Center takes over Heart during stress and emergencies 
↑ HR via stimulation of SA node
↑ SV via ↑ Contractility (which ↓ ESV)
Vasomoter Center-- normally in control of blood vessel diameter at rest