Physiology of the Heart

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Bell WorkLabel the parts of the conduction system of the heart.

• Sinoatrial node (pacemaker) ->

• Atrioventricular node ->

• Bundle of HIS ->

• RT and LT Bundle branches ->

• Purkinje fibersBundle of HIS

Physiology of the Heart

• State Standards • 35) Outline the structure and functions of the

anatomy of the cardiovascular system, paying special attention to the musculature of the walls, the chambers, and the valves of the heart and blood vessels. Locate and demonstrate the circulation of blood through the heart; describe the phases and importance of the cardiac cycle and how heart rate and cardiac output relate to one another. Listen to heart sounds, either digitally or with a stethoscope, to identify the normal and abnormal sounds made during the cardiac cycle. Explain the causes for abnormal sounds encountered.

Objectives

– Determine the cardiac output of the heart by practicing its calculation and relate it to blood pressure

– Determine the mechanism of how heart sounds are made and the best places to hear them

– Determine normal vs. abnormal heart sounds

– Practice obtaining pulse and auscultating heart sounds

https://medlineplus.gov/ency/anatomyvideos/000021.htm

• Conduction system of the heart:

• group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract

• What tells these cells to do this?

PHYSIOLOGY OF THE HEART

• Stroke volume: – Amount of blood ejected (from

ventricles) with each beat of the heart (usually 60ml)

• Cardiac output: – The amount of blood ejected from heart

per minute• Stroke Volume x Heart Rate= Cardiac Output

• SV x HR = CO

Discussion

• Calculate the following Cardiac Outputs.

• SV of 6ml, HR of 89

• SV of 8ml, HR of 53

• SV of 6ml, HR of 74

• How should you be labeling your answers?

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Cardiac Output and Blood pressure

• Cardiac output and blood pressure are directly related.

• An increase in cardiac output results in an increased blood pressure.

• Discussion

– What is the most common place to measure blood pressure?

– What tools do we need?

Where would you take a blood pressure if…

• Your patient has a dialysis graft in his left arm?

• Your patient has amputated arms?

• Your patient has IV’s in both brachial regions of the arms?

• Can you take a blood pressure in your ankle region? Toe region?

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

SOUNDS OF THE HEART

• Lub dub sounds - Sounds made by the valves during the cardiac cycle– Lub - sound made when the tricuspid

and bicuspid valves close between the atria and ventricles

– Dub - Caused by the aortic and the pulmonary valves closing between the aorta and pulmonary arteries

Heart Sounds

• Lub– 1st sound heard (closing of the

tricuspid and bicuspid valves)

– Referred to as S1 and heard loudest at the apex of the heart.

– Discussion:• Where is the apex of the heart?

• Point to it on your own chest.

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Heart Sounds

• Dub

– 2nd sound (closing of the pulmonary valves and the aortic valves)

– Referred to as S2

Discussion

– Where are the pulmonary and aortic valves located in relation to the apex of the heart? Use medical directional terms.

• What does auscultation mean?

.

Normal heart sounds and where to locate them.

• https://www.youtube.com/watch?v=M8HYmaDpWpE (24 sec)

• https://www.youtube.com/watch?v=ZiU97u2a6oI (6 min)

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Abnormal Heart Sounds

• Murmurs

– Turbulent blood flow in the heart

• Due to improper closing of the valves

– The third heart sound or S3 is a rare and extra heart sound that occurs soon after the normal two "lub-dub" heart sounds (S1 and S2). S3 is associated with heart failure.

Abnormal Heart Sounds Continued

– The fourth heart sound or S4 is an extra heart sound that occurs immediately before the normal two "lub-dub" heart sounds (S1and S2)

– It is caused by the atria contracting forcefully in an effort to overcome an abnormally stiff ventricle.

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Abnormal Heart Sounds

https://www.youtube.com/watch?v=WjP1fDjbE_s (7 min)

****Write down each one that is noted on the video. We will research these later.

© 2004 Delmar Learning, a Division of Thomson Learning, Inc.

Activity

Complete Station 2 on the Cardiac Lab Activity:

-auscultation of the heart sounds with a stethoscope

-palpating pulse sites

**Your lab partner may prefer to hold the stethoscope

***Complete your Stroke Brochure***

Individual Activity

• 1st: Refer back to the abnormal heart sounds you documented.

• Research what the cause (related disease or disorder) might be.

• 2nd: Explain possible consequences of blood pressure that is too high and too low.

• Exit Ticket:

• What does S2 refer to?

• How do cardiac output and heart rate relate to each other?