The Heart

SBI 3U

Ms. Raper

The Heart

• Is a pump• Actually it is TWO pumps• One pump deals with blood to the lungs, the

other pump deals with blood to the body.• Heart is made of Cardiac Muscle• The two sides are separated by a thick wall of

muscle called the SEPTUM• The blood for the two pumps is kept separate in

mammals.

Fetal Heart circulation

• Because the fetus is not using its lungs, the blood is “shunted” between the right and left atria through a hole called the foramen ovale. This usually closes shortly before birth.

• Babies who do not have the foramen ovale closed are born with a “hole in the heart”

This diagram shows the path taken by the blood through the heart.

Use the following link to label the heart.

http://www.bishopstopford.com/faculties/science/arthur/Heart%20drag&drop.swf

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/table22-3_blood_flow_th.jpg

http://learninglab.co.uk/headstart/

Cardiac Muscle

The synchronous beating of the cardiac muscles are controlled by bundles of nerves.

Structure of the Heart.

• Four chambers, 2 upper called ATRIA

2 lower called VENTRICLES

• The Right side of the heart receives deoxygenated blood from the body via the superior and inferior vena cava.

• The Left side receives oxygenated blood from the lungs via the Pulmonary veins

Valves of the Heart• The atria and ventricles are separated by one way atrioventricular

valves.• Between the right atria and right ventricle is the TRICUSPID valve• Between the left atria and left ventricle is the MITRAL valve.• SEMILUNAR valves are found at the base of the PULMONARY

artery and AORTA.• The purpose of the valves is to prevent blood flowing backwards.• Leaking of these valves can result in a heart murmur

Watch the heart valves at this link

• http://www.wellesley.edu/Biology/Courses/111/HeartValves.MOV

Cardiac Cycle - Heart Beat.

• Phase 1 SYSTOLE – Contraction

“Occurs when the Ventricles contract, closing the AV Valves and opening the SL Valves to pump blood into

two major vessels leaving the heart.”

• Phase 2 DIASTOLE – Relaxation

“Occurs when the Ventricles relax, allowing the back pressure of the blood to closed SL Valves and opening

AV valves.” (Mr. Johnson)

http://www.sirinet.net/~jgjohnso/circulation.html

http://www.biologymad.com/HeartExercise/HeartE3.gif

http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_McKinley/f22-11_cardiac_cycle_c.jpg

http://www.owensboro.kctcs.edu/gcaplan/anat2/notes/Notes5%20Cardiac%20Cycle.htm

Check out the following link.

EKG - electrocardiogram• Records the electrical activity of

the heart.• S-A node generates an electrical

impulse that spreads over the two atria causing them to contract.

• S-V node causes the ventricles to contract.

• P to Q represents the small electrical voltage increase due to depolarization when the atria contract.

• The large spike Q-S represents the contraction of the ventricles.

• As the ventricles recover, a small spike at T precedes the next firing of the S-A node

• Check this link

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html

Chemical Regulators of the Heart

• Noradrenaline: increase in CO2 stimulates receptors in the blood vessels. The Medulla oblongata sends impulses to produce noradrenaline, this chemical causes the S-A node to fire more rapidly

• Acetylcholine: increase in blood pressure causes receptors in the blood vessels to send the information to the medulla oblongata which in turn causes the release of acetylcholine. This chemical slows the firing of the S-A node.

Other chemicals that affect the heart….

• Nicotine – increases heart rate• Caffeine - increases heart rate• Amphetamine – increases heart rate• Cocaine – increased heart rate• Anabolic steroids – increased blood pressure.• Barbiturates – slow pulse• Alcohol - decreases heart rate

• http://www.nida.nih.gov/DrugPages/DrugsofAbuse.html

Cardiac Output & Fitness

• Like all muscles, the heart needs exercise• The volume of blood pumped out by the heart is

known as the CARDIAC OUTPUT.• Factors that affect cardiac output are heart rate

and stroke volume• Cardiac output = heart rate X stroke volume

Average person data

• Stroke volume = 70mL

• Heart rate = 70 beats/minute

• Cardiac cycle = 70mL X 70beats/min

• = 4900mL/min

• There is a correlation between heart health and fitness

Relationship between stroke volume, heart rate & and cardiac output

Individual Cardiac output

Stroke Volume

mL/beat

Heart Rate

Beats/min

A 4900 70 70

B 4900 50 98

C 4900 140 35

D 9800 70 140

•C is exceptionally fit has a high stroke volume and maintain a low hear rate.

•B is less fit

•Regular cardiovascular exercise increases the resting stroke volume.

•Fitness is measured by how quickly the heart rate returns to the resting rate before exercise began.

http://www.owensboro.kctcs.edu/gcaplan/anat2/notes/Notes5%20cardiac_equations.htm

Resources that you need to review

• Text – Chapter 9• Mr. Johnson’s biology –chapter 46.• http://www.sirinet.net/~jgjohnso/circulation.html• Professor Fajer – Circulation, Heart & Blood• http://fajerpc.magnet.fsu.edu/Education/

2010/2010_INDEX.HTM• Online Biology Book: Circulation

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html

Check out these

• Biology animations: http://science.nhmccd.edu/biol/index.html

• Anatomy & Physiology II http://science.nhmccd.edu/biol/ap2.html

• Science animations: http://science.nhmccd.edu/biol/animatio.htm

• And especially -http://science.nhmccd.edu/biol/ap2int.htm

• Check out the section on cardiovascular.• Anatomy of the Heart:

http://www.owensboro.kctcs.edu/gcaplan/anat2/notes/Notes5%20Anatomy%20of%20the%20Heart.htm