“Fun” Warm- UpTake about 2 min and name as many song titles as you can that mention each of the following organs:

HeartBrainLungs

StomachIntestine

Liver

Example: “Heart shaped box” By Nirvana“Aqualung” by Jethro Tull

Cardiovascular

System

While intricate and vital……

It is a simple ONE WAY system!

Basic Anatomy- Reference the handout you labeled after yesterday’s test.

• Heart is a pump with 4 chambers.

• 2 Atria on top• 2 Ventricles on bottom • Blood vessels are

tubes.• Veins carry blood TO

heart• Arteries carry blood

AWAY FROM heart

The cardiac cycle

Describing the sequence of events in one heart beat

What does a heart beat sound like?

Cardiac Cycle• One complete sequence of ventricular

systole and diastole• Cycle of events that occurs as the

heart contracts and relaxes• Both sides of heart• Takes approximately 0.8 secs at a

heart rate of 72 beats per minute

Definitions

• Systole = period of ventricular contraction. • Diastole = period of ventricular relaxation.

• NOTE: Normally diastole is longer than systole.

Cardiac cycle• General Principles.

• Contraction of the myocardium generates pressure changes which result in the orderly movement of blood.

• Blood flows from an area of high pressure to an area of low pressure, unless flow is blocked by a valve.

• Events on the right and left sides of the heart are the same, but pressures are lower on the right.

• Why is pressure lower on the right side?

• At what point in the cycle does the blood have the farthest to travel to get back to the heart?

Atrial systole• The heart is full of

blood and the ventricles are relaxed

• Both the atria contract and blood passes down to the ventricles

• The atrio-ventricular valves open due to blood pressure

• 70% of the blood flows passively down to the ventricles so the atria do not have to contract a great amount.

Ventricular systole

• The atria relax.• The ventricle walls

contract, forcing the blood out

• The pressure of the blood forces the atrio-ventricular valves to shut (producing the heart sound ‘lub’)

Ventricular systole

• The pressure of blood opens the semi-lunar valves.

• Blood passes into the aorta and pulmonary arteries.

Diastole• The ventricles relax• Pressure in the

ventricles falls below that in the arteries

• Blood under high pressure in the arteries causes the semi lunar valves to shut. This produces the second heart sound, ‘dub’.

• During diastole, all the muscle in the heart relaxes.

• Blood from the vena cava and pulmonary veins enter the atria.

• The whole cycle starts again.

Electrocardiograms (EKG/ECG)

P = atrial excitation

QRS = excitation of ventricles

T = diastole

Control of the Cardiac Cycle

• Sinoatrial node (SAN) aka pacemaker – top of right atrium

• Atrioventricular node (AVN) – top of the inter-ventricular septum

• Purkyne Tissue – runs down the inter-ventricular septum

SAN, AVN and Purkyne Tissue

SAN, AVN and Purkyne Tissue

Cardiac cycle

Match the letter on the graph to the following events

• Semi-lunar valves open• Atrio-ventricular valves close,• Semi-lunar valves close• Atrio-ventricular valves open

atrio-ventricular valves open

atrio-ventricular valves openatrio-ventricular valves close

atrio-ventricular valves openatrio-ventricular valves close

semi-lunar valves open

atrio-ventricular valves openatrio-ventricular valves close

semi-lunar valves open

semi-lunar valves close