Download The Cardiac Cycle

IB Assessment Statement
6.2.3 Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing
valves.
Instructions
1. Open the application skitch on your computer.
2. Make a cycle flow chart of the flow of blood out the heart and body.
3. ☐Squares should represent parts (chambers, heart blood vessels) of the heart.
4. Circles should represent valves
5. Δ Triangles should represent capillaries of the body (lung capillaries, body capillaries)
6. Blue lines with arrows should connect low oxygen areas, and show the correct
sequence and direction of blood flow
7. Red lines with arrows should connect high oxygen areas, and show the correct sequence
and direction of blood flow
8. Please include the following.
a. Lung capillaries.
b. Pulmonary vien
c. Left atrioventricle valve
d. Right atrioventricle valve
e. Pulmonary artery
f. Right atrium
g. Left atrium
h. Aorta
i. Vena cava
j. Right ventricle
k. Left ventricle
l. Body capillaries
m. Right semilunar valves
n. Left semilunar valves.
GHB 2006
Cardiac Cycle: Mechanical Events (Right Side)
Put the following notes in the correct order
As the cardiac cycle is continuous,…
…above the pressure in the right atrium so that the atrio-ventricular
valves…
The final phase of the cycle is ventricular diastole.
As the pressure in the right ventricle falls further,…
…gives an extra push to send the last of the blood into the ventricle.
…pulmonary artery, and the semi-lunar valves open.
… the pressure in the pulmonary artery so that the semi-lunar valves
close.
At the start of atrial systole, the atrio-ventricular valves…
… and into the right ventricle. The contraction of the right atrium…
As the ventricles relax, the pressure falls below…
…it falls below the pressure in the right atrium, so…
Blood then flows into the pulmonary artery.
… by convention, we usually start with atrial systole.
The next stage is ventricular systole.
… a description of it could begin anywhere. However…
… are open and blood flows from the vena cava, through the right atrium…
As the right ventricle contracts, the pressure in the right ventricle
rises…
…the atrio-ventricular valves open again, and…
…close. As the right ventricle continues to contract, the pressure in it
rises above that in the…
… the right ventricle starts to fill with blood again.
GHB 2006
Make one for the Left side NOW for another group
GHB 2006
Triggering Contraction
Oops! Supply the words which have been obscured.
Muscle contracts when excited by an electrical signal called an action potential.
Cardiac muscle is myogenic – it can generate its own action potential. (Skeletal
muscle is neurogenic – the impulse comes from the nerves.)
The action potential starts in a patch of muscle in the right atrium called the sino-atrial
node or SAN. The SAN produces an action potential about 70 times each minute.
This action potential then rapidly spreads through the walls of the atria, causing them
to contract.
A band of non-conducting fibrous tissue prevents the action potential form spreading
directly form the atria to the ventricles. The only path for the action potential is via a
patch of tissue called the atrio-ventricular node (the AVN), then through conducting
fibres called the Purkyne fibres.
These fibres conduct the action potential rapidly down through the septum – it then
spreads upwards through the walls of the ventricles, so the ventricles contract from
the bottom up.
As conduction through the AVN is slow, there is a 0.12 to 0.20 second delay between
the start of atrial contraction and the start of ventricular contraction.
GHB 2006