The cardiovascular system 2

Question 1

the main difference between the large and small arteries.

Answer 1

Large Arteries: These include the aorta and its major branches. They have thick walls with a high content of elastic fibers, allowing them to stretch and recoil with each heartbeat. This elasticity helps to maintain a consistent blood pressure and flow.

Small Arteries (Arterioles): These are smaller in diameter and have more smooth muscle relative to their size. This muscle allows them to constrict or dilate, playing a crucial role in regulating blood flow and pressure to specific tissues

Question 2

neuromuscular cells in the myocardium which initiate and conduct impulses.

Answer 2

a. The sinoatrial node (SA node)
b. Atrioventricular node (AV node)
c. Atrioventricular bundle (AV bundle) or bundle of His
d. Conducting myofibers (Purkinje fibers)

Question 3

The heart conduction system

Answer 3

The heart’s electrical activity is primarily controlled by an intrinsic system of specialized cardiac muscle cells called pacemaker cells.

However the heart can be stimulated or depressed by nerve impulses from the brain and hormones.

Question 4

Atrioventricular node (AV node)

Answer 4

Located in the wall of the
atrial septum near atrioventricular valves. They are stimulated
by electrical impulses that spill over from the SA node.

Question 5

The sinoatrial node (SA node)

Answer 5

They are known as pacemakers because they initiate impulses (cardiac cycle) by sending electrical impulses to both atria.

Question 6

Atrioventricular bundle (AV bundle or bundle of His)

Answer 6

Originates from AV node and located at the top of interventricular septum.

Question 6

Purkinje fibres

Answer 6

If the heart’s primary pacemaker, the sinoatrial (SA) node, fails, Purkinje fibers can take over and generate their own electrical impulses.

Question 7

The cardiac cycle

Answer 7

Refers to the complete relaxation and contraction of both the atria and ventricles which last approximately 0.8 sec.

Question 8

One complete cardiac cycle consists of

Answer 8

• atrial systole: contraction of the atria
• ventricular systole: contraction of the ventricles
• complete cardiac diastole: relaxation of both atria and ventricles