The heart as a pump

Question 1

Recognize the anatomical location and structure of the heart

Answer 1

Location -Middle cavity of the chest
Anatomy - Three walls of the heart: 1. Epicardium (external layer), 2. The myocardium (middle layer), 3. Endocardium (Inner layer)
The pericardium surrounds and protects the heart.

Question 2

describe the structural and functional characteristics of cardiac muscle tissue

Answer 2

Cardiac muscle: Branching fibers with special gap junctions (intercalated disks) allow cardiac muscle cells to contract a syncytium
Cardiac muscle tissue are self-excitable and autorhythmic. Repeatedly generate spontaneous action potentials that then trigger heart contractions. The fibers in the SA node are the natural pacemaker of the heart.
Signals from the nervous system and hormones can modify the heart rate

Question 3

describe the importance of the electrical conduction system of the heart

Answer 3

The action potential initiated by the SA node travels along the conduction system and spreads out to excite the ‘working’ atrial and ventricular muscle fibres called contractile fibres.

Question 4

Define vascular resistance

Answer 4

is the opposition to blood flow due to friction between blood and the walls of the vessels. The higher the resistance, the smaller the blood flow

Question 5

Define intercalated disks

Answer 5

microscopic identifying features of cardiac muscle

Question 6

Define syncytium

Answer 6

a single cell or cytoplasmic mass containing several nuclei, formed by fusion of cells or by a division of nuclei

Question 7

Define pericardium

Answer 7

the membrane the surrounds the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane

Question 8

Define cardiac cycle

Answer 8

One cardiac cycle consists of the contraction (systole) and relaxation (diastole) of both atria, rapidly followed by the systole and diastole of both ventricles.

Question 9

Define viscosity

Answer 9

measurement of the thickness and stickiness of a patient’s blood.

Question 10

Describe the relationship between blood volume, pressure and flow