Lab 3

Question 1

What is an ECG?

Answer 1

recordings of electrical signal from electrodes that usually placed on skin surface

Question 2

Describe the structure of the heart

Answer 2

4 chambered with two surfaces: ventral = auricular and the atrial surface = subsinuosal interventricular groove

Question 3

What is the pericardium?

Answer 3

pericardium covers the heart

• pericardial sac is double layeres and closed sac that surrounds the heart, a continuation of the sternum and diaphragm forms the phrenicopericadrial ligament
• consists of two tissues layers: visceral pericardium covers the surface and parietal pericardium covers the inner surface of parietal sac = both tissues continuous until the vessel enter or leaves the heart

Question 4

What is the gap between the parietal and visceral surfaces?

Answer 4

pericardian cavity filled with fluid to reduce firction between the layers as heart pumps

Question 5

Where is the myocardium located?

Answer 5

below pericardium, in two lower chambers of the heart called the ventricles

Question 6

What is the tip of the heart called?

Answer 6

apex (only the left ventricle extends all the way to the apex)

Question 7

What is coronary artery?

Answer 7

lies in the grooves in front of the heart and branches over the front and back side of the heart to supply fresh blood with oxygen and nutrient to the heart muscle itself

Question 8

What is pulmonary artery?

Answer 8

a big blood vessel branches and carries blood to the lungs to receive oxygen and can be found curving out of right ventricle (upper chamber to your left)
like next to aorta

Question 9

What is the aorta?

Answer 9

major vessel located near the left atria and behind pulmonary trunk going to the lungs
curved part: aortic arch
branches from the aortic arch is a large artery that supplies blood to the upper and rest of body

Question 10

What are the pulmonary veins?

Answer 10

vessel return oxygenated blood from lungs to left atrium (upper chamber on the right)
quite thin

Question 11

What are the inferior and superior vena cava?

Answer 11

located on the left side of heart and connect to the right atrium: deoxygenated blood enters body through these vessels into the right receiving chamber
do not contain valves to control blood flow

Question 12

Where are the tricuspid valves and what do they do?

Answer 12

between right atrium and right ventricle
consists of 3 leaflets and long fibres of connective tissue called chordae tendinae that attach it to the papillary muscles of the heart

allows blood flow from the right atrium into the right ventricle during diastole. when the heart is in systole, ventricular pressure increases until it is greater than the pressure of the atrium causing the tricuspid to snap closed

Question 13

What is diastole?

Answer 13

period when heart is relaxed

Question 14

What is systole?

Answer 14

when heart begins to contract

Question 15

Where is the septum?

Answer 15

on right side of the right ventricle

thick muscular wall separates the right side to the left side of heart

Question 16

What is special about the pulmonary semilunar valve?

Answer 16

one way valve that controls blood flow away from the right ventricle at the entrance to this blood vessel

Question 17

What is the bicuspid or mitral valve?

Answer 17

controls blood flow between upper left atrium and lower left ventricle
two leaflets and blood flows from the left atrium into the left ventricle during diastole

Question 18

What is the role of left ventricle?

Answer 18

very thick, heart chamber responsible for pumping blood throughout entire body

Question 19

Describe the aortic valve.

Answer 19

three leaflets from left ventricle into aorta (half moon shape)

Question 20

What does the cardiac cycle consist of?

Answer 20

systole (contraction) and diastole (relaxation)

atria contract while ventricles relax

Question 21

What is a pulse?

Answer 21

wave of contraction transmitted along arteries

Question 22

What does the ECG reflect?

Answer 22

depolarization progressing from SA through atrial muscles to AV node, bundle of His and Purkinje fibers through muscles bringing overflow of currents

Question 23

What is an ECG wave?

Answer 23

isoelectric line with positive and negative deflections (pointed bits of the ECG)

Question 24

What do ECG intervals and segments enable us to measure?

Answer 24

timing of the different phases (more rounded waves)

Question 25

Describe all the waves of ECG: P, QRS, T, PR, ST, TP

Answer 25

P wave: depolarization of atria
QRS complex: depolarization of ventricles, repolarization of atria
T wave: repolarization of ventricles
PR segment: AV nodal delay
ST segment: ventricular contraction 
TP interval: diastole

Question 26

What is the definition of blood pressure?

Answer 26

the force of blood pushing against the walls of the arteries

Question 27

When is your blood pressure at its highest and lowest?

Answer 27

highest: when the heart beats, pumping blood = systolic pressure
eg. rises when you wake up from sleep, excited, nervous or active

lowest: when the heart is at rest, between beats blood pressure falls = diastolic pressure
eg. when sleeping

usually written is 120/80 mmHg

Question 28

Why is the blood pressure cuff placed on the right arm?

Answer 28

so the “artery” label is on the brachial artery

the index finger and middle finger is used to feel the pulse at the brachial artery on the inside of the elbow

Question 29

What is the procedure of measuring an ECG?

Answer 29

first calibrate:

a) pump cuff bub until 160 mmHg
- record a resting ECG
- record an ECG on the same person during exercise