Lab 3 Flashcards
What is an ECG?
recordings of electrical signal from electrodes that usually placed on skin surface
Describe the structure of the heart
4 chambered with two surfaces: ventral = auricular and the atrial surface = subsinuosal interventricular groove
What is the pericardium?
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
What is the gap between the parietal and visceral surfaces?
pericardian cavity filled with fluid to reduce firction between the layers as heart pumps
Where is the myocardium located?
below pericardium, in two lower chambers of the heart called the ventricles
What is the tip of the heart called?
apex (only the left ventricle extends all the way to the apex)
What is coronary artery?
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
What is pulmonary artery?
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
What is the aorta?
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
What are the pulmonary veins?
vessel return oxygenated blood from lungs to left atrium (upper chamber on the right)
quite thin
What are the inferior and superior vena cava?
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
Where are the tricuspid valves and what do they do?
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
What is diastole?
period when heart is relaxed
What is systole?
when heart begins to contract
Where is the septum?
on right side of the right ventricle
thick muscular wall separates the right side to the left side of heart
What is special about the pulmonary semilunar valve?
one way valve that controls blood flow away from the right ventricle at the entrance to this blood vessel
What is the bicuspid or mitral valve?
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
What is the role of left ventricle?
very thick, heart chamber responsible for pumping blood throughout entire body
Describe the aortic valve.
three leaflets from left ventricle into aorta (half moon shape)
What does the cardiac cycle consist of?
systole (contraction) and diastole (relaxation)
atria contract while ventricles relax
What is a pulse?
wave of contraction transmitted along arteries
What does the ECG reflect?
depolarization progressing from SA through atrial muscles to AV node, bundle of His and Purkinje fibers through muscles bringing overflow of currents
What is an ECG wave?
isoelectric line with positive and negative deflections (pointed bits of the ECG)
What do ECG intervals and segments enable us to measure?
timing of the different phases (more rounded waves)
Describe all the waves of ECG: P, QRS, T, PR, ST, TP
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
What is the definition of blood pressure?
the force of blood pushing against the walls of the arteries
When is your blood pressure at its highest and lowest?
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
Why is the blood pressure cuff placed on the right arm?
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
What is the procedure of measuring an ECG?
first calibrate:
a) pump cuff bub until 160 mmHg
- record a resting ECG
- record an ECG on the same person during exercise
