NATS 1675 Lecture 20: The Circulatory System continued / Vascular [Blood] Tissue

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24 Mar 2016
Department
Course
NATS 1675 LECTURE #20 The Circulatory System continued / Vascular [Blood]
Tissue
Professor: Robert Crippen
Electrocardiogram (ECG)
It is a recording of the electrical changes that occur in the heart during a cardiac cycle
The various peaks and valleys of one cardiac cycle are labeled/indicated by letters:
P, Q, R, S and T
The P-wave indicates that the atria are about to contract; the S-A node has “fired”
The QRS sequence indicates the ventricles are about to contract; the A-V node has
“fired”
The T-wave indicates the recovery of the ventricles
Blood Pressure
It refers to atrial pressure which changes as the heart goes through its cycle.
Heart beats/contracts about once in 0.8 seconds
Contraction phase is referred to as systole
Relaxation phase is referred to as diastole
The sounds the heart makes are described as lub dup (also lubb dupp and lub
dub)
Lub, the first sound, occurs when increased pressure forces the flaps of the AV-valves to
close. A swishing sound after the lub indicates a heart murmur or leaky valve. Dup, the
second sound, occurs when the ventricles relax and the semilunar valves close due to
back pressure
Systolic pressure is the maximum pressure in arteries during systole
Diastolic pressure is the minimum pressure in arteries during diastole
Angina Pectoris
This results when blood flow to myocardial tissue is reduced because of a partial
blockage of the coronary arteries
Symptoms include a feeling of pressure, squeezing or pain in the chest
Symptoms can be brought on by increased need for blood due to exercise, changes in
one's emotional state or increased altitude (thinner air)
This normally can be alleviated by a nitroglycerin [it is absorbed into the blood and
dilates the vessels] dispensed by a puffer sprayed to the back of the throat
Arteriosclerosis
It is the loss of elasticity and hardening of the arteries
There are several types and they primarily affect the medial layer of the artery
Atherosclerosis
It is the hardening and obstruction of the arteries due to deposition of lipids and other
substances which are referred to as plaque
This condition primarily involves the inner most layer of the artery
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