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Beat Still My Heart
Chapter 10 – Heart Sounds and Blood Pressure
Heart Sounds

The “lubbdubb” sound
made by your
heart is caused
by the closing
of the heart
valves
Heart Sounds
When your heat pumps . . .
Lubb Sound
 the ventricles contract, blood is forced into the arteries (aorta
and pulmonary artery),
 the atrioventicular (AV) valves close and the lubb sounds is
produced
Dubb Sound
 The atria contract and blood is squeezed into the ventricles
 The semil-lunar valves close and the dubb sound is produced

murmur -valves don’t close properly and blood leaks past

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumpi
ng.html
Cardiac Output


Cardiac output - the amount of blood
that flows from each side of the heart /
minute
Two Factors
– stroke volume
– heart rate
Cardiac Output

Stroke Volume
– the quantity of blood
pumped with each
beat ~ 70ml

Heart Rate
– is the number of
times the heart beats
per minute
Cardiac Output =
Heart Rate x Stroke Volume
= 70 beat/min x 70 ml/beat
= 4900 ml/min
Cardiac Output

Problem:
– Patrick has just finished exercising and in
order for his heart to keep up with the
increased oxygen demands it is pumping at
150 beats per minute. Patrick’s heart can
deliver 70ml of blood per beat. What is
Patrick’s cardiac output?
Heart rate X Stroke volume
150 beats/min X 70ml/beat
10500ml/min or 10.5L/min
Blood Pressure

Sphygmomanometer
– measures blood pressure
– gauge that measures the pressure that blood
exerts during ventricular contraction (systolic
blood pressure) ~ 120 mm Hg
– also measures pressure during ventricular
relaxing (diastolic blood pressure) ~ 80 mm Hg

Why would internal hemorrhaging
(bleeding) cause diastolic blood pressure to
drop?
Blood Pressure

Two factors affecting blood pressure
1. Cardiac output
–  cardiac output,  blood pressure
2. Arteriolar Resistance
–  diameter causes a  blood pressure
–  diameter causes a  blood pressure
How to measure your blood pressure:

http://www.wikihow.com/Check-YourBlood-Pressure-with-aSphygmomanometer
Hypertension



Caused by increased resistance to
blood flow which results in increased
blood pressure
High blood pressure can lead to
weakened blood vessels
Major cause is diet, but may also be
hereditary
Regulation of Blood Pressure

Nervous system responses cause either
increased outflow of blood from arteries
(sympathetic NS) or decrease heart rate
and stroke volume (parasympathetic
NS)
Response to Exercise

NS stimulates adrenal gland to release
adrenaline (epinephrine)
– This stimulates the release of RBC’s
– Increased RBCs = increased O2 transport
– Adrenaline also increases heart rate and
breathing which increases O2 transfer rate
through body
Thermoregulation
To Do:

Textbook Questions p. 335 #2, 5, 7, 10