Download blood flow - OCPS TeacherPress

(HOW THE HEART WORKS)
HEART PHYSIOLOGY
HEART SOUNDS
HEART SOUNDS


Blood turbulence from closing valves
2 sounds:


Lubb (closing of valves between atria and
ventricles)
Dupp (closing of valves after ventricles)
HEART
SOUNDS
Heart
physiology
• Internal pacemaker regulates
beating of heart by setting a
rhythmic electrical excitation
1. Begins in (1) sinoatrial node (in
right atrium)
2. to atrioventricular node
(2)(between atria) to
3. bundle of His (3)to
4. right and left bundle branches
(interventricular septum towards
apex) (4) to
5. Purkinje fibers (from apex
upward) (5)
This “wave” of activity
is picked up by an
electrocardiogram (ECG)
ELECTROCARDIOGRAM
(ECG or EKG)


Recorded electrical currents of heart
Determine healthy heart



P wave: atrial depolarization (contraction
follows)
QRS complex: ventricular depolarization
T wave: ventricular repolarization (start
relaxing)
BLOOD FLOW
pulse
• Alternating expansion
and recoil of an artery
• Wrist pulse = radial
artery
• Neck pulse = carotid
artery
Blood
pressure
• Generated by contraction of
ventricles
• Pressure exerted by blood
on walls of a blood vessel
• Highest in aorta; falls as
distance from left ventricle
increases
• Bp, as a vital sign,
measures pressure in
aorta/large arteries
Blood
pressure
• 2 measurements: systolic (heart
contraction) and diastolic (relaxation)
pressure. EX. 120/80
• Affected by cardiac output and peripheral
resistance
Cardiac output
• Stroke volume x heart rate
• Stroke volume (SV) = amount of blood
ejected from heart each minute.
• HR = # of beats per min.
resistance
• Affected by
– diameter of blood vessel:
– Blood viscosity (ratio of rbc
to fluid): increase by
dehydration, polycythemia;
decrease to anemia,
hemorrhage
– Total blood vessel length:
obesity
• What does blood pressure
measure?
• What factors can raise blood
pressure?
Systolic
Diastolic
FACTORS AFFECTING
BLOOD FLOW


Vol. of blood through any tissue for a given
time period.
Factors:



Cardiac output: heart rate x stroke volume
(amount of blood per minute)
Blood pressure
Resistance



Size of vessel diameter
Blood viscosity
Total blood vessel length
HYPERTENSION
High blood pressure


Major cause of heart failure and stroke
Causes:




Overweight
Excessive alcohol
Lack of exercise
Diet:


high saturated fat (meat/butter)*****, high salt, low minerals (potassium,
calcium)
Stress
******** newest science indicates processed food is
to blame, not saturated fat