Transcript 6) Blood Flow and Blood Pressure

Cardiovascular System &
Circulation
Reading: Chapter #13
A. Heart location
-in thoracic cavity
A. Heart location
-the heart is surrounded by the pericardial sac which has 3
layers:
1) visceral pericardium -next to the heart (inner
layer)
-also called epicardium
2) parietal pericardium
(makes…)
-middle layer
-serous membrane
-lubrication
3) fibrous pericardium
-tough outer layer
Pericarditis = -inflammation of the pericardium
-pericardium begins sticking together
-very painful (feels like heart attack)
B. HEART STRUCTURE
-hollow organ with 4 internal chambers
B. STRUCTURE
1) Wall -there are 3 layers to the wall of the heart:
a) endocardium -innermost layer
-very smooth layer
b) myocardium -middle layer (variable thickness)
-made of cardiac muscle tissue
-has its own blood supply
c) epicardium = visceral pericardium (serous
membrane)
B. STRUCTURE
2)
Chambers w/ valves -2 atria on top
-2 ventricles below
a) Right side:
1)
2)
3)
4)
5)
R atrium
tricuspid valve
chordae tendineae
R ventricle (thin)
papillary muscles
b) Left side of heart:
1)
2)
3)
4)
5)
L atrium
bicuspid valve
chordae tendineae
L ventricle (thick)
papillary muscles
c) Blood flow
Superior & Inferior Vena Cavae
R atrium
R Ventricle (passing tricuspid valve)
Pulmonary trunk (passing pulmonary semi-lunar valve)
LUNGS (gas exchange)
Pulmonary veins (2 L and 2 R)
Left atrium
Left ventricle (via bicuspid valve)
Aorta (via semi-lunar valve)
C. BLOOD VESSELS
We did this in the blood chapter.
D. ROUTES OF BLOOD FLOW
1) Pulmonary Circulation
-low O2 blood is pumped out to lungs from the _____
ventricle
-via the pulmonary __________
-blood returns to heart via pulmonary ____________(O2
rich)
-blood returns to the heart from the lungs via
_________________
-newly oxygenated blood enters the _______ __________
2)
Systemic Circulation
-oxygenated blood leaves the heart from the ______
ventricle
-this blood is pumped out to the body via the
_____________
-blood returns to the heart via the vena cavae to the __
________
3. Coronary circulation
Independent blood vessels supply oxygen &
nutrient rich blood to the myocardium.
Coronary arteries branch off the aorta.
Deoxygenated blood returns to the Right Atrium
via cardiac veins.
If cardiac veins are blocked:
a) Ischemia= small stroke, blocked BV in brain
b) Myocardial infarction=heart attack-symptoms?
Non-invasive treatments? Invasive treatments?
4. Cerebral Circulation
Stroke (CVA)= the brain is deprived of
oxygen, there are 4 types.
1. thrombus: blood clot in the brain
2. Embolus: blood clot breaks loose & is
carried by blood flow
3. Hemorrhage: great loss of blood
4. Aneurysm: weak spot in an arteryballoons up & may rupture
Warning signs of a stroke & risk
factors
Sudden numbness or weakness ________
Sudden confusion ___________________
Sudden trouble _____________________
Sudden trouble _____________________
Sudden severe _____________________
RISK FACTORS: High BP, _____________
___________________________________
5. Fetal Circulation
-Does the fetus breathe? What circuit isn’t
needed?
Foramen Ovale:
-hole b/w R & L atrium
-most blood by-passes R ventricle &
lungs
-at birth a flap covers this hole
Ductus Arteriosus:-shunt b/w pulmonary artery & aorta
-at birth, duct constricts & becomes a
ligamentum arteriosus
6. Hepatic Portal Circulation
Blood from the capillaries in the intestines
travels to the LIVER
E. CARDIOVASCULAR PHYSIOLOGY
1) Cardiac cycle (repeated ~ 72 times/min)
a) systole =
-contraction/emptying phase
-pressure goes up
-volume goes down
b) diastole =
-relaxation/filling phase
-pressure goes down
-volume goes up
Ventricular contraction
& atrial relaxation
Ventricular relaxation
& atrial contraction
2) Heart valves and sounds
-the heart valves insure one-way flow of blood in the heart
-when the valves close, they produce the “lubb-dupp” sound
a) AV valves prevent back flow to the atria  “lubb”
b) Semilunar valves prevent back flow into ventricles 
“dupp”
Auscultation = listening to body sounds
Murmur = valve(s) are leaky & blood flows backward
Semi-Lunar Valves – superior view
Failure of the valves may require surgical valve
replacement.
3) Heart Conduction System (ELECTICAL)
-the heart has its own electrical conduction system
-the heart will keep beating even w/out any nerve connection
SA node =
-pacemaker (upper R atrium)
-where the impulses originates (~72
beats/min)
SA node (pacemaker) sends out ~72 beats/min.
Impulse travels across atria
AV node (atrioventricular)
“Bundle of His” (also called the A-V bundle)
Left & Right Bundle Branches w/in Interventricular
Septum
Purkinje Fibers
Myocardium Stimulated to Contract
If SA node stops working: -AV node takes over
-heart rate ~ 60 beats/min.
If AV node malfunctions:
-much more common
-myocardial cells take over
-heart rate ~20-30 beats/min.
Pacemakers can be inserted to regulate the heart
beat.
Definitions:
Ectopic focus - heart beat originates in a place other than SA
node.
Arrythmias -irregular heart rate, abnormal rhythm
Bradycardia
-slow heart rate
-rate < 60 beats/min
Tachycarda
-fast heart rate
-rate > 100 beats/min
Arrhythmias
Normal ECG
(70-80 bpm)
Tachycardia
(>100 bpm)
Bradycardia
(<60 bpm)
4) ECG (EKG) = electrocardiogram
-sensors on skin measure electrical activity in heart (not
mechanical)
-totally non-invasive
Each wave has a meaning:
a) P wave = depolarization of atria
b) QRS wave = depolarization of ventricles
c) T wave = repolarization of ventricles
d) atrial repolarization occurs during QRS complex
(masked)
4) ECG (EKG) (con’t)
e)
ECG’s can be used to diagnose heart diseases
Sudden heart attack  death
5) Cardiac Output (Q)
-Amount of blood pumped by the left ventricle/minute.
-Varies depending upon need.
a) Q = Heart Rate (HR) x Stroke Volume (SV)
b) HR = ~72 beats/min
-controlled by pacemaker
c)
SV
= volume pumped with each beat
= about 70 ml
Q=
Q=
Q=
HR x SV
72 beats/min x 70 ml/beat
5040 ml/min (about 5 liters/min)
What can cause a change in
Q?
(Q = HR x SV)
1.
ANS (sympathetic & parasympathetic stimulation)
2.
Starling’s Law of the Heart
-“The heart will pump all of the blood that comes in”
-More blood comes into ventricle  ventricle contracts
harder
-So, regular aerobic activity  stronger myocardium
6) Blood Flow and Blood Pressure
Blood flows from areas of greater pressure
to areas of lesser pressure
6) Blood Flow and Blood Pressure (con’t)
-Pulse rates = -rate of heart beat
-measured by counting pulse waves in major
arteries
6) Blood Flow and Blood Pressure (con’t)
-Blood Pressure =
-strength of pressure waves in arteries
-measured indirectly w/ a
sphygmomanometer
How to use the Sphygmomanometer:
Skip for now….we’ll go over this later before the lab.
F. CARDIOVASCULAR ABNORMALITIES
1) Hypertension = high blood pressure:
a) borderline values are 140 to 150/90 to 100
mmHg
b) a “silent” disease
c) can damage to vessels, heart, kidneys
d) most due to unknown cause
e) treatment  weight loss, exercise, medication
f) NO CURE!
Optimal Blood Pressure = 120/80 mmHg
Risk factors for developing heart disease
Major Risk
Factors That
Cannot be
Changed
Heredity
Major Risk
Factors That
Can Be
Changed
Cigarette
Smoking
Sex (male)
Hypertension
Race (African
American)
Blood
Cholesterol (HDL
vs LDL)
Diabetes
Age
Obesity
Contributing
Factors
Stress
END