Download The Circulatory System

The Circulatory System
Interesting Facts
•The heart beat is strong enough to squirt
blood 30 feet
•The longer a boy’s ring finger is, the less
likely they are to have a heart attack
(according to one study)
•The human heart beats ~35 million times
per year
•The heart pumps ~1,000,000 barrels of
blood in a lifetime
•Most heart attacks occur between 8-9 a.m.
Interesting Facts
•The blue whale has the largest heart – it weighs ~
one ton
•The hummingbird has a heart that beats 1000
times per minute
•Your entire volume of blood goes through your
entire body once every minute
•Humans have ~60,000 miles of blood vessels in
their bodies (more than twice the circumference of
the earth!)
•Your heart beats 100,000 times and pumps ~2000
gallons of blood every day
•Pig and baboon hearts have been transplanted into
humans
Cardiovascular System
•Heart, vessels, blood
•Function: transport
gases, nutrients,
wastes, hormones
The Heart
•Size of a fist; less than a
pound
•In thorax; flanked by lungs;
rests on diaphram
•Top: base
•Bottom: apex
•Double-layered sac
covering the heart
•Outer layer anchors
heart in chest
•Inner layer
(epicardium)
attached to heart
wall
•Lubricating fluid in
pericardial space
(between layers)
reduces friction
Pericardium
Pericarditis
Decrease in
fluid causes
layers to cling
& rub against
each other
resulting in
pain &
decreased
efficiency of
heart
Pericardial Tamponade
•Bleeding into
pericardial space
after chest trauma
•Excess blood
restricts expansion of
heart during pumping
•Causes shock or
death if not corrected
Heart Wall
3 layers:
•Epicardium: outer wall joined with pericardium
•Myocardium: the actual cardiac muscle that
contracts
•Endocardium: lines heart chambers & vessels
Heart Chambers
Four chambers:
•2 atria: top of
heart – receive
blood from veins
•2 ventricles:
bottom of heart –
pump blood
through arteries
Heart Chambers
Heart sounds (Luppdupp) from valves closing
•Septum: divides left
from right heart
•Valves: keep blood
flowing in one
direction
•Four valves:
• 2 AV valves,
• 2 semilunar valves
Atrioventricular
Valves
AV valves: between atria
and ventricles
•Bicuspid (mitral) valve:
on the left
•Tricuspid valve: on the
right
•When valves are open blood drains from atria into
ventricle
•When ventricle contract, valve flaps are forced shut,
blocking blood from reentering atria
Semilunar Valves
•Located in arteries leaving
ventricles
•Pulmonic valve: at base of
pulmonary artery
•Aortic valve: at base of aorta
•When ventricles contract, valves are forced
open & let blood flow
•When ventricle relaxes, backflow of blood fills
flaps of valve & forces them to shut
•Arteries: carry
blood away from
the heart
•Veins: carry
blood to the heart
•Capillaries:
connect arteries
to veins &
exchange gases
with tissues
Blood Vessels
Arteries
•Carry blood at high
pressure
•Very thick, stretchy walls
that expand in size
•Most carry oxygenated
blood (red)
•Damaged arteries spurt in
time to heart beat
Arteries
•Aorta: largest vessel
(diameter of a
garden hose) –
receives blood from
left ventricle
•Arteriole: smaller
vessels connecting
arteries to capillaries
•Carry blood at low
pressure
•Have valves to
prevent backflow of
blood against gravity
•Most carry deoxygenated blood
(purple)
•Damaged veins ooze
blood
Veins
•Vena Cava: dump all
blood from the body into
the right atria
• superior vena cava:
receives blood from
upper body
• inferior vena cava:
receives blood from
lower body
•Venules: smaller vessels
connecting veins to
capillaries
Veins
Capillaries
•Connect arteries and veins
•Walls are one cell thick
•Allow exchange of gases through thin walls
• Drop off oxygen delivered from heart by arteries
• Pick up CO2 and send it to the heart thru veins
How Blood Travels thru Vessels
heart
artery
arteriole
capillary
venule
vein
heart
•Narrowing of vessel
lumen due to
plaque/fat formation
on inside of walls
•Causes: diet high in
fat, cholesterol, salt;
inactive lifestyle;
smoking
•Risks: high BP,
enlarged heart,
embolus blocking
circulation; stroke
Atherosclerosis
Coronary
Artery
Disease
•When Atherosclerosis affects the arteries that
supply the heart muscle
•Symptoms: short of breath after simple
exertion, angina (chest pain)
•Risk: MI, cardiac arrest, death
How is CAD
treated?
•Medication
•Angioplasty (balloon
surgery) – balloon is
inserted and inflated
in blocked vessel to
compress fatty mass
against the artery
wall
How is CAD Treated?
•Stent – wire mesh inserted into the artery to expand its
lumen
•Coronary Artery Bypass – arteries are removed from
leg and grafted into the heart to restore circulation
Vessel Disorders
Varicose Veins:
twisted, dilated
veins resulting from
pooling of blood
due to long periods
of standing,
obesity, or inactivity
Vessel Disorders
Thrombophlebitis:
inflammation of a
vessel due to clot
formation & poor
circulation. Clot can
become an embolus
if freed.
•Weaking in the wall of a vessel, causing it to
balloon outwards.
•Rupture of the site causes
Aneurysm
• Stroke (if in the brain)
• Death (in a large artery – aorta).
•Coronary arteries exit the aorta & supply
oxygen/blood to heart muscle (myocardium)
•Coronary veins pick up & return deoxygenated
blood from myocardium
Cardiac
Circulation
Defects in
Coronary
Circulation
•Angina Pectoris: impaired circulation to myocardium
causes oxygen deprivation & pain
•Myocardial infarction: “heart attack” – blockage of
circulation to section of myocardium causes the muscle
to infarct (die)
Pulmonary Circulation
•Right ventricle pumps deoxygenated blood
through pulmonary artery to the lungs
•The blood picks up O2 from the lungs and
dumps CO2 into the lungs
•Oxygenated blood is returned to the left
atrium thru the pulmonary vein
Systemic
Circulation
•Oxygenated blood
is pumped from left
ventricle thru aorta
to the body
•Blood dumps
oxygen into tissues
and picks up CO2
•Deoxygenated
blood travels from
body to vena cava to
the right atrium
The Circulation
Play the Game
Number the parts 1 – 17 (just write the
correct order on a piece of paper). Pass your
paper to a classmate when you finish. We will
grade them as a class.
Congestive Heart Failure
•Heart is ‘worn out’ from hypertension, multiple
MI, atherosclerosis, or age
•Heart pumps too weakly to meet tissue needs
•If one side is weaker than the other, blood will
back up in system
Congestive Heart Failure
•Left ventricle is failing:
• Pulmonary congestion
• Pulmonary edema
(blood in lungs)
causes suffocation
•Right ventricle is
failing:
• Peripheral congestion
• Edema in distal body
parts (ankles, feet)
Pulmonary
Edema
Pulmonary
edema (A);
normal lung
(B)
Peripheral Edema
Swelling of feet and ankles due to CHF
Conduction System of the Heart
Heart is under two types of control:
•Autonomic Nervous system
• Sympathetic: speeds up contractions
• Parasympathetic: the “brakes” that slows
down contractions
•Intrinsic Conduction System
• Also called “nodal system”
• Heart determines its own rate of contractions
Intrinsic Conduction
System
•Nodes are heart tissue that
stimulate heart muscle to
depolarize (contract)
•Depolarization moves from base to apex
•Different areas of the heart have different
nodes, each with a different rate
•Node rate gets slower as it moves downwards
•Faster nodes will override slower nodes
Nodes (you need to know these)
3 Stages:
•SA node fires, atria
contract (depolarize)
•Impulse travels to AV
node, then travels thru
bundle of His, bundle
branches, & Purkinje fibers
– ventricles contract
(depolarize)
•Contraction of ventricles
has ‘wringing’ action,
pushing blood upward and
out through large arteries
•Heart muscle repolarizes
Parts of the
Conduction
System
SA node:
•“The Heart’s Pacemaker”
•In atria
•Normally sets the pace of 60 – 70
•SA can increase rate when stimulated by
drugs, fever, or sympathetic NS (exercise,
stress, emotion)
AV Node:
•Between atria &
ventricles
•Special tissues transmit signal from SA to AV
node
•Intrinsic rate: 40 - 60
Bundle of His:
•Transmits impulse
to ventricles
•Rate: 30 – 40
beats/min
Bundle Branches:
•Within ventricular
muscles
•Rate: 20 – 30
beats/min
Purkinje fibers:
•Terminal end of
branches
Parts of the
Conduction System
What if Damage Occurs?
•If SA node is damaged or its signal is
blocked, the AV node takes over setting the
pace (40-60/min)
•If AV node is next damaged, the bundles
set the rate (20 – 40/min)
What is a Pacemaker?
If heart is unable
to generate impulse,
or pace is too slow,
mechanical
pacemaker is
surgically implanted
to provide artificial
impulses
Electrocardiogram
(ECG/EKG)
•Electrical
impulses in heart
are measured with
ECG
•Electrical activity
is translated into
waves
Electrocardiogram (ECG/EKG)
•P Wave: atria depolarize
•QRS complex: ventricles
depolarize
•T wave: repolarization
•Heart Monitor hooked up with pads on chest
•Abnormalities in ECG used to diagnose heart
damage
•Diagnostic signs: changes in shape of wave,
distance between waves, lack of waves…
Abnormalities
in ECG
Irregular Heart Rhythms
•Tachycardia: heart is beating too fast
•Bradycardia: heart is beating too slow
•Heart Block: no connection between atria &
ventricles – ventricles beat at their own rate
•Ventricular Fibrillation: heart is ‘shivering’ – no
contractions or pulse (cardiac arrest)
•Asystole: dead heart – no electrical activity
Comparing Rates
•Normal Sinus Rhythm
•Sinus Bradycardia
•Sinus Tachycardia
•Elevated ST segment (sign of a MI)
•Ventricular Tachycardia
•Heart Block
•PVC (premature ventricular fibrillation)
•Ventricular Fibrillation
•Asystole
Cardiac Cycle
Cardiac Cycle: The events within
one heartbeat. Three main stages:
•Mid-to-late diastole: SL valves are
closed, AV open; atria contract;
blood is forced into ventricles
•Ventricular systole: ventricular
pressure forces AV closed; SL
forced open; blood rushes out of
ventricles; atria relax & refill
•Early diastole: SL shut; AV open;
ventricles relax and refill passively
Heart Sounds
•Cardiac cycle heard with a stethoscope
•Two sounds: “lub dup” (pause) “lub dup”
(pause) …..
• Lub = closing of AV valves (ventricular systole)
• Dup = Closing of semilunar valves (between
ventricular systole & diastole)
•Murmurs: abnormal heart sounds that
usually indicate valve problems
Valve Disorders
•Leaky Valves:
caused by
incompetent or
deformed valves that
force the heart to repump blood because
of backflow
Stenosis
Valves are stiff and do not open completely.
Heart has to pump harder
Murmur: stenosis
•The most
common valve
disorder
(5-10% of people)
•Mitral valve
opens
(prolapses) into
atrium when
shutting &
allows blood
backflow
Mitral Valve Prolapse
Cardiac Output
•Cardiac Output: the amount of blood
pumped by each side of the heart per
minute
•Cardiac output = heart rate X stroke volume
•Stroke volume = the amount of blood
pumped with each contraction
What is the cardiac output if….
HR = 75 bpm; SV = 70 ml/beat?
This is the normal cardiac output for a resting
adult.
How is the output affected with exercise?
Do you think it increases or decreases?
What affects Stroke Volume?(you
don’t have to write this down)
Increase in Stroke volume:
•Increased venous blood return
• exercise (muscles force blood into heart)
• Slow hr (more time to fill ventricles)
Decrease in stroke volume
•Decreased venous return
• Hemorrhage (less blood volume)
• Tachycardia (not enough time to fill)
What affects Heart Rate?(you don’t
have to write this either)
Increase:
•Decline in SV (heart
compensates by hr)
•Babies and kids
•Females
•During exercise
•Sympathetic NS
Decrease:
•Parasympathetic NS
•Getting older
•Males
•Being fit (heart is more
efficient)
•Cold temperatures
Taken to assess overall health status
•Arterial pulse
•Blood Pressure
•Respiratory Rate
•Temperature
•Alternating expansion
and recoil of arteries
with each heart beat
•Measured in beats per
minute
•Normal resting pulse:
60 – 100 bpm
•Taken at pulse points:
place where pulse is
easily palpated (felt)
Arterial Pulse
Pulse Points
Can also be
used as
pressure points
to stop bleeding
Blood Pressure
•Pressure of the blood against artery walls
•Measured as systolic/diastolic (ex. 120/80)
• Systolic: pressure at peak of contraction
• Diastolic: pressure during ventricular relaxation
•Can be taken by:
• Auscultation (listening for pulse)
• Palpation (feeling for pulse)
•Normal: 100 + age / 60-90
•Cardiac Output (blood pumped per min)
•Peripheral Resistance
• friction inside vessel that hampers flow of blood
• Usually results from narrowing of arteries
What
Determines the
BP?
What affects BP
Increases BP:
•Atherosclerosis
•Thick blood
•Drugs/nicotine
•Obesity
Decreases BP:
•Shock/blood loss
•MI
•Drugs
•Physical fitness
Problems with BP
•Hypotension (low BP):
• Systolic < 90mm/Hg
• Cause: MI; warning sign of shock; athletes
•Hypertension (high BP)
•
•
•
•
•
Systolic >140; Diastolic >90
Heart is forced to work hard for extended time
Vessels damaged due to higher pressure
Causes: obesity, diet, exercise, smoking, genes
Risks: heart attack, stroke