Download cirulatory system SYHS

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
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 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
• 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 – 11 (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.
Right ventricle/ left ventricle/ right atria/ left atria/ aorta/ lungs/ vena cava(2)/
pulmonary vein/ capillaries (2)
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)
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
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
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
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
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(when the heart
contracts)
– Diastolic: pressure during ventricular relaxation(when the
heart muscle is resting between beats and refilling with
blood
• 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