Download The Circulatory System

The Circulatory System
• Recall:
• Cellular respiration: the process of a cell
converting glucose into energy.
• Oxygen is an important reactant required for
this process:
• C6H12O6 + 6O2  6CO2 + 6H2O + energy
• Oxygen needs to get to all parts of the
body!!! This is the main purpose of the
circulatory system!!
FUNCTIONS
1) Regulate body temperature
2) Transport substances around the body
– oxygen from lungs to cells!
– carbon dioxide from cells to lungs (to get rid
of)!
– nutrients (e.g. from intestines) and wastes
(e.g. to kidneys)
– hormones
– infection-fighting white blood cells and
chemicals from immune system
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show video
Components of the circulatory
system
• 1) Heart :  made up of cardiac muscle,
nerve, and connective tissues
pumps blood through the body and back
to lungs
tissues and inner surface covered by
epithelial tissues to protect heart from
damage and allow blood to flow freely.
2) BLOOD
• Blood cells (45%)
– red (transport oxygen) – more 43%
– white (infection-fighting) – 1%
– platelets (help in blood clotting) – 1%
• Plasma (55%)
3) Blood Vessels
• A) Arteries: mostly carry OXYGENATED
(red) blood AWAY from heart.
• B) Veins: mostly carry DEOXYGENATED
(dark red) blood towards the heart.
• C) Capillaries: link arteries and veins
together
Cycle
• Oxygen diffuses
from lungs into
capillaries
• oxygenated blood
goes to heart
where it is
pumped through
the arteries to the
rest of the body
• blood dumps oxygen
into tissues (diffuses
through
capillary walls) and
picks up CO2
• deoxygenated
blood travels through
veins back to heart
which pumps it back
to capillaries in the
lungs
CO2 diffuses into
lungs and is exhaled
Circulatory System
• Summary:
• Main functions:
– 1) regulate body temp
– 2) transport substances around the body
• Components
– Heart, blood, and blood vessels
• Types of blood vessels:
– Arteries (away), veins (towards), capillaries
Arteries
• Carry blood at high
pressure and hence have
• Very thick, stretchy walls
• Damaged arteries spurt
in time to heart beat
• Aorta: largest
artery (diameter of
a garden hose) –
artery through
which heart pumps
blood out to body
• Carry blood at low
pressure
• Have valves to
prevent backflow of
blood against gravity
Veins
Capillaries
• Connect arteries and veins
• Walls are very thin (i.e. one cell thick) to allow for
diffusion (of oxygen into tissues and into CO2
bloodstream)
Blood Vessels
How Blood Travels thru Vessels
Capillaries in the lungs heart
arteries
capillaries in the body veins
heart
capillaries in the lungs
Cardiovascular System
The Heart
• Size of a fist; less than a
pound
• Leans towards left in your
chest, flanked by lungs;
rests on diaphram
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
Heart Diseases:
• Coronary artery diseases: artery can
become blocked by deposits of fat,
cholesterol, etc
• Blood (with oxygen) cannot get to heart
muscle – heart can stop pumping (heart
attack)
• Cause can be genetic or poor diet,
exercise, or habits
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
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 re-pump 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