Transcript Unit 8 Notes

Unit 8 Notes
Cardiac Muscle
• Cardiac muscle can contract spontaneously and
independently, even if all nervous connections
are severed
• Different muscle cells in different areas have
different rhythms
– Atrial cells: 60 beats/min
– Ventricular cells: 20-40 beats/min
• Because of this, we need a controlling system to
regulate & coordinate contractions!
What controls the heart beating?
• 2 controlling systems
– Nerves of Autonomic Nervous System
• Acts like “brakes” and “accelerators”
– Intrinsic Conduction System
• AKA nodal system
• Enforces a contraction rate to keep
everything together
Parts of Intrinsic Conduction System
• Sinoatrial Node (SA
node) - the pacemaker;
where the action
potential originates,
starting each heartbeat
• As action potential
moves, contraction of
atria is stimulated
• Atrioventricular Node
(AV node) - receives
action potential from SA
node and sends along
to…
Parts of Intrinsic Conduction System
• Atrioventricular Bundle
(Bundle of His) –
branches off into right
and left bundle branches,
and then sends action
potential along to…
• Purkinje Fibers – action
potential received begins
ventricular contraction at
apex and continues
contraction back up
toward atria, helping to
eject blood into
pulmonary trunk or aortic
arch
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/
chapter22/animation__conducting_system
_of_the_heart.html
The Cardiac Cycle
•
•
•
•
Refers to one complete heartbeat
Systole – heart contraction
Diastole – heart relaxation
Since most of pumping done by ventricles,
terms usually refer to ventricles (unless
otherwise stated)
• Normal length of cycle: 0.8 seconds
– Translates into 75 beats/min (average)
The Cardiac Cycle
• First heart sound or “lub”
– Atrioventricular valves close at beginning of
ventricular systole
• Second heart sound or “dub”
– Aortic and pulmonary semilunar valves close at
beginning of ventricular diastole
• http://highered.mcgrawhill.com/sites/0072495855/student_view0/
chapter22/animation__the_cardiac_cycle_
_quiz_1_.html
Electrocardiogram
• Electrodes placed on the
surface of the body
• Action potentials through
myocardium during
cardiac cycle produces
electric currents that can
be measured
• http://video.about.com/h
eartdisease/Electrocardi
ogram.htm
Electrocardiogram
• Pattern
– P wave
• Impulse moves across atria
(depolarization/contraction)
– QRS complex
• Spread of impulse to
ventricles (depolarization/
contraction)
• Atria repolarization/
relaxation
– T wave:
• Ventricle repolarization/
relaxation
• End of electrical activity
Cardiac Arrhythmias
• When any electrical activity of the heart is
irregular
Types of Cardiac Arrhythmias
• Heart Block
– AV node damaged
– Ventricles beat at their own
rate (slower)
– Slower heart beat can lead
to ischemia: lack of blood
flow to heart
– Leads to fibrillation: rapid,
uncoordinated movement of
heart muscle (= cardiac
arrest, death)
– Artificial pacemakers
usually implanted to correct
problem
Types of Cardiac Arrhythmias
• Tachycardia
– Resting heart rate above 100 bpm
• Bradycardia
– Resting heart rate below 60 bpm
• Heart Palpitations
– Premature Atrial Contractions
• Misshapen “P” Wave
– Premature Ventricular Contractions
• Misshapen “QRS” Complex / T Wave
Heart Murmurs
• Heart Murmurs: unusual sounds from
heart (besides normal “lub-dub”)
– Often indicate valve problems
– If valve does not close, “swishing” sound from
blood flowing back
– If valve is narrowed (stenosed), “rushing”
sound
Heart Murmurs
• Doctors will
listen at
different
locations on
your chest to
see if valves
are functioning
properly
Now, let’s talk about blood flow in
the rest of the body!!!
The Vascular System:
Taking Blood to the
Body and Back
The Vascular System
• Arteries – carry blood away from the heart
– Branch into Arterioles
– Pulmonary Arteries - carry deoxygenated blood
– Systemic Arteries – carry oxygenated blood
• Capillaries- exchange
– One cell layer thick!
– Oxygen and nutrients cross to cells
– Carbon dioxide and wastes cross into blood
• Veins – carry blood back to the heart
–
–
–
–
Branch into Venules
Pulmonary Veins – carry oxygenated blood
Systemic Veins – carry deoxygenated blood
Has valves internally!
Vascular System Anatomy
• Veins & Arteries have three layers (tunics)
– Tunic interna
– Tunic media
– Tunic externa
• Opening through which blood flows is
called lumen
Vascular System Anatomy
Arteries
Direction Blood Away from
of flow
Heart
Pressure Higher
Veins
Blood to Heart
Walls
Thicker
Thinner
Wall
Layers
Lumen
Tunica media
thicker than tunica
externa
Smaller
Tunica externa
thicker than tunica
media
Larger
Valves
No valves
Valves
Lower
Vital Signs
Vital Signs
•
•
•
•
•
Pulse
Blood Pressure
Respiratory Rate
Body Temperature
All indicate the efficiency of the system
Pulse
• Pulse – pressure
wave of blood
• Monitored at
“pressure points”
where pulse is
easily felt
• Measured on
arteries because
pressure is strong
enough to be felt
Pulse
• Radial pulse and Carotid pulse most
common (helps to have the artery close to
the surface & hard surface to press it on)
• Average pulse is 65-80 beats per minute
• Pulse influenced by activity, postural
changes, and emotions… stress… tests…
homework… you know 
• Pressure points can also be used as
compression point if trying to stop blood
flow
Blood Pressure
• Measurements by health professionals are
made on the pressure in large arteries
(usually the brachial artery)
• Pressure in blood vessels decreases as
the distance away from the heart
increases (not feeling the pressure created
by the left ventricle as much!)
Blood Pressure
• Systolic Pressure (heart ventricles
contract)
• Diastolic Pressure (heart ventricles relax)
• Blood Pressure= systolic/diastolic
• Normal= 120/80
Measuring Arterial Blood Pressure
Changing Blood Pressure
• Temperature
– Heat has a vasodilation effect
– Cold has a vasoconstricting effect
• Chemicals
– Various substances can cause increases or
decreases
• Diet
Blood
Blood Facts
• Only fluid tissue in human body
• Blood heavier than water and 5 times
thicker
• Slightly basic – pH approximately 7.4
• Temperature slightly higher than body
temperature (100.4°F)
• Approximately 6 quarts (1.5 gallons) in
adult
•
Blood Facts
• Blood stays in a closed system except…
– White blood cells travel in and out of the blood
stream (lymphatic system)
– Water and solutes (ions, nutrients, etc) travel
in and out of the blood stream
Blood Functions Include…
• Distribution & Transport
– Respiratory Gases
– Nutrients
– Wastes
– Bacteria, Viruses, Toxins, etc.
• Regulation and Maintenance
– Hormonal Regulation
– pH balance (blood is a buffer!)
– Temperature
Blood Functions Include…
• Protection
– Clotting
– Immunity
Composition of Blood
• Plasma – 55% of blood
– Mostly water (90%)
– Plasma proteins
• Albumin – pH
• Clotting Proteins
• Antibodies - defense
–
–
–
–
–
Salts (electrolytes)
Nutrients
Waste Products
Hormones
Gases
Composition of Blood
• Formed Elements 45% of blood
– Erythrocytes (Red
Blood Cells)
– Leukocytes (White
Blood Cells)
– Plateletes
Formed Elements
• Erythrocytes (RBC)
– No nucleus, very few
organelles
– Contains hemoglobin
• Iron-containing protein
that helps transport
oxygen
– Biconcave disk
• Increases surface area
for gas transport
– Outnumber WBC 1000
to 1
– Formed by red bone
marrow
Formed Elements
• Leukocytes (WBC)
– Only complete blood cell; contain nucleus and
organelles
– Needed for defense
– Can slip in and out of blood vessels where
needed for immune response
– Also created in bone marrow
– Types of WBC…
Formed Elements
• Types of WBC
– Granulocytes: contain granules
• Neutrophils: most common WBC, active
phagocytes (destroy harmful particles or cells)
• Eosinophils: kill parasitic worms, allergies
• Basophils: contain histamine (vasodilator)
Basophil
Neutrophil &
Eosinophil
Formed Elements
• Types of WBC
– Agranulocytes: no
granules
• Lymphocytes:
produce antibodies,
fighting tumors &
viruses
• Monocytes: largest
WBC, fight chronic
infections
Monocyte
Lymphocyte
Formed Elements
• Platelets
– Not cells, but rather fragments
– Important in blood clotting
Steps to Blood Clotting
• 1. Vessel damage,
blood loss; collagen
fibers exposed
• 2. Vascular spasm to
decrease blood loss;
Platelets become
“sticky” and cling to
fibers
Steps to Blood Clotting
• 3. Anchored
platelets signal to
attract more
platelets; Platelet
plug forms
• 4. Coagulation;
fibers reform
http://health.howstuffworks.com/humanbody/systems/circulatory/blood3.htm
Blood Transfusions
• Body can only compensate for a certain
amount of blood loss
– Loss of 15-30% of blood: weakness
– Loss of over 30%: severe shock, usually fatal
• Therefore, we need to replace the blood
when it is lost!
– Blood treated with an anticoagulant (prevents
clotting) can be refrigerated at 4°C for about
35 days
Blood Transfusions
• However, blood must be compatible with
your body!
– All plasma membranes of RBC bear certain
proteins (antigens) which are unique
– We also have antibodies looking for antigens
– We can tolerate our own antigens, but if we
get different antigens from another person,
antibodies will attack RBC!
– This causes RBC’s to clump (agglutination)
Blood Transfusions
• Agglutination is bad because…
– Small blood vessels will clot
– Oxygen won’t get delivered to tissues
– Kidney tubules will block and cause kidney
failure
• While there are 30 common RBC antigens
in humans, some antigens cause a worse
reaction than others
ABO Blood Groups
• Based on if type A antigen or type B
antigen is inherited
• Lack of either of these antigens is called
type O
• When blood is transfused, only receive
antigens (not antibodies) from donor
Blood that
can be
received
A, O
B, O
A, B, AB, O
(Universal
Recipient)
O
(Universal
Donor)
In Summary…
•
•
•
•
O can give to all
A can give to A and AB
B can give to B and AB
AB can give to AB only
•
•
•
•
O can receive from O only
B can receive from B and O
A can receive from A and O
AB can receive from all
Rh Blood Typing
• Named because of the presence or
absence of Rh antigens (originally studied
in Rhesus monkeys)
– Rh+: have antigen
– Rh-: don’t have antigen
• Rh antibodies are not automatically
formed in Rh- individuals; blood must be
exposed to Rh+ blood to develop
antibodies against it
Rh Blood Typing
• Rh+ person can get either + or – blood
because they have no antibodies!
• However, if Rh– person receives Rh+
blood, antibodies can form
– Okay for first transfusion, but in 2nd
transfusion, antibodies will attack new Rh+
blood = bad.
• In summary:
– Rh+ can get Rh+ or Rh– blood
– Rh– should only get Rh– blood
Rh Blood Typing
• Also, if Rh- woman
becomes pregnant with
Rh+ baby, she can
develop antibodies
– The antibodies would
then attack the blood
of a second Rh+ baby
= BAD!
– Mom can be treated
so that this doesn’t
happen
Erythroblastosis fetalis
Cardiovascular Conditions
Review of some terms…
• Ischemia: lack of blood flow to the heart
• Fibrillation: rapid, uncoordinated
movement of the heart muscle due to
ischemia
• Cardiac Arrest: blood flow to body ceases,
leads to death
Conditions
• Arteriosclerosis
– Any hardening of
arteries, which leads
to narrowing of artery
lumen, and so
insufficient blood
supply to the organ it
feeds
• Atherosclerosis
– Hardening specifically
due to plaque buildup
• A Balloon
Angioplasty or
a Stent can
be used to
treat the
previous
conditions
• http://www.nhlbi.nih.gov/health/dci/Diseas
es/Angioplasty/Angioplasty_All.html
Conditions
• Thrombosis: blood clot in an intact blood
vessel
– Can happen in arteries or veins
– Most common in veins of the legs
– Compression stocking and anticoagulants can
help
Conditions
• Embolism: occurs
when a thrombosis
migrates from one part
of the body to another
(via circulation) and
causes a blockage
Conditions
• Pulmonary Embolism:
when an embolism blocks
the pulmonary arteries
specifically
• http://video.about.com/qui
tsmoking/PulmonaryEmbolism.htm
Conditions
• Varicose Veins: veins
have become enlarged
and twisted
– Can happen as blood pressure in
veins increases and gets blocked
around the valves
– More common in women; linked
with heredity; becomes worse
with obesity and prolonged
standing
– http://video.about.com/s
eniorhealth/VaricoseVeins.htm
Conditions
• Hypertension: high blood pressure
– Systolic above 140 and diastolic above 90
– Can indicate other issues
– http://video.about.com/highbloodpressure/Blo
od-Pressure.htm
• Your chances of developing high blood pressure are also
higher if you:
– Are overweight
– Are a man over the age of 45 / woman over 55
– Have a family history of high blood pressure
• Other things that can raise blood pressure include:
– Eating too much salt
– Drinking too much alcohol
– Not getting enough potassium in your diet
– Not doing enough physical activity
– Taking certain medicines
– Having long-lasting stress
– Smoking
Conditions
• Coronary Heart/Artery Disease (CHD)
– End result of plaques within the walls of the
arteries that supply the myocardium with
oxygen
– #1 killer in the US
– Often leads to myocardial infarction
– Angina (heart pains) can indicate CHD
Conditions
• Myocardial Infarction
– AKA Heart Attack
– A coronary artery is blocked, and so the heart
muscle itself is starves of oxygen
– ischemia  fibrillation  cardiac arrest 
death
– If the person survives, their muscle tissue can
be severely damaged
For your information…
• 1.5 million heart attacks suffered in the
United States each year
• 500,000 will be fatal
• The total direct and indirect cost of
cardiovascular disease (CVD) and stroke
in the United States for 2008 is an
estimated $448.5 Billion. By comparison,
in 2007, the estimated cost of all cancer
related costs, both benign and malignant
was only $219 billion.
• http://video.about.com/heartdisease/HeartAttack.htm
• http://video.about.com/heartdisease/HeartBypass.htm
• http://video.about.com/heartdisease/LVAssist-Device.htm
Conditions
• Congestive Heart Failure
– The heart muscle is weakened (due to CHD,
myocardial infarctions, hypertension, viral
infections, or stresses such as childbirth &
chemo/radiation)
– Decline in pumping efficiency
– Inadequate circulation in body – leading to
cyanosis and swelling of limbs/abdomen
– Because blood not being pumped to body,
can get backed up in lungs, causing
shortness of breath
• http://video.about.com/heartdisease/Cong
estive-Heart-Failure.htm
Conditions
• Aneurysm
– Blood filled bulge of blood
vessel
– Usually an artery
– Caused by disease or weak
vessel wall
– Base of brain and aorta most
common places to happen
– When it bursts = BAD.
Conditions
• Heart Block
– AV Node is damaged, which means ventricles
beat at their own rate, which is slower than
normal
– ischemia  fibrillation  cardiac arrest 
death
– Pacemaker can be implemented
Conditions
• Hemophilia
– The body’s ability to control
blood clotting is impaired,
as missing factors prevent
fibrin formation in a clot
– Sex-linked, x-chromosome
disorder; usually shows up
in males, but inherited from
the mother
– Patients can be regularly
infused with clotting factor
• Hemophilia in European
royalty is featured
prominently and thus is
sometimes known as
"the royal disease".
Queen Victoria passed
the mutation to her son
Leopold and, through
several of her daughters,
to various royals across
the continent, including
the royal families of
Spain, Germany, and
Russia.
Conditions
• Anemia
– Blood has abnormally low
oxygen-carrying capacity
– Different types include…
• Aplastic anemia – destruction or
inhibition of red bone marrow
• Hemorrhagic anemia – result of
acute or chronic loss of blood
• Sickle-Cell anemia – cells take on
abnormal shape, which decreases
the cell’s flexibility and oxygen
capacity