Transcript the cardiovascular system

THE CARDIOVASCULAR
SYSTEM
VITAL FUNCTIONS
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pumps 7000 liters of blood / day
beats ~2.5 billion times
to carry O2 from the lungs to the body’s cells
to carry nutrients from the digestive system
to the cells
• to remove cellular waste
• to form clots / to coagulate (an anticoagulant
prevents clotting)
YOUR BLOOD:
FLUID TRANSPORT
• blood is a tissue made of
fluid, cells, & fragments of cells
– fluid = plasma, 55% of the total volume of blood
– cells = red & white blood cells suspended in plasma
• usually 45% of the total volume of blood
• this percentage is called the hematocrit (HCT)
– fragments = platelets suspended in plasma
YOUR BLOOD:
FLUID TRANSPORT
• red blood cells (RBC’s): erythrocytes
– round, disk-shaped cells
– make up 44% of the total volume of blood
– produced in the red bone marrow of the ribs,
humerus, femur, sternum, and other long bones
red blood cells (RBC’s): Erythrocytes
– only have a nucleus in the early stages of
development
– active about 120 days, then broken down in
the spleen & liver by macrophages via
phagocytosis
– contain hemoglobin, an iron-rich protein
molecule that binds to O2
– oxygenated RBC’s carry oxygen from the
lungs to the body’s cells
Anemia:
= too few RBC’s or
too little
hemoglobin.
Person is pale &
lacks energy.
Caused by low
iron intake.
carbon dioxide in the blood:
– 70% of the CO2 combines with water in
plasma to form bicarbonate (affects the pH of
blood)
– 30% is attached to hemoglobin or dissolved in
plasma
white blood cells (WBC’s): leukocytes:
– infection fighters
– play a major role in protecting you from
foreign substances, and from invading
bacteria
– make up 1% of total blood volume
– they are larger than RBC’s & they have a
nucleus
blood clotting:
– platelets help blood to
clot by linking together a
sticky network of protein
fibers called fibrin
– this forms a web over the
wound to catch escaping
RBC’s
– platelets are produced in
bone marrow & last only
1 week
ABO BLOOD GROUPS
• blood surface antigens determine blood
group
– antigen = substances that stimulate an
immune response
– antigens are on the
surface of certain RBC’s
– 2 types of antigens:
A&B
– blood plasma contains antibodies that are
shaped to correspond with the different blood
surface antigens
– the antibodies react with the matching antigen
if they are brought together, resulting in
clumped blood
– you don’t have
antibodies for your
own antigen type
– type A blood has A antigens and anti-B
antibodies
– type B blood has B antigens and anti-A
antibodies
Rh factor = Rhesus factor:
– another antigen which may be present (Rh+)
or absent (Rh-)
– Rh factor is an inherited characteristic
– only 15% of the U.S. population is Rh-
– may complicate pregnancies
• an Rh- mother that is pregnant with a Rh+
baby will make anti-Rh+ antibodies when
their blood mixes at birth
• if she gets pregnant again with another Rh+
baby, her anti-Rh+ antibodies will destroy
RBC’s in the fetus
• prevention: mom is treated with a
substance to prevent the production of
antibodies in her blood at 28 weeks &
again shortly after the birth of the first baby
YOUR BLOOD VESSELS:
PATHWAYS OF CIRCULATION
• 3 main types: arteries, veins, capillaries +
venules & arterioles
• 62,000 miles of blood vessels in your
body!
arteries:
– large, thick walled,
muscular, elastic
blood vessels
– carry blood away
from the heart
under great pressure
– main arteries divide into smaller arteries that
divide into arterioles which eventually branch
into capillaries
capillaries:
– microscopic blood vessels only 1 cell thick
– enables nutrients & gases to diffuse easily
between blood cells & surrounding tissue cells
– form a dense network that reaches virtually
every cell in the body
– join to form venules as
blood leaves tissues
veins:
– venules merge to form veins
– carry blood from the tissues
back to the heart
– less pressure than the arteries
– blood travels against gravity in
some veins, so they are
equipped with valves to
prevent blood flowing
backward
YOUR HEART:
THE VITAL PUMP
• the heart
– a large organ made of cardiac muscle cells
rich in mitochondria
– main function = to keep blood moving
constantly thru the body
• Myocardium = thick layer of muscle in the
walls of the heart
• Pericardium = serous membrane that
encloses the heart
all mammalian hearts have 4 chambers:
• 2 upper chambers = L & R atria
• 2 lower chambers = L & R ventricles
• the atrial walls are thinner & less
muscular than the ventricles because
they perform less work
• the L ventricle works
harder than the R,
so it’s bigger making
the heart lopsided
• a solid septum
separates the whole
R side from the L,
so blood never
mixes
Valves of the heart:
- the tricuspid valve sits between the R
atrium & the R ventricle & it permits blood
to flow thru while preventing backflow
– the bicuspid (mitral) valve sits between the
L atrium & the L ventricle, & does the same
job as the tricuspid
– the bicuspid &
tricuspid valves are
called atrioventricular
– the pulmonary &
aortic valves are
called semilunar
because their cusps
are shaped like half
moons
– the aortic valve sits at the entrance to the
aorta & prevents backflow into the L ventricle
– the pulmonary valve sits at the entrance to the
pulmonary trunk & prevents backflow into the
R ventricle
blood’s path through the heart:
– blood enters the heart thru the atria & leaves
thru the ventricles
– both atria fill up at the same time
– the R atrium receives O2 poor - CO2 rich
blood from the head & body via 2 large veins,
the vena cava
blood’s path through the heart:
– the L atrium receives O2 rich blood from the
lungs via 4 pulmonary veins (the only veins to
carry oxygen-rich blood)
– after the atria fill with blood, they contract &
push it into the ventricles
– after the 2 ventricles
are full, they contract
simultaneously
– the R ventricle pushes O2 poor blood out of the
heart & towards the lungs thru the pulmonary
arteries (the only arteries to carry oxygen-poor
blood)
– the L ventricle pushes O2 rich blood out of the heart
thru the aorta (the largest blood vessel in the body)
to the arteries
PATH OF BLOOD:
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Vena cava (superior / inferior)
Right atrium
Tricuspid valve
Right ventricle
Pulmonary semi-lunar valve
Pulmonary arteries
Capillaries of lungs
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Pulmonary veins
Left atrium
bicuspid valve
left ventricle
aortic semi-lunar
aorta
all body cells
the heart acts as 2 separate pumps,
following 2 pathways :
– pulmonary circulation = the right side of the
heart pumps blood from the heart to the lungs
– systemic circulation = the left side of the
heart pumps blood from the heart to the rest
of the body
heartbeat regulation
– each heartbeat causes a surge of blood to
flow from the L ventricle into the aorta & then
into the arteries = pulse
– best felt in the arm’s radial artery or the neck’s
carotid artery
heartbeat regulation
– heart rate is set by the pacemaker in the
top of the R atrium
• sends an impulse to the atria
• triggers another impulse to contract the
ventricles
– electrocardiograph = a machine
that measures & records these
electrical signals
heartbeat regulation
– electrocardiogram = the reading produced by
this machine
– the ECG is an important tool used to diagnose
abnormal heart rhythms & patterns
blood pressure
= the force that the blood exerts on the blood
vessels
– it rises & falls as the heart contracts & relaxes
– it rises sharply when the ventricles contract =
systolic pressure / systole
– it drops dramatically as the ventricles relax =
diastolic pressure / diastole
blood pressure
• hypertension = high blood pressure =
persistently elevated arterial pressure.
Can be caused by kidney disease, high
sodium intake, obesity, psychological
stress, or arteriosclerosis (hardening of the
arteries)
control of the heart
– the medulla oblongata regulates the rate of
the pacemaker
– sensory cells in the arteries become stretched
when the heart beats too fast which sends a
signal to the medulla oblongata
control of the heart
• if the heart slows too much, blood
pressure drops which signals the medulla
oblongata to speed up the pacemaker
RELEVANT VOCABULARY:
• Pericarditis = inflammation of the pericardium
• Pulmonary circulation = a circuit transporting blood
between the heart & lungs
• Systemic circulation = a circuit transporting blood
between the heart & body tissues
• Myocardial infarction = a heart attack
• Tachycardia = rapid heart rate (100+ beats / min)
• Bradycardia = abnormally slow heart rate (<60)
• Heart murmur = abnormal or unusual heart
sounds, can be due to valve incompetence
• Cardiac output = the volume of blood pumped
out by each side of the heart in 1 min
• Stroke volume = the volume of blood pumped
out a ventricle with each heartbeat
• Congestive heart failure = a progressive
condition occurring when the pumping efficiency
of the heart is depressed so that circulation is
inadequate to meet tissue needs
• Pulmonary edema = blood vessels leak fluid into
the air sacs and tissues of the lungs
• Atherosclerosis = fatty deposits / plaque clogs
the blood vessels, leads to arteriosclerosis
(hardening of the arteries)
• Leukemia = cancer of the white blood cells