The Circulatory System

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The Circulatory System
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• Functions of the Circulatory System
• To circulate oxygen and nutrients to the
• cells.
• To remove metabolic wastes from the
• cells.
• To circulate hormones throughout the
• body.
• To facilitate immune response.
• To maintain bodys internal environment.

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In a child, the human heart is about the size of
his fist, but in an adult, about two fists in
size. It is located in the mediastinum of
the thoracic cavity, posterior to the sternum and
anterior to the thoracic vertebrae. About 2/3s
of the mass of the heart is to the left of
the midline of the body (anatomical position).
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Cool Heart Facts
At rest, the heart muscle works twice as hard as
the calf muscle of a person who is
sprinting. Each day, the average heart beats
100,000 times, pumping about 2,000 gallons (7,571
liters) of blood. In the average lifetime, that
is 2.5 billion beats! In one day, your heart
pumps the 6 quarts of blood in the body (5.6l)
about 12,000 miles! It pumps about 1 million
barrels of blood in a lifetime, 3 supertankers
full!
http//www.texasheartinstitute.org/anatomy.html
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• The heart itself has three layers
• the endocardium (inside layer) is in contact
  with the blood passing through the heart.
• the myocardium (middle layer) is the thick
  muscular layer which gives the heart the strength
  of its contraction.
• the epicardium (outer layer) which is in contact
  with the pericardium or sack that surrounds the
  heart.

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• The Pericardium
• A double-layered membrane which surrounds the
  heart like a sac. The outer layer surrounds the
  roots of your heart's major blood vessels and is
  attached by ligaments to your spinal column,
  diaphragm, and other parts of your body.
• The inner layer of the pericardium is attached to
  the heart muscle ( epicardium). A coating of
  fluid separates the two layers of membrane,
  letting the heart move as it beats, yet still be
  attached to your body.

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The heart has four chambers. ATRIA.are the two
upper receiving chambers of the heart. The
right side receives deoxygenated blood from the
body through the VENA CAVA. The left side
receives oxygenated blood from the lungs through
the pulmonary vein.
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The heart has four chambers (continued) Ventricle
s are the two lower pumping chambers of the
heart. The right side pumps deoxygenated
blood through the pulmonary artery to the
lungs. The left side pumps oxygenated blood
through the aorta to the body. Pumping is a
result of the heart muscle contracting.
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The Heart Valves Between the right atrium and
right ventricle is the tricuspid valve. Between
the left atrium and the left ventricle is the
bicuspid or mitral valve. The Vessel Valves (
Semi-lunar valves) The pulmonary valve prevents
blood flow back into the right ventricle. The
aortic valve prevents blood flow back into the
left ventricle.
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The right side of the heart is responsible for
pulmonary circulation. The left side of the
heart is responsible for circulation to the rest
of the body. The sides are separated by a thick
wall called the Septum.
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• Four types of valves regulate blood flow through
  your heart
• The tricuspid valve regulates blood flow between
  the right atrium and right ventricle. 
• The pulmonary valve controls blood flow from the
  right ventricle into the pulmonary arteries,
  which carry blood to your lungs to pick up
  oxygen. 
• The mitral valve lets oxygen-rich blood from your
  lungs pass from the left atrium into the left
  ventricle. 
• The aortic valve opens the way for oxygen-rich
  blood to pass from the left ventricle into the
  aorta, your body's largest artery, where it is
  delivered to the rest of your body.

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CT
P
The cusps or flaps of the valves are
pulled open by the chordae tendonae which are
anchored in mounds of tissue on the inside wall
of the heart called papillae.
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• The heart's electrical system
• causes the heart to beat.
• controls the heart rate (the number of beats per
  minute).
• has special pathways (conduction pathways) that
  carry the electrical signals throughout the lower
  heart chambers (ventricles) for each heartbeat.

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What is a heartbeat? It is referred to as the
Cardiac Cycle. There are two components
Contraction phase (systole) First atria and then
ventricles contract to force blood out of the
chambers. Relaxation phase (diastole) During
the diastole phase the atria and ventricles are
relaxed and the atrioventricular valves are open.
What causes the lub dub sound of the heart?
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What About Blood Pressue? Systole pressure
against artery walls during contraction This
pressure is affected by volume of blood,
viscosity, and resistance. Diastole pressure
remaining in arteries during rest This pressure
is a function of heart rate, vessel compliance
peripheral blood flow.
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What is a Sphygmomanometer? Instrument which
uses a column of Hg in mm to measure
pressure. How is this done? A cuff is placed
against the brachial (arm) artery, pumped in air
compresses artery, As air is released, the artery
snaps back into place, with a stethoscope one can
hear the blood flow As air pressure against
artery decreases, one loses the flow sound or
diastole Take pressure reading when beat sound
is first heard, take second reading when beat
sound disappears. Systole/diastole 120/80 mm
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The Blood Vessels....
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Arteries

• Have a pulse.
• Have thick walls that do not collapse when empty.
• Carry blood away from the heart.
• Have elastic walls which push blood forward.
• Have larger lumen.
• Blood drawn from an artery is bright orange red.
  Exception?

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Veins

• Lack a pulse.
• Carry deoxygenated blood. Exception?
• Collapse when empty.
• Carry blood to the heart.
• Have valves to prevent backflow.
• Have thinner walls than arteries.
• Blood removed from a vein is a deep burgundy.
• Stretch eight times more than arteries.

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Lymph Nodes
Follicles (A) with the lightly stained germinal
centers. The germinal center is a location of
B-lymphocyte proliferation and the development of
the immune response.
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Capillaries

• Capillary diameter 1 Red Blood Cell
• No body cell is more than a couple cell
• diameters away from a capillary
• Capillaries have holes in their membrane which
  are selective to what goes in and out.
• All capillaries can pass oxygen, carbon dioxide,
  small ions, glucose
• Brain capillaries have low permeability
• except for essentials and lipid soluble
  materials.
• Alcohol is lipid solubleso

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Capillaries
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Blood

• Blood is the fluid of life, transporting oxygen
  from the lungs to body tissue and carbon dioxide
  from body tissue to the lungs.
• Blood is the fluid of growth, transporting water,
  and nourishment from digestion as well as
  hormones from glands that will regulate growth
  and development.
• Blood is the fluid of health, transporting
  disease fighting substances to the tissue and
  waste to the kidneys.

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Plasma is the straw-colored liquid in which the
blood cells are suspended.

• Plasma transports materials needed by cells and
  materials that must be removed from cells
• various ions (Na, Ca2, HCO3-, etc.)
• glucose and traces of other sugars
• amino acids
• other organic acids
• cholesterol and other lipids
• hormones
• urea and other wastes

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Erythrocytes are Red Blood Cells These
transport respiratory gases (O2, CO2). They are
produced in bone marrow cells. They have a
lifespan approximately 120 days. As these cells
age, the membrane gets fragile when they go
through capillaries they will eventually rupture
become trapped in the spleen (so spleen catches
most old RBCs)
Erythrocytes
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Thrombocytes (Platelets)

• Platelets, which are cell fragments, are seen
  next to the "t's" above.
• Platelets are important for proper blood
  clotting.
• Each cubic millimeter of blood should contain
  250,000 to 500,000 of these. If the number is too
  high, spontaneous clotting may occur. If the
  number is too low, clotting may not occur when
  necessary.

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Leukocytes (White Blood Cells) Granulocytes -Bas
ophils contain histamines (cause vasodilation)
and heparin (anticoagulant). -Neutrophils
These cells are capable of phagocytizing foreign
cells, toxins, and viruses. -Eosinophils
Effective against parasitic worms in their larval
form. These cells also phagocytize antigen -
antibody complexes.
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Agranulocytes -Monocytes -Lymp
hocytes
These cells are phagocytic and defend the body
against viruses and bacteria.
These cells play an important role in our immune
response. The T-lymphocytes act against virus
infected cells and tumor cells. The B-lymphocytes
produce antibodies.
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Leukocytes (White Blood Cells) Granulocytes -Bas
ophils -Neutrophils -Eosinophils Agranulocytes
-Monocytes -Lymphocytes
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