Blood and the Cardiovascular System

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Blood and the Cardiovascular System

• Chapters 17-19

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Blood Functions

• Distribution
• Delivery of oxygen and nutrients to all body
  cells Transport of wastes to lungs and excretory
  organs Transport of hormones
• Regulation
• Maintenance of body temperature, pH, and adequate
  fluid volume
• Protection
• Prevention of blood loss via clotting prevention
  of infection with the immune system

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Blood

• Only fluid tissue in the body with both cellular
  and liquid components
• Specialized connective tissue where the living
  blood cells are suspended in the non-living
  plasma
• Parts of the blood
• Plasma (55)
• Erythrocytes (42-45)- Red Blood Cells
• Leukocytes (1)- White Blood Cells
• Platelets

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Plasma

• Composed largely of water (90), but also has
  over 100 dissolved solutes (gases, nutrients,
  wastes, proteins, etc.)
• Most common plasma protein is albumin
• Aids in carrying molecules through circulation,
  is a blood buffer, and helps to keep water in the
  bloodstream

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Erythrocytes (RBCs)

• Shaped like flattened disks with depressed
  centers giving it a high surface area good for
  gas exchange
• Have no nucleus and very few organelles
• Contains proteins such as hemoglobin that aid in
  carrying oxygen (do not go through aerobic
  respiration so none of this oxygen is consumed by
  the RBC)
• Protein spectrin gives the cell flexibility so
  that it can move through capillaries

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Erythrocytes (RBCs)

• Functions in oxygen and carbon dioxide gas
  exchange
• Production of RBCs is called hematopoiesis or
  hemopoiesis and occurs in the red bone marrow
• In adults this generally occurs in the axial
  skeleton and girdles and in the proximal
  epiphyses of the humerus and femur

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Erythrocyte Disorders

• Anemia
• An insufficient number of red blood cells
• Possibly due to blood loss, bone marrow failure,
  excessive RBC destruction
• Ex hemorrhagic anemias, hemolytic anemias,
  aplastic anemias
• Low hemoglobin content
• Often related to nutrition (may be diet or
  inability of the body to absorb certain
  nutrients)
• Ex Iron-deficiency anemia, pernicious anemia
• Abnormal hemoglobin
• Globin is misshaped due to genetic variation
• Ex Thalassemias, sickle-cell anemia

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Erythrocyte Disorders

• Polycythemia is an excess of erythrocytes that
  increases blood viscosity
• Polycythemia vera often caused by bone marrow
  cancer
• Secondary polycythemia often caused by
  prolonged exposure to high altitudes and is a
  response by the body to get more oxygen
• Can be treated with blood dilution
• Some athletes do this on purpose (called blood
  doping) to increase oxygen carrying capabilities

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Leukocytes (WBCs)

• Are complete cells who function in the bodies
  defense system
• The circulatory system is their highway and means
  of transportation to where they are needed
• They are able to leave blood vessels in a process
  known as diapedesis
• Once out of the bloodstream, they move through
  the tissue spaces by amoeboid motion following
  chemicals released by damaged cells (called
  positive chemotaxis)
• The body speeds up WBC production when needed
  therefore, having a WBC count over 11,000 tends
  to signify an infection

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Leukocytes (WBCs)

• 2 groups of leukocytes
• Granulocytes
• Neutrophils contain hydrolytic enzymes and are
  active phagocytes (bacterial slayers)
• Eosinophils contain digestive enzymes that tend
  to work against parasitic worms also phagocytize
  inflammatory chemicals related to allergic
  reactions
• Basophils release histamine causing an
  inflammatory response
• Agranulocytes
• Lymphocytes composed of T cells which function
  in immune response and B cells which give rise to
  plasma cells that produce antibodies
• Monocytes aka macrophages defend against
  viruses, bacterial parasites and chronic
  infections

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Leukocyte Disorders

• Leukemias a group of cancerous conditions
  involving WBCs
• The type of cancer will depend on the type of WBC
  involved
• The bone marrow becomes occupied by cancerous
  leukocytes and immature WBCs flood into the
  bloodstream
• This in turn can cause anemia and bleeding
  problems
• Infectious Mononucleosis caused by the
  Epstein-Barr virus
• Causes excessive numbers of agranulocytes, often
  atypical
• Typically runs its course in a few weeks

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Platelets

• Cytoplasmic fragments of large cells called
  megakarocytes
• Function in the clotting process by sticking to
  the damaged site and creating a temporary seal
• This process is called hemostasis and involves 3
  phases
• Vascular spasms (vasoconstriction)
• Platelet plug formation
• Coagulation or blood clotting

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Platelets

• After 30-60 minutes, the clot goes through clot
  retraction
• This processes squeezes serum (plasma) from the
  clot and compacting the clot, drawing the edges
  closer together
• Fibrinolysis also occurs to remove unneeded clots
  when healing has occurred

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Disorders of Hemostasis

• Thromboembolytic conditions
• A clot or thrombus forms in an unbroken blood
  vessel
• This can block circulation or break away and move
  through the bloodstream (embolus) where it can
  obstruct blood flow through a vessel
• Embolism often become lodged in the lungs or
  brain
• This may be more prevalent when there is
  arteriosclerosis, burns, or inflammation or when
  the blood is flowing more slowly due to lack of
  movement
• This can be treated using aspirin, heparin,
  dicumarol, or warfarin / coumadin

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Disorders of Hemostasis

• Bleeding Disorders
• Thrombocytopenia
• Too few platelets causes spontaneous bleeding
  from small blood vessels
• Impaired liver function
• Liver cannot / does not produce the procoagulants
  thus causing bleeding often related to vitamin K
  deficiency
• Hemophilias
• Genetic sex-linked conditions resulting in the
  inability to clot correctly bleeding is often
  caused by normal activity
• Different kinds associated with deficiencies in
  specific factors

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Blood Groups

• People have different blood types because the
  RBCs have specific glycoproteins associated with
  the plasma membranes
• If the glycoproteins of an RBC are seen as
  foreign by the body, the cells may be
  agglutinated (clumped together)
• There are 30 varieties of naturally occurring
  RBC antigens that are common in humans
• Approximately 100 others are familial
• These are used to put everyones blood into blood
  groups such as ABO and Rh

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ABO Blood Groups

• Based on the presence or absence of the
  agglutinogens A and B
• Their presence or absence gives rise to A, B, AB
  and O blood
• O which means neither is present is the most
  common blood type
• Preformed antibodies called agglutinins will form
  against those antigens not present
• A person with type O blood will have both anti-A
  and anti-B antibodies

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Rh Blood Groups

• There are at least 8 different types of
  agglutinogens called Rh factors
• Only C, D, and E are common
• 85 of Americans are positive for Rh factors
• Anti-Rh antibodies do not form spontaneously, but
  will form if a Rh- person receives Rh blood
• This can also occur in Rh- women pregnant with
  Rh babies

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The Heart

• Is about the size of a fist and generally weighs
  250-350 grams
• Is located more centrally in the chest between
  the lungs above the diaphragm. The sternum sits
  in front of the heart.

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The Cardiovascular System (cont

• The Heart
• Covered by the pericardium.
• Has two sides with two chambers.
• Blood flows through the heart in one direction.
• Valves control the blood flow.
• The cardiac conduction system controls the
  electrical impulses that cause the heart to
  contract.

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Layers of the Heart Wall

• The heart wall is composed of 3 layers
• Epicardium the visceral layer of the serous
  pericardium
• Often becomes fatty in older people
• Myocardium the contracting layer of the heart
  which is composed mainly of cardiac muscle
• Endocardium endothelium cells that line the
  inner myocardial surfaces (chambers of the heart
  and valves)

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Chambers

• The heart has 4 chambers
• 2 superior atria
• 2 inferior ventricle

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Atria

• The atria are receiving chambers for blood
  returning to the heart
• Relatively small, thin-walled chambers and
  responsible for very little pumping (blood moves
  from atria to ventricle)
• Blood enters the R. atrium via
• Superior vena cava returns blood from areas
  superior to the diaphragm
• Inferior vena cava returns blood from below the
  diaphragm
• Coronary sinus collects blood draining from the
  myocardium
• Blood enters the L. atrium via 4 veins from the
  lungs

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Ventricles

• Make up the bulk of the heart
• These are the discharging chambers. When the
  ventricles contract, blood is propelled out of
  the heart.
• The R. ventricle pumps blood to the pulmonary
  trunk which sends blood to the lungs where gas
  exchange occurs
• The L. ventricle ejects blood into the aorta
  which sends blood out to the body

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Path of blood through the heart
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Pathway of Blood

• The heart consists of two circuits
• Pulmonary circuit the blood vessels that carry
  blood to and from the heart
• The pump is the right side of the heart
• Systemic circuit the blood vessels that carry
  blood to and from the body
• The pump is the left side of the heart
• Deoxygenated blood returning from the body will
  enter the R. atrium, enters the R. ventricle
  where it pumps to the lungs via the pulmonary
  arteries. Oxygenated blood then returns to the
  L. atrium via the pulmonary veins, enters the L.
  ventricle where it pumps to the body via the
  aorta.

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The Cardiovascular System (cont.)

• Circulation
• Coronary circulation the circulation of blood
  within the heart.
• Pulmonary circulation the flow of blood between
  the heart and lungs.
• Systemic circulation the flow of blood between
  the heart and the cells of the body.

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The Heartbeat

• Each heartbeat is called a cardiac cycle.
• When the heart beats, the two atria contract
  together, then the two ventricles contract then
  the whole heart relaxes.
• Systole is the contraction of heart chambers
  diastole is their relaxation.
• The heart sounds, lub-dup, are due to the closing
  of the atrioventricular valves, followed by the
  closing of the semilunar valves.

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Heart Valves

• Blood flows through the heart in one direction
  enforced by 4 valves
• 2 atrioventricular (AV) valves located at each
  atrial-ventricular junction
• R. AV valve (tricuspid valve)
• L. AV valve (bicuspid or mitral valve)
• 2 semilunar (SL) valves
• Aortic SL valve located at junction between L.
  ventricle and aorta
• Pulmonary SL valve located at junction between R.
  ventricle and pulmonary trunk

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Heart Sounds

• During each heartbeat, 2 sounds can be
  distinguished
• Described as lub-dup, pause, lub-dup, pause, etc.
• Sounds associated with closing of heart valves
• 1st sound AV valves close
• 2nd sound SL valves close (generally do not
  close at the same time making this sound less
  defined)

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Heart Sound Link

• http//www.med.ucla.edu/wilkes/intro.html
• Normal Sounds
• Murmurs
• Wheezing
• Crackles

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Disorders of the Heart

• Asystole situation in which the heart fails to
  contract
• Commotion cordis situation in which a
  relatively mild blow to the chest causes heart
  failure and sudden death
• Occurs during a vulnerable time during the heart
  repolarizing
• Endocarditis inflammation of the endocardium
  often caused by bacterial infection

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Disorders of the Heart

• Heart palpitation a heartbeat that is unusually
  strong, fast, or irregular
• Can be caused by drugs, emotional pressures or
  heart disorders
• Hypertrophic cardiomyopathy (HCM) cardiac
  muscle cells enlarge, thickening the heart wall.
  The heart pumps well, but doesnt relax well
  during diastole when the heart is filling
• Leading cause of death among young athletes

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Disorders of the Heart

• Mitral valve prolapse the mitral valve does not
  close properly, allowing blood regurgitation.
• Affects up to 10 of the population often seen
  in young women may be genetic
• Often treated with valve replacement
• Myocarditis inflammation of the myocardium may
  weaken the heart and its ability to pump
• Often caused by untreated strep infection

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Diseases and Disorders (cont.)

• Diseases and Disorders
• Hypertension.
• Stroke.
• Arteriosclerosis.
• Aneurysm.
• Coronary artery disease (CAD).
• Heart attack (Myocardial Infarction)
• Congestive heart failure (CHF).
• Anemia, hemophilia, and leukemia.

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BLOOD VESSELS
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ARTERIES

• FUNCTION CARRY BLOOD AWAY FROM THE HEART
• CHARACTERISTICS
• VERY THICK, MUSCULAR WALLS (WHY).
• VERY HIGH BLOOD PRESSURE
• CARRIES OXYGENATED BLOOD
• EXAMPLES CORONARY, AORTA, CAROTID, FEMORAL

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ATHEROSCLEROSIS
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ARTERIES
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CORONARY ARTERIES
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ARTERIES IN BRAIN
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VEINS

• FUNCTION AFTER BLOOD MOVES THROUGH THE ARTERIES
  IT ENTERS BLOOD VESSELS CALLED VEINS, WHICH CARRY
  BLOOD BACK TO THE HEART.
• CHARACTERISTICS
• THINNER WALLS WITH LESS MUSCLE
• HAVE VALVES
• CARRIES DEOXYGENATED BLOOD (1 EXCEPTION)
• EXAMPLES VENA CAVA, JUGULAR,
• LOCATION NEAR MUSCLES

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VEINS
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VEINS VS. ARTERIES
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Vein Valves

• Allows flow of blood in only ONE DIRECTION

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VEINS
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SPIDER VEINS
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RETICULAR VEINS
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VERICOSE VEINS
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VERICOSE VEINS
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CAPILLARIES

• FUNCTION WHERE MATERIAL (OXYGEN, NUTRIENTS,
  CARBON DIOXIDE, ENERGY) IS EXCHANGED BETWEEN
  BLOOD AND CELLS
• CHARACTERISTICS
• VERY SMALL
• WALLS ARE ONLY ONE CELL THICK
• DIFFUSION TAKES PLACE
• MOST ABUNDANT
• FOUND NEAR MUSCLE CELLS, ORGANS, ETC.

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CAPILLARIES
http//www.innerbody.com/htm/body.html