Blood and the Cardiovascular System

1
Blood and the Cardiovascular System
2
Blood Path Through the Body

• Blood is pumped throughout the body by the heart
• Travels from the heart through arteries, then
  through capillaries where oxygen and nutrients
  diffuse into surrounding tissue and carbon
  dioxide and waste diffuse from the tissue into
  the blood
• Oxygen deficient blood travels back to the heart
  through veins

3
Blood Composition and Function

• Blood is a specialized form of connective tissue
  in which living blood cells, the formed elements,
  are suspended by nonliving matrix called plasma.
• Blood spun in centrifuge will have the heavier
  formed elements at the bottom and the less dense
  plasma at the top
• The reddish mass at the bottom layer would be
  primarily erythrocytes (red blood cells)
  Erythrocytes constitute about 45 of total blood
  volume
• There is a white thin layer called the buffy coat
  that is primarily composed of leukocytes (white
  blood cells) that act in various ways to protect
  the body and platelets which are cell fragments
  that help the body stop bleeding (All of these
  constitute less than 1 of blood volume)
• Plasma makes up the remaining 55 of blood

4
Blood Composition and Function
5
Blood Composition and Function
6
Blood Composition and Function

• Blood accounts for about 8 of body weight with a
  average volume of 5-6 L in adult males and 4-5 L
  in adult females
• Color varies from scarlet red (oxygen rich) to
  dark red (oxygen poor)
• Blood is more dense than water and about five
  times more viscous
• Blood has a pH that runs from 7.35 to 7.45 and a
  temperature of about 38 degrees Celsius or 100
  degrees Fahrenheit, slightly higher than body
  temperature

7
Blood Composition and Function

• Functions of blood include
• Distribution
• Oxygen from lungs and nutrients from the
  digestive tract
• Transporting waste products from cells to
  elimination sites
• Transport hormones from the endocrine organs to
  their target organs
• Regulation
• Maintain appropriate body temperature by
  absorbing and distributing heat throughout the
  body and to the skin to encourage heat loss
• Maintain normal pH in body tissues
• Maintain adequate fluid volume in the circulatory
  system
• Protection
• Prevent blood loss with platelets and blood
  proteins initiating clot formation
• Prevent infection with antibodies, complement
  proteins and white blood cells

8
Blood Plasma

• Although it is mostly water (90) it does contain
  over 100 dissolved solutes including nutrients,
  gases, hormones, wastes, ions, and proteins
• Plasma proteins which account for 8 of plasma
  weight are the most abundant plasma solute and
  they serve a variety of functions
• Albumin accounts for 60 of plasma protein that
  helps carry certain molecules through
  circulation, act as a blood buffer, and is a
  major contributor to osmotic pressure (the
  pressure that helps keep water in the blood
  stream)

9
Formed Elements General

• The formed elements of blood are erythrocytes,
  leukocytes, and platelets
• Erythrocytes have no nucleus or organelles
• Platelets are fragments of cells
• Most of the formed elements survive in the
  bloodstream for only a few days
• Most blood cells do not divide but instead are
  continuously renewed by division of cells in bone
  marrow

10
(No Transcript)
11
Formed Elements Erythrocytes

• Small in diameter that appear as a flattened disc
  with depressed center
• Virtually a bag of hemoglobin, the protein that
  functions for gas transport of oxygen and about
  20 of carbon dioxide released by cells
• The erythrocyte structure contributes to its
  function by
• Small size and biconcave shape provide huge
  surface area relative to volume to help with gas
  exchange
• Discounting water content the erythrocyte is over
  97 hemoglobin
• Because erythrocytes do not contain any
  mitochondria and generate ATP by anaerobic
  mechanisms they do not consume any oxygen that
  they are transporting

12
Formed Elements Erythrocytes

• Hemoglobin, the protein that makes red blood
  cells red, binds easily and reversibly with
  oxygen
• Hemoglobin is made of the protein globin and
  bound to the red pigment heme. Each heme group
  (which there are four) bears an atom of iron at
  its center which oxygen binds to therefore every
  hemoglobin molecule can carry four molecules of
  oxygen
• Some carbon dioxide can bind to a deoxygenated
  hemoglobin molecule but it binds to the amino
  acid part of the hemoglobin molecule not the iron

13
(No Transcript)
14
Formed Elements Erythrocyte Production

• Blood cell formation is known as hematopoiesis
  which occurs in the red bone marrow
• On average red bone marrow turns out 100 billion
  new blood cells every day
• All formed elements arise from the same type of
  stem cell the pleuripotent hemocytoblast
• However their maturation paths differ and once a
  cell is committed to a specific blood cell
  pathway it cannot change
• This commitment is signaled by the appearance of
  membrane surface receptors that respond to
  specific hormones or growth factors that push the
  cell toward further specialization

15
(No Transcript)
16
Hormonal Control of Erythropoiesis

• It is important to have just the right amount of
  red blood cells too few leads to tissue hypoxia
  (lack oxygen) and too many leads to very viscous
  blood
• Under normal conditions a small amount of the
  hormone erythropoietin circulates through the
  blood maintaining red cell production to replace
  red blood cell loss
• When certain kidney cells become hypoxic they
  increase the release of this hormone to increase
  blood cell production
• Factors that may cause this to happen are
• Reduced number of red blood cells due to
  hemorrahage
• Insufficient hemoglobin per RBC (maybe iron
  deficiency)
• Reduced availability of oxygen such as in high
  altitudes or during pneumonia

17
Erythrocyte Disorders

• Most erythrocyte disorders can be classified as
  anemias (abnormally low oxygen carrying capacity)
  or polycythemias(abnormally high erythrocyte
  numbers)
• Common causes of anemias are
• Insufficient number of red blood cells example
  would be a result of hemorrhage
• Low hemoglobin content such as those with iron
  deficiencies
• Production of abnormal hemoglobin. An example is
  sickle cell anemia which is the result of a
  change in one of the 287 amino acids that make up
  hemoglobin which cause it to change shape under
  low oxygen conditions making the red blood cells
  stiff and likely to rupture

18
Leukocytes (White Blood Cells)

• Only formed elements that are complete cells with
  nuclei and organelles.
• They account for less than 1 of total blood
  volume
• On average there are 4800-10,800 WBCs/microliter
  of blood
• They are crucial to our defense against disease
  and unlike red blood cells, they are not confined
  to our blood stream
• They are grouped into two major categories the
  granulocytes and agranulocytes

19
Granulocytes

• These are roughly spherical in shape and are
  larger and much shorter lived then erythrocytes
• Functionally all granulocytes are phagocytes to a
  greater or lesser degree
• The types of granulocytes are
• Neutrophils-the most numerous leukocyte they
  account for 50-70 of leukocyte population they
  are active phagocytes especially against bacteria
• Eosinophils- they account for 2-4 of leukocyte
  population they lead the fight against parasitic
  worms
• Basophils-these are the rarest leukocyte and
  account for only 0.5-1 of population they
  release histamine which acts as a vasodilator and
  attract other white blood cells to an area

20
Agranulocytes

• The two types of agranulocytes are as follows
• Lymphocytes-these account for 25 of the
  leukocyte population these play a crucial part
  in immunity against things like viruses and give
  rise to plasma cells that produce antibodies
• Monocytes-these account for 3-8 of leukocyte
  population they are very active macrophages and
  are crucial in defense against viruses, certain
  intracellular bacteria parasites, and chronic
  infections

21
(No Transcript)
22
(No Transcript)
23
Platelets

• Platelets are cytoplasmic fragments of
  extraordinarily large cells called megakaryocytes
• Platelets are essential to blood clotting process
  when blood vessels are damaged
• They stick to the damaged site and form a
  temporary plug that helps seal the break

24
Hemostasis

• Hemostasis is the steps involved to stop bleeding
  when a blood vessel breaks
• The hemostasis response is fast, localized, and
  carefully controlled
• Three rapid steps occur during hemostasis
• Vascular spasms- chemicals released by damaged
  epithelial cells cause blood vessels to become
  constricted to reduce blood loss
• Platelet plug formation- platelets begin to
  adhere to exposed collagen fibers and in turn the
  platelets release chemicals that attract more
  platelets together
• Coagulation-blood is transformed from a liquid
  into a gel when signaled by chemicals in the blood

25
Disorders of Hemostasis

• Thromboembolic conditions include disorders that
  cause undesirable clot formation
• Thrombus- a clot that develops and persists in an
  unbroken blood vessel
• Embolus- a blood clot that floats freely in the
  blood stream
• Embolism- a blood clot that passes through a
  blood vessel that is too narrow for it to pass
  and eventually blocks that blood vessel
• Hemophilia refers to a genetic condition where
  the body lacks the ability to create many of the
  clot causing chemicals so blood does not clot
  easily

26
Blood Types

• Humans have different blood types
• These blood types are the result of very specific
  glycoproteins (antigens) on the external surface
  of an individuals red blood cells
• If a persons body recognizes a red blood cell as
  foreign it will cause agglutination to occur
  (clumping together of foreign cells)
• This occurs when a foreign antigen is present in
  a persons body
• The presence or lack of presence has allowed
  people to be classified into several different
  blood type groups
• ABO groups
• Rh blood group

27
Blood Types by Population
  Caucasians African American Hispanic Asian
O 37 47 53 39
O - 8 4 4 1
A 33 24 29 27
A - 7 2 2 0.5
B 9 18 9 25
B - 2 1 1 0.4
AB 3 4 2 7
AB - 1 0.3 0.2 0.1
28
(No Transcript)
29
Cardiovascular System

• The Heart

30
Size, Location, and Orientation

• The Heart is basically the pump that moves blood
  throughout the body to transport important body
  chemicals and help remove wastes
• 2/3 of the heart is located to the left of the
  midsternal line and the balance projects to the
  left
• It is roughly the size of the fist and has a mass
  between 250-350 grams (less than a pound)
• The bottom apex points inferiorly toward your
  left hip while its broad flat base points toward
  your right shoulder

31
(No Transcript)
32
Coverings and Layers of the Heart

• The heart is enclosed in a double walled sac
  called the pericardium
• The heart wall is composed of three layers.
  These include
• The superficial epicardium that is often
  infiltrated with fat
• The middle layer called the myocardium that is
  composed mainly of cardiac muscle arranged in
  circular or spiral bundles
• The inner layer is known as the endocardium

33
(No Transcript)
34
Chambers and Greater Vessels of the Heart

• The heart contains four chambers-two superior
  atria (right and left atrium) and two inferior
  ventricles (right and left ventricle)
• The internal partition that separates the two is
  called the interatrial septum and
  interventricular septum
• Functionally the atria are receiving chambers for
  blood returning from circulation and because they
  only push blood into the inferior ventricles they
  are relatively small, thin walled chambers that
  contribute little to the propulsive pumping
  action of the heart

35
Chambers and Greater Vessels of the Heart

• The right atrium receives blood from three veins
• Superior vena cava returning blood from regions
  superior to the diaphragm
• Inferior vena cava returning blood from regions
  inferior to the diaphragm
• Coronary sinus which collects blood draining from
  the myocardium
• The left atrium receives blood from four
  pulmonary veins bringing blood from the lungs to
  the heart
• The ventricles make up most of the volume of the
  heart
• They are the discharging chambers or actual pumps
  of the heart as they pump blood to the lungs and
  to the rest of the body
• The right ventricle pumps blood into the
  pulmonary trunk to be sent to the lungs to
  undergo gas exchange while the left ventricle
  pumps blood through the aorta to the body

36
(No Transcript)
37
(No Transcript)
38
(No Transcript)
39
Pathway of Blood Through the Heart

• The heart is a two pump system operating side by
  side each serving a separate blood circuit
• The blood vessels that carry blood to and from
  the lungs form the pulmonary circuit
• The blood vessels that carry functional blood to
  and from all body tissues constitute the systemic
  circuit
• The right side of the heart is the pulmonary
  circuit pump
• The left side of the heart is the systemic
  circuit

40
Pathway of Blood Through the Heart

• Blood returning from the body tissues low in
  oxygen and rich in carbon dioxide is received
  into the right atrium where it moves to the right
  ventricle
• The right ventricle pumps the blood through the
  pulmonary trunk to the lungs for gas exchange
• The oxygenated blood then travels from the lungs
  to the left atrium through the pulmonary veins
• The left ventricle then pumps the blood to the
  tissue of the body
• Although equal volumes of blood is pumped through
  the pulmonary and systemic circuit at any moment
  the left ventricle must pump blood to the entire
  body where as the right side is only pumping the
  blood to the lungs. The left ventricle works
  much harder in doing so and therefore has a much
  thicker wall

41
(No Transcript)
42
Coronary Circulation

• Coronary Circulation is the functional blood
  supply of the heart and is the shortest
  circulation in the body
• The arterial supply of the coronary circulation
  is the right and left coronary arteries
• These arteries provide an intermittent pulsating
  blood flow to the myocardium. They deliver blood
  when the heart is relaxed but are relatively
  ineffective during ventricular contractions
• Although the heart is about 1/200th of the bodys
  weight it requires about 1/20th the bodys blood
  supply
• After passing through the capillary beds in the
  myocardium the blood empties into the cardiac
  veins and runs toward the coronary sinus where
  blood empties into the right atrium

43
Coronary Circulation Disorders

• Prolonged blockage of the coronary arteries can
  lead to a lack of oxygen delivery to the
  myocardium
• This can cause an event known as myocardial
  infarction (heart attack)
• Adult cardiac muscle is essential amitotic (do
  not divide) most areas of cell death lead to be
  repaired with noncontractile scar tissue

44
Heart Valves

• Blood flows through the heart in one direction
  from atria to ventricles and out the great
  arteries leaving the superior aspect of the
  heart. This is accomplished by four valves
• There are two atrioventricular valves that
  prevent backflow into the atria when the
  ventricles contract
• The right atrioventricular valve is composed of
  three flexible cusps so it is called the
  triscupid valve
• The left atrioventricular valve is composed of
  two flaps so it is called the biscupid valve aka
  (mitral valve)
• Attached to each atrioventricular valve is tiny
  white collagen chords called chordae tendinae
• When the heart relaxes the atrioventricular
  valves are relaxed and remain open. When the
  ventricles contract intraventricular pressure
  rises causing the atrioventricular valves to close

45
Heart Valves

• The semilunar valves (aortic and pulmonary) guard
  the bases of the large arteries issuing from the
  ventricles to prevent backflow into the
  associated valves
• When the ventricles contract, intraventricular
  pressure increases cause the valves to be forced
  open. They close when the pressure drops.
• When valves do not close or open properly the
  heart can still function but must work much
  harder due to the backflow or constriction of
  blood flow causing the heart to be weakened

46
Heart Animations

• http//bcs.whfreeman.com/thelifewire/content/chp49
  /49020.html
• http//www.youtube.com/watch?vy5maHDAkzUs
• http//www.youtube.com/watch?vM8HYmaDpWpE