Anatomy

1
Chapter 19

• Anatomy Physiology
• Fifth Edition
• Seeley/Stephens/Tate
• (c) The McGraw-Hill Companies, Inc.

2
Blood

• Introduction
• Blood has been the source of mysteries for
  thousands of years.
• Blood is a type of C.T. consisting of cells and
  liquid.
• Blood is circulated by pumping action of the
  heart, the valves in blood vessels and by the
  contracting action of calf muscles.
• The total volume of an adult female is 4 5 L,
  while that an adult is 5 6 L.
• Blood constitutes about 8 of the total body
  weight of the human and the components may be
  divided with centrifugation.
• Study Fig. 19.1 carefully.

3
(No Transcript)
4

• The Functions of Blood
• At least 5 major functions of blood have been
  identified( I have broken down the functions to
  5, rather than 3 as shown in the text.)
• Transportation for gases, nutrients, hormone,
  vitamins, and metabolic wastes.
• Regulation of the pH, electrolytes and
  composition of interstitial fluids throughout the
  body.
• Homeothermic keeping the organism at constant
  temperature.
• Protection of damage sites with blood clots.
• Immunogenic defense against toxins and
  pathogens.

5

• Blood Collection and Analysis
• Collection of human blood is usually performed
  from a superficial vein via venipuncture or from
  the finger tip or sole.
• Only when needed an arterial puncture may be
  performed.
• The temperature of blood is about 38C and is
  slightly higher than that of the body
  temperature.
• Having a large quantity of proteins in plasma
  (7g/100ml) and corpuscles, bloods viscosity is
  more than five times higher than that of water.
• The pH of blood is about 7.4.

6

• Plasma (see Table 19.1)
• The plasma volume remains relatively consistent.
• Differences between plasma and interstitial
  fluids
• The composition of plasma and that of
  interstitial fluid is about the same, but the
  former has more proteins and dissolved gases.
• Plasma Proteins
• 7g/100ml of plasma
• Albumin 58 of plasma proteins. Osmotic balance.
• Globulin 38. Immunoglobulins, lipoproteins and
  transport proteins antibodies and thyroid
  hormone-binding proteins.
• Fibrinogen 4. Can form large fibrins to form
  blood clot.
• 50 of plasma proteins are produced by plasma
  cells.
• The other substances in plasma
• In addition of dissolved proteins, plasma
  contains ions, nutrients, waste products, gases
  and regulatory substances.

7

• Formed Elements
• The hematocrit refers to the percentage of blood
  cells ( in practice the formed elements). This
  number is obtained by centrifuging the blood held
  in a thin glass tube at a high speed. The formed
  elements will settle down to the bottom and its
  ratio to the total volume is the hematocrit.
• The hematocrit is about 46 for male and about
  42 for females.
• Red blood cells 99.9 of the formed elements
  in volume or 4.2 6.2 million/mm³. Erythrocytes
  are enucleated and have little organelles.
• White blood cells (leukocytes) have nuclei
• Granulocytes are neutrophils, eosinophils and
  basophils.
• Agranulocytes are lymphocytes, monocytes.
• Platelets enucleated and have little
  organelles.

8
(No Transcript)
9

• Production of Formed Elements Hemopoiesis or
  hematopoiesis
• The major production sites of the formed elements
  shift
• The first 8 weeks they start at the embryonic
  yolk sac and they begin to settle in the liver,
  spleen, thymus, and bone marrow. They become stem
  cells.
• Form the 8th week to 5th month in the liver and
  spleen are the primary sites of hemopoiesis.
• No nucleus or organelles, thus only glycolytic
  enzymes to form energy by glycolysis.
• Carbonic anhydrase responsible for conversion
  and transportation carbon dioxide.
• Phospholipids and membrane proteins and others
  etc.

10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14

• Erythrocytes are
• 99.9 in volume of the formed elements.
• 5.4 million cells/ one microliter (ul or mm³) of
  blood for a man.
• 4.8 million cells/ one microliter (ul or mm³) for
  a woman.
• 260 million RBC/drop of blood.
• 25 trillion RBCs in the blood of an adult 1/3
  of all the cells in the human body. (75 trillion
  cells)
• The difference in the hematocrit mention earlier,
  I.e. 46 to men and 42 to women, arises from the
  fact that androgens in men stimulate
  erythropoiesis, while estrogens in women are
  inhibitory.
• The ratio of white cells to red cells is 1 to
  1000.
• The hematocrit vs disease anemia and
  polycythemia.

15

• Structure of RBCs
• Uniquely biconcaved and flexible (Fig 19.3), have
  excellent exchange of gases between the cells and
  the environment. Contrary to a sphere, the RBC
  has the maximum surface to volume ratio.
• The diameter is 7.5 microns and the thickness
  varies at the edge (thick, 1.5 microns) and the
  center (thinner, 1 micron) making it possible to
  tumble and bend in tissue capillaries.

16

• The primary function of RBCs is performed by
  hemoglobin.
• 33 of RBC is hemoglobin, Hb, an oxygen and CO2
  carrying protein.
• Each Hb consist of two pairs of subunits (alpha
  and beta) and each subunit has an oxygen binding
  heme. (Fig. 19.4)
• Since the oxygen binding to heme is reversible,
  the number of oxygen bound to heme depends upon
  the amount of oxygen is in the environment of Hb.
• Thus, in the lungs, where oxygen pressure is
  high, Hb binds oxygen and carries the gas to the
  tissues where the oxygen pressure is low.

17
(No Transcript)
18

• Binding of CO2 to Hb is not at the heme, but is
  at the alpha amino group of the N-terminal ends
  of four subunits.
• CO2 binding is essentially opposite to that of
  oxygen, but again follows the amount of CO2 in
  plasma.
• (O2 - 95 w/Hb, 5 dissolved)
• (CO - 7 dissolved, 23 w/ Hb, 70 as
  bicarbonate)
• The circulation of CO2 also relies on the
  chemically dissolved form of CO2, i.e.,
  bicarbonate. This process is facilitated by
  carbonic anhydrase.
• Thus carbon dioxide may be transported as
  carboamino hemoglobin, dissolved bicarbonate and
  free carbon dioxide.

19

• Life Span and Circulation
• Complete circulation of an erythrocyte in a body
  usually takes less than a minute.
• During this period, especially while negotiating
  through tissue capillaries of less than several
  microns of diameter, pulsating motion of blood
  flow severely stresses the erythrocytes.
• In addition, despite the presence of complex
  protective mechanisms, carrying of oxygen would
  provide ample opportunities to cause oxidative
  damages to the contents of the cells.
• As a consequence, the life span of a RBC is about
  120 days.
• Since the hematocrit of a normal person is
  relatively consistent, the loss of erythrocytes
  is compensated with continuous erythropoiesis.
• Old or damaged erythrocytes are usually
  phagocytically broken down in the liver, spleen
  and bone marrow.
• Recycled Hb, when in small quantities, its path
  is through the kidneys and into the urine. If
  this level goes up, there will be discoloration
  of the urine.(yellowish ---- iron)

20
(No Transcript)
21

• Recycling of RBC/hemoglobin Components
• Macrophages in the spleen, liver, and other
  lymphatic tissues phagocytically engulf
  erythrocytes.
• Globular proteins are broken down to amino acids
  for resumption.
• Heme is separated from its iron and becomes
  biliverdin (green) then to bilirubin to be
  absorbed in the liver, there conjugated and then
  excreted in bile from the intestines. A build up
  of bilirubin in the circulation and intestinal
  spaces is known as jaundice.
• Iron may be stored with the plasma protein,
  transferrin and recycled.
• Erythropoiesis is regulated with erythropoetin
  from the kidneys, which appears in the plasma
  when peripheral tissues are exposed to low oxygen
  concentration, hypoxia.

22
(No Transcript)
23

• White Blood Cells leukocytes
• They are different from RBC because of the
  presence of nuclei and the lack of hemoglobin
  thus the transparent or white appearance.
• They are loosely divided into (Table 19.2)
• Granulocytes Neutrophils, eosinophils, basophils
• Agranulocytes monocytes, lymphocytes
• There are as many as 6-8,000 leukocytes in 1
  microliter of blood, but most of the leukocytes
  are found on peripheral tissues.

24

• WBC Movement
• WBC are capable of amoeboid movement.
• Thus, they can migrate out of the epithelia of
  capillary walls, diapedesis.
• Positive chemotaxis leads them to the troubled
  spots. There they are phagocytotic.
• General Functions
• General defense neutrophils, eosinophils,
  basophils and monocytes
• Specific immunity lymphocytes
• Neutrophils polymorphonuclear
• Live in the circulatory system for only 10-12
  hours, then move into tissues, where they live up
  to 1-2 days.
• Phagocytic and secrete lysozymes to digest
  bacteria and others.

25

• Eosinophils reduce inflammation and parasitic
  reaction.
• Basophils releases histamines, which promotes
  inflammation also release heparin, which inhibits
  blood clotting.
• In new born and young children, both have mostly
  red bone marrow.
• In adults, red bone marrow found in the skull,
  fibs, sternum, vertebrae, pelvis, proximal femur
  and proximal humorous.
• Observe the hematopoiesis of stem cell in Fig.
  19.2.
• Stem cell are the origin of all formed elements.
• Note the types of blast cells and the final cell
  types.
• Monocytes live 2-3 days in circulation and
  migrate in the tissues as macrophages, which
  phagocytose foreign bodies. An increased number
  of monocytes is an indication of an infection.

26

• Lymphocytes
• They are about the size of an RBC and they
  contain a nucleus. Most of the lymphocytes dwell
  in the lymphatic system. There are three types
• T-cells attack foreign bodies.
• B-cells differentiate into plasma cells, which
  secrete antibodies.
• Natural Killer cells (NK cells) destroys the
  bodies own abnormal cells.

27

• Platelets
• Megakaryocytes in bone marrow, which release
  their fragments into circulation, then called
  platelets.
• Platelets have no nuclei.
• Participate in blood clotting.
• Platelets survive about 10-12 days in circulation
  and are about 150,000 300,000/ul
• Thrombocytopenia is a loss of platelets and is a
  sign of bleeding etc..
• Thrombocytosis is excess platelets and is a sign
  of infection.

28

• Hemostasis arrest of bleeding.
• Prevents loss of blood in three phases.
• The vascular phase immediate temporary closure
  of a blood vessel by constriction of vascular
  smooth muscles.
• The platelet phase formation of a platelet plug
  by platelet adhesion and aggregation (Fig 19.9).
  Platelets bind to collagen in damaged tissues.
  Platelets are adhered and form a plug.
• The coagulation phase for a large blood clot
  formation by the network of fibrin from
  fibrinogen. A large number of steps involving
  many factors are required, some of which require
  thrombin and Ca.

29
(No Transcript)
30

• The clotting process
• Clotting is the phenomenon where blood cells are
  trapped in the framework of fibers.
• The clotting process requires Ca and 11
  different plasma proteins, mostly enzymes.
• The process goes through 3-stages
• Activation of prothrombinase by either the
  extrinsic or intrinsic pathway.
• Prothormbinase converts prothrombin to thrombin.
• Thrombin converts fibrinogen to fibrin.
• Extrinsic pathway the process is triggered by a
  tissue factor of damaged endothelial cells, the
  other enzymes are successively activated to
  complete the clotting process- a cascade. The
  process is fast and takes only 15 seconds.
• Intrinsic pathway starts with the activation of
  factor XII by contacting the damaged blood
  vessels and is a slower process.

31
(No Transcript)
32

• Clot retraction am Removal
• The platelets begin to contract clot
  retraction.
• During the repair process of tissue, the clot
  gradually dissolves fibrinolysis.
• This process draws a lot of attention because
  dissolving clots in heart attack or stroke
  patients is clinically important.
• To dissolve a clot
• Activated plasminogen by tissue plasminogen
  activator (t-PA) ? plasmin is produced ? plasmin
  digest the fibrin strands to dissolve the clot.

33
(No Transcript)
34

• Blood tests and RBCs (review)
• Blood types
• Genetically determined RBC antigens
  (glycoproteins) rest on the surface of the
  membrane.
• There are at least 50 different kinds of antigens
  on the surface of an RBC.
• Their antibodies are found in plasma.
• One set of important antigens are A and B, typed
  ABO. Although A/B antibodies are not found in the
  blood until about 2 months after birth. (Fig
  19.12)

35

• Blood Type Surface-antigen US pop
  In plasma antibodies
• A B
  A B
• TYPE A -
  40 -
  
• TYPE B -
  10
  -
• TYPE AB
  4 -
  -
• TYPE O - -
  46
  
• Rh D
• Blood donor and Recipient
• Blood may be received from the subject of the
  same blood type, but not from the other type,
  except one with subject with type O.
• Type O subject, who has no surface A/B antigen,
  has been considered as a universal donor, since
  the donated RBC will not be coagulated.
• However, the antibodies in the plasma can
  interact with the surface antigens of the
  recipient and may induce minor reactions. Thus,
  the word universal donor is misleading.

36

• Another important antigen is the Rh factor.
  Rh-positive or Rh-negative. The Rh positive
  subjects have the D antigen on the surface of the
  erythrocytes. About 86 of the people in the US
  are RH positive.
• Hemolytic Disease of the Newborn (HDN)

37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
The End.