Chapter 17 Part 1 Blood)

Question 1

Blood

Answer 1

Life-sustanining transport vehicle of the Cardiovascular System

• Transport function
  
  • Devivering O2 and nutrients to body cells
  • Tranport metabolic waste to lungs and kidneys
  • Tranport hormones from endocrine organs to target organs
• Regulation Functions
  
  • Mantaining body temp by absorbing/distributing heat through skin and blood vessels
  • Mantaining normal pH using Buffers
  • Mantaining aqeute fluid volume in circuitory system (endocrine function mostly)
• Protection Functions
  
  • Preventing Blood Loss; protiens and platlets form clots
  • Preventing Infection: Immune componants are carried in the blood (antibodies, WBC’s and Compliment protiens)

Question 2

Composition of Blood

Answer 2

Only Fluid tissue in the body. Technically a type of Connective Tissue

• Matrix) Nonliving fluid called plamsa
• Cells) Living blood cells are called formed elements
  
  • Suspended in plasma
  • Include Erythocytes (red blood cells, RBC’s), Lukeocytes (white blood cells, WBC’s) and Platlets.
• Blood spun in a centrafuge
  
  • Eythrocytes will be on the bottom (~45% compisition)
    
    • Hematocrit) percent of blood volume that is RBC’s
    • (47%± 5% in males) (42% ± 5% in females)
  • WBC’s and platlets in Buffy Coat (<1% compisition)
    
    • middle layer
  • Plasma is on top (~55%)

Question 3

Physical Characteristics and Blood Volume

Answer 3

• Blood is sticky, opaque fluid with metalic taste
• Color Varries with O2 content
  
  • High O2) Scarlet, bright red
  • Low O2) Dark red color
• pH stays within 7.35-7.45
• Makes up about ~8% of total body wight
• Blood Volume
  
  • Males) 5-6 liters
  • Females) 4-5L

Question 4

Blood Plasma

Answer 4

• A Straw-colored sticky fluid
  
  • about 90% is water
• Composed of over 100 dissolved solutes
  
  • Nutrients, gases, hormones, wastes, protiens, inorganic ions.
  • Plasma protiens are most abundent solutes
• Plasma Protiens
  
  • Remain in the blood; not uptaken by cells
  • Produced mostly by liver
• Albumin: Maked up to 60% of plasma protiens
  
  • Functions as a carrier of other molecules, blood buffer (pH) and contributes to plasma osmotic pressure.

Question 5

Formed Elements

Answer 5

• Formed elements are RBCs, WBCs, and platelets
• Only WBCs are complete cells
  
  • RBCs have no nuclei or other organelles
  • Platelets are cell fragments
• Most formed elements survive in bloodstream only few days
• Most blood cells originate in bone marrow and do not divide

Question 6

Erythocytes (RBC’s)

Answer 6

• RBCs are small-diamater (7.5 nanometer) cells that trasnport gas
  
  • Cell is a biconcave disc shape, anuclete (no nucleus) and has essentally no organelles
• Hemoglobin (Hb) involved in gas transpoet
• Can be larger than some capillaries
• Plasma membrane protiens
  
  • Spectrin) Mantains biconcave shape of erythocyte but allows it to change shape to move through small spaces (capillaries)

Question 7

Hemoglobin Structure

Answer 7

Hemoglobin binds reversibly with O2

• Consists of red Heme pigment bound to Protien Globin
• Globin is composed of four polypeptife chains
  
  • Two alpla and two beta chains
• Heme pigment is bonded to each globin chain
  
  • gives blood red color
  • Each heme’sc central iron atom bonds one O2
• Each Hb molecule can transport four O2
• Each RBC contains 250 million HB molecules
• O2 Pathways
  
  • O2 loading in the lungs produces oxyhemoglobin (ruby red and oxignated
  • O2 unloading in tissues produces deoxyhemoglobin (dark red reduced O2)
  • CO2 loading in tissues (as waste) produces Carbaminohemoglobin
    
    • 20% of CO2 in blood binds to Hb

Question 8

Production of Erythrocytes

Answer 8

• Hematopoiesis) Formation of all blood cells.
  
  • Occurs in Red Bone Marrow
  • found in axial skeleton, girdles, and proximal epiphyses of humerus and femur.
• Hematopoietic Stem Cells (hemocytoblasts) stem cell that gives rise to all formed elements
• Erythropoiesis) proccess of RBC formation that takes about 15 days
  
  • Hematopoietic Stem Cell > Myeloid Stem Cell
  • Myeloid Stem Cell > Proethroblast (a commited stem cell)
  • Proethryoblast will eject its organelles and degrade its nucleus and becomes a mature erythocyte in about 2 dayys.

Question 9

Regulation and Requirments of Erythopoiesis

Answer 9

• Too few RBC’s leads to hypoxia
• Too many RBC’s increases blood visocisty
• >2 million RBC’s are made per second
• Blance between RBC production and destruction depends on Hormonal Controls and Dietary Requirments
• Hormonal Control
  
  • Ertyhropoietin (EPO) the hormone that stimulates formation of RBC’s
  • There is always a small ammount of EPO in the blood to mantain basal rate
  • Released by Kidneys in Response to Hypoxia
• Diatery Requirments
  
  • Needs amino acids, lipid, and carbs as well as iron from diet.
  • 65% of iron is found in hemoglobin and the restis found in the liver, spleen and bone marrow.
  • Free iron is toxic so it is bound with the proteins Ferritin, Hemosiderin, and
  • transfered in blood via the protein Transferrin.

Question 10

Causes of Hypoxia

Answer 10

• Hypoxia) there is not adquete oxygen levels avaible.
• Causes
  
  • Decreased RBC numbers die to hemmorage or increased destruction.
  • Insufficent hemoglobin per RBC (iron deficiency)
  • Reduced availability of O2 (altuide, lung problems such as pnemonia)

Question 11

Destruction of Erythocytes

Answer 11

• Lifepan is about 100-120 days. because RBC’s are anucleate they do not grow or divide.
• Old RBC’s
  
  • are fragile and Hb begins to degenerate
  • Get trapped in spleen where macrophages break down and engulf
• RBC Breakdown
  
  • Iron, Heme, and globin are seperated
  • Iron binds to ferritin or hemosiderin and is then stored for reude
  • Heme is degraded into bilribin (bile pigemt) and is secrteted into intestines. (urobilinogen > Sterocobilin)
  • Globin is metabolized into amino acids that are released into blood circulation

Question 12

Anemia

Answer 12

• Blood has abnormally low O2 carrying capacity that cannot support normal metabolism
  
  • Caused by Blood loss, Not enough RBC’s being produced, or too many RBC’s being destroyed.
• Not Enough RBC’s being produced
  
  • Iron-Deficiency Anemia) low iron intake or absorbtion
    
    • RBC’s produced are small and called microcytes
  • Pernicious Anemia) Stomach mucosa that produces intrnsic factor is destrpyed. Intrensic Factor produced vitaman B12 which helps RBC’s divide
    
    • RBC’s cannot devide resultng in larfe macroctyes.
  • Renal Anemia) lack of EPO
• To Many RBC’s destroyed. (premature lysis or gemolytic anemias)
  
  • Thalassemias) One globulin chain is missing/faulty. RBC’s are thin, delicate and defficent in hemoglobin
  • Sickle-Cell anemia) Contain hemoglobin S (mutated hemoglobin). One amino acid chain is wrong which results in mishapen RBC’s when O2 levels are low

Question 13

Polycythemia

Answer 13

• Abnormal excess of RBC’s
  
  • increases blood viscosity which causes sluggish flow
• Polycythemia Vera) Bone marrow cancer leading to excess RBC’s
• Secondary Polycyhtemia) caused by low O2 levels or increaded EPO

Question 14

Lukeocytes (WBC’s)

Answer 14

• Only Formed element with complete cell (nuclei and organelles)
• Make up <1% of blood volume
• Function to defend against desiese
  
  • Can leave capillaries via diapedesis
  • move through tissue spaces via amoeboid motion and positivr chemotaxis
• Lukeocytosis) Increase of WBC’s which is a response to infection
• Two major Catagories
  
  • Granulocytes: contain visible cytoplasmic granules (neutrophils, eosinophils, basophils)
  • Agranulocytes: do not contain visible cytoplasmic granules (lymphocytes, monocytes)
• “Never let monkeys eat bananas” is memonic for number in body

Question 15

Granulocytes

Answer 15

• Larger and shorter-loved than RBC’s. Lobed nuclei and phagocytic to some degree
• Neutrophils) Most numerous WBC’s
  
  • Contain hydrolytic enzymed or antomicrobial proteins.
  • Defensins) 3-6 lobes in the nucleus.
  • Very phagocytic- “Bacteria slayers”. Kill by injecting oxidizing substances (bleach or hyrrogen peroxide)
• Eosinophils) Bilobed nucleus
  
  • release enzymes to digest parasitic worms, role in allergies and asthma
• Basophils) Rarest WBC
  
  • Bilobed nucleus and large purplish cytoplamic granules
  • Gransules contain histamine; and inflamatory chemical that acts as a vasodilator to attract WBC’s to inflamed sites.
  • Functionally similar to mast cells.

Question 16

Agranulocytes

Answer 16

• Lack visible cytoplasmic granules
• Have spherical or kidney-shaped nuclei
• Two types: lymphocytes and monocytes

Question 17

Lymphocytes

Answer 17

• Second most numerous WBC
• Large, dark purple nuclei with thin rim of blue cytoplasm.
• Mostly found in lymphoid tissue
• Two types
  
  • T Lymphocytes (T cells) act agaisnt virus-infected cells and tumor cells
  • B Lymphocyies (B cells) give rise to plasma cells which produce antibodies

Question 18

Monoctyes

Answer 18

• Larges luekocutes, abundent pale-blue cytoplams
• Dark, U shaped nuclei
• Leave circulation and enter tissues to diffrentiate into macrophages.
  
  • Activly phagocytic
• Activate lympocytes to mount immune response.

Question 19

Production and Life span of Leukocytes

Answer 19

• Leukopoiesis) production of WBC’s
• All lukeocytes orginate from hemocytoblasts that branch into two pathways
  
  • Lymphoid Stem Cells) produce lympocytes
  • Myeloid Stem Cells) Produce all other leukocytes.
• Granulocyte Production
  
  • Myeloid Stem Cells > Myloblasts > Premyelocyte > Myellocye > Band cell > mature cell
  • Granuloctes are stored in bone marrow.
• Agranulocyte Production.
• Monocytes
  
  • Myeloid Stem cell> Monoblast > Premonocyte > Monocyte
  • Share common precusor (Myeloid Stem Cells) with nuertrophil
  • Live for sevreal months
• Lympocytes
  
  • Lymphoid Stem cell > T Lympocyte and B Lympcyte precusors
  • T Cell precusor travels to thymus
  • B Cells mature in the bone marrow
  • Lymophocytes live for a few hours - a few days.

Question 20

Leukocyte Disorders

Answer 20

• Overproduction of abnormal WBC’s) Lukemia
  
  • Acute) Quickley advancing) lukemia affects stem cells (children)
  • Chronic) Slowly advancing) Lukemia affects proliferation of later cell stages (older people)
  • Fatal without cancer tratment.
• Abnormally Low WBC count) Lukopenia
  
  • can be drig induced, particullary by anicencer drugs or glucocorticoids.

Question 21

Platelets

Answer 21

• Fragemnts of larger megakaryocytes
• Contain chemicals involved in clotting process
  
  • Form temporary platelet plug that helps seal breaks in blood vessels.
  • Kept inactive during circulation by chemicals lining blood vessels.
• Platlet formation is regulated by thrombiopoetin
  
  • Formed from megakaryoblast (Stage 1)
  • Stage IV megakaryocyte sends cytoplamisc projections into capilary which break off to become platlet fragments.
• Platlets age and degenrate in about 10 days.

Question 22

Hemostasis

Answer 22

• Fast Series of Reactions for stoppage of bleeding
  
  • reuires clotting factors and substances released by platlets

1. .Vascular Spasm) Vessel responds to injury with vasoconstriction. Triggerd by
   
   • Direct injury to vascular smooth muscle
   • Chamicals released by enthelial cells and platlets
   • Pain reflexes.
   • Reduces blood flow until other mechanisms kick in
2. Platlet Plug Formation) Platlets stick to collegen fibers exposed when vessel is damaged.
   
   • Positve Feeback) more platlets relaese more chemicalss triggering more platlets to come and clog
3. Coagulation) Blood Clotting reinfoces platlet plug
   
   • Blood transformed from liquid to gel via a seried of clotting factors
   • Occurs in three phases.

Question 23

Three Stages of Coagulation

Question 24

Restoring Blood Volume

Answer 24

• Body can compensate for only so much blood loss
  
  • Loss of 15-30% causes weakness and pallor
  • Loss of more than 30% can result in severe shock and death
• Volume must be replaced with a normal saline or multiple-electrolyte solution
  
  • mimics blood plasma
  • Replacment of volume does not replace RBC’s immediatly.

Question 25

Human Blood Groups

Answer 25

• RBC membranes bear many antigens
  
  • Antigens on RBC’s are there so defense cells can reconize blood cells as friendly
  • Any forgin antigens can trigger the immune reponse
• RBC antigens are reffered to as agglutinogens
  
  • they protmote agglutination (forgein blood cells are precived as invaders and may be aggluinated and destroyed)
• ABO and Rh blood groups cause major reactions

Question 26

ABO Blood Groups

Answer 26

• Type A blood
  
  • Has A agglutinogen
  • Has anti-B antibodies
• Type B
  
  • Has B agglunitogen
  • Has anti-A antibodies
• Type AB
  
  • has both A and B agglutinogens
  • has no antibodies
• Type O
  
  • has neither A nor B agglutinogens
  • Has anti-A and anti-B antibodies

Question 27

Rh Blood Groups

Answer 27

• There are 52 named Rh agglutinogens (Rh Factors)
  
  • C,D, and E are the most common
• Rh+ indicated presence of D antigen
• Those who are Rh- do not spontanesouly have anti-RH antibodies
  
  • Anti-RH antibodies form if Rh- individual is exposed to Rh+ blood

Question 28

Transfusions

Answer 28

• Type O is the universal donar
  
  • no A or B antigens
• Type AB is the universal recipient
  
  • No anti-A or anti-B antibodies.