Blood

Anatomy and Physiology II - Unit 1

List the functions of blood

Transport

• gases (O2 + CO2)

• metabolic waste products

• hormones

Regulation

• temperature → blood flow

• pH → bicarbonate

• fluid volume → body and interstitial tissues

Protection

• clotting to prevent blood loss upon acute damage

• immune system elements to fight infection → innate and adaptive

What is blood made of in simple terms?

• suspension of cells in a liquid

  • cell = erthyrocytes, leukocytes and platelets

  • liquid = plasma

Percent composition of blood

• separate out via centrifugation

  • Anti-coagulant added

    • upper layer plasma

      • 55% by volume '

      • contains 92% water, 7% protein, and 1% solutes

      • least dense

    • thin buffy coat of leukocytes + platelets on top

      • less than 1% of whole blood

    • thick red layer of erythrocytes on bottom

      • 45% of whole blood and most dense component

Why blood is a connective tissue

• progenitor cells derived from embryonic mesoderm

  • formed in red bone marrow

  • progenitor → early descendants of stem cells that cannot divide and reproduce indefinitely like stem cells

  • these cells became HSCs which then differentiate into various blood cells

• has cells, suspended in ECM (plasma) and can form fibers to aid in clotting

• leukocytes can migrate into collagenous connective tissues + epithelial cells

Describe the composition and function of plasma.

• involved in osmotic balance, protection, and transport of vitamins and minerals

• Albumin

  • made of 60% of plasma protein

  • made by liver

  • major colloidal osmotic agent in blood

  • binds/transports hydrophobic biomolecules

• Immunoglobulins

  • 18% of plasma protein

  • product of immune system cells in lymphoid organs

  • involved in humoral/adaptive immune response

• Fibrinogens

  • 4% of plasma proteins

  • made by liver

  • blood clotting proteins

• Hormone, fat-soluble vitamins, lipids and redox metal binding proteins

  • hormones: IGF-binding protein, thyroxine binding protein, transcortin

  • Vitamins: retinol binding protein, Vitamin D binding protein

  • Lipids: apolipoproteins

  • Redox metals: ceruloplasmin, transferrin

  • most made in liver

• Ions and Solutes

  • Ions

    • high in Na+, CI-, and Ca2+ relative to cytosol

    • major buffer is bicarbonate

    • other minerals in low concentration

  • Solutes

    • glucose

    • amino acids

    • waste products

    • hormones

    • lipids

Describe the structure, function and production of erythrocytes.

• 99%

• lack nucleus and mitochrondria

• biconcave

• hemoglobin

  • binds gases

    • high affinity for O2, NO, and CO at home

    • weak affinity for CO2, and HCO3- at other amino acid sites

• Function: carry oxygen (high affinity), carbon dixoide (low affinity), and assist pH balance

• lifetime of about 120 days with removal from macrophages + hemoglobin degradation

• produced:

  • in red bone marrow

  • stimulated by erythropoietin (in kidneys)

  • requires iron, b12, folic acid and amino acids

Describe the chemical composition of hemoglobin.

• Proteins with heme groups bind gases

  • O2, CO, and NO bind heme iron

  • CO2, HCO3- binds global amino acids

Hematopoiesis

• occurs in adult in the red bone marrow of axial skeleton, girdles, and epiphyses of humerus and femur

• stem cells divide and develop into mature erythrocyte

  • blast → cyte cells

  • Hematocytoblast (stem) → proerythroblast (committed) → erythroblast → reticulocyte → erythrocyte

• during development

  • genes are turned on to make hemoglobin, mRNA, and protein

  • accumulate hemoglobin proteins

  • Loose nucleus → reticulocyte

  • loose mRNA → mature erthrocyte

• stimulated by erthropoietine produced by kidney

  • stimulated by low oxygen

  • stimulates development of committed cells

• requires adequate iron, vitamins and amino acids for synthesis of hemoglobin

Anemia (LOW TYPES)

• lacking blood

• hemorrhagic anemia → blood loss is greater than the production

• Iron deficiency → insufficient iron

• Pernicious → vitamin deficiency (B12)

• Renal → lack of EPO production by kidney

• Aplastic → destruction of stem/progenitor cells → bone marrow damage

Anemia (HIGH TYPES)

• hemolytic → lysis of blood cells for acute reasons

• Thalassemias → genetic hemoglobin deficit

• Sickle cell anemia → point mutation in aggregations of hemoglobin + easy rupture

Polycythemia

• many blood cells

• excess of RBC that makes blood too thick

• vera → bone marrow cancer → proliferation of RBC

• Secondary → EPO over stimulation → high altitiude

• Blood doping → aerobic athletes artifically increase RBC to improve performance

Leukocytes definition

• nucleated cells that can migrate between tissues and blood

• for inflammation and immune response

Granulocytes

• secretory granules with effector molecules for the innate immune response

• 75% of leukocytes

• Neutrophils

  • small granules

  • phagocytes and destroy bacteria

  • 50-70%

• Eosinophils

  • large pink granules

  • contains protein which kills worms and proteases

  • 2%-4%

• Basophils

  • very large purple granules

  • lobed nucleus

  • bind to activated IgE and release histamines to induce inflammatory response

  • <1%

    
    

Agranulocytes

• 25% of leukocytes

• Lymphocytes

  • round nucleus with little cytoplasm

  • involved in adaptive immune system

  • classified into T-cells and B-cells which helps kill cancer cells and produce antibodies

  • 30%

• Monocytes

  • large cell with dented nucleus

  • becomes macrophages in tissues and phagocytic cleaning debri cells

  • 5%

Leukocyte production

• develops from stem cells → blast via mature forms

• gain granules + modify nucleus shape for granulocytes

• myeloid stem cells: neutrophils, eosinophils, basophils, and monocytes

• Lymphoid: T-cells, B-cell lymphocytes

• develops from hematopoietic stem cells in red bone marrow

Leukocytes disorders

Leukemias

• cancerous overproduction of WBCs

• acute → rapid in young

• chronic → slow in elderly

• Myeloid or Lymphoid

Infectious Mononucleosis

• caused by infection of lymphocytes

• highly contagious

Consequences: weakened immunity, infection risk, anemia, bleeding

Platelets

• small cell fragments from megakaryocytes

• contains granules with clotting chemicals

• sticks to damaged BV sites and initates clotting cascade

• production regulated by thrombopoietin

  
  

Hemostasis

• process preventing blood loss at sites of damage involving platelets and blood clotting

• Steps

  • vascular spasm (smooth muscle shortening stimulate by damage from endothelial cells or platelets)

  • Platelet plug formation (injury to endothelial cells lining the vessel exposes underlying fibers to which platelets adhere + platelets stick to each other → matrix → clot)

  • Coagulation/blood clotting → fibrin proteins form a mesh that traps RBC and platelets → blood clot

  • Clot retraction → shortening of threads within interconnected platelets → pulls clot together to close wound

  • Clot dissolution → protease called plasmin degrades fibrin fibrils

Hemostasis Limiting Factors

• anticoagulants

  • aspirin

    • inhibits the production of prostaglandin signaling molecules

  • Warfarin

    • prevents vitamin K-dependent + liver

  • Heparin

• smooth endothelium

• dilution of clotting factors

Give examples of hemostatic disorders and the consequences of these disorders

• thromboembolic → too much clotting

  • thrombo → stationary clot → tissue becomes ischemic and dies → heart attack

  • embolism → clot released and blocks vessels → stroke

• Thrombocytopenia → low platelet count

• impaired liver function → lack of clotting factors

• Hemophilia A,B,C → missing clotting factors (VIII, IX, XI)

Explain the basis of transfusion reactions.

• Transfusion reactions

  • aggulination → aggregation of erthrocytes by antibodies → clogging small vessels

  • lysis of erthyrocytes cells → release of hemoglobin → overload of kidney

• blood types are antigenic structures on the blood cell that fall into two groups with there being three types for one group and two types for the other group

ABO blood group

• three different alleles code for an enzyme that attaches carbs to an erythrocyte surface protein

• A allele attaches N-acetylgalactosamine

• B allele attaches galactose

• O allele enzyme is inactive

• Individuals produce antibodies against foreign blood group antigens and these can agglutinate RBCs

• A, anti-B antibodies can receive A or O

• AB, no antibodies can receive A, AB, B, or O

• B, anti-A antibodies can receive B, O

• O, anti-A and anti-B antibodies, O

• Rh

  • Rh+ and Rh-

  • Rh- an individual develops antibodies after exposure to Rh+

• Reactions:

  • agglutination → clogged BV

  • hemolysis → kidney failure

Describe the fluids uses to replace blood volume ant the circumstances for their use.

• transfusions of whole blood or packed RBCs

• isotonic saline or plasma expanders for short-term volume restoration

• used during blood loss, surgery, or trauma

Explain the diagnostic importance of blood testing.

Measures

• cell counts

• protein/enzyme levels

• electrolytes, hormones, and waste

compares results to normal reference ranges

performed by automated machines

crucial for disease diagnosis and monitoring