Cardiovascular System: Blood - Lab

Hematocrit (HCT)

• Is the % of erythrocytes, or red blood cells (RBCs), in a whole blood sample

• Determined by separating formed elements from plasma and measuring the packed RBCs volume

Ranges of Hematocrit

• Adult males: 42-52%

• Adult females: 37-47%

Abnormal Elevated Hematocrit

• Reasons are

  • Being at high altitude

  • Elevated testosterone level

  • Certain diseases

  • “Blood Doping”

Blood Doping

Refers to any of several methods used to increase the blood oxygen-carrying capacity.

Hematocrit is one way to measure which of the following characteristics of the blood?

Oxygen-carrying capacity

BLOOD APR:

Neutrophil (Blood Peripheral Smear)

• Location: Circulating blood

• Description:

  • Leukocyte (white blood cell) with multilobed nucleus (typically 3-5 lobes); lobes connected by nuclear strands)

  • Fine, specific cytoplasmic granules appear pale pink in blood smears after staining with Wright or Giemsa method

  • Nonspecific cytoplasmic granules, which do not stain with Wright or Giemsa method, represent lysosomes

• Also known as: Polymorphonuclear leukocyte

Neutrophil Function

• Function:

  • Phagocytosis of infectious pathogens, especially bacteria (number in blood increases with bacterial infection)

  • Release antimicrobial agents

• Comments:

  • Neutrophils represent 60-70% of circulating leukocytes (most numerous granulocyte)

  • Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

  • Phagocytosis (Greek: phago = to eat + kytos = cell + osis = process) is process by which cell engulfs large particles (e.g., microorganisms, cells, and cell fragments) in membrane-bound vesicle

Platelet (Blood Peripheral Smear)

• Location: Circulating Blood

• Description:

  • Small, disc-shaped cell fragment (approximately 2 µm in diameter)

  • Lacks nucleus

  • Formed by fragmentation of cytoplasm of megakaryocyte (a cell in red bone marrow)

• Also known as: Thrombocyte (abnormally low in circulating blood known as thrombocytopenia)

Platelet Function

• Function: Contributes to clot formation

• Comments: Micrometer (µm), also known as a micron, is 1/1,000 of a millimeter

Erythrocyte (Blood Peripheral Smear)

• Location:

  • Blood vessels of body

  • Heart

• Description:

  • Biconcave disc shape

  • Mature cells lack nuclei and organelles

  • Make up 99% of the formed elements of blood

• Also known as: Red blood cell (RBC)

Erythrocyte Function

Transports oxygen and carbon dioxide to and from tissues of body

Nucleus of Neutrophil

• Location: Neutrophil

• Description:

  • Largest organelle

  • Typically has 3-5 lobes (multilobed) connected by thin nuclear strands

  • Nuclear envelope comprised of double membrane (i.e., two lipid bilayers)

  • Contains cellular DNA and nucleolus

Nucleus Function (Neutrophil, Eosinophil, Basophil)

• Functions:

  • DNA transcription into mRNA

  • Ribosomal RNA synthesis and ribosome subunit assembly (in nucleolus)

• Comments:

  • Staining of DNA with basic histological dyes like hematoxylin depends on transcriptional activity: DNA undergoing active transcription, called euchromatin, stains lightly because it is less folded and, therefore, less dense; transcriptionally inactive DNA, or heterochromatin, is tightly packed and condensed and, therefore, stains more darkly

Erythrocyte (Neutrophil)

Neutrophil (Neutrophil)

Cytoplasmic Granules in Eosinophil

• Location: Cytoplasm

• Description:

  • Large, specific cytoplasmic granules appear deep pink in blood smears after staining with Wright or Giemsa method

  • Nonspecific cytoplasmic granules, which do not stain with Wright or Giemsa method, represent lysosomes

Cytoplasmic Granules in Eosinophil Function

• Function:

  • Contain agents that act on parasites (e.g., worms)

  • Contain enzymes that hydrolyze phagocytosed antigen-antibody complexes

• Comments:

  • Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

  • Phagocytosis (Greek: phago = to eat + kytos = cell + osis = process) is process by which cell engulfs large particles (e.g., microorganisms, other cells, or cell fragments) and forms a membrane-bound vesicle

Eosinophil

• Location:

  • Circulating blood

  • Mucous membranes of respiratory, digestive, and lower urinary tracts

• Description:

  • Nucleus typically has two large lobes (bilobed) connected by thin nuclear strand

  • Large, specific cytoplasmic granules appear deep pink in blood smears after staining with Wright or Giemsa method

Eosinophil Function

• Function:

  • Phagocytosis of antigen-antibody complexes, allergens, and inflammatory chemicals

  • Releases enzymes that destroy parasitic worms

• Comments:

  • Eosinophils represent 2-4% of circulating leukocytes

  • Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

  • Phagocytosis (Greek: phago = to eat + kytos = cell + osis = process) is process by which cell engulfs large particles (e.g., microorganisms, other cells, or cell fragments) and forms a membrane-bound vesicle

Erythrocyte (Eosinophil)

Nucleus of eosinophil

• Location: Eosinophil

• Description:

  • Largest organelle

  • Nucleus has two lobes (bilobed); connected by thin chromatin filaments

  • Nuclear envelope comprised of double membrane (i.e., two lipid bilayers)

  • Contains cellular DNA and nucleolus

• Function: Same as other blood cells

• Comments: Same as other blood cells

Basophil

• Location: Circulating blood

• Description:

  • Nucleus typically large with two lobes (bilobed) frequently described as U- or S-shaped

  • Large, specific cytoplasmic granules that appear blue-black in blood smears after staining with Wright or Giemsa method

  • Nonspecific cytoplasmic granules, which do not stain with Wright or Giemsa method, represent lysosomes

  • Granules frequently obscure nucleus

Basophil Function

• Function:

  • Initiates immune response

  • Secretes histamine and heparin

• Comments:

  • Basophils represent <1% of circulating leukocytes

  • Resemble mast cells of connective tissue

  • Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

Erythrocytes (Basophil)

Cytoplasmic granules in Basophil

• Location: Cytoplasm

• Description:

  • Large, specific cytoplasmic granules dark appear blue-black in blood smears after staining with Wright or Giemsa method

  • Nonspecific cytoplasmic granules, which do not stain with Wright or Giemsa method, represent lysosomes

  • Granules frequently obscure nucleus

Cytoplasmic granules in Basophil Function

• Function: Contain histamine, heparin, chemotactic factors for eosinophils and neutrophils, proteases, chondroitin sulfate, and peroxidase

• Comments: Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

Nucleus of Basophil

• Location: Basophil

• Description:

  • Largest organelle

  • Large nucleus with two lobes (bilobed); frequently described as U- or S-shaped

  • Nuclear envelope comprised of double membrane (i.e., two lipid bilayers)

  • Contains cellular DNA and nucleolus

Platelet (Basophil)

Erythrocyte (Lymphocyte)

Lymphocyte

• Location:

  • Throughout tissues of body

  • Circulate in blood and lymphatic vessels between lymphoid tissues and other body tissues

• Description:

  • Three classes: B lymphocyte (B cell), T lymphocyte (T cell), and natural killer (NK) cell

  • Two main types of T lymphocyte: helper T lymphocyte and cytotoxic T lymphocyte

Lymphocyte Function

• B lymphocyte (15-30% of lymphocytes in body) responsible for humoral (Latin: humor = fluid) immune response: activation and differentiation into plasma cells (produce specific antibodies in response to specific antigen as primary immune response) or memory B lymphocytes (secondary immune response)

• T lymphocyte (70-85% of lymphocytes in body): responsible for cell-mediated immune response

• Natural killer (NK) cell: responds to multiple antigens and can kill wide variety of infected cells and cancer cells

Lymphocyte Comments

• Lymphocytes represent 20-25% of circulating leukocytes

• Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

• B lymphocytes called "B" because they are derived in chickens from lymphoid organ known as bursa of Fabricius

• Antibodies secreted into loose connective tissue enter lymphatic system and then bloodstream

• Latin: humor = fluid

• Micrometer (µm), also known as a micron, is 1/1,000 of a millimeter

Nucleus of Lymphocyte

• Location: Lymphocyte

• Description:

  • Largest organelle

  • Round or slightly indented; occupies most of cytoplasm

  • Nuclear envelope comprised of double membrane (i.e., two lipid bilayers)

  • Contains cellular DNA and nucleolus

• Comments: Same as other blood cells

Nucleus of Lymphocyte & Monocyte Function

• Function:

  • DNA replication

  • DNA transcription into mRNA

  • Ribosomal RNA synthesis and ribosome subunit assembly (in nucleolus)

• Comment:

  • Staining of DNA with basic histological dyes like hematoxylin depends on transcriptional activity: DNA undergoing active transcription, called euchromatin, stains lightly because it is less folded and, therefore, less dense; transcriptionally inactive DNA, or heterochromatin, is tightly packed and condensed and, therefore, stains more darkly

  • Micrometer (µm), also known as a micron, is 1/1,000 of a millimeter

Monocyte

• Location:

  • Circulating blood

  • Connective tissue

• Description:

  • Largest leukocyte (15-20 µm in diameter)

  • In connective tissue, they transform into macrophages

Monocyte Function

• Function: Phagocytosis

• Comment:

  • Monocytes represent 3-8% of circulating leukocytes

  • Leukocytes (white blood cells) divided into two groups: granulocytes (neutrophils, eosinophils, and basophils) and agranulocytes (lymphocytes and monocytes)

  • Micrometer (µm) is 1/1,000 of a millimeter

Nucleus of Monocyte

• Location: Eccentrically placed in monocyte

• Description:

  • Largest organelle

  • Large, ovoid or kidney-shaped (horseshoe) nucleus

  • Nuclear envelope comprised of double membrane (i.e., two lipid bilayers)

  • Contains cellular DNA and nucleolus

Erythrocyte (Monocyte)

Platelet (Monocyte)