Anatomy Ch. 20

Blood…

• Transports

• Carries from one place to another in the body

• Carries molecular evidence for the bodies activities

• Examination of blood is essential in clinical assessment

Blood is used to screen for evidence:

• Disease

• Substance abuse

• Nutritional status

• Pregnancy

Blood circulation

• Is initiated by pumping of the heart

• Blood leaves the heart in arteries

  • Branch repeatedly until they become capillaries

Capillaries

• Deliver oxygen and nutrients to tissues

• Removes carbon dioxide and cellular wastes and returns the blood to heart

• Sent to the lungs where released, and oxygen is picked up

Veins…

• Return blood to the heart and sent though body again

Functions of blood

1. Carries respiratory gases, nutrients, and hormones

2. Conveys immune cells to sites of infection (connective)

3. Helps body regulate temp

   1. Blood volumes in females is less than that in males

Composition of blood…

• Blood looks homogenous

• Contains both cellular and liquid components

• Specialized connective tissue

Cellular component

• Living formed elements

• Erythrocytes, leukocytes, etc

Liquid component

• Nonliving fluid element suspends cellular component (plasma)

The _______ is the percentage of the blood volume that consists of erythrocytes or RBC’s = oxygen carrying capacity

• Hematocrit

Hematocrit cont…

• Normal values may vary

  • Higher in newborns 42% to 68%

  • Males: around 47%

  • Females around 42%

Blood plasma

• Straw colored, sticky fluid portion of blood

• Approximately 90% water

Blood plasma contains over 100 solutes:

• Proteins: albumin, globulins and clotting proteins (fibrinogen) (carriers)

• Nonprotein nitrogenous wastes: lactic acid, urea, creatinine

• Organic nutrients: glucose, carbohydrates, amino acids

• Electrolytes (ions): sodium, potassium, calcium, chloride, bicarbonate

• Respiratory gases: oxygen and carbon dioxide

Cellular (formed) elements:

• Produced in bone marrow

• Erythrocytes (RBCs)

• Platelets

• Leukocytes

Formed elements: unusual features of erythrocytes and platelets

• Not true cells - RBC lack nuclei and organelles, and platelets are cell fragments

• Cannot divide and survive in the bloodstream for only a short time (few hours to months) before being replaced by new cells or broken down and recycled

Formed elements: unusual features of leukocytes

• Staining of blood cells (Wright’s stain)

• Acidic dye: eosin; stains pink

• Basic dye: methylene blue; stains blue and purple

Formed elements: red blood cells

• Erythrocytes

• RBCs are manufactured continuously in bone marrow of pelvis, skull, ribs, vertebrae, and ends of long bones

• Before being released from bone marrow, BRCs lose their nucleus and synthesize hemoglobin

RBCs contain the plasma membrane protein _______

• Spectrin

Spectrin…

• Give erythrocytes their flexibility

• Allow them to change shape as necessary

• Life span of RBC is 120 days

Formed elements: erythrocytes

• Oxygen-transporting cells

• Most numerous of the formed elements

• Have no organelles or nuclei

• Are the ideal measuring tool for estimating sized of nearby structures

Formed elements: erythrocytes cont…

• Dedicated to respiratory gas transport

• Cytoplasm is packed with hemoglobin

• Hemoglobin reversibly binds with oxygen

• Composed of the globe, two alpha and two beta chains, bound to a heme group

• Heme group has iron atoms binds to one oxygen molecule

• Hemoglobin can transport four molecules of oxygen

_______ of iron on the hemoglobin gives blood its red color

• Oxidation

Formed elements: erythrocytes cont…

• Pick up O2 at lung capillaries and distribute throughout body

• Release O2 across other tissue capillaries

• Structural characteristics contribute to respiratory function

  • Biconcave shape (donut shape) —> 30% more surface area (allows more oxygen)

  • 97% hemoglovin

  • Lack mitochondria (do not consume O2 they pick up)

Formes elements: WBCs

• Less numerous than RBCs (WBCs are higher if sick)

• Complete cells, with organelles and nuclei

• Protect the body from infectious microorganisms: fight infections

• Function outside the bloodstream in loose connective tissue

• Various chemicals produced or released at infection sites attract circulating WBCs

Formed elements: WBCs cont…

• Leave the capillaries by squeezing between the endothelial cells that form the capillary walls

• Diapedesis

• Once in loose CT they move by amoeboid motion

Diapedesis

• Circulating leukocytes leave the capillaries

Formed elements: WBCs cont…

• Originate in bone marrow are released continuously into the blood

• Bone marrow also stores WBC and released them in mass during a serious infection

• WBC count - marker for infectious disease

Leukocytosis

• Patient with a count exceeding 11,000 per cubic mm indicated infection of inflammation

White blood cells (leukocytes) are usually ______ than red blood cells, contain a nucleus

• Larger

WBCs appear ________ without staining

• Translucent/white

Granular leukocytes

• Contain granules in cytoplasm and lobed nucleus

• Neutrophils, eosinophils, and basophils

• Stains^

Granular leukocytes

• Lack granules and have a circular or indented nucleus

• Monocytes and macrophages

• ^ Can switch phenotypes and eat up infection

• Also decrease inflammation

Lymphocytes

• Help fight infection

• T and B cells

• ^ Long term, chronic

Granulocytes

• Neutrophils (neutral, purple)

• Eosinophils (acidic dye, red)

• Basophils (basic, blue/dark purple)

Granulocytes cont…

• Contain cytoplasmic granules that stain specifically (acidic, basic, or both) with Wright’s stain

• Are larger and usually shorter-lived than RBCs

• Have loves nuclei

• Are all phagocytic cells

• Make up 1% of the total blood volume