Chapter 18- Blood

Functions of Blood

Blood functions = Transport + Protection + Homeostasis

  1. Transportation

  • Oxygen

  • Hormones

  • Carbon dioxide

  • Waste/byproducts

  • Nutrients to organs

  1. Defense

  • Leukocytes (WBCs) defend against pathogens

  1. Protection from blood loss

  • Blood clotting substances prevent bleeding

  1. Homeostasis

  • Regulates body temperature

  • Maintains blood pH

  • Helps regulate water content of body cells

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Composition of Blood

Hematocrit

= Percentage of erythrocytes (RBCs) in blood

Normal ≈ 45%

Packed Cell Volume (PCV)

= Volume of erythrocytes in centrifuged blood

Layers of Centrifuged Blood

Bottom → Top

  1. Erythrocytes (RBCs)

  • Heaviest

  • Settle at bottom

  1. Buffy Coat

  • Thin middle layer

  • Contains WBCs + platelets

  1. Plasma

  • Top layer

  • Pale straw-colored fluid

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Characteristics of Blood

Color

Bright red = more oxygen (O₂)

Dusky red = less oxygen (O₂)

Texture

  • Viscous

  • Sticky

Temperature

  • 38°C (100.4°F)

  • Slightly warmer than body temp

pH

7.35–7.45

= slightly alkaline

Amount

Female = 4–5 L

Male = 5–6 L

Average = 5 L

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Blood Plasma

Plasma

= Fluid part of blood

Plasma is mostly:

Water (92%)

Most abundant dissolved substance:

Protein

3 Major Plasma Proteins

  1. Albumin

  • MOST abundant

  • Regulates osmotic pressure

  1. Globulins

  • 2nd most abundant

  • Includes antibodies

  • Important for immunity

  1. Fibrinogen

  • Needed for blood clotting

Protein Production

Most plasma proteins = made in liver

Gamma globulins = made by plasma cells

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Hematopoiesis (Blood Cell Formation)

After Birth

Most blood cell formation occurs in:

Red bone marrow

Adults:

  • Cranial bones

  • Pelvic bones

  • Vertebrae

  • Sternum

  • Proximal epiphysis of:

    • Femur

    • Humerus

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Formed Elements (Blood Cells)

  1. Erythrocytes (RBCs)

    → carry oxygen

  1. Thrombocytes (Platelets)

    → blood clotting

  1. Leukocytes (WBCs)

    → immune system

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Hemopoietic Growth Factors

Erythropoietin (EPO)

→ stimulates RBC production

Thrombopoietin

→ stimulates platelet production

Cytokines

→ stimulate WBC production

Memory Trick:

Never Let Monkeys Eat Bananas

(For WBC order)

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Erythrocytes (RBCs)

Function

Transport oxygen

Lifespan

120 days

Shape

Biconcave disc

Hemoglobin (Hgb)

Each RBC contains:

250–300 million hemoglobin molecules

Oxyhemoglobin

= Hemoglobin with oxygen attached

Deoxyhemoglobin

= Hemoglobin after oxygen released

Carbon Dioxide

Travels mostly as:

Bicarbonate ions in plasma

Percent Sat

= % of hemoglobin occupied by oxygen

Pulse Oximeter

Measures:

Percent saturation

Hypoxia

= Low oxygen levels

Kidneys + Low Oxygen

Kidneys release:

Erythropoietin (EPO)

→ stimulates more RBC production

Old RBC Removal

Removed by:

Macrophages

Locations:

  • Bone marrow

  • Liver

  • Spleen

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RBC Breakdown Products

Biliverdin

= Green pigment

Bilirubin

= Yellow pigment

→ goes to liver to make bile

Too much bilirubin = jaundice

Stercobilin

→ gives feces brown color

Urobilin

→ gives urine yellow color

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Erythrocyte Disorders

Anemia

= Low RBCs or hemoglobin

Sickle Cell Anemia

  • Genetic disorder

  • Abnormal crescent-shaped hemoglobin

  • Blocks blood flow

Iron Deficiency Anemia

= Most common anemia

  • Not enough iron

Megaloblastic Anemia

= Vitamin B12/folate deficiency

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Chapter 21 – Lymphatic & Immune / Blood (CONDENSED EXAM NOTES)

Leukocytes (WBCs)

Also called:

White blood cells (WBCs)

Function

Protection in immune system

Range

5,000–10,000

Diapedesis

= WBCs squeeze through vessel walls

Positive Chemotaxis

= Movement toward chemicals

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Granulocytes

(Have many granules)

1. Neutrophils

MOST COMMON WBC

  • Multi-lobed nucleus

  • Increase in acute infection

2. Eosinophils

  • Increase in:

    • Parasites

    • Allergies

  • Contain antihistamine

3. Basophils

LEAST COMMON

  • Histamine + heparin

  • Increase inflammation

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Agranulocytes

(Have few granules)

1. Lymphocytes

Major Types:

Natural Killer Cells (NK)

→ kill cancer & virus-infected cells

B cells

→ antibodies

→ memory cells

T cells

→ attack infected/diseased cells

2. Monocytes

Largest WBC

  • Horseshoe/kidney-shaped nucleus

  • Become macrophages

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WBC Order (Most → Least Common)

Never Let Monkeys Eat Bananas

Neutrophils

Lymphocytes

Monocytes

Eosinophils

Basophils

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Leukocyte Disorders

Leukopenia

= Low WBC count

Leukocytosis

= High WBC count

Leukemia

= Cancer of leukocytes

Lymphoma

= Cancer involving:

T or B lymphocytes

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Platelets (Thrombocytes)

Function

Blood clotting

Range

150,000–400,000

Thrombocytosis

= High platelet count

Thrombocytopenia

= Low platelet count

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Hemostasis

= Process of stopping bleeding

Hemostasis

= Body seals ruptured blood vessel

Hemorrhage

= Excessive bleeding

Stages of Hemostasis

  1. Vascular Spasm

    → vessel constricts

  1. Platelet Plug Formation

    → platelets clump

  1. Coagulation

    → clot forms

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Clotting Disorders

Hemophilia

= Failure to clot properly

Thrombophilia

= Increased clotting tendency

Thrombus

= Stationary clot

Embolus

= Moving clot

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Blood Types

Agglutination

= Clumping of RBCs

Blood Type Determined By:

Antigens on RBC membrane

Antibodies

Travel in:

Plasma

Universal Donor

O−

Universal Recipient

AB+

Most Common Formed Element

RBCs

Most Common WBC

Neutrophil