Blood Composition and Functions

• Blood consists of 55% plasma and 45% formed elements
• Formed elements include red blood cells (RBCs), platelets, and white blood cells (WBCs), with WBCs comprising only 1% of blood volume

Blood Characteristics

• Blood is 5 times thicker than water, indicating its viscosity due to the concentration of formed elements
• Blood is sticky with a normal temperature of 100.4°F
• Blood pH ranges from 7.35 to 7.45, making it slightly alkalotic
• Color varies with oxygen levels: bright red indicates high oxygen, while dark red/blue indicates low oxygen

Blood Functions: Transportation

• Delibers oxygen, carbon dioxide, electrolytes, and nutrients from the gastrointestinal (GI) tract to body cells
• Transports hormones from glands to target cells, as well as enzymes, antibodies, and medication

Blood Functions: Regulation

• Maintains homeostasis through pH regulation via buffers and temperature regulation via plasma
• Plasma absorbs heat from muscles, and the body regulates blood flow to the skin through vascular changes
• Regulates osmotic pressure to adjust water content in cells and maintains fluid balance
• Water is added to the blood from the GI tract and is lost through sweat and urine

Blood Functions: Protection

• Facilitates blood clotting via platelets to prevent excessive bleeding from injuries like paper cuts
• Provides protection against infection through white blood cells

Plasma Composition

• Plasma is the fluid matrix of blood, accounting for 55% of blood volume
• It is composed of 92% water and 8% solutes
• Solutes include mostly proteins (7%), electrolytes, nutrients, hormones, enzymes, and waste products like urea and carbon dioxide

Plasma Proteins

• Blood is a colloidal fluid with proteins that exert osmotic pressure, preventing fluid loss from the blood as it moves through capillaries
• Lower protein levels in the blood can cause fluid to leave the vessels and enter the "third space," leading to edema or ascites
• Most plasma proteins, including albumins, galins, alpha and beta globulins, and fibrinogen, are synthesized in the liver by hepatocytes
• Immunoglobulins are produced by the immune system

Albumins

• Albumins account for 54% of plasma proteins and are the most abundant and smallest in size
• The major function is to maintain osmotic pressure between blood and surrounding tissue
• Important markers of nutrition

Globulins

• Globulins account for 38%
• Immunoglobulins or gammaglobulins participate in immune response
• Alpha and beta globulins are important for the transport of iron, lipids, and fats
• Made in the liver, except immunoglobulins which are made by the immune system

Fibrinogen

• Fibrinogen accounts for 7%
• Converted to fibrin to form a meshwork for blood clotting

Formed Elements

• Erythrocytes (RBCs), Leukocytes (WBCs) and Thrombocytes (platelets)

Leukocytes

• Granular Leukocytes: Neutrophils, Eosinophils and Basophils
• Agranular Leukocytes: T and B lymphocytes, Natural killer cells and Monocytes

Hematopoiesis

• Formation of Blood cells also known as hemopoiesis
• In children, this process occurs in the liver, spleen, thymus, lymph nodes, and red bone marrow
• In adults, it is limited to the red bone marrow, specifically in the sternum, vertebrae, pelvis, proximal femur, and proximal humerus
• Each cell has a specific lifespan controlled by negative feedback

Cell Lifespans

• RBCs: approximately 120 days
• WBCs: approximately 5 days (may last much longer)
• Platelets: approximately 7 days

Hematopoiesis Location

• Red bone marrow is highly vascularized connective tissue in spongy bone
• The site of all blood cell production
• In newborns, all bone marrow is red
• In adults, red bone marrow is converted to yellow bone marrow, which is mostly fat

Formation of Blood Cells

• All formed elements come from hematocytoblasts, or blood stem cells, which are undifferentiated and capable of dividing and differentiating into all blood cells
• Blood stem cells make two "daughter cells": myeloid stem cells and lymphoid stem cells
• Myeloid stem cells develop in the red bone marrow and give rise to RBCs, platelets, monocytes, and the granulocytes
• Lymphoid stem cells begin development in the red bone marrow but complete it in the lymphatic tissues

Erythropoiesis

• Process of changing a myeloid cell into an erythrocyte
• Takes 5-7 days and mostly happens in bone marrow
• Erythropoietin: A hormone that stimulates the change and abused by athletes
• Each stage has a nucleus until the normoblast stage, and each stage grows smaller in size

Red Blood Cell Anatomy

• Biconcave disc shape allows maximum flexibility
• Contains no nucleus or organelles, meaning no mitosis
• Cytoplasm is ⅓ volume of hemoglobin and uses glycolysis for ATP production
• Allows for RBCs to make ATP without using the oxygen it is carrying

Red Blood Cells: Biconcave Disc

• Optimal surface area for maximal capacity to carry oxygen
• Each has ~280 million hemoglobin molecules

Hemoglobin

• Respiratory pigment that is a Quaternary Protein
• Globin: 4 polypeptide chains (2 alpha, 2 beta)
• Heme: pigment in each of the 4 chains where Iron (Fe+) at center of each ring can attach reversibly with one oxygen molecule
• Each hemoglobin holds 4 Oxygen molecules

Hemoglobin + Iron

• Iron is necessary for normal Hgb function
• 67% of Iron in the human body is within the hemoglobin molecule
• Iron is lost daily in feces, urine, and during female menstrual cycle
• Must replace by eating it

Hemoglobin (Hb) Function

• Hb binds to oxygen for transport to cells (HgbO2 Oxyhemoglobin)
• Binds carbon dioxide away from cells (Hgb + CO = Carboryhemoglobin)

Fetal Hemoglobin

• Composed of 2 alpha and 2 gamma chains
• Has a high affinity for oxygen, enabling it to take oxygen from adult Hb and deliver it to fetal tissues
• Not produced after birth; normal hemoglobin does not ensure normal adult hemoglobin

Hematocrit (HCT)

• Percentage of total blood volume occupied by cells
• Normal Ranges
  • Male: 42-56%
  • Female: 38-46%
• Difference due to testosterone increasing EPO release

HCT Levels

• Increased HCT: Dehydration
• Decreased HCT: Defect, Dysfunctional

RBC Degradation

• Average lifespan of ~120 days
• RBC membrane fragility increases with age
• No nucleus, no regeneration
• Damaged RBCs die and are removed from circulation by macrophages in liver and spleen
• Iron and amino acids are recycled in bone marrow, transported by transferrin
• Heme -> biliverdin -> bilirubin -> urobilinogen -> uroblin (urine) or Sterocobilin (feces)

RBC Degradation Products

• Globin: Broken down into amino acids for protein synthesis
• Heme: Releases iron (transported via transferrin) and creates biliverdin
  • Biliverdin becomes bilirubin and is eliminated by urine and feces

Low and High Hematocrit

• Low Hematocrit = Anemia
• High Hematocrit = Polycythemia vera (blood is too thick)

Leukocytes

• White blood cells larger than RBC and Have nuclei and can divide and have special skills
• Chemotaxis Movement towards damaged/injured tissues and cells (chemical signal)
• Diapedesis macment out of the blood vessel

Varying Degrees of Phagocytosis of Leukocytes

• live between a few days to a few years
• During acute infections, WBCs may only last a few hours
• Leukocytosis: Abnormally high WBC count
• Leukopenke: Abnormally cow WBC cont

Granulocytes

• Have granules
  • Basophils (~1%)
  • Eosinophils (1-4%)
  • Neutrophils (60-70%)

Argandocytes

• No granules
  • Lymphocytes (20-40%)
  • Monocytes (3-8%)

Basophils

• Stains purple/blue
• Elevated with allergies and Parasites
• Holds histamines and heparin
  • Acute allergic reactions (anaphylaxis): vasodilates, increases capillary permeability, decreases clotting to cause the allergy

Eosinophils

• Stains red/orange
• Nucleus has two lobes that are connected
• Elevated with allergies and parasitic infections, autoimmune disease
• Enzymes which degrade inflammation - stimulating chemicals and Release toxic proteins that attack different parasites (ie, tapeworm)

Neutrophils

• Neutral Stain
• Nucleus is multilobar (2-5 lobes) Most common, wide range of physiologic affects During an active infection, your body is making many neutrophils so fast that sometimes immature cells are release Bands: an increase in circulating young neurophils

Lymphocytes

• Stains bluish
• Nucleus is dark and round with a small indentation
• Most of the cell is the nucleus
• Cytoplasm is light blue in color
• Increased in virus, leukemia
• Three different lymphocytes: B cells, T cells and Nk cells

Monocytes

• Largest WBC
• kidney/"horseshoe" nucleus
• Blue appearance of cytoplasm
• Increased in virus, fungal infection, leukemia
• Differentiate to macrophages found in liver, lung, lymph nodes, spleen, bone marrow

WBC Parts Overview

• Remove foreign material and debris
• Neutrophils and macrophages are active phagocytes
• Catarectal by chemotaxis

Neutrophils

• Respond most quickly to tissue damage by bacteria
• Use lysozymes, strong oxidants, defensins

Monocytes

• Take longer to arrive but arrive in larger numbers and destroy more microbes
• Enlarge and differentiate into macrophages

Lymphocytes

• Major "soldiers" of the immune system
• B-cells: Destroy bacteria and inactivate their toxins
• T-cells: Attack viruses, fungi, transplanted cells, cancer cells, and some bacteria
• Natural killer cells: attack a wide variety of infectious microbes and certain tumor cell

Thrombocytes (Platelets)

• Begin as megakaryocytes
• Average lifespan of ~7 days
• Removed by macrophages in the liver and spleen
• All about clotting

Thrombopoiesis control

• Thrombopoietin (THPO), also known as megakaryocyte growth and development factor
  • Produced by liver and kidney
  • THPO is bound to the outside of platelets
• Negative feedback system turns production on and off

Platelet Job

• Must occur quickly to stem blood loss
• Three phases
  • Vascular spasm
  • Platelet Plus Formation
  • Coagulation

Phase 1: Vascular spasm

• Immediate response to damaged vessel
• Vasoconstriction Smooth muscle clamps down, and Blood vessel diameter narrows
• Triggered by chemicals released by the damaged blood vessels

Phase 2: Platelet Plug Formation

• Damage to the blood vessel allows collagen fibers to be exposed
  • Platelet adhesion: Platelets o-Stick to these fives
• Platelets are activated and they extend many projections which allow platelets to come in contact with one another AND Chemicals cue released

Platelets: Chemicals Cased Phase

• Thromboxane A2 and ADP attract other platelets
• Serotonin and thromboxane A2 cause vasoconstriction

Phase 3: Coagulation

• Involves many substances which undergo a series of chemical reactions
  • Ca+, inactive enzymes, molecules that promote reactions associated with platelets or released by damaged tissue
• 13 different factors, indicated by roman numerals and the ultimate goal is formation of Fionh

Substunces involved in Coagulation

• Calcium, Plaklets and Vitamin K
• Clotting factors (13 in total)
• Most are inactive enzymes produced in live Vitamin K: Fat-Soluble vitamin-and require synthesis of clotting factors

Coagulation Enzyme

• May Occur by one of two pathways

1. Intrinsic pathway (contact activation)
2. Extrinsic pathway (damage offside of theressee)

• Both pathways lead -
  • Both Pathways lead to formation of prothrombinase
  • Prothrombinase condens prothrombin into twombin
  • Thrombin Convens fibrinogin to form the threads of the clot

Clot Retraction

• Tightening of the Fionh dor
• As the clot vetruts, it pulls the edges of the damaged blood vessels closer together
• Occur within once it is done with its job the enzyme: Plasmin breaks down de fiorin (Fibrinolysis)

Thrombocytosis: Too Many Platelets

• Essential-due to bore marrow issue
• Secondary-made due to other issue (Infection, von deficiency and medications)

Happens

• Causes over cotting

Thrombocytopenia: Not Enough Platelets

• Mess circulating- Huck in enlarged Spleen Less made: Bove manan disorder More broucen down-Infections, pregnancy, autoimmune diseases

Thrombocytopenia: Problems

• Difficulty clotting
• Causes too much bleeding

Complete Blood Cont (cbc) Also Known As "Differential cont"

• Complete examination of many blood components testing: Cell numbers/percentages, cell size and Hema crit

Complete Blood Cont (cbc) Results

• Hemoglobin

Blood Types

• Type A

  • Has A cuntagen
  • Anti-B antinaly

• Type B

  • thes B antigen
  • Anti-A anticaly

• Type AB

  • has antigens A and B
  • No antibodies

• Type O

  • Has No antigens
  • Aris A and B anti-banes

An overview of blood composition, including plasma and formed elements such as red blood cells, platelets, and white blood cells. Also describes blood characteristics like viscosity, temperature, pH, and color. Key functions of blood include transportation and regulation.