Week 3 (The Blood) Flashcards
The Blood
Blood is a fluid connective tissue, composed of formed cellular elements suspended in a liquid medium called plasma.
formed cellular elements:
*erythrocytes (red blood cells, RBCs)
*leukocytes (white blood cells, WBCs)
*thrombocytes (platelets)
Functions of the Blood
Transportation
*deliver O2, nutrients eg. glucose, amino acids to cells
*transport waste products eg. CO2 from cells for
elimination
* transport hormones
*distribute heat throughout the body
Regulation (helps maintain homeostasis)
*maintain pH (carries buffers)
*maintain fluid and electrolyte balance
*maintain body temperature
Protection
*coagulation (clotting): prevent blood loss
*immunologic: prevent infection (WBCs, antibodies)
Physical Properties of Blood
Blood Volume:
5-6 L in males
4.5-5.5 L in females
pH: 7.35 – 7.45
Specific Gravity: 1.050
Viscosity: 4.5 – 5.5
Hematopoiesis (Blood Cell Formation)
(Blood Cell Formation)
*Occurs in red bone marrow.
*Sites of hematopoiesis in adults:
Skull, sternum, ribs, upper ends of long limb bones (humerus, femur), vertebrae, and pelvis.
BLOOD CELL COUNTS AND HEMATOCRIT
Blood Cell Counts
Red Blood Cells
Male: 4.7 to 6.1 million/μL
Female: 4.2 to 5.4 million/μL
White Blood Cells
4000 to 11 000 /μL
Platelets
150 000 to 450 000 /μL
Hematocrit
packed cell volume (PCV)
volume % of erythrocytes in blood
Male: 42 to 52 %
Female: 37 to 47 %
Blood Components
*Plasma (55%) – Contains water, ions, plasma proteins, respiratory gases, nutrients, waste products, and hormones.
*Cells (45%) – RBCs, WBCs, and platelets develop from stem cells in red bone marrow.
Plasma Components
*Water (90%)
*Plasma Proteins (8%)
Albumin: Acts as a buffer and helps maintain osmotic pressure.
Gamma Globulins: Antibodies.
Fibrinogen and Other Clotting Factors.
Complement Proteins and Transport Proteins.
Electrolytes, Nutrients, and Waste
*Products. (~1%)
Erythrocytes (Red Blood Cells)
*Manufactured by erythropoiesis.
*Shape: Circular, biconcave, and disc-shaped.
Advantages of Biconcave Shape
*Increased surface area for gas exchange.
*Flexibility to pass through capillaries.
Factors Affecting Erythropoiesis
Tissue Oxygenation
Hypoxia (triggers erythropoietin (EPO) release)
Erythropoietin (EPO)
Hormone produced by the kidneys to stimulate RBC production.
State of Bone Marrow
State of Liver
Nutritional Factors
Vitamins:
Vitamin B12
Folic Acid
Vitamin B6, B2, C, A, E
Nicotinic Acid (Niacin)
Protein: Amino acids
Minerals:
Iron
Copper
Cobalt
Other Hormones
Androgens
Estrogens
Growth Hormone
Thyroxine
Cortisol
Characteristics of Mature RBCs
Anucleate (no nucleus).
Lack mitochondria and organelles to maximize space for hemoglobin.
- do not divide / reproduce
- ↑ efficiency- more space to carry haemoglobin
*↓ weight- travel faster
*more O2 delivered to the tissues as organelles not present to consume it
*Life span: 100–120 days.
Functions of RBCs
Transport O₂ and CO₂.
Buffer blood pH.
Contribute to blood viscosity.
Hemoglobin (Hb)
– Primary Content of RBCs
Gives RBCs their characteristic red color.
Iron-containing protein with a quaternary structure.
Composed of two parts: Haem and Globin.
Functions of Hemoglobin
Transports O₂ and CO₂.
Maintains blood pH.
Controls vascular tone, mediated by nitric oxide (NO).
Normal Mean Concentration of Hb in Blood
adult males:
15.5 g/dL (range 14 – 18 g/dL)
adult females:
14 g/dL (range 12 – 16 g/dL)
Hemoglobin Structure
- Globin (97% of Hb Molecule)
Protein component of Hb.
Tetramer structure: consists of two α subunits and two β subunits.
Each subunit binds to a haem group. - Haem Group (3% of Hb Molecule)
Iron-containing porphyrin ring, composed of 4 pyrrole rings.
Each haem group contains one iron atom, which binds reversibly with one molecule of O₂.
(1 Hb molecule carries 4 molecules of O₂.)
Types of Hemoglobin
- Oxyhemoglobin
Hb bound to O₂ (bright red).
O₂ loading occurs in the lungs. - Deoxyhemoglobin
Hb after O₂ is released (dark red).
Occurs in the tissues. - Carbaminohemoglobin
Hb bound to CO₂.
20% of CO₂ in the blood binds to the globin component of Hb.
CO₂ loading occurs in the tissues.
Red Blood Cells – Life Cycle
Lifespan: 100–120 days
Destruction: Occurs in macrophages of the spleen, liver, and bone marrow
Hemoglobin (Hb) Breakdown:
*Hb is split into haem and globin components
*Globin chains are broken down into amino acids for reuse
*Iron from the haem group is released and transported to:
+Various tissues for storage
+Red bone marrow for the synthesis of new hemoglobin
Haem Group Conversion:
*The remaining haem is converted into biliverdin, then into bilirubin
*Bilirubin metabolism occurs in the liver, with its derivatives:
+Secreted in bile and excreted in feces (gives feces its characteristic color)
+Excreted in urine, contributing to its color
Leukocytes (White Blood Cells)
WBCs are the only blood components that are complete cells with a nucleus and organelles.
Functions of White Blood Cells
Defend against diseases and infections.
Remove toxins and tumor cells.
Can leave capillaries by diapedesis (migration).
Categories of WBCs
Granulocytes:
Contain membrane-bound granules.
*Neutrophils (60-70%)
*Eosinophils (1-4%)
*Basophils (0.25-0.5%)
Agranulocytes
Lack granules.
*Lymphocytes (25-33%)
*Monocytes (2-6%)
Neutrophils
Nucleus: Multilobed (3–6 lobes)
Function: Phagocytize bacteria
Eosinophils
Nucleus: Bilobed
Granules: Coarse, stain deep red to crimson
Functions:
*Defense against parasites (release digestive enzymes; worms too large to be ingested)
*Lessen the severity of allergies
*Phagocytize antigen-antibody complexes
*Release histaminase (reduces inflammation)
Basophils
Nucleus: Lobed, U- or S-shaped with 2 or 3 conspicuous constrictions
Granules: Coarse, dark purple or black
Functions:
*Release histamine (inflammatory chemical) and other mediators of inflammation
*Attract other WBCs to the area
*Contain heparin (anticoagulant)
