Unit 2: Specialised Connective Tissue
Table of Contents
1. Blood: Components and Functions
Blood is a fluid connective tissue consisting of a liquid extracellular matrix called plasma and formed elements (cells and cell fragments). It acts as the primary transport medium of the body.
A. Plasma
A straw-colored liquid making up about 55% of blood volume. It contains water (90-92%), proteins (albumin, globulins, fibrinogen), electrolytes, and nutrients.
B. Formed Elements
- Erythrocytes (RBCs): Biconcave discs lacking a nucleus; primary role is oxygen transport.
- Leucocytes (WBCs): Part of the immune system. Divided into Granulocytes (Neutrophils, Eosinophils, Basophils) and Agranulocytes (Lymphocytes, Monocytes).
- Thrombocytes (Platelets): Cell fragments essential for blood clotting and hemostasis.
2. Structure and Functions of Hemoglobin
Hemoglobin (Hb) is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates.
Structure
- Globin: A protein consisting of four polypeptide chains (two alpha and two beta chains in adults).
- Heme: Each globin chain is bound to a red pigment molecule called heme. Each heme group contains one iron ion (Fe2+) which can bind one oxygen molecule.
Functions
- Oxygen Transport: Binds oxygen in the lungs to form Oxyhemoglobin and releases it in tissues.
- Carbon Dioxide Transport: Carries about 23% of total CO2 as carbaminohemoglobin.
- Acid-Base Balance: Acts as a protein buffer by binding to hydrogen ions.
3. Blood as a Buffer and Blood Groups
Blood as a Buffer System
Blood maintains a constant pH (around 7.4) through various buffer systems, primarily the Bicarbonate Buffer System.
Blood Groups
| System | Description |
|---|---|
| ABO System | Based on the presence or absence of A and B antigens on RBC surfaces. |
| Rh Factor | Refers to the Rhesus antigen. Presence (Rh+) or absence (Rh-) is crucial for blood transfusion and pregnancy. |
| MN System | A minor blood group system based on M and N antigens; important in forensic science. |
| Golden Blood | The Rh-null blood group, lacking all Rh antigens. It is extremely rare. |
4. Bone and Cartilage: Structure and Types
Cartilage
A flexible, specialized connective tissue with a semi-solid matrix (chondroitin sulfate).
- Hyaline Cartilage: Most common; found in the nose, trachea, and ends of long bones.
- Elastic Cartilage: Contains elastic fibers; found in the external ear and epiglottis.
- Fibrocartilage: Strongest type; found in intervertebral discs.
Bone (Osseous Tissue)
A hard, calcified tissue providing structural support and mineral storage.
- Compact Bone: Dense outer layer consisting of Haversian systems (osteons).
- Spongy Bone: Located inside bones; contains a lattice-like structure called trabeculae.
5. Exam-Oriented Focus
Exam Tips
- Haversian System: This is a frequent question for Bone histology. Focus on terms like Lamellae, Lacunae, and Canaliculi.
- Rh Incompatibility: Understand the concept of Erythroblastosis Fetalis for short notes.
- Oxygen Dissociation: Be ready to explain how Hemoglobin structure allows for cooperative binding.
Common Mistakes
- Confusing **Plasma** with **Serum**. Serum is plasma minus the clotting factors.
- Thinking bone is a "dead" tissue. It is highly vascular and metabolically active!.
Frequently Asked Questions
- What are the components of the Bicarbonate buffer system?
- Differentiate between Hyaline and Elastic cartilage with examples.
- Explain the structure of an Adult Hemoglobin molecule.