Blood is a specialized connective tissue that circulates throughout the body, carrying oxygen, nutrients, hormones, and waste products while playing crucial roles in immunity, temperature regulation, and homeostasis.

Overview

Blood is the vital fluid component of the cardiovascular system that serves as the body's primary transport medium. Making up approximately 7-8% of human body weight, this complex tissue consists of cellular components suspended in a protein-rich fluid called plasma.

Composition

Plasma (55%)

Primarily water (90-92%)
proteins including:
- albumin for osmotic balance
- immunoglobulins for immune defense
- fibrinogen for blood clotting
Electrolytes and minerals
Hormones and nutrients

Cellular Components (45%)

Red Blood Cells (erythrocytes)

Contain hemoglobin for oxygen transport
Biconcave disc shape for maximum surface area
Lack nuclei in mature form
Live approximately 120 days

White Blood Cells (leukocytes)

Defend against infection and disease
Multiple types including:
- neutrophils for bacterial defense
- lymphocytes for immune response
- monocytes for tissue repair

Platelets (thrombocytes)

Essential for blood clotting
Activate during vessel injury
Form platelet plug
Release clotting factors

Functions

Transport

Oxygen delivery to tissues
Carbon dioxide removal
Nutrient distribution
hormone messenger transport
Waste product collection

Protection

immune system component
inflammation response
wound healing
pathogen resistance

Regulation

Blood Types

ABO system (blood types)
- Type A
- Type B
- Type AB
- Type O
Rh factor positive or negative
Critical for blood transfusion procedures

Common Disorders

Composition Disorders

Clotting Disorders

Medical Applications

Research and Development

Blood's complexity and importance make it a crucial area of ongoing medical research and clinical practice. Its multiple functions and interactions with virtually every body system highlight its fundamental role in maintaining life and health.