This document summarizes the composition and functions of blood. It discusses that blood is composed of plasma, red blood cells, white blood cells, and platelets. It then outlines the main functions of blood which include: transporting oxygen, nutrients, hormones, and waste; regulating body temperature, pH, and water balance; and providing defense against pathogens through the immune response.

1. COMPOSITION
&
FUNCTIONS OF BLOOD
PRESENTED BY
RUBEENA BEGUM
Department of Pharmacology

2. CONTENTS
• INTRODUCTION
• PROPERTIES OF BLOOD
• COMPOSITION
• FUNCTIONS

3. INTRODUCTION
• Blood is a fluid connective tissue
• It is known as the ‘fluid of life’ as it carries oxygen from lungs to all body parts and
carbon dioxide from all body parts to the lungs
• Also known as ‘fluid of growth’ as it carries nutritive substances from the digestive
system and hormones from endocrine gland to all the tissues
• Also called the ‘fluid of health’ as it protects the body against the diseases and helps
in removing waste products and unwanted substances from the body by transporting
them to the excretory organs like kidneys

4. PROPERTIES OF BLOOD
• Blood: Red
• Arterial Blood: Scarlet red as it contains more oxygen
• Venous Blood: Purple red because of more carbon dioxide
Colour
• Normal Adult: 5L (In females, it is slightly less and is about 4.5 L)
• Newborn Baby: 450mL
• It is about 8% of the body weight in a normal young healthy adult, weighing about 70 kg
Volume
• It is slightly alkaline
• Its pH in normal conditions is 7.4
Reaction & pH
• Total blood: 1.052 to 1.061
• Blood cells: 1.092 to 1.101
• Plasma: 1.022 to 1.026
Specific Gravity
• Blood is five times more viscous than water
• It is mainly due to red blood cells and plasma proteins
Viscosity

5. COMPOSITION OF BLOOD

8. FUNCTIONS OF BLOOD
• Nutritive substances such as glucose, amino acids, lipids and vitamins derived
from digested food are absorbed from gastrointestinal tract
• Blood carries these substances to different parts of the body for growth and
production of energy
NUTRITIVE
FUNCTION
• Blood is responsible for the transport of respiratory gases
• It carries oxygen from alveoli of lungs to different tissues and carbon
dioxide from tissues to alveoli
RESPIRATORY
FUNCTION
• Waste products formed in the tissues during various metabolic activities
are removed by blood and carried to the excretory organs like kidney, skin,
liver, etc. for excretion
EXCRETORY
FUNCTION
• Hormones which are secreted by ductless (endocrine) glands are released
directly into the blood and transported to their target organs/tissues
• Blood also transports enzymes
TRANSPORT
OF HORMONES
AND ENZYMES

9. • Water content of the blood is freely interchangeable with interstitial fluid which
helps in the regulation of water content of the body
REGULATION
OF WATER
BALANCE
• Plasma proteins and hemoglobin act as buffers and help in the regulation of acid-
base balance
REGULATION
OF ACID-BASE
BALANCE
• Because of the high specific heat of blood, it is responsible for maintaining the
thermoregulatory mechanism in the body, i.e. the balance between heat loss and
heat gain in the body
REGULATION
OF BODY
TEMPERATURE
• Blood serves as a readymade source for water, proteins, glucose, sodium and
potassium and these substances are taken from blood during starvation, fluid loss,
electrolyte loss, etc.
STORAGE
FUNCTION
• The white blood cells are responsible for the defense of the body
• Neutrophils and monocytes engulf the bacteria by phagocytosis
• Lymphocytes are involved in development of immunity
• Eosinophils are responsible for detoxification, disintegration and removal of foreign proteins
DEFENSIVE
FUNCTION

10. REFERENCE
• Sembulingam K and Prema Sembulingam, Essentials of Medical
Physiology, Jaypee Brothers Medical Publishers (P) Ltd 2012;
6th edition: Chapter 07, (ISBN 978-93-5025-936-8)