This document contains comprehensive notes on Blood Physiology which includes Detail overview of blood physiology, detailing the fundamental aspects of how blood functions within the human body. It includes:
Overview of Blood Composition: An in-depth look at the various components of blood, incl...
BLOOD
Blood is a specialized bodily fluid that circulates through the arteries, veins, and capillaries of the
circulatory system. It performs several crucial functions in the body, essential for maintaining health and
sustaining life.
It consists of a liquid component called plasma and cellular components known as formed
elements.
Plasma: A pale yellow liquid composed primarily of water (about 90%), along with
proteins, electrolytes, hormones, waste products, and gases.
Formed Elements: Include red blood cells (erythrocytes), white blood cells (leukocytes),
and platelets (thrombocytes). Erythrocytes transport oxygen, leukocytes are involved in
immune responses, and thrombocytes aid in blood clotting.
Blood performs vital functions such as transporting oxygen and nutrients to cells, removing
waste products, regulating pH and body temperature, and defending against pathogens. It is
essential for maintaining homeostasis and supporting overall health and bodily functions.
Composition of Blood
1. Plasma
o Plasma makes up about 55% of blood volume.
o It is a pale yellow, liquid component that consists primarily of water (about 90%)
along with proteins, electrolytes (such as sodium and potassium), hormones,
waste products, and gases (like oxygen and carbon dioxide).
2. Formed Elements
o Formed elements constitute about 45% of blood volume and include:
Red Blood Cells (Erythrocytes):
Function: Transport oxygen from the lungs to tissues and carbon
dioxide from tissues to the lungs.
Structure: Biconcave discs containing hemoglobin, a protein that
binds oxygen.
White Blood Cells (Leukocytes):
Function: Play a key role in the immune response by defending
against pathogens (bacteria, viruses) and foreign substances.
Types: Neutrophils, lymphocytes, monocytes, eosinophils,
basophils.
Platelets (Thrombocytes):
Function: Essential for blood clotting (hemostasis) to prevent
excessive bleeding.
Structure: Small cell fragments involved in forming temporary
plugs in damaged blood vessels.
,Functions of Blood
1. Transportation
o Oxygen and Carbon Dioxide: Red blood cells transport oxygen from the lungs to
tissues and carry carbon dioxide back to the lungs for exhalation.
o Nutrients and Waste Products: Plasma transports nutrients (glucose, amino acids)
absorbed from the digestive system and waste products (urea) to be excreted.
o Hormones: Blood carries hormones produced by endocrine glands to target organs
where they regulate physiological processes.
2. Regulation
o pH Balance: Buffers in blood plasma help regulate and maintain a stable pH in the
body.
o Body Temperature: Blood absorbs and distributes heat throughout the body,
helping to regulate temperature.
o Water Balance: Plasma proteins and electrolytes in blood help maintain osmotic
balance between cells and tissues.
3. Protection
o Immune Response: White blood cells (leukocytes) defend against pathogens by
producing antibodies and engulfing foreign particles.
o Clotting Mechanism: Platelets and clotting factors in blood form clots to seal off
damaged blood vessels and prevent excessive bleeding.
Blood performs several essential functions in the body, crucial for maintaining health and
sustaining life. These functions include:
1. **Transportation of Substances**:
- **Oxygen**: Blood carries oxygen from the lungs (via hemoglobin in red blood cells) to
tissues throughout the body for cellular respiration.
- **Carbon Dioxide**: Blood transports carbon dioxide, a waste product of cellular
metabolism, from tissues back to the lungs for exhalation.
2. **Nutrient Transport**:
- Blood transports nutrients absorbed from the digestive system (such as glucose, amino acids,
and fatty acids) to cells throughout the body for energy production, growth, and repair.
3. **Waste Removal**:
, - Blood carries metabolic waste products (like urea and lactic acid) from cells to organs (such
as kidneys and liver) for excretion from the body.
4. **Regulation of Body Temperature**:
- Blood helps regulate body temperature by absorbing and distributing heat throughout the
body. Blood vessels dilate or constrict to release or conserve heat as needed.
5. **pH Balance Regulation**:
- Blood contains buffers (bicarbonate and phosphate ions) that help maintain a stable pH level
in the body, ensuring proper function of enzymes and metabolic processes.
6. **Immune Function**:
- White blood cells (leukocytes) in blood play a crucial role in the body's immune response by
defending against pathogens (bacteria, viruses, fungi) and foreign substances through
phagocytosis, antibody production, and immune signaling.
7. **Clotting Mechanism**:
- Platelets (thrombocytes) and clotting factors in blood initiate the clotting process (hemostasis)
to seal off injured blood vessels and prevent excessive bleeding.
8. **Hormone Transport**:
- Blood transports hormones produced by endocrine glands to target organs and tissues where
they regulate various physiological processes such as metabolism, growth, and reproduction.
9. **Fluid Balance**:
- Blood helps maintain fluid balance in the body by distributing water and electrolytes (such as
sodium, potassium, and chloride) to cells and tissues and ensuring osmotic equilibrium.
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