· Definition: A group of specialized cells similar in embryonic origin, form and function is called tissue.
· But the term histology was given by a German histologist Mayer 1819.
· Study of tissue is called histology.
· Marcello Malpighi, an Italian scientist established a separate branch for the study of tissues so he is the founder of histology.
· Marcello Malpighi, an Italian scientist established a separate branch for the study of tissues so he is the founder of histology.
· Types of Animal Tissues:
· Depending upon the location and function, animal tissue is divided into the following 4 types:
A. EPITHELIAL TISSUE
· Depending upon the location and function, animal tissue is divided into the following 4 types:
A. EPITHELIAL TISSUE
B. MUSCULAR TISSUE
C. CONNECTIVE TISSUE
D. NERVOUS TISSUE
CONNECTIVE TISSUE
· Connective tissue is originated from the embryonic mesoderm.· It has 3 types of components: cells, fibres and matrix.
a. Cells - they are living components and has large intercellular spaces. They are of various kinds such as fibroblast, adipocyte, macrophages etc.
b. Fibres – these are the non-living components of the tissue which are scattered in between the cells of connective tissue.
· They are of 3 types.
i. Collagen fibres – they are white in colour, formed from collagen protein. They are unbranched, arranged in bundles and inelastic.
ii. Elastic fibres- they are long, straight, branched and elastic. They are made up of elastin fibres.
iii. Reticulate fibres – they are made up of reticulin protein. They are very fine short threadlike branched inelastic and always form a fine network.
· They are of 3 types.
i. Collagen fibres – they are white in colour, formed from collagen protein. They are unbranched, arranged in bundles and inelastic.
ii. Elastic fibres- they are long, straight, branched and elastic. They are made up of elastin fibres.
iii. Reticulate fibres – they are made up of reticulin protein. They are very fine short threadlike branched inelastic and always form a fine network.
c. Matrix or ground substance - it is a ground tissue in which cells and fibres are suspended.
· It is mainly a mixture of carbohydrates and proteins.
· Matrix may be amorphous, transparent, liquid semi-fluid or opaque.
· Connective tissues are widely found throughout the body such as in between different tissues and organs, around the organs and in the form of bone or cartilage and blood.
1. General functions of the Connective tissues:
· They are basically packing and binding tissues, provide a skeletal framework (bone and cartilages).
· Some connective tissues such as adipose tissue synthesize, store and metabolize the fats.
· Blood and lymph transport the various materials (nutrients, respiratory gases, excretory wastes) of the body.
· The areolar tissue protects the body against wounds and infections.
2. Depending upon the kind of matrix and number of fibres present in the connective tissues, they are divided into 3 types:
A. CONNECTIVE TISSUE PROPER
B. SUPPORTING CONNECTIVE TISSUE
C. FLUID CONNECTIVE TISSUE
· It is again divided into loose and dense connective tissue proper.
B. SUPPORTING CONNECTIVE TISSUE
C. FLUID CONNECTIVE TISSUE
A. CONNECTIVE TISSUE PROPER
· Connective tissue proper possesses a soft, gel-like matrix.· It is again divided into loose and dense connective tissue proper.
1. LOOSE CONNECTIVE TISSUE PROPER
· In this type of connective tissue, cells are widely distributed and fibres are loosely woven randomly.
· It is further divisible into the following types: Areolar, Adipose and Reticular tissue.
a. Areolar connective tissue
· It is the simplest and most widely distributed connective tissue found in the animal body.1. Matrix- it is transparent, semi-fluid or gelatinous in which elastic, collagen and reticulate fibres are scattered.
2. Fibres- Collagen fibres are numerous found in the wavy bundle whereas elastic and reticulate fibres are irregularly distributed.
3. Cells- Different types of cells are scattered by leaving the small spaces called areolae. So it is named areolar tissue.
Following types of cells are found in the areolar tissue:
1. Fibroblasts- they are flattened spindle-shaped cells with oval nuclei. They produce fibres. In wounded areas, they effectively seal off the injured part.
1. Fibroblasts- they are flattened spindle-shaped cells with oval nuclei. They produce fibres. In wounded areas, they effectively seal off the injured part.
2. Macrophages or histocytes- they are polymorphic amoeboid cells with kidney-shaped nuclei. They engulf bacteria and other foreign particles.
3. Mast cells –these cells are oval-shaped small and contain granular cytoplasm.
· They produce heparin (anticoagulant) and histamine which causes vasodilation, contraction of smooth muscle and stimulates gastric secretion.
4. Plasma cells- these are small, round or irregular in shape. They produce antibodies.
· Location: they are found in subcutaneous tissue, around muscles, nerve and blood vessels, in the bone marrow and between the lobes or lobules of the glands.
b. Adipose tissue
· It is a modified areolar tissue with a negligible intercellular matrix.
· This tissue contains many oval or spherical adipose cells or adipocytes containing fat granules in them.
· It is a modified areolar tissue with a negligible intercellular matrix.
· This tissue contains many oval or spherical adipose cells or adipocytes containing fat granules in them.
· Adipocyte has an eccentric nucleus.
· Adipocytes are of 2 types – white adipocytes & brown adipocytes.
· Adipocytes are of 2 types – white adipocytes & brown adipocytes.
· White adipocytes contain only one fat droplet in them whereas Brown adipocyte contains many fat droplets. Here fibres are almost indistinguishable.
· Brown fat is present in hibernating animals and newly born human children.
· Location – they are found in the subcutaneous tissue, around the heart, kidney eyeball, in mesenteries, in the bubbler of whales and hump of a camel.
· Location – they are found in the subcutaneous tissue, around the heart, kidney eyeball, in mesenteries, in the bubbler of whales and hump of a camel.
· Functions:
1. Adipose tissue synthesizes stores and metabolizes the fat. So it is the source of reserve energy.
2. It acts as a suck absorber around the kidney, heart and eyeball.
3. It prevents heat loss by forming the insulating layer and shaping the body contour.
1. Adipose tissue synthesizes stores and metabolizes the fat. So it is the source of reserve energy.
2. It acts as a suck absorber around the kidney, heart and eyeball.
3. It prevents heat loss by forming the insulating layer and shaping the body contour.
c. Reticular connective tissue
· This tissue consists of stellate shaped cells whose protoplasmic processes join to form a cellular network.
· This tissue consists of stellate shaped cells whose protoplasmic processes join to form a cellular network.
· They are formed by reticular protein.
· Matrix is mostly found in liquid form in which many cells such as macrophages lymphocytes adipocytes are present.
· Location- they are located in the liver, spleen, lymph node thyroid, tonsil and bone marrow.
Functions
1. It forms the sub-epithelial tissue of the gastrointestinal mucosa.
2. It also forms the supporting framework or stroma of many organs such as the spleen, bone marrow etc
3. They have a defensive function and also play the important role in iron and fat metabolism.
· Matrix is mostly found in liquid form in which many cells such as macrophages lymphocytes adipocytes are present.
· Location- they are located in the liver, spleen, lymph node thyroid, tonsil and bone marrow.
Functions
1. It forms the sub-epithelial tissue of the gastrointestinal mucosa.
2. It also forms the supporting framework or stroma of many organs such as the spleen, bone marrow etc
3. They have a defensive function and also play the important role in iron and fat metabolism.
2. DENSE CONNECTIVE TISSUE PROPER
· This tissue has more fibres than the cells.
· The fibres are regularly or irregularly arranged in the matrix.
· They are of the following types: White fibrous tissue, Tendons & Ligament.
a. White fibrous tissue
· White fibrous tissue is shiny, tough and consists of mainly collagen fibres which are arranged in a bundle.
· White fibrous tissue is shiny, tough and consists of mainly collagen fibres which are arranged in a bundle.
· The rows of fibroblasts are running alongside the bundles of collagen fibre.
· They provide strength, making joints immovable and toughness of tissue.
· It is found in the tendon, some ligaments, sclerotic and Cornea layer of the eye, periosteum of bone, perichondrium of cartilage, pericardium of the heart and dura mater of the brain.
b. Tendon
· They are only formed by the thick bundles of collagen fibres running parallel to each other.
· Function: They join the skeletal muscles to bones.
· They are only formed by the thick bundles of collagen fibres running parallel to each other.
· Function: They join the skeletal muscles to bones.
c. Ligament
· The ligament is mainly made up of irregularly arranged yellow elastic fibres and a few are collagen fibres in which fibroblasts are scattered in between them.
· Function:
· This tissue has remarkable elasticity so it allows stretching of various organs and connects bones to bones and help to hold them together.
· The ligament is mainly made up of irregularly arranged yellow elastic fibres and a few are collagen fibres in which fibroblasts are scattered in between them.
· Function:
· This tissue has remarkable elasticity so it allows stretching of various organs and connects bones to bones and help to hold them together.
· Remember as BoMTy & BoBLy where Tendon connects Muscle to Bone and Ligament connects Bont to bone.
· Note: Arteries of many years mummy have well preserved due to the presence of elastic fibres.
· Sprain is caused by excessively pulling or tearing of ligaments whereas Strain is the tearing of muscles or Tendons.
· Sprain is caused by excessively pulling or tearing of ligaments whereas Strain is the tearing of muscles or Tendons.
B. SUPPORTIVE CONNECTIVE TISSUE
· Connective tissue forms the endoskeleton of vertebrates.· It includes cartilage and bone.
a. CARTILAGE
· It is a soft flexible skeletal tissue.
· It is a soft flexible skeletal tissue.
· The cartilage is enclosed by perichondrium.
· Next to the perichondrium is a layer of chondroblasts which eventually form the chondrocytes.
· Next to the perichondrium is a layer of chondroblasts which eventually form the chondrocytes.
· The chondrocytes are dispersed in the matrix and occur in the fluid-filled spaces called lacunae.
· Each lacuna contains 1- 7 chondrocytes.
· Each lacuna contains 1- 7 chondrocytes.
· Each chondrocyte is a large angular cartilage cell with a distinct nucleus.
· The matrix of the cartilage lacks the blood vessels and hence the exchange of material between chondrocytes and matrix is by diffusion only.
· The matrix has the protein chondrin, chondroitin sulphate proteoglycans and glycosaminoglycans.
· The growth of the cartilage is always from the periphery or unidirectional.
· Functions:
· Cartilage is highly adapted to resist any strain placed upon it.
· The growth of the cartilage is always from the periphery or unidirectional.
· Functions:
· Cartilage is highly adapted to resist any strain placed upon it.
· It acts as a mechanical shock absorber.
· Collagen fibres of cartilage resist any tension which may be imposed on the cartilage.
· Collagen fibres of cartilage resist any tension which may be imposed on the cartilage.
Various Types of cartilages:
· According to the composition of the matrix, cartilages are divided into 4 types: Hyaline, Elastic, Calcified and Fibrous Cartilage.
· According to the composition of the matrix, cartilages are divided into 4 types: Hyaline, Elastic, Calcified and Fibrous Cartilage.
1. Hyaline cartilage
· Matrix is glass-like semitransparent or bluish and has fine collagen fibres.
· They are slightly elastic and compressible.
· Location: These cartilages are located at the end of bones, in the nose, trachea, and bronchus, Larynx, sternum, most of the embryonic skeletons and endoskeleton of elasmobranchs or cartilaginous fishes.
· Functions:
· When they are present in the joint they reduce the friction, form the embryonic skeleton and act as a shock absorber.
· Location: These cartilages are located at the end of bones, in the nose, trachea, and bronchus, Larynx, sternum, most of the embryonic skeletons and endoskeleton of elasmobranchs or cartilaginous fishes.
· Functions:
· When they are present in the joint they reduce the friction, form the embryonic skeleton and act as a shock absorber.
2. Elastic cartilage
· The matrix is semitransparent and contains a network of yellow elastic fibres.
· The matrix is semitransparent and contains a network of yellow elastic fibres.
· So it is highly flexible and they show a quick recovery.
· Location- They are found in the external ear, Eustachian tube, tips of the nose, in the pharynx and epiglottis.
· Functions- They provide the greater elasticity, quick recovery and flexibility
· Location- They are found in the external ear, Eustachian tube, tips of the nose, in the pharynx and epiglottis.
· Functions- They provide the greater elasticity, quick recovery and flexibility
3. Fibrous cartilage
· It consists of bundles of densely packed white collagen fibres embedded in the matrix.
· Location- They are located in the intervertebral disc, pubic symphysis and ligaments capsule of joints.
· Functions- It provides greater tensile strength and a small degree of flexibility and acts as a shock absorber.
· It consists of bundles of densely packed white collagen fibres embedded in the matrix.
· Location- They are located in the intervertebral disc, pubic symphysis and ligaments capsule of joints.
· Functions- It provides greater tensile strength and a small degree of flexibility and acts as a shock absorber.
4. Calcified cartilage
· It is formed by the deposition of calcium carbonate in hyaline cartilage.
· It is very hard and inelastic.
· Location- It is found in the head of the humerus and femur, the vertebrae of the shark.
· Location- It is found in the head of the humerus and femur, the vertebrae of the shark.
b. BONES
· Bone is the hardest tissue of the animal body.
· About 30% of the matrix is composed of organic material consisting chiefly of collagen fibres and 70% is inorganic material bone salts.
· Bone is the hardest tissue of the animal body.
· About 30% of the matrix is composed of organic material consisting chiefly of collagen fibres and 70% is inorganic material bone salts.
· Most of the bone mass, 65%, consists of salts of calcium and phosphate.
· The main constituent is the hydroxyl of apatite.
· Small amount of Na, Mg, K, Cl and F are present.
· Small amount of Na, Mg, K, Cl and F are present.
· The phosphate and carbonates of Ca and Mg give hardness and strength to the bone.
· The matrix contains the protein ossein.
Periosteum and Endosteum
· Bone is enclosed in the thick, tough sheath of white fibrous connective tissue with fibroblast called the periosteum.
· These bundles of collagen fibres are called Sharpey's fibres that penetrate the bone matrix and bind the periosteum to the bone.
· Bone is enclosed in the thick, tough sheath of white fibrous connective tissue with fibroblast called the periosteum.
· These bundles of collagen fibres are called Sharpey's fibres that penetrate the bone matrix and bind the periosteum to the bone.
· Endosteum is the innermost layer that lines the internal cavity of bone which contain a thin layer of osteoprogenitor cells and a very small amount of connective tissue.
· Bone lamellae: In the bone, the matrix is arranged in the concentric circle called lamellae.
· Bone lacunae: Between the lamellae number of living bone cells called osteoblasts or osteocytes are present in the fluid-filled space or cavity called lacunae.
· Osteoblasts are active bone cells whereas osteocytes are inactive bone cells.
· Osteoblasts are responsible for the synthesis of the organic components and deposition of the inorganic compounds in the bone matrix.
· Osteoblasts are exclusively located at the surface of the bone.
· They may be a cuboidal or columnar shape with basophilic cytoplasm.
· Each lacuna has fine cytoplasmic processes called canaliculi which pass through the lamellae and make connections with other lacunae and Haversian canal.
· Each lacuna has fine cytoplasmic processes called canaliculi which pass through the lamellae and make connections with other lacunae and Haversian canal.
Haversian canal:
· Each Haversian canal contains an artery; a vein, a lymph vessel, nerve fibres and some bone cells where all packed in connective tissue.
· A Haversian canal with surrounding lamellae and osteocytes constitute a cylindrical unit of bone called the Haversian canal system or Osteon.
· Each Haversian canal contains an artery; a vein, a lymph vessel, nerve fibres and some bone cells where all packed in connective tissue.
· A Haversian canal with surrounding lamellae and osteocytes constitute a cylindrical unit of bone called the Haversian canal system or Osteon.
· This system is absent in the spongy bones of mammals.
· The Haversian canals are interconnected by transverse channels called Volkmann’s canals.
· The Haversian canals are interconnected by transverse channels called Volkmann’s canals.
Various Types of Bone:
A. On the basis of its texture or matrix present in it, bones are divided into 2 types:
1. Compact or dense or Periosteal bone
2. Cancellous or spongy or Trabecular bone
2. Cancellous or spongy or Trabecular bone
1. Compact bone
· The matrix of the compact bone is solid hard and dense without any spaces between the lamellae. Hence it is also called compact bone.
· The matrix of the compact bone is solid hard and dense without any spaces between the lamellae. Hence it is also called compact bone.
· It forms the shaft or diaphysis of the bone.
· It is filled with a fatty tissue called yellow bone marrow.
· This yellow bone marrow stores the fat cells. It has a number of Haversian canals system
2. Spongy bone
· It consists of small pieces of bone called trabeculae that are joined together irregularly by living the spaces in between them.
· It consists of small pieces of bone called trabeculae that are joined together irregularly by living the spaces in between them.
· It forms the expanded end or epiphysis of the long bone.
· Spongy bone contains red bone marrow to produce the red blood cells and it lacks the Haversian canal system.
B. On the basis of origin and development, the bones are grouped into these types:
1. Membrane bone or investing bone or dermal bone
· These bones are developed in the dermis of skin as thin plates and sink to get attached over the original cartilaginous endoskeleton.
· Finally they form investment over the original cartilage and provide the rigidity to them.
· Examples- Frontal, nasal, parietal bones of the skull are examples of this type of bone.
· Examples- Frontal, nasal, parietal bones of the skull are examples of this type of bone.
2. Cartilaginous or replacing bone
· These bones develop from the pre-existing cartilage which is gradually replaced by the bone.
· They are also known as the endochondral bones.
· Example- All the long bones of the body such as the femur and humerus
· Example- All the long bones of the body such as the femur and humerus
3. Visceral bone
· These bones are developed in the soft organs.
· These bones are developed in the soft organs.
· For example, os cardis in the heart of ruminants or deer, Os penis or baculum in the penis of most of the bats.
4. Sesamoid bones
· These bones are formed in the tendons at joints.
· Example- Patella.
Ossification:
· Bone is formed by two processes:
1. Intramembranous ossification
1. Intramembranous ossification
2. Endochondral ossification
1. Intramembranous ossification: Here bone is formed by the osteoblasts.
· Eg- frontal, parietal, occipital, and temporal bone.
2. Endochondral ossification: Bone is formed by the deposition of minerals in the hyaline cartilage.
· Example- long and short bone of the body.
Notes:
· Osteoclast or Bone Destroying cells: They are derived from the osteoblasts or osteocytes which destroy the bone matrix.
· Osteomyelitis: It is the inflammation of bone marrow or adjacent bone or cartilage.
· Pagers disease: It is the irregular thickening or softening of bones.
· Osteomyelodysplasia: It is the enlargement of bone marrow cavities or thinning of osseous tissue large thin-walled vascular space and leucopenia and irregular fever
· Osteoclast or Bone Destroying cells: They are derived from the osteoblasts or osteocytes which destroy the bone matrix.
· Osteomyelitis: It is the inflammation of bone marrow or adjacent bone or cartilage.
· Pagers disease: It is the irregular thickening or softening of bones.
· Osteomyelodysplasia: It is the enlargement of bone marrow cavities or thinning of osseous tissue large thin-walled vascular space and leucopenia and irregular fever
C. Vascular tissue or Fluid Connective Tissue
· Vascular tissues are the motile connective tissue consisting of fluid matrix and free cell.· Matrix has no fibres.
· This tissue consists of both myeloid and lymphoid tissue which forms blood and lymph respectively.
· This tissue consists of both myeloid and lymphoid tissue which forms blood and lymph respectively.
1. Blood
· Study of blood is called haematology.
· It covers 8% of total body weight.
· It is the softest tissue of an animal’s body.
· They are referred to as the seat of soup.
· It is salty in taste and slightly alkaline having a pH of 7.4 to arteries but more than this in vein.
· It is derived from the embryonic mesoderm.
· Osmotic pressure is equivalent to 7-8 atm. Pressure.
· Blood is made up of 2 principal components:
· Study of blood is called haematology.
· It covers 8% of total body weight.
· It is the softest tissue of an animal’s body.
· They are referred to as the seat of soup.
· It is salty in taste and slightly alkaline having a pH of 7.4 to arteries but more than this in vein.
· It is derived from the embryonic mesoderm.
· Osmotic pressure is equivalent to 7-8 atm. Pressure.
· Blood is made up of 2 principal components:
· A watery fluid matrix called plasma and floating bodies are termed as formed elements or blood corpuscles.
2. Plasma
· Plasma is a straw colour solution and non-living intercellular substance which constitutes about 55% of the total volume of blood.
· Composition of plasma
· Plasma contains the following components:
· Water- about 90-92%
· Plasma protein- about 7%
· Inorganic compound -1%
· Organic compound- 1-2%
· Plasma is a straw colour solution and non-living intercellular substance which constitutes about 55% of the total volume of blood.
· Composition of plasma
· Plasma contains the following components:
· Water- about 90-92%
· Plasma protein- about 7%
· Inorganic compound -1%
· Organic compound- 1-2%
· Blood plasma has three types of proteins:
1. Serum albumin (4.7%): It maintains the osmotic concentration of the blood and binds the lipid, hormones and retain water.
2. Serum globulin (1.5%): It binds to iron, vitamins A, D, E, K and acts as antibodies.
3. Fibrinogen (0.3%): It helps in blood clotting.
· Many others products are present in blood in varying concentrations. They are products of digestion, excretory products, vitamins, hormones, respiratory gases, germs and bacteria, anticoagulant substances etc.
Functions of blood plasma:
· Albumin is a main component of plasma and has a fundamental role in maintaining the osmotic pressure of blood.
· Gamma globins are immunoglobins that produce antibodies.
· Alpha and beta globulins bind with thyroxin, bilirubin, iron, vitamin A, D, E, K and cholesterol.
· Fibrinogen is necessary for blood clotting.
· Plasma protein transports the nutrients and maintains the pH of the blood.
· Plasma also conducts the heat to skin for the dissipation of heat uniformly all over the body.
· Plasma transports the main substances to and fro in the body such as digested food, excretory wastes products, respiratory gases, hormones.
1. Serum albumin (4.7%): It maintains the osmotic concentration of the blood and binds the lipid, hormones and retain water.
2. Serum globulin (1.5%): It binds to iron, vitamins A, D, E, K and acts as antibodies.
3. Fibrinogen (0.3%): It helps in blood clotting.
· Many others products are present in blood in varying concentrations. They are products of digestion, excretory products, vitamins, hormones, respiratory gases, germs and bacteria, anticoagulant substances etc.
Functions of blood plasma:
· Albumin is a main component of plasma and has a fundamental role in maintaining the osmotic pressure of blood.
· Gamma globins are immunoglobins that produce antibodies.
· Alpha and beta globulins bind with thyroxin, bilirubin, iron, vitamin A, D, E, K and cholesterol.
· Fibrinogen is necessary for blood clotting.
· Plasma protein transports the nutrients and maintains the pH of the blood.
· Plasma also conducts the heat to skin for the dissipation of heat uniformly all over the body.
· Plasma transports the main substances to and fro in the body such as digested food, excretory wastes products, respiratory gases, hormones.
Blood corpuscles or Formed elements:
· The cellular elements are slightly heavier than plasma, constituting nearly 45% of the total volume of blood.
· The cellular elements are slightly heavier than plasma, constituting nearly 45% of the total volume of blood.
· Formed elements are of the following types:
1. Erythrocytes or Red blood corpuscles (RBCs)
· It was first described by Swammerdam in 1658.
· Erythrocytes are non-nucleated in mammals except Camel and Llamas which contain haemoglobin in their cytoplasm.
· In fishes, amphibians, reptiles and birds, they are biconvex and oval in shape but in mammals, they are biconcave and circular with an average diameter of 6-9 microns.
· RBCs of amphibians (Amphiuma and Proteus) are the largest among all vertebrates (80 millimicrons in diameter) whereas mammalian RBCs are the smallest (musk deer).
· They are produced (by erythropoiesis) in the bone marrow of ribs, vertebrae and skull in adults and in the yolk sac(in early life) and liver (in middle foetal life).
· They look pale yellow in colour in the single state when viewed in bulk they are red in colour.
· It was first described by Swammerdam in 1658.
· Erythrocytes are non-nucleated in mammals except Camel and Llamas which contain haemoglobin in their cytoplasm.
· In fishes, amphibians, reptiles and birds, they are biconvex and oval in shape but in mammals, they are biconcave and circular with an average diameter of 6-9 microns.
· RBCs of amphibians (Amphiuma and Proteus) are the largest among all vertebrates (80 millimicrons in diameter) whereas mammalian RBCs are the smallest (musk deer).
· They are produced (by erythropoiesis) in the bone marrow of ribs, vertebrae and skull in adults and in the yolk sac(in early life) and liver (in middle foetal life).
· They look pale yellow in colour in the single state when viewed in bulk they are red in colour.
· Red colour is due to the presence of haemoglobin in them.
· Haemoglobin is the complex chromoprotein consisting of two alpha chains with 14 aminoacids each and two beta–chains with 46 amino acids each.
· 100ml of blood contains 15gm haemoglobin.
· An adult who has less than 12gm of haemoglobin is called anaemic.
· Haemoglobin constitutes about 33% of RBC.
· RBC production is controlled by glycoprotein hormone called erythropoietin secreted by the kidney in response to insufficient oxygen.
· When RBCs adhere together by their concave surfaces like a pile of coins. It is called rouleaux – formation.
· If the RBCis kept in distilled water or hypotonic solution the RBC bursts the phenomenon is called haemolysis.
· When the blood is kept in 8% NaCl solution or hypertonic solution the RBC Shrink.
· Isotonic solution with blood is 0.9% NaCl solution, saline.
· Haematocytometer is an instrument used to count the number of RBCs.
· Packed cell volume or haematocrit is the volume of red blood cells in 1 litre or 100Ml of whole blood, which is estimated using a Wintrobe tube.
· A normal increment of RBCs is called polycythemia.
· Almost the entire cytoplasm is filled with haemoglobin, so they have no cell organelles (nucleus, mitochondria, ER, Ribosomes and Golgi bodies).
· Due to the absence of mitochondria, they respire anaerobically.
· RBC loses nucleus at reticulocyte stage.
· Haemoglobin is a conjugated protein, formed by the 4 non-protein group haem and 4 protein globin molecules.
· A single RBC has 28 million haemoglobin molecules.
· A normal adult man and women have 5 and 4.5 million RBCs per cubic millimetre of blood respectively. The quantity of RBC is less in women as they undergo menstruation.
· The average life span of RBC is about 120 days in mammals and 100 days in frogs. After then they are disposed of either by liver or spleen.
· Spleen is the chief site of disposal. So they are called graveyards where they decomposed into haem and globin parts.
· Iron of haem is released into the blood which is again utilized in the synthesis of fresh RBCs and some part of it is transformed into bilirubin in the liver which is excreted from the bile as bile pigment.
· Globin part of RBC is used for the repairment and growth of the cell.
· The process of formation of RBCs is called erythropoiesis. The mother cell of RBC is nucleated erythroblast.
· An abnormal rise in the number of RBCs is called polycythemia whereas the decrease in the number of RBCs is called Erythrocytopenia which causes oxygen shortage in blood and tissues.
· Any condition that leads to the destruction of RBCs which finally reduce the haemoglobin content in the blood by below 70% is called anaemia.
· Hamatocytoblast is the red bone marrow that gives rise to mature RBCs.
· Haemoglobin is the complex chromoprotein consisting of two alpha chains with 14 aminoacids each and two beta–chains with 46 amino acids each.
· 100ml of blood contains 15gm haemoglobin.
· An adult who has less than 12gm of haemoglobin is called anaemic.
· Haemoglobin constitutes about 33% of RBC.
· RBC production is controlled by glycoprotein hormone called erythropoietin secreted by the kidney in response to insufficient oxygen.
· When RBCs adhere together by their concave surfaces like a pile of coins. It is called rouleaux – formation.
· If the RBCis kept in distilled water or hypotonic solution the RBC bursts the phenomenon is called haemolysis.
· When the blood is kept in 8% NaCl solution or hypertonic solution the RBC Shrink.
· Isotonic solution with blood is 0.9% NaCl solution, saline.
· Haematocytometer is an instrument used to count the number of RBCs.
· Packed cell volume or haematocrit is the volume of red blood cells in 1 litre or 100Ml of whole blood, which is estimated using a Wintrobe tube.
· A normal increment of RBCs is called polycythemia.
· Almost the entire cytoplasm is filled with haemoglobin, so they have no cell organelles (nucleus, mitochondria, ER, Ribosomes and Golgi bodies).
· Due to the absence of mitochondria, they respire anaerobically.
· RBC loses nucleus at reticulocyte stage.
· Haemoglobin is a conjugated protein, formed by the 4 non-protein group haem and 4 protein globin molecules.
· A single RBC has 28 million haemoglobin molecules.
· A normal adult man and women have 5 and 4.5 million RBCs per cubic millimetre of blood respectively. The quantity of RBC is less in women as they undergo menstruation.
· The average life span of RBC is about 120 days in mammals and 100 days in frogs. After then they are disposed of either by liver or spleen.
· Spleen is the chief site of disposal. So they are called graveyards where they decomposed into haem and globin parts.
· Iron of haem is released into the blood which is again utilized in the synthesis of fresh RBCs and some part of it is transformed into bilirubin in the liver which is excreted from the bile as bile pigment.
· Globin part of RBC is used for the repairment and growth of the cell.
· The process of formation of RBCs is called erythropoiesis. The mother cell of RBC is nucleated erythroblast.
· An abnormal rise in the number of RBCs is called polycythemia whereas the decrease in the number of RBCs is called Erythrocytopenia which causes oxygen shortage in blood and tissues.
· Any condition that leads to the destruction of RBCs which finally reduce the haemoglobin content in the blood by below 70% is called anaemia.
· Hamatocytoblast is the red bone marrow that gives rise to mature RBCs.
Functions of RBCs:
· It transports the respiratory gases, acts as a buffer system by maintaining the pH and viscosity of blood.
· It transports the respiratory gases, acts as a buffer system by maintaining the pH and viscosity of blood.
Types of Anaemia and Causative Factors:
| Microcytic anaemia | Deficiency of iron |
| Megaloblastic anaemia | Deficiency of folic acid and Vit- B12 |
| Pernicious anaemia | Deficiency of B12 |
| Haemorrhagic anaemia | Excessive bleeding |
| Haemolytic anaemia | Haemolysis or rupture of RBCs |
| Aplastic anaemia | Destruction of bone marrow |
| Nutritional anaemia | Inadequate nutrients |
| Sickle–cell anaemia | Gene mutation |
| Thalassemia | Gene mutation |
| septicemia | Blood poisoning |
2. Leucocytes or white blood corpuscles (WBCs)
· These are colourless blood corpuscles because they do not have any pigments in their structure.
· They are round or irregular in shape and capable of amoeboid movement.
· Their size is from 12-20 micrometres so they are larger than RBC. They can be squeezed out from blood capillaries due to amoeboid movement (diapedesis).
· They are formed in the red bone marrow and in the lymph glands. The total number of WBC or total leucocytes count (TLC) is about 5000-10000/mm3. They are present in much smaller numbers than RBC their ratio to RBC is 1:600. The life span of human WBC is about 12-13 days.
· Leucocytosis refers to an increase in the number of WBCs.
· Leucopenia is an abnormally low level of WBCs.
· Differential leucocytes count (DLC) is the number of each kind of leucocyte in 100 WBCs.
· They are formed in the red bone marrow and in the lymph glands. The total number of WBC or total leucocytes count (TLC) is about 5000-10000/mm3. They are present in much smaller numbers than RBC their ratio to RBC is 1:600. The life span of human WBC is about 12-13 days.
· Leucocytosis refers to an increase in the number of WBCs.
· Leucopenia is an abnormally low level of WBCs.
· Differential leucocytes count (DLC) is the number of each kind of leucocyte in 100 WBCs.
Normal DLC:
| Neutrophils | 60 | 70 % |
| Eosinophils | 2 | 4 % |
| Basophils | 0.5 | 1 % |
| Monocytes | 3 | 8 % |
| lymphocytes | 20 | 25 % |
Various Types of WBCs:
· WBCs have been divided into 2 main types: Agranulocytes & Granulocytes.
A. Agranulocytes:
· They have no granules in their cytoplasm.
· Their nuclei are simple without any lobes.
· Hence they are also called mononuclear leucocytes.
· Agranulocytes are divided into 2 types: Lymphocytes & monocytes.
· Agranulocytes are divided into 2 types: Lymphocytes & monocytes.
i. Lymphocytes
· They are the smallest leucocytes and has a large rounded nucleus.
· They are the smallest leucocytes and has a large rounded nucleus.
· They are less motile and non-phagocytic.
· They produce antibodies to destroy microbes and their toxins grafts and kill the tumour cells and help in the healing of injuries.
· It constitutes 20-50% of total WBCs.
· They are functionally two types: T- lymphocytes and B- lymphocytes.
· They are functionally two types: T- lymphocytes and B- lymphocytes.
ii. Monocytes
· They are the largest of all types of WBCs.
· They are the largest of all types of WBCs.
· Their nucleus is bean-shaped and has much cytoplasm.
· They are motile and phagocytic in nature and engulf bacteria and cellular debris.
· They can change their shape into tissue spaces as different forms.
· Examples of Various Monocytes are:
B. Granulocytes
- Histiocyte in connective tissue
- Microglicytes in nervous tissue
- Kupffer cell in the liver
- Alveolar macrophage or dust cell in alveoli of lungs
- Macrophages in lymph node spleen and bone marrow.
- Osteoclasts in bone.
· Their cytoplasm is granular and nuclei are large and irregular in shape with lobes.
· Hence these are called polymorphonuclear leucocytes.
· They are produced in the bone marrow.
· They are also 3 types: Eosinophils or acidophils, Basophil & Neutrophils or Heterophils.
I. Eosinophils or Acidophils
· They are stained with acidic dyes such as eosin.
· They have 2 lobed nuclei.
· They are 10-15 microns in diameter, constitute 1-4% of total leucocytes count.
· They destroy and detoxify the toxins of protein origin.
· They also help in dissolving the blood clot.
· Their increased number in the human body causes a disease called eosinophilia.
II. Basophil
· Their cytoplasmic granules take basic or blue stains.
· Their cytoplasmic granules take basic or blue stains.
· Nucleus is 3 lobed.
· They are 10-15 microns in diameter.
· These are about 0.4% of the total WBC count (the least common type of leucocyte).
· They produced histamine and heparin.
· When stained with basic dyes such as toluidine blue the granules in the basophil bind the dye and colour changes to red this phenomenon is called metachromasia.
III. Neutrophils or Heterophils
· They are neutral in nature in case of basicity and acidity.
· They are neutral in nature in case of basicity and acidity.
· Their nucleus has many lobes.
· They are the most numerous of all leucocytes (50-70%) and are about 12-15 microns in diameter.
· They are phagocytic in nature.
· The granulocytes remain alive for 1-4 days while agranulocytes remain alive from some days to months.
· In 3% neutrophil of females, the condensed inactive x- chromosome or Barr body exists in the form of a drumstick.
· In 3% neutrophil of females, the condensed inactive x- chromosome or Barr body exists in the form of a drumstick.
· Defunct neutrophils are the main cellular constituent of pus
· Therefore referred to as pus cell.
· They stimulate the production of interferons, antiviral substances.
· Notes:
· Leucocytosis: During all the infections of the body, the number of granular leucocytes is increased in the blood. This condition is called leucocytosis.
· Leukaemia or blood cancer: It is an abnormal uncontrolled increase in the leucocytes numbers.
· Leucopenia: It is the abnormal damage and fall of leucocytes below 4000/mm3. It could be as a result of starvation, medicine or folic acid deficiency.
· Therefore referred to as pus cell.
· They stimulate the production of interferons, antiviral substances.
· Notes:
· Leucocytosis: During all the infections of the body, the number of granular leucocytes is increased in the blood. This condition is called leucocytosis.
· Leukaemia or blood cancer: It is an abnormal uncontrolled increase in the leucocytes numbers.
· Leucopenia: It is the abnormal damage and fall of leucocytes below 4000/mm3. It could be as a result of starvation, medicine or folic acid deficiency.
3. Thrombocytes or Blood platelets
· These are small colourless, flat or spindle-shaped, nucleated bodies, even smaller than RBC.
· They are 2-3 microns in diameter.
· They are fragments of protoplasm broken from or separated from the large bone marrow cells called megakaryocytes.
· The formation of thrombocytes is called thrombopoiesis.
· Due to successive endomitosis megakaryocytes exhibit polyploidy (16-64n)
· Their number is about 2500/mm3.
· Due to successive endomitosis megakaryocytes exhibit polyploidy (16-64n)
· Their number is about 2500/mm3.
· Their life span is about a week.
· They are the source of thromboplastin, therefore necessary for blood clotting.
· They are the source of thromboplastin, therefore necessary for blood clotting.
· Functions:
· When the blood vessels are damaged, platelets release certain chemicals which are called thromboplastin or platelets factor.
· When the blood vessels are damaged, platelets release certain chemicals which are called thromboplastin or platelets factor.
· This thromboplastin helps in blood clotting.
· A sharp decrease in the number of thrombocytes is called thrombopenia.
· Eosinophil has receptor IgE which may be important in the destruction of parasites.
· Its number increased during allergic conditions such as asthma and hay fever.
· A sharp decrease in the number of thrombocytes is called thrombopenia.
· Eosinophil has receptor IgE which may be important in the destruction of parasites.
· Its number increased during allergic conditions such as asthma and hay fever.
Haemopoiesis:
· The process of formation of blood is called haemopoiesis and tissues which form the blood corpuscles in the vertebrates are called haemopoietic tissues.
· Haemopoietic tissues are not definite in different vertebrates.
· The process of formation of blood is called haemopoiesis and tissues which form the blood corpuscles in the vertebrates are called haemopoietic tissues.
· Haemopoietic tissues are not definite in different vertebrates.
· In frogs, the spleen, liver, lymph nodes are the main sites of haemopoiesis.
· In the tadpole stage, the kidney also is haemopoietic tissue.
· In mammalian embryos, the yolk sac, liver, bone marrow, and thymus are haemopoietic tissues while in adults, spleen and red bone marrow are the haemopoietic tissues.
· In mammalian embryos, the yolk sac, liver, bone marrow, and thymus are haemopoietic tissues while in adults, spleen and red bone marrow are the haemopoietic tissues.
Lymph:
· Lymph is a clear opalescent, alkaline fluid in the vessels of the lymphatic system.
· Lymph is blood minus RBCs.
· Lymph is a clear opalescent, alkaline fluid in the vessels of the lymphatic system.
· Lymph is blood minus RBCs.
· It comprises lymph plasma and lymph corpuscles or cells.
· Most important centre for the formation of lymph is interstitial space.
· Lymph vessels in the intestinal villi are called lacteals.
· Most important centre for the formation of lymph is interstitial space.
· Lymph vessels in the intestinal villi are called lacteals.
Lymph plasma:
· It is similar in blood but has fewer blood proteins, less Ca, P and high glucose concentration.
· It is similar in blood but has fewer blood proteins, less Ca, P and high glucose concentration.
· Mainly globulin proteins are present in lymph plasma.
· It also contains organic, inorganic and water.
Lymph corpuscles or cells
· These are floating amoeboid cells leucocytes chiefly lymphocytes.
· These are floating amoeboid cells leucocytes chiefly lymphocytes.
· The erythrocytes and platelets are absent in the lymph.
· They are produced from lymph nodes, tonsils, spleen, liver and thymus glands.
Functions of lymph:
· Body cells are kept moist by lymph.
· It destroys the microorganisms and foreign particles in the lymph nodes.
· It acts as a middle man which transports the oxygen hormones and food materials to the tissues and metabolic wastes carbon dioxide from cells to blood and finally into the venous system.
· It absorbs and transports the fat and fat-soluble vitamins from the intestine through lacteals.
· It brings plasma protein from liver cells and hormones from endocrine glands into the blood.
· It maintains the blood volume. When blood volume reduces in the vascular system.
· Body cells are kept moist by lymph.
· It destroys the microorganisms and foreign particles in the lymph nodes.
· It acts as a middle man which transports the oxygen hormones and food materials to the tissues and metabolic wastes carbon dioxide from cells to blood and finally into the venous system.
· It absorbs and transports the fat and fat-soluble vitamins from the intestine through lacteals.
· It brings plasma protein from liver cells and hormones from endocrine glands into the blood.
· It maintains the blood volume. When blood volume reduces in the vascular system.
Also, Read our Other Notes Related to Animal Tissues: