Animal tissues.pdf

Animal tissues By: Mr. Levine Dave N. Nacino, LPT  tissue A group of cells with similar structure and function. Histology – the study of tissues. Histopathology - study of tissues in connection with diseases of tissues. The word tissue is derived from a Latin...

Animal tissues By: Mr. Levine Dave N. Nacino, LPT  tissue A group of cells with similar structure and function. Histology – the study of tissues. Histopathology - study of tissues in connection with diseases of tissues. The word tissue is derived from a Latin word which means 'weave'. animal tissues  Epithelial tissues Epithelial tissue is made of closely-packed cells arranged in flat sheets. It is a type of animal tissue that covers the body and lines the body’s cavities and organs. Ex. Skin 3 Main Functions: 1. Protection 2. Secretion 3. Absorption  2 parts of the epithelial tissue The apical surface is exposed to the body cavity or exterior. The basal surface is adjacent to the underlying tissue.  2 general types of epithelial tissues Simple epithelium - is composed of single layer of cells. It functions as a lining of cavities of body, ducts and tubes. Stratified epithelium - is made of two or more cell layers. It functions as a protective covering, like it does in our skin. 3 types of epithelial tissues according to shape  Functions of simple epithelium Main functions: 1. Nutrient, water, and electrolyte absorption 2. Secretion of mucus (digestive tract) and secretion of hormones (thyroids and pancreas) 3. Blood filtration 4. Gas diffusion in the alveoli 5. Sensation (taste buds and olfactory epithelium)  simple Squamous epithelium It is made of a single layer of irregular, thin, flattened cells with irregular boundaries. They are found in the walls of blood vessels and in air sacs of lungs. They are involved in functions like forming a diffusion boundary. Blood vessels: Air sacs: Reduction of friction Gas exchange  Blood vessel simple squamous epithelium  Simple Cuboidal epithelium It is made of a single layer of cube-like cells. They are commonly found in: - Ducts of glands - Tubules of nephrons, and - Ovary Its main functions are secretion and absorption.  Kidney simple cuboidal epithelium  Simple columnar epithelium The simple columnar epithelium is composed of single layer of tall and slender cells. The free surface of these cells may have microvilli. They are found in lining of stomach and intestine. It helps in secretion and absorption. Goblet cells is a column-shaped cell which function is to secrete mucus in order to protect the mucous membranes where they are found.  kidney Simple columnar epithelium  CILIATED columnar epithelium It is composed of tall, column-shaped cells. Each cell typically has a single, oval nucleus located near the base. It is found in the respiratory tract, fallopian tubes, vas deferens and the brain. mucociliary escalator – movement of mucus and trapped particles upward toward the throat, preventing them from reaching the lungs It has cilia that beats in a coordinated manner to move substances along the surface of the tissue. Ciliated columnar epithelium  PSEUDOSTRATIFIED CILIATED columnar epithelium A type of epithelial tissue that appears to be composed of multiple layers of cells, but in reality, it is a single layer. The nuclei of the cells are positioned at different levels, giving the illusion of stratification, but each cell is connected only at a single basement membrane. It has the same functions as the ciliated columnar epithelium (found in the respiratory tract and reproductive parts). This is a tissue that lines up the nasal cavity to filter and clean the air we inhale.  Pseudostratified ciliated columnar epithelium Functions of stratified epithelium Main functions: 1. Provide protection against stress (mechanical, abrasion, and damage) 2. Protection against infections. 3. Regeneration and repair (shedding and emergence of new cells) 4. Cover dry surface of skin, moist surface of buccal cavity, pharynx, and inner lining of salivary glands.  STRATIFIED SQUAMOUS EPITHELIUM This is the most common type of stratified epithelium. The basal cells are typically cuboidal or columnar and undergo constant division. As new cells are produced, older cells are pushed toward the surface, where they flatten and become squamous (thin and flat). The apical layer consists of squamous cells, which can be either keratinized or non-keratinized.  Keratinized Stratified Squamous Epithelium Function: Provides protection against abrasion, desiccation, and microbial invasion. Location: Found in the epidermis of the skin. The surface cells are filled with keratin, a tough, fibrous protein that makes the epithelium water-resistant and more durable. The outermost cells are dead and constantly shed and replaced.  Non-Keratinized Stratified Squamous Epithelium Function: Protects against abrasion and provides a moist surface that reduces friction. Location: Lines moist surfaces such as the oral cavity, esophagus, vagina, and the lining of the mouth and throat. The surface cells remain alive and do not become keratinized, maintaining a moist environment.  STRATIFIED CUBOIDAL EPITHELIUM This type of epithelium consists of two or more layers of cells, where the cells in the apical layer are cuboidal in shape It is less common than stratified squamous epithelium. Function: Provides protection and limited secretion and absorption. Location: Found mainly in the ducts of some larger glands, such as sweat glands, mammary glands, and salivary glands. It provides a sturdy lining for these ducts, protecting the underlying tissues.  STRATIFIED columnar EPITHELIUM This type of epithelium consists of several cell layers, with the apical layer being composed of columnar cells. The deeper layers may be cuboidal or irregular in shape. It is relatively rare in the body. Function: Provides protection and secretion. Location: Found in specific areas such as the male urethra, the conjunctiva of the eye, and in some large ducts of glands like the salivary glands. It also lines parts of the pharynx and the epiglottis, where it helps protect these tissues and facilitates the passage of materials.  Connective tissues Connective tissues are all characterized by the presence of extracellular matrix. The extracellular matrix is nonliving material composed of protein fibers and ground substance. Ground substance is a gel-like material that occupies the space between the cells and fibers in connective tissues. The protein fibers are composed of collagen (which gives strength) or elastin (which gives flexibility). Main functions: binding, supporting, protecting ,forming blood, storing fats, and filling space. Extracellular matrix  3 main types of connective tissue 1. Connective Tissue Proper - Loose Connective Tissues - Dense Connective Tissues 2. Supportive Connective Tissue - Cartilage - Bone 3. Fluid Connective Tissue - Plasma - Blood Glucose - Blood Cholesterol - Blood Cells Connective tissue proper  loose connective tissue It consists of cells scattered within an amorphous mass of proteins that forms a ground substance. The gelatinous material is strengthened by loose scattering of protein fibres such as collagen, elastin, and reticulin which makes tissue elastic.s  Adipose tissue These are the fat storing tissues which stores fat for emergency conditions. Hence they are also called the fat cells or adipocytes. - skin, kidney and bone-marrow Main Functions: - Synthesis, storage and metabolism of fat - Prevents heat loss - Shock absorbent - Food reserves  Areolar tissues It occurs beneath the epithelia of many hollow visceral organs, skin and in the walls of arteries and veins. It joins different tissues and forms the packing between them and helps to keep the organs in place and in normal shape. Cells: -Fibroblast -Macrophage -Mast Cells -Plasma Cells  fibroblast The principal cells of areolar tissues. These produces two types of proteins; collagen and elastin. It also secrete the major amount of matrix.  macrophage It is also called histiocytes or clasmatocytes. These are phagocytic in nature i.e. they eat up the bacteria and other foreign bodies that enter our body.  Mast cell It is also called mastocytes. These produces anti-allergic substances like histamine, heparin and serotonin in case of allergies.  Plasma cells They are specialized white blood cells (a type of B cell) that play a crucial role in the immune system. Their primary function is to produce and secrete large amounts of antibodies. Antibodies - large variety of proteins normally present in the body or produced in response to an antigen which it neutralizes, thus producing an immune response. Antigen – any foreign substance (toxin, enzyme, bacteria or virus) that stimulates an immune response in the body (the production of antibodies).  Dense connective tissue The fibres are closely packed in dense connective tissues which includes the following: - White fibrous tissues - Tendons - Ligaments - Reticular tissues  White fibrous tissue It carries only a few fibroblasts scattered at the middle of the dense network of thick collagen fibre bundles. The presence of white fibrous tissues at the joints between skull bones makes them immovable.  tendons It is a very dense, strong and fibrous connective tissue with thick parallel bundles of collagen fibres. Tendon forms the strong inextensible attachment of a skeletal muscle to a bone.  ligaments These connects bones at the joints and hold them in position. They are made up of bundles of elastic fibres and few collagen fibres.  Reticular tissues It consists of star shaped reticular cells whose protoplasmic processes form a network. These cells are present at the spleen, lymph nodes, bone marrows etc. It gives support to lymphoid organs. Supportive connective tissue  cartilage It is a solid but semi-rigid and flexible connective tissue. They occur in cluster of 2 or 3 cells in small spaces scattered in the matrix. Types of Cartilage - Hyaline Cartilage - Elastic Cartilage - Calcified Cartilage  Types of cartilage Hyaline cartilage: In this, the matrix is fibreless and glass like but translucent. It occurs in the larynx, nasal septum, tracheal rings and ribs. It gives these structures a definite form. Elastic cartilage: These contains dense network of elastic fibres. It is present in the Eustachian tube, epiglottis and pinna of ear. The elastic fibres make those organs elastic and pliable. Calcified cartilage: Initially it is like hyaline cartilage but later on it gets hardened like bone due to deposition of calcium salts. e.g. femur and humerus, epiphyseal plate (growth plates)  bone It is a solid, rigid connective tissue. The matrix of the bone has the deposition of apatite salts of calcium and phosphates. Osteoblasts are the bone forming cells. Osteoclasts are cells responsible for the breakdown of bones, including resorption of bone tissue. Osteocytes are bone cells. Bones gives the basic structure of our body and together all the bones constitutes the skeleton.  Types of bones Cartilage bones or Endochondral or Replacing Bones They are formed by the replacement of cartilage by the bones like humerus, femur, vertebrae etc.  Types of bones Membrane / Investing / Dermal bone: These bones are formed in the dermis of the skin and are invested over the already present cartilage like skull bones.  Types of bones Sesamoid bones They are small, round bones that are embedded within tendons and help reduce friction, modify pressure, and assist in the smooth movement of muscles. Example: patella, bones in the hands and feet  Types of bones Visceral bones They are those bones form in soft tissues or organs, rather than in the skeleton. These get detached from the skeleton and come to lie in the visceral organs. It’s rare in humans. Example: bones in the septum of heart of deer etc.  Fluid connective tissue Blood is one the fluid connective tissue. It contains cells suspended in a liquid matrix (plasma). Contains: - Plasma - Blood Sugar - Blood Cholesterol - Blood Cells (RBC, WBC, Platelets) Lymph  lymph Lymph is a clear fluid that is similar to plasma but contains less protein. It flows through lymphatic vessels throughout the body and includes chemicals and cells whose composition varies according to location within the body. The functions of lymph are as follows: It is used to transport nutrients to the cells. It is used to provide intercellular communication between the cells It is used to remove the metabolic wastes from the cells.  plasma Plasma is a slightly alkaline, pale yellow fluid that constitutes about 60% of the blood. It contains electrolytes, hormones, nutrients, waste products and plasma proteins. It has 3 types of proteins: serum albumin, serum globulins and fibrinogen. These serves as the source of proteins to the tissue cells.  3 PLASMA PROTEINS 1. Serum albumin It maintains the osmotic pressure of the blood, which helps retain fluid within the blood vessels and prevent it from leaking into the surrounding tissues. It transports substances including hormones (such as thyroid hormones), fatty acids, and certain drugs. It acts as a carrier protein for these molecules. It helps maintain the pH balance of the blood by acting as a buffer.  3 PLASMA PROTEINS 2. Serum globulin It helps in immune response (immunoglobulins -- antibodies). They help recognize and neutralize foreign pathogens like bacteria and viruses. Some globulins, like lipoproteins, assist in transporting lipids and fat-soluble vitamins (such as vitamins A, D, E, and K) through the bloodstream.  3 PLASMA PROTEINS 3. Fibrinogen Fibrinogen is a key protein in the blood clotting process. When there is an injury, fibrinogen is converted into fibrin, which forms a mesh-like structure that helps stabilize and form a blood clot. This process prevents excessive bleeding and aids in wound healing.  Blood glucose Glucose is mainly absorbed in the liver and after absorption it reaches the blood. Excess of glucose is converted into glycogen by insulin in the liver and muscles which is kept as stored food. If the blood glucose level exceeds 180 mg per 100 ml, it starts appearing in urine and is called glucosuria in blood it is hyperglycemia. Glucose level after breakfast is 110-140 mg and if it is higher then it causes diabetes mellitus.  Blood cholesterol Cholesterol is needed in a very little amount in our body. Excess of cholesterol leads to the deposition of cholesterol in the veins and arteries which results in heart diseases. It reaches the blood either by intestinal absorption or synthesis by liver or both.  Blood cells 2 Main Types of Blood Cells: Red Blood Cell White Blood Cell  Red blood cell/ red blood corpuscles They are also called erythrocytes. These are formed in the maximum amount in the blood. It is red due to the present of the oxygen carrying pigments hemoglobin. Their main function is to transport oxygen and food to each part of the body and to remove some nitrogenous and other wastes from the body.  White blood cell/ white blood corpuscle These are also called leukocytes and they lack hemoglobin. It is mainly associated with the defense mechanism of the body. Rise in the level of WBC lead to leukemia (blood cancer).  Types of white blood cells Neutrophils: They are maximum in number. These help in phagocytosis. The pus contains dead neutrophils and living virus/bacteria. Eosinophils: They help in protecting from allergic reactions and parasitic infection. Basophil: These releases heparin and histamine which are anti-allergens. Lymphocytes: There are two types of lymphocytes. - B-lymphocytes produce antibodies against the antigens. - T-lymphocytes do not directly kill the foreign bodies but helps B- lymphocytes in providing immunity. They are also called helper T cells. Monocytes: These are the largest WBC. They also help in phagocytosis.  Muscular tissue Muscle tissues helps in the contraction and functioning of muscle responsible for locomotion and movement of organs. 3 Classifications: - Smooth Muscle - Skeletal Muscle - Cardiac Muscle 3 types of muscular tissues  Skeletal muscle cells These are attached to bones by tendons which generates body movements. These are made up of striated muscle fibres. The cells have striations, alternating light and dark bands that result from the ordered arrangement of actin and myosin within the cell.  Smooth muscle cells It is known as “non-striated muscle” Smooth muscle tissue is found in the walls of hollow organs, such as the gastrointestinal tract, blood vessels, and the urinary bladder. Smooth muscle cells are not striated and have tapered ends. Involuntary muscle cells. Contractions of these muscles propel fluid or materials through the organs (i.e. food through the GI tract, blood through blood vessels, urine pushed out of bladder).  Cardiac muscle These can be found in the heart only. These are also involuntary in action. It also shows cross-striation but much fainter than in striated muscles. It is responsible for the pumping of heart.  Nervous tissue Nervous tissue is specialized for communication and composes the brain, spinal cord, and peripheral nerves. The tissue consists of two major cell types: neurons and glial cells.  NEURONS Neurons communicate with each other via electrical and chemical signals. They have nucleated cell bodies and two types of elongated cellular processes: dendrites – which receive signals, and axons – which send signals. neuron  MYELIN SHEATH A protective, insulating layer that surrounds the axons of certain nerve cells (neurons) in both the central nervous system (CNS) and peripheral nervous system (PNS). It enhances the speed and efficiency of electrical signal transmission along the neuron.  Cell body (SOMA) The central part of a neuron that contains the nucleus and other essential organelles. It receives electrical signals from the dendrites and integrates these signals to be interpreted which leads to a response.  NODES OF RANVIER They are small gaps in the myelin sheath that cover the axons of neurons. It allows electrical impulses (action potentials) to travel much faster and more efficiently compared to unmyelinated fibers.  Glial cells It is also called neuroglia. Glial cells are the support cells of nervous tissue. There are several different types with various functions depending on the cell involved… Glial cells Neuron-Glial antigen 2