BASIC TISSUES OF HUMAN BODY (1).pdf

BASIC TISSUES OF HUMAN BODY PRESENTED BY: DR. UMBREEN BANO LECTURER DEPARTMENT OF ANATOMY  OBJECTIVES At the end of class students should be able to: 1. Describe the structure and functions of epithelial, connective and muscular and nervous tissue 2. i...

BASIC TISSUES OF HUMAN BODY PRESENTED BY: DR. UMBREEN BANO LECTURER DEPARTMENT OF ANATOMY  OBJECTIVES At the end of class students should be able to: 1. Describe the structure and functions of epithelial, connective and muscular and nervous tissue 2. identify the different types of epithelial, connective and muscular and nervous tissue  TISSUES Definition: A group of cells with a similar properties i-e: shape, function called as tissue Basic tissues classified into four groups: 1. Epithelial tissue 2. Muscular tissue 3. Connective tissue 4. Nervous tissue  Epithelial tissue Epithelium covering the body surfaces and lining cavities, hollow organs and tubes. Also found in glands. The cells are very closely packed and the intercellular substance, called the matrix, is minimal. The cells usually lie on a basement membrane Epithelium is avascular The structure of epithelium is closely related to its functions, which include: protection of underlying structures from, for example, dehydration, chemical and mechanical damage secretion absorption  Classification of epithelim Number of layers of cells : Simple epithelium: consists of a single layer of identical cells Stratified epithelium: several layers of cells. According to the shape of the cells: Squamous (pavement) epithelium This is composed of a single layer of flattened cells The cells fit closely together like flat stones, forming a thin and very smooth membrane across which diffusion easily occurs Heart – where it is known as endocardium alveoli of the lungs, lining the collecting ducts of nephrons in the kidneys  Classification of epithelim Cuboidal epithelium: Consists of cube-shaped cells fitting closely together lying on a basement membrane kidney tubules and is found in some glands. Function: Cuboidal epithelium is actively involved in secretion, absorption and excretion. Columnar epithelium: This is formed by a single layer of cells, rectangular in shape, on a basement membrane It lines many organs and often has adaptations that make it well suited to a specific function. The lining of the stomach is formed from simple columnar epithelium without surface structures. The surface of the columnar epithelium lining the small intestine is covered with microvilli, with cilia lining the trachea, fallopian tube  STRATIFIED EPITHELIUM Depending on the shape of upper most cell layer it is further subdivided into: Stratified squamous: THIS EPITHELIUM IS OF TWO TYPES Stratified cuboidal Stratified columnar  Types of stratified squamous epithelium Keratinised stratified squamous epithelium This is found on dry surfaces subjected to wear and tear, i.e. skin, hair and nails. The surface layer consists of dead epithelial cells that have lost their nuclei and contain the protein keratin. This forms a tough, relatively waterproof protective layer that prevents drying of the live cells underneath. The surface layer of skin is rubbed off and is replaced from below. Non-keratinised stratified squamous epithelium This protects moist surfaces subjected to wear and tear, and prevents them from drying out, e.g. the conjunctiva of the eyes, the lining of the mouth, the pharynx, the oesophagus and the vagina  FUNCTIONS OF EPITHELIUM 1.Protection: all epithelia protect underlying CT – however this ability is most marked in the stratified squamous epithelium 2. Secretion 3.Absorption 4.Excretion 5.Transport  Transitional epithelium (Urothelium) it has some features which are intermediate between stratified cuboidal and stratified squamous epithelia. It is exclusively found in the urinary tract to withstand the toxicity of urine and to accommodate great degree of stretch. This epithelium varies in thickness from a minimum of two layers of cells when the bladder is distended, to four or five layers when the bladder is empty. EXAMPLES: Renal calyces renal pelvis, ureters, urinary bladder & part of urethra (Prostatic)  MUSCULAR TISSUE (MUSCLE) DEFINITION Muscle is a contractile tissue which brings about movements. TYPES OF MUSCLES 1. Skeletal Muscles (Striated or Voluntary) They exhibit cross-striations under microscope. They are supplied by spinal nerves, and, therefore, are under voluntary control. 2. Smooth Muscles (Non-striated or involuntary) They do not exhibit cross-striations under microscope, being plain and smooth in form. They are supplied by autonomic nerves, and therefore, are not under voluntary control. 3. Cardiac Muscle It forms myocardium of the heart. It is intermediate in structure, being striated and at the same time involuntary. Each muscle fibre anastomoses with the neighbouring fibres at intercalated discs.  SKELETAL MUSCLE PARTS OF A MUSCLE Two ends ORIGIN It is one end of the muscle which remains fixed during its contraction. INSERTION It is the other end which moves during its contraction. Two parts FLESHY PART It is contractile, and is called the ‘belly’. FIBROUS PART It is noncontractile and inelastic. (tendon or aponeurosis)  PARTS OF SKELETAL MUSCLE Tendon Apponeurosis Raphe  STRUCTURE OF STRIATED MUSCLE Each muscle is composed of numerous muscle fibres. Embedded in the sarcoplasm there are: Several hundred of nuclei arranged at the periphery beneath the sarcolemma. A number of evenly distributed longitudinal threads called myofibrils. Each myofibril is composed of longitudinal protein filaments, called myofilaments, which are the actual contractile elements of the striated muscle. Myofilaments are of two types, the thin ACTIN filaments, and the thick MYOSIN filaments. During muscular contraction, the actin filaments slide between the myosin filaments towards the center of the sarcomere, with shortening of the contractile unit.  SUPPORTING TISSUE Endomysium It surrounds each muscle fibre separately. Perimysium It surrounds bundles (fasciuli) of muscle fibres of various sizes. Epimysium It surrounds the entire muscle.  CLASSIFICATION OF SKLETAL MUSCLE On the basis of movement: Flexors Extensors Adductors Abductors Rotators On the basis of shape Fan shape Triangular shape Fusiform UNIPENNATE BIPENNATE MULTIPENNATE.  SKELETAL MUSCLE BLOOD SUPPLY OF SKELETAL MUSCLE Blood supply is derived from muscular branches from the neighbouring arteries. The arteries, veins and motor nerve pierce the muscle at a fairly constant point called neurovascular hilum. NERVE SUPPLY OF SKELETAL MUSCLE Motor point It is the site where the motor nerve enters the muscle. It may be one or more than one. Motor Unit (myone) It is defined as a single alpha motor neurons together with the muscle fibres supplied by it. The size of motor unit depends upon the precision of muscle control.  SMOOTH MUSCLE Smooth muscle consists of long, spindle- shaped cells closely arranged in bundles or sheets. In the tubes of the body it provides the motive power for propelling the contents through the lumen. In the digestive system it also causes the ingested food to be thoroughly mixed with the digestive juices. A wave of contraction of the circularly arranged fibers passes along the tube, milking the contents onward. By their contraction, the longitudinal fibers pull the wall of the tube proximally over the contents. This method of propulsion is referred to as peristalsis. In storage organs such as the urinary bladder and the uterus, the fibers are irregularly arranged and interlaced with one another. Their contraction is slow and sustained and brings about expulsion of the contents of the organs.  CARDIAC MUSCLE Cardiac muscle consists of striated muscle fibers that branch and unite with each other. It forms the myocardium of the heart. Its fibers tend to be arranged in whorls and spirals, and they have the property of spontaneous and rhythmic contraction. Specialized cardiac muscle fibers form the conducting system of the heart. Cardiac muscle is supplied by autonomic nerve fibers that terminate in the nodes of the conducting system and in the myocardium.  CONNECTIVE TISSUE It is also called supporting tissue These tissues connect and support other tissue of the body Connective tissue usually contains blood vessels and mediate the exchange of nutrients , metabolites and waste products b/w tissues and circulatory system It also plays important role in defence of the body  STRUCTURE OF THE CONNECTIVE TISSUE Connective tissue consists of cells and large amount of extracellular matrix. – The matrix includes ground substance and thread like formed elements the fibers collagen fibers elastic fibers reticular fibers Different types of CT differ from each other in cell variety chemical composition of the ground substance and number and kind of fibers Connective tissue cells: Fibroblasts (fibrocytes) Marcophages (histiocytes) Plasma cells Mast cells Adipocytes (fat cells) Wandering blood cells - neutrophils, eosinophils, basophils, and lymphocytes.  The following varieties of cells are present in connective tissue: Fibroblasts (fibrocytes) Marcophages (histiocytes) Plasma cells Mast cells Adipocytes (fat cells) Wandering blood cells - neutrophils, eosinophils, basophils, and lymphocytes.  CLASSIFICATION OF CONNECTIVE TISSUE  FUNCTIONS: Food reserve / an important energy store (mainly white cell) Mechanical function (act as shock absorbing pads/ cushion against mechanical shock ) Regulation of body temperature –Production of heat in first few months of postnatal life, to protect the new born against cold. (mainly brown fat) –By acting as a Thermal insulator under skin  NERVOUS TISSUE Permanent tissue of the body Made up of neurons and neuroglial cells Controls all functions of the body  STRUCTURE OF NEURON All neurons have a cell body (or SOMA) which contains cellular organelles, including a nucleus, a nucleolus, lots of rough endoplasmic reticulum, and so on. Most nerve cells have processes called DENDRITES, in that they receive input to the cell. Most neurons also have a single long process called an AXON, which is capable of transmitting NERVE IMPULSE from the cell body to some distant target.  TYPES OF NEURON ACCORDING TO THE Unipolar STRUCTURE Has an axon but no dendrites. Mostly primary sensory fibres. Bipolar Has an axon and a dendrite. Part of specialised sensory organs. Multipolar Has one axon and numerous dendrites. Motor and interneurons.  Neuron Types Direction of the Action Potential Sensory (Afferent) Neurons Conduct signals to the CNS. Motor (Efferent) Neurons Conduct signals from the CNS to the muscles. Interneurons (Association Neurons) Conduct signals from one neuron to another.  NEUROGLIAL CELLS They have a number of supporting roles throughout the nervous system and there are 5 different types of neuroglia cells which carry out these functions. Location Function Neuroglia  Star shaped cells that help keep the neurons in place as well as regulating the Astrocytes CNS composition of the surrounding extracellular fluid. Ependymal cells CNS  Secrete and move the cerebral spinal fluid. Microglia CNS  They engulf unwanted tissue in the CNS, e.g. microorganisms and damaged tissue. Oligodendrocytes CNS  Each cell forms myelin sheaths around multiple axons in the CNS. Schwann Cells PNS  Each cell forms a myelin sheath around a single axon in the PNS.  MAJOR SUBDIVISIONS OF THE NERVOUS SYSTEM the CENTRAL NERVOUS SYSTEM (CNS) and the PERIPHERAL NERVOUS SYSTEM (PNS). The CNS consists of the BRAIN and SPINAL CORD. The CRANIAL CAVITY houses the brain, and the VERTEBRAL CANAL, houses the spinal cord. The PNS consists of the 12 pairs of CRANIAL NERVES and 31 pairs o SPINAL NERVES