TISSUES (1).pptx

TISSUES A tissue is a group of cells that have similar structure and that function together as a unit. They have intercellular matrix that fills the spaces between the cells.  TISSUES The intercellular matrix may contain special substances such as salts a...

TISSUES A tissue is a group of cells that have similar structure and that function together as a unit. They have intercellular matrix that fills the spaces between the cells.  TISSUES The intercellular matrix may contain special substances such as salts and fibres that are unique to a specific tissue and this gives the tissue distinctive characteristics.  TYPES OF TISSUES Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue  EPITHERIAL TISSUES Epithelial tissues are found throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs and glands.  FUNCTION OF EPITHERIAL TISSUES Their functions include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.  EPITHERIAL CELLS The cells in epithelial tissues are tightly packed together with very little intercellular matrix. They have an underlining basement membrane (a connective tissue).  EPITHERIAL CELLS The basement membrane is a mixture of carbohydrates and proteins secreted by the epithelial and connective tissue cells.  Epithelial Cells Epithelial cells may be squamous, cuboidal, or columnar in shape and may be arranged in single or multiple layers. TYPES OF EPITHERIAL TISSUES  Simple Squamous Epithelium Thin, flat plates (pavement appearance). They fit closely together in tissues, which provides a smooth, low-friction surface over which fluids can easily move.  Simple Squamous Epithelium The shape of the nucleus are horizontal, flat elliptical (oval shaped like an egg). Classically, squamous epithelia line surfaces such as the alveolar epithelium in the lungs.  Simple Squamous Epithelium Specialised squamous epithelia also form the lining of cavities such as: the blood vessels (endothelium), lymph vessels, pericardium (mesothelium) and the major cavities found within the body.  2. Simple Cuboidal Epithelium The cells are roughly cuboidal in shape, appearing square cell has a spherical nucleus in the centre. They also constitute the germinal epithelium that covers the female ovary.  Simple cuboidal Epithelium Tissues They are found in secretive or absorptive tissue such as exocrine gland of the pancreas, kidney tubules and ducts of the glands.  Functions of simple cuboidal epithelium Secretion, Absorption Excretion.  3. Simple Columnar Epithelium Cells are elongated and (rectangular shaped ). Their nuclei are elongated and are usually located near the base of the cells. They forms the lining of the stomach and intestines.  FUNCTIONS OF THE SIMPLE COLUMNAR EPITHELIUM For sensory reception such as those in the nose, ears and the taste buds of the tongue.  FUNCTIONS OF THE SIMPLE COLUMNAR EPITHELIUM They secrete mucus, which acts as a lubricant. For example Goblet cells (unicellular glands) are found between the columnar epithelial cells of the duodenum.  PSEDOSTRATIFIED OR SIMPLE CILIATED EPITHERIAL TISSUE The nuclei appear at different heights, giving the misleading (hence "pseudo") May have fine hair-like extensions on their apical (luminal) membrane called cilia.   PSEUDOSTRATIFIED OR SIMPLE CILIATED EPITHERIAL TISSUE The wafting effect produced causes mucus secreted locally by the goblet cells (to lubricate and to trap pathogens and particles).  Pseudostratified or simple ciliated epithelial tissue Ciliated epithelium is found in the airways (nose, bronchi) Fallopian tubes.   Stratified Squamous Epithelium It is a multi-layered tissue, thickest and found in body lining that withstand mechanical or chemical abrasion for example the Vagina. They does not contain junction complexes, and have cells bound together only by desmosomes.  Specializations: Stratified epithelia columnar, cuboidal or squamous have a specialization of being: Keratinized. The cells contain squamous cells known as keratinocytes  Keratinized They contains a tough, resistant protein called keratin. This specialization makes the epithelium waterproof. They are found on the mammalian skin.   Transitional Epithelium These are found in tissues that can stretch. For example the bladder, ureters and urethra.  2. CONNECTIVE TISSUE These tissue binds structures together to form a framework and support for organs. They contain numerous intercellular matrix with relatively few cells.  Function of connective tissues They stores fat (Adipose tissues) transports substances (blood), protects against disease, and helps to repair tissue damage.  Connective tissue They contain cells such as Fibroblasts (excrete extracellular matrix protein) Macrophages (WBCs involved in detection, phagocytosis and destruction of pathogens Mast cells. Cells that produces histamines, prostaglandins and brandykines chemical mediators.  Types of connective tissue Loose connective tissue Adipose tissue Dense fibrous connective tissue  Types of connective tissue Elastic connective tissue Cartilage Osseous tissue (bone) Blood Types of connective tissues Types of connective tissues  3. MUSCLE TISSUE They are composed of cells that have the ability to shorten or contract in order to produce movement of the body parts.  Muscle Tissue The tissue is highly cellular and is well supplied with blood vessels.  Muscle Tissue The cells are long and slender and are sometimes called muscle fibres. They are usually arranged in bundles or layers that are surrounded by connective tissue. They contain actin and myosin are contractile proteins found in muscle tissue. Myosin and Actin  Categories of muscle tissues Muscle tissues are categorized in the following: Skeletal muscle tissue Smooth muscle tissue Cardiac muscle tissue   Skeletal muscle Skeletal muscle fibres are cylindrical shape Skeletal muscle are multinucleated Skeletal muscles are striated. They work under voluntary control.   Cardiac muscles Cardiac muscle has branching fibres They have one nucleus per cell. They have striations and intercalated disks. Its contraction is under involuntary control.   Smooth muscles Smooth muscle cells are spindle shaped They have a single, centrally located nucleus The muscles lack striations. They work under involuntary muscles control   Nervous Tissue It is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities.  Nervous Tissue It stimulates muscle contraction It creates consciousness of an individual It plays a major role in emotions, memory, and reasoning.  Nervous Tissues In order to achieve all its functions, cells in nervous tissue communicate with each other by way of electrical nerve impulses. Neuron  Function of Neurons Neurons generate and conduct impulses are called neurons or nerve cells.  Glial cells or neuroglia cells These cells do not transmit impulses, but support the activities of the neurons. They bind neurons together and insulate the neurons.  Glial cells or neuroglia cells They act as phagocytic and protect against bacterial invasion, Others provide nutrients by binding blood vessels to the neurons.