Week 3 - Tissues, Glands and Membranes PDF

TISSUES, GLANDS AND MEMBRANES  Why is it important to study the tissues? KNOWLEDGE OF TISSUE STRUCTURE AND FUNCTION IS IMPORTANT IN UNDERSTANDING HOW INDIVIDUAL CELLS ARE ORGANIZED TO FORM TISSUES AND HOW TISSUES ARE ORGANIZED TO FORM ORGANS, ORGAN SYSTEMS, AND THE COMPLE...

TISSUES, GLANDS AND MEMBRANES  Why is it important to study the tissues? KNOWLEDGE OF TISSUE STRUCTURE AND FUNCTION IS IMPORTANT IN UNDERSTANDING HOW INDIVIDUAL CELLS ARE ORGANIZED TO FORM TISSUES AND HOW TISSUES ARE ORGANIZED TO FORM ORGANS, ORGAN SYSTEMS, AND THE COMPLETE ORGANISM. TISSUES A TISSUE (TISH′ Ū ) IS A GROUP OF CELLS WITH SIMILAR STRUCTURE AND FUNCTION THAT HAVE SIMILAR EXTRACELLULAR SUBSTANCES LOCATED BETWEEN THEM. THE MICROSCOPIC STUDY OF TISSUE STRUCTURE IS CALLED HISTOLOGY (HIS-TOL′ Ō -JE; HISTO-, TISSUE + - OLOGY, STUDY)  TISSUES ⮚ The structure of each tissue type is related to its function (meaning, the shape and size of tissue have a reason and that is related to its function) ⮚ Disease may be caused by changes in tissues. Basic Types of Tissues  EPITHELIAL TISSUE Covers external and internal surfaces throughout the body. Consists almost entirely of cells with very little extracellular material between them. May consist of a single layer of epithelial cells or multiple layers of epithelial cells between the free surface and the basement membrane. Epithelial cells Three types of Epithelium (based on shapes): ⮚ Squamous – cells are flat, scale like. ⮚ Cuboidal – cells are cube shaped about as wide as they are tall, cube like. ⮚ Columnar – cells tend to be taller than they are wide Epithelial cells Classifications of Epithelia: ⮚ Simple epithelium – consists of single layer of cells, with each cell extending from the basement membrane to free surface ⮚ Stratified epithelium – consists of more than one layer of cells, but only the basal layer attaches the deepest layer to the basement membrane Epithelial cells Classifications of Epithelia: ⮚ Pseudostratified columnar epithelium is a special type of simple epithelium, that appears to be falsely stratified. It consists of one layer of cells, with all the cells attached to the basement membrane. Due to variations in the shape of the cells, the epithelia appears stratified. Simple Epithelium Simple Squamous Epithelium Structure: Function Location Single Layer of flat, Diffusion, filtration, ⮚ Lining of blood Often hexagonal some secretion vessels cells; the nuclei and some ⮚ Lymphatic appear as bumps protection against vessels when viewed in friction ⮚ Alveoli cross section ⮚ Kidney tubules because the cells ⮚ Lining of serous are so flat membranes (pleural, pericardial, peritoneal) Simple Epithelium Simple Cuboidal Epithelium Structure: Function Location Single layer of Secretion and ⮚ Kidney tubules cube shape cells, absorption ⮚ Glands some cells have ⮚ Bronchioles of microvilli or cilia lungs ⮚ Surface of the ovaries Simple Epithelium Simple Columnar Epithelium Structure: Function Location Single layer of tall ⮚ Movement of ⮚ Kidney tubules narrow cells some particles out of ⮚ Glands cells have microvilli the bronchioles ⮚ Bronchioles of or cilia of the lungs by lungs ciliated cells, ⮚ Uterine tubes ⮚ partially ⮚ Stomach responsible for ⮚ Intestines the movement of ⮚ Gall bladder oocytes through the uterine ⮚ Secretion Simple Epithelium Pseudostratified Columnar Epithelium Structure: Function Location Single layer of ⮚ Synthesize and ⮚ Lining of nasal cells; some cells secrete mucus cavity are tall and thin onto the free ⮚ Nasal sinuses and reach the free surface ⮚ Auditory tubes surface, The cells ⮚ Move mucus that ⮚ Pharynx are almost always contains foreign ⮚ Trachea ciliated and are particles over the ⮚ Bronchi of lungs associated with surface of the goblet cells that free surface secrete mucus onto free surface Simple Epithelium Stratified Squamous Epithelium Structure: Function Location ⮚ Several layers of ⮚ Protects against ⮚ Keratinized outer cells that are abrasion layer of the skin cuboidal in the ⮚ Forms a barrier ⮚ Non – basal layer against infection Keratinized ⮚ Progressively (Mouth, Throat, flattened toward Larynx, the surface Esophagus, Anus, Vagina, Inferior urethra) Simple Epithelium Transitional Epithelium Structure: Function Location ⮚ Stratified cells ⮚ Accommodates ⮚ Lining of urinary that appear fluctuations in the bladder, ureter cuboidal when volume fluid in an and superior the organ or tube organ or a tube urethra is not stretched ⮚ Protects against and squamous the caustic when the organ effects of urine or tube is stretched by fluid FUNCTIONAL CHARACTERISTICS Free surfaces ⮚ Smooth – reduces friction as material moves across it (lined with microvilli or cilia) ⮚ Endothelium – the lining of the blood vessels is a specialized type of simple squamous epithelium (smooth) Cell Connection ⮚ Cells have structures that hold one cell to another or to the basement membrane. ⮚ These structures do 3 things: 1. Mechanically bind the cells together. 2. Helps form a permeability barrier. 3. Provides a mechanism for intercellular communication. Cell Connection ⮚ Desmosomes (a band) – are mechanical links that bind cells together ⮚ Hemidesmosomes (modified desmosomes) – also anchor cells to the basement membrane ⮚ Tight junction – bind adjacent cells together Cell connection ⮚ Gap junctions – small channels that allow small molecules and ions to pass from one epithelial cell to an adjacent one Glands Secretory Organs ⮚ Composed of epithelium with a supporting network of connective tissue How do glands develop? ⮚ By infolding or outfolding of epithelium in the embryo Glands ⮚ If the gland maintains an open contact with the epithelium from which it develop, a duct is present. ⮚ Exocrine glands – glands with duct ⮚ Endocrine glands – glands without duct ⮚ Hormones – cellular products of endocrine glands Nervous tissues ⮚ Forms the brain, spinal cord and nerves ⮚ Responsible for coordinating and controlling many body activities ⮚ Conscious control of skeletal muscles and unconscious regulation of cardiac muscle are all accomplished by nervous tissue Nervous tissue Nervous Tissue Structure: Function Location ⮚ A neuron ⮚ Neurons transmit ⮚ In the brain consists of information in the ⮚ Spinal cord dendrites form of action ⮚ ganglia ⮚ A cell body and a potentials long axon, glia or ⮚ Store information support cells ⮚ Integrate and surround neuron evaluate data ⮚ Protect and form specialized sheaths around axons Nervous Tissue  Muscle Tissues ⮚ is to contract or shorten, making movements possible ⮚ Muscle contraction results from contractile proteins located within the muscle cells  Skeletal Muscle Muscle tissue Structure: Function Location ⮚ Skeletal muscle ⮚ Movement of the ⮚ Attach to bone or cells or fibers body under other connective appear striated voluntary control tissue (banded) ⮚ Cells are large, long and cylindrical with many nuclei Muscle tissue Cardiac Muscle Structure: Function Location ⮚ Cardiac muscle ⮚ Pumps the blood ⮚ In the heart cells are ⮚ Under cylindrical and involuntary striated and have (Unconscious) single nucleus control ⮚ Branched and connected to one another by intercalated disks which contain gap junctions Muscle tissue Smooth Muscle Structure: Function Location ⮚ Smooth muscle ⮚ Regulate the size ⮚ In hollow organs cells are tapered of the organs such as the at each end, are ⮚ Forces fluid stomach and the not striated through tubes intestines ⮚ Have single ⮚ Controls the ⮚ Skin nucleus amount of light ⮚ eyes entering the eye ⮚ Produces goosebumps in the skin  Connective Tissues ⮚ Is a diverse primary tissue type that make up every organ in the body. Connective tissue differs from the other 3 tissue types in that it consist of cells separated from each other by abundant extracellular matrix Example of an Areolar Connective Tissue Connective tissue Areolar Connective Tissue Structure: Function Location ⮚ Fine network of ⮚ Loose packing ⮚ Widely fibers with ⮚ Support distributed spaces between ⮚ Nourishment for throughout the the structures body with which it is ⮚ Substances in associated which epithelial basement membrane rest ⮚ Muscles ⮚ Nerves ⮚ Attaches skin to underlying tissues Connective tissue Adipose Tissue Structure: Function Location ⮚ Little extracellular ⮚ Packing material ⮚ Widely matrix ⮚ Thermal insulator distributed surrounding cells ⮚ Energy storage throughout the ⮚ Fat cells are so ⮚ Protection of body full of lipids that organs against ⮚ Substances in the cytoplasm is injury from being which epithelial pushed to the bumped or jarred basement periphery of the membrane rest cell ⮚ Muscles ⮚ Nerves ⮚ Attaches skin to underlying tissues Connective tissue Reticular Tissue Structure: Function Location ⮚ Fine network of ⮚ Provides a ⮚ Within lymph reticular fibers superstructure nodes irregularly for lymphatic and ⮚ Spleen arranged hemopoietic ⮚ Bone marrow tissues  Dense Regular Collagenous Connective Connective tissue Tissues Structure: Function Location ⮚ Matrix composed ⮚ Withstand great ⮚ Tendons (attach of collagen fibers pulling forces muscle to bones) running in exerted in the ⮚ Ligaments somewhat the direction of fiber (Attach bones to same direction in orientation due to bones) tendons and great tensile ligaments strength and ⮚ Run in several stretch directions in the resistance dermis of the skin and in organs capsules Connective tissue Dense Regular Elastic Connective Tissues Structure: Function Location ⮚ Matrix composed ⮚ Capable of ⮚ Elastic ligaments of collagen fibers stretching and between the running in recoiling like a vertebrae and somewhat the rubber band with along the dorsal same direction in strength in the aspect of the elastic ligaments direction of fiber neck ⮚ Elastic fiber run orientation ⮚ Vocal cords in connective ⮚ Blood vessel tissue of blood walls vessels wall Connective tissue Hyaline Cartilage Structure: Function Location ⮚ Collagen fibers ⮚ Allows growth of ⮚ Growing long are small and long bones bones evenly dispersed ⮚ Provides rigidity ⮚ Cartilage rings of in the matrix with some the respiratory ⮚ Chondrocytes flexibility in system are found in trachea, bronchi, ⮚ Costal cartilage spaces ribs and nose of ribs ⮚ Nasal cartilage Connective tissue Fibrocartilage Structure: Function Location ⮚ Collagen fibers ⮚ Somewhat ⮚ Inverted disks similar to those in flexible and pubic symphysis hyaline cartilage capable of and articular ⮚ Fibers are more withstanding disks (Knee and numerous than in considerable temporomandibul other cartilages pressure ar (Jaw) joints) and are arranged connects in thick bundles structures subjected to great pressure  Elastic Cartilage Connective tissue Structure: Function Location ⮚ Similar to hyaline ⮚ Provides rigidity ⮚ External ears cartilage, but with even more ⮚ Epiglottis matrix also flexible than ⮚ Auditory tubes contains elastic hyaline cartilage fibers because elastic fibers return to their original shape after being stretched Connective tissue Supporting Connective Tissue Structure: Function Location ⮚ Hard ⮚ Provides great ⮚ All bones of the ⮚ Bony matrix strength and body ⮚ Many osteocytes support and protects internal organs such as brain ⮚ Bone also provides attachment sites for muscles and ligaments Connective tissue Fluid Connective Tissue: Blood Structure: Function Location ⮚ Formed elements ⮚ Transport ⮚ Within the blood ⮚ Fluid matrix oxygen, carbon vessels dioxide, ⮚ White blood cells hormones, frequently leave nutrients, waste the blood vessels products and and enter other substances extracellular ⮚ Protects body spaces from infection Tissue Membranes ⮚ Is a thin sheet or later of tissue that covers structure or lines a cavity (consist of epithelium) ⮚ There are 4 membranes in the body 1 external and 3 internal ⮚ External tissue membrane is the skin Tissue Membranes Mucous Membrane ⮚ Line cavities that open to the outside of the body such as: ▪ Digestive ▪ Respiratory ▪ Reproductive tracts Tissue Membranes Serous Membrane ⮚ Line cavities that do not open to exterior of the body such as: Pleural Pericardial Peritoneal Tissue Membranes Synovial Membrane ⮚ Line cavities of freely movable joints ⮚ Synovial fluid – makes joints very slippery, thereby reducing friction and allowing smooth movement within the joint Inflammation Occurs when tissues are damaged. Example: ⮚ When viruses infect epithelial cells of the upper respiratory tract ⮚ Inflammation are produced ⮚ Inflammation can also result from the immediate and painful events that follow trauma ⮚ Inflammation mobilize the body defenses and isolates and destroys microorganisms  Inflammation Major Symptoms of Inflammation: ✔ Heat ✔ Redness ✔ Swelling ✔ Pain ✔ Disturbance of function Inflammation ⮚ Chemical mediators – released or activated in the injured tissues ⮚ This includes histamine and prostaglandin ⮚ Chemical mediators also increase permeability of blood vessels ⮚ Edema – Swelling, This mechanism helps prevent the spread of infectious agents Inflammation ⮚ Chronic inflammation – results when the agent responsible for an injury is not removed or something else interferes with the healing process Tissue Repair ⮚ Is the substitution of viable cells for dead cells ⮚ Repair can occur through regeneration or by fibrosis ⮚ Fibrosis – replacement a new type of tissue develops that eventually causes scar production THANK YOU! Prepared by BIO101 Instructors