Anaphy 5 & 6

• Tissues are groups of similar cells and their intercellular substance that have a similar embryological origin and function together to perform a specialized activity
• Histology is the science that deals with the study of tissues
• There are 4 different types of tissues: epithelial tissues, connective tissues, muscle tissues, and nervous tissues
• Epithelial tissues cover body surfaces, line body cavities and ducts, and form glands
• Covering & lining epithelium forms the outer covering of external body surfaces and some internal organs
• Simple epithelium is specialized for absorption and filtration with minimal wear & tear, and is single-layered
• Stratified epithelium is many-layered and found in areas with a high degree of wear & tear
• Pseudo-stratified epithelium is single-layered but appears to have many layers, found in larger excretory ducts of many glands
• Transitional epithelium is found in the urinary bladder, part of ureters, and urethra, and allows the tissue to stretch without breakage
• Glandular epithelium's main function is secretion and can be classified into exocrine and endocrine glands
• Connective tissues bind structures together, form a framework and support for organs and the body, store fat, transport substances, protect against disease, and help repair tissue damage
• Mucous connective tissue is found primarily in the fetus and located in the umbilical cord
• Adult connective tissue composes connective tissue proper, cartilage, osseous (bone), and vascular (blood) tissue
• Muscle tissue consists of highly specialized cells that provide motion, maintenance of posture, and heat production
• Skeletal muscle tissue is attached to bones, voluntary, cylindrical, multinucleated, and striated
• Cardiac muscle tissue forms the wall of the heart, involuntary, uni-nucleated, and striated
• Smooth muscle tissue is located in the wall of hollow internal structures like blood vessels, stomach, intestine, and urinary bladder, and is involuntary and non-striated
• Nervous tissues contain neurons and neuroglia, with neurons being the structural and functional unit of the nervous system
• Neurons consist of cell body (soma), axons, and dendrites
• Neuroglias protect, nourish, and support neurons, and have the potential to replicate and produce cancerous growths
• Membranes are thin, pliable layers of epithelial and/or connective tissue that line body cavities, cover surfaces, and connect or separate regions, structures, and organs of the body
• There are 3 kinds of membranes: mucous membranes, serous membranes, and cutaneous membranes
• Serous Membrane:

  • Contains loose connective tissue covered by a layer of mesothelium
  • Pleura and pericardium are serous membranes that line the thoracic and heart cavities respectively
  • Epithelial layer of a serous membrane secretes lubricating fluid called serous fluid, allowing organs to glide easily
• Synovial Membrane:

  • Does not contain epithelium
  • Lines the cavities of freely movable joints
  • Secretes synovial fluid that lubricates articular cartilage at the ends of bones as they move at joints
• Integumentary System:

  • Skin is a remarkable organ, the first line of defense that keeps bacteria out and retains water and heat
  • Epidermis is a layer of avascular epithelial tissue that gets nutrients through diffusion from the dermis
  • Dermis is a tough layer of vascularized fibrous tissue, full of nerves and blood vessels
  • Hypodermis is a layer of adipose tissue that anchors the skin to structures below
• Skin Appendages:

  • Hair is a flexible strand made of dead, keratinized cells produced by hair follicles
  • Nails contain hard keratin and have parts like free edge, body, proximal root, nail bed, nail matrix, nail folds, and hyponychium
• Glands:

  • Sweat glands, also known as sudoriferous glands, are found almost everywhere on the skin
  • Two types of sweat glands: eccrine/merocrine sweat glands and apocrine sweat glands
  • Apocrine glands secrete fat and protein components along with the normal mixture, causing body odor
  • Types of apocrine glands include ceruminous glands (produce earwax), mammary glands (produce breast milk), and sebaceous glands (oil glands)
• Metabolism:

  • Metabolism is the chemical reactions inside the body to convert food into energy, build and repair tissues, and remove waste
  • Catabolism breaks down larger molecules into smaller ones, releasing energy
  • Anabolism builds larger, more complex molecules from smaller ones
  • Liver plays a central role in regulating metabolism
  • Insulin is involved in glucose uptake and storage in metabolism
• Simple – Squamous epithelium, contain single layer of flat, scale like resemble tiled floor. Thus, it lines the air sacs of lung, in kidneys, blood vessels and lymph vessels.
• Simple – cuboidal epithelium, Flat polygon that covers the surface of ovary, lines the anterior surface of lens of the eye, retina & tubules of kidney
• Simple – columnar epithelium, Similar to simple cuboidal. It is modified in several ways depending on location & function. It lines the gastro -intestinal tract gall bladder, excretory ducts of many glands. It functions in secretions, absorption, protection & lubrication
• According to the arrangement of layers covering and lining epithelium is grouped into: simple epithelium, stratified epithelium, and pseudo-stratified epithelium
• TYPES OF SIMPLE EPITHELIUM: Stratified squamous, Stratified cuboidal, Stratified columnar
• TYPES OF STRATIFIED EPITHELIUM: Stratified squamous, Stratified cuboidal, Stratified columnar
• Stratified Squamous epithelium: the outer cells are flat.
• Stratified Squamous epithelium is subdivided in to two based on presence of keratin: Non -Keratinized stratified squamous epithelium, Keratinized stratified squamous epithelium
• Non -Keratinized stratified squamous epithelium is found in wet surface that are subjected to considerable wear and tear. Example: - Mouth, tongue and vagina.
• Keratinized stratified squamous epithelium - the surface cell of this type forms a tough layer of material containing keratin. Example: skin.
• Keratin- is a waterproof protein, resists friction and bacterial invasion.
• Stratified cuboidal epithelium, rare type of epithelium. - It is found in sweat glands duct, conjunctiva of eye, and cavernous urethra of the male urogenital system, pharynx & epiglottis. - Its main function is secretion.