Topic 3 - Body Language (Epithelia + Skin) 9f2cc7a07a8841af9da6b7b04a4b4d5e.pdf

👴🏾 Topic 3 - Body Language (Epithelia + Skin) Lecture 1 - Epithelia What are epithelia a sheet of cells that covers a body surface or lines a body cavity....

👴🏾 Topic 3 - Body Language (Epithelia + Skin) Lecture 1 - Epithelia What are epithelia a sheet of cells that covers a body surface or lines a body cavity. Nearly all substances received or given off by the body must pass through an epithelium layer Types of epithelia Topic 3 - Body Language (Epithelia + Skin) 1  Define Keratinised forms the outer layer of the skin protects underlying layers Topic 3 - Body Language (Epithelia + Skin) 2  What are “Pseudostratified epithelium” Topic 3 - Body Language (Epithelia + Skin) 3  Define “Transitional Epithelium” allows tissue to expand and contract. and change shape in response to fluid pressure For example, the transitional epithelium lines the inner walls of the urinary bladder, and this tissue allows the bladder to expand when the bladder fills with urine. Liver histology hexagonal lobules - each contains a portal triad (artery, vein & duct) centre - central vein (CV) stroma = supportive tissue Parenchyma - functional tissue hepatocytes (epithelia only found in the liver - responsible for a variety of cellular functions including carbohydrate, lipid and protein metabolism, detoxification) Topic 3 - Body Language (Epithelia + Skin) 4  What is the The basement membrane Sheets of matrix at interface of functional tissue (parenchyma) and support tissue (stroma). Cell Junctions - what is the purpose and state the different types of junctions communication + chemical support + stops epithelia from falling apart Occluding junctions - seal cells together in an epithelium that prevents even small molecules from leaking from one side of the sheet to the other. Anchoring junctions - form a tight seal between neighbouring cells and basement membrane for mechanical support Communicating junctions - allows communication + secretion between cells Topic 3 - Body Language (Epithelia + Skin) 5  TAD GH Tight Junction seals neighbouring cells in an epithelia sheet prevent leakage of molecules between them Adherens junction joins actin bundles in a cell to another bundle in a neighbouring cell Desmosome junctions Topic 3 - Body Language (Epithelia + Skin) 6  joins intermediate filaments in one epithelia cell to those neighbrouing filaments on another cell Gap junctions allows passage of small water-soluble ions and molecules hemidesmosome anchors intermediate filaments in a cell to the basement membrane/basal lamina what are the 3 types of exocrine glands secrets product through a duct or epithelial surface (sweat glands) Merocrine - secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct /ducts and then onto a bodily surface or into the lumen Apocrine - release some part of the cell along with their secretions in the form of vesicles Holocrine - characterized by disintegration/shedding of the entire cell in releasing its product Topic 3 - Body Language (Epithelia + Skin) 7  Endocrine release product into blood to act on distant tissues (pituitary, thyroid glands) Endocrine glands are distributed in ‘glands’ Endocrine glands are ductless, secreting their products directlyinto the bloodstream Endocrine function is regulated through neural connections in the brain via the hypothalamus and pituitary gland. Topic 3 - Body Language (Epithelia + Skin) 8  What is Adenocarcinoma cancer of glandular epithelium invasion of surrounding stromal tissues (supportive tissue) How does the pancreas have both a Exocrine + Endocrine Function? IoL - produces insulin Topic 3 - Body Language (Epithelia + Skin) 9  Lecture 2 - Skin what is the skin The skin is the largest organ of the body It acts as a physical barrier, protecting against infection, physical damage and chemical damage. touch, pressure, pain and temperature regulation What are the 3 main layers of the skin Epidermis derived from ectoderm keratainized stratified squamous epithelium contains keratinocytes → protective shields contains Langerhans cells Dermis Topic 3 - Body Language (Epithelia + Skin) 10  dense connective tissue derived from mesoderm contains fibroblasts → collagen, blood, mast cells, receptors & nerves flexibility and strength to skin to protect against external forces. sweat glands Hypodermis (subcutaneous tissue) main blood supply for the rest of the skin insulation 4 layers of epidermis (HGPB) 1. Horny layer (stratum corneum): Keratinocytes lose organelles and produce keratin. 2. Granular layer (stratum granulosum): Keratinocytes secrete waterproofing molecules for a protective barrier and moisture retention. 3. Prickle cell layer (stratum spinosum): Keratinocytes are tightly joined by desmosomes, providing structural support. 4. Basal layer (stratum basale/germinativum): Responsible for keratinocyte mitosis, the process of cell division. Topic 3 - Body Language (Epithelia + Skin) 11  2 types of sweat glands (dermis) Apocrine gland: Large sweat gland leading to body odour. (localised (axilla/groin)) Eccrine gland: secretes odourless, clear substance primarily composed of water and sodium chloride, vital for thermoregulation (throughout the body) Keratinocytes Keratinocytes: Produce keratin, a fibrous protein for skin strength, and found in hair and nails. Undergo mitosis in the basal layer. Move up through the prickle cell layer, losing the ability to divide and their nuclei, forming the horny layer. The horny layer provides a hydrophobic skin barrier due to keratin. Topic 3 - Body Language (Epithelia + Skin) 12  Melanocytes Located in the basal layer of the epidermis. Synthesize melanin, a pigment that darkens skin and offers UV protection. Darker-skinned individuals have melanocytes that produce more melanin, not more melanocytes. Langerhans Cells (epidermis) Antigen presenting cells. Circulate between the epidermis and local lymph nodes. Mediate immune responses. Merkel Cells Connected to keratinocytes and sensory nerves receive the sensation of touch Cell junctions in epidermis Epidermis structure: Avascular and multilayered with a basement membrane at the bottom. Cell junctions in epidermis: Tight junctions, desmosomes, gap junctions, and hemidesmosomes. Basal cells: Located just above the basement membrane. As basal cells move upwards, they divide and differentiate into keratin, forming the layers of the epidermis Topic 3 - Body Language (Epithelia + Skin) 13  Skin Histology Picture Skin Appendages Hair: Used for thermal regulation and display. Arrector pili: Muscle that erects hair, trapping air for heat retention. Sebaceous glands: Associated with hair follicles, secrete sebum for waterproofing. Sweat glands: Eccrine and apocrine Nails: Provide physical protection, composed of hard layers of keratin. Burns Topic 3 - Body Language (Epithelia + Skin) 14  First and second degree burns are also known as partial thickness because not all of the skin layers are destroyed. (Sunburn = 1st) Third degree burns are full thickness, affecting all layers and some underlying tissues. Tutorial Session What is the vertebrae 33 individual bones that interlock with each other to form the spinal column 4 parts of the vertebrae What is the sternal angle and its importance The sternum is a long, flat bone that protects the underlying muscles, organs, and important arteries within the chest. The movement at the sternal angle allows the body of the sternum to move anteriorly and superiorly. Topic 3 - Body Language (Epithelia + Skin) 15  Define ‘Fundus’ part of a hollow organ (such as the uterus or the gall bladder) that is furthest from the opening. Define Foramen opening hole in the bone, opening that allows the passage of structures from one region to another Define Fossa A shallow depression in the bone surface Topic 3 - Body Language (Epithelia + Skin) 16  Define Apex Pointed end of a conical structure (bottom of the heart). Define Prominence projection/elevation Define Adventitia outer layer of the wall of blood vessel Define Aponeurosis thin sheath of connective tissue that helps connect your muscles to your bones Define Septum separation between 2 sections Define Cortex outer region layer of an interal organ Define Lamina plate/layer Define Bifurcate point or area at which something divides into two branches or parts Define Sulcus a groove or furrow, especially one on the surface of the brain. Topic 3 - Body Language (Epithelia + Skin) 17 Topic 3 - Body Language (Epithelia + Skin) 18