Exam 2 (4) PDF - Keratinization and Skin Barrier Biology

LO4: Describe the processes of growth and keratinization (cornification) of the epidermis.  The process in which keratinocytes undergo cytodifferentiation as they transition from their initial stage in the stratum basale to become fully differentiated...

LO4: Describe the processes of growth and keratinization (cornification) of the epidermis.  The process in which keratinocytes undergo cytodifferentiation as they transition from their initial stage in the stratum basale to become fully differentiated, hardened cells filled with keratin protein. Desquamation- corneocytes shed into the environment (squames or horny cells) Consists of 20-30 layers of dead cells full of keratin Beneath the plasma membrane: cornified envelope (cross- cornified layer linked proteins+lipids) 3-5 Layers of flattened cells Presence of keratohyalin granules (with keratin filament- granular layer associated proteins) Lipids are stored in lamellar bodies Organelle & nucleus destruction (far from dermal capillaries) spinous layer Keratinocytes detach from the basal mb and start to undergo stoppingvisionen junctg adhesion differentiation formingeatin Keratin expression--Proliferation arrest--Desmosome formation basal layer undifferentiated, mitotic stem cells that are attached to the basement membrane. Continuously provide the stratified 1 single row of Cuboidal cells epithelium with new cells. Shetty, S., & Gokul S (2012). Keratinization and its disorders. Oman medical journal, 27(5), 348–357. https://doi.org/10.5001/omj.2012.90 Epidermis Cross Section Anatomy Skin 3D Model By zames1992 https://llllline.com/epidermis-cross-section-anatomy-skin https://doi.org/10.1038/sj.cdd.4401722  LO5: Explain how extracellular lipids within the stratum corneum contributes to the skin barrier “Brick & mortar” pattern They form the cutaneous permeability barrier They block the movement of water and electrolytes cell-cell junctions the primary fills the spaces between structural units, corneocytes offering strength Lipids are transferred to the extracellular spaces of the stratum corneum by lamellar bodies secreted as cells move from the stratum granulosum to the stratum corneum. (also called lamellar granules) Ref. https://doi.org/10.1038/jid.2012.177 rich in lipid substances  LO6: Discuss the 3 pigments most responsible for producing the various skin colors. Inside keratinocytes, melanosomes are most numerous in areas over the nuclei, creating “dark red+yellow hues umbrellas” that protect the nuclear DNA from the Eumelanin & pheomelanin sun’s harmful ultraviolet (UV) radiation. Brown-black shades Melanin, carotene, and yellow-orange pigment hemoglobin obtained from dietary determine skin Organelles where sources like carrots color melanin is produced. They are transported to neighboring keratinocytes through cytoplasmatic extensions Hemoglobin contributes to a subtle reddish undertone depending on blood flow - noticeable in areas where the skin is thinner (lips) Image credit: "Skin Pigmentation" by Scientific Animations is licensed under Creative Commons “BY-SA 4.0 International".) Fig. Pearson, Inc.  LO7: Identify the dermis layers, including the tissue types making up each dermal layer. The dermis is the underlying connective tissue Epidermal ridges framework that supports the epidermis Well supplied with blood vessels, lymphatic vessels, and nerves. Dermal papillae Contain cutaneous receptors, glands, & The papillary layer forms hair follicles. finger-like projections into the epidermis, known as 2 Layers: dermal papillae Areolar (loose) Dermal ridges and epidermal ridges together form the friction ridges: impressions on the skin's surface, present on our fingers, toes, palms, and soles. They ↑surface area for better grip. Dense irregular Fingerprints are the unique patterns formed by friction ridges on our fingertips and thumbs. Ifig. PEARSON, Inc.mage credit: "Layers of the Dermis @100x" by Jennifer Lange is licensed under CC-BY-NC-SA 4.0  LO8: Describe the general structure and functions of the subcutaneous layer It lies between the dermis and underlying organs. It is composed of a mixture of two main types of connective tissue: loose areolar tissue and adipose tissue--they are interwoven throughout the layer.  The proportions of these two tissues can vary depending on location in the body Superficial fat layer Hypodermis dense connective tissue sheath (superficial fascia or subcutaneous layer) Deep fat layer envelops all the muscles of the body Deep fascia Thermal Insulator -poor conductor of heat (traps heat generated by internal organs and muscles and prevents its transfer to the surrounding environment through the skin) Stores Energy (TGs). Act as a Shock Absorber--cushion impacts (due to soft, gel- DOI:10.1055/s-0042-1757322 like nature of fat cells) Stecco, C., Macchi, V., Porzionato, A., Duparc, F., & De Caro, R. (2011). The fascia: the forgotten structure. Italian journal of anatomy and embryology = Archivio italiano di anatomia ed embriologia, 116(3), 127–138.  LO9: Indicate the location and function of the sudoriferous glands (sweat glands) Sweat pore Their ducts empty their secretion onto the skin surface via sweat pores Hair follicle Ducts lead to nearby hair follicles Apocrine sweat gland Eccrine (merocrine) sweat gland present in the axilla Distributed over the entire body and pubic area surface (a few exceptions). coiled tubular Simple coiled tubular glands that glands with large secrete a salt solution containing lumen that are small amounts of other solutes. associated with hair follicles Function: thermoregulation. produce milky protein-rich sweat  LO10: Indicate the location and function of the sebaceous glands. They occur all over the body surface except for the palms and soles. They are part of the pilosebaceous unit, including the hair, hair follicle, and arrector pili muscle--- their ducts usually empty into hair follicles (holocrine mode of secretion: cell dies) They are activated (at puberty) and controlled by androgens. Oily substance, a mixture of lipids that forms a thin film on the skin. Sebum lubricates the skin and hair, prevents water loss from the skin, and acts as a bactericidal agent.  LO11: Describe the anatomy of the nails The visible portion, rests on the nail bed. Made up of a dense network of keratin filaments and remnants of cells plus calcium salts. the skin that surrounds Free Edge -the tip of the nail that extends beyond the fingertip the entire nail plate Perionychium White, half-moon shape, located at the base Lunula Lateral fold thick corneal layer (dead cells) of the eponychium that overlaps the thick, hard skin located the base of the nail plate beneath the free edge Nail plate Eponychium the thickened layer of skin at the base of the nails Onychium refers to the entire area where the skin interacts with the nail plate. matrix It's further divided into 3 sections based on their location around the nail. The technical name for the nail is Onyx – used as a prefix to names given to nail disorders.  Anatomy of the basic parts of a human nail is the portion of the matrix that can be seen through the transparent nail plate nail plate lunula sinus root free margin hyponychium nail bed matrix This is the skin beneath the nail plate that is attached to the underlying bone. Responsible for the growth of the nail plate: this is the It is richly supplied with blood vessels, which give live tissue where new nail cells are produced, pushing the nail its pink color. KDS444, CC BY-SA 3.0 , via Wikimedia Commons old cells out distally.  LO12: Describe the general structure of the hair and its associated structures Hair is derived from the epidermis Hair shaft part of the hair above the surface of the skin Hair root Hair follicle part of the hair complex epithelial invagination (sac-shaped) originating in the below the surface epidermis and extending deep into the dermis in which hair grows. Hair bulb Enlarged, hollow portion at the base of the root Contains a matrix -actively divides to extend the hair shaft vertically (Image credit: "Hair Follicles and Hair" by Jennifer Lange is licensed under CC BY-NC-SA 4.0, modification of original by Scientific Animations.) The hair has three layers: central core made of loosely arranged cells and air spaces flat overlapping cells in a scale- like formation thickest, made by several layers of cells that contain hard keratin Types of pigment granules in these cells give hair color Eumelanin (brown/black); pheomelanin (red and blond) Hair consists of dead, keratinized cells  5 Mineralization (mineral deposition): process in which calcium, phosphate, and other ions are 4 taken from blood and deposited in bone Formation: when osteoblasts lay down new bone until the resorbed bone the osteoblasts is completely replaced turn into the flat “bone builders” (Quiescence) endosteal lining cells or into osteocytes if trapped in the newly formed bone. One remodelling cycle takes approximately 120 days © Biomedical Tissue Research, University of York DOI: 10.1196/annals.1365.035  LO9: Summarize the 4 stages of fracture repair (healing process) by endochondral ossification. 1. Hematoma formation & 2. Soft callus (3) Bony (hard) (4) Bone remodeling Inflammatory response (cartilage) Callus Formation (Immediately after the fracture) formation Continues for months to years White blood cells are recruited to replace woven remove any dead (immature) bone cells and debris. with lamellar Cartilage of the (mature) bone. calluses is blood vessels are damaged→ gradually blood accumulation. eroded by osteoclasts Granular tissue: and replaced A temporary by trabecular connective tissue bone, forming containing new blood the hard callus. vessels, fibroblasts, and inflammatory cells, involved in wound healing and inflammation https://open.oregonstate.education/aandp/chapter/6-5-fractures-bone-repair/ Morgan, Elise & Lei, Jenny. (2015). Toward Clinical Application and Molecular Understanding of the Mechanobiology of Bone Healing. Clinical Reviews in Bone and Mineral Metabolism. 13. 10.1007/s12018-015-9197-6.  (plural calluses or calli) External callus Composed of a mix of hyaline cartilage and woven bone*. Formed by periosteal chondrocytes and osteoblasts around the outside of the break *Woven Bone: A temporary, immature bone tissue with a less organized structure compared to mature lamellar bone Internal callus Primarily composed of fibrocartilage: a hybrid tissue combining features of fibrous tissue (collagen fibers) and hyaline cartilage. Formed by chondrocytes from the endosteum by secreting a fibrocartilaginous matrix between the two ends of the broken bone. LO10: Analyze the formation of external and internal calluses during stage 2 of fracture repair, including their compositions and the cells involved in their formation.  LO11: Identify the key systemic hormones that regulate bone metabolism and their primary effects. main function: maintain blood calcium homeostasis. Parathyroid-H (PTH) Calcitriol (Active Vitamin D) (+) Intestines to absorb calcium from digesting food Calcitonin (-) bone breakdown Calcium Regulating (+) both bone-resorbing and bone- Hormones forming cells, but the dominant effect Estrogen Other is on bone formation: ↑bone mass. Systemic Testosterone Hormones Growth hormone (GH) & Insulin-Like Growth Factor (IGF) Sex hormones Thyroid hormone (+) bone formation Cortisol ↑ energy production of all body cells, incl.bone cells. ↑ rates of both bone formation & Small amounts are necessary for resorption. normal bone development, but large amounts block bone growth https://www.ncbi.nlm.nih.gov/books/NBK45504/  LO12: Explain the interplay between bone remodeling and hormonal regulation in maintaining calcium homeostasis Bones act as the body's primary reservoir for Calcium homeostasis is mainly controlled calcium where it is stored in the mineralized bone by the skeleton, the gut, and the kidney. matrix as hydroxyapatite (calcium phosphate). (1) When blood calcium levels decline, PTH is released by the parathyroid gland. PTH (+) osteoclasts to digest bone matrix, releasing ionic calcium. Net effect: PTH (& calcitriol) ↑ blood PTH (+) kidney tubule cells calcium levels when they drop too low. to recover waste calcium from the urine. PTH (+) kidney tubule cells to release calcitriol which ↑ calcium absorption from intestines into the blood Gwadera, Ł., Białas, A.J., Iwański, M.A., Górski, P., & Piotrowski, W.J. (2019). Sarcoidosis and calcium homeostasis disturbances—Do we know where we stand? Chronic Respiratory Disease, 16.  Hight concentrations of calcium stimulates the thyroid gland to release calcitonin This creates a relative ↑ in bone formation activity over time (up On the flip side of PTH, calcitonin taking Ca2+ from the blood to reduces blood calcium levels deposit into bone) when they get too high. By inhibiting osteoclastic activity and promoting calcium deposition back into bones, calcitonin indirectly helps regulate calcium excretion in the kidneys. Gwadera, Ł., Białas, A.J., Iwański, M.A., Górski, P., & Piotrowski, W.J. (2019). Sarcoidosis and calcium homeostasis disturbances—Do we know where we stand? Chronic Respiratory Disease, 16. doi:10.1152/physrev.00066.2017  L10: Menu Joints LO1 Section A: Classification LO2-3 Section B: Structure LO4-5 Section C: Movement 206 bones connected by 360 joints Joints, or articulations, are sites where bones meet. Their functions are to hold bones together and to allow various degrees of skeletal movement. ©Beatriz Castro Joint name: typically derived from the names of the bones involved (e.g., radioulnar joint) Other references: @ProfessorDaveExplains YouTube Channel, Human Anatomy & Physiology, 11th edition, Published by Pearson (July 6, 2021) © 2019 Elaine N. Marieb  LO1: Describe the functional and structural joint classification. Provide examples. according to the way bones based on degree of are bound to each other movement allowed (most) -bones are -bones connected have a fluid-filled Synarthrotic Amphiarthrotic Diarthrotic connected by by cartilage joint cavity Immovable Little movement Full movement fibrous tissue Symphyses Gliding Synovial joints Gomphoses (amphiarthrotic) Hinge Syndesmoses Contain Ball & socket Sutures fibrocartilage Pivot Ellipsoid (synarthrotic) Synchondroses Saddle (synarthrotic) (diarthrotic) Contain hyaline cartilage https://www.geeksforgeeks.org/types-of-joints/ https://www.youtube.com/watch?app=desktop&v=DWpOYNomoRI&ab_channel=Well-KnownReyes  Fibrous Joints Gomphoses Syndesmoses Sutures peg-in-socket joints, where a two bones are bound by long collagen fibers bind the bones cone-shaped structure (peg) fits collagen fibers (ligaments) of the skull to each other into a depression (socket). The fibrous tissue ossifies during middle age→bones fuse into 1 single unit (synostoses). anchors each tooth to its bony socket within the jaw Examples include the connection between the tibia and fibula, and the radius and ulna Copyright © The McGraw-Hill Companies, Inc  Cartilaginous Joints Symphysis Synchondrosis Bones are joined by fibrocartilage Bones are joined together by hyaline cartilage, or where bone is united to hyaline cartilage The bodies of adjacent vertebrae are joined together by fibrocartilage Image credit: "Symphysis Joints - Intervertebral Discs" by Jennifer Lange is licensed under CC BY-NC-SA 4.0, modification of image from Anatomy Standard under CC BY-NC 4.0. (Image credit: "Amphiarthrosis - mage credit: "Synchondrosis - Epiphyseal Plate" by Jennifer Lange and Justin Greene is licensed under CC Pubic Symphysis" by Jennifer Lange is licensed under CC BY-NC-SA 4.0, modification of image from BY-NC-SA 4.0, modification of original by OpenStax Anatomy Standard.)  LO2: Identify the structural components of the synovial joint and associated structures. Bones are separated by fluid-containing joints cavity. This arrangement permits diarthroses. Synovial fluid: derived by filtration of the blood. Viscous, egg-white consistency due to hyaluronic acid. ↓ Friction b/w cartilages. Lubricates and nourishes (inner layer of the joint capsule) articular cartilage It produces synovial fluid –Provides oxygen and Hyaline nutrients to chondrocytes Protect the ends of the bones –Carries away metabolic wastes Tough fibrous tissue structure that surrounds the synovial joints. It adds strength and protects the synovial membrane underneath. https://www.teachpe.com/anatomy-physiology/structure-of-a-synovial-joint https://www.slideshare.net/slideshow/nikku-pdf-on-joints/88358144#20  Ligament: strip of collagenous tissue attaching one bone to another Some synovial joints (e.g., the Generally white in appearance. knee) contain articular discs that absorb shock: Ligaments prevent undesirable movements and reinforce the joint. Pad of fibrocartilage between opposing bones in a synovial joint. Purpose: to add support and cushioning to the joint. Articular surfaces providing the most stability have large surfaces and deep sockets and fit snugly together.  A bursa is a small sac of synovial fluid found in the structure of all synovial joints. Positioned between the tendon and the bone its purpose is to lubricate the movement of the tendon over the bone. strip of The tone of muscles collagenous whose tendons cross tissue attaching the joint is the most muscle to bone important stabilizing factor in many joints.  Bursae and Tendon sheaths in the shoulder joint Bursa eliminates friction where a Both allow adjacent structures to move smoothly over one another. ligament (or other structure) would rub against a bone Bursae (plural)= flattened fibrous scapula sacs lined with synovial mb and ligament containing synovial fluid bursa Fibrous articular capsule Tendon sheath Tendon sheaths = elongated cylindrical bursa wrapped around a tendon tendona tendon (hotdog) Frontal section through the right shoulder joint located between muscles, where tendons or ligaments pass over bone, or b/w bone and skin LO3: Understand the distinctions between the three types of connective tissues found within or close to joints: cartilage, ligaments, and tendons. Within the joint cavity: at end of bone. Form a cushion b/w bones in order to stop them rubbing. They are not directly Flexible. part of the joint itself. Attach muscle to bone (anchor). Transmit the pulling Outside the joint cavity, surrounding the force of muscles to joint capsule. bones, allowing for Attach bone to bone. controlled movement. Very strong string (made of dense, tightly Similar composition packed collagen fibers) that hold bones as ligaments. together →prevent bones from moving beyond their intended range of motion. https://orthoinfo.aaos.org/en/diseases--conditions/rheumatoid-arthritis/  LO4: Indicate the movements allowed by synovial joints. Range of motion (ROM) of a joint is the extent or limit to which a body part can be moved around a joint--- In other words, it's how much you can move a particular joint.  Synovial joints differ in their range of motion The structure of a synovial joint determines the potential for movement based on its axes and planes: nonaxial (slipping movements only), uniaxial (in 1 plane), biaxial (in 2 planes), and multiaxial (in or around all 3 planes) movements. Greater range of motion results in weaker joint When a skeletal muscle contracts, the insertion (movable attachment) moves toward the origin (immovable attachment). Muscle contractions across a joint translate that potential into actual movement, categorized as gliding, angular, or rotational.  https://tommorrison.uk/blog/anatomical-movements Angular movements the movement of the limb, hand, or fingers in a circular pattern Moving towards Moving the away midline axis from the Rotation midline Turning a bone around its own axis, toward midline or away from it Gliding or Gliding movement Plane joint Adduction Abduction  Special movements include: Wrist-forearm Refer to the radius Refer to movements in the moving around the ulna mandible pushes the chin forward Plantarflexion pulls the chin back Refer to the down- and up- movement of the Dorsiflexion ankle, respectively. https://doi.org/10.3390/app12126164 https://open.oregonstate.education/aandp/chapter/9-5-types-of-body-movements/#:~:text=Circumduction%20is%20the%20movement%20of,%2C%20metacarpophalangeal%2C%20and%20metatarsophalangeal%20joints. LO5: Describe the anatomical features, locations in the body, and type of movements associated with each of the six structural types of synovial joints. Synovial joints are classified into 6 categories based on the shape of their articular surfaces (the areas where bones meet within the joint). The shape of these surfaces dictates the type and range of movement allowed at the joint. 1 Formed when two (nearly) flat surfaces of bones articulate. Minimal movement--Strong ligaments link them together and stop them moving to far. Nonaxial movement. Intercarpal Gliding joint Intertarsal e.g. the bones in your wrist past sliding each other slightly, allowing for subtle adjustments in hand position.  2 This joint functions like a hinge on a door that we would only be able to open or close in one direction or in one plane. Humerus The most important factor contributing to joint stability is highly complementary articular surfaces. The humeroulnar joint of the elbow in which Hinge Joint the ulna (and radius) articulates with the humerus, allowing flexion and extension. The knee joint is a hinge joint formed by the articulation of the tibial and femoral condyles (and anteriorly by the patella and patellar surface of the femur). Extension, flexion, and (some) rotation are Picture:https://lermagazine.com/article/kicking-biomechanics-importance-of-balance allowed.  3 It allows only rotation (pivot) motions in the transverse plane around a vertical axis (unixaxial). e.g. The proximal radioulnar joint that occurs between the head of the radius and a small Pivot Joint indentation on the ulna called the radial notch. (Image credit: Getty Images) e.g. the atlantoaxial (C1-C2) joint of the spine between the atlas and axis--- This allows us to turn the head. The end of one bone has a “peg” which fits into a “ring” formed by the other bone. https://courses.lumenlearning.com/wm-biology2/chapter/types-of-synovial-joints/ https://musculoskeletalkey.com/2-the-skeletal-system/  4 Also known as an ellipsoid joint Formed when an oval shaped surface fits within the ellipsoidal socket or cavity. Biaxial with angular movements in two planes radius Creates an ellipsoidal socket radial carpal joint Proximal carpals--oval shaped wrist Metacarpal phalangeal joints  5 Occur where concave and convex surfaces meet. Biaxial, like condylar joints, but with freer movement. e.g. sternoclavicular joint where the convex surface of the clavicle meets the concave surface of the sternum Warth, R.J., Millett, P.J. (2015). The Sternoclavicular Joint. In: Physical Examination of the Shoulder. Springer, New York, NY. https://doi.org/10.1007/978-1-4939-2593-3_8  6 In this type of joint, one end of the bone is shaped like a ball, and it fits into a hollow socket at the end of another bone. Multiaxial: allow for multi-directional and rotational motion Of all the joints in the body, this type allows the greatest range of movement. hip joint Glenohumeral joint (shoulder) acetabulum formed by the acetabulum of the hip bone and the femoral head. (cavity) formed by the glenoid cavity of the scapula and the humeral head. The most freely movable Getty Images Lead photo by Mark J. Rebilas-USA TODAY Sports joint of the body. https://www.youtube.com/watch?app=desktop&v=DWpOYNomoRI&ab_channel=Well-KnownReyes