Exam 2 (3) PDF - Biology Past Paper

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  Hair follicle Hair shaft Companion layer (single-cell layer) Outer Root Sheath Inner Root Sheath They are mixed amongst the matrix cells. They transfer melanosomes to the keratinocytes within the growing hair shaft to provide it with color. bulb Melanocytes matrix -Projection of dermis into center of bulb Dermal Papilla - Secretes various growth factors Matrix cells -Richly vascularized- delivery of oxygen and essential nutrients to the hair matrix & receive hormones Act as germ cells-As the matrix cells continue to divide, they will eventually differentiate into the internal root sheath and keratin-producing cells (i.e., hair shaft cuticle and cortex layers) Jadeja, Shahnawaz & Tobin, Desmond. (2022). Autoantigen Discovery in the Hair Loss Disorder, Alopecia Areata: Implication of Post-Translational Modifications. Frontiers in Immunology. 13. 1. 10.3389/fimmu.2022.890027. https://doi.org/10.1007/978-3-319-37076-7_12-1  LO13: Describe the growth cycles of hair follicles and the growth of hairs. ~ 80% hair in scalp at any given time. --a period of growth in which a new hair develop Projection of the external root sheath near insertion of the arrector pili muscle forms the FOLLICULAR BULGE that contains epidermal stem cells. Epidermal stem cells that reside in the follicular bulge migrate downward to reach the hair matrix in the bulb of the follicle. As the differentiation progresses, cells leave the matrix; they form cell layers that differentiate into the hair shaft & inner root sheath. Each strand of hair on the human body is at its own stage of development. Hair generally categorizes into hormone-dependent, thicker terminal hairs in regions such as the axilla, pubic areas, scalp, chest, etc., and androgen-independent vellus hairs that cover the rest of the areas. https://doi.org/10.1007/978-3-319-37076-7_12-1  ~10 days Regression Phase --brief period in which growth stops (cell division ceases) the hair matrix regresses, the dermal papilla ~2-8 yr (scalp) retracts, capillary nourishment diminishes, and entire Shorter for follicles retract toward the epidermal layer. Growth Phase eyebrow and pubic hair ~3 mo --long rest period in which the follicle Resting Phase atrophies, and the hair shaft is eventually lost (poor nutrient supply) This makes room for a new shaft that will grow during anagen regeneration. transitory structure Follicle cells that survived catagen + bulge-derived cells When these cells become activated by growth signals, they initiate the anagen phase  Lecture 8: Skeletal System I (A) General functions & Organization of the skeletal system LO1-2 (B) Axial skeleton LO3-6 (C) Appendicular skeleton LO7-8 FPPT.com (D) Gross anatomy of bones LO9-12 (E) Microscopic anatomy of Osseus tissue LO13 Other references: https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Human_Anatomy_%28Lange_et_al.%29/06%3A_Axial_and_Appendicular_Skeleton/6.03%3A_The_Skull https://teachmeanatomy.info/the-basics/ultrastructure/bone/  LO1: State the major functions of the skeletal system. The human skeletal system e.g. the skull protects the brain, and the rib consists of bones, cartilage, cage protects the heart and lungs. ligaments and tendons and accounts for about 20% of the body weight. hematopoiesis (occurs in bone marrow) phosphorus The muscles attach to the bones at tendons, and when the muscles contract, they pull on the bones, causing movement. body --allowing us to stand upright. body organs https://training.seer.cancer.gov/anatomy/skeletal/ LO2: Indicate the two major divisions of the skeletal system (axial and appendicular) and list the general bone structures contained within each. About 206 bones (adult) 2 Main Divisions It forms the longitudinal axis of the body. It consists of the bones of the pectoral Its principal subdivisions and pelvic girdles and the limbs. are the skull, It allows mobility for manipulation and vertebral column, and locomotion. thoracic cage. These bones serve as the base for the It provides support and muscles to attach to create movement. protection (by enclosure). https://www.scientistcindy.com/the-appendicular-skeleton.html Axial Skeleton It is formed by 22 bones. Except for the temporomandibular joints, all bones of the adult skull are joined by sutures (immovable joint) (thoracic cage) 12 pairs of ribs protects the heart, lungs, and other vital 33 vertebrae organs in the chest cavity. provides structural support, houses the spinal cord LadyofHats Mariana Ruiz Villarreal  LO3: Identify the skull bones (22) protect the brain (8) Parietal (2) Temporal (2) frontal, occipital, (14) ethmoid, sphenoid provides openings for the respiratory and digestive passages and attachment points for facial muscles. (Image credit: "Lateral View of the Skull" by Mark Schaeffer is licensed under CC BY-NC-SA 4.0, modification of images from Anatomy Standard under CC BY-NC 4.0.) (Image credit: "Bones of the Skull - Lateral View" by Jennifer Lange is licensed under CC BY-NC-SA 4.0, modification of image from Anatomy Standard under CC BY-NC 4.0.) )  form the external superior surface of Palatine bones (2): These the nose contribute to the hard 2 palate Lacrimal bones (2) -- contribute to the formation of the tear duct. Vomer: flat, triangular cheekbones bone, forms the back of the nasal cavity and inferior portion of the nasal septum (the partition separating the Inferior nasal conchae (2) nostrils). (turbinates): located within the nasal cavity; help warm, (2) humidify, and filter inhaled air. These bones form the upper jaw and house the upper teeth The lower jawbone the only movable bone in the facial skeleton--responsible for chewing and speaking. (Image credits: "Cranial Bones" and "Facial Bones" by Mark Schaeffer are licensed under CC BY-NC-SA 4.0, modification of images from Anatomy Standard under CC BY-NC 4.0.)  LO4: Identify bone markings (anatomical landmarks) in the skull  They reveal sites of muscle attachment, points of articulation, and sites of blood vessel and nerve passage. supraorbital foramen infraorbital foramen Air-filled space in bone Sinus (pl. foramina) International Journal of Morphology. 40. 181-187. 10.4067/S0717-95022022000100181. mental foramen Foramen Hole through bone through which nerves and blood vessels pass. Canal Fissure Slit through bone Passage in bone usually houses nerves and blood vessels. e.g. e.g. superior and inferior orbital fissure. optic canal OC optic canal, SOF superior orbital fissure, IOF inferior orbital fissure https://open.oregonstate.education/aandp/chapter/7-2-bone-markings/ https://link.springer.com/article/10.1007/s00276-020-02573-w  Process A bulging bony outgrowth of a larger bone Mastoid process --it's a bony projection that arises from the temporal bone many head muscles are attached to it Fossa A shallow depression in the bone surface. Here it may receive another articulating bone or act to support brain structures. Bandovic, I., Holme, M. R., Black, A. C., & Futterman, B. (2023). Anatomy, Bone Markings. In StatPearls. StatPearls Publishing.  Curvatures 7 LO5: Discuss the anatomy of the vertebral column and ↑ spine vertebrae. Identify bone markings in the vertebrae flexibility includes 24 12 movable vertebrae fibrocartilage intervertebral discs act as shock absorbers and provide flexibility https://www.sci-info-pages.com/anatomy-of-the-spine/ LO6: Discuss the anatomy of the thoracic cage It is the bony structure of the chest-- manubrium protects the organs of the thoracic cavity. The bones of the thoracic cage include: 12 rib pairs, body the sternum, the thoracic vertebrae. Xiphoid process The first seven rib pairs are called true ribs false ribs floating ribs https://humanbodylearning.com/rib-cage-anatomy-function/