NURS 207 (N01) Integumentary System Lecture Notes September 16, 2024 PDF

NURS 207 (N01) Integumentary system Epidermis: structure and functions Reading materials (textbook): Tortora, 16th ed., Ch. 5 September 16, 2024 Dr. P. Lee  Objectives 1) Describe the layers of the epidermis a...

NURS 207 (N01) Integumentary system Epidermis: structure and functions Reading materials (textbook): Tortora, 16th ed., Ch. 5 September 16, 2024 Dr. P. Lee  Objectives 1) Describe the layers of the epidermis and the cells that compose them 2) Compare the composition of the papillary and reticular regions of the dermis 3) Contrast the structure, distribution, and functions of hair, skin glands, and nails  Introduction Integumentary system: skin and its accessory structures Skin colour can review some aspects of physiology Blushing → related to the status of our emotion Bluish lip → related to hypoxia (lack of oxygen) Pale & clammy → usually related to an increase in sympathetic tone (high anxiety, nervous, tense) Yellowish color → Jaundice ▪ When excess bile pigments accumulate in the blood ▪ Sign of possible hepatic damage  Introduction Dermatology Study of integumentary system which encompassing → Skin which is the cutaneous membrane → Accessory structures  Integumentary system Accessory structures of the integumentary system include: ✓ Hair ✓ Nails ✓ skin glands → oil → wax → sweat → mammary – milk secretion ✓ sensory receptors → For the detection of pain, sensation, pressure, and temperature  Basic structure of the skin Skin (cutaneous membrane) → Largest organ by weight in our body → With ≈ 2 m2 surface area for an average adult  Basic structure of the skin Skin (cutaneous membrane) → 2 layers: epidermis & dermis Epidermis: → As epithelial tissue Epidermis → Consists of multiple cell layers (stratified epithelium) that create a protective barrier → This skin layer is avascular (no blood vessels)  Basic structure of the skin Epidermis: → Contains 4 main cell types 1) Keratinocytes ✓ Majority of the epidermal cells ≈ 90% ✓ Produce the tough fibrous protein keratin → Protect underlying tissues from abrasions, heat, microbes, and chemicals ✓ Also produce lamellar granules (keratinosomes) which release lipid rich secretion that serve as water repellent sealant and function as a barrier to prevent the entry of foreign materials  Basic structure of the skin Epidermis: 1) Keratinocytes ✓ Some of the keratinocytes located in the deepest layer (stratum basale) are served as stem cells → Keep producing keratinocytes ✓ These cells move toward the superficial surface and begin the process of apoptosis (cell death) → As apoptosis progress, regression of organelles and flatten in size as they move farther from their source of nutrient (epidermis is avascular)  Basic structure of the skin Epidermis: 1) Keratinocytes ✓ As the newly formed keratinocytes push from the stratum basale toward the outer layer of the epidermis, more keratin is accumulated → Process known as keratinization → Since the epidemic layer is avascular, nutrients and oxygen are received from the blood vessel within dermis by diffusion  Basic structure of the skin Epidermis: 2) Melanocytes ✓ ≈ 8% of the epidermal cells ✓ found in the basal section of the skin’s epidermis ✓ Produce the pigment melanin and package within the melanin granules → Melanin gives skin color → It absorbs the harmful UV radiation and prevents damaging DNA  Basic structure of the skin Epidermis: 2) Melanocytes ✓ Melanin granules containing melanin are carried by the dendrites of the melanocyte and reach over the keratinocytes → Melanin granules cluster form a veil over the keratinocytes → Protect the keratinocyte’s DNA from UV damage  Basic structure of the skin Epidermis: 2) Melanocytes ✓ Exposure to UV light causes an increased in melanogenesis (production of melanin) → A process that can induce tanning Melanin is a yellow-red to brown-black pigment (contributes to skin colour)  Basic structure of the skin Epidermis: 3) Intraepidermal macrophages ✓ Also known as Langerhans cells ✓ Small fraction in population within the epidermal cells → Function as immune cells → Recognize invading microbes and destroy them  Basic structure of the skin Epidermis: 4) Tactile epithelial cells ✓ Also known as Merkel cells ✓ Least numerous in population within the epidermal cells ✓ With contact to the tactile/Merkel disc of the sensory neuron (nerve cells ) → Tactile epithelial cells’ function is to detect touch sensations  Basic structure of the skin ❖ 2nd layers: dermis Dermis → Thicker than epidermis Dermis → With connective tissues containing collagen and elastic fibers → Contains exocrine glands, blood vessels, muscles, and sensory receptors and nerve endings  Dermis: Sebaceous gland Exocrine glands Sweat gland Dermis Apocrine gland  Dermis: Blood vessels Dermis Artery Vein With blood vessels extend upward into the dermis  Dermis: Muscles Dermis Contraction of arrector pili muscles pull hair follicles into a vertical position, creating “goose bumps”  Dermis: Sensory receptors and nerve endings Sensory receptors and nerve ending monitor external conditions Dermis Sensory nerve  Integumentary system Hypodermis: Consists of loose connective tissue with collagen and elastin fibers Main types of cells are fibroblasts (important for wound healing), adipose cells, and macrophages Hypodermis Hypodermis is also known as subcutaneous layer and is not part of the skin Approximately ½ of the body adipose tissues are located within the hypodermis (energy and insulation) Two regions of the dermal layer  Two regions of the dermal layer Have 2 main regional layers within the dermis a) Papillary region Papillary region → Just beneath the epidermis → With nipple- shaped structures (dermal papillae) that project into the undersurface of the epidermis a) Papillary region Capillary loops → Surface area that in direct contact with the epidermis is greatly increased by dermal papillae → All dermal papillae contain capillary loops  The existence of dermal papillae and capillary loops are essential to the survival of the epidermis because epidermis receive its supplies from the connective tissues below through diffusion  Meissner corpuscle a) Papillary region → Some area of papillary region contains tactile receptors called corpuscles of touch or Meissner corpuscles which are sensitive to touch free nerve endings → Papillary region also contain free nerve endings give rise to sensations of temperature, pain, tickling, and itching b) Reticular region → Located between the papillary region and the subcutaneous layer → With bundles of thick Reticular collagen fibers and region some coarse elastic fibers in the ground substance  Collagen fibers help the skin resist stretching b) Reticular region → Also contains fibroblasts, macrophages, and some adipose cells → With blood vessels, Reticular nerves, hair follicles, region sebaceous (oil) glands, and sudoriferous (sweat) glands  Structure, distribution, and functions of accessory components of the skin (hair, skin glands, and nails)  Accessory components of the skin Hair  Accessory components of the skin Hair → Protective function offers by the hair is limited → Function in sensing light touch  Accessory components of the skin Hair → Composed of columns of dead, keratinized epidermal cells → Hair root is the portion of the hair deep to the shaft that penetrates into the dermis, and sometimes into the subcutaneous layer  Accessory components of the skin Hair → Consist of three concentric layers of cells: medulla, cortex, and cuticle of the hair → Inner medulla contain pigment granules ▪ Large amount in dark hair ▪ Small amounts of pigment granules in gray hair ▪ Lack of pigment granules and the presence of air bubbles in white hair  Accessory components of the skin Hair → Middle cortex forms the major part of the shaft → Outermost layer (cuticle) consists of a single layer of thin, flat cells that are the most heavily keratinized  Sebaceous gland that Skin glands secrete a lipid mixture (sebum) to keep skin moist Sweat (sudoriferous) gland secretes a dilute salt fluid to cool the body Dermis Apocrine gland releases secretions in response to fear or excitement (body odor)  Skin glands → Ceruminous glands ▪ Modified sweat glands in the external ear ▪ Produce a waxy lubricating secretion ▪ With excretory ducts open either directly onto the surface of the external auditory canal (ear canal) or into ducts of sebaceous glands ▪ Combined secretion of the ceruminous and sebaceous glands is a yellowish material called cerumen, or earwax ▪ Main function is to impede the entrance of foreign bodies and insects Nails  Nails → Tightly packed, hard, dead, keratinized epidermal cells → Below the nail body is a region of epithelium (with cells that divided into new nail cells) and dermis a deeper layer of epithelium dermis → The whitish area of the proximal end of the nail body is called the lunula ▪ Due to the thickened region of epithelium, vascular tissue underneath does not show through  Sample questions 1) Choose the correct statement that describes keratin correctly. a) Keratin participates in immune responses b) Keratin is used for pigmenting skin c) Keratin is the fibrous protein produced by keratinocytes d) Keratin protects the skin from UV light damage 2) Which of the followings is secreted by specialized cells in the skin that is capable of absorbing ultraviolet light? a) Melanin b) Carotene c) Melatonin d) Hemoglobin  Sample questions 3) Which of the following structures found in the skin has the function to prevent water loss on the surface of the skin? a) Arrector pili muscle b) Lamellar granules c) Melanin granules d) Intraepidermal macrophages 4) Which structure found in the skin plays an important role in thermoregulation? a) Melanocytes b) Sebaceous glands c) Sweat (sudoriferous) glands d) Adipose tissues  Sample questions 5) Which of the following statements is CORRECT? a) Dermal papillae and capillary loops are located within the epidermal layer of the skin that supply the oxygen and nutrients to the epidermis b) Hypodermis is the inner layer of the skin c) Melanin gives skin color d) All the cells within the epidermal layer of the skin are dead cells because this layer is avascular 6) “Goose bumps” are caused by a) contraction of arrector pili muscles b) secretions from the sudoriferous glands c) contraction of dermal papillae d) stimulation of hair root plexus  Answer to sample questions 1) c 2) a 3) b 4) c 5) c 6) a