Vertebrate Integumentary System PDF

VERTEBRATE INTEGUMENT ARY SYSTEM INTEGUMENT The outer covering of the body of vertebrates. Includes the mucous membranes. Forms the interface between organisms and the external environment.  Structure of Epithelial tissue stratified...

VERTEBRATE INTEGUMENT ARY SYSTEM INTEGUMENT The outer covering of the body of vertebrates. Includes the mucous membranes. Forms the interface between organisms and the external environment.  Structure of Epithelial tissue stratified skin squamous (keratinized) Basement membrane Loading… glue-like layer Epidermis Dermal-epidermal junction Connective tissue dense, fibrous Dermis connective tissue blood vessel, nerves, etc. Areolar & Hypodermis adipose tissue superficial fascia subcutaneous tissue  FUNCTIONS OF THE SKIN Protective barrier (mechanical, chemical, bacterial, UV (thermal damages), and desiccation. Cutaneous receptors. Temperature regulation Excretion (sweat) Vitamin D synthesis  EMBRYONIC ORIGIN AND DEVELOPMENT EPIDERMIS – ectoderm origin Loading… DERMIS – mesoderm origin HYPODERMIS – mesoderm origin EPIDERMIS Made up of stratified squamous layer of epithelial tissues. Layers consist of: Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum germinativum/basale EPIDERMAL CELLS KERATINOCYTES- 90% of epidermal cells; produce keratin. MELANOCYTES- 8 % of epidermal cells; produce melanin LANGERHANS CELLS- capable of trapping antigen in the skin. MERKEL CELLS- make contact with the ending of a sensory neuron. DERMIS Contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. Consists of loose connective tissue otherwise called areolar connective tissue - collagen, elastin and reticular fibers are present. Provides tensile strength, and physiologic support for the interfacing epidermis HYPODERMIS The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. Fat serves as padding and insulation for the body. CHROMATOPHORE S Provides concealing coloration to the integument Various colors are produced by combinations of different chromatophores and by different Loading… degrees of dispersion of pigment granules. Skin color also depends on the background color of the stratum germinativum Some vertebrates have the ability to change color (metachrosis/metachromatosis), controlled by the endocrine and the nervous system.  TYPES OF CHROMATOPHORES MELANOPHORES Produce yellow, brown to black pigment. Melanin protects chromosomes in the S. basale from UV lights. FRECKLES and MOLES – melanin is concentrated in one spot.  LIPOPHORES Carotenoids (yellow, orange, red pigments) Xanthophores – yellow Erythrophores – red IRIDOPHORES or GUANOPHORES Causes iridescence in vertebrates (fishes) Contains guanin (purine) crystals  GLANDULAR EPITHELIUM Refers to a type of epithelial tissue involved in the production and release of different secretory products, such as sweat, saliva, breast milk, digestive enzymes, and hormones, among many other substances. EXOCRINE GLAND - are glands that secrete substances onto an epithelial surface by way of a duct.  CLASSIFICATION OF UNICELLULAR EXOCRINE Club cells GLAND Elongated, binucleated (amphibians) Secretes mucus May contain chemicals that stimulates alarm or fear Granular cells Secretes mucus in skin (lampreys and other fishes) Goblet cells Narrow apical end, wide base (osteichthyes and chondricthyes) Secretes mucus Sacciform cells  Secrete large, membrane- Types of multicellular glands: Tubular Glands Types Characteristics Examples 1. Simple Tubular -short, blind tubes located in the -thumb pads (anurans) dermis and extend to the surface -ceruminous glands 2. Simple Coiled -long, narrow tube, coiled distal -sweat glands end located in the dermis -openings are referred to as pores of the skin 3. Simple -divides at its distal ends into two -sweat glands in the axilla branched or more branches 4. Compound -consist of a varying number of -mammary glands tubular simple tubular glands Saccular (alveolar) glands Types Characteristics Examples 1. Simple saccular -only one expanded bulb or Mucous and poison acinus at the end of the duct glands (amphibians) 2. Simple branched -with several acini arranged Meibomian glands along a single excretory duct -with single acinus divided by partitions into several smaller Sebaceous or oil glands acini 3. Compound -composed of several simple Mammary glands saccular saccular glands called lobules Sweat gland CLASSIFICATION OF EXOCRINE GLAND BASED ON SECRETION  TYPES OF GLANDS AS TO TYPE OF SECRETION MUCOUS GLANDS - secrete mucus (Ex. unicellular gland of aquatic vertebrates and some simple saccular glands of fishes and amphibians). SEROUS GLAND (sudoriferous glands) - secrete watery substance; (e.g. sweat glands) SEBACEOUS GLAND (oil glands) - Secrete oily substance (Ex. uropygial glands of birds, ceruminous glands and Meibomian glands of human),  SCALES EPIDERMAL SCALES Formed in the S. germinativum. Found in terrestrial tetrapods Shed and replaced from time to time (ecdysis). Ex. Scutes of turtles and snakes. DERMAL SCALES Derives from dermal bone. Dermatome origin  Ex. Fishes scales Types of Dermal Scales: Fishes Types Characteristics Hardening Image material 1. Cosmoid -small, thick scales -thick layer: -possessed only by Latimeria (lobe- cosmine finned fish) -thin layer: enamel 2. Placoid -consist of a basal plate embedded in -plate and spine: the dermis with a caudally directed dentine spine projecting to the epidermis -spine covering: -spine contains a central pulp cavity enamel for blood vessels, nerve endings, & lymph channels from the dermis 3. Rhomboid/ -rhomboidal in shape -surface of the Ganoid -composed of bones bone: ganoin 4. Ctenoid -bony layer is characterized by and Cycloid concentric ridges (growth increments) -anterior portion embedded in the dermis -allow increased flexibility of the body INTEGUMENT OF FISHES Skin of most fish is Non- keratinized and covered with mucus cuticle. Function includes: Prevent bacterial penetration. Contributes to the laminar flow of water across surface. Make fish slippery to predators. Includes chemicals that are repugnant or toxic to  enemies. EPIDERMIS OF FISHES Alive and active on the body surface No superficial layer of dead keratinized cells Mitosis is not restricted to the basal layer. Contains two types of cells; Epidermal cells – make up the stratified epidermis. Specialized unicellular glands –contributes to the mucus cuticle.  Placoid scale embedded in skin epidermis, Shark Chromatophores in epidermis and pulp (arrow)  Loading… E D Lamprey skin epidermis (E), thinner dermis (D) Unicellular glands (arrow). Guanophores – guanin (purine crystal); causes iridescence in fishes  INTEGUMENT OF AMPHIBIANS Specialized as a respiratory surface (cutaneous respiration). Epidermis is divided into four layers: S. basale, S. Spinosum, S. granulosum, S. corneum (allows cutaneous respiration). Dermis composed of fibrous connective tissue; S. spongiosum, S. compactum (mucus, poison gland, chromatophores are found in the dermis). INTEGUMENT OF REPTILES More adapted to terrestrial environment. Extensive keratinization. Fewer skin glands.  EPIDERMIS – epidermal scales are present (scutes), divided into three layers and these are; S. basale S. granulosum S. corneum DERMIS – composed of fibrous connective tissues, dermal bones are found in crocodiles, lizards, and extinct reptiles.  MOLTING / ECDYSIS The shedding of skin. Is usually periodic and complete in snakes and some lizards but often only partial in other species. Dependent upon the health of the snake, the ambient temperature, humidity and other environmental factors. Molting / Ecdysis – Shedding of cornified layer of skin. S. basale duplicates the deeper layers of granulosum and corneum forming new skin A temporary layer filled with WBC (stratum intermedium) is formed between the old and new skin WBC promote the separation and loss of the old superficial layer of the skin  SKIN GLANDS IN REPTILES Restricted to certain areas of the body. Important in reproductive behavior and protection. FEMORAL GLANDS – found along the underside of the hind limbs in the thigh region of lizards. SCENT GLANDS – open into the cloaca and on the margins of the lower jaw in crocodiles and some turtles. INTEGUMENT OF AVES Adapted to free movement over the muscles. Covered and protected by feathers.  EPIDERMIS – composed of S. basal and a transitional layer of S. corneum. DERMIS – rich supplied with blood, sensory nerves and smooth muscles. BROOD PATCH – highly vascularized dermis in the breast during brooding season.  SKIN GLANDS IN AVES UROPYGIAL GLANDS – secretes oil used for preening makes the feather water repellant. SALT GLANDS – excrete excess salt.  FEATHERS Are epidermal growths that form a distinctive outer covering, or plumage, on dinosaurs, both avian (bird) and some non-avian (non- bird) and possibly other archosauromorphs. Parts of a feather Types of feathers  Each feather grows from a structure in the bird's skin roughly comparable to a hair follicle in humans. First the old feather falls away. As a new one grows, it starts to look like a plastic drinking straw. Within this tube, or sheath, the feather itself develops, its barbs crammed in a tight packed spiral. After the tip of the spiral splits, allowing the feather to unfold, fan-like, into its final shape. INTEGUMENT OF MAMMALS HORN is a permanent pointed projection on the head of various animals that consists of a covering of keratin and other proteins surrounding a core of live bone. ANTLERS are a single structure composed of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels. HOOVES is the tip of a toe of an ungulate mammal, strengthened by a thick and horny keratin covering. ARTIODACT PERISSODACT