GENERAL ZOOLOGY MID-TERM REVIEWER*Integumentary System- Composed of skin.*Integument Skin- ( meaning to Cover) - The Largest organ of the body - Skin is made up of different tissues.*Stratified keratinized tissue- (stratified derived by the latin word Stratum/stratu meaning layer.) it is one of the tissue that you can found in the skin.*Keratinized- is the process to produced Keratinocytes.*Keratinocytes- produce keratin*Keratin- a fibrous protein. - It can only found in epidermis - WATERPROOF*Skin- the largest organ of the body it helps regulate body temperature, and permits the sensation of touch, heat and coldFunction of the Skin1. Protection- anatomical barrier from pathogens and damage.2. Sensation- Contain of variety of nerve endings.3. Thermoregulation- aids heat loss, reduce cutaneous blood flow and conserve heat.4. Storage and Synthesis- acts as a storage center for lipids and water. 2 Major layers of the skin 1. Epidermis- (came from the Greek word EPI meaning upon/over) is the outer layer of our skin it consist of a number of level, the deepest level of our Epidermis are extremely Active and Divide Constantly to make more & more new cells.Structure of epidermis > Epidermis is avascular, nourished almost exclusively by diffused oxygen from the surrounding air. > It is 95% keratinocytes. ( 5 Layers of the Epidermis ) 1. Stratum Corneum- Thickest of all the layers of Epidermis. And the outermost layer of epidermis - Composed of 20-30 all layers thick . - Accounts for about or 75% the thickness of your skin. - Cornified/horny cells completely filled with keratin - Consist of Dead skin (corneocytes) 2. Stratum Lucidum- ( Greek wordLucidus meaning Clear) - only found in thick skin. -Hairless - Contains Eleiden (Intermediate form or immature form of keratin) - it has a translucent appearance under the microscope. 3. Stratum Granulosum- (Granular Layer) compose of granules of fats/lipids. - 3-5 layers thick - dark staining granules called Keratohyalin (precursor of keratin)4. Stratum Spinosum- (Prickle Layer) - 8-10 layers of polyhedral cells that fit together. - Cells are covered with spine. - Spine join the cells together to strengthen the skin from the different factors of environment.5. Stratum Basal/Germinativum- (Basal Layer) - it is the deepest layer of the Epidermis that closest to the dermis. - Continuous layer of the cell. - generate/ proliferate through cell division. - stratum basal have 4 different kind of cells. > Keratinocytes- protein > Melanocytes- melanin > Langerhans- immune cells > Merkel- (Merkel-ranvier cell) Touch receptors*Merkel cell carcinoma- skin tumor.*Melanin- produce by melanocytes. It activate every time your exposed to sun. - produce brown pigment (TANNING PROCESS) - the concentrated melanin will become mole/freckles.*Nerve Ending- because of this you can feel different sensation to your body.6 Different Nerve Endings1. Free Nerve Endings- Pain2. Rufinnis Corpuscle- Heat/Warmth3. Krauses Corpuscle- Coldness4. Paccinian Corpuscle- Deep Pressure5. Meisners Corpuscle- Light touches6. Merkels Disc- Light TouchesDermis- The 2nd Layer of the skin. It consist of connective tissue and cushions the body from stress and strain. It is divided into 2 layers. The papillary and reticular Region.2 layers of Dermis1. Papillary Region- it is the uppermost layer of dermis. It intertwines with the rete ridges of epidermis. It is composed of fine and loosely arranged collagen fibers. It also consist of areolar tissue. - Vascular - free nerve endings pain - can found many capillary.2. Reticular Regions- is the lower layer of the dermis, it is located under the papillary dermis, it composed of dense irregular connective tissue featuring densely packed collagen fibers. It is the primary location of dermal elastic fibers. It contain most of the accessory structure. -All blood vessels can be seen. a. Phagocytes- A type of Leukocytes which undergo the process of Phagocytosis. b. Collagen- the skin Strength c. Elastin- Protein that gives the skin elasticity & flexible.*Tension lines/ lines of cleavage- -where surgeon use to make incisions because this is the area where wounds heal quickly.*LINEA ALBA- Cesarean cut. It have many collegen. *Dermal Papillae- (is came from the latin word Papula meaning pimple.)it is a small, nipple-like extension of the dermis into the epidermis.*Subcutaneous tissue/HYPODERMIS- (subcutaneous is the latin word Beneath the skin) it is the lowermost layer of the Integumentary system in vertebrates. It ued mainly for Fat/lipid storage.* Unicellular Glands- produce mucus. It made of only one Glandular Epithelium cell; called Intraepithelial Cells it consist only one cells.* Multicellular Glands- Goblets cells are the only human example. It consist more than one cell.Method of Secretion1. Merocrine/Eccrine Glands- it is a SUDORIFEROUS GLAND. it is the most abundant Glands of the body except : Genitalia and lips.2. Apocrine/Scent Gland- it is a SUDORIFEROUS GLAND. It releases Sweat with an odor.Example of Apocrine Sweat Glands. >Ceruminous Gland- Ear Sweat. It Produces Cerumen.>Mammary Gland- (Milk Gland) it only Active in Lactating Mother (OXYTOCIN- Love Hormone)>Circuminal Region- Present on Vaginal Orifice. Produce the natural Mucus of girls.>Axillary Gland- Natural sweat of armpit.3. Holocrine- (SEBACEOUS GLANDS) it is the most damaging type of secretion2 types of Skin Glands.> Sudoriferous Gland- (Sweat Glands) secrete sweat by the process of perspiration which regulates the body temperature.> Sebaceous Gland- (Oil Gland) lubricate and protect the skin by secreting sebum. It can found all over the body except in palms and soles.*Sebum- natural oil of the body. it is a mixture of oily substance and fragmented cells produce.Function of Sebum> Keeps the skin Moist.> Prevents the hair for becoming brittles.> Kills bacteriaSkin Disease due to the Infection of Sebaceous Gland,1. White Heads- Due to the blockage of sebum in the ducts of Sebaceous Gland.2. Black Heads- the blocked sebum undergoes the process of OXIDATION.3. Acne- Infection of oil Glands Accompanies of the Proliferation of pimples.3 colors of Skin Pigments. 1.Melanin- Brown Pigments. 2. Carotene- yellow orange Pigments 3. Cyanosis- Bluish Discoloration due to the decreased oxygen in the HEMOGLOBAR (Globular protein that makes the blood red) 2 types of membrane>Epithelial membrane- These membranes serve as linings and covering for various body structures, and they also form glands. > Cutaneous Membrane- The cutaneous membrane is the soft outer covering of vertebrates, and guards the underlying muscles, bones, ligaments, and internal organs.*Scales- is a small rigid plate that grows out of an animals skin to provide protection.Different types of fish scales: a. Cycloid Scales- they are CONCENTRIC RIDGES (Milkfish) appear to be the inner layer of ganoid or cosmoid. b. Ctenoid Scales- It has Spine. Have a toothed outer with tiny teeth called CTENII. The scales increases in size as the fish grow. c. Placoid Scales- Found in Cartilaginous Fishes (Sharks & rays) also called Dermal Denticles. Placoid scales do not grow in size but rather more scales are added as the fish increases size. It spines directed caudally. d. Cosmoid Scales- also called Armored fishes. Found in several ancient fishes or extinct fishes(Lobed-finned fishes SARCOPTERRGII) it also composed of a layer of dense lamellar bone called ISOPEDINE. e. Ganoid Scales- It is a diamond or rhomboid in shape. Found in sturgeons, paddle-fishes, gars bowfin and bichirs. Derived from cosmoid scales.SKIN OF JAWLESS FISHES - they have relatively thick skin. - of the several types of epidermal glandular cells, one secretes the protective cuticle. - Multicellular Slime glands secrete large amount of mucous to cover the body surface for protection.SKIN OF CATILAGINOUS FISHES - Multilayered and contains mucus and sensory cells. - the dermis contains bones in form of placoid scales called denticles. - denticles contain blood vessels and is very familiar to vertebrate teeth.SKIN OF BONY FISHES - They contain Scales. - A thin layer of dermal tissue overlaid the superficial epidermis normally covers the scales. - their skin are permeable and can be used in gas exchange. - they grow at the margins and over the lower surface.*BIRDS- integumentary system consist of the skin, the feathers and the appendages (Claws and beak)The Fowls Skin is divided into a number of Separate areas. > The feathered skin > The scale covered skin on the lower legs and feet. > The hard, horny areas of the beak and toenails. > The pad of the foot (or Plantar) > the skin of the comb and wattles*Pterylae- the areas where feathers are grow.*Apteria- the areas where feathers do not grow.Structure of a Cross-section bird skin- the skin is composed in the main 2 different tissues.-Connective tissue of the dermis and hypodermis where the cells are widely spaced.- Cellular outer layer of the skin and forms the feather. a. Epidermis- connect with air sacs of the respiratory system thus enhancing the ability to fly. Different skin types contain different amounts and distribution of special compounds mainly Collagen, elastin and keratin. > The flattened, horny cell layer- the outermost layer. > the transitional layer- Joins the outer layer to the inner layer. It is here that the cells formed in the third innermost layer are transformed into the hard, horny type found in the outermost layer. > The columnar Cell layer- this is the innermost layer of the epidermis and is the germinative layer where the cells of the epidermis are formed. b. Dermis- it is relatively thin and shows a uniform, microscopic structure. The main component of the dermis is collagen with a small amount of elastin.*Hypodermis- contains fewer cells and is more loosely arranged than the dermis. Fat is stored here in special adipose cell(Adipose tissue is fat tissue)*Feathers- the lightness and stiffness of keratin is also a key to bird flight.it provides the large airfoils necessary for flapping and gliding flight. In another form the light fluffy down feathers also made of keratin, are some of the best natural insulator.1. Contour feathers- are large feathers that cover the body, wing and tail. They have an expanded vane that provides the smooth, continuous surface that is required for effective flight.2. Down feathers- are the only feather covering a chick and form the main insulation layer under the contour feathers of the adult. They have no shaft but consist of a spray of simple, slender branches.3. Pin or filoplumes feather- pin feathers have a slender hair-like shaft often with tiny tuft of barbs on the end.4. Plumules- found beneath the contour feathers where they form a soft, downy undercoat. They have a short shaft with radiating, free barbs and barbules. They play large part in trapping the air and holding it still-thus improving their ability to conserve warmth.5. Bristles- are found around the mouth and eyes of chickens and are thought to be primarily used to aid the sensory ability of birds and protect sensitive ares.*Reptiles- their skin reflects their greater commitment to terrestrial existence. -Reptile skin has two principal layers: The Dermis, which is the deeper layer of connective tissue with a rich supply of blood vessels and nerves. And the Epidermis which in reptiles consist of up to seven sub-layers or strata of closely packed cells, forming the bodys outer protective coating. - dermis is provided with Chromatophores, color bearing cells that give many lizards and snakes their colorful hues - the characteristic Scales of reptiles are formed largely of Keratin.7 epidermal layers of a reptiles1. The stratum germinativum- the deepest layer of living cells which have the capacity for rapid cell division.2-3. The Clear layer and Lacunar Layer- which mature in the old skin layer as the new skin in growing beneath4-6. The