Integumentary System Of Mammals PDF

INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 1 INTEGUMENTARY SYSTEM OF MAMMALS ZOO 101 : ALAFIA, A.O. (PH.D) 2024/2025 SESSION  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 2 THE MAMMALIAN BODY The structure of a mammal is made up of different body parts, each with a unique fu...

INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 1 INTEGUMENTARY SYSTEM OF MAMMALS ZOO 101 : ALAFIA, A.O. (PH.D) 2024/2025 SESSION  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 2 THE MAMMALIAN BODY The structure of a mammal is made up of different body parts, each with a unique function. These body parts are critical to their sustenance and adaptation to their immediate environment, and include the hair, skin, skeletal system, teeth, heart, kidneys, and brain. Mammals are vertebrates that possess hair and mammary glands. Several other characteristics are distinctive to mammals, including certain features of the jaw, skeleton, integument, and internal anatomy. Modern mammals belong to three clades: monotremes, marsupials, and eutherians (or placental mammals).  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 3 CHARACTERISTICS OF MAMMALS The presence of hair is one of the most obvious signs of a mammal. Although it is not very extensive on certain species, such as whales, hair has many important functions for mammals. Mammals are endothermic, and hair provides insulation to retain heat generated by metabolic work. Hair traps a layer of air close to the body, retaining heat. Along with insulation, hair can serve as a sensory mechanism via specialized hairs called vibrissae, better known as whiskers. These attach to nerves that transmit information about sensation, which is particularly useful to nocturnal or burrowing mammals. Hair can also provide protective coloration or be part of social signaling, such as when an animal’s hair stands “on end.”  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 4 INTEGUMENTARY SYSTEM OF MAMMALS The integumentary system of vertebrates comprises skin, scales, feathers, hair and glands. In mammals,  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 5 INTEGUMENTARY SYSTEM Vertebrate integument also called the skin It covers most of the outer layer of the body The skin is the Largest organ in the mammalian body, is formed during embryonic development, Grows with the animal Multilayered into epidermis, dermis and hypodermis It consist of skin, and other appendages such as hair, nails and glands  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 6 A section of the mammalian skin  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 7 GENERAL FEATURES OF INTEGUMENT Appendages of the skin includes glands, hair and nails The epidermis produces hair, feathers, baleen, claws, horns, beak and some types of scales The dermis gives rise to dermal bones and osteoderms of reptiles Skin contains nerves and blood vessels are usually located in the dermal layer of the skin  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 8 Epidermis: outer layer of epithelial tissue and is several cells thick. Dermis: connective tissue beneath the epidermis and is made up of collagenous, reticular, and elastic fibers. Hypodermis: below the skin and separates the skin from deeper tissues, loose connective tissue, adipose tissue, and nerve endings.  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 9 SKIN THICKNESS Thickness vary with body region, the thickest is about 4mm. Skin is characterized as thin or thick skin based on the thickness of the epidermis and dermis Some part are hairless: palm and Sole  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 10 LAYERS OF THE SKIN the skin is made up of three layers Epidermis, dermis and Subcutaneous Hypodermis  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 11 EPIDERMIS Is the outerlayer of the skin, It is ectodermal in origin Keratizined stratifies squamous epithelium Lacks vessels Contains sparse nerve endings for receiving stimuli such as touch and pain  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 12 DERMIS The dermal layer is found below the epidermis It is a thick layer of connective tissue to which the epidermis is attached. Its deepest part continues into the subcutaneous tissue without a sharply defined boundary. Its thickness is for this reason difficult to determine but 0.2mm - 4mm is a good estimate for "average" skin. Unlike the epidermis, the dermis is richly supplied with blood vessels and nerves for sensation of touch, pressure, temperature and pain The dermis may be divided into two sublayers : PAPILLARY AND RETICULAR  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 13 HYPODERMIS A major function of the subcutaneous tissue is to connect the skin to underlying tissues such as muscles 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. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 95% of body fat). Fat serves as p  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 14 FUNCTIONS OF THE SKIN The skin functions in thermoregulation, Protection :physical barrier for protection of internal organs against negative effects of heat, sun , cold and prevent many foreign substance metabolic functions and Sensation Nutrition Immunity Wound healing Absorption Excretion  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 15 FUNCTIONS OF THE SKIN The skin’s role in the production of Vitamin D Vitamin D is produced when sunlight hits the skin By absorbing ultraviolet rays from the Sun, the Skins 7-dehydrocholesterol (provitamin D3) photolyzes it to previtamin D3, which undergoes a rapid transformation to vitamin D3(cholecalciferol). Once vitamin D3 is formed in the skin, it diffuses into the blood vessels of the dermis, the layer of skin beneath the epidermis. From there, it enters the bloodstream and is transported to various tissues and organs in the body.  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 16 CELLS OF THE SKIN Keratinocytes Melanocytes Langerhan’s Merkel’s cells  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 17 CELLS OF THE SKIN Keratinocytes – most predominant originate in the basal layer, responsible for the formation of the epidermal water barrier by secreting lipids. They regulate calcium absorption by the activation of cholesterol precursors Melanocytes Produces MELANIN, which is responsible for pigmentation of the skin  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 18 CELLS OF THE SKIN Melanocytes Melanin absorbs some of the potentially dangerous radiation in sunlight. It also contains DNA repair enzymes which reverse UV damage, and people who lack the genes for these enzymes suffer high rates of skin cancer. One form predominantly produced by UV light, malignant melanoma, is particularly invasive, causing it to spread quickly, and can often be deadly. A disease that causes the loss of skin colour in blotches. Vitiligo occurs when pigment-producing cells die or stop functioning, The condition occurs when your body’s immune system destroys melanocytes..  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 19 Cells OF THE SKIN Langerhans Cells Also known as dendritic cells First line of defense for the skin Play a role in antigen presentation Found in the stratum spinosum Take up antigens in skin and transport to the lymph node Merkel cells Found in stratum basal Serve sensory functions as mechanoreceptors for light, touch and most populous in fingertips  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 20 APPENDAGES OF THE SKIN HAIR, NAILS, AND GLANDS NAILS In rats they are known as CLAWS Claws are used for scratching, digging HAIR Rats have fur while humans have vellus hair More on the body than on the ears and tail Lanugo is slightly thicker (and more fur-like) than vellus hair  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 21 FUNCTIONS OF HAIR protection against external factors; vibrissae and guard hairs which guard the nostrils producing sebum, apocrine sweat and pheromones; impact on social and sexual interactions; (Non verbal cues), Pubic hair signifies maturity and traps sexual scents, sexual recognition thermoregulation and being a resource for stem cells, insulating the skin, camouflage, Hair on the scalp provides insulation from cold for the head. The hair of eyelashes and eyebrows helps keep dust and perspiration out of the eyes, and the hair in our nostrils helps keep dust out of the nasal cavities.  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 22 GLANDS OF THE SKIN Mammalian integument, or skin, includes secretory glands with various functions. A gland is an organ that make one or more substances e.g hormones, sweat Sudoriferous (Sweat gland produces sweat and genital secretion , Ceruminous: produces ear wax; Ceruminous glands are found within the human, but not rodent, external ear canal and are responsible for wax secretion. Sebaceous glands produce a lipid mixture called sebum that is secreted onto the hair and skin for water resistance and lubrication. Sebaceous glands are located over most of the body.  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 23 SWEAT GLAND Eccrine glands found all over the human body, they produce sweat, or perspiration, which is mainly composed of water. In most mammals, eccrine glands are limited to certain areas of the body, and some mammals do not possess them at all. However, in primates, especially humans, sweat figures prominently in thermoregulation, regulating the body through evaporative cooling. Sweat glands are located over most of the body surface in primates. Apocrine glands, or scent glands, open into your hair follicles secrete substances that are used for chemical communication, such as in skunks. Occur over most of the body only in Mammals Rodents do not have sweat glands. Cats and dogs have sweat glands in the pads of their feet  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 24 SWEAT GLANDS Eccrine sweat glands allow for temperature control. When body temperature rises during physical activity, increased ambient temperature, or fever, these glands respond by secreting sweat. This sweat is eventually evaporated from the surface of the skin, effectively cooling down body temperature. The initial sweat released by eccrine glands is made up of water as well as sodium and potassium ions; however, the epithelial lining of the ducts reabsorbs a majority of these ions, resulting in a larger water composition of sweat.  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 25 SWEAT GLANDS Apocrine sweat glands present at birth do not become active until puberty. In some mammals, these glands act as the main thermoregulator; however, their function is unknown in humans. Some hypothesize that apocrine glands are responsible for body odor or pheromone production. While the initial secretion of apocrine glands is milky and odorless, bacteria on the skin surface eventually break down the fluid, releasing a distinctive odor  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 26 SEBACEOUS GLAND: produces an oily substance called sebum Sebum lubricates the skin to protect against friction The sebaceous gland empties into the hair follicles It possess an innate antibacterial activity and anti-inflammatory functions  INTEGUMENTARY SYSTEM - DR. ALAFIA, A.O. 27 MAMMARY GLAND Mammary glands produce milk that is used to feed newborns. While male monotremes and eutherians possess mammary glands, male marsupials do not. Mammary glands likely are modified sebaceous or eccrine glands, but their evolutionary origin is not entirely clear Milk producing gland that develop only during pregnancy and lactation Rich secretion released through ducts opening at the nipples or teat Six pairs of mammary glands in rats