A&P EXAM 1 STUDY GUIDE.pdf

CHAPTER 1 Terms Anatomy is the study of structure and form - ex. components of blood vessels Physiology is the study of function of the body parts - ex. How blood vessels work Cytology - cellular anatomy, study of cells and their structures Histology - study of body tissues...

CHAPTER 1 Terms Anatomy is the study of structure and form - ex. components of blood vessels Physiology is the study of function of the body parts - ex. How blood vessels work Cytology - cellular anatomy, study of cells and their structures Histology - study of body tissues Gross anatomy - macroscopic anatomy - studies structures that are visible to naked eye such as brain. Systemic anatomy - studies the anatomy of each functional system, ex. Urinary system includes kidneys, ureters, urethra, urinary bladder. Regional anatomy - examines all the structures in a region of the body as a complete unity. Ex. Study the axillary/armpit region includes the blood vessels, nerves lymph nodes, tissues, skin, etc. Surface anatomy - focuses on superficial anatomic markings and the internal body structures that relate to the skin covering them. Important for things like pulse locations/cpr location. Comparative anatomy - examines similarities and differences in the anatomy of different species. Ex. Limb structures in humans, chimps, etc. Embryology - concerned with developmental changes from conception to birth Pathologic anatomy - all anatomic changes resulting from disease Radiographic anatomy - relationships among internal structures that may be visualized by scanning procedures like x-rays. PROPERTIES OF ORGANISMS Organization - complex structure/order Metabolism - includes anabolism and catabolism, small molecules join together, catabolism large molecules broken down Growth/development Responsiveness - detect/react to stimuli Regulation - adjust internal bodily function in response to environmental changes Reproduction - produce new cells for growth, maintenance, repair SIMPLE TO COMPLEX ORGANIZATION Chemical level - atoms and molecules, macromolecules like DNA. Macromolecules form organelles. Cellular level – cells Tissue level - tissues (groups similar cells that perform common functions. 4 types including o epithelial (covers exposed surfaces and lines body cavities) o Connective (protects, supports and binds structures/organs) o Muscle (produces movement) o Nervous (conducts nerve impulses for communication) Organ level - composed of organs. Organs contains 2 or more tissue types that work together to perform specific and complex functions. Ex. Small intestine Organ system level - contains multiple related organs that work together to coordinate activities and achieve a common function. Ex. Digestive system including stomach, small/large intestine, liver. Organismal level - highest level of structural organization. All body systems function interdependently in an organism. SYSTEMS All organisms exchange nutrients, wastes, and gases with their environment. Integumentary system - provides protection, prevents water loss and gain, synthesizes vitamin D, releases secretions, regulates body temp, and houses sensory receptors Muscular system - produces body movement, generates heat when muscles contract Skeletal system - provides support and protection, site of hematopoiesis, stores calcium and phosphorus, provides cities for ligament and muscle attachments. Nervous system - a regulatory system that responds to sensory stimuli, and controls muscles and some glands. Also responsible for consciousness, intelligence and memory. Endocrine system - consists of glands and cell clusters that secrete hormones, maintain homeostasis of blood composition and volume, control digestive processes, and control reproductive functions Cardiovascular system - consists of heart and blood vessels, helps distribute hormones, nutrients, gases, and pick p wastes. Lymphatic system - transports/filters lymph, may participate in an immune response Respiratory system - responsible for exchange of gases between blood and and air in the lungs  Urinary system - filters the blood to remove waste, concentrates waste in urine and expels urine Digestive system - mechanically/chemically digest food, aborbs nutrients and expels waste Male reproductive system - produces male sex cells and hormones Female reproductive system - produces female sex cells and hormones. Site of growth and development of embryo and fetus. Produces and secretes breast milk for nourishment of newborn. Anatomic position - feet flat to ground, standing upright, feet parallel, upper limbs at sides of body, palms face anteriorly, head is level, eyes look forward Section - cut or slice Plane - imaginary flat surface passing through the body Coronal plane/frontal plane - vertical plane that divides the body/organ into anterior and posterior parts Transverse - horizontal plane , divides the body or organ into superior and inferior parts midsagittal plane - median plane, vertical plane and divides the body/organ into equal left and right halves. Oblique planes - pass through a structure at an angle Ventral cavity - do not completely encase their organs in bone. The thoracic diaphragm separates the thoracic cavity and the abdominopelvic cavity. Posterior aspect - contains cavities that are completely encased in bone  Posterior aspect - contains cranial cavity and vertebral canal. Contains brain and spinal cord. Serous membranes have two layers Parietal layer - typically lines the internal surface of the body wall Visceral layer - covers the external surface of organs. Serous cavity - sits between the parietal and visceral serous membrane layers. Serous membranes secrete serous fluids which acts as a lubricant. Friction between organs is reduced by serous fluid. Thoracic cavity - space between lungs is calls the mediastinum, and contains the heart, thymus, esophagus trachea, and major blood vessels. Heart is enclosed by a 2 layer serous membrane called serous pericardium. Parietal pericardium is the outer layer Visceral pericardium covers the heart’s external surface Lungs are surrounded by 2 layer membrane called the pleura. Includes parietal pleura and visceral pleura. Abdominopelvic cavity - contain abdominal cavity and pelvic cavity. Abdominal cavity is superior and sits on top of hip bone. Contains pelvic cavity. Peritoneum - serous membrane associated with abdominopelvic cavity. Contains parietal and visceral peritoneum. Contains peritoneal cavity. 9 regions - see book for picture. Right hypochondriac, epigastric, left hypochondriac Right lumbar, umbilical, left lumbar Right iliac, hypogastric, left iliac Quadrants (same concept) HOMEOSTASIS Homeostasis - regulates temperature, heart rate, blood pressure, blood sugar, blood oxygen 3 components of homeostasis Receptor - body structure that detects stimulus Control center - structure (usually brain or gland) that integrates input and initiates change Effector - structure (muscle or gland) that brings about a change Feedback loops include o Stimulus o Receptor o Control centern o Effectors o Homeostasis restored 2 types of feedback - positive and negative Most processes are negative feedback in which the resulting action happens in the opposite direction of the stimulus. Ex. If stimulus increases, homeostatic system causes a decrease in the stimulus until it returns to the set point. If the stimulus decreases, the homeostatic system causes an increase in the stimulus until it returns to normal. Homeostatic regulation through nervous system - includes withdrawal reflex, regulating heart rate and blood pressure, changing breathing rate. Positive feedback loops are infrequent. It includes breastfeeding and childbirth. Diabetes is an example of homeostatic imbalance. PANCREAS SITS BEHIND STOMACH IN ANTERIOR VIEW CHAPTER 5 Tissues are groups of similar cells and extracellular material that perform a common function, such as providing protection or facilitating body movement Histology - the study of tissues, uses microscopy 4 types of tissues - muscle, connective, nervous, epithealial Acronym CONMEN (con, mus, epi, nerv) They vary based on the structure, function and composition of the extracellular matrix Extracellular matrix includes protein fibers, water, dissolved molecules, and can range from fluid to semisolid to sold. EPITHELIAL CELLS composed of 1 or more layers of closely packed cells, contains little to no extracellular matrix between the cells. Covers body surfaces, lines the body cavities and organ cavities, and forms glands Characteristics include Cellularity - tightly packed cells, little extracellular matrix between cells Polarity - apical surface exposed to the external environment or internal body space. May have cilia or microvilli (cilia help move fluid/stuff, microvilli increase surface area for secretion/absorption) Lateral surfaces may contain junctions. Basal surface attaches epithelial cell to underlying connective tissue. They act like glue. They are composed of collagen, glycoproteins, and proteoglycans. Avascularity - lack of blood vessels. Nutrients relies on apical surface or diffusion from blood vessels below basal surface. Innervation - supplied with a lot of nerves to detect changes in environment High regeneration - necessary when exposed to environment, abrasion, and damage Functions of epithelial tissue Protection - from external and internal surfaces, dehydration, abrasion, and destruction from physical, chemical and biological agents Selective permeability - “gatekeepers” Secretions - some epithelial cells form glands, can be individually scattered (ex. Goblet cells) or in clusters. Sensations - epithelial tissue are innervated, concern touch, pressure, temperature, and pain Classification of Epithelial cells First part of name is from number of epithelial cell layers (simple, or stratified) Simple epithelium - 1 layer, usually found were stress is minimal and filtration, absorption or secretion is primary function Second part describes shape of cells at apical surface Stratified epithelium - 2 or more layers of epithelial cells. Cells in the basal layer continuously regenerate as the cells in the apical layer are lost due to abrasion or stress. Pseudo stratified epithelium - layers appear stratified because the nuclei are distributed at different levels. Transitional cells can readily change their shape depending upon the degree to which the epithelium is stretched, ex. Bladder.  SIMPLE SQUAMOUS - AIR SACS IN LUNGS, LUMEN OF BLOOD VESSELS, SEROUS MEMBRANES SIMPLE CUBOIDAL - KIDNEY, THYROID, MOST EXOCRINE GLANDS NONCILIATED SIMPLE COLUMNAR - GASTROINTESTINAL TRACT CILIATED SIMPLE COLUMNAR - BRONCHIOLES, UTERINE TUBES CILIATED PSEUDOSTRATIFIED - RESPIRATORY TRACT (PHARYNX, TRACHEA, BRONCHI) NONCILIATED PSEUDOSTRATIFIED COLUMNAR - MALE URETHRA Endothelium - name used for simple squamous epithelium that lines both blood vessels and lymph vessels. Mesothelium - name given to the simple squamous epithelium that forms the serous membranes of body cavities. KERATINIZED STRATIFIED SQUAMOUS – EPIDERMIS NONKERATINIZED STRATIFIED SQUAMOUS - ORAL CAVITY, PHARYNX, LARYNX, ESOPHAGUS, LINING OF VAGINA AND ANUS STRATIFIED CUBOIDAL - DUCTS OF EXOCRINE GLANDS AND OVARIAN FOLLICLES  STRATIFIED COLUMNAR - SALIVARY GLANDS, EYE, URETHRA TRANSITIONAL - URINARY BLADDER GLANDS Individual cells or multicellular organs mostly composed of epithelial tissue. Secrete substances. May crude mucus, ions, hormones, enzymes, urea, etc. Endocrine glands - lack ducks and secrete hormones into bloodstream. Include thyroid and adrenal glands. Exocrine glands - deeper into underlying connective tissue, connected to surface of epithelial tissue through a duct. Includes sweat glands, mammary glands, and salivary glands. Exocrine glands can also be unicellular, in which case it will be located closer to the surface (goblet cell) Multicellular exocrine glands often have acini (clusters of cells that produce the secretion) You can also find exocrine glands in the intestines to digest food Mecrocine glands include lacrimal (tear glands), salivary glands, sweat glands. Secretion through exocytosis. Apocrine glands - also includes cerunmious glands. They produce their secretory material when the apical portion pinches off.  Holocrine glands - formed when cells accumulate a product; then the cell disintegrates. The sebaceous glands in the skin are an example of holocrine glands. Hair and ears. CONNECTIVE TISSUE Most diverse, abundant and widely distributed of the tissues. Support, protect and bind organs. Includes tendons, ligaments, adipose tissue, cartilage, bone, and blood All derived from mesenchyme Range of vascularity (high to none) Range of regenerative capacity (Bone and blood are high, cartilage is not) Characteristics Includes cells, protein fibers, and ground substances. Ground substances and protein fibers form the extracellular matrix. Resident cells - stationary cells that are permanently housed within the connective tissue they support, maintain and repair the extracellular matrix. They include o Fibroblasts - most abundant resident cells. Produce fibers and ground substance components of the extracellular matrix o Adipocytes - fat cells, small clusters, o Mesenchymal - type of embryonic stem cell, helps replace cells o Fixed macrophages - derided from a type of leukocyte. Dispersed throughout the matrix and engulf damaged cells and pathogens. Also releases chemicals Wandering cells - continuously move throughout the connective tissue proper and are components of the immune system. They also may help repair damaged extracellular matrix. Primarily leukocytes. Protein fibers - usually strengthen and support the tissue. Includes collagen fibers, reticular fibers, and elastic fibers. Collagen fibers - long protein fibers that are strong, flexible and resistant to stretching. About 25% of body’s protein. Appear white in fresh tissue. Major component of tendons and ligaments Reticular fibers - such thinner than collagen fibers. Same units as collagen but different structure. Abundant in the stroma of organs such as lymph nodes, spleen and liver. Tough and flexible Elastic fibers - contain protein elastin. Stretch and recoil easily. Often called yellow fibers. Abundant in skin, arteries and lung. Allows them to return to their original shape after being stretched. Ground substance Molecular material produced by connective tissue cells. This is were connective tissue cells and protein fibers reside. May be viscous (blood), semisolid (cartilage), or solid (bone). Ground substance and protein fibers form extracellular matrix Contains glycosaminoglycans (GAGs). They attract and absorb water. It is a polysaccharide with an attached amine group Proteoglycan - GAG linked to a protein. Glycoproteins - (protein with carbohydrate attached), acts as glue to bond connective tissue cells and fibers to ground substance. Functions of connective tissue Include physical protection, support and structural framework Binding of structures Storage Transport Immune protection Embryonic Connective Tissue 2 types, mesenchyme and mucous connective tissue Contain stellate (star shaped) or spindle shaped mesenchymal cells Mesenchyme - first type of connective tissue to emerge in the developing embryo Mesenchyme is the tissue from which all other connective tissues are formed. They act as stems cells to provide support in the repair of tissue following damage or injury Mucous connective tissue (Wharton’s jelly) - located within the umbilical cord only Mesenchyme begins to differentiate in the developing fetus into the connective tissues found in the adult body. Three types of Connective tissue after birth Connective tissue proper Supporting connective tissue Fluid connective tissue  Loose connective tissue - fewer cells and protein, irregularly arranged, abundant ground substance, supports structures and organs, highly vascularized. Includes o Areolar connective tissue - PAPILLARY LAYER OF DERMIS, SUBCUTANEOUS LAYER, ORGANS, NERVES o adipose connective tissue - SUBCUTANEOUS LAYER, 2 TYPES ▪ Brown found in newborns, generates heat ▪ White, - for long term energy storage, insulating and cushion o Reticular connective tissue - SPLEEN, LYMPH, BBONE MARROW Dense connective tissue - composed of primarily protein fibers, has less ground substance. Collagen fibers are usually the dominant fiber type. o DENSE REGULAR - TENDONS AND LIGAMENTS o DENSE IRREGULAR - RETICULAR LAYER OF DERMIS, PERICHONDRIUM o ELASTIC - WALLS OF ARTERIES, TRACHEA, VOCAL CORDS Supportive connective tissue - Strong and durable framework that protects/supports tissues. Has semisolid and solid ground substances. 2 types o Cartilage - also called chondrocytes. Strong and resilient and flexible. Can withstand deformation. (Nose and ears) ▪ Hyaline cartilage - TIP OF NOSE, BRONCHI, LARYNX, ENDS OF LONG BONES, FETAL SKELETON ▪ Fibrocartilage - INTERVETERBRAL DISCS, MENISCI OF KNEE JOINES ▪ Elastic cartilage - EXTERNAL EAR, EPIGLOTTIS  o Bone - Also known as osseous connective tissue. More solid and provides greater support. Not as flexible. Extensively vascularized ▪ Mature bone cells are called osteocytes. they are housed in spaced in the extracellular matrix called lacunae o 2 forms ▪ compact bone - has neuromuscular canals and a uniform pattern. Forms osteons which display rings called lamellae. ▪ spongy bone - located within the interior of a bone. Strong and lightweight. o Provide support and serve as levers for skeletal muscle movement. Support soft tissues and protect body organs. The hard extracellular matrix of bone stores minerals. Some spongy bone houses hematopoietic cells, which form a type of reticular connective tissue that makes blood cells Fluid Connective Tissue 2 types o Blood - composed of formed elements, including cells, erythrocytes and leukocytes, and platelets o Liquid ground substance is plasma and it contains proteins and solutes Blood - erythrocytes transport respiratory gases, leukocytes protect body from infection. Platelets and protein fibers help form clots Plasma transports nutrients, wastes and hormones Lymph is derived from blood plasma, but contains no cellular components. Muscle Tissue Is contractile, conductive, elastic, extensible, and excitable. Produces movement. Well vascularized Includes 3 types o Skeletal muscle (striated/voluntary muscle tissue) - responsible for movement of the skeleton, thermoregulation. Composed of skeletal muscle fibers o Cardiac muscle - confined to the myocardium. Involuntarily contracts with pacemaker cells. o Smooth muscle - found in the walls of most viscera (internal organs), such as intestines, stomach, airways, bladder, uterus, blood vessels. Nervous Tissue Located within the brain, spinal cord, and nerves that traverse through the body. Consists of neurons - they receive, process and transmit nerve impulses Contains glial cells - responsible for protection, nourishment and support of the neurons Neurons contain a cell body that houses the nucleus and organelles. The branches are called nerve cell processes Dendrites - receive incoming signals and transmit the information to the cell body Axon - carries outgoing signals to other cells Nerves cells are long, some are longer than 1 meter ORGANS A structure composed of 2 or more tissue types that work together to perform specific, complex functions. The stomach contains all four types of tissue Body membranes are formed from an epithelial layer that is bound to an underlying connective tissue. These membranes line body cavities or a joint surface, cover the viscera, or cover the body’s external surface. There are four types of body membranes: mucous, serous, cutaneous, and synovial, shown in A mucous membrane, also called a mucosa lines passageways and compartments that eventually open to the external environment; A serous membrane lines body cavities (see section 1.5e) that typically do not open to the external environment and covers the external surface of many organs Serous membranes produce a thin, watery serous fluid. They have 2 layers, the parietal layer and visceral layer. Between them is the serous cavity. Largest membrane is the cutaneous membrane (skin) - composed of keratinized stratified squamous epithelium (epidermis) Some joints in the body are lined by a synovial membrane. within this membrane secrete a synovial fluid that reduces friction among the moving bone parts and distributes nutrients to the cartilage on the articular surfaces of bone. CHAPTER 6 Integument - body’s largest organ o Surface is epithelium and protects underlying layers o Connective tissue is below and provides strength/resilience ^also contains smooth muscle associated with hair follicles (arrestor pili) Nervous tissue - detects and monitors sensory stimuli for information about touch, pressure, temperature and pain ~7& body weight 2 distinct layers o Epidermis - stratified squamous epithelium o Dermis - deeper layer of areolar and dense irregular o Subcutaneous/hypodermis - areolar and adipose connective tissue EPIDERMIS Keratinized, stratified squamous epithelium 0.075mm to 0.6mm thick Several layers o Stratum basale o Stratum spinous  o Stratum granulosum o Stratum lucidum (found in thick skin only) o Stratum corneum Stratum Basale Deepest epidermal layer Single layer of cuboidal or low columnar cells attached by hemidesmosomes to basement membrane ( separates epidermis from connective tissue of dermis) 3 cell types in stratum basale o Keratinocytes ▪ most abundant cell type ▪ Found throughout epidermal strata ▪ Dominated by keratinocyte stem cells (makes more keratinocytes) o Melanocytes ▪ long branching processes and scattered among keratinocytes ▪ Produce and store pigment melanin in response to UV exposure ▪ Uses melanosomes to transfer melanin pigment ▪ It surrounds the nucleus of the keratinocyte and shields the DNA from UV radiation o Tactile cells ▪ Few in number and scattered around the stratum basale ▪ Sense to touch and release chemicals that stimulate sensory nerve endings when compresses ▪ Common in sensitive areas such as fingertips Stratum Spinosum Formed by several layers of polygonal keratinocytes Formed when the keratinocyte stem cell divides and new cell is pushed up to the stratum spinosum Keratinocytes attaché to their neighbors by membrane junctions called desmosomes (helps provide support) Look like porcupines under microscope Also contains epidermal dendritic cells o Immune cells that help fight infections in epidermis (pathogens as well as cancer) Stratum Granulosum Consists of 3 to 5 layers of keratinocytes superficial to the stratum spinous Site where keratinization occurs (keratinocytes produce keratin). Causes nucleus and organ less of cells to disintegrate and die Keratinization not complete until keratinocytes reach the superficial epidermal layers Stratum Lucidum Clear layer, thin and translucent About 2 to 3 keratinocyte layers Found only in thick skin within palms and soles Filled with eleidin (product of keratin formation) Helps protect skin from UV light Stratum Corneum Most superficial layer of epidermis. Consists about 20 - 30 layers of dead keratinized cells that are anucleate (no nucleus) What remains of the cells in the corner is essentially keratin protein enclosed in a thickened plasma membrane (formed from lipids which helps form water barrier) Cells take 2 weeks to move through the layers to the corner, stay about 2 weeks in the corner, and then are shed. The thickened surface of the corneum along with some exocrine gland secretions (sweat ) make it unsuitable for microbial growth THICK AND THIN SKIN Thick skin o Found on the palms and soles of feet and contain all 5 strata o 0.4mm - 0.6mm thick o Houses sweat glands but no hair follicles or sebaceous glands Thin Skin o Covers most of the body o Lacks stratum lucidum o Contains hair follicles, sebaceous glands, and sweat glands o 0.075mm to 0.150mm thick SKIN COLOR Results from a combination of colors from hemoglobin, melanin and carotin Hemoglobin - oxygen binding protein in erythocytes, bright red color, blood vessels in dermis, increase in color tone during vasodilation Melanin -produced and stored in melanocytes o 2 types - eumalinin and pheomelanin ▪ Eumalinin - produces shades of brown and black ▪ Pheomlanin - prouduces tan, yellow and red Melanin is transferred in melanosomes from melanocytes to keratinocytes in stratum basale Appearance of skin is due to heredity and exposure to UV light All people have about the same number of melanocytes Melanocyte activity varies among people and ethnicities Darker individuals have melanocytes that produce relatively more and darker melanin Carotene - yellow orange pigment acquired from yellow orange vegetables like carrots, corn, squashes. o Stored inside keratinocytes of the stratum corneum and subcutaneous fat o Most common form is beta-carotene, primary source of vitamin A, plays a role in vision, reduce free radicals and improve immune function Albinism - inherited recessive condition, enzyme needed to produce melanin (tyrosinase) is nonfunctional. Typically presents as white hair, pale skin and pink irises  Skin Markings o a nevus (mole) is a harmless localized growth of melanocytes. May become malignant (called malignant melanomas). Exposure to UV light may increase risk o Freckles - yellow or brown spots. Increase in melanocyte activity but not numbers Hemangioma - Anomaly that results in skin discoloration due to blood vessels that proliferate to form a benign tumor Capillary hemangiomas - appear in skin as bright red to purple nodules present at birth and disappear soon after, but could develop in adults Cavernous hemangiomas - involve large dermal blood vessels and may last for life Friction ridges - found on palms, fingers, soles and toes. o Formed from folds and valleys of dermis/epidermis. o Increase friction contact o Unique tool for identification o Dermatoglyphics - study of friction ridge patterns DERMIS Deep to epidermis 0.5mm to 3mm thick Composed of connective tissue proper, primarily collagen fibers as well as elastic and reticular fibers Dendritic cells (immune function) Blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings, smooth muscle tissue (arrestor pili) 2 layers o Superficial papillary layer o Deeper reticular layer Papillary layer of the Dermis Superficial part of the dermis, deep to the epidermis Composed of areolar connective tissue Contains dermal papillae that work with epidermal ridges to interlock the epidermis and papillary layer of dermis The dermal papilla contain capillaries that supply nutrients to the cells of the epidermis Dermal papilla contain sensory nerve endings that act as tactile receptors to monitor touch on the epidermis Reticular layer of dermis Deeper, major portion of the dermis Extends from papillary layer to underlying subcutaneous layer Consists primarily of dense irregular connective tissue Contains bundles of collagen that surrounds structures of dermis, including hair follicles, sebaceous glands, sweat glands, nerves and blood vessels and helps provide structure and support Lines of Cleavage and Stretch Marks Majority of collagen and elastic fiber s in skin are oriented in parallel bundles Function of the bundles is to resist stress Lines of cleavage (tension lines) identify the predominant orientation of collagen fiber bundles If you cut perpendicular to a cleave line, it can result in slowed healing and increased scarring Collagen fibers provide tensile strength Elastic fibers allow for stretch and recoil When skin is stretched beyond its capacity, some collagen fibers are torn and result in stretch marks called STRIAE UV light and aging can affect flexibility and thickness of skin, causing sagging/wrinkled skin. Subcutaneous Layer Deep to the integument, also called hypodermis or superficial fascia Not considered part of the integument Consists of areolar connective tissue and adipose connective tissue Can be referred to as subcutaneous fat if adipose predominates in certain part of the body Connective tissue fibers of the reticular layer of the dermis are interwoven with the hypodermic to stabilize the skin and help bind it Subcutaneous layer provides protection, an energy reservoir, and thermal insulation.  Drugs are often inserted into this layer due to its immense vascular network that promotes rapid absorption FUNCTIONS OF THE INTEGUMENT Protection from external environment o Physical barrier against chemicals, toxin, microbes and heat/cold o Protects deeper tissue from solar radiation o When exposed to sun, melanocytes produce melanin Prevent water loss and gain o Epidermis is water resistant o Water can be tossed through sweat or transpiration (fluids slowly leave and evaporate) o Ex. People with severe burns can suffer dehydration o Prevents water gain (don’t want to swell like a sponge when bathing)  Vitamin D synthesis o Keratinocytes covert steroid molecules to vitamin D3 in response to UV light exposure o Vitamin D3 is released into blood and goes to liver (converted to calcidiol) o Calcidiol is transported to kidney where it converted to calcitriol (active form of vitamin D) o It increases absorption of calcium and phosphate in the small intestine o Only need 10 - 15mins of sunlight a day Secretion o Production and release of substances by a cell or gland o Sweating releases excess heat o Sweat contain water, salts and urea o Secretes sebum (lubricates skin and hair, and makes skin water resistant) Sweat glands and sebaceous glands are controlled by nervous system Absorption o Skin can absorb certain drugs (ex. Estrogen or nicotine) o Skin is Selectively permeable o Transdermal administration - drugs given transdermally by adhesive patch o Drugs slowly penetrate epidermis and absorb into blood vessels of dermis o Slow absorption over long time o Small and non polar molecules Temperature regulation o Body temps can be influenced by capillary network and sweat glands o Dermal vessels can vasoconstrict to conserve heat (pale face when cold) o Vasodilation to release excess heat (red face when exercising) o Sweating to cool the body Immune functions o Epidermal dendritic cells and dendritic cells of the dermis attack against epidermal cancer cells Sensory perception o Tactile sensory receptors detect stimuli o Contain 7 major types of sensory receptors INTEGUMENTARY STRUCTURES DERIVED FROM EPIDERMIS Nails, hair, exocrine glands are derived from epithelium that forms the dermis (epidermal derivatives) Form during embryology development Nails and hairs composed of primarily dead keratinocytes Exocrine glands composed of living epithelia cells NAILS Scalelike modifications of the stratum corneum Forms on the dorsal edges of the fingers and toes Protect distal tips of digits Fingernails help us grasp objects Each nail has distal, light colored free edge, darker nail body, and nail root (proximal part embedded in skin) ^forms nail plate Nail body covers nail bed, contains deeper living cell layers  Nail body appears darker/pinkish because of the blood flowing in the underlying capillaries Free edge has no capillaries and is lighter Nail matrix o Located at nail root and proximal end of nail body o Actively growing part of the nail The lunula is the whitish semilunar area at the proximal end of the nail body. has a thickened stratum basale that obscures the underlying blood vessels. Nails folds o Located at proximal and lateral borders of nail Eponychium/cuticle - narrow band of epidermis extending from the nail wall to the nail body Hyponychium - area of thickened epithelium underlying the free edge of the nail HAIR Found almost everywhere except palms, fingers, sides and soles of feet/toes, and portions of the external genitalia Hair type and distribution A hair/pilus - shaped like a slender filament Composed of keratin cells that extend from the hair follicles to dermis and subcutaneous layer Differences in hair density are due to difference in the texture and pigmentation 3 types of hair o Lanugo - fine, unpigmented, appears on the fetus in last trimester. Replaced by villus at birth. o Vellus - unpigmented or lightly pigmented hair, primary human hair, found on upper and lower limbs o Terminal - coarser, pigmented and longer. Grows on scalp, eyebrows and eyelashes. During puberty, grows in axillary and pubic regions, and forms beards. Hair Structure and Follicles 3 zones along the length of a hair o Hair bulb - Consists of living epithelial cells, swelling at the base in the dermis. Surrounds hair papilla with small amounts of connective tissue with tiny blood vessels and nerves o Hair root - Zone of hair extending from bulb to skin surface. Contains dead epithelial cells o Hair shaft - Extends beyond skin surface. Contains dead epithelial cells Hair production Special type of keratinization in hair matrix (in hair bulb) Medulla - contains flexible, soft keratin Cortex - several layers of flattened cells on the surface of the hair Hair follicle - an oblique tube that surrounds the hair root Extends into the dermis/hypodermis 2 layers o outter connective tissue root sheath (originated from dermis o Inner epithelial tissue root sheet (originates from epidermis) Arrestor pili - stimulated by emotional states such as rage, or response to temperature Goose bumps - formed by arrestor pili contracting by stimulation from nervous system Functions of Hair Protection - protects scalp from sunburn and injury Hair in nostrils trap particles and prevents them from entering respiratory system Hair in external ear canal protect from insects and particles Eyelashes protect eyes Heat retention - hair on head prevents loss of heat Sensory reception - have tactile receptors to detect light touch Visual identification - important to determine age and to identify people Hair color Determined by melanin in the hair matrix Variations in hair color reflect genetic differences in the structure of melanin Environmental/hormonal factors can affect hair As people age, production of pigment decreases and hair becomes lighter (grey hair from decrease in pigment, white hair from no melanin) Hair Growth and Replacement 3 stages o Anagen phase - active phase of growth. Living cells of hair bulb growing and dividing into hair. Longest part of hair growth (~18months - 7years) Most hairs on scalps are in anagen phase o Catagen phase - brief period where cell division decreases, follicle undergoes involution. Short phase (3-4weeks) o Telogen phase - resting phase, phase where hair is shed. After 3-4 months, hair bulb starts to regrow and follicle reenters anlagen phase Hair growth rate and duration of hair growth cycle vary Scalp loses about 10 to 100 hair per day (more than 100 is a problem) Temporary hair loss (drugs, diet, radiation stress, fever) Alopecia aerate - circular bald patches, occurs in anyone o Autoimmune disorder where body mistakes follicles as foreign and attacks them Diffuse hair loss - hair shed from all parts of scalp Male pattern baldness - loss of hair from crown region caused by genetics and hormone Gene for male pattern baldness is dominant, expressed in the presence of high testosterone, causes hair to be thinner.  Hirsutism - excessive hair growth in atypical areas, Face, chest, bac. Excess of male sex hormones EXOCRINE GLANDS OF SKIN Skin houses many of these glands, most common are sweat glands and sebaceous glands Sweat Glands 2 types, merocrine sweat glands and apocrine sweat glands Both have a coiled, tubular secretory portion located in the reticular layer of the dermis and a sweat gland duct connected to the epidermis (merocrine sweat gland) or into a fair follicle (apocrine sweat gland) Sweat pore - opening of a sweat gland duct on epidermal surface Both glands contain myoepthilial cells (specialized epithelial cells with contractile proteins like muscle) that are sandwiched between secretory glands and basement membrane. they squeeze the gland, causing it to discharge secretions. Merocrine Sweat Glands Most numerous and widely distributed sweat glands Simple, coiled tubular glands Discharge secretions on the surface of skin Clear secretions – sweat Uses exocytosis Major function is thermoregulation Loses water and electrolytes Helps eliminate ingested drugs Antibacterial and anti fungal activity Apocrine Sweat Glands Coiled, tubular glands Release secretions into hair follicles around the axillae, nipples, pubic region, and anal region Uses exocytosis Much larger lumen Viscous, cloudy secretion contains proteins and lipids that produce odor Become more active during puberty Sebaceous Glands Holocene glands Produce oliy, waxy secretions called sebum Secretes sebum into hair follicles Sebum lubriates skin and hair Has bactericidal properties Secretion is stimulated by hormones, mostly male sex hormones Active during puberty Other integumentary Glands  Cernumious glands o Modified apocrine sweat glands o Located in external acoustic meatus (ear) o Produce cerumen o Helps trap foreign particles/insects o Provides lubrication Mammary glands o Modified apocrine sweat glands o Only become function in pregnant and lactating females o Produces breast milk o Controlled between gonadal and pituitary hormones REPAIR AND REGENERATION FO THE INTEGUMENTARY SYSTEM Mechanical stresses stimulate cell division in the stem cells of the stratum basale Causes epidermis to thicken and improves ability to withstand stress Damaged tissue repaired in 2 ways o Regeneration - replaced of damaged/dead cell with same cell by cell division. Restores tissue function o Fibrosis if organ it too damages or cells can’t divide ▪ Body fills gap with scar (fibrous) tissue. Composed of collagen fibers. Produced by fibroblasts of connective tissue. Functional activities not restored Stages of wound healing Cut Blood vessels release blood into wound and brings proteins, leukocytes and antibodies Blood clot forms and acts as barrier to protect against pathogens. Macrophages and neutrophils clean the wound Cut blood vessels regenerate and grow in wound. Granulation tissue forms (vascular connective tissue formed during wound healing). Macrophages remove clotted blood and fibroblasts create new collagen fibers Epithelial cells at the edge of the wound divide and cover the wound, and then move internally to the old remains of the clot. Connective tissue is replaced by fibrosis. Somethings cannot be repaired following severe skin damage including hair follicles, exocrine glands, nerves and arrestor pili muscle cells. DEVELOPMENT AND AGING OF THE INTEGUMENTARY SYSTEM The integumentary system structures are derived from ectoderm and mesoderm germ layers o Ectoderm - origin of epidermis o Mesoderm - origin of dermis DEVELOPMENT OF THE INTEGUMENT AND ITS DERIVATIVES By end of week 7 of development, ectoderm forms a layer of squamous epithelium that becomes the periderm (covering layer) and an underlying basal layer Basal layer forms into stratum basale and other epidermal layers Week 21 - stratum corner and friction ridges form Fetal period (weeks 9 - 38) periderm is sloughed off, mixes with sebum from the sebaceous glands and for the vernix cases, a waterproof coat that coats the skin of the fetus Dermis derived from mesoderm In weeks 3 - 8, mesoderm becomes mesenchyme, and they begin to form the dermis around 11 weeks Fingernails and toenails - form around 10 weeks. fingernails reach tips around 32 weeks. Toenails fully form around 36 weeks. Hair follicles - appear around 9 - 12 weeks as hair buds invade the dermis. Does not become recognizable until about 20 weeks. Sweat and sabeous glands form from the stratum basale of the epidermis and appear around 20 weeks. AGING OF THE INTEGUMENT Most skin changes are not noticeable until middle age because reduced number/activity of stem cells. Skin repair processes take about 3 weeks in young adults and double in older adults. Reduced stem cell activity in dermis - thinner skin As you age, collagen fibers decrease, and elastic fibers lose elasticity Facial expressions produce crease lines Epidermal dendritic cells are decreased, and immune responses decrease Hair follicles produce thinner hair or stop production entirely Smoking and overexposure to UV rays can damage epidermal DNA cells and accelerate aging. P53 skin gene, risk factor for cancer Uv exposure - biggest risk factor for skin cancers Skin cancer - most common type of cancer  Occurs mostly on the head and neck regions Risk increases as we age