Module 7.1: The Integumentary System PDF
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This document provides information about the integumentary system, focusing on the skin and its various components and functions. It details the structure, layers, and functions of the skin, addressing its roles in protection, excretion, temperature regulation, and sensation. Key elements like the chemical, physical, and biological factors in skin are discussed.
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MODULE 7.1: THE INTEGUMENTARY SYSTEM eratinized Cells: It is found in the stratum K T HE SKIN...
MODULE 7.1: THE INTEGUMENTARY SYSTEM eratinized Cells: It is found in the stratum K T HE SKIN corneum layeroftheepidermisandprovidesa It consists of the cutaneous membrane and its physical barrier against most invasions. accessory organs and comprises three layers of tissue. The Biological Factor uter Epidermis: Made of stratified squamous O hite Blood Cells: Macrophages destroy most W epithelium invaded bacteria and other foreign substances. Middle Dermis:Made of fibrous connective tissue xcretion: Wastematerialssuchasammonia,urea, E and excessive salt are eliminated from sweating. ypodermis: It is also known as the inner H subcutaneous layer. ody Temperature Regulation: There are three: B sweating, vasoconstriction, and vasodilation. T he skin also contains several accessory organs, whichincludethehair(hairrootandhairshaft),hair weating: This isdonebythesweatglandsand S follicle, pili arrector muscle, sebaceous gland, it promotes evaporation, resulting in a loss of sudoriferous gland (sweat gland), nails, and the excessive body heat. mammary gland. asoconstriction By Arterioles: Vasoconstriction V is done by small arteries in the dermis layer, FUNCTIONS OF THE INTEGUMENTARY SYSTEM which provides a smaller surface area in the blood vessels, resulting in less heat loss. rotection: There are three factors, which include P thechemical,physical,andbiologicalfactorsinthe asodilatation By Arterioles: Vasodilatation in V skin. the dermis layer providesalargersurfacearea in the blood vessels, resulting in greater heat The Chemical Factors loss. ebum (or oil): From the sebaceous glands is S utaneous Sensation: These are any of the senses C slightly acidic, retarding bacterial colonization that are dependent on receptors in the skin on the skin surface. sensitive to contact, pressure, vibration, temperature, or pain. weat from Sudoriferous Glands: It is slightly S hypertonic and can flush off most bacteria on erve Receptors:Thesearefoundinthedermis N the skin's surface. layersanddetectsensationssuchasheat,cold, pain,pressure,andtouch,allowingthebodyto elanin (skin pigment): From melanocytes, M be aware of these stimuli. avoid excessive ultraviolet radiation that penetrates the skin layers. itamin D Synthesis: Theepidermallayerofhuman V skin synthesizes vitamin D when exposed to UV The Physical Factors radiation. In the presence of sunlight, a form of vitaminD3 calledcholecalciferolissynthesizedfrom tratifiedsquamousepithelium:Itisfoundinthe S a derivative of the steroid cholesterol in the skin. epidermis layer and provides many layers of cells, preventing most bacterial invasion. 15 ltraviolet Radiation: It results in Vitamin D U nd allow the epidermistobecomeastronger a through a series of chemical reactions physical barrier. activated by sunlight. Thisisduetoachemical modification of cholesterol to absorb calcium. THICK SKIN VS THIN SKIN EPIDERMIS: CHARACTERISTICS tratum Lucidum: It is only found in the palms and S It is made of stratified squamous epithelium. It has soles, It is an extra thin layer beneath the stratum no blood vessels to supply nutrients to itscells.The corneum is formed. epidermissurfaceofthebodyhasfourlayerofcells: stratum basale, stratum spinosum, stratum T hick skin has all 5layers.Itisfoundinareaswhere granulosum, and stratum corneum. there is a lot ofabrasion.Itisnormallyfoundinthe fingertips, palms, and the soles of feet. utrients from the arterioles in the dermis layer N diffuse upward into the epidermis layer, especially T hinskinonlyhas4layers.Itisthinduetothestratum to the stratum basale and spinosum layers. lucidum being absent. EPIDERMIS: SPECIALIZED CELLS elanocytes:Specializedcellsinthestratumbasale M layerthat produce the skin pigment,melanin. T he number of melanocytes and the amount of melaninproductionaregeneticallyinherited.Italso protects the DNA in the nuclei of cells. tratumBasale(orStratumGerminativum):Thelayer S ERMIS: CHARACTERISTICS D receives most of the nourishment. It is made of fibrous connective tissue. It also Cuboidal cells contains arterioles for supplying nutrients to its Reproduce rapidly using mitosis structures and to the epidermis. New cells will be pushed upward and become flattened as they move upward S quamous cells moving upward in the epidermis receive less and less nutrients as diffusion distance increases. tratumCorneum:Bythetimethesesquamouscells S form the stratum corneum, thecellsaredeadand will be shed off. eratinization: Cells in the stratum granulosum K and stratum corneum undergo this process. Produces a protein called keratin This allows cells to be tough and waterproof. ili Arrector Muscles: It wrinkles the skinanderects P T hese cells are now called “k eratinocytes.” the hairs. These develop desmosomes between the cells 16 Hair Follicles:These are what develop into hair. nagen Phase: Lasts around 2-6 years. This is A where active growth and the production of erves and Nerve Receptors: These detect the N new cells occur. sensations of heat, cold, pressure, touch, and pain. atagen Phase: Lasts around 2-4 weeks. This is C ebaceous Gland: These secrete sebum onto skin S where growth stops due to the hair papilla surface (acidic environment). detaching from the hair follicle. udoriferous Glands: These S secrete sweat T elogen Phase: Lasts around 3-5 months. This is (hypertonic environment). wherethefolliclerestsandpreparesforthenext cycle of growth. Also called “resting” or YPODERMIS: CHARACTERISTICS H “shedding.” It is made of adipose tissue and loose connective tissue. The collagen and elastic fibers in the loose iliArrectorMuscle:Itismadeofskeletalmusclebut P connective tissue are continuous with the fibers in under involuntary control. It is attached to each the dermis layer. hair follicle,for erecting the hair. dipose Tissue: These act as a heat insulator A S ituations such a s extreme emotions o r extreme against the cold climate and as fat storage. temperatures can activate its involuntary contraction. L ooseConnectiveTissue:Theseallowtheskintobe bound with underlying muscles. ebaceous Gland: It is an oil gland made of S modifiedcuboidalepithelium.Itoccursalloverthe T he hypodermis also contains large blood vessels bodyexcept in the palm and sole. (arteries and veins). It is attached to each hair follicle so that sebum ACCESSORY STRUCTURES OF THE SKIN can be secreted into the hair root and diffuse upward. air: It is produced by epithelial cells at the hair H papilla.Itismadeofkeratinizedcells.Italsoconsists ebum: It helps the skin and hair to be S of two regions: waterproofandretardsbacterialgrowthonskin surface (due to its acidity). air Root: Located in the hair follicle and it is H embedded in the dermis layer. udoriferous Gland: It is the sweat gland that S secretes sweat to promote evaporation.Itisfound air Shaft: Protruded through the epidermis to H all over the body except the lips, nipples, and the outside external genitalia. air pigment or melanin is produced by H Itisalsoreferredtoas“t ubulargland”wherealong melanocytes in the hair papilla. Hair growth is tubule coiled in the dermis layer, uses alongduct affected by nutrition and hormones. (i.e. to release sweat onto skin surface through a pore. testosterone). ails:Itisascale-likemodificationofepithelialcells N The Hair Cycle in the epidermis. It is made of keratin. T he nails protect the ends of fingers and toe and prevent over sensitization of thenervereceptorsin 17 xtremities.Growingcellsarederivedfromthebase e It moves the bones and thebody,aswellasitisa of the nail or lunula. bundle of long fibers running paralleltothelength of the muscle. BURNS arcomere:Itisthefunctionalunitofthemuscle.Itis S st Degree Burns: Only the epidermis is damaged 1 bordered by Z linesand ismade up of myofibrils. with redness and swelling. nd DegreeBurns:Theepidermisandupperregion 2 of dermisisinvolved.Thereisredness,swelling,and blisters. rdDegreeBurns:Alllayersofskinareburned.Askin 3 graft is necessary to repair. The skin would look cherry red or blackened. KIN CANCER S Mostskintumorsarebenign.Thecauseofcanceris unknown but is probably due to overexposure to The Sliding-Filament Model of Muscle Contraction ultraviolet radiation in the sunlight. T hin & Thick Filaments: Thin (actin) and thick asal Cell Carcinoma: It is themostcommontype B (myosin) filaments slide past each other and is usually benign. The cells of stratum basale longitudinally. are affected, as a result they cannot form keratin and begin to invade into the dermis. Surgical T he“head”ofamyosinmoleculebindstoanactin removal (in early detection) is 99% successful. filament,formingacross-bridgeandpullingthethin filament toward the center of the sarcomere. quamous Cell Carcinoma: It arises from S keratinocytes in stratum spinosum. It is mostly lycolysis & Aerobic Respiration: These generate G detected in thescalp,ears,orhands.Itgrowsand the ATP needed to sustain muscle contractions. migrates rapidly. Early detection is critical for successful treatment. alignantMelanoma:Itisthemostdangerousand M it is the cancer of the melanocytes in the stratum basale. It is only 5% of all skin cancer but the frequency is increasing. It grows and migrates extremely rapidly.Usually deadly. MODULE 7.2: THE MUSCULOSKELETAL SYSTEM VERTEBRATE SKELETAL MUSCLE Itisalsocalledstriatedmusclebecauseofthelight and dark bands. The Role of Calcium and Regulatory Proteins T ropomyosin & Troponin Complex: These bind to actin strands onthinfilamentswhenamusclefiber 18 is at rest. This prevents actin and myosin from interacting. ummation: The term for more rapid delivery of S action potentials that produce a graded F or a muscle fibertocontract,myosin-bindingsites contraction by summation. must be uncovered. Thisoccurswhencalciumions(Ca2+)bindto T etanus: It is a state of smooth and sustained the troponin complex and expose the contraction produced whenmotorneuronsdeliver myosin-binding sites. a volley of action potentials. ervous Control of Muscle N In vertebrates, each motor neuron may synapse with multiple muscle fibers. TYPES OF SKELETAL MUSCLE FIBERS It is classified by the source of ATP powering the muscle activity or by the speed of muscle otor Unit: It consists ofasinglemotorneuronand M contraction. all the muscle fibers it controls. ction Potential: This is produced by a motor A unit and it results in all muscle fibers within the motor unit to contract. ervous Control of Muscle Tension N Contraction of a whole muscle is graded, which means that the extent and strength of its contraction can be voluntarily altered. T here are two basic mechanisms by which the nervous system produces graded contractions. No. of Contracted Fibers: Varying the number of fibers that contract Stimulant: Varying the rate at which fibers are stimulated. ecruitment: The recruitment of multiple motor R neurons results in stronger contractions. T witch: It results from a single action potential in a In terms of source of ATP motor neuron. 19 xidative Fibers: It relies mostly on aerobic O S keletal systems transform muscle contraction into respiration to generate ATP. It has many locomotion mitochondria, a rich blood supply, and a large amount of myoglobin. keletal Muscles: These are attached in S antagonistic pairs, the actions of which are yoglobin: This is a protein that binds oxygen M coordinated by the nervous system. more tightly than hemoglobin does. T he skeleton provides a rigid structure to which lycolytic Fibers: It uses glycolysis as their primary G muscles attach. source of ATP. It has lessmyoglobinthanoxidative fibers and tire more easily. TYPES OF SKELETAL SYSTEMS It is composed of hydrostatic skeletons (lack hard In poultry and fish, light meat is composed of parts), exoskeletons (external hard parts), and glycolytic fibers, while dark meat is composed of endoskeletons (internal hard parts). oxidative fibers. ydrostatic Skeletons: These consist of fluid held H In terms of speed of muscle contraction under pressureinaclosedbodycompartment.Itis the main type of skeleton in most cnidarians, ostskeletalmusclescontainbothslow-twitchand M flatworms, nematodes, and annelids. fast-twitch fibers in varying ratios. eristalsis:Annelidsusetheirhydrostaticskeleton P low-twitch Fibers: It contracts more slowly but S forperistalsis,atypeofmovementproducedby sustains longer contractions. All are oxidative fibers. rhythmic waves of muscle contractions from front to back. F ast-twitch Fibers: It contracts more rapidly but sustains shorter contractions. It can be either xoskeletons:Ahardencasementdepositedonthe E glycolytic or oxidative. surface of an animal. It is found in most molluscs and arthropods. Inproducingitscharacteristicmatingcall,themale toadfish can contract and relax certain muscles rthropods: They have a jointed exoskeleton A more than 200 times per second. calledacuticle,whichcanbebothstrongand flexible. OTHER TYPES OF MUSCLES The polysaccharide chitinisoftenfound in arthropod cuticles. ardiacMuscle:Itisfoundonlyintheheart,consists C of striated cells electrically connected by ndoskeletons:Itconsistsofahardinternalskeleton, E intercalateddisks.Itcangenerateactionpotentials buried insofttissue.Itisfoundinorganismsranging without neural input. from sponges to mammals. mooth Muscle: It isfoundmainlyinwallsofhollow S mammalian skeleton has more than 200 bones. A organs such as those of the digestive tract. Its Some bones are connected at joints by ligaments contractions are relatively slow and may be that allow freedom of movement. initiated by the muscles themselves. The contractions may also be caused by stimulation from neuronsin the autonomic nervous system. 20 T YPES OF LOCOMOTION Mostanimalsarecapableoflocomotion,oractive travelfromplacetoplace.Inlocomotion,energyis expended to overcome friction and gravity. It is classified by the locationat which it occurs. L ocomotion on Land:Walking,running,hopping,or crawlingonlandrequiresananimaltosupportitself and move against gravity. iverse adaptations for locomotion on land have D evolved in vertebrates. Theairposesrelativelylittle resistance. aintaining balance is a prerequisite for walking, M running, or hopping. Crawling animals must exert energy to overcome friction. wimming:Frictionisabiggerproblemthangravity S underwater. Fast swimmers usually have a sleek, torpedo-like shape to minimize friction. Animals swim in diverse ways: Paddling with their legs as oars Jet propulsion Undulating their body and tail from side-to-side or up and down F lying: Active f light requires that wings develop enough lift to overcome the downward force of gravity. any flying animalshaveadaptationsthatreduce M body mass. Birds have no urinary bladder or teeth and have relatively large bones with air-filled regions. 21
