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ORGAN systemS INTEGUMENTARY SYSTEM 1 2 Skin • largest organ in the body: 12-15% of body weight, with a surface area of 1-2 meters • continuous with, but structurally distinct from mucous membranes that line the mouth, anus, urethra, and vagina • distinct layers occur in the skin: the dermis and epidermis • basic cell type of the epidermis is the keratinocyte, which contain keratin, a fibrous protein 3 Skin • basal cells are the innermost layer of the epidermis • melanocytes produce the pigment melanin, and are also in the inner layer of the epidermis • dermis is a connective tissue layer and contains nerve endings, sensory receptors, capillaries and elastic fibers 4 Multiple Roles • • • • • protection temperature regulation sensory reception biochemical synthesis absorption 5 Follicles and Glands • Hair follicles are lined with cells that synthesize the proteins that form hair • A sebaceous gland (that secretes the oily coating of the hair shaft), capillary bed, nerve ending, and small muscle are associated with each hair follicle • If the sebaceous glands becomes plugged and infected, it becomes a skin blemish (or pimple) 6 7 Follicles and Glands • sweat glands open to the surface through the skin pores • Eccrine glands • a type of sweat gland linked to the sympathetic nervous system • occur all over the body • Apocrine glands • larger and occur in the armpits and groin areas • produce a solution that bacteria act upon to produce "body odor" 8 Hair and Nails • hair, scales, feathers, claws, horns, and nails are animal structures derived from skin • hair shaft extends above the skin surface, the hair root extends from the surface to the base or hair bulb • Genetics controls several features of hair: • baldness, color, texture • Nails consist of highly keratinized, modified epidermal cells • arises from the nail bed, which is thickened to form a lunula (or little moon) • Cells forming the nail bed are linked together to form the nail 9 10 Skin and Homeostasis • Skin functions in homeostasis include protection, regulation of body temperature, sensory reception, water balance, synthesis of vitamins and hormones, and absorption of materials • The skin's primary functions are to serve as a barrier to the entry of microbes and viruses, and to prevent water and extracellular fluid loss • Acidic secretions from skin glands also retard the growth of fungi • Melanocytes form a second barrier: protection from the damaging effects of ultraviolet radiation • When a microbe penetrates the skin (or when the skin is breached by a cut) the inflammatory response occurs 11 Skin and Homeostasis • Heat and cold receptors are located in the skin • When the body temperature rises, the hypothalamus sends a nerve signal to the sweat-producing skin glands, causing them to release about 1-2 liters of water per hour, cooling the body • The hypothalamus also causes dilation of the blood vessels of the skin, allowing more blood to flow into those areas, causing heat to be convected away from the skin surface • When body temperature falls, the sweat glands constrict and sweat production decreases • If the body temperature continues to fall, the body will engage in thermiogenesis, or heat generation, by raising the body's metabolic rate and by shivering 12 Skin and Homeostasis • • • • Water loss occurs in the skin by two routes: evaporation sweating In hot weather up to 4 liters per hour can be lost by these mechanisms • Skin damaged by burns is less effective at preventing fluid loss, often resulting in a possibly life threatening problem if not treated 13 • Homeostasis • (from Greek: ὅμος, homos, "equal"; and ιστημι, histemi, "to stand" lit. "to stand equally"; coined by Walter Bradford Cannon) • the property of either an open system or a closed system, especially a living organism, that regulates its internal environment so as to maintain a stable, constant condition 14 15 Skin and Sensory Reception • Sensory receptors in the skin include those for pain, pressure (touch), and temperature • Deeper within the skin are Meissner's corpuscles, which are especially common in the tips of the fingers and lips, and are very sensitive to touch • Pacinian corpuscles respond to pressure • Temperature receptors: more cold ones than hot ones 16 Skin and Synthesis • Skin cells synthesize melanin and carotenes, which give the skin its color • The skin also assists in the synthesis of vitamin D • Children lacking sufficient vitamin D develop bone abnormalities known as rickets 17 Skin Is Selectively Permeable • The skin is selectively soluble to fat-soluble substances such as vitamins A, D, E, and K, as well as steroid hormones such as estrogen • substances enter the bloodstream through the capillary networks in the skin • Patches have been used to deliver a number of therapeutic drugs • include estrogen, scopolamine (motion sickness), nitroglycerin (heart problems), and nicotine (for those trying to quit smoking) 18 MUSCULAR SYSTEM 19 Muscles • • • • • • • the "machines" of the body help move food from one organ to another carry out our physical movement three different kinds of muscles in our body: cardiac smooth skeletal 20 Cardiac • involuntary and found only in the heart • controlled by the medulla oblongata, which controls involuntary action throughout the body • single-nucleated long strip heart cells, one of the key factors in determining which of the three classes any particular muscle is • located at the walls of the heart • main function: to propel blood into circulation • Contraction: impulse sent from the medulla oblongata to the SA nerve located at the right atrium (linkcirculatory) 21 22 Smooth • • • • involuntary make up the internal organs generally spherical each contains one nucleus 23 24 Skeletal • the only voluntary muscles of your body, and make up the muscular system • the muscles that move the bones and show external movement • contain multiple nuclei because of its large size, being in strips up to a couple of feet long 25 26 Flexors • Flexors bend at the joint, decreasing the interior angle of the joint • humorous, or bicep, is a flexor of the elbow joint, bringing the fist towards the shoulder • If a flexor appears in either the wrist or ankle joints, it becomes a plantar flexor 27 28 Extensors • unbend at the joint, increasing the interior angle • humorous, or tricep, is an extensor of the elbow joint, taking the fist farther away from the shoulder • if an extensor is found in the wrist or ankle joints, it becomes a dorsiflexor 29 30 • • • • • • • • Abductors take away from the body, like lifting the arm to the side Abd- means to take away, like abduct and abdicate Spreading out of fingers uses abductors Adductors move toward the body Add- means to increase or include By lowing an arm raised to the side, or moving your fingers together while keeping them straight, your muscles are adducting 31 Tendons and Ligaments • muscles alone can't do the job • at every joint, tendons and ligaments also help out • muscles are connected to tendons, when themselves are connected to the bones • when the muscles contract, they pull on the tendons, which in turn pull on the muscles, and that causes movement 32 What if there are no ligaments… • movement wouldn't be too useful because it would not be directed movement • bones would slide by each other • Ligaments are what hold the bones together • Ligaments connect at the ends of muscles and keep them from slipping and sliding, and force them to bend 33 Major Skeletal Muscles • Facial • Orbicularis oculi-are the two muscles that move the eye are • Frontalis- and Temporalis- are the two muscles which move the forehead and sides of your head • Zygomaticus- and Masseter- are the two muscle that work in conjunction to move the jaw and upper lip area • Orbicularis oris- is the muscle which moves your lips 34 Neck • almost entirely moved by the sternohyoid and sternocleidomastoid • allow the neck to move your head left and right • control how far you can move your head left and right • what allows your head to move up and down is the trapezius • it extend down to the shoulder and thorax area 35 Major Skeletal Muscles • Shoulder • trapezius, deltoid, infraspinatus, teres major, and the rhomboid major • ball and socket joint shoulder muscles allow your arm to throw a softball, pick things over your head, and give your arms a good stretch earlyinthe morning • Arm • bicep brachii is the muscle that allows you to bring your forearm close to your body and form a huge ball of muscle which catches a lot of attentionamongstweightlifters • tricep brachii and brachialis are the two other muscles located in the arm region – allowapersontodopush-ups 36 Forearm • • • • help control a part of the arm Berachiodialis major palmaris longus Flexor carpi radialis – a good example of how muscles are named by their function and location – named carpi because of the bones that it helps move, the carples – name of radialis is made by the bone that its attached to, the radius 37 • Thorax • set of muscles which carrying your head, arms, stomach, and any other upper body areas • trapezius and latissimus dorsi • muscles can be damaged easily if one dose not stretch before exercise, or lifts a heave load • Abdomen • allows you to bend down and move your waist from side to side • internal oblique and external oblique are the muscles that move your body from left to right • transversus abdominus and rectus abdominus along with the trapezius and latissimus dorsi allow you to bend down and grab objects 38 • • • • • • • • • • Hip gluteusmedius-and gluteusmaximus the gluteusset ofmusclesare used onlytosit downon Pelvis/Thigh pelvisareais usually referredtoas the upper partof the leg pectineus and illiopsoas which help support the upper leg area are knownas pelvicmuscles. thighmuscles are veryrich incapillariesand supportthe wholebody upper thigh muscles are abductor longus, gracilis, sartorius, and tensorfasciaelatea lowerthighmuscles are rectusfemoral, vastuslateralisandmedialis the hamstrings-soundmuscles help you run, jump, and walk 39 Leg • gastrocnemius, soleus, porenius longus, and tibialis anterior absorb the impact when one walks and runs • give better coordination for moving • trust the body forward while the leg region coordinates where it should be thrusted and where it should stand 40 SKELETAL SYSTEM 41 What is the Skeletal System? • all of the bones in the body and the tissues such as tendons, ligaments and cartilage that connect them • teeth are also considered part of the skeletal system but they are not counted as bones • teeth are made of enamel and dentin • enamel is the strongest substance in your body 42 How does the Skeletal System help us? • • • • • • • • • Support provide support for the body Protection helps protect your internal organs and fragile body tissues cranium (skull) protects brain and eyes ribs protect heart and lungs vertebrae (spine, backbones) protect spinal cord Movement provide the structure for muscles to attach so that our bodies are able to move • tendons are tough inelastic bands that hold attach muscle to bone 43 Who has more bones a baby or an adult? • babies have more than adults • at birth, babies have about 300 bones • as babies grow older, small bones join together to make big ones • adults end up with about 206 bones 44 Are bones alive? • • • • • absolutely old bones are dead, dry and brittle in the body, bones are very much alive have their own nerves and blood vessels do various jobs, such as storing body minerals like calcium • bones are made of a mix of hard stuff that gives them strength and tons of living cells which help them grow and repair themselves 45 What is a bone made of? • an outer layer of hard or compact bone, which is very strong, dense and tough • an inner layer of spongy bone, which is like honeycomb, lighter and slightly flexible • in the middle of some bones is jelly-like bone marrow, where new cells are constantly being produced for the blood • calcium is an important mineral that bone cells need to stay strong so keep drinking that low-fat milk 46 • How do bones break and heal? • bones are tough and usually don't break even when we have some pretty bad falls • bones will bend a little, but if you fall the wrong way from some playground equipment or maybe your bike or skateboard you can break a bone • doctors call a broken bone a fracture • when a bone is broken your bone will produce lots of new cells to rebuild the bone • these cells cover both ends of the broken part of the bone and close up the break 47 • How do I keep my bones healthy? • walking, jogging, running and other physical activities are important in keeping your bones strong and healthy • riding your bike, basketball, soccer, gymnastics, baseball, dancing, skateboarding and other activities are all good for your bones • strengthen your skeleton by drinking milk and eating other dairy products (low-fat cheese, frozen yogurt, ice cream) • all contain calcium, which helps bones harden and become strong 48 Joints • • • • • • • three structural classifications of joints: fibrous joint – - joined by fibrous connective tissue cartilaginous joint – - joined by cartilage synovial joint – - not directly joined 49 • Functional classification • can also be classified functionally, by the degree of mobility they allow: • synarthrosis - permits little or no mobility • fibrous joints (skull) • amphiarthrosis - permits slight mobility • cartilaginous joints (e.g. Vertebrae) • diarthrosis - permits a variety of movements • synovial joints (e.g. shoulder, hip, elbow, knee etc.) 50 • Biomechanical classification • subdivided into simple and compound, depending on the number of bones involved, and into complex and combination joints: • Simple Joint: 2 articulation surfaces (eg. shoulder joint, hip joint) • Compound Joint: 3 or more articulation surfaces (e.g.. radiocarpal joint) • Complex Joint: 2 or more articulation surfaces and an articular disc or meniscus (eg. knee joint) 51 Anatomical Classification • • • • • • articulations of hand elbow joints wrist joints axillary articulations sternoclavicular joints vertebral articulations • temporomandibular joints • sacroiliac joints • hip joints • knee joints • articulations of foot 52 Gait • manner of walking • any part of the foot or hand comes in contact with the ground when the animal walks 53 Plantigrade • entire sole of the foot touches the ground as in man, ape, bears, racoons • the most primitive type 54 Digitigrade • digits which are provided with pads touch the ground and the rest of the foot is elevated • members of the cat family 55 Unguligrade • tips of the digits touch the ground and are specialized hoofs • cows, carabaos, pigs, goats, etc. 56 Gait 57 Synarthroses or Immovable Joints • Bones are connected by fibrous tissue or cartilage like sutures which are the lines of junction of the skull bones 58 Amphiarthroses or Slightly Movable Joints • Symphysis – a joint where two long bony surfaces are connected by a broad, flat disc of fibrocartilage • Synchondrosis – a temporary form of joint made of cartilage which in the adult is changed to bone as found between the epiphysis and bodies of long bones 59 60 Diarthroses or Freely Movable Joints • Gliding – permit gliding movement only – Joints between carpal bones of the wrist – Between the tarsal bones of the ankle – Between the articular processes of the vertebrae • Hinge – allow angular movement in one direction – Between humerus and ulna – In the knee and ankle joints, phalanges 61 • Condyloid – angular movement in two directions – Wrist joint • Saddle – has articular surfaces which is concave in one direction and convex in another – Trapezium bone of the carpus • Pivot – rotary movement in one axis – Atlas and axis – Radius and ulna 62 Ball and Socket • • • • Angular movement in all directions Head of the femur in the acetabulum Head of the humerus in the glenoid cavity Shoulder joint 63 Reproductive System 64 Introduction • reproductive system is a system of organs within an organism which work together for the purpose of reproduction • fluids, hormones, and pheromones are important accessories • sexes of differentiated species • differences allow for a combination of genetic material between two individuals 65 Parts • • • • the external genitalia (penis and vulva) the gamete producing gonads (testicles and ovaries) communicable sexually transmitted diseases vertebrate animals have generally similar reproductive systems consisting of gonads, ducts, and openings • diversity of physical adaptations and reproductive strategies in every group of vertebrates 66 Female Reproductive System 67 Male Reproductive System 68 Human Male Genitalia 1. Testicles 2. Epididymis 3. Corpus cavernosa 4. Foreskin 5. Frenulum 6. Urethral opening 7. Glans penis 8. Corpus spongiosum 9. Penis 10. Scrotum 69 Female Genitalia 1. 2. 3. 4. 5. Pubic hair (shaved) Clitoral hood Clitoris Labia majora Labia minora (enclosing the Vaginal Opening) 6. Perineum 70 Diseases • 1) genetic or congenital abnormalities • 2) cancers • 3) infections which are often sexually transmitted diseases • 4) functional problems cause by environmental factors, physical damage, psychological issues, autoimmune disorders, or other causes – sexual dysfunction – infertility 71 Examples of congenial abnormalities • Kallmann syndrome - Genetic disorder causing decreased functioning of the sex hormone-producing glands caused by a deficiency of a hormone. • Cryptorchidism - Absence of one or both testes from the scrotum. • Androgen insensitivity syndrome - A genetic disorder causing people who are genetically male (i.e. XY chromosome pair) to develop sexually as a female due to an inability to utilize androgen. • Intersexuality - A person who has genitalia or/and other sexual traits which are not clearly male or female. 72 Cancer • • • • • • Prostate cancer - Cancer of the prostate gland Breast cancer - Cancer of the mammary gland Ovarian cancer - Cancer of the ovary Penile cancer - Cancer of penis Uterine cancer - Cancer of the uterus Testicular cancer - Cancer of the testicals 73 Infections • HIV - Infection by the retrovirus known as human immunodeficiency virus. • Genital warts - Sexually transmitted infection caused by some sub-types of human papillomavirus (HPV). • Herpes simplex - Sexually transmitted infection caused by a virus called herpes simplex virus (HSV) type 2 • Gonorrhea - Common sexually transmitted disease caused by the Gram-negative bacterium Neisseria gonorrheae • Yeast infection - Infection of the vagina by any species of the fungus genus Candida. 74 Infections • Pelvic inflammatory disease - Painful infection of the female uterus, fallopian tubes, and/or ovaries with associated scar formation and adhesions to nearby tissues and organs. • Syphilis - Sexually transmitted infection caused by the bacterium Treponema pallidum. • Pubic lice - Infection of the pubic hair by crab lice, Phthirius pubis. • Trichomoniasis - Sexually transmitted infection by the single-celled protozoan parasite Trichomonas vaginalis. 75 Functional Problems • Impotence - The inability of a male to produce or maintain an erection. • Hypogonadism - A lack of function of the gonads, in regards to either hormones or gamete production. • Ectopic pregnancy - When a fertilized ovum is implanted in any tissue other than the uterine wall. • Inhibited sexual desire - A low level of sexual desire and interest. • Female sexual arousal disorder - A condition of decreased, insufficient, or absent lubrication in females during sexual activity • Premature ejaculation - A lack of voluntary control over ejaculation. 76 Mammals • most mammalian males have a penis which is stored internally until erect, and most have a penis bone or baculum • have descended and undescended (elephant) testicles found within a scrotum and ventral body wall respectively 77 Mammals • marsupials have two vaginae and two prolonged penis • - develop their offspring in an external pouch containing teats to which their newborn young attach themselves for post uterine development • - have a unique prepenial scrotum • uterus and vagina are unique to mammals with no homologue in birds, reptiles, amphibians, or fish • - cloaca is a shared exit-hole for gametes, urine, and feces 78 Mammals • • • • monotremes (i.e. platypus and echidnas) - a group of egg-laying mammals - lack a uterus and vagina - have a reproductive system resembling that of a reptile 79 Reptiles • • • • • • almost all sexually dimorphic exhibit internal fertilization through the cloaca (some) lay eggs (others) are viviparous (animals that deliver live young) reproductive organs are found within the cloaca (most male) have retracted or inverted copulatory organs and stored inside the body • in turtles and crocodilians, the male has a single median penis-like organ, while male snakes and lizards each possess a pair of penis-like organs 80 Amphibians • (most) exhibit external fertilization of eggs, within the water • (some) caecilians have internal fertilization • all have paired, internal gonads, connected by ducts to the cloaca 81 Fish • (most) oviparous and exhibit external fertilization • females use their cloaca to release a large quantities their gametes, called spawn, into the water and one or more males release "milt", a white fluid containing many sperm over the unfertilized eggs • other species of fish are oviparous and have internal fertilization aided by pelvic or anal fins that are modified into an intromittent organ analogous to the human penis 82 Fish • a small portion of fish species are either viviparous or ovoviviparous, and are collectively known as livebearers • fish gonads are typically pairs of either ovaries or testes • most fish are sexually dimorphic but some species are hermaphroditic or unisexual 83 Invertebrates • invertebrates have an extremely diverse array of reproductive systems, the only commonality may be that they all lay eggs • aside from cephalopods, and arthropods, nearly all other invertebrates are hermaphroditic and exhibit external fertilization 84 http://www.infovisual.info/03/038_en.html 85 Parts and Functions • Nervous system: set of nerves, ganglions and nervous centers that receivesensorysignal. • Commandsand coordinatesvitalfunctions. • Brachialplexus:networkofnervesof the arm. • Intercostalnerve: cordconductingnerveimpulsesbetweenthe ribs. • Radial nerve: cord conducting nerve impulses in the area of the radius. • Median nerve: main cord conducting nerve impulses in the upper limb. • Ulnar nerve: cord conducting nerve impulses in the area of the elbow. • Lumbarplexus:networkofnervesof the lowerback. 86 Parts and Functions • Sciatic nerve: cord conducting nerve impulses in the area of the thigh and lower leg. • Common peroneal nerve: cord conducting nerve impulses along the inside of the lower leg. • Superficial peroneal nerve: cord conducting nerve impulses of the muscles and skin of the leg. • Digital nerve: cord conducting nerve impulses of the fingers. • Sacral plexus: network of nerves of the sacrum. • Spinal cord: substance belonging to the nervous system, found in the holes of the vertebrae. Cerebellum: nervous centre situated under the brain. • Cerebrum: seat of the mental capacities. 87 Vertebrates: Worms • Planaria, a type of flatworm, have dual nerve cords running along the length of the body and merging at the tail and the mouth • nerve cords are connected by transverse nerves like the rungs of a ladder • transverse nerves help coordinate the two sides of the animal • Two large ganglia at the head end function similar to a simple brain • Photoreceptors provide sensory information on light and dark 88 Caenorhabditis elegans • The nervous system has been mapped out to the cellular level • Every neuron and its cellular lineage and most, if not all, of the neural connections are known • the nervous system is sexually dimorphic • the nervous systems of the two sexes, males and hermaphrodites, have different numbers of neurons and groups of neurons that perform sex-specific functions • males have exactly 383 neurons, while hermaphrodites have exactly 302 neurons 89 90 Arthropoda • have a nervous system made up of a series of ganglia • connected by a ventral nerve cord made up of two parallel connectives running along the length of the belly • each body segment has one ganglion on each side • though some ganglia are fused to form the brain and other large ganglia 91 Arthropoda • head segment contains the brain, also known as the supraesophageal ganglion • In the insect nervous system, the brain is anatomically divided into the protocerebrum, deutocerebrum, and tritocerebrum • behind the brain is the subesophageal ganglion, which is composed of three pairs of fused ganglia • controls the mouthparts, the salivary glands and certain muscles • have well-developed sensory organs, including compound eyes for vision and antennae for olfaction and pheromone sensation • sensory information from these organs is processed by the brain 92 93 Circulatory System • an organ system that moves nutrients, gases, and wastes to and from cells, helps fight diseases, and helps stabilize body temperature and pH to maintain homeostasis • as a blood distribution network • composed of the cardiovascular system, which distributes blood, and the lymphatic system, which distributes lymph • humans and other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system • most primitive animal lack circulatory systems 94 Circulatory System • main components of the human circulatory system are the heart, the blood,andthe bloodvessels • includes:the pulmonarycirculation • a "loop"throughthe lungs wherebloodisoxygenated • systemiccirculation • a "loop"throughthe restof the bodyto provideoxygenatedblood • average adult contains roughly 4.7 to 5.7 liters of blood, which consists ofplasma,red bloodcells, whitebloodcells,and platelets • 2 types of fluids move through the circulatory system: blood and lymph • blood,heart,and bloodvesselsform the cardiovascularsystem • lymph, lymph nodes,and lymph vesselsformthe lymphaticsystem 95 CS of other Vertebrates • closed, just as in humans • In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues • known as single cycle circulation • heart of fish is only a single pump (consisting of two chambers) 96 Amphibians and Reptiles • a double circulatory system • amphibians have a three-chambered heart • In reptiles, the ventricular septum of the heart is incomplete and the pulmonary artery is equipped with a sphincter muscle • allows a second possible route of blood flow • divert blood flow through the incomplete ventricular septum into the left ventricle and out through the aorta • the blood flows from the capillaries to the heart and back to the capillaries instead of to the lungs 97 Other Vertebrates • birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers • the four-chambered heart of birds evolved independently from that of mamma 98 Digestive System 99 Digestive System • Almost all animals have a tube-type digestive system in which food enters the mouth, passes through a long tube, and exits as feces (poop) through the anus • The smooth muscle in the walls of the tube-shaped digestive organs rhythmically and efficiently moves the food through the system, where it is broken down into tiny absorbable atoms and molecules 100 Digestive System • during the process of absorption, nutrients from the food (including carbohydrates, proteins, fats, vitamins, and minerals) pass through channels in the intestinal wall and into the bloodstream • blood works to distribute these nutrients to the rest of the body • waste parts of food that the body can't use are passed out of the body as feces 101 How Digestion Works • digestive system is made up of the alimentary canal (also called the digestive tract) and the other abdominal organs that play a part in digestion, such as the liver and pancreas • the long tube of organs — including the esophagus, stomach, and intestines — that runs from the mouth to the anus • adult's digestive tract is about 30 feet (about 9 meters) long 102 Digestion begins in the… • mouth beforefoodreaches the stomach • salivary glands, which are located under the tongue and near the lowerjaw,beginproducingsaliva • flow of saliva is set in motion by a brain reflex that's triggered when we sense foodor thinkabouteating • in response to sensory stimulation, the brain sends impulses through the nerves that control the salivary glands, telling them to prepare for a meal • as the teeth tear and chop the food, saliva moistens it for easy swallowing • a digestive enzyme called amylase, which is found in saliva, starts to break down some of the carbohydrates (starches and sugars) in the foodevenbeforeit leavesthe mouth 103 • swallowing, which is accomplished by muscle movements in the tongue and mouth, moves the food into the throat, or pharynx • the pharynx, a passageway for food and air, is about 5 inches (12.7 centimeters) long • a flexible flap of tissue called the epiglottis reflexively closes over the windpipe when we swallow to prevent choking • from the throat, food travels down a muscular tube in the chest called the esophagus • waves of muscle contractions called peristalsis force food down through the esophagus to the stomach • a person normally isn't aware of the movements of the esophagus, stomach, and intestine that take place as food passes through the digestive tract 104 • At the end of the esophagus, a muscular ring or valve called a sphincter allows food to enter the stomach and then squeezes shut tokeep foodor fluid from flowingback up intothe esophagus • The stomach muscles churn and mix the food with acids and enzymes, breakingit intomuch smaller,digestiblepieces • An acidic environment is needed for the digestion that takes place in the stomach • Glands in the stomach lining produce about 3 quarts (2.8 liters) of these digestivejuiceseach day. • Most substances in the food we eat need further digestion and must travelintothe intestinebeforebeing absorbed • When it's empty, an adult's stomach has a volume of one fifth of a cup (1.6 fluid ounces), but it can expand to hold more than 8 cups (64 fluid ounces)of foodaftera largemeal. 105 • By the time food is ready to leave the stomach, it has been processed into a thick liquid called chyme • A walnut-sized muscular valve at the outlet of the stomach called the pylorus keeps chyme in the stomach until it reaches the right consistency to pass into the small intestine • Chyme is then squirted down into the small intestine, where digestion of food continues so the body can absorb the nutrients into the bloodstream 106 Parts and Functions Lymphatic System What is a lymphatic system? • a network of conduits that carry a clear fluid called lymph • includes the lymphoid tissue and lymphatic vessels through which the lymph travels in a one-way system in which lymph flows only toward the heart • lymphoid tissue is found in the lymph nodes, and in the lymphoid follicles associated with the digestive system such as the tonsils • includes all the structures dedicated to the circulation and production of lymphocytes, which includes the spleen, thymus, bone marrow and the lymphoid tissue associated with the digestive system • described independently by Olaus Rudbeck and Thomas Bartholin Five Interrelated Functions • it is responsible for the removal of interstitial fluid from tissues • it absorbs and transports fatty acids and fats as chyle to the circulatory system and to Nicklas cells • it transports immune cells to and from the lymph nodes in to the sheppardian part of the bone • transports antigen-presenting cells (APCs), such as dendritic cells, to the lymph nodes where an immune response is stimulated • carries lymphocytes from the efferent lymphatics exiting the lymph nodes Organization • divided into the conducting system • the lymphoid tissue • conducting system carries the lymph and consists of tubular vessels that include the lymph capillaries, the lymph vessels, and the right and left thoracic ducts • lymphoid tissue is involved in immune responses and consists of lymphocytes and other white blood cells • - regions of the lymphoid tissue that are densely packed with lymphocytes are known as lymphoid follicles Organization • lymphoid tissue can either be • structurally well organized as lymph nodes or • may consist of loosely organized lymphoid follicles known as the mucosa-associated lymphoid tissue (MALT) 111 Lymphoid Tissue • concerned with immune functions in defending the body against the infections and spread of tumors • consists of connective tissue with various types of white blood cells enmeshed in it, most numerous being the lymphocytes Lymphoid Tissue • Primary (central) lymphoid tissues serve to generate mature virgin lymphocytes from immature progenitor cells • thymus and the bone marrow constitute the primary lymphoid tissues involved in the production and early selection of lymphocytes Secondary (peripheral) lymphoid tissues • provide a place where lymphocytes can talk to each other • - an environment for antigen focusing, where lymphocytes can 'study' an antigen and sharpen up the immune response by clonal expansion and affinity maturation • provide a home for lymphocytes, where they can be available when they are needed • provides the environment for the foreign or altered native molecules (antigens) to interact with the lymphocytes 114 Tertiary lymphoid tissue • contains few lymphocytes • assumes an immune role only when challenged with antigens that result in inflammation • achieves by importing the lymphocytes from blood and lymph 115 Lymph Node • an organized collection of lymphoid tissue, • located at intervals along the lymphatic system • substance of a lymph node consists of lymphoid follicles in the outer portion called the "cortex", which contains the lymphoid follicles, and an inner portion called "medulla", which is surrounded by the cortex on all sides except for a portion known as the "hilum“ • arteries and veins supplying the lymph node with blood enter and exit through the hilum. • lymph follicles are a dense collection of lymphocytes, the number, size and configuration of which change in accordance with the functional state of the lymph node Lymph nodes • particularly numerous in the mediastinum in the chest, neck, pelvis, axilla (armpit), inguinal (groin) region and in association with the blood vessels of the intestines 117 Lymphatics • based on that of blood vessels • an inner lining of single flattened cells composed of a type of epithelium is called endothelium, and the cells are called endothelial cells • mechanically transport fluid and since the basement membrane on which it rests is discontinuous; it leaks easily • next layer is that of smooth muscles that are arranged in a circular fashion around the endothelium, which by shortening (contracting) or relaxing alter the diameter (caliber) of the lumen • outermost layer is the adventitia that consists of fibrous tissue Lymphatics • whole system consists of two types of channels—the initial lymphatics, the prelymphatics or lymph capillaries that specialize in collection of the lymph from the ISF, and the larger lymph vessels that propel the lymph forward • not closed and has no central pump • movement occurs despite low pressure due to peristalsis, valves, and compression Rhythmic Contraction • may also help draw fluid into the smallest lymphatic vessels, capillaries • if tissue fluid builds up the tissue will swell; this is called edema • fluid is then transported to progressively larger lymphatic vessels culminating in the right lymphatic duct (for lymph from the right upper body) and the thoracic duct (for the rest of the body) Rhythmic Contraction • both ducts drain into the circulatory system at the right and left subclavian veins • system collaborates with white blood cells in lymph nodes to protect the body from being infected by cancer cells, fungi, viruses or bacteria • known as a secondary circulatory system Lymph Vessels • lymph capillaries drain the lymph to larger contractile lymphatics, which have valves as well as smooth muscle walls • as the collecting lymph vessel accumulates lymph from more and more lymph capillaries in its course, it becomes larger and is called the afferent lymph vessel as it enters a lymph node. • the functional unit of a lymph vessel is known as a lymphangion, which is the segment between two valves Disease of the Lymphatic System • Lymphedema is the swelling caused by the accumulation of lymph fluid Stages of lymphedema • Stage 1: Pressing the swollen limb leaves a pit that takes a while to fill back in. Because there is little fibrosis (hardening) it is often reversible. Elevation reduces swelling. • Stage 2: Pressure does not leave a pit. Elevation does not help. If left untreated, the limb becomes fibrotic. • Stage 3: This stage of lymphedema is often called elephantiasis. It is generally only in the legs after lymphedema that has gone long untreated. While treatment can help a little, it is not reversible. Common causes of swollen lymph nodes • infections, infectious mononucleosis, and cancer • In elephantiasis, infection of the lymphatic vessels cause a thickening of the skin and enlargement of underlying tissues, especially in the legs and genitals • commonly caused by a parasitic disease known as lymphatic filariasis • Lymphangiosarcoma is a malignant soft tissue tumor (soft tissue sarcoma) • lymphangioma is a benign tumor occurring frequently in association with Turner syndrome • Lymphangioleiomyomatosis is a benign tumor of the smooth muscles of the lymphatics that occurs in the lungs