BIO 1200 Exam 2 Molloy

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Gonads
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Terms in this set (81)
Gonads
Reproductive organs that produce gametes and hormones
Perineal structures
external genitalia
Testis
Gonad producing spermatozoa or sperm
Male reproductive tract
Transports semen (sperm with secretions of accessory glands)
Pathway of sperm
Testes --> Epididymis --> Ductus deferens --> Ejaculatory duct --> Seminal vesicle --> Urethra --> Prostate gland --> Bulbo-urethral glands
Seminal glands
secrete fluid forming bulk semen volume
Urethra
conducts semen to exterior
Penis
deposits sperm into vagina
Scrotum
surrounds testes
Seminiferous tubules
• Coiled tubules within lobules (total length ~1/2 mile/testis)
• Site of sperm production
Efferent ductuleslead from rete testis to epididymisEpididymis• Consists of tightly coiled ductus epididymis • Stereocilia are microvilli that reabsorb degenerated sperm • Site of sperm maturation - acquire motility and ability to fertilizeDuctus deferens• Passes through inguinal canal as part of spermatic cord • Transports and stores (for several months) spermatozoa conducts sperm from epididymis to prostate glandAmpulladistal portion posterior side of bladderEjaculatory ductfrom ductus deferens to urethraSeminal glands (also called seminal vesicles)• Contribute ~60% of semen • Secretion ejected by smooth muscle lining gland • Stimulates flagellum movement in spermatozoa • First step of capacitationProstate gland• Contributes 20%-30% of semen • Contains seminal plasmin (antibiotic for male tract) secretes fluid and enzymesBulbo-urethral glandsSecrete alkaline mucus for lubrication and pH bufferBenign prostatic hypertrophy (BPH) (Prostate disorder)• Typically occurs in men over age 50 • Increase in size occurs with decrease in testosterone • Also some increases in estrogen • Can constrict prostatic urethra and affect urinationProstate cancer (Prostate disorder)• 2nd most common cancer • Blood tests screen for prostate-specific antigen (PSA) • Treatment is radiation or surgical removal of prostate (prostatectomy)Uterine tubesdeliver oocyte or embryo to uterusUterussite of embryonic and fetal development Provides mechanical protection, nutritional support, and waste removal for embryo (weeks 1-8) and fetus (>8 weeks)Vaginasite of sperm despositionClitoriserectile tissue producing pleasurable sensationsLabiacontain glands to lubricate vaginaMammary glandsproduce nourishing milk for infantUterine tubeconducts oocytes from ovary to uterusInfundibulumexpanded funnel near ovaryPerimetrium (uterus layer) (OUTER)Incomplete serosa continuous with peritoneal liningMyometrium (uterus layer) (MIDDLE)Smooth muscle layer providing force for childbirthEndometrium (uterus layer) (INNER)Inner epithelial lining whose character changes monthlyFertilization• Fusion of two haploid (23 chromosomes) gametes • Produces zygote (46 chromosomes) • Occurs generally in the uterine tube ampulla or isthmus• ~24 hours after ovulation • While ~200 million spermatozoa are commonly deposited in vagina: • ~10,000 enter correct uterine tube • <100 reach isthmus • Only 1 sperm fertilizes the egg but others help it to gain access to oocyte interiorCleavage• Division of zygote cytoplasm into numerous blastomeres • Pre-embryo = group of blastomeres created by cleavage • Lasts ~7 days • Movement down uterine tubes toward uterus is occurring during this time • After 3 days, pre-embryo is solid ball of cells (morula) • After 5 days, blastomere becomes hollow ball of cells (blastocyst) with interior cavity (blastocoele)Cleavage and ImplantationImplantationImplantation• Day 6: Blastocyst growth • Proximity to uterine gland secretions increases cell division rate of blastocyst • Day 7: Implantation • Attachment of blastocyst to endometrium • Blastocyst forms • Outer layer of cells (trophoblast) that provide nutrients to developing embryo • Inner mass cells (will form embryo)Allantois• Begins as outpocket of endoderm near yolk sac base • Endodermal and mesodermal cells form stalk attaching to blastocyst wall • Later allantois base will form urinary bladderChorion• Mesoderm and trophoblast near allantois • Chorionic villi invade endometrium and receive nutrients • Placenta develops and becomes primary embryo support • Oxygen and nutrients exchanged for carbon dioxide and wastesPaired umbilical arteriesBring deoxygenated blood with fetal wastes to placentaSingle umbilical veinReturns oxygenated blood with nutrients from placenta to fetusIntegumentary system• Most accessible organ system • Can be referred to as skin or integument • 16% of total body weight • 1.5-2 m2 in area • Body's first line of defense against environment • Has two major components 1. Cutaneous membrane 2. Accessory structuresEpidermisStratified squamous epithelium • Dominated by the most abundant epithelial cells (keratinocytes) • Continuously produced in the deepest layers and shed at exposed surface • Form several layers or strata • Deep layers form epidermal ridges • Bind to dermal papilla (papilla, nipple-shaped mound) of dermis • Most of body covered with four strata (thin skin) • Palms of hands and soles of feet have five strata (thick skin) • Merkel cells in deep layers • Sensory neuron extensions for pain and temperatureDermis• Papillary layer (areolar connective tissue) Papillary layer • Named for dermal papillae • Consists of areolar tissue • Contains: • Capillaries • Lymphatic capillaries • Sensory neurons • Reticular layer (dense irregular connective tissue) • Meshwork of dense irregular connective tissue • Collagen fibers (extend into papillary layer and hypodermis) • Elastin fibers • Contains similar structures as papillary layer but also sweat glands and hair folliclesHypodermis• Not part of integument • Separates integument from deep fascia • Separates skin from deeper structures • Stabilizes skin to underlying tissues • Allows independent movement • Dominated by adipose tissueAccessory structures• Hair shaft and follicle • Sweat gland • Tactile and lamellated corpuscles • Sebaceous gland • Arrector pili muscle • Nerve fibersCutaneous plexusnetwork of blood vesselsEpidermis layers• "Come, Let's Get Sun Burned": · From superficial to deep: Corneum Lucidum Granulosum Spinosum Basale [Germinativum]Stratum corneum (Layer of epidermis)• Outermost protective layer • 15-30 layers of keratinized cells (filled with keratin) • All dead cells attached with desmosomes • Remain in stratum corneum ~2 weeks before shedStratum lucidum ("clear layer") (Layer of epidermis)• Separates stratum corneum from underlying layers • Flattened dead cells filled with keratin and keratohyalin • Absent in thin skinStratum granulosum ("grainy layer") (Layer of epidermis)• 3-5 layers of keratinocytes • Living cells that have stopped dividing and started making keratin and keratohyalin • As protein fibers develop, membranes become less permeableStratum spinosum ("spiny layer") (layer of epidermis)• 8-10 layers of live keratinocytes bound by desmosomes • Cells look spiny in histological sections • Dendritic cells (immune system cells) also found here • Defend against pathogens and superficial cancersStratum basale (layer of epidermis)• Basal cells (stem cells) attached to basal lamina with hemidesmosomes • Actively dividing to replace cells lost on superficial layers • Merkel cells (touch receptors) also found hereMelanocytes• Manufacture melanin from amino acid tyrosine • Package melanin in vesicles (melanosomes) • Transferred to keratinocytes and maintained until fusion with lysosomes • Occurs in stratum basale and spinosum in light-skinned people • Transfer of larger melanosomes into stratum granulosum as well for dark-skinned peopleBasal cell carcinoma (skin cancer)• Most common skin cancer • Originates in stratum basale in response to UV radiation • Virtually no metastasis and most people surviveMalignant melanoma (skin cancer)• Cancerous melanocytes • Commonly metastasize through lymphatic system • Detected early, 5-year survival is 99% • Not detected until metastasis, 5-year survival is 14%Lines of cleavage• Formed by arrangement of collagen and elastin fibers in the skin • Clinically significant for surgery and wound healing • Parallel to cleavage: better healing and less scarring • Perpendicular to cleavage: remain open and more scarringArrector pili muscle• Smooth muscle that pulls on follicle causing hair to stand erect (goosebumps)Sebaceous glands (oil glands)• Holocrine glands that discharge an oily lipid secretion • Simple branched alveolar glands that secrete onto one hair follicleApocrine sweat glands• Limited distribution (axillae, groin, nipples) • Produce viscous secretion with complex composition • Possible function in olfactory communication • Strongly influenced by hormones • Include ceruminous glands and mammary glandsMerocrine sweat glands• Found in most areas of skin • Produce watery secretions with electrolytes • Controlled primarily by nervous system • Important in thermoregulation and excretion • Some antibacterial actionFunctions of the skeletal system• Support (support for body, attachment for soft tissues) • Storage of minerals (calcium and phosphate) • Calcium most abundant mineral in body (~2-4 lb) • 98% stored in bones • Blood cell production (all formed elements of blood) • Protection (delicate tissues and organs surrounded by bone) • Leverage (act as levers with skeletal muscles to move body)Epiphysis (expanded area at each end of the bone)• Consists largely of spongy bone (cancellous or trabecular bone) • Network of struts and plates • Resists forces from various directions and directs body weight to diaphysis and jointsOuter covering of compact bone• Strong, organized bone (cortical bone)Articular cartilage• Covers portions of epiphysis that form articulations • Avascular, so relies on diffusion from synovial fluid for nutrient delivery and waste eliminationMetaphysis(connects epiphysis to shaft)Diaphysisshaftmedullary cavity (marrow cavity)contains bone marrowPeriosteum1. Isolate bone from surrounding tissues 2. Route for blood and nervous supply 3. Actively participate in bone growth and repair • Smaller blood vessels (supply superficial osteons) • Lymphatic vessels (collect lymph from bone and osteons) •Sensory nerves (innervate diaphysis, medullary cavity, and epiphyses)Nutrient artery/vein (commonly one each/bone)• Nutrient foramen (tunnel providing access to marrow cavity) • Also supplies osteons of compact bone with bloodMetaphyseal artery/vein• Carry blood to/from metaphysis • Connects to epiphyseal arteries/veinsOsteocytes• Mature bone cells that cannot divide • Most numerous bone cell type • Maintain protein and mineral content of adjacent matrix • Dissolve matrix to release minerals • Rebuild matrix to deposit mineral crystals • Occupy lacunae (pocket) • Separated by layers of matrix (lamellae) • Connected with canaliculiOsteoblasts• Produce new bony matrix (osteogenesis or ossification) • Begins with release of proteins and other organic components to produce unmineralized matrix (= osteoid) • Then assists in depositing calcium salts to convert osteoid to bone • Become osteocytes once surrounded by bony matrixOsteoprogenitor cells• Mesenchymal (stem) cells that produce cells that differentiate into osteoblasts • Important in fracture repair • Locations • Inner lining of periosteum • Lining endosteum in medullary cavity • Lining passageways containing blood vesselsOsteoclasts• Remove and remodel bone matrix • Giant cells with 50+ nuclei • Derived from same stem cells as macrophages • Release acids and proteolytic enzymes to dissolve matrix and release stored minerals • = Osteolysis (lysis, loosening)Appositional bone growth• Increases bone diameter of existing bones • Does not form original bones • Osteoprogenitor cells differentiate into osteoblasts that add bone matrix under periosteum • Adds successive layers of circumferential lamellae • Trapped osteoblasts become osteocytes • Deeper lamellae recycled and replaced by osteons • Osteoclasts remove matrix at inner surface to enlarge medullary cavityEndochondral ossification• Initial bone formation in embryo begins with cartilage • Replaced by bone through endochondral (endo-, inside + chondros, cartilage) ossification • Uses cartilage as small model • Bone grows in diameter and length • Diameter growth involves appositional bone depositionIntramembranous ossification• Begins as mesenchymal (stem) cells differentiate into osteoblasts within embryonic or fibrous connective tissue • Normally occurs in deeper layers of dermis • = Dermal bones (or membrane bones) • Examples: • Roofing bones of skull • Lower jaw • Collarbone • Sesamoid bones such as patellaBone composition• 67 percent inorganic components • 33 percent organic components (primarily collagen) • Bones contain 99 percent of the body's calciumMaintaining calcium levels• Intestines: Absorb calcium and phosphate under hormonal control • Bones: •Osteoblasts erode matrix and release calcium Osteoblasts use calcium to deposit new matrix Kidneys: Varying levels of calcium and phosphate loss in urine under hormonal controlParathyroid hormone (PTH)• Secreted from parathyroid glands • Responses • In bones: • Osteoclasts stimulated to erode matrix, releasing stored calcium • In intestines: • Calcitriol effects enhanced and calcium absorption increased • In kidneys: • Increased release of hormone calcitriol, stimulating calcium reabsorption in kidneysCalcitonin• Secreted from C cells in the thyroid gland • Responses • In bones: • Osteoclast activity inhibited; calcium deposited in bone matrix • In intestines: • Calcium absorption decreased with decreasing PTH and calcitriolTypes of fractures• Closed or simple (completely internal) • Only seen on x-rays • Open or compound (project through skin) • More dangerous due to: • Infection • Uncontrolled bleeding • Transverse • Break shaft across long axis • Spiral • Produced by twisting stresses • Spread along length of bone • Displaced • Produce new and abnormal bone arrangements • Nondisplaced retain normal alignment • Compression • In vertebrae subjected to extreme stresses • Greenstick • One side of shaft broken, one side bent • Generally occurs in children • Comminuted • Shatter affected area producing fragments • Epiphyseal • Where bone matrix is calcifying • A clean transverse fracture of this type heals well • If not monitored, breaks between epiphyseal plate and cartilage can stop growth at site • Pott • At ankle and affects both leg bones • Colles • Break in distal radius