Skeleton lecture - Skeletal notes PDF

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Skeletal notes...

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Jennifer lecture 2/3/16 Vertebrate endoskeleton functions Body support Protection-internal organs Movement-skeletal muscles attach to bone Storage –ca+ and po4Blood cell formation Storage of energy sources-lipds Skeletal systems Types Hydrostatic – fluid filled body compartment—muscle contracts on compartment, causing fluid to move within compartment Muscular hydrostat—tissue fluid (tongue)- tissues maintain constant volume Exoskeleton—secreted by and covers epithelium- muscle attached to it, contraction causes skeleton to move (crabs leg) Endoskeleton—covered by another tissue, muscle attached to it, contraction causes skeleton to move Types Hydrostatic—invetebrates and some vertebrates Muscular hydrostat—invertebrates and vertebrates Exoskeleton-invertebrates Endoskeleton-chordates (notochord or bone) and echinoderms (ossicles) Hydrostatic Skeleton Fluid filled area upon which muscles contract Pseudocoelom nematode Female ascaris Hydrostatic skeleton: Annelids Septa between gut and body wall divide the fluid filled coelom Muscles (circular and longitudinal) contract on coelom Hydrostatic skeleton of each segment can function largely independent from others Hydrostatic skeleton: Cnidarians Gastrovascular cavity

Two body layers work in anatognistic fashion on fluid filled gastrovascular cavity Have contractile proteins in base of cells Epidermal contraction (outer later) causes shortening Endodermal contraction (inner) layer causes lengthening Hydrostatic skeleton: Platyhelimnthes Gastrovascular cavity Muscular Hydrostatic Skeleton—working against tissue Mammalian and reptilian tongues Spiders legs Elephants trunk Echinoderms-coelom and tube feet Octopus arms Exoskeletons – have to be secreted by and covers epithelium Composition: calcium carbonate or chitin Found in invertebrates Cnidarians: anthozoa (hard corals) Mollusks: shell Arthropods Cuticle containing chitin. thin flexible joints Must molt (ecdysis) [ Ecdysozoa] Endoskeletons—covered by another tissue Examples: proiferans: spicules in mesohyl Echinoderms—calcified spines and plates beneath epidermis Vertebrates—bone or cartilage or combination Vertebrate Endoskeleton Mainly bone ( ossified) Chondrichthyes-cartilage Tetrapod skeleton (birds, amphibians, reptiles, mammals) Axial skeleton – Central axis, head spine pelvis ribcage Appendicular skeleton—limb bones and connections. Appendicular. If you lose it you don’t automatically die Divisions- Pectoral (shoulder) girdle. Pelvic (hip) girdle

Dense vs Spongy Bone Dense—structure: osteon system Compact bone Outer ‘hard” bone Encloses spongy bone and marrow cavity Muscles attach to it Spongy Bone Location—surrounded by dense bone. Ends of long bones. Center of flat ones space filled with marrow Name: also called trabecular bone Structure: trabeculae Function: all blood cells formed here (red bone marrow, yellow bone marrow is where all fat is stored) Bones and Blood Cell Production Marrow—soft tissue in marrow cavity and between trabeculae (yellow typically in shaft of long bones) Yellow—consists fatty connective tissue shaft of long bones Red—produces blood cells. Children almost every bone cavity they have is producing red blood cells. Adults more limited Classification of Bones: Long bones (humerus) Short bone (trapezoid, wrist bone) Flat bone (sternum) Irregular bone (vertebra) Sesamoid bone (patella) Long bone Structure: Periosteum—connective tissue membrane Covers bone: inside and outside surfaces. Attachment site for tendons and ligaments Epiphysis: end of long bone. Articulation site Diaphysis: shaft

Metaphysis: between epiphysis and diaphysis (when you’re a kid it’s called the epiphyseal plate) Epiphyseal plate: growth plate Epiphyseal line: growth stops, mature Dense bone Osteon System Osteon system: Osteons: interlocking structural units Osetocytes: mature bone cells Lacunae: small cavities (osteocytes here) Lamellae: connective circles ( collogen is usually layed down in alternating clockwise and counter clockwise pattern) Canaliculi: small channel between lacunae Haversian canal: central, runs lengthwise with blood vessel. (really important ) Bone formation Fetal bone development Endochondral bone development (most common): long bones develop from cartilage templates Fetal bone development Intramembranous bone development: bones without synovial joints develop from a noncartilage, connective tissue scaffold (skull, all the sutures that grow together aren’t synovial joints) Joints (articulations) Location: junctions between two or more bones Function: allow flexibility and movement between most bones Bone surfaces in contact are covered by articular cartilage (white cartilage layer at very end of bone- you don’t want bone rubbing on bone) anywhere bones come into contact with each other is an articulation 3 types of articulations synovial—encapsulated, fluid filled reinforced with ligaments (shoulder blade) freely moveable Fibrous—bones joined by fibrous connective tissue. Only slightly or immoveable Cartilaginous- cartilage. Slightly moveable. Synovial joints are freely moveable and can move in several planes. Elbow is a synovial joint even though it only goes one way. Ball and socket. Wrist.

Fibrous joints: synarthrosis: immoveable – sutures Amphiarthrosis: slightly moveable. Ligament connection . (inbetween tibia and fibia) Cartilaginous joints: amphiarthrosis: slightly moveable (pubic synthase) Between ribs and sternum. There for absorbing impact Ways you can move; look at chart Rest of other lecture: Connective tissue vascularity: Most well vascularized Cartilage-avascular Dense- poorly Loose Connective tissue Function: cushion and support Fibers: elastic and collagen. Runs all directions. In semifluid matric Location: subcutaneous layer attaching skin to muscle and underlying structures (eg; nerves, blood vessels) Thin filling between body parts. Serves as reservoir for fluid and salts. Be able to identify , what its made of, and where it’s located Dense Connective Tissue: Regular Description- strong less flexible than loose connective tissue Fibers-mainly collagen Regular: Purpose-strength Fibers-closely packed fibers Location: tendons: mostly collagen Ligaments: elastic and collagen Muscles; fascia separating muscles

Dense connective tissue: irregular Purpose: strength against force in multiple directions Fibers: mainly collagen. No uniform direction Location: dermis of skin. Joint capsules Elastic Connective Tissue Structure: mainly bundles of parallel elastic fibers Function: allows structures to return to their original size and shape following expansion (distension) Location: lungs, walls of large arteries Reticular Connective Tissue Fibers: interlacing, very thin collagen Function: supporting internal framework in many organs Location: includes liver, spleen, and lymph nodes Note: fibers are not in parallel but “fish net” or “scaffolding” Example of spleen Adipose Connective Tissue Cell: adipocytes Function cushion, support, insulate, energy store Location: subcutaneous layer and associated with many organs Structure: very distinctive Circle or star shaped. Because fat doesn’t like to be around non-fat so all hydrophobic fat cells want to get together so they stay inside certain areas. Cartilage Cells: Chondrocytes Structure: chondrocytes lie in small cavities (lacunae) in hard matrix with collagen fibers Function: structural support. Forms supporting skeleton in embryonic stages of all vertebrates (notochord) Lacks nerves, lymph vessels, and blood vessels within tissue. Three types, but they all share the above information in common Hyaline Cartilage Fibers: mainly collagen Function: support and stiffness. Reduces friction. Resists compression

Location: ends of long bones. Rib cage Microscopic characteristic: chondrocytes in clusters Elastic Cartilage Fibers: more elastic than collagen Function: support and flexibility Location: pinna, epiglottis, parts of larynx Microscopic characteristic: chondrocytes mainly in groups of two Fibrocartilage Fibers: thicker collagen fibers than hyaline Function: strength, rsists compression, absorbs shock Location: intervertebral discs, pubic symphysis, knee joint Microscopic characteristic: Some areas chondrocytes look like they are in a line Other connective tissues to be discussed later Bone—discussed with skeletal system Lymph—liquid connective tissue, discussed with immunology Blood-liquid connective tossieu, discussed with circulation 39.2 Regulating the internal environment Homeostatis (variation) rather than homeostasis (constant_ Dynamic equilibrium in which conditions are maintained within certain limits (steady state) by homeostatic mechanisms Stressor (environmental change) initiates a response Receptor (sensor) detects the change Integrator: compares new and steady state information Effector: responds to signals from integrator Many homeostatic mechanisms involved feedback systems. (can be negative or positive, most of ours are based on negative feedback) Conformers and regulators Conformers: energetically more economical Alter internal environment to conform with environment (temperature, solute composition) Marine invertebrates Regulators: ATP requiring

Maintain relatively constant internal conditions despite changes in the outside environment Some organisms like fish, use a combination regulate some osmotic composition but conform to temp. (ph different in blood than it is in the ocean, but their temperature is the same as the ocean) Negative Feedback Most common. Go against the stressor. Stimulus causes change. Response: a sensor senses change and communicates with an integrator that activates mechanisms to move variable in opposite direction (back toward homeostatic values) Stressor causes deviation from set point. Sensor detects change from set point. Sensor signals integrator (control center). Integrator activates effectors (homeostatic mechanisms). Normal condition (set point) restored. Stressor pushes it away and we’re trying to do the opposite of the stressor. Positive Feedback Trying to make stress response greater. Amplify the stressor. Stimulus sets off a response that intensifies (rather than reverses) the changing condition. Amplification in direction of stimulus accelerates process until some final event. Some beneficial, but do not maintain contribute to homeostasis Examples: Childbirth, blood clotting, severe blood loss. Propagation of nerve impulse by sodium channels Stressor: injury. Hemorrhage (blood loss). Blood pressure decreases. Less blood circulates to heart. Cardiac output decreases (heart pumps less blood) 39.3 regulating Body temperature Thermoregulation—process of maintaining body temperatures within certain limits Ectotherms—rely on external heat to warm body and stimulate metabolism use behavior to alter body heat or move environments. (reptile example) Endotherms: maintain internal body heat by regulating metabolism . high cost since also maintain heat during periods of inactivity. (us example) we have the advatange of being able to go to different areas, but it costs us a lot of ATP to do this

Adjusting to Temperature Changes Acclimatization Animals adjust to season changes. Ie; thickening of dogs coat in winter .thinning in spring Torpor – short term state in which metabolic rate decreases Ie; hibernation inactivity during cold periods. Estivation inactively when lack of food or water. Saves energy use to maintain a high body temperature. (hibernation example, falling into lake and surviving example_)...