Anatomy and Physiology - Week 6
Anatomy and Physiology - Week 6 BSC2085
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This 18 page Class Notes was uploaded by Hannah Hartman on Sunday October 16, 2016. The Class Notes belongs to BSC2085 at Florida State University taught by Dr. Yung Su in Fall 2016. Since its upload, it has received 4 views. For similar materials see Anatomy & Physiology 1 in biological science at Florida State University.
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Date Created: 10/16/16
Bone (Osseous) Tissue Bone tissue o Dense, supportive connective tissue o Contains specialized cells o Produces solid matrix of calcium salt deposits around collagen fibers Characteristics of bone tissue: o Dense matrix, containing: Deposits of alcium salts Osteocytes (bone cells) within cunae (chambers surrounded by the bone matrix) they are organized around blood vessels and connected to other osteocytes by gap junctions. o Canaliculi – small channels that connect lacunae to each other and to blood vessels of the central canal Form pathways for blood vessels for exchange of nutrients and wastes o Periosteum Covers outer surfaces of bones Consists of outer fibrous and inner cellular layers Bone matrix – composed of: o Minerals Twothirds of bone matrix is lcium phosphate , CA2(PO4)2 Reacts with alcium hydroxide , Ca(OH)2 to form crystals of hydroxyapatite, Ca10(PO4)6(OH)2 Hydroxyapatite incorporates other lcium salts (CaCO3) and ions (sodium, magnesium, fluoride) Matrix proteins Onethird of bone matrix is protein fibers (gen) o Bone matrix of calcium crystals and protein allow for bone to be strong and still somewhat flexible Bone cells – make up only 2 percent of bone mass: o Bone contains four types of cells Osteocytes: mature bone cell that maintains the bone matrix Live in acunae between layers lamellae of matrix Connected by cytoplasmic extensions through canaliculi in lamellae by gap junctions Do not divide Two major functions of osteocytes o To maintain protein and mineral content of the matrix o To help repair damaged bone Osteoblasts: immature bone cell that secretes osteoid, the organic component of bone matrix (osteogenesis) Osteoid – the matrix produced y osteoblasts, but not yet calcified by calcium salts to form bone When osteoblasts become surrounded by bone, they become osteocytes Osteoprogenitor cells: stem cell who’s divisions produce osteoblasts Mesenchymal stem cells that divide to produce osteoblasts Located in: o Endosteum – lines the medullary cavity and passageway for blood vessels found in the matrix of compact bone o The inner cellular layer of osteum Important in fracture repair Osteoclasts: multinucleated cells that secretes acids and enzymes to dissolve bone matrix Derived from stem cells that produce crophages o Do not develop from osteoprogenitor cells Secrete acids and proteindigesting enzymes o Dissolve bone matrix and release stored minerals (osteolysis/resportion) o Important in regulating calcium and phosphate concentrations in body fluids Homeostasis: o Bone building (by steoblasts) and bone recycling (by teoclasts must balance More breakdown than building, bones become weak Exercise, particularly weightbearing exercise, causes osteoblasts to build bone faster than osteoclasts can break down bone This can be a problem for astronauts Compact Bone and Spongy Bone o The structure of compact bone o Osteon is the basic unit of mature compact bone Osteocytes are arranged in ncentric lamellae around a central canal containing blood vessels o Perforating canals Perpendicular to the ntral canal Carry blood vessels into bone and marrow o Circumferential lamellae Lamellae wrapped around the long bone, encircling multiple osteons Binds osteons together o The structure of spongy bone o Does not have osteons o The matrix forms an open network of rabeculae bone fiber bundles o Trabeculae have o blood vessels, canaliculi open onto surface of trabeculae The space between trabeculae is filled with bone marrow o Which has blood vessels And supplies nutrients to eocytes Forms red blood cells o Yellow bone marrow – found in medullary cavity and in spongy bone of some bones Is yellow because it stores fat ose tissue) o Compact bone is covered with a membrane o Periosteum on the outside Covers all bones except parts enclosed in joint capsules Made up of an outer, fibrous layer and an inner, cellular layer Perforating (Sharpey’s) fibers: collagen fibers of the periosteum Connect with collagen fibers in bone and with fibers of joint capsules; attach tendons and ligaments Strengthens tendon and ligament attachment to bone Functions of eriosteum Isolates bone from surrounding tissues Provides a route for circulatory and nervous supply Participates in bone growth and repair o Endosteum on the inside An incomplete cellular layer: Lines the edullary (marrow) cavity Covers trabeculae of spongy bone Lines entral canals Contains steoblasts, osteoprogenitor cells, and osteoclasts Is active in bone growth and repair Bone Formation and Growth Bone development o Human bones grow until about age 25 o Osteogenesis – bone formation o Ossificatio – the process of replacing other tissues with bone o Fibrodysplasia ossificans progressive (FOP) – rare genetic disease Bone forms in the wrong places eterotropic bones ) after minor injuries, replacing muscle tissue, etc. Treatment can be problematic because surgical removal can trigger more ossification Bone development o Calcification – the process of depositing calcium salts Occurs during bone ossification and in other tissues (rtilage) o Ossification Two main forms of ossification Endochondral ossification Intramembranous ossification 1. Endocondral ossification a. Ossifies bones that originate as hyaline cartilage 1) Most bones originate as hyaline cartilage b. There are seven main steps in endochondral ossification 1) Enlargemen t of artilage and chondrocytes . Calcification of cartilage begins and chondrocytes die. Chondrocytes are cells that produce cartilage. 1. Matrix is reduced to a series of small struts that soon begin to calcify. 2. Enlarged chondrocytes die and disintegrate, leaving cavities within the cartilage 2) Blood vessels grow into shaft. Cells in erichondrium differentiate into osteoblasts – forms bone around shaft (diaphysis) 1. The shaft of the cartilage becomes ensheathed in a superficial layer of bone. 3) Fibroblasts migrate to “ bone” cente r and differentiate into osteoblasts to create the rimary ossification center. Begins production of spongy bone 1. Blood vessels penetrate cartilage and invade central region 2. Fibroblasts migrate within blood vessels and begin producing spongy bone. 3. Bone formation spreads along the shaft towards the ends 4) Bone enlarges, osteoclasts appear and remove trabeculae in center of the diaphysis , creating medullary cavity (bone remodeling). Further growth increases length and diameter 1. Osseous tissue of the shaft become thicker and cartilage near each epiphysis is replaced by shafts. 5) Centers of epiphysis calcify , capillaries and osteoblasts enter area, forming secondary ossification centers 6) Epiphysis fills with spongy bone, leaving a thin cap of articular cartilage covering bone end. Epiphyseal cartilage (epiphyseal line in fully grown bones) at metaphysis separates diaphysis from epiphysis. On diaphysis side, osteoblasts replace cartilage with bone (occurs at same rate as new cartilage production on epiphyseal side) 7) At puberty, cartilage production slows while osteoblast activity increases. Causes epiphyseal cartilage to become narrower and narrower until it disappears and longitudinal growth of bone stops. (epiphyseal closure) Appositional growth o Compact bone thickens and strengthens long bone with layers of circumferential lamellae o As bone growth occurs to the outer surface, osteoclasts remove bone matrix located at the inner surface (usually at a slower rate) causes enlargement of medullary cavity as the bone gets larger in diameter Epiphyseal lines o When long bones stop growing, after puberty: Epiphyseal cartilage disappears Is visible on xrays as an epiphyseal line Mature bones o as long bone matures: osteoclasts enlarge medullary (marrow) cavity osteons form around blood vessels in compact bone 2. Intramembranous ossification a. Also called dermal ossification (because it occurs in the dermis) 1) Produces dermal bones such as mandible (lower jaw) and clavicle (collarbone) and flat bones of the skull b. There are five main steps in intramembranous ossification 1) Mesenchymal cells cluster and differentiate into osteoblasts. They secrete bone matrix components that crystallize with calcium salts 1. Starts about the eights week of embryonic development. 2. This type of ossification occurs in the deeper layer of the dermis, forming dermal bones 2) Some osteoblasts are trapped in the bone matrix and differentiate into osteocytes. Bone grows (spicules) outward from the ossification center 3) Blood vessels enter the area bringing nutrients – bone growth accelerates. picules interconnect and trap blood vessels within the bone. 4) Osteoblasts close to blood vessels continue to deposit bone matrix, creating pongy bone surrounding the vessels. 5) Remodeling around blood vessels produces osteons. Osteoblasts on bone surface (along with connective tissue there) become the periosteum. Blood supply of mature bones o Nutrient artery and vein a single pair of large blood vessels enter the diaphysis through the nutrient foramen femur has more than one pair o metaphyseal vessels supply the epiphyseal cartilage where bone growth occurs o periosteal vessels blood to superficial osteons secondary ossification centers Lymph and Nerves o The periosteum also contains: networks of ymphatic vessels sensory nerves Bone Remodeling Process of remodeling o The adult skeleton: Maintains itself Replaces mineral reserves Recycles and renews bone matrix Involves steocytes, osteoblasts and osteoclasts o Bone continually remodels, recycles and replaces o Turnover rate varies: If eposition is greater than removal, bones get stronger If emoval is faster than replacement, bones get weaker Exercise, Hormones and Nutrition Effects of exercise on bone o Mineral recycling allows bones to adapt to stress o Heavily stressed bones become thicker and stronger Bone degeneration o Bone degenerate quickly o Up to onethird of bone mass can be lost in a few weeks of inactivity produced by integumentary system Ex. Using a crutch for a few weeks will cause those leg bones to lose up to 1/3 of its mass. Normal Bone Growth and Maintenance Depend on Nutritional and Hormonal Factors o A dietary ource of calcium and phosphate salts plus small amounts of agnesium, fluoride, iron and manganese o The hormone calcitrol made in the kidneys, synthesis requires vmin D3 (cholecalciferol) helps absorb alcium (ca2+) and hosphorous (P) from digestive tract o Vitamin C is required for collagen synthesis and stimulation of osteoblast differentiation o Vitamin A stimulates osteoblast activity o Vitamin K and B12 help synthesize bone proteins o Growth hormone and thyroxine stimulate bone growth If GH increase occurs before puberty, antism can occur. If after, bones get thicker and not longer (megaly). Excessive artilage formation at epiphyseal cartilage. Caused by gene mutation affecting connective tissue throughout the body. Can cause life threatening cardiovascular problems Genetic mutation in collagen fibers o Estrogens and androgens stimulate teoblasts o Calcitonin (decrease blood calcium) and rathyroid hormone (increases blood calcium) regulate calcium and phosphate levels Calcium Homeostasis The skeleton as acalcium reserve o Bones store calcium and other minerals o Calcium is the most abundant mineral in the body Calcium ions are vital to: Membranes Neurons Muscle cells, especially heart cells Calcium regulation o Calcium ions in body fluids must be closely regulated o Homeostasis is maintained By calcitonin and parathyroid hormone (PTH) Which controls storage, absorption and excretion Calcitonin and Parathyroid Hormone Control Affect o Bones: where calcium is stored Digestive tract where calcium is absorbed Kidneys: where calcium is excreted Parathyroid hormone (PTH) pump up o Produced by parathyroid glands in neck o Increases calcium ion levels by: Stimulating steoclasts Increasing ntestinal absorption of calcium Decreasing calcium excretion at kidneys Calcitonin decreased calcium! o Secreted by cells (parafollicular cel in thyroid o Decreases calcium ion levels by: Inhibiting osteoclast activity Increasing calcium excretion at kidneys Fractures Fractures o Cracks or breaks in bones o Caused by physical stress Fractures are repaired in four steps o Bleeding Produces a clot (fracture hematoma) Establishes fibrous network Bone cells in the area die o Cells of the endosteum and periosteum Divide and migrate into fracture zone Calluses stabilize the break External callus of cartilage and bone surrounds break Internal callus develops in medullary cavity o Osteoblasts Replace central cartilage of external callus with spongy bone o Osteoblasts and osteocytes remodel the fracture for up to a year Initial swelling of fracture repair evident, however, remodeling reduces bone calluses Major types of fractures: o Transverse fractures – across the long axis o Displaced fracture – produce new/abnormal bone arrangements o Compression fractures – produced on vertebrae on hard falls to seat (often associated with osteoporosis) o Spiral fractures – twisting stress on length of bone o Compound fracture – bone fracture that breaks through the skin o Epiphyseal fractures – usually occurs where bone matrix is undergoing calcification, can permanently stop growth o Comminuted fractures – shatters bone into multiple fragments o Greenstick fractures – only one side of the bone is broken, other is bent generally occurs in children’s bones, not fully ossified o Colles fracture – break in distal portion of radius (usually caused by reaching out to cushion falls) o Pott’ fracture – occurs at ankle affecting tibia and fibula Effects of Aging on the Skeletal System AgeRelated Changes o Bones become thinner and weaker with age Osteopenia begins between ages 30 and 40 Women lose 8 percent of bone mass per decade; men lose 3 percent o The epiphyses, vertebrae, and jaw are most affected Resulting in fragile limbs Reduction in height Tooth loss Osteoporosis – severe bone loss o Affects normal function o Over age 45, occurs in 29 percent of women and 18 percent of men o Treatment: exercise (build up osteoblasts, slow own osteoclasts), sun exposure (vitamin D to absorb calcium) Hormones and Bone Loss o Estrogens and androgens help maintain bone mass o Bone loss in women accelerates after menopause Treatment: hormone replacement therapy (HRT) Cancer and Bone Loss o Cancerous tissues (bone, breast, and other tissue cancers) relase osteoclast activating factor That stimulates osteoclasts And produces severe osteoporosis Chapter 9 – Articulations An introduction to Joints • Articulations • Body movement occurs at joints (articulations) where two bones connect • Joint Structure • Determines direction and distance of movement (range of motion or ROM) • Joint strength decreases as mobility increases • The stronger the joint, then the joint = less mobile • The weaker the joint, then joint = more mobile Classification of joints: • Two Methods of Classification 1. Functional classification is based on range of motion of the joint 2. Structural classification relies on the anatomical organization of the joint Note: be careful distinguishing the difference between Functional and Structural classifications • Functional Classifications 1. Synarthrosis immovable joint ) most stable • E.g. sutures 2. Amphiarthrosis (slightly movable joint) moderately stable 3. Diarthrosis (freely movable joint) least stable • E.g. joint in the shoulder, elbow, knee, etc. • Structural Classifications 1. Bony – synotoses (synarthroses) 2. Fibrous – sutures and gomphoses (synarthroses); syndesmoses (amphiarthroses) 3. Cartilaginous – synchondroses (synarthroses) and symphyses [e.g. connects the two coccyx bones together] (amphiarthroses) 4. Synovial – only diarthroses Note: the functional classifications of these structural classifications are in the parentheses • Synarthroses (Immovable Joints ) • Are very strong • Edges of bones may touch or interlock • Four types of synarthrotic joints 1. Suture • Bones interlocked • Are bound by dense fibrous connective tissue • Are found only in skull 2. Gomphosis • Fibrous connection (periodontal ligament) • Binds teeth to sockets 3. Synchondrosis • Is a rigid cartilaginous bridge between two bones • Epiphyseal cartilage/plate of long bones • Between vertebrosternal ribs and sternum 4. Synostosis • Fused bones, immovable • Metopic suture of skull (fuses two sides of frontal bone) • Epiphyseal lines of long bones • Amphiarthroses • More movable than synarthrosis • Stronger than freely movable joint • Two types of amphiarthroses 1. Syndesmosis • Bones connected by ligaments (ex. Distal end of tibia and fibula) 2. Symphysis • Bones separated by fibrocartilage (ex. Pubic symphysis connects left and right coxal bones) • Synovial J ints Di (throses ) • Also called movable joints • At ends of long bones • Enveloped Within articular apsules • Lined with synovial membrane – not a true epithelial membrane; has cells called synoivalcytes that produce synoival fluid that lubricates the cavity, so the bones can articulate smoothly (provides protection against friction) Synovial Joints • Articular Ca tilages • Pad articulating surfaces within articular c psules • Prevent bones from touching • Smooth surfaces lubricated by synovial f uid • Has consistency of heavy molasses • Functions to reduce friction • Excessive exercise can damage bones if sufficient synovial fluid is not generated. • Synovial Fl id • Contains slippery proteoglycans secreted by fibroblasts • Resembles interstitial fluid, not much in joint (ex. Knee joint only has up to 3 mL of fluid) • Functions of synovial fluid • Lubrication – articular cartilage act as sponge filled with fluid. Compression of it pushes some fluid out. • Nutrient distribution – fluid circulates as joint moves, provides nutrients to chondrocytes in area • Shock absorption – viscocity of fluid increases with increased pressure • Accesory Structures • Cartilages • Cushion the joint • Fibrocartilage pad called a meniscus (or articular disc ; plural, menisci ), located between opposing bones in synovial joint • Fat ads • Adipose tissue superficial to the joint capsule • Protect articular cartilages • Outside the articular capsule (helps hold it in place) • Ligaments – continuous with periostea of articulating bones (no direct blood supply) • Support, strengthen joints • Sprain – ligaments with torn collagen fibers • Due to lack of blood supply, repair of ligaments can take time • Tendons • Attach to muscles around joint • Help support joint • Cover over the synoval joint to help stabilize the joint. • Bursae • Singular, bursa , a pouch • Pockets of synovial fluid, lined by synovial membrane • Cushion areas where tendons or ligaments rub • Bursitis – inflamed bursae causing pain, can result from repetitive motion, irritation, trauma, infection (ex. Bunion) • Factors That Stabilize Synovial Joints • Prevent injury by limiting range of motion • Collagen fibers (joint capsule, ligaments) • Shape of the articulating surfaces and menisci • Presence of other bones, muscles, or fat pads • Tension in the tendons of articulating bones • Note: pain receptors are not found on the inside of synovial joints. Pain felt due to joint damage results from nerves that monitor the capsule, ligaments, and tendons • Ever wonder why your knee does not bend forward? Its due to all these different structures that protect the knee! • Injuries • Dislocation l (ation ) – caused by extreme stress on joint • Articulating surfaces forced out of position • Damages articular cartilage, ligaments, joint capsule • Shoulder joint most prone to this injury • Subluxation • A partial dislocation • Note: “double jointed” people have weakly stabilized joints that are prone to dislocation or partial dislocation Movements • Three Types of Dynamic Motion Linear movement (gliding) 1. – movement within one plane 1. e.g. flexion and extension of the arm 2. Angular movement – one bone remains stationary while the other bone moves at an arc 1. e.g raising the arm in circumduction 3. Rotation – t he joint can move 1. E.g. moving the head side to side • Planes (Axes) of Dynamic Motion 1. Monaxial (1 axis) – ex. Forward/backwards 2. Biaxial (2 axes) – ex. Forward/backwards and side to side 3. Triaxial (3 axes) – ex. Forward/backwards, side to side, and angular • Types of Movement at Synovial Joints • Terms describe: 1. Plane or direction of motion 2. Relationship between structures 1. Gliding Movement 1. Two surfaces slide past eachother • Ex. Betwen carpal and tarsal bones, claviclce and sternum 2. Angular Movement Flexion • Angular motion in the anterior–posterior plane • Reduces angle between elements Extension • Angular motion in the anterior–posterior plane • Increases angle between elements Hyperextension • Angular motion • Extension past anatomical position • E.g. hyperextension of neck when you tilt your headback and look up at the ceiling Abduction • Angular motion in the frontal plane • Moves away from longitudinal axis Adduction • Angular motion in the frontal plane • Moves toward longitudinal axis Circumduction • Angular motion in a circular motion without rotation 3. Rotation Direction of rotation from anatomical position 1. Relative to longitudinal axis of body 2. Left or ight otation 3. Medial rotation ( inward rotation ) • Rotates toward axis • Ex. Bend arm at elbow, move hand at chest 4. Lateral otation (outward rotation) • Rotates away from axis • Ex. Bend arm at elbow, move had away from chest • Do not confuse this with pronation and supination! 5. Pronation • Rotates forearm, radius over ulna (Palm facing up) 6. Supination • Forearm in anatomical position (palm facing down) Note: pronation and supination are not the same as medial rotation and lateral rotation, respectively • Special Movements include specific articulations or unusual types of movements 1. Inversion • Twists sole of foot medially 2. Eversion • Twists sole of foot laterally 3. Dorsiflexion • Flexion at ankle (lifting toes) 4. Plantar f exion • Extension at ankle (pointing toes) 5. Opposition • Thumb movement toward fingers or palm (grasping) 6. Reposition • Opposite of opposition 7. Protraction • Moves anteriorly • In the horizontal plane (pushing forward) 8. Retraction • Opposite of protraction • Moving posteriorly (pulling back) 9. Elevation • Moves in superior direction (up) 10. Depression • Moves in inferior direction (down) 11. Lateral f exion • Bends vertebral column from side to side • Functional Classification of Synovial Joints 1. Gliding – flattened or slightly curved faces, limited motion (slight nonaxial/multiaxial) 2. Hinge – angular motion in a single plane (monaxial) 3. Pivot – rotation only (monaxial) 4. Condylar – oval articular face within a depression, motion in two planes (biaxial) 5. Saddle – two concave, straddled (biaxial) 6. Ballandsocket – round articular face in a depression (triaxial) • Joints A joint cannot be both mobile and strong The greater the mobility, the weaker the joint Mobile joints are supported by muscles and ligaments, not bonetobone connections Intervertebral Joints • Intervertebral Joints • C 2to L 5spinal vertebrae articulate: • At inferior and superior articular processes (gliding joints) • Between adjacent vertebral bodies (symphyseal joints) • Adjacent vertebral bodies separated by fibrocartilage intervertebral discs • Little gliding occurs here • Intervertebral D scs Pads of fibrocartilage • Separate vertebral bodies • Consists of: • Anulus fi rosus Tough outer layer • Attaches disc to vertebrae through collagen fibers • Nucleus p lposus Elastic, gelatinous core • Absorbs shocks • Gives disc resiliency • Note: discs account for almost ¼ length of vertebral column superior to sacrum. As we age, discs loses water content – less cushioning and also shortens our height • Vertebral Joints – also called symphyseal joints • As vertebral column moves: • Nucleus p lposus shifts • Disc shape conforms to motion • Intervertebral Ligaments • Bind vertebrae together • Stabilize the vertebral column • Damage to Intervertebral Discs • Slipped d sc • Bulge in anulus fibrosus • Invades vertebral canal • Caused by weakened posterior longitudinal ligaments of the vertebrae Herniated disc • • Nucleus pulposus breaks through anulus fibrosus • Presses on spinal cord or nerves The Shoulder Joint The Shoulder Jo nt • • Also called the glenohumeral joint • Ballandsocket diarthrosis • Between head of humerus and glenoid cavity of scapula • Allows more motion than any other joint • Is the least stable • Supported by skeletal muscles, tendons, ligaments • Most support provided by skeletal muscles of the rotator cuff • Shoulder Muscles ( Rotator Cu f) • Supraspinatus • Infraspinatus • Subscapularis • Teres minor • Processes of the Shoulder Joint • Acromion (clavicle) and coracoid process (scapula) • Project laterally, superior to the humerus • Help stabilize the joint • Shoulder separation –can result from hit to superior surface of shoulder (Forcing acromion downward) • Dislocation of the shoulder joint (at acromion of scapula and clavicle – at the acromioclavicular joint) • Relatively common The Elbow Joint • The Elbow Joint • A stable h inge joint (can cause flexion and extension) • With articulations involving humerus, radius, and ulna • Articulations of the elbow • Humeroulnar joint • Strongest and largest joint at elbow • Trochlea of humerus and trochlear notch of ulna • Limited movement • Humeroradial joint • Smaller joint • Capitulum of humerus and head of radius The Hip Joint • The Hip Joint • Also called coxal joint • Strong ballandsocket diarthrosis • Wide range of motion (not as high as shoulder) • Structures of the Hip Joint • Head of femur fits into socket of acetabulum of coxal bone • Which is extended by fibrocartilaginous acetabular labrum – increases joint cavity depth and helps seal in synovial fluid • Normally few dislocations here (it is a very strong joint). Hip fractures (of femoral neck or between trochanters) more common than dislocations. The Knee Joint A complicated hinge joint Transfers weight from femur to tibia Articulations of the knee joint o Two fe mur–tibia articulations At medial and lateral condyles o One between patella and patellar surface of femur The Articular Capsule and Joint Cavity o Has fibrocartilage pads (medial and lateral menisci) Located at femur–tibia articulations Cushion and stabilize joint Give lateral support o Most common knee injury – lateral surface of leg struck pushing it medially (tears medial meniscus) May lead to chronic problems, development of “trick knee” – feeling of knee being unstable Because it is soft tissue it does not repair as quickly as a tissue with good vascular supply. Even after this, there are receptors in the location that can become falsely stimulated. • Seven Major Supporting Ligaments 1. Patellar ligament (anterior) – [patella] attaches to tibia 2. & 3. Two popliteal ligaments (posterior) 4. & 5. Anterior and posterior cruciate ligaments (inside joint capsule) [ACL – ACL injuries tend to happen more in female athletes than in male athletes] “cruciate” – forms a cross. 1. Tibial collateral ligament (medial) 2. Fibular collateral ligament (lateral) Note: The ACL prevents hyperextension of knee (knee moves beyond 180 degrees) and anterior sliding of tibia from femur. 70% of all serious knee injuries involve the ACL. 36 times more likely to happen in female than in males. Effects of Aging on Joints • Degenerative Changes • Rheumatism • A pain and stiffness of skeletal and muscular systems • Arthritis – joint inflammation • All forms of rheumatism that damage articular cartilages of synovial joints • Can be caused by bacterial/viral infection, injury, physical stress, metabolic problems • Osteoarthritis – degenerative arthritis/degenerative joint disease (DJD) • Caused by wear and tear of joint surfaces, or genetic factors affecting collagen formation • Generally in people over age 60 – 25% women, 15% men • Rheumatoid Arthritis • An inflammatory condition • Involves the immune system – body attacks its own tissue (the joints) • Caused by infection, allergy, or autoimmune disease • Gouty Arthritis – crystal arthritis • Occurs when crystals (uric acid or calcium salts) form within synovial fluid • Due to metabolic disorders • Joint Immobilization • Reduces flow of synovial fluid • Can cause arthritis symptoms • Treated by continuous passive motion or CPM (therapy) • Bones and Aging • Bone mass decreases • Bones weaken • Increases risk of hip fracture, hip dislocation, or pelvic fracture Integration with Other Systems • Bone Recycling • Living bones maintain equilibrium between: • Bone building ( osteoblasts) osteoclasts) • And breakdown ( • Factors Affecting Bone Strength • Age • Physical stress for example, astronauts who do not experience stress, due to time spent in extended gravity, have reduced bone mass • Hormone levels – e.g. estrogen • Calcium and phosphorus uptake and excretion • Genetic and environmental factors • Bones Support Body Systems • Support and protect other systems • Store fat, calcium, and phosphorus • Manufacture cells for immune system • Make sure to know the diseases and disorders we talk about this semester! • Disorders in other body systems can cause: • Bone tumors – cancer cells cause a decrease in bone mass because they release a factor that causes osteoclasts to break down bone tissue • Osteoporosis – increased in females without estrogen (once menopause is reached) • Arthritis • Rickets (vitamin D deficiency)
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