Bio 254 Exam Questions with Answers 2025 version.

Bio 254 Exam Questions with Answers 2025 version. bone functions Protect soft tissues, point of attachment, blood producing, stores inorganic salts Skull bones protect brain, ears, eyes Rib cage protects the heart and lungs Bones provide Shape for head, face, thorax, limbs Long bones long and narrow, have expanded ends short bones Cube like, sesamoid (round) bones, they are embedded in tendons flat bones platelike with broad surfaces irregular bones variety of shapes, most are connected to other bones Epiphysis the end part of a long bone, articular cartilage covers, spongy bone make up Diaphysis shaft of long bone, composed of compact bone, medullary cavity ( hollow chamber contains marrow), marrow (red/yellow) Periosteum Encloses bone, dense connective tissue Endosteum lines the medullary cavity Osteocytes are _____________ in lacunae connected by canaliculi Mature bone cells extracellular matrix a collection of extracellular molecules secreted by cells that provides structural and biochemical support to the surrounding cells. collagen fibers provides flexibility and strength inorganic salts make bone hard Canaliculi Hairlike canals that connect lacunae to each other and the central canal Lacunae small cavities in bone that contain osteocytes compact bone Hard, dense bone tissue that is beneath the outer membrane of a bone. Weight bearing, resists compression, blood vessels provide nutrients spongy bone Layer of bone tissue having many small spaces and found just inside the layer of compact bone. Trabeculae (support), flexible, reduce bone weight trabeculae supporting bundles of bony fibers in cancellous (spongy) bone Bones form by replacing connective tissue intramembranous bones broad/ flat bones (connective tissue), skull, clavicles, sternum, facial bones, mandible, maxilla, zygomatic intramembranous ossification Replacing embryonic connective tissue endochondral bones most bones of the skeleton, hyaline cartilage, femur, humerus, radius, tibia, phalanges, vertebrae endochondral ossification process in which bone forms by replacing hyaline cartilage Diaphysis separated from epiphysis by Epiphyseal plate Layer 1- zone of resting cartilage Closest to end of epiphysis, resting cells, anchor epiphyseal plate Layer 2- zone of proliferating cartilage Rows of young cells, undergoing mitosis Layer 3- zone of hypertrophic cartilage Older cells left behind, matrix calcified, chondrocytes die Layer 4- zone calcified cartilage Thin layer of dead cartilage cells and calcified matrix growth at epiphyseal plate -osteoclasts break down calcified matrix -osteoblasts then invade, replacing cartilage with bone tissue -bone can continue to grow in length, as long as cartilage cells of epiphyseal plate remain active -when ossification centers meet, and epiphyseal plate ossifies, bone can no longer grow in length -bone can thicken by depositing compact bone on outside, under periosteum bone resorption the removal of minerals and collagen fibers from bone by osteoclasts bone deposition the addition of minerals and collagen fibers to bone by osteoblasts Vitamin D calcium absorption; deficiency causes rickets, osteomalacia Vitamin A osteoblast & osteoclast activity; deficiency retards bone development Vitamin C collagen synthesis; deficiency results in slender, fragile bones growth hormone stimulates cartilage cell division Insufficiency-child can lead to pituitary dwarfism Excess-gigantism in child, acromegaly in adult thyroid hormone Replacement of cartilage with bone in epiphyseal plate, osteoblast activity parathyroid hormone A hormone of the parathyroid gland that regulates the metabolism of calcium and phosphorus in the body. Bone breakdown, stimulates osteoclasts sex hormones promote bone formation; stimulate ossification of epiphyseal plates physical stress stimulates bone growth Hematoma a solid swelling of clotted blood within the tissues. cartilaginous callus phagocytes remove debris, fibrocartilage invades bony callus osteoblasts invade, hard callus fills space Remodeling Bone restore close to original shape Hematopoiesis blood cell formation; occurs in red bone marrow yellow marrow stores fat but does not produce blood cells Inorganic salts 70% of bone marrow, most abundant salt is crystals of hydroxyapatite (calcium phosphate) Magnesium ions Component of bone tissue and required for certain metabolic processes Carbonate ions component of bone tissue along with calcium Osteoporosis loss of bone density and mineralization Calcium nerve impulse, blood clotting, muscle contraction, B12 absorption, blood calcium regulated by PTH and CT number of bones in adult skeleton 206 bones Axial bones 80 bones in skull, middle ear bones, hyoid bone, vertebral column, and rib cage appendicular skeleton (126 bones) pectoral girdle, upper limbs, pelvic girdle, lower limbs Joints (articulations) connections between bones, bone growth, enable body to move, skeletal muscle contraction structural joints fibrous, cartilaginous, synovial Functional joints synarthroses, amphiarthroses, diarthrotic Synarthrotic immovable joint Amphiarthrotic slightly movable Diarthrotic freely movable fibrous joints (3types) consists of inflexible layers of dense connective tissue, holds the bones tightly together. Syndesmosis, sutures, gomphosis Syndesmosis bones united by fibrous connective tissue, forming an interosseous membrane or ligament sutures joint Between flat bones of skull, sutures like ligament connects bone gomphosis joint Cone shaped in jaw bone, synarthrotic, periodontal ligament cartilaginous joints (2types) allow only slight movement and consist of bones connected entirely by cartilage, hyaline and fibro Synchondrosis -bones are bound by hyaline cartialge -Ex. rib attachment to sternum by costal cartilage Temporary symphysis A type of joint that has grown together forming a very stable connection. Fibrocartilage between bones, articular surfaces (hyaline), pubic symphysis, intervertebral discs Synovial (6 types) Most, all diarthrotic, outer layer( ligaments), inner layer(sunovial membrane secreates synovial fluid) ball and socket joint hip and shoulder joints, widest range of motion, multiracial, cup shaped cavity condylar joint -between metacarpals and phalanges -between radius and carpals Biaxial, horotation, ellipsoidal joint, back and forth, side-side movement Plane joint wrist and ankle Nonaxial movement, back and forth and twisting, gliding joint, slightly curved, and almost flat Hinge joint Joint between bones (as at the elbow or knee) that permits motion in only one plane Uniaxial, convex fits into concave pivot joint Atlas (c1), and dens (c2) Uniaxial (rotation only) Trochoid joint saddle joint carpal and metacarpal of the thumb Biaxial Concave and convex surfaces Seller joint Structure of synovial joint Articular cartilage covers articular ends of bones Joint capsule, consists of 2 layers: - Outer fibrous layer, composed of ligaments - Inner layer, synovial membrane, which secretes synovial fluid Fixed end origin Movable end insertion movement of muscles Contracts and twitches Fibers pull Insertion towards origin Synthetic Replace joints (arthritis/injury) steel and titanium replace larger joints Silicon Smaller joints Abduction Movement away from the midline of the body Adduction Movement toward the midline of the body Flexion Decreases the angle of a joint Extension increases the angle of a joint Dorsiflexion Decreasing the angle of the ankle joint Platarflexion moving the foot downward Rotation Moves on axis Circumduction the circular movement at the far end of a limb Supination Palm upward Pronation palm downward Eversion Away from midline (foot) Inversion Towards midline (foot) Protraction Forward motion Retraction backward movement Elevation upward movement of a body part Depression downward movement of a body part Sprain Tearing of connective tissue, without bone dislocation Bursitis inflammation of a bursa usually caused by a blow or friction. Overuse or stress Arthritis Inflammation, swelling, pain in a joint rheumatoid arthritis autoimmune disease Osteoarthritis degenerative joint disease, most common, aging Lyme arthritis Lyme disease - caused by spirochete bacterium carried by deer ticks/black leg ticks. May be treated with anibiotics if caught early on skeletal muscle composed of skeletal muscle tissue, nervous tissue, blood, connective tissue Muscle functions producing movement, maintaining posture, stabilizing joints, generating heat, pumping blood, peristalsis Peristalsis Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system. Connective tissue covering epimysium, perimysium, endomysium Epimysium surrounds entire muscle Perimysium surrounds fascicles Endomysium surrounds each muscle fiber within a fascicle Skeletal muscle fibers= muscle cells Multinucleated, sarcolemma, sarcoplasma Myofibrils protein structures that make up muscle fibers thin filaments actin, troponin, tropomyosin thick filaments myosin Triad 1 T-tubule and 2 terminal cisternae (sarcoplasmic reticulum) Sarcomeres a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band. I band of sarcomere contains only thin actin filaments A band of sarcomere contains all of the thick myosin filaments plus any overlapping think actin filaments, and some thin filaments H zone of sarcomere contains thick filaments of myosin only z-line of sarcomere defines boundaries of sarcomere and anchors thin, actin filaments, z disc M line of sarcomere middle of sarcomere thick skeletal muscle filaments Myosin heads form cross bridges Thin skeletal muscle filaments Actin protein, myosin binding site Troponin and tropomyosin proteins prevent cross bridge formation when muscle is not contracting neuromuscular junction the junction between a nerve fiber and the muscle it supplies, synapse, myoneural junction parts of neuromuscular junction Motor neuron, motor end plate, synaptic cleft, synaptic vesicles, neurotransmitters Acetylcholine (ACh) A neurotransmitter that enables learning and memory and also triggers muscle contraction. Release from synaptic vesicles by nerve impulses motor end plate ACh binds to ACh receptors action potential a neural impulse; a brief electrical charge that travels down an axon AcH causes changed in membrane permeability to Na and K, generates muscle impulse Impulse causes release of Ca from SR which leads to muscle contraction myasthenia gravis autoimmune neuromuscular disorder characterized by weakness of voluntary muscles 1/3 normal number of Ach receptors Treatment: inhibit Ach, immunosuppressant, plasma exchange anaerobic respiration Glycolysis, In the cytoplasm, produces little ATP aerobic respiration Citric acid cycle and electron transport, in the mitochondria, most ATP, myoglobin stores extra oxygen in muscles, fibers increase capillaries Oxygen debt During rest and moderate exercise Respiratory/ cardiovascular supply enough O2 to support aerobic respiration Anaerobic (Lactic Acid) Threshold Shift in metabolism from aerobic to anaerobic, during strenuous muscle activity, when the above systems cannot supply the necessary O2. Lactic acid is produced. heat production muscles contract and cause blood to flow to the area heat Heat is a by product of cellular respiration in ACTIVE cells Blood transports heat throughout body core latent period time between application of a stimulus and the beginning of a response in a muscle fiber period of contraction cross bridge formation; tension increases period of relaxation of muscle twitch cross bridge detaches, Ca2+ reenters terminal cisternae, Tension declines to zero Length of muscle fiber Amount of force it can develop optimum length of muscle Resting length of muscle fibers, greatest force to develope Stretched Less force, myosin headed can't reach binding site Shortened Less force, compressed sarcomeres can't shorten excitation-contraction coupling connection between muscle fiber stimulation and muscle contraction muscle relaxation Ca2+ moves back into sarcoplasmic reticulum by active transport. Requires energy Ca2+ moves away from troponin-tropomyosin complex Complex re-establishes its position and blocks binding sites. muscle stimulation Muscle impulses cause SR to release Ca+2 ions into cytosol Ca+2 ion binds to troponin to change its shape The position of tropomyosin is altered Binding sites on actin are now exposed Myosin heads bind to actin, forming cross-bridges Sliding filament model of muscle contraction sarcomeres shorten, actin (thin) and myosin (thick) slide past one another H zone/ I bands narrow Z lines move closer together Thin/thick filaments do not change length Overlap between filaments increase cross bridge cycle repeated sequential interactions between myosin and actin filaments at cross-bridges that cause a muscle fiber to contract ATP splits Relaxation When neural stimulation of muscle fibers stop troponin-tropomyosin complex covers binding sites on actin ATP reserves -first source of energy for muscle contraction -muscle cells store only a small amount Creative phosphate Initial sources of energy to regenerate ATP from ADP and P Cellular respiration Motor units a motor neuron and all the muscle fibers it controls coarse movements large numbers of fibers in a motor unit Precise movement Fewer muscle fibers in motor unit Receuitment Increase motor units to complete a task isotonic contraction Equal force, changes length concentric contraction shortening of muscle eccentric contraction lengthening of muscle isometric contraction Muscle contracts but there is no movement, muscle stays the same length, change in force hypertrophy the enlargement of an organ or tissue from the increase in size of its cells. Skeletal muscle atrophy Decrease in size and length of skeletal muscle (unused) Agonist Muscle that causes an action (prime mover) Prime movement Agonist primarily responsible for movement Synergist Muscle that assists a prime mover Antagonist Contraction cause movement in the opposite direction of the prime mover smooth muscle 30-200um, 3-6um, walls of hollow organ, vasoconstriction, peristalsis, movement of walls, involuntary, contraction/relaxation slowly, self exciting, rhythmic, single Nucleus, striation absent, no transverse T. Shorter, single (central), elongated, tapering ends, myofilaments randomly organized, lack striamtions, lack transverse tubules, sr not well developed cardiac muscle Involuntary muscle tissue found only in the heart. Pumping action, contraction as a unit, self exciting, rhythmic, remains refractory until contraction ends, single nucleus, striation present, transverse tubules developed, intercalated discs connect cells skeletal muscle 30 cm, 10-100 um, movement of bones at joint, maintenance of posture, voluntary, contracts/relaxes rapidly, multi-nuclei, striatum present, transverse tubule developed