Exam 3 Notes: Set Four
Exam 3 Notes: Set Four Bio 1144
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This 4 page Class Notes was uploaded by Murry on Saturday March 12, 2016. The Class Notes belongs to Bio 1144 at Mississippi State University taught by Thomas Holder in Spring 2015. Since its upload, it has received 19 views. For similar materials see Biology II in Biology at Mississippi State University.
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Date Created: 03/12/16
Exam 3 Notes: Set Four The Skeletal System • Skeletal System – endoskeleton in vertebrates; a constant, living structure • Functions of Skeletal System: o Movement o Support o Protection of soft body parts o Calcium and other mineral storage o Provide attachment sites for skeletal muscle o Production of blood cells • Bone tissue is strong yet lightweight because of air pockets/cavities (connective tissue) o Similar in strength of steel o 1 cubic inch of undamaged bone tissue can withstand a load of 19,000lbs • Flexible because of collagen fibers o 1mm across o Each fiber can hold 19lbs • Depository of Minerals o Calcium salts o Phosphorous salts o Provides for rigidity/hardness of bone o Loss of calcium softens bones (osteoporosis) • Bone Formation o Endochondral – bone replaces cartilage; majority of vertebrate’s bone formation o Intramembranous – bone forms within membranes of connective tissue; thin bone formation (Ex: plates of the skull) • Types of Bone Tissue o Compact – “ground bone; dense bone;” tightly packed together tissue and organized into structures called osteons § Osteons - structure unit of compact bone o Spongy – “bony spikes;” lightweight; loosely overlap each other; has no osteons; lots of air spaces • Long Bone Anatomy (ex: femur) o Epiphysis – section on the ends; contains spongy bone; where red bone marrow is produces à blood cells o Diaphysis – hollow in the middle (the shaft) o Medullary cavity – houses yellow bone marrow; adipose tissue and fat storage o Compact bone – layer all the way around the outside o Periosteum – entire outer covering of the bone, except ends of epiphyses o Articular cartilage – (hyaline cartilage); on ends of epiphyses; acts as a shock absorber and prevents bone from rubbing against bone • Bone Cells o Osteoprogenitor cells – the early developed bone cells; found in periosteum; differentiate into osteoblasts o Osteoblasts – bone forming cells; secrete bony matrix and collagen fibers o Osteocytes – mature osteoblasts fully surrounded by bone tissue they produced o Osteoclasts – bone resorbing cells; breakdown old or damaged bone tissue and remodels the bone • Microscopic Anatomy of Compact Bone o Osteon – structural/functional unit of compact bone; most oriented parallel to long axis of the bone o Osteon Canal – passageway for blood vessels, lymphatics, nerves o Lamellae – concentric rings of bone tissue o Lacuna – spaces between lamellae where osteocytes are located o Canaliculi – microscopic canals that connect lacunae to lacunae and lacunae to the osteon canal • Microfractures happen whenever you squeeze a pencil, hit your hand, clench your fingers, etc. A little fissure travels through the bone and hits osteon canal and stops whenever there is impact, but you can’t feel it because it’s so minor. A larger force is needed to cause a big fracture, which will travel straight through the osteon canal. • Skeleton (2 major parts) o Axial Skeleton – all bones associated with the central axis of the body; skull, ribs, sternum, vertebral column § 5 Types of Vertebrae: (number of each varies among vertebrates; i.e. a dog has more caudal bones than a human) • Cervical (neck) • Thoracic (upper back) • Lumbar (lower back) • Sacral (hip) • Caudal (tail/tailbone) § Vertebrae allow for flexibility and support and protection of spinal cord/nerve cord. o Appendicular Skeleton – all bones associated with the appendages; legs, arms, wings, fins, etc. § Appendage bones (limbs/fins/wings) • Forelimb bones (arms) o Humerous – the upper arm bone o Radius and Ulna – forearm bones o Carpals – wrist bones o Metacarpals – bones of hand o Phalanges – bones of fingers and toes (digits) • Hindlimbs (legs) o Femur – upper leg/thigh (largest bone in the body) o Patella – the knee cap o Tibia and Fibula – leg bones (tibia is larger than fibula) o Tarsals – ankle bones o Metatarsals – bones of feet o Phalanges – bones of toes and fingers (digits) • Jointed appendages makes movement easier. § Pectoral girdle (shoulders) • 2 scapula (shoulder bones) • 2 clavicles (collar bones) • Attaches front appendages to the axial skeleton § Pelvic girdle (hip) • Attaches hind appendages to axial skeleton • Pelvic bones fused to lower vertebral column § Joints – allow for enhanced movement on land and better contact with substrate (plus bones and skeletal muscle) The Muscular System • Tissue Types: o Cardiac Muscle – only associated with the heart, striated, involuntary, has 1-2 nuclei per cell, branching fiber cell type § Have intercalated disks – specialized junctions between cardiac muscles § Contractions pump blood o Smooth Muscle – not striated; more sheet-like, involuntary, 1 centralized nucleus, found in walls of internal organs and glands o Skeletal Muscle – striated, voluntary, multinucleated, mostly associated with skeleton, fiber cell type § Structure: • Muscle fascicles – a collection of skeletal muscle fibers bounded by connective tissue • Inside each fascicle are skeletal muscle cells called fibers • Each fiber is composed of myofibrils – a series of filaments • Myofilaments compose each filament; can be thin or thick o Contractile proteins are Actin (thin filaments) and Myosin (thick filaments)
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