Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Skeletal, Muscular & Integumentary Systems 1 Skeletal System FUNCTIONS: Supports the body Protects internal organs Provides for movement – levers act with muscles Stores mineral reserves Provides a site for blood formation 2 Skeletal System Divisions Axial – supports the central axis of the body (skull, vertebral column, rib cage Appendicular – bones of the arms, legs, pelvis & shoulder 3 Bone Structure Bones are living tissue – a solid network of cells & protein fibers that are surrounded by hardened deposits of calcium salts Outer layer = periosteum (tough connective tissue) Thick inner layer = compact bone with Haversian canals Second inner layer = spongy bone Innermost layer = bone marrow • Yellow marrow – mostly fat cells • Red marrow – produces rbc, some wbc, platelets, contains stem cells 4 Bone Development An embryo skeleton is almost entirely cartilage Strong, flexible connective tissue No blood vessels Cartilage is replaced by bone during the process of ossification Ossification begins 6-7 months before birth Bone growth occurs at the ends of long bones 5 Bone Connections Joint – place where one bone connects to another bone Bones connect to bones through ligaments Joint Types: Immovable joint (fixed joints) – allow no movement between bones that touch each other (skull) Slightly movable joint – small amount of restricted movement (slight separation from each other) (vertebrae) Freely movable joint – permit movement - ball-and-socket - hinge - saddle - pivot 6 7 Muscular System Muscles are specialized tissue that can contract and relax. Muscles work with the skeletal system to allow movement. Three types of muscles: Skeletal – attached to bones to allow voluntary movement Smooth – usually not under voluntary control Cardiac – heart muscle 8 Skeletal Muscle Alternating light & dark bands (striation) Usually voluntary control Large cells that can have many nuclei Found all over the body – usually attached to bones 9 Smooth Muscle Spindle –shaped cells One nucleus Found in walls of hollow structures (blood vessels, stomach, intestines) Involuntary control 10 Cardiac Muscle Striated Has one or two nuclei per cell Usually involuntary control Found ONLY in the heart 11 Skeletal Muscle Anatomy Skeletal muscle consists of bundles of muscle fibers Bundles of muscle fibers are composed of individual muscle fiber cells Each muscle fiber consists of myofibrils that have light & dark bands (striations) Each myofibril is made up of thick filaments (myosin protein) & thin filaments (actin protein) A unit of alternating actin & myosin = sarcomere, separated by a dense “Z band” matter 12 (Click) 13 Muscle Contraction Control The axon terminal contains vesicles with the neurotransmitter Acetylcholine (Ach). An action potential causes the vesicles to release the Ach across the neuromuscular synapse. This causes the release of Ca+ in the muscle fiber causing actin & myosin to interact. As long as Ach is released, the muscle will contract. As soon as the Ach is stopped, the muscle relaxes. 14 Muscles and bones Skeletal muscles connect to bones through tendons. There are usually several tendons connecting many muscles around a joint. Muscles usually act in opposing pairs. 15 Integumentary System Integument = “covering” Skin Hair Nails Some glands (found in skin) Skin primary functions: Barrier against infection & injury Helps regulate body temperature Removes waste products Protection against UV radiation 16 Skin Anatomy Epidermis - Two layers: dead outermost layer & inner living layer - Keratin - Melanin - No blood vessels Dermis - Next inner layer - Collagen - Many blood vessels - Nerve endings - Sensory receptors - Glands: sweat & sebaceous - Smooth muscles - Hair follicles Hypodermis - Mainly fat storage Contains larger blood vessels & larger nerve fibers 17 Hair & Nails Formed from keratin (fibrous protein) Forms horns, reptile scales, bird feathers, porcupine quills Hair is produced at the base by hair follicles Sebaceous (oil) glands help maintain hair health 18 Nails grow from an area of rapidly dividing cells = nail root. 19