Biology Chapter 49

Biology Chapter 49 - Chapter 49: Sensory and Motor...

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Chapter 49: Sensory and Motor Mechanisms Animal Skeletons Functions in Support, Protection and Movement - Animal behavior flows in a seamless cycle involving continuous brain operations that generate actions Types of Skeletons - Three main functions of skeleton are support, protection, and movement - Hard skeleton provides protection for soft tissues - Skeletons aid in movement by giving muscles something to work from against - Three main types of skeletons o Hydrostatic Skeleton Consists of fluid held under pressure in a closed compartment Peristalsis: A type of movement on land produced by rhythmic waves of muscle contractions passing from front to back Well suited for life in aquatic environments Cushion internal organs from shocks and provide support for crawling and burrowing in terrestrial animals o Exoskeleton Hard encasement deposited on the surface of an animal Animals grow, enlarges its shell by adding to its outer shell Jointed exoskeleton is a cuticle Cuticle consists of chitin, as polysaccharide similar to cellulose, embedded in a protein matrix, combined strength and flexibility o Endoskeletons Consists of hard supporting elements, buried within soft tissue Mammalian skeleton built from more than 200 bones, some fuse together, others connected by joints by ligaments that allow freedom of movement Vertebrate divided into two main parts Axial Skeleton: Consisting of the skull, backbone, and rib cage Appendicular Skeleton: Made up of limb bones and the pectoral and pelvic girdles that anchor the appendages to the axial skeleton Physical Support on Land - Body posture, the position of legs relative to the main body, is a more important structural feature in supporting body weight - Muscles and tendons hold the legs straight and positioned under the body, bear most of the load Muscles Move Skeletal Parts by Contraction - Two systems of cell motility o Microtubules, beating of cilia and the undulations of the flagella o Microfilaments, contractile elements of muscle cells Vertebrate Skeletal Muscle - Skeletal Muscle: Attached to the bones and is responsible for their movement o Consists of a bundle of long fibers running parallel to the length of the muscle o Muscle fiber is a bundle of smaller myofibrils, arranged longitudinally Myofibrils composed of two kinds of myofilaments Thin Filaments: Two strands of actin and one strand of regulatory protein coiled around one
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Biology Chapter 49 - Chapter 49: Sensory and Motor...

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