Chapter 36 The Integumentary, Skeletal, & Muscular System John Hizny Lexi Coolbaugh Sarah Schultz James Avery Adam Werner Section 36-1 Skin Largest organ in the body Part of integumentary system Integumentary includes skin, hair, nails, and number of important glands in skin. Skin has three layers 1. Outer layer - Epidermis 2. Inner Layer -Dermis 3. Lowest Layer - Hypodermis Supports the Epidermis Contains important cells for: Nerve endings Blood Vessels Smooth Muscle The body’s Sweat/Oil Glands are located here also Produces cells that are pushed toward the surface. Produces keratin as they move upward. Keratin – Tough, flexible protein ◦ Major protein found in fingernails ◦ Forms a tough waterproof layer on top of skin •Hair is produced from columns of cells that are filled with keratin and then…. DIE. •Clusters of cells make up Hair Follicles. •Toenails/fingernails are formed by keratin- forming cells for a flattened plate. Section 36-2 Bones All vertebrates have an internal skeletal system Bones store supplies of calcium and phosphorous Internal Skeletal System ◦ Provides support for the upper body ◦ Attachment sites for muscles ◦ Protects internal organs Bone Structure Periosteum- tough layer surrounding bones Inside the periosteum is a dense layer of compact bone. Spongy bone is found inside the compact bone. Osteocytes- Cells found in C & S bone. ◦ Help build and maintain bones Bone Growth Bones are produced by Cartilage. Cartilage is produced at growth plates & gradually is replaced by bone as the skeleton enlarges. Joints A place where two bones meet. 3 kinds of joints: ◦ Fixed Little or no movement between bones Mostly located in the skull ◦ Slightly Moveable Small amount of movement Mostly located in a Spinal Column or Ribs ◦ Freely Moveable Wide Range of movement Ex: Shoulders and hips Joints Continued Joints are enclosed by a Joint Capsule. Inside the capsule is Synovial Fluid ◦ Natural lubricant that reduces friction & allows the cartilage coated bones slip past each other easily Section 36-3 Muscle Tissue There are 3 types of muscle tissue: ◦ Skeletal ◦ Cardiac ◦ Smooth Each of these three types muscle, have a different cellular structure. Skeletal Muscle Tissue Generally attached to the bones of the skeleton and is usually under voluntary control. Skeletal muscle tissue is behind every conscious movement you make ◦ Ex: Lifting a weight This is because most skeletal muscle tissue is controlled directly by the nervous system. Cardiac Muscle Tissue Cardiac muscle tissue is found in just one place : The Heart Cardiac muscle tissue is striated, but the smaller Cardiac muscle cell have just one nucleus, and they are not under the direct control of the Central Nervous System Smooth Muscle Tissue Smooth muscle tissue is found in the walls of many internal organs, except the heart. The cells of the smooth muscle tissue are spindle shaped, have a single nucleus, and are not striated. Not always under the conscious control of the nervous system. Responsible for actions not under voluntary control. Muscle Structure Myosin- Thick filaments that are made of protein. Actin- Thin filaments that are made up of another protein. Sliding Filament Theory When hundreds of thousands of actin- myosin cross-bridges go through their cycle in a fraction of a second, the muscle cell contracts with siderable force. Muscle Contraction To make well-coordinated movement, muscle contractions must be carefully controlled. A single motor neuron may form synapse to one or several muscle cells. An impulse in the motor neuron causes the release of a neurotransmitter acetylcholine. ◦ This causes a new action potential. In turn causes the release of calcium ions into the cytoplasm of muscle cells. When calcium flows into the cytoplasm, cross-bridges form, and the muscle contracts. Muscles and Movements Muscles produce force by contracting. Attached to bones by tendons, a muscle can pull two bones together, using the joint between them as a lever. An individual muscle can pull by contracting, but cannot push. ◦ If that’s true, then how can you push a door open or do a pushup? The answer is that skeletal muscles are arranged in pairs. These pairs oppose each other and produce forceful movements in either direction. Section 36-4 Specialized Skeletal Muscle Fibers Skeletal muscles contain two main types of muscle fibers ◦ Red ◦ White Whose properties make them specialists at different kids of exercise. Red Muscle Fibers Contain large amounts of reddish oxygen- storing protein myoglobin. Red fibers have rich blood supplies and plenty of mitochondria to produce ATP. White Muscle Fibers Called fast- twitch muscle fibers and can generate powerful contractions. The contain few mitochondria , these fibers contain greater densities of contractile proteins than red fibers do. ◦ The powerful fibers fatigue easily, however, which means that they can produce maximum contractions for only a few seconds at a time. Exercise Muscle Cells Aerobic exercises, such as running, swimming, and bicycling cause your body system to become more efficient. ◦ Resistance exercise, such as weight lifting, increase muscle size.
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