Exam Two Notes Chapter Six Muscle System Function is to contract to produce movement or generate tension Principle functions o Produce movement or generate tension o Contraction shortens distance between bones o Skeletal muscle moves bone Muscle groups o Synergistic groups work together o Antagonistic groups oppose each other Three Types of Muscle Tissue Skeletal muscle o Moves body parts o Voluntary multinucleated Cardiac muscle o o Functions in the heart Involuntary single nucleus Smooth muscle o Surrounds hollow structures o Involuntary single nucleus Speed and Sustainability of Contraction Skeletal muscle fastest Cardiac muscle moderate Smooth muscle very slow o Partially contracted all of the time Muscle System Organization Skeletal Muscles o Attached to skeleton at two points Origin stationary bone Insertion moving bone Skeletal muscle moves bone Muscle contracts o o Insertion brought closer to origin Joint flexes Muscle Structure Composed of many muscle cells Muscle fibers muscle cells Long tube shaped o o Multinucleate o Packed with myofibrils o Myofibrils contain actin and myosin Skeletal Muscle Contractile Unit Sarcomere contractile unit o Myosin forms thick filaments o Actin forms thin filaments Z Lines attachment points for sarcomeres Fasicles are bundles of muscle fibers wrapped with connective tissue fascia o Arrangement of filaments gives rise to striated appearance of skeletal muscle Nerve Activation of Individual Muscle Cells Acetylcholine is released from motor neuron at neuromuscular junction Electrical impulse transmitted along T tubules Calcium released from sarcoplasmic reticulum Calcium Initiates the Sliding Filament Mechanism Thick filaments myosin Thin filaments strands of actin molecules Contraction formation of cross bridges between thin and thick filaments Mechanism of Muscle Contraction Troponin tropomyosin complex shifts position Calcium is released from sarcoplasmic reticulum Calcium binds to troponin Myosin binding site is then exposed Myosin heads form cross bridges with actin Actin filaments are pulled toward center of sarcomere Muscle Activity Two types of muscle fibers o Slow twitch endurance long duration contraction contain myoglobin Jogging swimming biking o Fast twitch strength white muscle short duration contraction Sprinting weight lifting tennis Exercise Training Strength training o Resistance training Short intense Builds more fast twitch myofibrils Aerobic training o Builds endurance o o Reach target heart rate for at least 20 minutes three times a week Increases blood supply to muscle cells February 7th 2014 Chapter Seven Blood The Circulatory System The circulatory system also referred to as the cardiovascular system ensures that blood flows throughout the body Functions of the Circulatory System Retrieves nutrients from the digestive system Exchanges gases with the respiratory system Carries wastes excess water and salts to the urinary system for disposal Carries some metabolic wastes to the liver Components of the Circulatory System Heart Blood vessels Blood o Arteries veins capillaries Blood A Key Component of Life Considered a specialized connective tissue that is instrumental in carrying out functions important for maintaining the body 1 Transportation o Blood is responsible for the transport of gases nutrients metabolic wastes excess salts and excess water 2 Regulation 3 Defense o Blood helps to regulate body temperature the volume of water in the body and the pH of body fluids o Blood contains cells that help protect the body against infections and illness Components of blood also help in prevention of excessive blood loss through the clotting mechanism Blood is Thicker Than Water Blood is thicker than water because its components are more dense than water In addition these components contribute to a viscosity that is five times higher than water Composition of Blood Contrary to its uniform appearance blood is composed of several components that fall into two major groups Liquid Components Plasma o Water o Electrolytes o Proteins o Hormones o Nutrients o Waste o Gases o Red blood cells o White blood cells o Platelets Formed elements which originate from stem cells in bone marrow There is whole blood and blood after being spun in centrifuge Whole blood has whole blood Blood after being spun in a centrifuge has 55 plasma Platelets and WBC 1 Red blood cells 44 Need to know for next test Stem Cells Found in the red marrow of certain bones and are the place of origin for all red blood cells and platelets Stem cells are non specialized when produced by bone marrow but have the capability as they multiply and become specialized in function Know Figure 7 5 for test Red Blood Cells RBCs Also called erythrocytes which literally means red cells in Greek Make up an abundance of the formed elements in blood Give blood its high viscosity and characteristic red coloring Most important cellular component in transport of oxygen to body tissues and the removal of carbon dioxide from the body Old and damaged RBCs are removed from circulating blood and destroyed in the liver and spleen Production of RBCs are regulated by secretion of a hormone when cells in the kidneys detect a decrease in the level of oxygen available for the body Secretion of erythropoietin from the kidneys stimulates stem cells to produce more red blood cells Structure of RBCs Mature RBCs are flattened doughnut shaped biconcave discs Shape allows flexibly and aids in gas exchange These cells do not contain a nucleus or any other cellular organelles and do not reproduce Lack of cellular organelles result in a life span of only approximately 120 days RBCs contain only the oxygen binding protein hemoglobin Hemoglobin Oxygen binding protein found in blood The protein is made of four polypeptide chains that each contain a heme group Heme groups are ring structures composed of nitrogen and carbon that each have one iron atom located at its center Each iron atom can bind one atom of oxygen therefore each hemoglobin protein can potentially bind up to four molecules of oxygen Hemoglobin that had four molecules attached oxyhemoglobin has a bright red color Hemoglobin with oxygen deoxyhemoglobin is typically dark purple color Hemoglobin is capable of binding carbon dioxide at sites from those used in oxygen binding and aiding in its removal from the body The percentage of blood that consists of red blood cells hematocrit is a relative measure of oxygen carrying capacity in the body