Reading Essentials for Biology Glencoe (794133), страница 95
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In bones that endin cartilage, bone growth occurs at both ends of the bones. Duringthe teen years, increased production of sex hormones causes theosteoblasts, the cells that form bone, to divide more rapidly. Thisresults in a growth spurt. These hormones also cause the growthcenters at the ends of the bones to slow production. As these cellsbegin to die, growth slows. After growth stops, bone-formingcells repair and maintain the bones.Copyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Skeletal System FunctionsThe primary function of the skeleton is to provide a frameworkfor the body tissues.
The skeleton also protects internal organs,such as the heart, the lungs, and the brain.The human skeleton allows for efficient movement. Musclesthat move body parts need to be firmly attached to a strong structure that the muscles can pull against. The skeleton providesthese attachment points.Bones also produce blood cells. Red blood cells, white bloodcells, and cell fragments that are needed for blood clotting areproduced in the red marrow of a bone. Red marrow is found inthe humerus, the femur, the sternum, the ribs, the vertebrae, andthe pelvis.
Yellow marrow is found in many other bones. Yellowmarrow consists of stored fat. The stored fat can be used in timesof need.5. Why is calcium importantin the human diet?________________________What other functions do bones have?Your bones store minerals. Minerals stored in bones includecalcium and phosphate. Calcium is needed to form strong, healthybones.
It is important to eat foods that are rich in calcium. Thesefoods include milk, yogurt, cheese, lettuce, spinach, and otherleafy vegetables.READING ESSENTIALS________________________________________________Chapter 34417NameDateClassSection34.2Bones: The Body’s Support, continuedWhat are some common bone injuriesand diseases?As people get older, their bones age and change.
A diseasecalled osteoporosis (ahs tee oh puh ROH sus) involves a loss ofbone volume and minerals. These losses cause the bones tobecome more porous and brittle. Osteoporosis is most commonin older women because they produce less estrogen, a hormonethat helps bones form.When bones break, a doctor can move them back into position.The doctor will put a cast or a splint over the bone to hold it inplace until the bone tissue regrows.◗ After You ReadMini Glossaryaxial skeleton: a part of the skeleton thatincludes the skull and the bones that support it, such as the vertebral column, ribs,and sternumbursa: fluid-filled sac located on the outside ofsome joints; sacs decrease friction, and helpbones and tendons move smoothly togethercompact bone: hard bone composed of repeating units of osteon systems; this type ofbone tissue covers or surrounds every bonejoint: found where two or more bones meet;most joints help bones move in relation toeach otherligament: a tough band of connective tissue thatattaches one bone to anotherosteoblast (AHS tee oh blast): potential bone cellosteocyte (AHS tee oh sit): living bone cellthat receives oxygen and nutrients fromsmall blood vessels running within theosteon systemsred marrow: the production site for red bloodcells, white blood cells, and cell fragmentsthat are needed for blood clottingspongy bone: has many holes and spaces and issurrounded by compact bonetendon: thick band of connective tissue that connects muscles to bonesyellow marrow: consists of stored fat; found inmany bones1.
Read the terms and their definitions in the Mini Glossary above. Use the space below towrite a brief paragraph describing bones and bone structure. Use at least six of the termsfrom the glossary in your paragraph.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________418Chapter 34READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.appendicular (a pen DI kyuh lur) skeleton: includesthe bones of the arms and legs, the shoulder and hip bones, wrists, ankles, fingers,and toesNameDateClassSection34.2Bones: The Body’s Support, continuedCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.2.
Place the sentences below in the correct sequence to show the development of bone cells ina human.1. Embryo2. Ninth week3.4.5. Osteoblasts6.a. Bone begins to replace cartilage.b. Osteoblasts secrete collagen.c. Embryonic cartilaginous skeleton forms.d. Blood vessels in the embryo penetrate the membrane covering the cartilage.e. Minerals in the bloodstream are deposited in living bone cells.f.
This stimulates embryonic cells to become osteoblasts.3. What is the difference between yellow and red marrow?________________________________________________________________________________________________________________________________________________________________________Visit the Glencoe Science Web site at science.glencoe.com to findyour biology book and learn more about bones, the body’s support.READING ESSENTIALSChapter 34419NameDateClassSection34.3 Muscles for LocomotionSC.F.1.4.6 The student knows that separate parts of the body communicate with each other using electrical and/orchemical signals.
Also covers SC.F.1.4.1, SC.F.1.4.7, SC.F.1.4.8◗ Before You ReadMost humans can control how they run, walk, jump, wave their arms, and touch their toes. Duringall these activities, the human heart keeps beating without any prompting. On the lines below,explain the ways in which you keep your heart and other muscles strong.______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________◗ Read to LearnIdentify MainIdeas As you read this section, highlight where eachtype of muscle tissue is found.In another color, highlightwhat each muscle tissue does.SmoothmusclefiberNucleusCardiacmusclefiberStriationAlmost half of your body mass is muscle.
A muscle is groups offibers, or cells, that are bound together. Almost all the musclefibers you will ever have were present at birth. There are threemain types of muscle tissue in your body.Smooth muscle is found in the walls of your internal organsand in blood vessels. Smooth muscle is made of sheets of cellsthat line organs, such as the digestive tract and the reproductivetract. The most common job of smooth muscle is to squeeze. Asmooth muscle applies pressure on the space inside the tube ororgan it surrounds. This pressure moves material through theorgan.
For example, food moves through the digestive tract becausesmooth muscles squeeze the material as it moves through the tract.Gametes move through the reproductive system because they aresqueezed by smooth muscle. You do not consciously control asmooth muscle and its contractions. Therefore, smooth muscle isconsidered an involuntary muscle.
It contracts by itself.Cardiac muscle is also an involuntary muscle. Cardiac musclemakes up your heart muscle. Cardiac muscle fibers are connected,forming a network that helps the heart muscle contract efficiently.Cardiac muscle can generate and conduct electrical impulses.These impulses are necessary for the regular, rhythmic contractions of the heart—your heartbeat. Cardiac muscle is found onlyin the heart.Nucleus420Chapter 34READING ESSENTIALSCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Three Types of MusclesNameDateClassSection34.3Muscles for Locomotion, continuedSkeletal muscle is the third type of muscle tissue.
Skeletalmuscle is attached to and moves your bones. Most of the musclesin your body are skeletal muscles. You can control their contractions. When you want to move your arm or your leg, the musclesare under your control. A muscle that contracts under consciouscontrol is called a voluntary muscle. Skeletal muscles are voluntary muscles.SkeletalmusclefiberNucleusStriationCopyright © by Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.Skeletal Muscle ContractionMovement occurs because muscles can contract and relax.Most of your skeletal muscles work in opposing pairs. When onemuscle contracts, another relaxes.
When you bend your arm,the biceps muscle, which is located onthe front of your arm, contracts. TheContractingmuscle on the back of your arm, thebicepstriceps, relaxes. When you straightenyour arm, the biceps relaxes, and thetriceps contracts.Muscle tissue is made up of muscleRelaxedfibers. Muscle fibers are long muscle cellstricepsthat are connected. Each fiber is madeup of smaller units called myofibrilsRelaxed(mi oh FI brulz). Myofibrils consist of evenbicepssmaller protein filaments that can be eitherthick or thin. The thicker filaments areContractingmade of the protein myosin. The thinnertricepsfilaments are made of the protein actin.Each myofibril can be divided into sections called sarcomeres (SAR kuh meerz).Sarcomeres are the functional unitsof muscles.One of the best explanations for how muscle contraction occursis called the sliding filament theory.
The sliding filament theory1. What is the sliding filastates that when a muscle receives a signal from a nerve, the actinment theory?filaments in each sarcomere slide toward each other. This shortens the sarcomeres in a fiber. This shortening causes the muscle________________________to contract. The myosin filaments do not move.________________________Muscle Strength and Exercise________________________Muscle strength does not depend upon the number of fibers ina muscle. The number of fibers in each muscle was fixed beforeREADING ESSENTIALSChapter 34421NameDateClassSectionMuscles for Locomotion, continued2. Does muscle strengthdepend upon the numberof fibers in a muscle or thethickness of the fibers?________________________________________________________________________3.
Is lactic fermentation anaerobic or anaerobicprocess?________________________birth. Muscle strength depends on the thickness of the fibers. Italso depends upon how many of the fibers contract at one time.Regular exercise stresses the muscle fibers. This stress increasesthe size of the fibers. When you exercise regularly, your musclefibers increase in diameter by adding myofibrils.Remember that ATP is the energy-storing molecule in cells.ATP is produced during cellular respiration. Muscle cells are continually supplied with ATP from both aerobic and anaerobicprocesses.
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