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ASA Chapter 4 The Human Body ALABAMA 7TH GRADE SCIENCE STANDARDS COVERED IN THIS CHAPTER INCLUDE: Relate major tissues and organs of the skeletal, circulatory, reproductive, muscular, respiratory, nervous and digestive systems to their functions. 3 : • Sc . •• you think of the human body as a team, then the organ systems within it would be the players This team must work together in order for the body to maintain homeostasis • :. INKS .l.LJI4M;_44cIwI F ACO65 Let’s review the definition of homeostasis It is the process of maintaining a constant internal environment, despite changing environmental conditions. It is how we “regulate ourselves.” Here are a few examples: . . . Sweating cools us and helps us maintain a constant internal temperature. We drink water to remain hydrated and maintain our body’s water balance. We excrete waste products to maintain a clean bloodstream. To accomplish homeostasis, the combined efforts of cells, organs and organ systems are required. We won’t look at every part of our “human body team,” but we will examine several “star players.” . Co In Co CO Co C? ui C) 0 D 0 I- 0 z 0 0 (U E 0 C) 0 0 C (U I.) 0 E © 0) >‘ 0. 0 C) Figure 4.1 The Human Body Team 37 The Human Body Table 4.1 Overview ofHuman Body Systems System Major Parts and Organs Respiratory nose, trachea, bronchial tubes, lungs, alveolus and diaphragm Circulatory heart, veins, arteries and capillaries Digestive tongue, teeth, salivary glands, esophagus, stomach, pancreas, liver, gall bladder, small intestine, appendix and large intestine Skeletal skull, vertebral column, sternum, ribs, humerus, radius, ulna, carpals, metacarpals, phalanges, pelvic girdle, femur, patella, tibia, fibula, tarsals and metatarsals Immune lymphatic system, spleen, tonsils, thymus, leukocytes and bone marrow Lymphatic lymph nodes, tonsils, thymus and spleen Muscular involuntary (smooth muscles), heart (cardiac muscle) and voluntary (striated muscles) Nervous brain (cerebrum, medulla, cerebellum), spinal cord and nerve cells Excretory kidney, blood vessels, bladder, ureter, urethra, skin and sweat glands Reproductive male: testes, vas deferens, seminal vesicle and penis female: ovary, oviduct, uterus, cervix and vagina REsPIRAToRY SYSTEM p. C? w The respiratory system allows our bodies to obtain oxygen from the air. Respiration refers to the movement of air in and out of the lungs. Respiration happens when we breathe in (inspiration). To take a breath, a special muscle called the diaphragm must contract. The diaphragm is a flat muscle that runs across the body cavity below the lungs. When the diaphragm contracts, it increases 0 -J 0.- 0 z 0 0 E 0 0 0 0 ro 0 E © Figure 4.2 Respiratory System 0. 0 0 38 Chapter 4 the total overall volume of the lungs, causing air to rush into the body. When the diaphragm relaxes, it decreases the volume of the lung cavity, causing air to leave the body. During inspiration, air enters the nose or mouth, where it passes through the trachea (a hollow tube made of cartilage), bronchial tubes and into the alveoli. are air sacs rich in blood vessels, where gases exchange between lungs and blood. Oxygen then diffuses into the cells, and carbon dioxide diffuses out of the cells. Alveoli When we breathe out, we rid our bodies of carbon dioxide. Breathing out is called leave the body, air reverses the path it used to enter. expiration. To CIRCULATORY SYSTEM The circulatory system is a transport system for many substances, most notably, blood. Blood is essentially made up oftwo parts: cells and plasma. Blood is a yellowish fluid that suspends the cells. It is similar to the broth in chicken noodle soup; it provides a liquid for the cells and other nutrients. Plasma is about 55% of total blood volume and carries important dissolved salts, water, fats and amino acids. plasma (to the heart, depleted) oXygen Blood cells can be one ofthree main types: red blood cells, white blood cells or platelets. are responsible for transporting oxygen. They contain an iron rich protein called hemoglobin, which gives these cells their red color. Red blood cells are the most attack harmful microorganisms (bacteria, viruses or Figure 4.3 Circulatory System parasites) and aid in immunity. Platelets are blood cells that form clots. Platelets, along with white blood cells, stop the bleeding at the site of a wound and eventually lead to the formation of a scab. Red . Circulatory System ‘ems common type blood cells of blood cell. White blood cells The heart is the pump of the circulatory system. It is a hollow muscular organ located between the lungs. It has four chambers that perform two primary functions. The heart: . ! . collects deoxygenated (without oxygen) blood from the body and pumps it to the lungs, and then... collects oxygenated blood from the lungs and pumps it throughout the body. . The respiratory system and circulatory system work closely together, because your body needs to take in oxygen and send it to your cells. . © . 0. 0 Q 39 The Human Body Oxygenated blood has passed through the lungs to pick up oxygen, and is ready to travel through the body to deliver the oxygen to cells. Oxygenated blood moves through the arteries. Arteries are the blood Vein vessels that carry blood “away” from the heart. Blood ThsueCells Capillaries vessels are hollow tubes that transport blood. There are Figure 4.4 Capillanes large vessels, like the aorta which measures roughly 2.5 cm, and small vessels, measuring 5 10 tm (that’s about 0.0005 cm). Really small blood vessels are called capillaries. The walls of a capillary are only one cell layer thick. This allows molecules and elements like oxygen, glucose and carbon dioxide to pass through. Capillaries are what actually bring the nutrients to individual cells. Capillaries ‘ . . . — Deoxygenated blood has traveled through the body and has already delivered oxygen to your cells via the capillaries. Deoxygenated blood travels in blood vessels called veins. Veins bring blood back to the heart and lungs. DIGESTIVE SYSTEM The digestive system breaks down food into smaller pieces that can be used by your cells. The digestive system is made up of several organs located in your mouth and inside your body. Some important organs involved in digestion include the esophagus, stomach, liver, small intestine and large intestine. Digestion can happen two ways: mechanically and chemically. Mechanical digestion occurs when food is physically broken into smaller pieces. Mechanical digestion occurs when you chew your food, and during movement of the stomach. Chemical digestion happens when chemicals inside your body break down food. One example of chemical digestion is stomach acid dissolving food. The digestive system works with the circulatory and excretory system to bring nutrients to cells and remove wastes. Co U) CD C1 CO Co C? w The mouth is where the digestive system begins. Food is placed inside the mouth, where your teeth, tongue, saliva and jaw muscles chew it. food is then swallowed, or ingested, down a tube called the esophagus. 0 -J Digestive System esophagus D I I- 0 z 0 0 Co 0. gall bladder— pancreas small intestines .e:::: large appendix E 0 0 0 0 Co (3 0 E Figure 4.5 Digestive System © 0. 0 0 40 Chapter 4 The esophagus is a tube of smooth muscle tissue that transports food to the stomach. The stomach is a bag-like organ that receives the large pieces of food from the mouth. The stomach chemically and mechanically breaks down large food pieces into much smaller pieces. The stomach has strong acids, a pH of 1 2, that chemically break down large food particles into much smaller pieces. In fact, acids inside the stomach are so strong, if placed on skin they could cause a chemical bum. In the first part of the small intestine (the duodenum), secretions from the pancreas neutralize stomach acids. Also in the duodenum, the liver secretes several chemicals that help break down fats. The small intestine is a hollow, highly folded tube that absorbs nutrients from food as it slowly moves the food to the large intestine. The last organ involved in digestion is the large intestine. The main ffinctjons of the large intestine are to absorb water from indigestible food and absorb vitamins released by bacteria living inside the large intestine. Another function ofthe large intestine is to compact solid wastes (indigestible food, also called feces). — h SKELETAL SYSTEM Skeletal System The skeletal system includes skull r.— Ije e and bones, cartilage, tendons sternum : scapula-_., ligaments. The skeletal system k— humerus jz provides support and structure b’ A ! :- veraI for the body. This is column racsa accomplished through the use of :—-carpaLs sacium inetacarpa1s / bones. Bones are an organ made 3 1 ‘phalanges \ pelvic girdle up of hard connective tissues i i tèmur 1 (mostly of calcium phosphate). ¶; -_patella Skeletal muscle attaches to bones to allow for movement. inetarsals Bones are also a source of phalanges -‘I calcium for other organs in our Figure 4.6 Skeletal System bodies. Calcified bone tissue renews itselfperiodically. When old bone breaks down, calcium and phosphorus move into the bloodstream and are able to be used in other ways. ,. 1L 4W - • % ‘ ‘ •1 ! - - - , :: • I ( . I ) A place where two bones join is called a joint. Joints allow your skeleton to move. Tough fibrous tendons attach muscles to bones and allow muscles to “pull” the bones in different directions. Ligaments are a band of dense, fibrous connective tissues that connect one bone to another. Ligaments function to stabilize joints. Cartilage, a tough connective tissue, is found at mostjoints. Injoints, cartilage softens movement between two bones. This allows a smooth, gliding action as the bones move past one another. In other body organs, like your ear or nose, firm yet flexible cartilage forms the main 41 The Human Body support structure. Cartilage lacks blood vessels resulting in a slow rate of repair, injury to certain cartilaginous tissues often results in lifelong diseases. This is particularly true ofknee or back cartilage injury. Joints are classified by the type of movement they allow and the types of tissues they have. The most commonly accepted types of joints are fixed, hinge, pivot, gliding and ball-and-socket. Fixedjoints, like in your skull, do not move but serve to absorb shock while protecting sensitive tissues underneath. Hinge joints, like your knee, allow for two directional nIovement and move like a door hinge. Pivot joints, like your elbow, allow for rotational movement around 1 80° axes. Gliding joints, like your wrists, allow slightly more rotational movement than pivot joints Figure 4.7 Synovial Joint and function as two bones glide past one another. The movement allowed by this joint type is defined by the shape ofthe bones involved. A ball-and-socketjoint, like your shoulder, allows the most freedom of movement and permits bones to rotate a full 360°. Can you name another ball-and-socket joint? Right your hip! Figure 4.7 shows a typical synovial joint, the most common moveablejoint. It is called a synovialjoint because ofthe synovial tissues located in and around it. An example of a synovialjoint is your knee. — IMMUNE SYSTEM The immune system is a collection of cells and tissues that defend the ;NKS human body against invaders. The immune system works with your ABCO8O dasese skm, respiratory system and digestive system to prevent disease. It consists of the lymphatic system, spleen, tonsils, thymus and bone marrow. Bone marrow makes leukocytes, white blood cells, which defend against infection and disease. F.., Sc In In c.,1 In In Iw4grqwLw ..... ui .. . 0 aD 0 z 0 C Figure 4.8 White Blood Cell > C E 0 0 0 0 to C U E © 0) 0. 0 0 : 42 Chapter 4 LYMPHATIC SYSTEM The lymphatic system is a network of the parts of the immune system. It consists of lymph vessels, lymph and lymphoid tissues (i.e. lymph nodes, tonsils, thymus and spleen). Lymph vessels transport lymph. Lymph is composed of tissue fluid and white blood cells. Tissue fluid is fluid that surrounds cells. It is made up of water,. small molecules and lymph cells. Lymphatic System Lymph nodes filter lymph fluid and prevent Figure 4.9 Lymphatic System foreign particles and microorganisms from entering the bloodstream. As the lymphatic system fights these invaders, lymph nodes can become swollen and sore. The lymphatic system also plays a role in returning fluid to blood. Lymph vessels do not have a pump (the heart) like arteries do. They operate like veins, relying on muscle contractions to push fluid throughout the body. Exercise helps keep lymph moving. This is one reason why people who regularly exercise seem to be sick less often! MUSCULAR SYSTEM The muscular system is used to move the body, help circulate blood and move food through the digestive system. The three types of muscular tissue that accomplish these tasks are skeletal, cardiac and smooth. Skeletal muscle tissue is attached to bones by tendons. Skeletal muscles, also called voluntary muscle, move the body. Voluntary muscle tissues are under the complete control ofthe organism; you decide when to move your arms and legs. Cardiac muscles are found only in the heart. These are a type of involuntary muscle. Involuntary muscles contract automatically. You don’t have to think about making your heart beat; it just happens! Mother type of involuntary muscle tissue is smooth muscle. Smooth muscle is found in many organs like the esophagus, stomach and intestines. 43 The Human Body NERVOUS SYSTEM The nervous system is the control and communication network of the body. It detects and responds to stimuli both inside and outside the body. The five senses (smell, touch, taste, sight and hearing). are controlled by this system. A nerve is a bundle of nerve cells or neurons. Neurons carry information from one place to another. Nervous System brain spinal cord The two main parts of the nervous system are the central nervous system (CN$) and the peripheral nervous system. The central nervous system is made up of the brain and spinal cord. The CNS is the main control center Figure 4.10 Nervous System for the human body. The peripheral nervous system consists of all other parts of the nervous system. The peripheral nervous system carries nerve impulses from the brain and spinal cord to the body and back to the brain. The nerves that detect heat in your fingers exemplify the peripheral nervous system. . The brain is the most important and complex human organ. A complete (Bodysensesorientation, discussion of the brain is beyond the visualand apaUni percepUon) scope of this text; however, it is Occipft& Lobe important to have a basic Vialon) Temporal Lobe understanding of how the brain (Hearing, music, understanding Cerebellum speech menroryfornomverbal functions. It serves as the control )Muac)e coordination) events) Brain Stern Spinal Cord Maintain homeostasis: center for the entire human body. It a.blood pressure b. heartbeat regulates behavior, blood chemistry, mood, growth, heart rate, sleep Figure 4.11 Parts ofthe Human Brain cycles, reproduction orjust about any other bodily function you can think of. The brain has a complex network of nerves (at least 23 billion neurons) that interact closely with the spinal cord and sensory neurons. The brain sends messages down the spinal cord, a long thin bundle of nerves running the length of the vertebral column, to different parts of the body. The main function of the spinal chord is to transport messages from the brain to the body’s nerves and vice versa. The brain receives information from your senses (eyes, nose, etc.) and processes this information to cause appropriate action. While your eyes merely perceive the words on the page, your brain allows you to understand their meaning. Internal body signals are also perceived by the brain. Changes in blood chemistry, like a buildup of CO2 during exercise, are detected by the brain. The brain then sends signals to the rest of the body to increase both the heart and breathing rate. Language Area Judgment. initiation, IHandukills sensory. reading. abstract thought, speech) writing, numbers) . ‘ Co L() Co c1 CO Co op LU 0 -j a. I- 0• z 0 0 CC E 0 0 0 0 CC U CC E © > a- 0 0 44 Chapter 4 EXCRETORY SYSTEM The excretory system removes wastes from the body. The lungs and skin release some wastes through respiration and sweating, but the majority of metabolic wastes are removed through the urinary tract. The urinary tract consists of the kidneys, ureters, bladder and urethra. The excretory system removes wastes from cells in the body. REPRODUCTiVE SYSTEM The Urinary Tract aorta ‘ena cava kidney 1.111::. ureters ( bladder urethra Reproduction is necessary for the continuation ofa species. figure 4.12 The Uñnaiy Tract Human reproduction involves two parents: a male and a female. The reproductive system allows humans to reproduce. The organs in the reproductive system are different for males and females. In males, the reproductive system is composed of the testes and the penis. In females, the reproductive system includes the ovaries, uterus, vagina and breasts. Males have two testes glands that produce testosterone, the male sex hormone. Upon sexual maturity, the amount of testosterone increases, and sperm are produced in the testes. Sperm are male sex cells, or gametes, that move via flaggeflum. Males can produce sperm throughout their lifetime. Sperm leave the body, in semen, through the urethra. The urethra is the opening the head of the penis. — females produce ova, or eggs, which are housed in two ovaries. Upon sexual maturity, one ovum forms approximately every 28 days, when it is released from the ovary and travels along the fallopian tube on its way to the uterus. The uterus is a hollow organ that provides a place for the embryo (an embryo is a developing baby) to develop. During pregnancy, the uterus more than doubles in size. g If sperm and egg unite, fertilization occurs, resulting in a zygote. The zygote develops into a fetus in the uterus until, finally, a baby is born. The human female feeds the infant with milk produced by mammary glands in the breasts. female Reproductive System Figure 4.13 Female Reproductive System Activity Research the different organ systems using textbooks or the Internet. Determine which body system (circulatory, digestive, skeletal, respiratory, immune, lymphatic, muscular, nervous, excretory or reproductive) you could live without. reparedtodefendyourposffionwithevidenceandJorlogical reasoning. 45 The Human Body CHAPTER 4 REVIEW 1. What is one major function ofthe lymphatic system? A B C B transporting oxygenated and deoxygenated blood providing support and structure for the body transmitting information from the environment to the brain preventing foreign particles from entering the bloodstream 2. How does the stomach aid in digestion? A B C B It mechanically breaks down fats. It chemically and mechanically breaks down foods. It mechanically breaks down sugars. It chemically breaks down proteins. 3. The diaphragm contracts to A B C B force air into the lungs. force air into and out of the lungs. move the stomach, assisting in the mechanical breakdown of food. support the spinal column. 4. What is the main job of the respiratory system? A B C B delivering carbon monoxide to the important parts of the body pumping blood to the capillaries taking in oxygen needed for respiration taking in carbon dioxide and delivering it to the cells 5. What are the main components of the circulatory system? A B C B bone marrow, ligaments and tendons i heart, veins, arteries and capillaries brain, spinal cord and neurons stomach, esophagus and small intestine ,