Digestive System Organs & their FunctionsMouth & Teeth- The mouth and teeth change food into a soft, moist mass through the processes ofchewing and adding saliva. This is the first step in the process of food digestion.Esophagus- The esophagus is a tube-shaped structure that has muscular rings around it. Theesophagus transports food from the mouth to the stomach.Stomach- The stomach is a muscular sac. It releases acid, which breaks down food into smallerparts. The stomach also mixes the food, which helps to break it down.Small intestine- The small intestine is a long tube-like organ that is lined with muscle and specialcells. These cells absorb the nutrients from digested food into the blood. Muscles in the intestinewall help food to move through to the large intestine.Large intestine- Like the small intestine, the large intestine is tube-shaped and lined with muscle. Thecells in the wall of the large intestine absorb water from the partially digested food. They absorbabout a gallon and a half of water daily. Also, bacteria in the large intestine help break down some ofthe remaining undigested materials. The material that cannot be digested moves out of the body aswaste.Liver- The liver is the largest internal organ of the human body. It makes a chemical called bile, whichhelps to break down food, especially fats. The liver is located beside the stomach and is mostly onthe right side of the body.
Circulatory System Organs & their FunctionsCirculatory System Organs & their FunctionsVeins—Veins are the larger blood vessels that carry blood back to the heart after itsoxygen has been carried to body tissues. Veins are normally drawn blue in diagrams.Arteries—Arteries move blood that is rich in oxygen away from the heart. The pressurefrom the heart’s pumping action keeps this blood moving in the right direction. Arteriesare normally drawn red in diagrams.Heart—The heart is made up of four sections, or chambers. Two of them, the right atriumand the right ventricle, push blood returning from the body to the lungs. The othertwo, the left atrium and the left ventricle, get oxygen-rich blood from the lungs and send itback out to the body. The pulse you can feel in your wrist is the blood hitting the walls ofthe artery there with each pump of the heart.Capillaries—Capillaries are tiny blood vessels that carry oxygen to tissues. They can onlybe seen under a microscope because they are about one-tenth the width of a humanhair. Capillaries have thin walls that allow oxygen and nutrients from the blood to movethrough them to the tissues. Carbon dioxide and other wastes leave the body cells, crossthrough the capillary walls, and enter the blood for the trip back to the heart and lungs.
Nervous System Components & their FunctionsBrain—The brain is the control center of the body. Itcontrols body functions and helps humans torespond to conditions and events in theenvironment.Spinal cord—The spinal cord carries information toand from the brain. Nerves reach from the spinalcord to the rest of the body. The spinal cord isprotected by the bones of the spine.Nerve cells—Nerve cells have long fibers that reachto different parts of the body. These nerve cellscollect information from the environment and sendit through the spinal cord to the brain. The brainthen processes the information and comes up withthe proper response.
Respiratory System Organs & their FunctionsNose—The nose is lined with mucus and tiny hairs. The hairs trap particles, such as dirtand bacteria. The mucus adds moisture to the air and also helps trap particles.Trachea—The trachea, or windpipe, is a tube that allows air to pass to the lungs. It is linedby a mucous membrane that traps particles that were able to travel through thenose. Close to the lungs, the trachea divides into two branches called the bronchial tubes.Bronchial tubes—Each of the bronchial tubes carries air into one of the lungs. Once insidethe lung, the bronchial tubes divide into smaller and smaller tubes that eventually lead tosmall air sacs.Air Sacs—The air sacs are lined with a thin layer of skin cells. Gases like oxygen andcarbon dioxide move through the walls of the air sacs and into capillaries that surroundthem. Air sacs are too small to be seen without a microscope. There are about 480 millionair sacs in each human lung.Diaphragm—The diaphragm is a large muscle that sits just below the lungs. When itflexes, it causes the lungs to expand and take in more air. When the diaphragmrelaxes, air moves out of the lungs.
The Skeletal SystemThe skeleton is a human bodysystem that is made up of over200 bones. Every time you walkto school or stand up from yourdesk, you are using yourskeleton.The bones of theskeleton are important for:•providing support for musclesand other body tissues•protecting organs, such as thebrain, heart, and lungs•allowing movement, such aswalking
The Muscular System•Muscles work with bones andjoints to allow us to move.•The human body has more than650 tough, elastic pieces of tissuecalled muscles. Muscles attach tothe bones of the skeletal system andallow the body to move.Muscle Movement•The pull of a muscle occurs whenthe muscle contracts and becomeshorter and tighter. Often muscleswork in pairs so thatone relaxes while theother tightens.
The Excretory SystemThe excretory system collects wastes from cells and empties the wasteoutside of the body. The human excretory system includes the lungs, sweatglands in the skin, and the urinary system.Lungs and Sweat Glands•The human body creates carbon dioxide gas as a waste product duringcellular respiration. The lungs remove this waste from the body when aperson exhales.•Sweat glands in the skin can remove excess water and salt from the body.The Urinary SystemThe urinary system removes waste products from the blood and excretesthem in the form of urine. The urinary system is made up of thekidneys, ureter, urinary bladder, and urethra.The kidneys filter blood and send wastes in the form of urine throughmuscular tubes known as ureters into the bladder. The bladder then storesthe urine until it can be excreted to the outside of the body through a smalltube called the urethra.
The Endocrine SystemThe main function of the endocrine system is to help the body regulate itself by wayof hormones, or chemical messengers, that are produced by glands.These hormones enter the bloodstream and regulate many body processes, includinggrowth and development, metabolism, and reproduction.The pancreas is a gland organ that is part of the endocrine system. It has two mainfunctions. It releases hormones, such as insulin, which help keep blood sugar levels even. Italso produces digestive enzymes, which it then sends into the small intestine in order tohelp break down food.
Human Body Structures•The eyes sense light, which makes itpossible for people to see. Sightallows people do describe theobjects around them in differentways, such as through anobjects color or its levelof brightness.•The nose senses the smell ofodors. Odors move through theair, and the nose collects thisair. Odors can be described by termssuch as sweet, musty, fruity, or sour.•The ears gather information aboutthe noises in the air. Sound travelsthrough the air, and the ears captureit. This is how people hear. Thesounds people hear can be describedin ways such as loud or soft and high-pitched or low-pitched.
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Let’s see what you remember with a labeling activity!
Use your text tool to label:EsophagusLiverStomachSmall IntestineLarge Intestine
Use your text tool to label:NoseTracheaBronchial tubesLungsDiaphragm
Use your text tool to label:VeinsArteriesHeart