{"id":4720,"date":"2020-04-01T17:24:17","date_gmt":"2020-04-01T17:24:17","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/9-4-human-organs-and-organ-systems-3\/"},"modified":"2023-11-30T18:48:48","modified_gmt":"2023-11-30T18:48:48","slug":"9-4-human-organs-and-organ-systems-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/9-4-human-organs-and-organ-systems-3\/","title":{"raw":"7.5 Human Organs and Organ Systems","rendered":"7.5 Human Organs and Organ Systems"},"content":{"raw":"

<\/p>\r\n\r\n\r\n[caption id=\"attachment_2903\" align=\"aligncenter\" width=\"300\"]\"\" Figure 7.5.1\u00a0 I \"Heart\" You. <\/em>[\/caption]\r\n

I \"Heart\" You<\/h1>\r\nYou've probably heard one song or another about the heart. Heartache, heartbreak... it's all related to love. But did you ever wonder why<\/em>\u00a0we associate love with the\u00a0heart?\r\n

The\u00a0heart\u00a0was once thought to be the center of all thought processes, as well as the site of all emotions. This notion may have stemmed from very early anatomical dissections that found many nerves traced to the region of the heart. The fact that the heart may start racing when one is excited or otherwise emotionally aroused may have contributed to this idea, as well. In\u00a0reality, the heart is\u00a0not<\/em> the organ that controls thoughts or emotions. The organ that controls those functions, in actuality, is the brain. In this section, you\u2019ll be introduced to the heart, brain, and other major organs of the human body.<\/p>\r\n\r\n

Human Organs<\/h1>\r\n

An [pb_glossary id=\"2803\"]organ[\/pb_glossary] is a collection of [pb_glossary id=\"2801\"]tissues[\/pb_glossary] joined in a structural unit to serve a common function. Organs exist in most multicellular organisms, including humans, other\u00a0animals, and plants. In single-celled organisms (such as [pb_glossary id=\"2588\"]bacteria[\/pb_glossary]), the functional equivalent of an organ is an organelle.<\/p>\r\n\r\n

Tissues in Organs<\/h2>\r\n

Although organs consist of multiple tissue types, many organs are composed of a main tissue that is associated with the organ\u2019s major function, along with other tissues that play supporting roles. The main tissue may be unique to that specific organ. For example, the main tissue of the heart is cardiac muscle, which performs the heart\u2019s major function of pumping\u00a0blood\u00a0and is found only in the heart. The heart also includes nervous and connective tissues that are required for it to perform its major function. For example, nervous tissues control the beating of the heart, and connective tissues make up heart valves that keep blood flowing in just one direction through the heart.<\/p>\r\n\r\n

Vital Organs<\/h2>\r\n

The\u00a0human body\u00a0contains five organs that are considered vital for survival: the heart, brain,\u00a0kidneys, liver, and lungs. The locations of these five organs \u2014 and several other internal organs \u2014 are shown in the figure below. If any of the five vital organs stops functioning and medical intervention is not readily available,\u00a0the organism's death will be\u00a0imminent.<\/p>\r\n\r\n

    \r\n \t
  1. The\u00a0heart<\/strong>\u00a0is located in the center of the chest, and its function is to keep\u00a0blood\u00a0flowing through the body. Blood carries substances to the\u00a0cells\u00a0they need. It also carries wastes away from cells.<\/li>\r\n \t
  2. The\u00a0brain<\/strong>\u00a0is located in the head and functions as the body\u2019s control center. It is the seat of all thoughts, memories, perceptions, and feelings.<\/li>\r\n \t
  3. The two\u00a0kidneys<\/strong>\u00a0are located in the back of the abdomen on either side of the body. Their function is to filter\u00a0blood\u00a0and form urine, which is excreted from the body.<\/li>\r\n \t
  4. The\u00a0liver<\/strong>\u00a0is located on the right side of the abdomen. Its functions\u00a0include filtering blood, secreting bile that is needed for digestion, and producing\u00a0proteins\u00a0necessary for blood clotting.<\/li>\r\n \t
  5. The two\u00a0lungs<\/strong>\u00a0are located on either side of the upper chest. Their main function is exchanging oxygen and carbon dioxide with the blood.<\/li>\r\n<\/ol>\r\n[caption id=\"\" align=\"aligncenter\" width=\"400\"]\"\" Figure 7.5.2 Human anatomy\/ Internal organs.\u00a0<\/em>[\/caption]\r\n

    Use this shadow diagram of human anatomy to locate the five organs described above: heart, brain,\u00a0kidneys, liver, and lungs. Do you know the functions of any of the other organs in the diagram?<\/p>\r\n\r\n

    Human Organ Systems<\/h1>\r\n

    Functionally related organs often cooperate to form whole organ systems. The 12 diagrams in Figure 7.5.3 show 11 human organ systems, including separate diagrams for the male and female reproductive systems. Some of the organs and functions of the organ systems are identified. Each system is also described in more detail in the text that follows. Most of these human organ systems are also the subject of separate chapters in this book.<\/p>\r\n\r\n

    \r\n

    [h5p id=\"531\"]<\/p>\r\nFigure 7.5.3 Human Organ Systems. These diagrams represent 11 human organ systems and show some of their organs and functions. The male and female reproductive systems are shown separately because of their significant differences.<\/em>\r\n\r\n<\/div>\r\n

    \r\n

    Integumentary System<\/span><\/p>\r\n\r\n<\/div>\r\n

    Organs of the [pb_glossary id=\"2905\"]integumentary system[\/pb_glossary] include the skin, hair, and nails. The skin is the largest organ in the body. It encloses and protects the body and is the site of many sensory receptors. The skin is the body\u2019s first defense against pathogens, and it also helps regulate body\u00a0temperature\u00a0and eliminate wastes in sweat.<\/p>\r\n\r\n

    Skeletal System<\/h2>\r\n

    The\u00a0[pb_glossary id=\"2906\"]skeletal system[\/pb_glossary]\u00a0consists of\u00a0bones,\u00a0joints, teeth. The bones of the skeletal system are connected by tendons, ligaments, and cartilage. Functions of the skeletal system include supporting the body and giving it shape. Along with the muscular system, the skeletal system enables the body to move. The bones of the skeletal system also protect internal organs, store calcium, and produce red and white blood\u00a0cells.<\/p>\r\n\r\n

    Muscular System<\/h2>\r\n

    The [pb_glossary id=\"2907\"]muscular system[\/pb_glossary] consists of three different types of\u00a0muscles, including\u00a0skeletal muscles, which are attached to\u00a0bones\u00a0by tendons and allow for voluntary movements of the body. Smooth muscle tissues control the involuntary movements of internal organs, such as the organs of the\u00a0digestive system, allowing food to move through the system. Smooth muscles in\u00a0blood vessels\u00a0allow vasoconstriction and vasodilation, thereby helping to regulate body\u00a0temperature. Cardiac muscle tissues control the involuntary beating of the heart, allowing it to pump blood through the blood vessels of the\u00a0cardiovascular system.<\/p>\r\n\r\n

    Nervous System<\/h2>\r\n

    The\u00a0[pb_glossary id=\"2908\"]nervous system\u00a0[\/pb_glossary]includes the brain and spinal cord \u2014 which make up the\u00a0central nervous system\u00a0\u2014 and nerves that run throughout the rest of the body, making up the\u00a0peripheral nervous system. The nervous system controls both voluntary and involuntary responses of the human organism, and also detects and processes sensory information.<\/p>\r\n\r\n

    Endocrine System<\/h2>\r\n

    The\u00a0[pb_glossary id=\"5985\"]endocrine system[\/pb_glossary]\u00a0is made up of glands that secrete hormones into the blood, which then carries hormones throughout the body. Endocrine hormones are chemical messengers that control many body functions, including metabolism, growth, and sexual\u00a0development. The master gland of the endocrine system is the pituitary gland, which produces hormones that control other\u00a0endocrine glands. Some of the other endocrine glands include the pancreas, thyroid gland, and adrenal glands.<\/p>\r\n\r\n

    Cardiovascular System<\/h2>\r\n

    The\u00a0[pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary]\u00a0(also called circulatory system) includes the heart, blood, and three types of\u00a0blood vessels: arteries, veins, and capillaries. The heart pumps blood, which travels through the blood vessels. The main function of the cardiovascular system is transport. Oxygen from the lungs and nutrients from the\u00a0digestive system\u00a0are transported to\u00a0cells\u00a0throughout the body. Carbon dioxide and other waste materials are picked up from the cells and transported to organs (such as the lungs and kidneys) for elimination from the body. The cardiovascular system also equalizes body\u00a0temperature\u00a0and transports endocrine hormones to cells in the body where they are needed.<\/p>\r\n\r\n

    Lymphatic System<\/h2>\r\n

    The[pb_glossary id=\"2911\"]\u00a0lymphatic system[\/pb_glossary]\u00a0is sometimes considered part of the immune system. It consists of a network of lymph vessels and ducts that collect excess fluid (called lymph) from extracellular spaces in tissues and transport the fluid to the bloodstream. The lymphatic system also includes many small collections of tissue, (called lymph nodes) and an organ called the spleen, both of which remove pathogens and cellular debris from the lymph or blood. In addition, the thymus gland in the lymphatic system produces some types of white blood cells (lymphocytes) that fight infections.<\/p>\r\n\r\n

    Respiratory System<\/h2>\r\n

    Organs and other structures of the\u00a0[pb_glossary id=\"2912\"]respiratory system[\/pb_glossary]\u00a0include the nasal passages, lungs, and a long tube called the trachea, which carries air between the nasal passages and lungs. The main function of the respiratory system is to deliver oxygen to the blood and remove carbon dioxide from the body. Gases are exchanged between the lungs and blood across the walls of capillaries lining tiny air sacs (alveoli) in the lungs.<\/p>\r\n\r\n

    Digestive System<\/h2>\r\n

    The [pb_glossary id=\"5969\"]digestive system[\/pb_glossary] consists of several main organs\u00a0\u2014\u00a0including the mouth, esophagus, stomach, and small and large intestines \u2014 that form a long tube called the gastrointestinal (GI) tract. Food moves through this tract, where it is digested. Its nutrients are then absorbed, and its waste products are excreted. The digestive system also includes accessory organs (such as the pancreas and liver) that produce\u00a0enzymes\u00a0and other substances needed for digestion, but through which food does not actually pass.<\/p>\r\n\r\n

    Urinary System<\/h2>\r\n

    The\u00a0[pb_glossary id=\"2914\"]urinary system[\/pb_glossary]\u00a0is\u00a0part of the\u00a0[pb_glossary id=\"5999\"]excretory system[\/pb_glossary], which\u00a0removes\u00a0wastes from the body. The\u00a0urinary system\u00a0includes the pair of kidneys, which filter excess\u00a0water\u00a0and a waste product (called urea) from the blood and form urine. Two tubes called ureters carry the urine from the kidneys to the urinary bladder, which stores the urine until it is excreted from the body through another tube\u00a0called\u00a0the urethra. The kidneys also produce an\u00a0enzyme\u00a0called renin and a variety of hormones. These substances help regulate\u00a0blood pressure, the production of red blood cells, and the balance of calcium and phosphorus in the body.<\/p>\r\n\r\n

    Male and Female Reproductive Systems<\/h2>\r\n

    The [pb_glossary id=\"2916\"]reproductive system[\/pb_glossary] is the only body system that differs substantially between males and females. Both male and female reproductive systems produce sex-specific sex hormones (testosterone in males, estrogen in females) and gametes (sperm\u00a0in males, eggs in females). However, the organs involved in these processes are different. The\u00a0male reproductive system\u00a0includes the epididymis, testes, and penis. The\u00a0female reproductive system\u00a0includes the uterus, ovaries, and mammary glands. The male and female systems also have different additional roles. For example, the male system has the role of delivering gametes to the female reproductive tract, whereas the female system has the roles of supporting an embryo and fetus until birth and also producing milk for the infant after birth.<\/p>\r\n\r\n

    Feature: Human Biology in the News<\/h1>\r\n

    Organ transplantation has been performed by surgeons for more than six decades, and you\u2019ve no doubt heard of people receiving heart, lung, and kidney transplants. However, you may have never heard of a penis transplant. The first U.S. penis transplant was performed in May 2016 at Massachusetts General Hospital in Boston. The 15-hour procedure involved a team of more than 50 physicians, surgeons, and nurses. The patient was a 64-year-old man who had lost his penis to\u00a0cancer\u00a0in 2012. The surgical milestone involved grafting microscopic\u00a0blood vessels\u00a0and nerves of the donor organ to those of the recipient. As with most transplant patients, this patient will have to take immunosuppressing drugs for the rest of his life so his immune system will not reject the organ. The transplant team said that their success with this transplant \u201cholds promise for patients with devastating genitourinary injuries and disease.\u201d They also hope their experiences will be helpful for gender reassignment surgery.<\/p>\r\nSee the Johns Hopkins Medicine video below for a summary of how the penile and scrotum transplant procedure was carried out:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=NwHxIhP7zTE\r\n

    World's First Total Penile and Scrotum Transplant | Johns Hopkins Medicine, 2018.<\/p>\r\n\r\n

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    7.5\u00a0Summary<\/span><\/h1>\r\n<\/header>\r\n
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