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Lesson 2 - Organ Systems of the Human Body

Student Performance Objectives
1. List and briefly explain the basic functions of the human body's 11 organ systems.
2. List and briefly describe the basic function of each organ within the organ systems.
3. Demonstrate proficiency in organ identification using a human torso model.
4. Demonstrate proficiency in locating animations of major organ functions utilizing the Internet.

Lesson Outline
A. The Organ Systems - 11 in total.
    1. Integumentary: skin and associated parts - hair, sweat glands, sebaceous glands, nails, and receptors for temperature, pain, and touch. Skin is also known as the integument. The skin's upper layer that we see is the epidermis; the underlying skin layer is the dermis. Among the many functions of the integumentary system are protection from invading microorganisms, protection from dehydration, providing sensory awareness and the synthesis of vitamin D.
    2. Skeletal: the bones of the body - axial (cranium, vertebral column, sternum and rib cage) and appendicular skeleton (pectoral girdle and the arms and the pelvic girdle and the legs). The prefix osteo refers to bone. An osteocyte is a bone-formng cell. Osteology is the study of bones. The skeletal system protects our softer internal organs, produces erythrocytes (red blood cells) in red marrow, and acts as a mineral storage area.
    3. Muscular: striated muscles compose the voluntary muscles that attach to the skeleton and help to move you from place to place. The prefix myo refers to muscle. A myocyte is a muscle cell.
Smooth muscle is found composing the walls of the body's internal, hollow organs, like the stomach and other digestive organs, and the blood vessels. Contractions of smooth muscles lead to movements of food and wastes through the digestive tract, the secretion of products from exocrine glands, and the squeezing of the blood within the blood vessels raising blood pressure. Cardiac muscle composes the wall of the heart and is responsible for the heart beat which is the heart pumping blood. Typically, when a biologist refers to the "skeletal system" they are only referring to the striated muscles and their attachments to the skeletal system and to other body tissues. Smooth muscles are taken up in the section on the autonomic nervous system (ANS) and cardiac muscle is studied in the section on the heart.
    4. Nervous: brain, spinal cord, peripheral nerves, and receptors. Prefixes like neuro and cerebro refer
to the nervous system as in a neuron (nerve cell) and a cerebrovascular accident (a stroke). The nervous system coordinates receives our sensory input from our receptors, analyzes incoming information, and produces our responses, often movements, by activating our skeletal muscles. The nervous system gives rise to the mind which thinks and has a sense of identity.
    5. Endocrine: the ductless glands - pituitary, thyroid, adrenals and many others. The hormones produced by the endocrine glands regulate cellular chemistry throughout the body. Examples of endocrine activities are regulating growth in height in children, determining our overall rate of burning up food and so regulating our weight, and the control or the blood levels of many chemicals including glucose, sodium, chloride and potassium.
    6. Digestive: the gastrointestinal tract and associated organs - liver, gall bladder, and pancreas. Prefixes like gastro (stomach) and words like hepatic (liver) refer to regions of the digestive system. This system chemically digests our food into nutrients that can be absorbed, circulated to our cells and utilize for growth, repair, and maintenance of the body.
    7. Cardiovascular: heart and blood vessels. The prefix cardio refers to heart. The cardiovascular system pumps blood to the tissues that need nutrients and oxygen and need to release their waste products. The system also pumps blood to the lungs where oxygen from the air is picked up by the hemoglobin within the erythrocytes and where carbon dioxide is released from the blood into the air.
    8. Lymphatic and Immune: lymphatic channels, thymus lymph nodes and related lymphatic structures. The immune system is under intense study at this time and is responsible for protecting us from outside invaders (e.g., all types of microorganisms) and from inside "mistakes" such as the development of cells growing without limits - cancer cells. Weaknesses in the immune system are believed to be the cause of many infectious diseases and to be the reason we fail to weed-out and destroy cancer cells.
    9. Respiratory: lungs and the respiratory tract - mouth, pharynx, larynx, trachea and other air passages. The prefix pneumo (as in pneumonia) refers to the respiratory system. The respiratory system is responsible for ventilating the lungs, i.e., getting air in and out of the lungs. The system is also responsible for removing acid from the blood as carbon dioxide is released into the air from the blood.
  10. Urinary: kidneys and the urinary tract - ureters, urinary bladder and urethra. The word renal refers to the kidneys. The urinary system removes many waste products from the blood and dissolves them in water that is urinated out of the body. The system also regulates the concentration of ions like sodium and potassium in the blood and the concentrations of many other substances whose precise concentration is critical for cellular health.
  11. Reproductive: ovaries and testes and associated ducts and organs. The reproductive system of the male produces, matures and delivers sperm to the female genital tract. The female reproductive system produces and ovulates eggs. The female's uterus is the site of the development of the next generation of humans.

B. Listing major organs within each system.
This is an exercise for you to carry out on your own- make a separate list of each of the body's 11 organ systems and see if you can list the major organs associated with each of the systems. Since this will probably be an essay question on the first quiz, you can practice outlining this fundamental information.

C. Overall function of each system.
As with section B, this is also an exercise for you to complete on your own - the detailed functioning of each of the body's organ systems is the subject of this entire website and your textbook, but you should have an idea of the overall functioning of each organ system before we get into the details. So, for instance, you should know that the major functions of the skeletal system are to provide support for the rest of the body, provide for movement at the joints, to give protection to softer tissues, and to support the formation of blood cells (hemopoiesis) in the interior marrow spaces of osseus tissue (bone). Many of the major functions of the organ systems are discussed above. You can find additional functions in your text and on-line.

D. Use of Torso models to identify the major organs of each system.
This is a laboratory exercise in which you observe and take apart the torso model of a human to get a fundamental idea of the placement and names of the body's major organs. You will do a dissection of a preserved rat to reinforce your understanding of the placement of body parts.

E. Use the Internet to find animations of:
    1. Beating heart:
    2. Contracting skeletal muscle:  
    3. Nerve impulses:
    4. Glandular secretion:
5. Endoscopy of the GI tract: Biomedical Terminology:  Define the terms. E.g.: cardiovascular refers to the heart and blood vessels;
digestive refers to the organs of the digestive system like the stomach and small intestine.


Biomedical Root Words: Relate each "root" word to an organ and then utilize the root in a word. E.g.: cardio refers to the heart and is part of the words cardiovascular and cardiomyopathy; cerebro refers to the part of the brain called the cerebrum and is part
of the word cerebrospinal as in cerebrospinal fluid.

cardio - heart
cerebro - cerebrum
gastro - stomach
hepatic - liver
myo - muscle
neuro - nerve or nervous system
osteo - bone
pneumo - respiratory
renal - kidney

Look over the useful prefixes and suffixes at