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The human body is an amazing structure consisting of nearly 100 trillion cells, the basic unit of life. These cells are organized biologically to eventually form the whole body. To understand the human body, it is necessary to understand how its parts are put together and how they function. The human anatomy and physiology are the study of the structure and function of the human body. In this part, you will have an overall understanding of the human organism.
☆ Define anatomy and explain the importance of understanding the relationship between structure and function.
☆ Define physiology and state two major goals of physiology.
☆ Describe six levels of organization of the body.
☆ List the major organ systems and relate various organs to their respective systems.
☆ Describe the major trunk cavities.
☆ Define homeostasis and explain why it is important.
☆ Define metabolism and the two processes of metabolism.
Anatomy is the scientific discipline that investigates the structure of the body. The word“anatomy” means dissecting, or cutting apart and separating the parts of the body for study. Anatomy covers a wide range of studies, including the structure of body parts, their microscopic organization, and the processes by which they develop. In addition, anatomy examines the relationship between the structure of a body part and its function. Just as the structure of a hammer makes it well suited for pounding nails, the structure of body parts allows them to perform specific functions effectively. For example, bones can provide strength and support because bone cells surround themselves with a hard, mineralized substance. Understanding the relationship between structure and function makes it easier to understand and appreciate anatomy.
Physiology is the scientific discipline that deals with the processes or functions of living things. It is important in physiology to recognize structures as dynamic rather than static,or unchanging. The major goals of physiology are to understand and predict the body’s responses to stimuli, and to understand how the body maintains conditions within a narrow range of values in the presence of a continually changing environment.
Physiology is divided according to the organisms involved or the levels of organization within a given organism. Human physiology is the study of a specific organism, the human,whereas cellular and systemic physiology are examples of physiology that emphasize specific organizational levels.
The body can be studied at six structural levels: the chemical, cell, tissue, organ, organ system, and organism.
The structural and functional characteristics of all organisms are determined by their chemical makeup. The chemical level of organization involves interactions among atoms and their combinations into molecules. The function of a molecule is related intimately to its structure. For example, collagen molecules are strong, ropelike fibers that give skin structural strength and flexibility. With old age, the structure of collagen changes and the skin becomes fragile and is torn more easily.
Cells are the basic structural and functional units of organisms, such as plants and animals. Molecules can combine to form organelles (Figure 1-1),which are the small structuresthat make up cells. For example,the nucleus contains the cell’s hereditary information and mitochondria manufacture adenosine triphosphate (ATP), which is a molecule used by cells for a source of energy. Although cell types differ in their structure and function, they have many characteristics in common.Knowledge of these characteristics and their variations is essential to a basic understanding of anatomy and physiology.
Figure 1-1 A typical animal cell
A tissue is a group of similar cells and the materials surrounding them. The characteristics of the cells and surrounding materials determine the functions of the tissue. The many tissues that make up the body are classified into four primary tissue types: epithelial ,connective, muscular and nervous.
An organ is composed of two or more tissue types that together perform one or more common functions. The urinary bladder, skin, stomach, eye and heart are examples of organs.
An organ system is a group of organs classified as a unit because of a common function or set of functions. For example, the urinary system consists of the kidneys, ureters , urinary bladder and urethra . The kidneys produce urine, which is transported by the ureters to the urinary bladder, where it is stored until eliminated from the body by passing through the urethra. Usually the body is considered to have 11 major organ systems: integumentary , skeletal , muscular, lymphatic , respiratory , digestive , nervous, endocrine , cardiovascular , urinary and reproductive .
The coordinated activity of the organ systems is necessary for normal function. For example, the digestive system takes in and processes food, which is carried by the blood of the cardiovascular system to the cells of the other systems. These cells use the food and produce waste products that are carried by the blood to the kidneys of the urinary system, which removes waste products from the blood. Because the organ systems are so interrelated, dysfunction of one organ system can have profound effects on other systems.For example, a heart attack can result in inadequate circulation of blood. Consequently, the organs of other systems, such as the brain and kidneys, can malfunction .
An organism is any living thing considered as a whole, whether composed of one cell,such as a bacterium, or trillions of cells, such as a human. The human organism is a complex of organ systems that are mutually dependent on one another.
The organs that comprise most of the body systems are located in four cavities: cranial , spinal , thoracic , and abdominopelvic . The cranial and spinal cavities are within a larger region known as the dorsal (posterior) cavity.The thoracic and abdominopelvic cavities are found in the ventral (anterior) cavity. (Figure 1-2)
The dorsal cavity contains the brain and spinal cord: The brain is in the cranial cavity and the spinal cord is in the spinal cavity. The diaphragm divides the ventral cavity into two parts: the upper thoracic and lower abdominopelvic cavities.
Figure 1-2 Body cavities
The central area of the thoracic cavity is called the mediastinum . It lies between the lungs and extends from the sternum (breast bone) to the vertebrae of the back. The esophagus , bronchi , lungs, trachea , thymus gland and heart are located in the thoracic cavity. The heart itself is contained within a smaller cavity,called the pericardial cavity.
The thoracic cavity is further subdivided into two pleural cavities: The left lung is in the left cavity; the right lung is in the right cavity. Each lung is covered with a thin membrane called the pleura .
The abdominopelvic cavity is actually one large cavity with no separation between the abdomen and pelvis. To avoid confusion, this cavity is usually referred to separately as the abdominal cavity and the pelvic cavity. The abdominal cavity contains the stomach, liver, gallbladder , pancreas , spleen, small intestine , appendix and part of the large intestine. The kidneys are close to but behind the abdominal cavity. The urinary bladder, reproductive organs, rectum , remainder of the large intestine and appendix are in the pelvic cavity. (Figures 1-3, 1-4)
Figure 1-3 Organs of the abdominopelvic and thoracic cavities, anterior view
Figure 1-4 Organs of the abdominopelvic and thoracic cavities, posterior view
In addition to the cranial cavity, the skull also contains several smaller cavities. The eyes,eyeball muscles, optic nerves and lacrimal (tear) ducts are within the orbital cavity. The nasal cavity contains the parts that form the nose. The oral or buccal cavity encloses the teeth and tongue.
Homeostasis is the ability of the body to regulate its’ internal environment within narrow limits. Homeostasis is essential to survival: many of our body’s systems are concerned with maintaining the internal environment. Examples of homeostasis controls are blood sugar levels, body temperature, heart rate and the fluid environment of the cells.
Homeostasis works on a negative feedback mechanism. An example of how it operates is seen in maintaining our body temperature. Our normal body temperature is 98.6°F. Outside,on a very hot summer day, our body temperature rises. The hypothalamus in the brain detects this and sends signals to various organs and we start to sweat (sweating is a cooling process). As water is excreted by the sweat glands on the skin, it evaporates ( evaporation is a cooling mechanism). In addition, our blood vessels dilate to bring blood near the skin’s surface to dissipate body heat. If we go outside on a cold day and our body temperature falls below 98.6 degrees, the hypothalamus of the brain detects this and sends signals to muscles causing us to shiver, which raises the body temperature (increased muscle activity produces heat). In addition, the hypothalamus sends signals to the blood vessels, causing them to constrict, which reduces blood flow near the surface, which conserves body heat.
The functional activities of cells that result in growth, repair, energy release, use of food and secretions are combined under the heading of metabolism. Metabolism consists of two processes that are opposite to each other: anabolism and catabolism. Anabolism is the building up of complex materials from simpler ones such as food and oxygen. Catabolism is the breaking down and changing of complex substances into simpler ones, with a release of energy and carbon dioxide. The sum of all the chemical reactions within a cell is therefore called metabolism.
abdominopelvic [æbˌdɒmɪnəʊˈpelvɪk] of or pertaining to the abdomen and (the cavity of) the pelvis
adenosine [əˈdenəsi:n] (biochemistry) a nucleoside that is a structural component of nucleic acids; it is present in all living cells in a combined form as a constituent of DNA, RNA, ADP, ATP and AMP
anabolism [əˈnæbəˌlɪzəm] synthesis of more complex substances from simpler ones
anatomy [əˈnætəmi] the branch of morphology that deals with the structure of animals
appendix [əˈpendɪks] (pl. appendices or appendixes) a vestigial process that extends from the lower end of the cecum and that resembles a small pouch
bladder [ˈblædə(r)] a distensible membranous sac (usually containing liquid or gas)
bronchus [ˈbrɒŋkəs] (pl. bronchi) either of the two main branches of the trachea
buccal [ˈbʌkəl] of or relating to or toward the cheek
cardiovascular [ˌkɑ:diəʊˈvæskjələ(r)] of or pertaining to or involving the heart and blood vessels
catabolism [kəˈtæbəlɪzəm] breakdown of more complex substances into simpler ones with release of energy
collagen [ˈkɒlədʒən] a fibrous scleroprotein in bone, cartilage, tendon and other connective tissue
cranial [ˈkreɪniəl] of or relating to the cranium which encloses the brain
diaphragm [ˈdaɪəfræm] a muscular partition separating the abdominal and thoracic cavities
digestive [daɪˈdʒestɪv] relating to or having the power to cause or promote digestion
dorsal [ˈdɔ:sl] belonging to or on or near the back or upper surface of an animal or organ or part
endocrine [ˈendəʊkrɑɪn] of or belonging to endocrine glands or their secretions
epithelial [ˌepɪˈθi:lɪəl] of or belonging to the epithelium
esophagus [ɪˈsɒfəgəs] the passage between the pharynx and the stomach
evaporation [ɪˌvæpəˈreɪʃn] the process of becoming a vapor
gallbladder [ˈgɔ:lblædə] a muscular sac that stores and concentrates bile until needed for digestion
homeostasis [ˌhəʊmiəʊˈsteɪsɪs] metabolic equilibrium actively maintained by several complex biological mechanisms that operate via the autonomic nervous system to offset disrupting changes
hypothalamus [ˌhaɪpəˈθæləməs] a basal part of the diencephalon governing autonomic nervous system
integumentary [ɪnˌtegjʊˈmentəri] of or relating to the integument
intestine [ɪnˈtestɪn] the part of the alimentary canal between the stomach and the anus
lacrimal [ˈlækrɪml] of or relating to tears
lymphatic [lɪmˈfætɪk] of or relating to or produced by lymph
malfunction [ˌmælˈfʌŋkʃn] a failure to function normally
mediastinum [ˌmi:dɪəsˈtaɪnəm] (pl. mediastina) the part of the thoracic cavity between the lungs that contains the heart, aorta, esophagus, trachea and thymus
metabolism [məˈtæbəlɪzəm] the organic processes (in a cell or organism) that are necessary for life
mitochondrion [ˌmaɪtəˈkɒndrɪən] (pl. mitochondria) an organelle containing enzymes responsible for producing energy
nasal [ˈneɪzəl] of or in or relating to the nose
optic [ˈɒptɪk] of or relating to or resembling the eye; relating to or using sight
orbital [ˈɔːbɪtl] of or relating to the eye socket
organism [ˈɔːɡənɪzəm] a living thing that has (or can develop) the ability to act or function independently pancreas [ˈpæŋkriəs] a large elongated exocrine gland located behind the stomach which secretes pancreatic juice and insulin
pericardial [perɪˈkɑ:dɪəl] located around the heart or relating to or affecting the pericardium
physiology [ˌfɪziˈɒlədʒi] the branch of the biological sciences dealing with the functioning of organisms
pleural [ˈplʊrə] of or relating to the pleura or the walls of the thorax
rectum [ˈrektəm] (pl. recta or rectums) the terminal section of the alimentary canal, from the sigmoid flexure to the anus
reproductive [ˌri:prəˈdʌktɪv] producing new life or offspring
respiratory [ˈrespərətəri; riˈspaɪə-] pertaining to respiration
skeletal [ˈskelətl] of or relating to or forming or attached to a skeleton
spinal [ˈspaɪnl] of or relating to the spine or spinal cord
sternum [ˈstɜ:nəm] the flat bone that articulates with the clavicles and the first seven pairs of ribs
thoracic [θɔ:ˈræsɪk] of or relating to the chest or thorax
thymus [ˈθaɪməs] a ductless glandular organ at the base of the neck that produces lymphocytes and aids in producing immunity
trachea [treɪkɪə] (pl. tracheae or tracheas) windpipe, the membranous tube with cartilaginous rings that conveys inhaled air from the larynx to the bronchi
triphosphate [traɪˈfɒsfeɪt] a salt or acid that contains three phosphate groups
ureter [jʊəˈri:tə] either of a pair of thick-walled tubes that carry urine from the kidney to the urinary bladder urethra [jʊəˈri:θrə] duct through which urine is discharged in most mammals and which serves as the male genital duct
urinary [ˈjʊərɪnəri] of or relating to the function or production or secretion of urine; of or relating to the urinary system of the body
ventral [ˈventrəl] toward or on or near the belly
vertebra [ˈvɜ:tɪbrə] (pl. vertebrae) one of the bony segments of the spinal column
Directions: Select the letter of the choice that best completes the statement or answers the question.
(1) Which of the following is within the scope of the gross anatomy?
A. The processes of the lungs.B. The structure of the cell.
C. The functions of the liver.D. The size and shape of the kidney.
(2) The study of the function of each body part and how the functions of the various body parts coordinate to form a complete living organism is called____.
A. anatomy B. physiology C. histology D. microbiology
(3) The molecule which is the major source of energy for cellular reactions is called .
A. adenosine triphosphate B. organelle C. mitochondrion D. nucleus
(4) A part of an organism consisting of an aggregate of cells having a similar structure and function is called____.
A. a cell B. a tissue C. an organ D. an organ system
(5) The system that deals with the skin and its appendages is called .
A. the skeletal system B. the reproductive system
C. the integumentary system D. the digestive system
(6) The brain and spinal cord are located in____.
A. the dorsal cavity B. the ventral cavity C. the spinal cavity D. the cranial cavity
(7) The muscular partition separating the abdominal and thoracic cavities is called .
A. the sternum B. the mediastinum C. the diaphragm D. the rectum
(8) The breakdown of more complex substances into simpler ones with release of energy and carbon dioxide is called____.
A. anabolism B. catabolism C. metabolism D. evaporation
(9) The scientific name for the chest cavity is____.
A. the cervical cavity B. the ventral cavity C. the thoracic cavity D. the pelvic cavity
(10)____is the state of steady internal physical and chemical conditions maintained by living systems.
A. Metastasis B. Metabolism C. Hemostasis D. Homeostasis
Directions: Place the following organs in their proper body cavity .
(1) brain _cavity
(2) spinal cord _cavity
(3) esophagus _cavity
(4) thymus gland _cavity
(5) lung _cavity
(6) heart _cavity
(7) liver _cavity
(8) pancreas _cavity
(9) small intestine _cavity
(10) tongue _cavity
(11) urinary bladder _cavity
(12) appendix _cavity
Directions: List the main organs or components of the systems .
Directions: What body systems do you see in the pictures? Write underneath .
