Anatomy Part 1 PDF

AN OVERVIEW OF ANATOMY AND PHYSIOLOGY OBJECTIVES: 1. Define Anatomy and Physiology and how they are related. 2. Identify and classify the different organ system of the body.  ANATOMY AND PHYSIOLOGY  Anatomy (ah-nat′o-me) is the study of the structure and shape of t...

AN OVERVIEW OF ANATOMY AND PHYSIOLOGY OBJECTIVES: 1. Define Anatomy and Physiology and how they are related. 2. Identify and classify the different organ system of the body.  ANATOMY AND PHYSIOLOGY  Anatomy (ah-nat′o-me) is the study of the structure and shape of the body and its parts and their relationships to one another. Indeed, the term anatomy, derived from the Greek words meaning to cut (tomy) apart (ana), is related most closely to gross anatomical studies because in such studies, preserved animals or their organs are dissected (cut up) to be examined.  Two Major Types of Anatomy 1. Gross Anatomy  Is the study of large body structures such as the heart or bones, easily observable structures.  Is the study of anatomical structures that can be seen by the naked eye, such as the external and internal bodily organs. Gross anatomy can be further subdivided into three different fields:  Surface anatomy or superficial anatomy - is the study of external anatomical features without dissection.  Regional anatomy - focuses on specific external and internal regions of the body (such as the head or chest) and how different systems work together in that region.  Systemic anatomy - focuses on the anatomy of different organ systems, such as the respiratory or nervous system.  Two Major Types of Anatomy 2. Microscopic anatomy - is the study of body structures that are too small to be seen with the naked eye. The cells and tissues of the body can only be seen through a microscope. Within microscopic anatomy, two topics of study are of great importance:  Cytology - the study of the structure and function of cells.  Histology - the study of the organization and details of biological tissues.  Physiology Physiology (fiz″e-ol′o-je) is the study of how the body and its parts work or function (physio = nature; ology = the study of).  Relationship between Anatomy and Physiology Anatomy and physiology are always inseparable. The parts of your body form a well-organized unit, and each of those parts has a job to do to make the body operate as a whole. Structure determines what functions can take place. For example, the lungs are not muscular chambers like the heart and so cannot pump blood through the body, but because the walls of their air sacs are very thin, they can exchange gases and provide oxygen to the body.  Levels of Structural Organization from Atoms to Organisms  The human body exhibits many levels of structural complexity.  The simplest level of the structural ladder is the chemical level. At this level, atoms, tiny building blocks of matter, combine to form molecules such as water, sugar, and proteins, like those that makeup our muscles.  Molecules, in turn, associate in specific ways to form microscopic cells, the smallest units of all living things (cellular level). All cells have some common structures and functions, but individual cells vary widely in size, shape, and their particular roles in the body.  The simplest living creatures are composed of single cells, but in complex organisms such as trees or human beings, the structural ladder continues on to the tissue level.  Tissues consist of groups of similar cells that have a common function. There are four basic tissue types, and each plays a definite but different role in the body.  Levels of Structural Organization from Atoms to Organisms  An organ is a structure composed of two or more tissue types that performs a specific function for the body.  At the organ level of organization, extremely complex functions become possible. For example, the small intestine, which digests and absorbs food, is composed of all four tissue types.  An organ system level is a group of organs that work together to accomplish a common purpose. For example, the heart and blood vessels of the cardiovascular system circulate blood continuously to carry nutrients and oxygen to all body cells.  In all, 11 organ systems make up the living human being, or the organism, which represents the highest level of structural organization, the organismal level.  The organismal level is the sum total of all structural levels working together to keep us alive. Introduction to the Human Body Human beings are arguably the most complex organisms on this planet. Imagine billions of microscopic parts, each with its own identity, working together in an organized manner for the benefit of the total being.  The human body is a single structure but it is made up of billions of smaller structures of four major kinds:  Cells Cells have long been recognized as the simplest units of living matter that can maintain life and reproduce themselves. The human body, which is made up of numerous cells, begins as a single, newly fertilized cell.  Tissues Tissues are somewhat more complex units than cells. By definition, a tissue is an organization of a great many similar cells with varying amounts and kinds of nonliving, intercellular substance between them. The human body is a single structure but it is made up of billions of smaller structures of four major kinds:  Organs Organs are more complex units than tissues. An organ is an organization of several different kinds of tissues so arranged that together they can perform a special function. For example, the stomach is an organization of muscle, connective, epithelial, and nervous tissues. Muscle and connective tissues form its wall, epithelial and connective tissues form its lining, and nervous tissue extends throughout both its wall and its lining.  Systems Systems are the most complex of the component units of the human body. A system is an organization of varying numbers and kinds of organs so arranged that together they can perform complex functions for the  Eleven major systems compose the human body: 1. Integumentary System  The integumentary (in-teg″u-men′tar-e) system is the external covering of the body, or the skin, including the hair and fingernails. It waterproofs the body and cushions and protects the deeper tissues from injury. With the help of sunlight, it produces vitamin D. It also excretes salts in perspiration and helps regulate body temperature. Sensory receptors located in the skin alert us to what is happening at the body surface. 2. Skeletal System  The skeletal system consists of bones, cartilages, and joints. It supports the body and provides a framework that the skeletal muscles use to cause movement. It also has protective functions (for example, the skull encloses and protects the brain), and the cavities of the skeleton are the sites where blood cells are formed. The hard substance of bones acts as a storehouse for minerals.  Eleven major systems compose the human 3. Muscular System body:  The muscles of the body have only one function— to contract, or shorten. When this happens, movement occurs. The mobility of the body as a whole reflects the activity of skeletal muscles, the large, fleshy muscles attached to bones. When these contract, you are able to stand erect, walk, jump, grasp, throw a ball, or smile. The skeletal muscles form the muscular system. These muscles are distinct from the muscles of the heart and of other hollow organs, which move fluids (such as blood or urine) or other substances (such as food) along definite pathways within the body. 4. Nervous System  The nervous system is the body’s fast-acting control system. It consists of the brain, spinal cord, nerves, and sensory receptors. The body must be able to respond to stimuli coming from outside the body (such as light, sound, or changes in temperature) and from inside the body (such as decreases in oxygen or stretching of tissue). The sensory receptors detect changes in temperature, pressure, or light, and send messages (via electrical signals called nerve impulses) to the central nervous system (brain and spinal cord) so that it is constantly informed about what is going on. The central nervous system then assesses this information and responds by activating the appropriate body effectors (muscles or glands, which are organs that produce secretions). Eleven major systems compose the human body: 5. Endocrine System  Like the nervous system, the endocrine (en′do-krin) system controls body activities, but it acts much more slowly. Endocrine glands produce chemical molecules called hormones and release them into the blood to travel to relatively distant target organs. The endocrine glands include the pituitary, thyroid, parathyroids, adrenals, thymus, pancreas, pineal, ovaries (in the female), and testes (in the male) (Figure 1.2e). The endocrine glands are not connected anatomically in the same way that the parts of other organ systems are. What they have in common is that they all secrete hormones, which regulate other structures. The body functions controlled by hormones are many and varied, involving every cell in the body. Growth, reproduction, and the use of nutrients by cells are all controlled (at least in part) by hormones. 6. Cardiovascular System  The primary organs of the cardiovascular system are the heart and blood vessels (Figure 1.2f). Using blood as a carrier, the cardiovascular system delivers oxygen, nutrients, hormones, and other substances to, and picks up wastes such as carbon dioxide from, cells near sites of exchange. White blood cells and chemicals in the blood help to protect the body from such foreign invaders as bacteria, viruses, and tumor cells. The heart propels blood out of its chambers into blood vessels to be transported to all body tissues. Eleven major systems compose the human body: 7. Lymphatic System  The role of the lymphatic system complements that of the cardiovascular system. Its organs include lymphatic vessels, lymph nodes, and other lymphoid organs such as the spleen and tonsils (Figure 1.2g). When fluid is leaked into tissues from the blood, lymphatic vessels return it to the bloodstream so that there is enough blood to continuously circulate through the body. The lymph nodes and other lymphoid organs help to cleanse the blood and house white blood cells involved in immunity. 8. Respiratory System  The job of the respiratory system is to keep the body supplied with oxygen and to remove carbon dioxide. The respiratory system consists of the nasal passages, pharynx, larynx, trachea, bronchi, and lungs (Figure 1.2h). Within the lungs are tiny air sacs. Gases are exchanged with the blood through the thin walls of these air sacs.  Eleven major systems compose the human body: 9. Digestive System  The digestive system is basically a tube running through the body from mouth to anus. The organs of the digestive system include the oral cavity (mouth), esophagus, stomach, small and large intestines, and rectum plus a number of accessory organs (liver, salivary glands, pancreas, and others) (Figure 1.2i). Their role is to break down food and deliver the resulting nutrients to the blood for dispersal to body cells. The breakdown activities that begin in the mouth are completed in the small intestine. From that point on, the major function of the digestive system is to reabsorb water. The undigested food that remains in the tract leaves the body through the anus as feces. The liver is considered a digestive organ because the bile it produces helps to break down fats. The pancreas, which delivers digestive enzymes to the small intestine, has both endocrine and digestive functions. 10. Urinary System  A normal part of healthy body function is the production of waste by-products, which must be disposed of. One type of waste contains nitrogen (examples are urea and uric acid), which results when the body cells break down proteins and nucleic acids, which are genetic information molecules. The urinary system removes the nitrogen-containing wastes from the blood and composed of the kidneys, ureters, bladder, and urethra (Figure 1.2j). Other important functions of this system include maintaining the body’s water and salt (electrolyte) balance, regulating the acid-base balance of the blood, and helping to regulate normal blood pressure.  Eleven major systems compose the human body: 11. Reproductive System  The role of the reproductive system is to produce offspring. The male testes produce sperm. Other male reproductive system structures are the scrotum, penis, accessory glands, and the duct system, which carries sperm to the outside of the body (Figure 1.2k). The female ovaries produce eggs, or ova; the female duct system consists of the uterine tubes, uterus, and vagina (Figure 1.2l). The uterus provides the site for the development of the fetus (immature infant) once fertilization has occurred.