basic knowledge of anatomy. Flashcards
(16 cards)
Chemical Level
Atoms combine to form molecules (e.g., water, proteins, DNA).
Cellular Level
Molecules come together to form cells, which are the basic units of life.
Tissue Level
Similar cells group together to form tissues.
Organ Level
Different types of tissues combine to form an organ (not just similar tissues).
Example: The stomach contains muscle tissue, epithelial tissue, and connective tissue.
Organ System Level
Organs work together to form an organ system (like the digestive or cardiovascular system).
Organismal Level
All the organ systems together make up the entire living organism (the human body).
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 (Figure 1.2a). 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.
Skeletal System
The skeletal system consists of bones, cartilages, and joints (Figure 1.2b). 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.
Muscular System
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 (Figure 1.2c). 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 specific pathways within the body.
Nervous System
The nervous system is the body’s fast-acting control system. It consists of the brain, spinal cord, nerves, and sensory receptors (Figure 1.2d). 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).
Endocrine System
Like the nervous system, the endocrine (en′dokrin) 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 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.
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.
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, called alveoli. Gases are exchanged with the blood through the thin walls of these alveoli.
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 absorb nutrients and 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.
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 flushes them from the body in urine. This system, often called the excretory system, is 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.
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.
