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Anatomy and Physiology. Introduction to Human Anatomy and Physiology. Introduction. The study of the human body probably began with our earliest ancestors. Early healers relied heavily on superstitions and magic.
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Anatomy and Physiology Introduction to Human Anatomy and Physiology
Introduction • The study of the human body probably began with our earliest ancestors. • Early healers relied heavily on superstitions and magic. • Over time, people began to believe that humans could understand forces that caused natural events; this developed into modern science.
Anatomy and Physiology • Anatomy is the branch of science that deals with the structure (morphology) of body parts—forms and organization. • Physiology concerns the functions of body parts—what they are and what they do. • Body parts form a well-organized unit—the human organism. • A particular body part’s function depends on its structure.
Levels of Organization in Living Things • Cellorganellestissuesorgans organ systemsorganism • Organelles—structures that carry on specific activities; composed of aggregates of large molecules • Tissues—cells organized into layers or masses that have common functions
Levels of Organization continued: • Organs—tissues form complex structures with specialized functions • Organ systems—groups of organs that function closely together • Organism—the entire group of organs making up an individual
Levels of Organization • Scientists recognize that all materials are composed of chemicals. • Hierarchy of all substances begins with atoms, which join to form molecules, which then combine into macromolecules. • Within the human organism, the basic unit of structure and function is the cell.
Summary of Organization • Body parts can be thought of as having different levels of organization, such as the atomic level, molecular level, or cellular level. • As you move from 1 level to the next, complexity increases (cells are more complicated than atoms).
Movement Responsiveness Growth Reproduction Respiration Digestion Absorption Circulation Assimilation Excretion Characteristics of Life
Characteristics of Life Defined • Movement—a self-initiated change in an organism’s position or to motion of internal parts. • Responsiveness—an organism’s ability to sense changes taking place inside or outside its body and to react to these changes • Growth—an increase in body size
Characteristics of Life Defined • Reproduction—process of making a new individual • Respiration—process of obtaining oxygen, using oxygen to release energy from food, and removing the resulting gaseous wastes • Digestion—chemically and mechanically breaks down food into simpler forms for cellular use
Characteristics of Life Defined • Absorption—the passage of substances through certain membranes • Circulation—movement of substances within the body fluids • Assimilation—the changing of absorbed substances into chemically different forms • Excretion—removal of wastes produced as a result of body activities
Metabolism • Each of the characteristics of life depends upon physical and chemical changes that occur within body parts. • Taken together, these changes are called metabolism.
Maintenance of Life • The structures and function of almost all body parts help maintain the life of the organism. • The only exceptions are an organism’s reproductive structures, which ensure that its species will continue into the future.
Requirements to Maintain Life • Water is the most abundant chemical in the body. It is required for many metabolic processes, transports substances with the body, and is important in regulating temperature. • Foods are substances that provide the body with the necessary nutrients—used as energy sources, building materials, and to help regulate vital chemical reactions.
Requirements continued: • Oxygen is used to release energy from food which drives metabolic processes. • Heat energy is a product of metabolic reactions. Generally, the more heat, the more rapidly chemical reactions take place (temperature is a measure of heat). • Pressure is an application of force to something and is important in breathing. Hydrostatic pressure produces blood pressure.
Survival • Although organisms require water, food, oxygen, heat, and pressure, theses factors alone are not enough to ensure survival. • The quantities and the qualities of the factors are also important. • The amount of water entering and leaving an organism must be regulated. • Survival depends on the correct nutrients in adequate amounts in an organism’s food.
Homeostasis • As factors in an organism’s external environment change, the conditions within the organism (internal environment) must remain relatively stable in order for the organism to survive. • The maintenance of a stable internal environment is called homeostasis.
The Set Point • Like a thermostat, the body is adjusted to an operating level called a set point. • Body temperature in humans is regulated by a homeostatic mechanism. • A temperature-sensitive region in the brain will trigger homeostatic mechanisms to maintain a set point of around 37o C.
Homeostasis in a Cold Environment • If the body temperature begins to drop, the brain senses the change and triggers heat-generating and heat-conserving activities. • Small groups of muscles are stimulated to contract involuntarily (shivering) which produces heat to help warm the body. • Also, blood vessels in the skin are signaled to constrict so that less warm blood flows through them; this retains heat in deeper tissues.
Homeostasis in a Warm Environment • When a body becomes too hot, the brain’s temperature control center triggers a series of changes to promote loss of body heat. • Sweat glands secrete perspiration; as water evaporates from the surface, heat is carried away and the skin is cooled. • Blood vessels in the skin dilate, allowing blood carrying heat to reach the surface where it is lost to the outside.
Other Homeostatic Mechanisms • Pressure sensitive areas (receptors) in the walls of blood vessels (arteries) sense changes in blood pressure and signal a pressure control center of the brain. • If the pressure is above the set point, the brain signals the heart, causing its chambers to contract more slowly and with less force. Since less blood enters the vessels, pressure decreases. • If pressure is below the set point, the brain signals the heart to contract more rapidly and with greater force in order to raise pressure.
Feedback Mechanism • Homeostasis is maintained by a self-regulating control mechanism that receives signals or feedback about changes away from the normal set point. • Since the changes away from the normal state stimulate responses in the opposite direction, the responses are called negative and the control mechanism is called a negative feedback process.
Normal Range • Homeostatic mechanisms maintain a relatively constant internal environment, but individuals are different. • Each individual has a normal value so the concept of a normal range for the population is clinically important.
The human organism can be divided into: axial portion--includes the head, neck, and trunk appendicular portion-- includes the upper and lower limbs. Body Portions
The axial portion has 2 major cavities: a dorsal cavity and a larger ventral cavity. The organs within a cavity are called visceral organs or viscera. Parts of the Axial Portion
Dorsal Cavity • There are 2 parts to the dorsal cavity: • the cranial cavity, within the skull, houses the brain • The vertebral canal, which contains the spinal cord within sections of the backbone (vertebrae)
Ventral Cavity • The ventral cavity consists of a thoracic cavity and an abdominopelvic cavity. • The thoracic cavity is separated from the lower abdominopelvic cavity by a broad, thin muscle called the diaphragm.
Thoracic Cavity • The thoracic cavity wall is composed of skin, skeletal (voluntary) muscles, and various bones. • A region called the mediastinum separates the thoracic cavity into 2 compartments, which contain the right and left lungs.
The remaining thoracic viscera—heart, esophagus, trachea, and thymus gland—are located with the mediastinum. The Mediastinum
The abdominopelvic cavity includes an upper abdominal portion and a lower pelvic portion. It extends from the diaphragm to the floor of the pelvis. The viscera within the abdominal cavity include the stomach, liver, spleen, gallbladder, kidneys, and most of the small and large intestines. Abdominopelvic Cavity
The Pelvic Cavity • The pelvic cavity is the portion of the abdominopelvic cavity enclosed by the hip bones and contains the terminal portion of the large intestine, the urinary bladder, and the internal reproductive organs.
Cavities Within the Head • Oral cavity—contains the teeth and tongue. • Nasal cavity—located within the nose; divided into right and left portions by a nasal septum; connected to air-filled sinuses • Orbital cavities—contain eyes and associated skeletal muscles and nerves. • Middle ear cavities—contain the middle ear bones
Thoracic and Abdominopelvic Membranes • Parietal pleura—membrane lining the walls of the right and left thoracic compartments • Visceral pleura—membrane covering the lungs. • (parietal refers to membrane attached to the cavity wall; visceral refers to membranes covering an organ)
Membranes Continued • Parietal and visceral pleural membranes are separated by a thin film of watery fluid (serous fluid) that they secrete. The potential space between them is called the pleural cavity.
The Heart • The heart is surrounded by pericardial membranes. • A thin visceral pericardium covers the heart’s surface and is separated from a thicker parietal pericardium by a small amount of fluid. • The pericardial cavity is the potential space between these membranes.
Parietal Peritoneum • In the abdominopelvic cavity, the lining membranes are called peritoneal membranes. • A parietal peritoneum lines the wall, and a visceral peritoneum covers each organ in the abdominal cavity. • The peritoneal cavity is the potential space between these membranes.
Integumentary system Skeletal system Nervous system Endocrine system Cardiovascular system 6. Lymphatic system Digestive system Respiratory system Urinary system Reproductive system Organ Systems
Body Covering • Organs of the integumentary system include the skin and various accessory organs, such as the hair, nails, sweat glands, and sebaceous glands. • These parts protect underlying tissues, help regulate body temperature, house a variety of sensory receptors, and synthesize certain products.
Support • The organs of the skeletal and muscular systems support and move body parts. • The skeletal system consists of bones, and ligaments and cartilages which bind bones together. • The skeleton provides framework and protective shields for soft tissue, is attachment for muscles, and stores inorganic salts.
Muscles provide forces that cause body movements by contracting and pulling their ends closer together. Muscles also maintain posture and are the main source of body heat. Movement
Integration and Coordination • For the body to act as a unit, its parts must be integrated and coordinated. • The nervous system and endocrine systems control and adjust various organ functions, which maintains homeostasis.
Nervous System • The nervous system consists of the brain, spinal cord, nerves, and sense organs. • Nerve cells within these organs use electrochemical signals called nerve impulses to communicate with one another and with muscles and glands.
Endocrine System • The endocrine system includes all the glands that secrete chemical messengers called hormones. • The hormones move away from the glands in body fluids, such as blood. • Usually, a particular hormone affects only a particular group of cells, or target tissue. • The effect of a hormone is to alter the metabolism of the target tissue. • Organs of the endocrine system include the pituitary, thyroid, parathyroid, and adrenal glands, as well as the pancrease, ovaries, testes, pineal gland, and thymus gland.
Cardiovascular System • The cardiovascular system includes the heart, arteries, veins, capillaries, and blood. • The heart is a muscular pump that helps force blood through the blood vessels. • Blood transports gases, nutrients, hormones, and wastes. It carries O2 from the lungs to all parts of the body.
Lymphatic System • The lymphatic system is sometimes considered part of the cardiovascular system. • It is composed of the lymphatic vessels, lymph fluid, lymph nodes, thymus gland, and spleen. • This system transports some of the tissue fluid back to the bloodstream and carries certain fatty substances away from the digestive organs. • Cells of the lymphatic system are called lymphocytes and they defend the body against infection.
Digestive System • The organs of the digestive system receive foods from the outside. Then they break down food molecules into simpler forms that can pass through cell membranes and be absorbed. • The digestive system includes the mouth, tongue, teeth, salivary glands, pharynx, esophagus, stomach, liver, gallbladder, pancreas, small intestine, and large intestine.
Respiratory System • The organs of the respiratory system take air in and out and exchange gases between the blood and the air. • Oxygen passes from air within the lungs into the blood, and carbon dioxide leaves the blood and enters the lungs. • The nasal cavity, pharynx, larynx, trachea, bronchi, and lungs are parts of this system.
Urinary System • The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. • Kidneys remove wastes from blood and help maintain the body’s water and electrolyte balance. The product of these activities is urine.
The male reproductive system includes the scrotum, testes, epididymides, vasa deferentia, seminal vesicles, prostate gland, bulbourethral glands, penis, and urethra. These parts produce and transfer sperm. The female reproductive system consists of the ovaries, uterine tubes, uterus, vagina, clitoris, and vulva. These organs produce and maintain eggs and support the development of embryos and fetuses. Reproductive System Reproduction is the process of producing offspring (progeny).