Human Organism Chapter 1 Anatomy PDF

Anatomical anomalies are physical characteristics that differ from the normal pattern. Anatomical anomalies can CHAPTER 1: HUMAN vary...

Anatomical anomalies are physical characteristics that differ from the normal pattern. Anatomical anomalies can CHAPTER 1: HUMAN vary in severity from relatively harmless to life-threatening. ORGANISM Physiology is the scientific investigation of the processes or functions of living things. Anatomy is the scientific discipline that investigates the body’s structures—for example, the shape and size of PHYSIO (nature) bones. LOGY(study of) ANA (apart) The major goals when studying human physiology TOMY (dissect) are to understand and predict the body’s responses to stimuli and to understand how the anatomy means to dissect or cut apart and body maintains conditions within a narrow range separate the parts of the body for study. of values in a constantly changing environment. examines the relationship between the often examines systems rather than regions structure of a body part and its function. because a particular function can involve portions PROVIDES UNDERTANDING ON DISEASES of a system in more than one region Developmental anatomy studies the structural changes Cell physiology examines the processes occurring in cells that occur between conception and adulthood. such as energy production from food. Embryology (em-brēol′ō-jē), a subspecialty of Systemic physiology considers the functions of organ developmental anatomy, considers changes from systems. conception to the end of the eighth week of development. , which focuses on the heart and blood vessels. Cytology (sī-tol′ō-jē; cyto, cell) examines the structural , which focuses on the function features of cells. of the nervous system Histology/Microscopic Anatomy (histol′ō-jē; hist, tissue) Pathology (pa-thol′ō-jē) is the medical science dealing examines tissues, which are composed of cells and the with all aspects of disease, with an emphasis on the cause materials surrounding them. and development of abnormal conditions, as well as the Gross anatomy, the study of structures that can be structural and functional changes resulting from disease. examined without the aid of a microscope, can be Abnormalities approached either systemically or regionally Exercise physiology focuses on the changes in function Systemic Anatomy is a group of structures that have one and structure caused by exercise. or more common functions, such as the cardiovascular, nervous, respiratory, skeletal, or muscular systems. In Homeostasis ability to maintain balance. systemic anatomy, the body is studied system by homeo meaning “similar,” and stasis, meaning “stable.” system. RELATIONSHIP BETWEEN ANATOMY AND PHYSIOLOGY Regional Anatomy study of organization of body areas. Within each region, such as the head, abdomen, or arm, - Inseparable all systems are studied simultaneously. - Lungs, very thin airsacs for gas exchange - Heart, pumping blood Surface anatomy involves looking at the exterior of the - Teeth, for grinding of food body to visualize structures deeper inside the body. Physiological response" refers to the body's automatic Anatomical imaging uses radiographs (x-rays), reactions to stimuli, which can include changes in heart ultrasound, magnetic resonance imaging (MRI), and rate, blood pressure, respiration, hormone levels, and other technologies to create pictures of internal other bodily functions. structures  Interrelationships among the parts of an organism and STRUCTURAL AND FUNCTIONAL how those parts interact to perform specific functions. ORGANIZATION - Living things are highly organized. - All organisms are composed of one or more Chemical level. The structural and functional cells. characteristics of all organisms are determined by their - In turn, cellular function depends on the chemical makeup. precise organization of large molecules. - Disruption of this organized state can result in - The chemical level of organization involves loss of functions, or even death how atoms, such as hydrogen and carbon, interact and combine into molecules 2. Metabolism (mĕ-tab′ō-lizm) is the ability to use - Atoms (colored balls) combine to form energy and to perform vital functions. molecules. - Metabolism refers to all of the chemical Cell level. Cells are the reactions taking place in the cells and internal. Cells contain environment of an organism. smaller structures inside called organelles (or′gă-nelz; - Organisms possess specialized proteins that little organs). Organelles carry out particular functions, break down food molecules. such as. - The organism then uses the nutrients from the food as a source of energy and raw materials - Molecules form organelles, such as the to synthesize new molecules. nucleus and mitochondria, which make up - Energy is also used to rearrange the shape of cells. molecules. Tissue level. A tissue is composed of a group of similar - The shape of a molecule determines its function. Some changes in molecular shape cells and the materials surrounding them. The can allow certain cells to change shape characteristics of the cells and surrounding materials determine the functions of the tissue. The body is 3. Responsiveness is an organism’s ability to sense made up of four basic tissue types: (1) epithelial, (2) changes in its external or internal environment and connective, (3) muscle, and (4) nervous. adjust to those changes. Organ level. An organ is composed of two or more - Responses include actions such as moving tissue types that perform one or more common toward food or water and moving away from functions. danger or poor environmental conditions. Organ system level. An organ system is a group of - Organisms can also make adjustments that maintain their internal environment. organs that together perform a common function or set of functions and are therefore viewed as a unit 4. Growth refers to an increase in the size or number of cells, which produces an overall enlargement of all or - 11 major organ systems: (1) integumentary, (2) part of an organism. skeletal, (3) muscular, (4) nervous, (5) endocrine, (6) cardiovascular, (7) lymphatic, - For example, a muscle enlarged by exercise is (8) respiratory, (9) digestive, (10) urinary, and composed of larger muscle cells than those of (11) reproductive an untrained muscle, and the skin of an adult Organism level. An organism is any living thing has more cells than the skin of an infant. - An increase in the materials surrounding cells considered as a whole—whether composed of one can also contribute to growth. cell, such as a bacterium, or of trillions of cells, such - For instance, bone grows because of an as a human. The human organism is a network of organ increase in cell number and the deposition of systems, all mutually dependent on one another. mineralized materials around the cells. SIX ESSENTIALS CHARACTERISTIC OF LIFE 5. Development includes the changes an organism 1. Organization refers to the specific undergoes through time, beginning with fertilization interrelationships among the parts of an and ending at death. organism and how those parts interact to  5. Endocrine System A major regulatory system that influences metabolism, growth, The greatest developmental changes occur reproduction, and many other functions. before birth, but many changes continue after Consists of glands, such as the pituitary, that birth, and some go on throughout life. secrete hormones. usually involves growth, but it 6. Cardiovascular System Transports nutrients, also involves differentiation and waste products, gases, and hormones morphogenesis. throughout the body; plays a role in the immune involves changes in a cell’s response and the regulation of body structure and function from an immature, temperature. Consists of the heart, blood generalized state to a mature, specialized vessels, and blood. state. 7. Lymphatic System Removes foreign substances For example, following fertilization, immature from the blood and lymph, combats disease, cells differentiate to become specific cell maintains tissue fluid balance, and absorbs types, such as skin, bone, muscle, or nerve dietary fats from the digestive tract. Consists of cells. These differentiated cells form tissues the lymphatic vessels, lymph nodes, and other and organs. lymphatic organs (mōr-fō-jen′ĕ-sis) is the 8. Respiratory System Exchanges oxygen and change in shape of tissues, organs, and the carbon dioxide between the blood and air and entire organism. regulates blood pH. Consists of the lungs and respiratory passages. 6. Reproduction is the formation of new cells or new 9. Digestive System Performs the mechanical and organisms. chemical processes of digestion, absorption of Reproduction of cells allows for growth and nutrients, and elimination of wastes. Consists of development. the mouth, esophagus, stomach, intestines, and All living organisms pass on their genes to accessory organs their offspring. 10. Urinary System Removes waste products from the blood and regulates blood pH, ion balance, ORGAN SYSTEMS and water balance. Consists of the kidneys, urinary bladder, and ducts that carry urine 11. Female Reproductive System Produces oocytes 1. Integumentary System Provides protection, and is the site of fertilization and fetal regulates temperature, prevents water loss, development; produces milk for the newborn; and helps produce vitamin D. Consists of skin, produces hormones that influence sexual hair, nails, and sweat glands. function and behaviors. Consists of the ovaries, 2. Skeletal System Provides protection and uterine tubes, uterus, vagina, mammary glands, support, allows body movements, produces and associated structures blood cells, and stores minerals and adipose. 12. Male Reproductive System Produces and Consists of bones, associated cartilages, transfers sperm cells to the female and ligaments, and joints. produces hormones that influence sexual 3. Muscular System Produces body movements, functions and behaviors. Consists of the testes, maintains posture, and produces body heat. accessory structures, ducts, and penis. Consists of muscles attached to the skeleton by tendons. 4. Nervous System A major regulatory system that detects sensations and controls movements, physiological processes, and intellectual functions. Consists of the brain, spinal cord, nerves, and sensory receptors. TYPES OF CELLS is major energy providing fuel for body cells. 1. **Neurons**: These are specialized cells of the nervous n is essential for building cell structure system that transmit electrical signals throughout the cushion body organs and provide reserve fuel body. They consist of a cell body, dendrites, and an axon. 2. Oxygen 2. **Hepatocytes**: These are the main functional cells of the liver, responsible for a variety of metabolic, chemical reactions that release energy from detoxifying, and synthetic functions, including the foods require oxygen. production of bile. Human cell can only survive a few minutes without oxygen. 3. **Ovum**: The ovum is the female reproductive cell, or egg, in animals. It is a large cell that, when fertilized by 3. Water sperm, can develop into an embryo. 60 to 80 percent of the body weight, depending on 4. **Sarcomeres**: These are the structural units of a the age of individual. muscle fiber, composed of actin and myosin filaments. Single most abundant chemical substance in the Sarcomeres are responsible for the striated appearance of body. skeletal and cardiac muscles and are the basic unit of Fluid base for body secretion and excretion. muscle contraction. Obtain by ingestion or liquids Loose by evaporation from the lungs and skin 5. **Enterocytes**: These are the absorptive cells in the lining of the small intestine. They play a crucial role in the 4. Body temperature digestion and absorption of nutrients. Must be maintain 6. **Thrombocytes**: Also known as platelets, these are If below 37 degree (98.68 F) metabolic reaction small cell fragments in the blood that are essential for became slower. blood clotting and wound healing. Hypothermia: 7. **Sperm**: Sperm are the male reproductive cells, or gametes, that carry half of the genetic material required Definition: Hypothermia occurs when the body loses for the formation of an embryo when they fertilize an heat faster than it can produce it, causing the body's ovum. core temperature to drop below 35°C (95°F). Causes: It typically results from prolonged exposure 8. **Hematite**: This is an iron oxide mineral and is the to cold environments, such as cold-water immersion, main source of iron ore. It is not a biological cell but rather exposure to freezing weather, or inadequate clothing a naturally occurring mineral. in cold conditions. Symptoms: Early symptoms include shivering, 9. **Leukocytes**: These are white blood cells, which are confusion, slurred speech, and fatigue. As part of the immune system and help defend the body hypothermia progresses, shivering may stop, and the against infections and foreign invaders. person can become unconscious, with a risk of heart and respiratory failure. 10. **Osteocytes**: These are mature bone cells that maintain bone tissue. They are derived from osteoblasts Hyperthermia: and are embedded in the mineralized matrix of bone. Definition: Hyperthermia occurs when the body SURVIVAL NEEDS absorbs or produces more heat than it can dissipate, leading to an abnormally high core body temperature. Necessities that an organism needs to sustain This condition can be dangerous and potentially life- life. threatening if not managed promptly. Psychological needs and certain physical needs Causes: It can result from extreme heat exposure, Life is extraordinary fragile vigorous exercise in hot conditions, dehydration, or certain medical conditions and medications that Nutrients, oxygen, water, body temp, and affect the body's ability to regulate temperature. atmospheric pressure. Symptoms: Symptoms can range from heat cramps 1. Nutrients and heat exhaustion to more severe heat stroke, Body takes in through food which includes a high body temperature (above 40°C Contain chemicals used for energy and or 104°F), altered mental state, nausea, rapid cell building. breathing, and even loss of consciousness  Homeostatic mechanisms, such as sweating or shivering, normally maintain body temperature near an ideal normal value, or set Note that these mechanisms are not able to maintain body temperature precisely at the set 5. Atmospheric pressure point. Instead, body temperature increases and decreases slightly around the set point to The force exerted on the surface of the body produce a normal range of values by the weight. Exchange of O and CO2 depends on Negative-feedback mechanisms, which maintain appropriate atmospheric pressure. homeostasis. High altitude, the air is thin negative means “to decrease 1.4 Biomedical Research ” Negative feedback is when any deviation from Studying other organisms has increased our the set point is made smaller or is resisted; knowledge about humans because humans therefore, in a negative-feedback mechanism, share many characteristics with other the response to the original stimulus results in organisms. deviation from the set point, becoming smaller. : (1) a receptor, which monitors the value of a Greek physician, Claudius Galen (ca. 130–201). variable such as body temperature by detecting Galen described a large number of stimuli; anatomical structures supposedly present in (2) a control center, such as part of the brain, humans but observed only in other animals. which determines the set point for the variable For example, he described the liver as having and receives input from the receptor about the five lobes. This is true for rats, but not for variable; and humans, who have four-lobed livers. (3) an effector, such as sweat glands, which can The errors introduced by Galen persisted for adjust the value of the variable when directed by more than 1300 years until a Flemish the control center, usually back toward the set anatomist, point. Andreas Vesalius (1514–1564), Positive Feedback Mechanism who is considered the first modern A positive feedback mechanism amplifies a anatomist, carefully examined human change in a variable, leading to an even greater cadavers and began to correct the textbooks. change in the same direction. This process typically drives a system toward a specific 1.5 Homeostasis outcome, often to completion. is the existence and maintenance of a How It Works: relatively constant environment within the body. A change is detected, and instead of reversing it, To achieve homeostasis, the body must the system enhances or accelerates the change. actively regulate conditions that are This amplification continues until a specific constantly changing event or outcome is achieved, after which the Changes in us environmental conditions, feedback loop is typically interrupted or such as hot or cold outdoor temperatures, are terminated. called because their values are not constant. (1) many disease states result from the failure of negative- For cells to function normally, the volume, feedback mechanisms to maintain homeostasis and temperature, and chemical content of their environment must be maintained within a (2) some positive-feedback mechanisms can be narrow range. detrimental instead of helpful.  - The thorax is the chest cavity where the heart and lungs are located. - The abdomen contains organs such as (1) the ANATOMICAL POSITION liver, (2) the stomach, and (3) the intestines. - The pelvis contains the bladder and The language of anatomy refers to the standardized reproductive organs. terminology used to describe the location, position, and - The upper limb is divided into (1) the arm, (2) the functions of different parts of the human body. This forearm, (3) the wrist, and (4) the hand. language allows healthcare professionals, anatomists, - The arm extends from the shoulder to the elbow, and students to communicate precisely and avoid and the forearm extends from the elbow to the misunderstandings wrist. - The lower limb is divided into (1) the thigh, (2) the LATIN OR GREEK leg (3) the ankle, and (4) the foot. SUFFIX AND PREFIX - The thigh extends from the hip to the knee, and Anatomical position refers to a person standing erect the leg extends from the knee to the ankle with the face directed forward, the upper limbs hanging The abdomen is often subdivided superficially into to the sides, and the palms of the hands facing forward. quadrants by two imaginary lines—one horizontal and A person is when lying face upward and one vertical—that intersect at the navel. when lying face downward The quadrants formed are (1) the right-upper, (2) the left- Directional terms describe parts of the body relative to upper, (3) the right-lower, and (4) the left-lower quadrants each other. Important directional terms. In addition to these quadrants, the abdomen is r means above sometimes subdivided into regions by four imaginary lines: two horizontal and two vertical. means below. These four lines create a “virtual” tic-tac-toe grid on the is used for “in front of,” abdomen, resulting in nine regions: r is used for “behind.” epigastric, is synonymous with ventral (belly) (2) right and left hypochondriac, (3) umbilical, is synonymous with dorsal (back). (4) right and left lumbar, means “close to,” (5) hypogastric, and (6) right and left iliac means “far from.” means “toward the midline,” means “away from the midline.” describes a structure close to the surface of the body, is toward the interior of the body means between two structures Body Parts and Regions Axial head, neck, and trunk. can be further divided into three regions: (1) the thorax, (2) the abdomen, and (3) the pelvis.  2. The Abdominopelvic Cavity is enclosed by abdominal muscles and consists Body Planes and Section a. the more superior abdominal cavity and the more inferior pelvic cavity. it is useful to describe the body as having imaginary b. The organs of the abdominopelvic flat surfaces cavity are housed within the peritoneal (per′i-tō-nē′ăl; to stretch over) cavity. 1. sagittal (saj′i-tăl) plane separates the body or a c. The abdominal cavity contains the structure into right and left halves. The word sagittal majority of the digestive organs, such means “the flight of an arrow” and refers to the way as the stomach, the intestines, and the the body would be split by an arrow passing liver, in addition to the spleen. anteriorly to posteriorly. d. The pelvic cavity continues below the 2. median plane is a sagittal plane that passes pelvis and contains the urinary through the midline of the body, dividing it into equal bladder, urethra, rectum of the large right and left halves. intestine, and reproductive organs 3. Abdominal Cavity bonded by abdominal 3. transverse (horizontal) plane runs parallel to the muscle and contains the stomach, intestines, ground, dividing the body into superior and inferior liver, spleen, pancreas, and kidneys portions. Membranes thin sheets of tissue that covers the body 4. frontal (coronal) (kōr′ŏ-năl, kō-rō′năl; crown) plane divides the body into front (anterior) and back Serous Membranes of the Ventral Body Cavity (posterior) halves. For example, the coronal suture The walls of the body cavities and the surface of internal on the skull is located across the top, where a person organs are in contact with membranes called serous might wear a crown. (sēr′ŭs) membranes. Body Cavities The body contains two types of - double layered. internal cavities: The layer that lines the walls of the cavities is Body contains many cavities called the Houses the organ - The layer covering the internal organs (the Dorsal Body Cavity The dorsal body encloses the viscera) is the. organs of the nervous system, the brain and spinal Thoracic Cavity Membranes cord. The serous membranes are named for the specific (1) the , which houses the cavity and organs they are in contact with. They include: brain, (2) the , which houses the 1. Pericardial Cavity The pericardial cavity (peri = spinal cord. around; cardi = heart), containing the heart, is housed in the mediastinum. The parietal serous Both the brain and spinal cord are covered by membrane is called the , membranes called and the visceral serous membrane is called the Ventral Body Cavity The ventral body cavity houses. The space between the the vast majority of our internal organs, collectively two pericardial membranes is called the referred to as the viscera (vis′er-ah; internal organs) and is filled with pericardial fluid. (1) is more superior to the 2. Pleural Cavities Each of the two pleural cavities abdominopelvic cavity and houses primarily (pleuron = side of body, rib) houses a lung. The the heart and lungs, among other organs. parietal serous membrane lining the pleural - Surrounded by the ribcage, cavities is called the , while the separated from the abdominal serous membrane covering the lungs is called cavity by the muscular diaphragm. the The space between the two - The mediastinum is a space in the pleural membranes is called the chest cavity. and is filled with pleural fluid. 3. 3. Peritoneal Cavity The peritoneal cavity (peri = around; -tonos = stretched; stretched around) houses many internal organs, such as the liver, the digestive organs, and the reproductive organs. The parietal serous membrane in the peritoneal cavity is called the The visceral serous membrane is called the. The space between the two serous membranes is the specific location of the peritoneal cavity and is filled with. In addition to covering organs, a double- folded sheet of visceral peritoneum attaches the digestive organs at certain points to the posterior abdominopelvic cavity wall. These regions of double-folded visceral peritoneum are called retroperitoneal (re′trō-per′i-tō nē′ăl; behind the peritoneum) location and include the kidneys, ureters, adrenal glands, a large portion of the pancreas, parts of the large intestine, and the urinary bladder.  The mass number of an element is the number of protons plus the number of neutrons in each atom. CHAPTER 2; The Chemical Basis of Isotopes and Atomic Mass Life Isotopes (I‾′sō-tōpz) are two or more forms of the MATTER - which is anything that occupies space and has same element that have the same number of mass. protons and electrons but a different number of MASS - is the amount of matter in an object. neutrons. Thus, isotopes have the same atomic number but different mass numbers. WEIGHT - is the gravitational force acting on an object of a given mass. Electrons and Chemical Bonding KILOGRAM – is the international unit for mass The key to the first level, the chemical level, is the which is the mass of a platinum-iridium cylinder. concept of how atoms interact to form molecules by sharing and transferring their outermost electrons Elements and Atoms to form chemical bonds. ELEMENT is the simplest type of matter, having unique The chemical behavior of an atom is dependent on chemical properties. its electrons. About 96% of the body’s weight results from the Energy levels are often depicted as concentric rings, elements oxygen, carbon, hydrogen, and called electron shells, around the nucleus. nitrogen. The outermost shell is called the valence shell. ATOMS (atomos, indivisible) is the smallest particle of an Electronegativity is the ability of an atom’s nucleus element that has the chemical characteristics of that element. to attract electrons. When the electronegativities of two atoms An element is composed of atoms of only one forming a chemical bond are similar, the kind. atoms tend to share, rather than transfer, Atomic Structure the electrons. Atoms are composed of subatomic particles, some of Ionic bonds are a type of chemical bond that forms which have an electrical charge. between two atoms when one atom donates an electron to another, resulting in the creation of two has no electrical charge, a has one oppositely charged ions. positive charge, and an has one negative charge. These oppositely charged ions are then Most of the volume of atoms is occupied by attracted to each other due to electrostatic electrons forces, which hold them together. The number of protons and the number of electrons in Positively charged ions are called cations (kat′ī-onz), each atom are equal, and the individual charges cancel and negatively charged ions are called anions (an′ī- each other. Therefore, each atom is electrically neutral. onz) Protons and neutrons form the nucleus at the center of an ionic (ī-on′ik) bond forms when electrons are atom, and electrons move around the nucleus transferred between atoms, creating oppositely Atomic Number and Mass Number charged ions. The atomic number of an element is equal to the number covalent bond forms when atoms share one or more of protons in each atom and, because the number of pairs of electrons. electrons is equal to the number of protons, the atomic sharing of one pair of electrons by two atoms results number is also the number of electrons. in a. results when two atoms share 4 electrons, 2 from each atom.  Dissociation Definition: Dissociation is the process in which a compound breaks down into smaller components, such as ions, when dissolved in a solvent. For ionic compounds, dissociation When electrons are shared equally between atoms, as involves the separation of the compound into in a hydrogen molecule, the bonds are called its constituent ions. Cations and anions that dissociate in water are where the two atoms involved in a covalent bond have sometimes called electrolytes (eˉ-lek′troˉ-lītz) because different electronegativities, will they have the capacity to conduct an electric current, form. which is the flow of charged particles. Molecules and Compounds Molecules that do not dissociate form solutions that molecule is composed of two or more atoms do not conduct electricity and are called chemically combined to form a structure that nonelectrolytes. behaves as an independent unit 2.2 Chemical Reactions and compound is a substance resulting from the chemical Energy combination of two or more different types of atoms. A chemical reaction occurs when atoms, ions, Intermolecular Forces molecules, or compounds interact either to form or to Intermolecular forces are the weak electrostatic break chemical bonds. attractions that exist between oppositely charged parts The substances that enter into a chemical reaction are of molecules, or between ions and molecules. called There is no exchange of electrons in the substances that result from the chemical reaction intermolecular forces. are called This differs from other chemical bonds. Intermolecular forces are much weaker than Synthesis Reactions the forces producing chemical bonding. Intermolecular forces include hydrogen A synthesis reaction is when two or more reactants bonds and the properties of solubility and chemically combine to form a new and larger product. dissociation. Build Hydrogen Bonds If the positively charged hydrogen of Anabolism one molecule is attracted to the negatively charged Synthesis reactions in which water is a product are oxygen, nitrogen, or fluorine of another molecule. called (water out) reactions Intramolecular Bonds Another example of a synthesis reaction in the body is Definition: Intramolecular bonds are the the formation of adenosine triphosphate bonds that hold atoms together within a ATP, which is composed of adenosine and three molecule. These bonds are responsible for the phosphate groups, is synthesized from adenosine molecule's internal structure. diphosphate (ADP), which has two phosphate groups, Solubility and Dissociation and an inorganic phosphate (H2PO4 ) that is often symbolized as Solubility is the ability of one substance to dissolve in another—for example, sugar dissolving in water. Pi: A-P-P + Pi → A-P-P-P (ADP) (Inorganic (ATP) phosphate the maximum amount of a substance (solute) that can dissolve in a solvent (such as water) A decomposition reaction is the reverse of a synthesis at a specific temperature and pressure to form reaction—a larger reactant is chemically broken down a homogeneous solution. into two or more smaller products. catabolism  Speed of Chemical Reactions A chemical reaction occurs only when molecules with sufficient kinetic energy collide with each other. Like charge repel. All of the anabolic and catabolic reactions in the Unlike charge attracts body are collectively defined as. Activation energy is the minimum amount of energy Reversible Reactions that the reactants must have to start a chemical reaction. A reversible reaction is when the reaction can run in the opposite direction, so that the products are Catalysts (kat′a˘-listz) are substances that converted back to the original reactants. increase the rate of chemical reactions without being permanently changed or When the rate of product formation is equal to the rate depleted themselves. of the reverse reaction, the reaction system is said to Enzymes (en′zīmz), which are discussed in be at equilibrium. greater detail later in the chapter, are proteins Oxidation-Reduction Reactions that act as catalysts. o Enzymes increase the rate of The loss of an electron by an atom is called chemical reactions by lowering the , and the activation energy necessary for the gain of an electron is called. reaction to begin. one atom partially or completely loses an electron o An enzyme allows the rate of a and another atom gains that electron, these reactions chemical reaction to take place more are called oxidation-reduction reaction. than a million times faster than it would without the enzyme. Energy Temperature can also affect the speed of Energy is the capacity to do work—that is, to move chemical reactions. matter. o As temperature increases, reactants have more kinetic energy, move at is stored energy that could faster speeds, and collide with one do work but is not doing so another more frequently and with is the form of greater force, thereby increasing the energy that is actually doing work and moving likelihood of a chemical reaction. matter results from the position or movement of objects. Chemical Energy Chemical energy is a form of potential energy stored within the chemical bonds of a substance. Heat Energy Heat energy is a form of energy that flows from a hotter object to a cooler object. Temperature is a measure of how hot or cold a substance is relative to another substance. All other forms of energy can be converted into heat energy.  Water protects the body by two ways: as a lubricant and as a cushion. 2.3 Inorganic Chemistry (1) By acting as a lubricant, water reduces Inorganic chemistry generally deals with substances damage from friction. For example, tears that do not contain carbon, although a more rigorous protect the surface of the eye from rubbing of definition is the lack of carbon-hydrogen bonds. the eyelids. Organic chemistry is the study of carbon-containing (2) By forming a fluid cushion around organs, substances, with a few exceptions. water helps protect the organs from trauma. For exam ple, carbon monoxide (CO), carbon dioxide (CO2), and bicarbon ate ions (HCO3 Many of the chemical reactions necessary for life do not −) are several important inorganic substances take place unless the reacting molecules are dissolved that contain carbon but lack C—H bonds. in water. Water Water also directly participates in many Water has remarkable properties due to its polar chemical reactions. nature. A molecule of water is formed when an atom of As previously mentioned, a dehydration oxygen forms polar covalent bonds with two atoms of reaction is a synthesis reaction that produces hydrogen. water, and a hydrolysis reaction is a decomposition reaction that requires water. Molecules that are attracted to water are called (hi-dro-fil’ ik; water-loving). molecules that lack this attraction are called A mixture is a combination of two or more substances (hī-drō-fōb′ik; water-fearing). physically blended together, but not chemically Cohesion is the attraction of water to another water combined. molecule. A solution is any mixture in which the substances are Adhesion is the attraction of water to other molecules. uniformly distributed. Solutions can be liquid, gas, or solid. Water accounts for approximately 50% of the weight of a young adult female and 60% of a The solute (sol′uˉ t) dissolves in the solvent. young adult male. A suspension is a mixture containing materials that Females have a lower percentage of water separate from each other unless they are continually, than males because they typically have more physically blended together. body fat, which is relatively free of water. A colloid (kol′oyd) is a mixture in which a dispersed substance or particle is unevenly distributed throughout the mixture. Water helps stabilize body temperature in two Unlike a suspension, the dispersed particles ways: absorption of heat and evaporation. are small enough that they do not settle out. (1) Water can absorb large amounts of heat yet Solution Concentrations remain at a stable temperature. As a result of Concentration in chemistry refers to the amount of a this property, blood, which is mostly water, substance (solute) present in a given quantity of a can transfer heat from deep in the body to the solution or mixture. It indicates how much solute is surface, where the heat is released. dissolved in a solvent, usually expressed in terms of (2) When water evaporates, it changes from a mass, volume, or moles. liquid to a gas and because heat is required for that process, the evaporation of water from the surface of the body rids the body of excess