Chapter 2 Basic Chemistry. Introduction . Our bodies are made of different chemicals. To understand the body, you need to understand some general chemical principles. Matter, Elements, and Atoms. Matter Matter is anything that occupies space and has weight.
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Introduction • Our bodies are made of different chemicals. To understand the body, you need to understand some general chemical principles.
Matter, Elements, and Atoms • Matter • Matter is anything that occupies space and has weight. • Matter exists in three states: solid, liquid, and gas. • Matter can undergo physical and chemical changes.
Matter, Elements, and Atoms - cont’d • Elements • An element is a fundamental substance that cannot be broken down into a simpler form by ordinary chemical means. • Four elements (carbon, hydrogen, oxygen, and nitrogen) make up 96% of the body weight.
Matter, Elements, and Atoms - cont’d • Atoms • An atom is the basic unit of matter. • An atom is composed of three subatomic particles: neutrons, protons, and electrons. • The atomic number: the number of protons. • The atomic weight: the number of neutrons and protons. • An isotope is an atom with the same atomic number but a different atomic weight. A radioisotope is an unstable isotope.
Chemical Bonds • Electron Shells and Bonding • Each electron shell holds a specific number of electrons. • Ionic bonds are formed as electrons are transferred to stabilize the shells of the atoms. • Covalent bonds are formed as the electrons of the outer shells are shared by the interacting atoms. • Hydrogen bonds are intermolecular bonds.
Chemical Bonds - cont’d • Ion Formation • An ion is an atom that carries an electrical charge. A cation is a positively charged ion. An anion is a negatively charged ion. • An electrolyte is a substance that forms ions when dissolved in water.
Chemical Bonds - cont’d • Molecules and Compounds • A molecule is a substance formed by two or more atoms (O2, H2O). • A compound is a substance that forms when two or more different atoms bond (H2O). • Important molecules and compounds include water, oxygen, and carbon dioxide.
Chemical Bonds - cont’d • Acids and Bases • An acid is an electrolyte that dissociates into a hydrogen ion (H+) and an anion. • A base is a substance that combines with H+ and eliminates H+; a base neutralizes an acid by producing a salt and water. • The pH scale measures acidity and alkalinity. A pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic, or alkaline.
Chemical Bonds - cont’d • Acids and Bases—cont’d • The normal pH of the blood is 7.35 to 7.45. A person with a pH less than 7.35 is acidotic, and a person with a pH greater than 7.45 is alkalotic. • Blood pH is regulated by buffers, the respiratory system, and the kidneys.
Energy • Definition: the ability to do work. • Forms of Energy • The six forms of energy: see Table 2-3. • Most energy is released as heat. • Role of Adenosine Triphosphate (ATP) • ATP is an energy-transfer molecule. • The energy is stored in high-energy phosphate bonds.
Mixtures, Solutions, and Suspensions • A mixture is a blend of two or more substances that can be separated by ordinary physical means. • Solutions, suspensions, and colloidal suspensions are types of mixtures.
Introduction • Anatomy is the study of structure; physiology is the study of function.
The Body’s Levels of Organization • From Simple to Complex • The body is arranged from simple to complex. • Structure and function are related. • Major Organ Systems • An organ system is a group of organs that help each other to perform a particular function.
The Body’s Levels of Organization - cont’d • Major Organ Systems • There are 11 major organ systems. • The integumentary system • The skeletal system • The muscular system • The nervous system • The endocrine system • The circulatory system • The lymphatic system
The Body’s Levels of Organization - cont’d • Major Organ Systems • There are 11 major organ systems—cont’d. • The respiratory system • The digestive system • The urinary system • The reproductive system • Homeostasis refers to the body’s ability to maintain a stable internal environment in response to a changing external environment
Anatomical Terms: Talking About the Body • Anatomical Position • The anatomical position is the body standing erect, arms by the side, with palms facing forward. • Paired terms that describe direction include superior and inferior, anterior and posterior, medial and lateral, proximal and distal, superficial and deep, and central and peripheral. • The three planes are the sagittal plane, frontal (coronal) plane, and transverse plane. • Regional terms are listed in Figure 1-6.
Anatomical Terms: Talking About the Body - cont’d • Cavities of the Body • Dorsal cavity • The cranial cavity contains the brain. • The spinal cavity, or vertebral cavity, contains the spinal cord.
Anatomical Terms: Talking About the Body - cont’d • Ventral Cavity • The thoracic cavity is above the diaphragm and contains the lungs; it also contains the mediastinum. • The abdominopelvic cavity is located below the diaphragm. • The abdominal cavity is the upper part that contains the stomach, most of the intestines, liver, spleen, and kidneys. • The pelvic cavity is the lower part that contains the reproductive organs, urinary bladder, and lower part of the intestines. • For reference, the abdominopelvic cavity is divided into four quadrants and nine regions.