THE BODY AS A WHOLE. CHAPTER 1: ORGANIZATION OF THE BODY. CHAPTER 2: HOMEOSTASIS. CHAPTER 3: CHEMISTRY OF LIFE. Compose 400 words?or more discussion to respond the following: Define each te

Discussion #1

UNIT 1: THE BODY AS A WHOLE.

CHAPTER 1: ORGANIZATION OF THE BODY.

CHAPTER 2: HOMEOSTASIS.

CHAPTER 3: CHEMISTRY OF LIFE.

Compose 400 words or more discussion to respond the following:

Define each term in these pairs: superior/inferior, anterior/posterior, medial/lateral, dorsal/ventral. What is Anatomical Position? Explain its importance? Describe a example of feed-forward in a physiological control system.

UNIT 1

Chapter 1: Organization of the Body

ANATOMY AND PHYSIOLOGY

  • Anatomy and physiology are branches of biology concerned with the form and functions of the body
  • Anatomy: science of the structure of an organism and the relations of its parts
  • Gross anatomy: study of the body and its parts that relies only on what the eye can see as a tool for observation (Figure 1-2)

ANATOMY AND PHYSIOLOGY (cont.)

  • Microscopic anatomy: study of body parts with a microscope
  • Cytology: study of cells
  • Histology: study of tissues
  • Developmental anatomy: study of human growth and development
  • Pathological anatomy: study of diseased body structures
  • Systemic anatomy: study of the body by systems

ANATOMY AND PHYSIOLOGY (cont.)

  • Physiology: science of the functions of organisms; subdivisions named by:
  • Organism involved: human or plant physiology
  • Organizational level: molecular or cellular physiology
  • Systemic function: respiratory physiology, neurophysiology, or cardiovascular physiology

LANGUAGE OF SCIENCE AND MEDICINE

  • Scientific terms are often based on Latin or Greek word parts
  • A terminology tool is provided in the pull-out section near the front of this textbook
  • Terminologia Anatomica (TA) and Terminologia Histologica (TH)
  • Official lists of anatomical terms (TA, gross anatomy; TH, microscopic anatomy)
  • Terms listed in Latin, in English, and by number
  • Avoids use of eponyms (terms based on a person’s name)
  • Physiology terms do not have an official list but follow the same principles as TA and TH

CHARACTERISTICS OF LIFE

  • A single criterion may be adequate to describe life, such as:
  • Autopoiesis: living organisms are self-organized and self-maintaining
  • Cell theory: if the entity is made of one or more cells, it is alive
  • Characteristics of life considered most important in human beings are summarized in Table 1-1
  • Metabolism: sum total of all physical and chemical reactions occurring in the living body

LEVELS OF ORGANIZATION

  • Chemical level: basis for life (Figure 1-3)
  • Organization of chemical structures separates living material from nonliving material
  • Organization of atoms, molecules, and macromolecules results in living matter—a gel called cytoplasm
  • Organelle level
  • Chemical structures organized to form organelles that perform individual functions
  • Functions of the organelles allow the cell to live
  • Dozens of organelles have been identified, including:
  • Mitochondria
  • Golgi apparatus
  • Endoplasmic reticulum

  • Cellular level
  • Cells: smallest and most numerous units that possess and exhibit characteristics of life
  • Each cell has a nucleus surrounded by cytoplasm within a limiting membrane
  • Cells differentiate to perform unique functions

LEVELS OF ORGANIZATION (cont.)

  • Tissue level
  • Tissue: an organization of similar cells specialized to perform a certain function
  • Tissue cells are surrounded by nonliving matrix
  • Four major tissue types
  • Epithelial
  • Connective
  • Muscle
  • Nervous

LEVELS OF ORGANIZATION (cont.)

LEVELS OF ORGANIZATION (cont.)

  • Organ level
  • Organ: organization of several different kinds of tissues to perform a specific function
  • Organs represent discrete and functionally complex operational units
  • Each organ has a unique size, shape, appearance, and placement in the body

  • System level
  • Systems: most complex organizational units of the body
  • System level involves varying numbers and kinds of organs arranged to perform complex functions (Table 1-2):
  • Support and movement
  • Communication, control, and integration
  • Transportation and defense
  • Respiration, nutrition, and excretion
  • Reproduction and development

LEVELS OF ORGANIZATION (cont.)

  • Organism level
  • The living human organism is greater than the sum of its parts
  • All the components interact to allow the human being to survive and flourish

LEVELS OF ORGANIZATION (cont.)

ANATOMICAL POSITION

  • Reference position (Figure 1-4)
  • Body erect with arms at sides and palms forward
  • Head and feet pointing forward

ANATOMICAL POSITION (cont.)

  • Bilateral symmetry: a term meaning that right and left sides of the body are mirror images
  • Bilateral symmetry confers balanced proportions
  • Remarkable correspondence of size and shape between body parts on opposite sides of the body
  • Ipsilateral structures are on the same side of the body in anatomical position
  • Contralateral structures are on opposite sides of the body in anatomical position

BODY CAVITIES

  • Ventral body cavity (Figure 1-5; Table 1-3)
  • Thoracic cavity
  • Right and left pleural cavities
  • Mediastinum
  • Abdominopelvic cavity
  • Abdominal cavity
  • Pelvic cavity
  • Dorsal body cavity
  • Cranial cavity
  • Spinal cavity

BODY REGIONS

  • Axial subdivision (Figure 1-6; Table 1-4)
  • Head
  • Neck
  • Torso, or trunk, and its subdivisions
  • Appendicular subdivision
  • Upper extremity and subdivisions
  • Lower extremity and subdivisions

BODY REGIONS (cont.)

  • Abdominal regions (Figure 1-7)
  • Right hypochondriac region
  • Epigastric region
  • Left hypochondriac region
  • Right lumbar region
  • Umbilical region
  • Left lumbar region
  • Right iliac (inguinal) region
  • Hypogastric region
  • Left iliac (inguinal) region

BODY REGIONS (cont.)

  • Abdominopelvic quadrants (Figure 1-8)
  • Right upper quadrant
  • Left upper quadrant
  • Right lower quadrant
  • Left lower quadrant

TERMS DESCRIBING BODY STRUCTURE

  • Directional terms (Figure 1-9)
  • Superior and inferior
  • Anterior (ventral) and posterior (dorsal)
  • Medial and lateral
  • Proximal and distal
  • Superficial and deep

TERMS DESCRIBING BODY STRUCTURE (cont.)

  • Terms related to organs
  • Lumen (luminal)
  • Central and peripheral
  • Medullary (medulla) and cortical (cortex)
  • Apical (apex) and basal (base)
  • Many directional terms are listed inside the front cover of the textbook

BODY PLANES AND SECTIONS

  • Planes are lines of orientation along which cuts or sections can be made to divide the body, or a body part, into smaller pieces (Figures 1-9 and 1-10)
  • The three major planes lie at right angles to each other
  • Sagittal plane runs front to back; sections through this plane divide the body (or body part) into right and left sides
  • If section divides the body (or part) into symmetrical right and left halves, the plane is called midsagittal or median sagittal
  • Frontal (coronal) plane runs lengthwise (side to side) and divides the body (or part) into anterior and posterior portions
  • Transverse (horizontal) plane is a crosswise plane that divides the body (or part) into upper and lower parts

HOMEOSTASIS

  • Term homeostasis coined by American physiologist Walter B. Cannon
  • Homeostasis is used to describe the relatively constant states maintained by the body; internal environment around body cells remains constant (Figure 1-13)
  • Body adjusts important variables from a normal set point in an acceptable or normal range
  • Examples of homeostasis:
  • Temperature regulation
  • Regulation of blood carbon dioxide level
  • Regulation of blood glucose level

HOMEOSTATIC CONTROL MECHANISMS

  • Devices for maintaining or restoring homeostasis by self-regulation through feedback control loops
  • Basic components of control mechanisms
  • Sensor mechanism: specific sensors detect and react to any changes from normal
  • Integrating, or control, center: information is analyzed and integrated; if needed, a specific action is then initiated
  • Effector mechanism: effectors directly influence controlled physiological variables
  • Feedback: process of information about a variable constantly flowing back from the sensor to the integrator

HOMEOSTATIC CONTROL MECHANISMS (cont.)

  • Negative feedback control systems
  • Are inhibitory
  • Stabilize physiological variables
  • Produce an action opposite to the change that activated the system
  • Are responsible for maintaining homeostasis
  • Are much more common than positive feedback control systems

HOMEOSTATIC CONTROL MECHANISMS (cont.)

  • Positive feedback control systems
  • Are stimulatory
  • Amplify or reinforce the change that is occurring
  • Tend to produce destabilizing effects and disrupt homeostasis
  • Bring specific body functions to swift completion
  • Feed-forward control systems occur when information flows ahead to another process or feedback loop to trigger a change in anticipation of an event that will follow

HOMEOSTATIC CONTROL MECHANISMS (cont.)

  • Levels of control (Figure 1-14)
  • Intracellular control
  • Regulation within cells
  • Genes or enzymes can regulate cell processes
  • Intrinsic control (autoregulation)
  • Regulation within tissues or organs
  • May involve chemical signals
  • May involve other “built in” mechanisms
  • Extrinsic control
  • Regulation from organ to organ
  • May involve nerve signals
  • May involve endocrine signals (hormones)

CYCLE OF LIFE: LIFE SPAN CONSIDERATIONS

  • Structure and function of body undergo changes over the early years (developmental processes) and late years (aging processes)
  • Infancy and old age are periods when the body functions least well
  • Young adulthood is the period of greatest homeostatic efficiency
  • Atrophy: term to describe the wasting effects of advancing age

,

UNIT 1
Chapters 3: The Chemical Basis of Life and Biomolecules

BASIC CHEMISTRY

  • Elements and compounds (Figure 2-1)
  • Matter: anything that has mass and occupies space
  • Element: simple form of matter; a substance that cannot be broken down into two or more different substances
  • 26 elements are present in the human body
  • Includes 11 major elements, four of which (carbon, oxygen, hydrogen, and nitrogen) make up 96% of the human body (Figure 2-2)
  • 15 trace elements make up less than 2% of body weight
  • Compound: atoms of two or more elements joined to form chemical combinations

BASIC CHEMISTRY: ATOMS

  • Atoms (Figure 2-3)
  • Atomic structure: atoms contain several different kinds of subatomic particles; the most important are:
  • Protons: positively charged subatomic particles found in the nucleus
  • Neutrons: neutral subatomic particles found in the nucleus
  • Electrons: negatively charged subatomic particles found in the electron cloud (Figure 2-4)

BASIC CHEMISTRY: ATOMS (cont.)

  • Atomic number and atomic weight
  • Atomic number (Table 2-1)
  • Number of protons in an atom’s nucleus
  • Atomic number is critically important; identifies the kind of element
  • Atomic weight
  • Mass of a single atom
  • Equal to the number of protons plus the number of neutrons in the nucleus

  • Energy levels (Figures 2-5 and 2-6)
  • Total number of electrons in an atom equals the number of protons in the nucleus (in a stable atom)
  • Electrons form a “cloud” around the nucleus

BASIC CHEMISTRY: ATOMS (cont.)

BASIC CHEMISTRY: ATOMS (cont.)

  • Isotopes (Figure 2-7)
  • Isotopes of an element contain the same number of protons but different numbers of neutrons
  • Isotopes have the same atomic number and therefore the same basic chemical properties as any other atom of the same element, but they have a different atomic weight

BASIC CHEMISTRY: CHEMICAL BONDS

  • Attractions between atoms: chemical bonds
  • Chemical bonds: two types unite atoms into molecules
  • Ionic, or electrovalent, bond: formed by transfer of electrons.
  • Covalent bond: formed by sharing electron pairs between atoms (Figure 2-9)

BASIC CHEMISTRY: CHEMICAL BONDS (cont.)

  • Hydrogen bond (Figures 2-10 and 2-11)
  • Much weaker than ionic or covalent bonds
  • Results from unequal charge distribution on molecules

BASIC CHEMISTRY: CHEMICAL BONDS (cont.)

  • Chemical reactions
  • Involve the formation or breaking of chemical bonds
  • Basic types of chemical reactions are involved in physiology:
  • Synthesis reaction: combination of two or more substances to form a more complex substance; formation of new chemical bonds: A + B  AB
  • Decomposition reaction: breakdown of a substance into two or more simpler substances; breaking of chemical bonds: AB  A + B
  • Exchange reaction: decomposition of two substances and, in exchange, synthesis of two new compounds from them: AB + CD  AD + CB
  • Reversible reactions: occur in both directions

METABOLISM

  • Metabolism: all the chemical reactions that occur in body cells (Figure 2-12)
  • Catabolism
  • Chemical reactions that break down complex compounds into simpler ones and release energy; hydrolysis is a common catabolic reaction
  • The end products of catabolism are carbon dioxide, water, and other waste products
  • More than half the energy released is transferred to adenosine triphosphate, which is then used to perform cellular work (Figure 2-33)

METABOLISM (cont.)

  • Anabolism
  • Chemical reactions that join simple molecules together to form more complex molecules.

ORGANIC AND INORGANIC COMPOUNDS

  • Inorganic compounds: few have carbon atoms and none have C–C or C–H bonds
  • Organic molecules
  • Have at least one carbon atom and at least one C–C or C–H bond in each molecule
  • Often have functional groups attached to the carbon-containing core of the molecule (Figure 2-13)

INORGANIC MOLECULES

  • Water
  • The body’s most abundant and important compound
  • Properties of water (Table 2-2)
  • Polarity: allows water to act as an effective solvent; ionizes substances in solution (Figure 2-10)
  • The solvent allows transportation of essential materials throughout the body (Figure 2-14)
  • High specific heat: water can lose and gain large amounts of heat with little change in its own temperature; enables the body to maintain a relatively constant temperature
  • High heat of vaporization: water requires the absorption of significant amounts of heat to change it from a liquid to a gas; allows the body to dissipate excess heat

INORGANIC MOLECULES (cont.)

  • Oxygen and carbon dioxide: closely related to cellular respiration
  • Oxygen: required to complete decomposition reactions necessary for the release of energy in the body,
  • Carbon dioxide: produced as a waste product and helps maintain the appropriate acid-base balance in the body.

INORGANIC MOLECULES: ELECTROLYTES

  • Electrolytes
  • Large group of inorganic compounds that includes acids, bases, and salts.
  • Substances that dissociate in solution to form ions (resulting ions are sometimes called electrolytes)
  • Positively charged ions are cations; negatively charged ions are anions.

INORGANIC MOLECULES: ELECTROLYTES (cont.)

  • Acids and bases: common and important chemical substances that are chemical opposites
  • Acids
  • Any substance that releases a hydrogen ion (H+) when in solution; “proton donor”
  • Level of acidity depends on the number of H+ a particular acid will release
  • Bases
  • Electrolytes that dissociate to yield hydroxide ions (OH) or other electrolytes that combine with H+
  • Described as “proton acceptors”
  • pH scale: assigns a value to measures of acidity and alkalinity (Figure 2-15)
  • pH indicates the degree of acidity or alkalinity of a solution
  • pH of 7 indicates neutrality (equal amounts of H+ and OH); a pH less than 7 indicates acidity; a pH higher than 7 indicates alkalinity

INORGANIC MOLECULES: ELECTROLYTES (cont.)

  • Buffers
  • Maintain the constancy of pH
  • Minimize changes in the concentrations of H+ and OH
  • Act as a “reservoir” for hydrogen ions
  • Salts (Table 2-3)
  • Compound that results from chemical interaction of an acid and a base
  • Reaction between an acid and a base to form a salt and water is called a neutralization reaction

ORGANIC MOLECULES

  • “Organic” describes compounds that contain C–C or C–H bonds (Figure 2-16; Table 2-4)

ORGANIC MOLECULES: CARBOHYDRATES

  • Carbohydrates: organic compounds containing carbon, hydrogen, and oxygen; commonly called sugars and starches
  • Monosaccharides: simple sugars with short carbon chains; those with six carbons are hexoses (e.g., glucose); those with five are pentoses (e.g., ribose, deoxyribose) (Figure 2-17)
  • Disaccharides and polysaccharides: two (di-) or more (poly-) simple sugars bonded together through a synthesis reaction (Figure 2-18)

ORGANIC MOLECULES: LIPIDS

  • Lipids (Table 2-5)
  • Water-insoluble organic molecules that are critically important biological compounds
  • Major roles:
  • Energy source
  • Structural role
  • Integral parts of cell membranes

ORGANIC MOLECULES: LIPIDS (cont.)

  • Triglycerides or fats (Figures 2-19 and 2-20)
  • Most abundant lipids and most concentrated source of energy.
  • Building blocks of triglycerides are glycerol (the same for each fat molecule) and fatty acids (different for each fat and determine the chemical nature)
  • Types of fatty acids: saturated fatty acid (all available bonds are filled) and unsaturated fatty acid (has one or more double bonds)
  • Triglycerides are formed by dehydration synthesis

ORGANIC MOLECULES: LIPIDS (cont.)

  • Phospholipids (Figure 2-21)
  • Fat compounds similar to triglyceride.
  • One end of the phospholipid is water soluble (hydrophilic); the other end is fat soluble (hydrophobic).
  • Phospholipids can join two different chemical environments.
  • Phospholipids may form double layers called bilayers that make up cell membranes.(Figure 2-22)

ORGANIC MOLECULES: LIPIDS (cont.)

  • Steroids (Figure 2-23)
  • Main component is steroid nucleus
  • Involved in many structural and functional roles
  • Prostaglandins (Figure 2-24)
  • Commonly called tissue hormones; produced by cell membranes throughout the body
  • Effects are many and varied; however, they are released in response to a specific stimulus and are then inactivated

ORGANIC MOLECULES: PROTEINS

  • Proteins (Table 2-6)
  • Most abundant organic compounds
  • Chainlike polymers
  • Amino acids: building blocks of proteins (Figures 2-25 to 2-27)
  • Essential amino acids: eight amino acids that cannot be produced by the human body
  • Nonessential amino acids: 12 amino acids that can be produced from molecules available in the human body
  • Amino acids consist of a carbon atom, an amino group, a carboxyl group, a hydrogen atom, and a side chain

ORGANIC MOLECULES: PROTEINS (cont.)

  • Levels of protein structure (Figure 2-28)
  • Protein molecules are highly organized and show a definite relation between structure and function
  • Protein organization is defined by four levels:
  • Primary structure: the number, kind, and sequence of amino acids that make up the polypeptide chain
  • Secondary structure: polypeptide is coiled or bent into pleated sheets stabilized by hydrogen bonds
  • Tertiary structure: a secondary structure can be further twisted and converted to a globular shape; the coils touch in many places and are “welded” by covalent and hydrogen bonds
  • Quaternary structure: highest level of organization; occurs when protein contains more than one polypeptide chain

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES

  • Nucleic acids and related molecules
  • DNA (deoxyribonucleic acid)
  • Composed of deoxyribonucleotides: structural units consist of the pentose sugar (deoxyribose), phosphate group, and nitrogenous base (cytosine, thymine, guanine, or adenine)
  • DNA molecule consists of two long chains of deoxyribonucleotides coiled into a double-helix shape (Figure 2-31)
  • Specific sequence of more than 100 million base pairs constitutes one human DNA molecule; all DNA molecules in one individual are identical and different from those of all other individuals
  • DNA functions as the molecule of heredity

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

  • RNA (ribonucleic acid) (Figure 2-32; Table 2-7)
  • Composed of the pentose sugar (ribose), phosphate group, and a nitrogenous base
  • Nitrogenous bases for RNA are adenine, uracil, guanine, or cytosine (uracil replaces thymine)
  • Some RNA molecules are temporary copies of segments (genes) of the DNA code and are involved in synthesizing proteins
  • Some RNA molecules are regulatory and act as enzymes (ribozymes) or silence gene expression (RNA interference)

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

  • Nucleotides
  • Nucleotides have other important roles in the body
  • Adenosine triphosphate (ATP) (Figure 2-33)
  • Composed of:

Adenosine

Ribose, a pentose sugar

Adenine, a nitrogen-containing molecule

  • Three phosphate subunits

High-energy bonds present between phosphate groups

ORGANIC MOLECULES: NUCLEIC ACIDS AND RELATED MOLECULES (cont.)

  • Adenosine triphosphate (ATP) (cont.)
  • Energy stored in ATP is used to do the body’s work
  • ATP often called the energy currency of cells
  • ATP is split into adenosine diphosphate (ADP) and an inorganic phosphate group by a special enzyme

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