27 Aug 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
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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
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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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