1

Levels of Organization

Subatomic Particles – electrons, protons, neutronsAtom – hydrogen atom, lithium atom

Molecule – water molecule, glucose molecule

Macromolecule – protein molecule, DNA molecule

Organelle – mitochondrion, Golgi apparatus, nucleus

Cell – muscle cell, nerve cell

Tissue – simple squamous epithelium, loose connective tissue

Organ – skin, femur, heart, kidney Organ System – skeletal system, digestive system

Organism - human

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Levels of Organization

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Anatomy and Physiology

Anatomy – study of structure (Greek – “a cutting up”)

Physiology – study of function (Greek – “relationship to nature”)

Structure is always related to function

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Homeostasis

Body’s maintenance of a stable internal environment

Homeostatic Mechanisms – monitor aspects of the internal environment and corrects any changes

•Receptors - provide information about stimuli

•Control center - tells what a particular value should be (includes a set point)

•Effectors - elicit responses that change conditions in the internal environment

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Homeostatic Mechanisms

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Body Cavities

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Thoracic & Abdominal Membranes

Thoracic Membranes•Visceral pleura•Parietal pleura•Visceral pericardium•Parietal pericardium

Visceral layer – covers an organParietal layer – lines a cavity or body wall

Abdominopelvic Membranes•Parietal peritoneum•Visceral peritoneum

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Serous Membranes

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Serous Membranes

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Table 01.02

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Anatomical Terminology

Anatomical Position – standing erect, facing forward, upper limbs at the sides, palms facing forward

Terms of Relative Position• Superior versus Inferior•Anterior versus Posterior•Medial versus Lateral•Ipsilateral versus Contralateral•Proximal versus Distal•Superficial versus Peripheral•Deep

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Body Sections

•Sagittal / Midsagittal or Median / Parasagittal

•Transverse or Horizontal

•Coronal or Frontal

•Cross section, Oblique, Longitudinal

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Body Sections

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Body Sections

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Body Sections

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Abdominal Subdivisions

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Body Regions

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Major Directional Terms

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Structure of Matter

Matter – anything that takes up space and has weight; composed of elements

Elements – composed of chemically identical atoms• bulk elements – required by the body in large amounts• trace elements – required by the body in small amounts

Atoms – smallest particle of an element

2-3

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Atomic Structure

Atoms - composed of subatomic particles:

• protons – carry a positive charge

• neutrons – carry no electrical charge• electrons – carry a negative charge

Nucleus• central part of atom• composed of protons and neutrons• electrons move around the nucleus 2-4

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Atomic Number and Atomic Weight

Atomic Number • number of protons in the nucleus of one atom • each element has a unique atomic number• equals the number of electrons in the atom

Atomic Weight• the number of protons plus the number of neutrons in one atom • electrons do not contribute to the weight of the atom

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Isotopes

Isotopes• atoms with the same atomic numbers but with different atomic weights• atoms with the same number of protons and electrons but a different number of neutrons• oxygen often forms isotopes (O16, O17, O18)• unstable isotopes are radioactive; they emit subatomic particles

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Molecules and Compounds

Molecules – particle formed when two or more atoms chemically combine

Compound – particle formed when two or more atoms of different elements chemically combine

Molecular formulas – depict the elements present and the number of each atom present in the molecule

H2 C6H12O6 H2O

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Electrons

• found in regions of space called electron shells (energy shells)

• each shell can hold a limited number of electrons• for atoms with atomic numbers of 18 or less, the following rules apply:

• the first shell can hold up to 2 electrons• the second shell can hold up to 8 electrons• the third shell can hold up to 8 electrons

• lower shells are filled first• if the outermost shell is full, the atom is stable

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Ions

Ion• an atom that has gained or lost an electron(s)• an electrically charged atom• atoms form ions to become stable

Cation• a positively charged ion• formed when an atom loses an electron(s)

Anion• a negatively charged ion• formed when an atom gains an electron(s)

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Ionic Bond

• an attraction between a cation and an anion

Ionic Bond

• formed when electrons are transferred from one atom to another atom

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Covalent Bond

Formed when atoms share electrons

•Hydrogen atoms form single bonds•Oxygen atoms form two bonds•Nitrogen atoms form three bonds•Carbon atoms form four bonds

H ― HO = ON ≡ NO = C = O

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Polar Molecules

Polar Molecule• molecule with a slightly negative end and a slightly positive end• results when electrons are not shared equally in covalent bonds• water is an important polar molecule

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Hydrogen Bonds

Hydrogen Bond• a weak attraction between the positive end of one polar molecule and the negative end of another polar molecule• formed between water molecules• important for protein and nucleic acid structure

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Types of Chemical Reactions

Dehydration Synthesis Reaction (Anabolism) – chemical bonds are formed with the removal of water

Hydrolysis/Decomposition Reaction (Catabolism) – chemical bonds are broken with addition of water

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Acids, Bases, and Salts

Electrolytes – substances that release ions in water

Acids – electrolytes that release hydrogen ions in waterHCl H+ + Cl-

Bases – substances that release ions that can combine with hydrogen ions

NaOH Na+ + OH-

Salts – electrolytes formed by the reaction between an acid and a base

NaCl Na+ + Cl-

HCl + NaOH H2O + NaCl 2-17

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Acid and Base Concentrations

pH scale - indicates the concentration of hydrogen ions insolution

Neutral – pH 7; indicates equal concentrations of H+ and OH-

Acidic – pH less than 7; indicates a greater concentration of H+

Basic or alkaline – pH greater than 7;indicates a greater concentration of OH-

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Organic Versus Inorganic

Organic molecules • contain C and H• usually larger than inorganic molecules• dissolve in water and organic liquids• carbohydrates, proteins, lipids, and nucleic acidsInorganic molecules • generally do not contain C• usually smaller than organic molecules• usually dissolve in water or react with water to release ions• water, oxygen, carbon dioxide, and inorganic salts 2-19

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Inorganic Substances

Water • most abundant compound in living material• two-thirds of the weight of an adult human• major component of all body fluids• medium for most metabolic reactions• important role in transporting chemicals in the body• can absorb and transport heat

Oxygen (O2) • used by organelles to release energy from nutrients• necessary for survival 2-20

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Inorganic Substances

Carbon dioxide (CO2)• waste product released during metabolic reactions• must be removed from the body

Inorganic salts• abundant in body fluids• sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.)• play important roles in metabolic processes

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Organic SubstancesCarbohydrates

• provide energy to cells

• supply materials to build cell structures

• water-soluble• contain C, H, and O (CH2O)n

• ratio of H to O to 2:1 (C6H12O6)• monosaccharides – glucose, fructose• disaccharides – sucrose, lactose• polysaccharides – glycogen, cellulose

•subunits linked by glycosidic bonds

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Organic SubstancesCarbohydrates

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Organic SubstancesLipids

• soluble in organic solvents• fats (triglycerides)

• used primarily for energy• contain C, H, and O but less O than carbohydrates (C57H110O6)• building blocks are 1 glycerol and 3 fatty acids per molecule• saturated and unsaturated

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Organic SubstancesLipids

• phospholipids

• building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule

• hydrophilic and hydrophobic

• major component of cell membranes

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phospholipid

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Organic Substances Lipids

• steroids• connected rings of carbon• component of cell membrane• used to synthesize hormones• cholesterol

2-26

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Organic SubstancesProteins

• structural material• energy source• hormones• receptors• enzymes• antibodies• building blocks are amino acids

• amino acids held together with peptide bonds

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Organic Substances Proteins

Four Levels of Structure

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Organic SubstancesNucleic Acids

• constitute genes• play role in protein synthesis• building blocks are nucleotides

• DNA (deoxyribonucleic acid) – double polynucleotide• RNA (ribonucleic acid) – single polynucleotide 2-29

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Organic SubstancesNucleic Acids

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Clinical Applications

Radioactive Isotopes Reveal Physiology

• can be detected in the body using a scintillation counter

• injected into the body

• different types taken up by different organs

• can be used to destroy specific tissues• commonly used

• iodine-131 for thyroid function• thallium-201 for heart function• gallium-67 and cobalt-60 for cancer• others used to assess kidney functions, measure hormone levels and bone density changes 2-31

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Epithelial Tissues-Must Know!

General characteristics

• line body cavities• line hollow organs• have a free surface

• have a basementbasement membranemembrane

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classified according to cell shape and number of cell layers

• cover organs and the body

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Epithelial Tissues-Must Know!

General characteristics

• avascular

• cells readily divide

• cells tightly packed

• cells often have desmosomesdesmosomes

• function in protection, secretion, absorption, and excretion

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Epithelial Tissues

Simple squamous • single layer of flat cells• substances pass easily through• line air sacs• line blood vessels• line lymphatic vessels

Simple cuboidal • single layer of cube-shaped cells• line kidney tubules• cover ovaries• line ducts of some glands

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Epithelial Tissues

Simple columnar •single layer of elongated cells• sometimes possess cilia• sometimes possess microvilli• often have goblet cells• line uterus, stomach, intestines

Pseudostratified columnar•single layer of elongated cells• appear stratified• often have cilia• often have goblet cells• line respiratory passageways

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Epithelial Tissues

Stratified squamous • many cell layers• top cells are flat• can accumulate keratin• outer layer of skin• oral cavity, throat • vagina, anal canal

Stratified cuboidal • 2-3 layers• cube-shaped cells• ducts of mammary glands• sweat glands• salivary glands• pancreas

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Epithelial Tissues

Stratified columnar • top layer of elongated cells• cube-shaped cells in deeper layers• line vas deferens, male urethra, and part of pharynx

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Epithelial Tissues

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Transitional• many cell layers• cube-shaped and elongated cells• line urinary bladder, ureters, and some of urethra

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Glandular Epithelium

Composed of cells that are specialized to produce and secrete substances

Endocrine glands are ductlessExocrine glands have ducts

Unicellular exocrine gland • composed of one cell • goblet cell

Multicellular exocrine gland • composed of many cells• sweat glands, salivary glands, etc.

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Types of Glandular Secretions

Merocrine glands • fluid product• salivary glands• pancreas• sweat glands

Apocrine glands • cellular product• portions of cells• mammary glands• ceruminous glands

Holocrine glands• secretory products• whole cells• sebaceous glands

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Connective Tissues-Must Know

General characteristicsGeneral characteristics

• most abundant tissue type• many functions

• bind structures• provide support and protection• serve as frameworks• fill spaces• store fat• produce blood cells• protect against infections• help repair tissue damage

• have a matrix• have varying degrees of vascularity• have cells that usually divide 5-11

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Connective Tissue Major Cell Types

Fibroblasts• fixed cell• most common cell • large, star-shaped• produce fibers

Macrophages• wandering cell• phagocytic• important in defense

Mast cells• fixed cell• release heparin• release histamine

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Connective Tissue Fibers

Collagenous fibers• thick• composed of collagen• great tensile strength • abundant in dense CT• hold structures together• tendons, ligaments

Elastic fibers• microfibrils embedded in elastin• fibers parallel or branch• elastic• vocal cords, air passages

Reticular fibers• very thin collagenous fibers• highly branched• form supportive networks 5-13

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Connective Tissues

Connective tissue proper• loose connective tissue• adipose tissue• dense connective tissue

Specialized connective tissue• cartilage• bone• blood

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Connective Tissues

Loose connective tissue• mainly fibroblasts• fluid to gel-like matrix• collagenous fibers• elastic fibers• bind skin to structures• beneath most epithelia• between muscles

Adipose tissue• adipocytes• cushions• insulates• store fats• beneath skin• behind eyes• around kidneys and heart

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Connective Tissues

Dense connective tissue• packed collagenous fibers• elastic fibers• few fibroblasts• bind body parts together• tendons, ligaments, dermis• poor blood supply

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Connective Tissues

Bone• solid matrix• supports• protects• forms blood cells• attachment for muscles• skeleton• osteocytes in lacunae

5-17

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Connective Tissues

Cartilage rigid matrix chondrocytes in lacunae poor blood supply three types

1. hyaline2. elastic3. fibrocartilage

1. Hyaline cartilage• most abundant• ends of bones• nose, respiratory passages• embryonic skeleton

2. Elastic cartilage• flexible• external ear, larynx

3. Fibrocartilage• very tough• shock absorber• intervertebral discs• pads of knee and pelvic girdle

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Connective Tissues

Three types of cartilage

5-19

1. Hyaline cartilage 2. Elastic cartilage

3. Fibrocartilage

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Connective Tissues

Blood• fluid matrix called plasma• red blood cells• white blood cells• platelets• transports• defends• clotting• fills blood vessels• heart

5-20

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Muscle Tissues

General characteristics• muscle cells called muscle

fibers• contractile• three types

1. skeletal2. smooth3. cardiac

1. Skeletal muscle• attached to bones• striated• voluntary

2. Smooth muscle• walls of organs• skin• walls of blood vessels• involuntary• not striated

3. Cardiac muscle • heart wall• involuntary• striated• intercalated discs 5-21

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Muscle Tissues

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1. Skeletal muscle 2. Smooth muscle

3. Cardiac muscle

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Nervous Tissues

• found in brain, spinal cord, and peripheral nerves• basic cells are neurons• neuroglial cells are supporting cells• sensory reception• conduction of nerve impulses

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Types of Epithelial MembranesSerous• line body cavities that lack openings to outside• reduces friction• inner lining of thorax and abdomen• cover organs of thorax and abdomen• secrete serous fluidMucous•line tubes and organs that open to outside world•lining of mouth, nose, throat, etc.•secrete mucus

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