Organization of the Human Body

Biology – study of life

Anatomy- study of the structures of the human body and the relationships of the parts (Greek-“cutting up”). Dissection remains a principal technique for teaching anatomy

Physiology- study of the function of the human body

Some branches of anatomy- cytology (study of cells), histology (study of tissues), developmental anatomy (study of changes with aging), embryology (study of anatomy in the first 8 weeks of life), pathology (study of anatomy in disease), gross anatomy (visible to the human eye)

Some characteristics of life- responsiveness (to external environment)

Conductivity (transmission of electrical charges0

Growth (normal increase in size or number of cells)

Respiration (exchange of gases-oxygen and carbon dioxide)

Digestion (breakdown of foods)

Absorption (passing of nutrients from the digestive tract to bodily fluids)

Secretion (production and delivery of substances such as digestive secretions and hormones)

Excretion (removal of waste products including carbon dioxide)

Circulation (movement of body fluids)

Metabolism- (buildup and breakdown of macromolecules)

Reproduction (formation of new individual)

Cells are the basic unit of life. Each is surrounded by a membrane containing cytoplasm, a nucleus, and other organelles. Atoms (see periodic table) form molecules, which form macromolecules which exist in the semifluid cytoplasm. Specialization of cells is called differentiation.

Tissues are layers of similar cells (types include epithelial, connective, muscular, and nervous)

Organs are discrete but functionally complex organization s of different tissues

Organ systems are a group of organs which perform a particular function

Integumentary- or skin protects against microorganisms, maintains body temperature, acts as a sense organ, synthesizes chemicals and hormones. Study of this system is called dermatology.
Skeletal- includes bones are joints. Provides support and allows for movement. Acts as storage for minerals such as calcium and phosphorus
Muscular- causes movement when muscle fibers shorten. Three types are smooth (visceral, involuntary), striated (voluntary, skeletal), and cardiac.
Nervous- one of two regulatory (control) systems. It includes the brain, spinal cord, and nerves
Endocrine- the second control (regulatory) system which uses chemical called hormones that are released by glands into the blood.
Cardiovascular- includes heart and blood vessels. Also called circulatory system
Respiratory includes the lungs and structures that carry air in and out of the lungs. Takes in oxygen and eliminates carbon dioxide (gas waste)
Urinary- includes the kidneys which make urine and the urinary bladder which stores it until it is eliminated as liquid waste
Digestive- also called the gastrointestinal tract) takes in nutrients in the upper digestive tract and eliminates solid waste as feces from the lower digestive tract.
Lymphatic- regulates fluids by collecting excess fluid from the body, filters it to remove microorganisms, and returns it to the heart
Immune- protects from microorganisms
Reproductive- ensures conception and development of offspring

Discuss complementarity of structure and function

Homeostasis- the body maintains temperature and chemical composition within a narrow range that is compatible with life

Directional terms- review axial (head, neck and trunk) vs appendicular (extremities), superior (or cranially; toward the top) vs inferior (toward the bottom), medial (toward the midline) vs lateral (toward the side), ipsilateral (same side), contralateral (opposite sides), superficial (near the surface) vs deep (underneath), anterior (ventral; front/chest surface) vs posterior (dorsal; back), proximal (nearer the trunk) vs distal (farther from the trunk)

Review coronal (divides into front and back), sagittal divides into right and left), and transverse (horizontal, divides into top and bottom) planes

Body cavities- ventral -thoracic (chest) and abdominopelvic vs dorsal -cranial (contains the brain) and dorsal (contains the spinal cord)

The chemical basis of life

Biochemistry is the chemistry of life

Organic Chemistry is the chemistry of carbon- not all biochemical have carbon and not all carbon molecules are present in living things although there is a great deal of overlap

Matter-anything that takes up space and has matter

Substances can be divided into elements or compounds. Elements are puree and cannot be broken down into two or more different substances. Compounds are made or two or more elements.

Atoms (Greek “indivisible”) are composed of protons (+), neutrons (0), and electrons (-)

Atomic number determines the type of element and is the number of protons

Atomic mass or atomic weight is the number of protons plus neutrons.

Changing the number of neutrons makes isotopes. Some, radioisotopes, are naturally unstable

Octet rule- an inert element has 4 pairs of electrons in its outermost shell (electron cloud/electron orbitals). Exceptions are Hydrogen and Helium with a maximum of 2 electrons

Chemical reactions frequently involve pairing of unpaired electrons in outer shells to form molecules

Review periodic table

Atoms are held together by two types of bonds to form molecules. Ionic bonds involve one atom losing an electron and another gaining an electron. Atoms that lose an electron become positively charged ions or cations. Those that gain an electron become negatively charged ions or anions.

Covalent bonds are stronger and involve the sharing of electrons.

Chemical reactions can involve the synthesis, breakdown, or exchange of atoms. They can be reversible or irreversible.

Organic compounds contain C-C and C-H bonds, while inorganic molecules do not

Water makes up about 70% of body weight. Cells contain it in the cytoplasm and are bathed by it in the bodily fluids. The polarity of water makes it the universal solvent. It also gives it a high heat of vaporization which allows one maintain body temperature, by dissipating heat during evaporative cooling during sweating

Oxygen is required for metabolism. Carbon dioxide is a waste gas. Both are inorganic.

Electrolytes are inorganic acids, bases, and salts. Acids release hydrogen ion (H+) in solutions of water and bases (alkaline solutions) take up or accept H+ (acids and bases may be called proton donors and acceptors). Bases increase OH- (hydroxide ions). Strong acids and bases dissociate almost completely in water while weak acids and bases dissociate very little.

pH is a measure of the H+ in a solution.

pH = - log of H+ concentration. pH of 7 is neutral, below 7 is acid, above 7 is basic or alkaline. Each change of 1 pH unit increases the H+ tenfold

Buffers maintain pH by acting as a reservoir of H+

Salts from as the result of neutralization reactions between acids and bases.

Carbon has 4 electrons in the outermost shell so it makes large macromolecules via covalent bonds.

Carbohydrates must have C,H, and O. They provide fuel for the cell and are components of DNA and RNA. They are made of sugars with the chemical formula (CxH2xOx). Names frequently end is –ose. They include monosaccharides (simple sugars for immediate fuel), disaccharides (double sugars) for transport and polysaccharides (or complex sugars). Monosaccharides with a 6C ring are hexoses and those with a 5C ring are pentoses. Water is removed as they are joined in chains of monosaccharides to make larger molecules.
Lipids must contain C, H, and O and act as long-term fuels, as some hormones (steroids), as phospholipids in membranes, as prostaglandins and as waxes. They are oily, hydrophobic molecules and do not dissolve in water
Proteins contain C, H, O, and N and are polymers of amino acids joined by peptide bonds. They are structural (insoluble) proteins or functional (soluble proteins). Of the 20 or so amino acids found most frequently in humans, 8 are essential or cannot be made in the body and must be taken in in the diet. Proteins have a primary (sequence of amino acids), secondary (alpha helix or pleated sheet), and tertiary (bends in the helices or sheets to make a three-dimensional molecule) structure and may have quaternary structure (multiple subunits).
Nucleic acids we will be discussing include ATP (energy source), DNA (genetic material) and RNA. DNA is made of nucleotides with a Nitrogen base, a sugar (deoxyribose) and one of 4 nitrogen bases (A-adenine, C-cytosine, G-guanine and T-thymine). Nucleic acids must have C, H, O, N, and P. RNA has uracil (U instead of thymine, T)

Metabolism is all of the chemical reactions in a cell. Anabolism are reactions that build up large molecules while catabolic reactions break down large molecules to generate ATP. ATP (adenosine triphosphate) stores energy in three high energy bonds P-P-P

Cells

Cells are the basic unit of life. They are separated from the environment with a plasma (cell) membrane that is made of a phospholipid bilayer. (Explain fluid mosaic model for cell membrane). Phospholipids are amphipathic molecules with lipid sides facing each other and phosphate ends facing into the cytoplasm and extracellular fluid. Cholesterol molecules are also found in the membrane as are protein channels for specific molecules. Some proteins may have carbohydrate attachments (glycoproteins) for recognition by the immune system so it does not attack. Other proteins act as receptors for hormones, as enzymes, and to attach cells to one another.

Cytoplasm is gel-like matrix within the membrane. The nucleus and other organelles are found in it.

Nucleus is where the genetic material, DNA, is located. It is separated from the cytoplasm by a nuclear membrane which has pores that allow passage of some molecules.

Membranes (that may be attached to the nuclear membrane) are smooth endoplasmic reticulum (sER) or rough ER. Smooth ER synthesizes lipids (and some carbohydrates) so cells that make a lot of lipids like glands that produce sex steroid hormones or cells that produce fat will have a lot of them. Rough ER has ribosomes to make it rough. Ribosomes are made of ribosomal RNA and act to synthesize proteins.

Golgi can combine, store, and export molecules from the cell. They are C-shaped stacks of membranes near the outside of the cell.

Lysosomes have acid and digestive enzymes to break down waste products and infectious materials in the cell.

Peroxisomes (microbodies) have peroxidase to break down peroxides. This reduces toxins in the cell

Mitochondria have a double membrane separating the inner matrix. The membrane has indentations called cristae. Mitochondria are the powerhouses of the cell, making ATP.

Cytoskeleton-

microfilaments are solid and the smallest. Used for cellular contraction ( examples amoebic motion and muscle contraction)
Intermediate filaments are structural components within the cell. They are different in different tissues and used diagnostically to identify the type of tumor or cancer when it has spread.
Microtubules are hollow tubes and are the largest. They are used to make highways for other molecules to travel on within the cell, and to separate DNA during cell division (spindle fibers). They also make cilia (many short hairlike extensions from a cell) and flagella (a single, long hairlike extension of a cell)

Cell extensions

Cilia (used to move the cell or to move other items along the outside of a cell

Flagella –used to make the cell. In humans only form are sperm. Other flagellated cells are parasites.

Microvilli- invaginations of the membrane that increase surface area in cells specialized for absorption or secretion.

Cell connections-

Desmosomes-have a plaque of proteins material between cells (found in skin)

Tight junctions -membranes overlap- found in intestines

Gap junctions- connect cells to one another in a syncytium- as in heart

Membrane transport through semipermeable membranes

Active transport- always requires energy (ATP). Use to drive molecules UP a concentration gradient

Passive transport- never requires energy (ATP)

Passive transport can be via simple diffusion or facilitated diffusion but can only move molecules down a concentration gradient (from more concentrated to less concentrated)

Simple diffusion- small molecules that pass directly through the cell membrane (such as water, oxygen, carbon dioxide)

Diffusion of water is called osmosis (discuss hypertonic, isotonic, hypotonic-aka, hypoerosmotic..)

Facilitated diffusion requires a protein transporter or channel for molecules to pass. This can regulate (slow) passage but it still does not require ATP.

The best known type of active transport is the Na+K+ATPase which transports K+ into a cell and Na+ out of a cell

Phagocytosis is cell eating or taking in large particles

Pinocytosis is cell drinking or takin in liquids

Endocytosis takes materials into the cell and exocytosis releases materials out of the cell. Phagocytosis and pinocytosis are forms of endocytosis.

DNA is duplicated in the nucleus. It is a double-stranded molecule made of the four nucleotides (ACGT). Each three nucleotides is a triplet and encodes a specific amino acid. The two strands are complementary, with A binding T and C binding G. DNA is used to make RNA in the nucleus in a process called transcription. RNA is used to make proteins on ribosomes in a process called translation. The DNA is on large molecules called chromosomes. When you can see the individual strands they are called chromosomes. When the Chromosomes are duplicated and the duplicates are attached at the center, they are called sister chromatids. When you cannot, it is called chromatin. All of the DNA in a cell is the genome of the cell or individual.

Nuclear division is via meiosis or mitosis

Meiosis Mitosis

One diploid parent cell One diploid parent cell

Duplicates DNA once Duplicates DNA once

Divides twice Divides once

Produces 4 daughter cells Produces 2 daughter cells

Daughter cells are different from parent Daughter cells same as parent

Daughter cells are different from one another Daughter cells same

Daughter cells haploid Daughter cells diploid

Sperm and egg cells (oocytes) only All cells except sperm and egg

Cytokinesis (cell division) follows nuclear division

Stages of mitosis

Prophase- nuclear membranes break down and chromosomes become visible (DNA)

Metaphase-Spindle fibers from centrioles attach to sister chromatids, which line up along the center of the cell (sister chromatids are the duplicate DNA molecules)

Anaphase -sister chromatids are pulled apart by spindle

Telophase- Chromosomes de-condense, nuclear membranes re-form around two nuclei, cytokinesis begins