Unit 1-4

UNIT 1: INTRODUCTION TO ANATOMY

A) What is Anatomy?

  • Definition: Study of internal and external body structures and their relationships.

  • Subdivisions:

    1. Microanatomy: Requires a microscope.

      • Cytology: Study of cells.

      • Histology: Study of tissues (groups of cells).

    2. Gross Anatomy: Structures visible to the naked eye (e.g., bones, heart, stomach).

      • Study of body cavities: cranial, thoracic, abdominopelvic.

B) Levels of Organization (simple to complex)

  1. Chemical Level:

    • Basic level consists of atoms (e.g., Hydrogen and Oxygen).

    • Atoms join to form molecules (e.g., H2O).

  2. Cellular Level:

    • Molecules form organelles, which make up cells.

    • Cells are the basic units of structure and function.

    • Different cell types (e.g., erythrocytes, neurons, muscle cells).

  3. Tissue Level:

    • Group of structurally similar cells with a common function.

    • Four major types of tissues:a) Epithelialb) Connectivec) Muscled) Nervous

  4. Organ Level:

    • Consists of two or more tissues working together for a common function.

    • Example: Stomach is composed of all four major tissue types; its function is digestion.

  5. Organ System Level:

    • Several related organs worked together to accomplish a common purpose (e.g., respiratory system includes lungs and trachea; function is respiration).

  6. Organism Level:

    • All systems function together to maintain life.

    • Note: This is a hierarchy; each level contains those below it.

UNIT 2: CHEMICAL LEVEL OF ORGANIZATION

A) Structure of an Atom

  • Defined as the basic building block of matter, including all parts of the human body.

  • Atoms consist of three subatomic particles:

    1. Protons: Positively charged particles found in the nucleus.

    2. Neutrons: Neutral particles found in the nucleus.

    3. Electrons (e-): Negatively charged particles orbiting the nucleus.

  • Atoms are electrically neutral when the number of protons equals electrons. Neutrons may not be equal, leading to isotopes.

B) Ions

  • When an atom loses or gains electrons, it becomes an ion.

    • Anion: Atom that gains electrons (negatively charged).

    • Cation: Atom that loses electrons (positively charged).

  • Important ions (electrolytes):

    • Calcium: Ca2+

    • Sodium: Na+

    • Potassium: K+

    • Hydrogen: H+

    • Chloride: Cl-

C) Chemical Bonds

  • Bonds hold atoms together to form molecules.

Types of Bonds:

  1. Ionic Bond:

    • Involves transfer of electrons (e.g., NaCl).

    • Forms when cations and anions attract each other.

  2. Covalent Bond:

    • Involves sharing of electrons (e.g., O2).

D) Water (Inorganic)

  • Most abundant substance in cells, composed of two hydrogen atoms and one oxygen atom.

  • Exhibits polar nature due to unequal sharing of electrons.

  • Functions:

    • Universal solvent for biological reactions.

    • Transports chemicals (e.g., O2, nutrients).

    • Maintains body temperature (~37°C).

E) Acids and Bases

  • Play a critical role in maintaining pH balance:

1. Acids:

  • Dissociate in H2O releasing H+ ions.

  • ↑[H+] = ↓pH (more acidic).

  • Example: HCl → H+ + Cl-

2. Bases:

  • Substances that bind to free H+ ions (i.e., they increase pH).

  • Example: NaOH → Na+ + OH-

F) Important Organic Substances

  1. Carbohydrates:

    • Composed of C, H, and O (formula: (CH2O)n).

    • Serve as energy sources and structural materials.

    • Types include monosaccharides, disaccharides, and polysaccharides.

  2. Lipids:

    • Composed of C, H, and O (different ratio than carbohydrates).

    • Functions include protection, cell membrane structure, and energy storage.

    • Types include triglycerides, phospholipids, and steroids.

  3. Proteins:

    • Made up of C, H, O, N (and sometimes S).

    • Functions as structural materials, enzymes, hormones, antibodies, and energy sources (when needed).

    • Comprised of amino acids, forming peptides and proteins.

  4. Nucleic Acids:

    • Composed of C, H, O, N, and P.

    • Forms include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

    • Functions in genetics and protein synthesis.

  5. Adenosine Triphosphate (ATP):

    • Functions as the energy currency of cells, storing energy in covalent bonds.

UNIT 3: CELLULAR LEVEL OF ORGANIZATION

A) The Cell

  • Defined as the basic structural and functional unit of the body, capable of performing all basic life functions.

B) Principal Parts of the Cell

  1. Cell Membrane/Plasma Membrane:

    • Acts as a boundary between the inside and outside of the cell.

    • Composed of a phospholipid bilayer, cholesterol, membrane proteins, and carbohydrates.

  2. Cytoplasm:

    • Area between the cell membrane and nucleus, containing cytosol and organelles.

  3. Nucleus:

    • Largest membranous organelle serving as the cell control center.

C) Cell Membrane Structure

  1. Phospholipid Bilayer:

    • Phosphate head groups (hydrophilic) and fatty acid tails (hydrophobic).

  2. Membrane Proteins:

    • Integral proteins (inserted in membrane) and peripheral proteins (attached to the surface).

    • Functions: enzymes, transporters, channels, receptors, anchors, identity markers.

  3. Membrane Carbohydrates:

    • Present on the outer surface, aiding in cell recognition and anchoring cells together.

D) Cytoplasm

  • Composed of cytosol and various organelles:

1. Cytosol:

  • Gel-like fluid containing water, ions, and organic molecules.

2. Organelles:

  • Included in non-membranous and membranous categories.

  • Examples: ribosomes, mitochondria, Golgi apparatus, lysosomes.

E) Nucleus Components

  1. Nuclear Envelope:

    • Double membrane with pores, connected to the endoplasmic reticulum.

  2. Nucleolus:

    • Non-membranous region where ribosomes are made and assembled.

  3. Chromosomes:

    • Made of DNA and histone proteins, existing as chromatin (uncoiled) or condensed during cell division.

UNIT 4: THE CELL CYCLE, MITOSIS, MEIOSIS

A) Cell Types

  1. Gametes (n):

    • Haploid cells (23 chromosomes) include ova and sperm.

  2. Somatic Cells (2n):

    • Diploid (46 chromosomes), includes all other body cells, arranged in homologous pairs.

B) Cell Cycle

  • Comprises interphase and mitotic phase:

  1. Interphase (G1, S, G2 phases)

    • G1: Growth and metabolism, centrosome replication begins.

    • S: Chromosome replication, forming sister chromatids.

    • G2: Growth, metabolism, and preparation for cell division.

  2. Mitotic Phase:

    • Includes mitosis (nuclear division) and cytokinesis (cytoplasm division).

C) Mitosis Phases

  1. Prophase: Chromosomes condense, nuclear envelope breaks down.

  2. Metaphase: Chromosomes align at the cell equator.

  3. Anaphase: Sister chromatids separate and move to opposite poles.

  4. Telophase: Nuclear envelope reforms, chromosomes decondense.

D) Meiosis Process

  • Results in formation of four genetically unique haploid gametes from one diploid cell.

  • Involves two rounds of division: Meiosis I and Meiosis II.