BIOL121 Lecture Notes

Levels of Organisation

  • Anatomy: Study of form, shape, and structure.

  • Physiology: Study of how the body works and the function of body parts.

  • Levels of organization: Atoms > Molecules > Filaments > Cells > Tissues > Organs > Organ Systems > Organism

  • Matter: Solids, Liquids, Gases

  • Major elements in the body: Oxygen, Carbon, Hydrogen, Nitrogen (96% of body mass)

  • Atom: Smallest unit of matter.

  • Element: Collection of the same type of atoms.

  • Atomic Number: Number of protons.

  • Mass Number: Sum of protons and neutrons.

  • Isotopes: Atoms with different numbers of neutrons.

  • Ion: Atom that has gained or lost an electron (charged).

  • Molecule: Two or more atoms sharing electrons via bonding.

  • Compound: Substance containing atoms of two or more different elements.

  • Free Radical: Atom with an unpaired electron.

  • Cation: Atom that has gained an electron.

  • Anion: Atom that has lost an electron.

  • Inorganic Compounds: Usually lack carbon and are structurally simple.

  • Organic Compounds: Always contain carbon, hydrogen, and covalent bonds.

Key Terms

  • Gross Anatomy: Visible to the naked eye (system and surface anatomy).

  • Microscopic Anatomy: Requires a microscope.

  • Cellular Physiology: Properties of living cells.

  • Integrative Physiology: Coordination of activities of different tissues and organs.

The Cell and Cell Membrane

  • Cells: Building blocks, living structures, and functional units of the body.

  • Living Characteristics: Organisation, Cellular composition, Metabolism, Responsiveness, Homeostasis, Development, Reproduction, Evolution

  • Eukaryotic Cells: Defined nucleus.

  • Prokaryotic Cells: No defined nucleus.

  • Somatic Cells: Body cells with 46 chromosomes.

  • Gametes: Sex cells with 23 chromosomes.

  • Stem Cells: Undifferentiated cells with potential to become any cell type.

  • Common Cell Structures: Plasma membrane, cytoplasm, rough and smooth endoplasmic reticulum, ribosomes, golgi apparatus, lysosomes, mitochondria, nucleus

Cell Membrane

  • Separates intracellular fluid (ICF) and extracellular fluid (ECF).

  • Selectively permeable.

  • Contains phospholipids, proteins (peripheral and integral), cholesterol, and glycolipids.

  • Phospholipids: Hydrophilic heads and hydrophobic tails.

  • Cholesterol: Maintains membrane structure and fluidity.

  • Glycolipids: Lipids attached to carbohydrate groups on the outer surface.

  • Membrane Proteins: Act as receptors, enzymes, channels, gated channels, cell identity markers, and cell adhesion molecules.

Components of a Cell and Organelles

  • Cytoplasm: Contains cytosol and protects organelles.

  • Rough Endoplasmic Reticulum: Contains ribosomes; modifies and transports proteins.

  • Smooth Endoplasmic Reticulum: Synthesizes fats and steroids; detoxifies.

  • Ribosomes: Synthesize proteins using amino acids.

  • Golgi Apparatus: Packages secretions for internal and external use.

  • Lysosomes: Contain digestive enzymes; clean up dead materials.

  • Mitochondria: Produce energy (ATP) through cellular respiration.

  • Nucleus: Control center of the cell; contains DNA and instructs protein synthesis.

Movements of Substances Across the Membrane

  • Permeable to small, nonpolar, uncharged molecules (e.g., oxygen, carbon dioxide).

  • Not permeable to large, charged, polar molecules and ions (e.g., glucose).

  • Passive Processes: No ATP required; solutes move down the concentration gradient (simple diffusion, osmosis, facilitated diffusion).

  • Active Processes: Require ATP; solutes move up the concentration gradient (active transport, vesicular transport).

Passive Processes

  • Simple Diffusion: Movement from high to low concentration.

  • Osmosis: Movement of water across a membrane.

  • Isotonic Solution: Equilibrium.

  • Hypotonic Solution: Water moves into the cell.

  • Hypertonic Solution: Water moves out of the cell.

  • Facilitated Diffusion: Uses carrier proteins to transport molecules down a concentration gradient.

Active Processes

  • Active Transport: Requires carrier proteins and moves solutes against the concentration gradient.

  • Vesicular Transport: Uses vesicles to move particles (endocytosis, exocytosis).

Tissues & Homeostasis

  • Four membrane types: Serous, Cutaneous, Mucous, Synovial.

  • Four tissue types: Epithelial, Connective, Muscular, Nervous.

  • Cytology: Study of cells.

  • Histology: Study of tissues.

  • Endocrine glands secrete hormones.

  • Exocrine glands secrete tears, sweat, wax and oils.

Epithelial Tissue

  • Functions: Protection, absorption, filtration, excretion, secretion, surface transport, sensory functions.

  • Locations: Skin, lungs, kidneys, gland organs.

  • Characteristics: Tightly packed cells, little extracellular material, avascular, rapid growth, forms glandular tissue.

  • Classified by: Shape (squamous, cuboidal, columnar) and number of layers (simple, stratified, pseudostratified).

  • Glands: Endocrine (hormones into the body), Exocrine (secretions onto epithelial surfaces through ducts).

Connective Tissue

  • Functions: Supports and binds tissues, insulates, protects, provides immune protection, stores energy, produces heat.

  • Locations: Dense (tendons, ligaments), loose (fat tissue, areolar), liquid (blood, lymph), cartilage, bone.

  • Characteristics: Fewer cells, large amount of extracellular material, mainly vascular.

  • Classified by: Loose (more cells, fewer fibers), dense (more fibers, fewer cells), solid (protection), fluid (transport).

Muscle Tissue

  • Functions: Allows movement, stabilizes joints, controls posture, produces heat.

  • Locations: Skeletal muscles (attached to bones), smooth muscles (organs), cardiac muscles (heart).

  • Characteristics:

    • Skeletal: Voluntary, striated.

    • Smooth: Involuntary, non-striated, fusiform.

    • Cardiac: Involuntary, striated, branched.

  • Classified by: Ability to contract.

Nervous Tissue

  • Functions: Neurons (transmit impulses), Neuroglia (support cells).

  • Location: Throughout the body.

  • Classified by: Ability to conduct messages.

Membranes

  • Mucous: Lines digestive, respiratory, urinary, and reproductive tracts; secretes mucus.

  • Serous: Lines ventral body cavities (peritoneal, pleural, pericardial); double layers with fluid between.

  • Cutaneous: Skin; covers the outer surface of the body.

  • Synovial: Lines joint cavities; produces synovial fluid.

Homeostasis

  • Definition: Ability to maintain a stable internal environment.

  • Components of Feedback System: Receptor, Control center, Effector.

  • Negative Feedback: Response opposes the initial stimulus (most homeostatic mechanisms).

  • Positive Feedback: Response enhances the stimulus (used for large, rapid changes).

  • Key Terms: Squamous (flat), Membranes (epithelial and connective tissues).

Principles of Microbiology

  • Microbiology: Study of microorganisms.

  • Classes of Bacteria: Viruses, Bacteria, Protozoa, Fungi, Helminths

  • Viruses: Very small, not alive, require a host to replicate.

  • Bacteria: Prokaryotes, have cell walls, capable of independent survival, can be cultured.

  • Protozoa: Eukaryotes, single cells, motile, live in fluid/water environments.

  • Fungi, Yeast and Mould: Eukaryotes, cell walls, produce spores.

  • Helminths and Worms: Eukaryotes, multicellular, have organ systems.

Eukaryotes vs. Prokaryotes

  • Eukaryotes: One nucleus, contain organelles, cell wall, mostly multicellular.

  • Prokaryotes: No nucleus, no membrane-bound organelles, cell wall, mostly unicellular, generally smaller.

Bacteria Growth Requirements

  • Temperature, pH, Water, Nutrients, Time, Competition, Oxygen.

  • Normal Flora Bacteria: Regulate digestion and vitamin K production; keep bad pathogens out.

  • Handling Bacteria: Sterilization (killing all traces), Disinfection (reduction to safe level).

Infectious Disease

  • Pathogen: Cause of disease.

  • Virulence: Degree of pathogenicity.

  • Requirements for Disease: Pathogen present, sufficient virulence, sufficient dose, portal of entry/exit, susceptible host.

  • Steps in Infectious Disease: Encounter, entry, spread, multiplication, damage, outcome.

  • Pathogenic Properties: Adherence, invasiveness, evasion, toxins (endotoxins, exotoxins).

Modes of Transmission

  • Contact: Direct, indirect, droplet.

  • Common Vehicle: Airborne, water-borne, food-borne.

  • Vectors:

    • Mechanical: Passive transport on vector's body.

    • Biological: Vector bites host.

  • Portals of Entry: Endogenous (from the body), exogenous (from outside the body).

The Skin

  • Largest organ of body (1.2-2.2 sq meters).

  • Major component of integumentary system.

  • Layers of Skin: Epidermis, Dermis, Hypodermis.

  • Epidermis: Outer layer, epithelial cells, keratinized, avascular.

  • Dermis: Deep layer, connective tissue, collagen, elastin, vascularized, innervated.

  • Hypodermis: Subcutaneous fat layer, anchors skin, stores fat, vascularized.

Skin Colour

  • Melanin: Pigments; UV exposure increases synthesis.

  • Carotene: Yellowish/orange pigment.

  • Hemoglobin: Red pigment.

Nails

  • Figer nail and toe nail.

  • Modifications of the epidermis.

  • Protection of the underlying nerves

Glands

  • Clusters of specialized epithelial cells that secrete substances.

  • Sweat glands and oil glands.

  • Help with temperature regulation and soften skin and hair

Hair

  • Throughout body aside from nipples.

  • Used for warmth and protects from sunburn.

  • Prevents heat loss and detects movement on the skin.

  • Detects insects or things on our skin that could hurt us such as plants.

  • Eyelids prevents dust from coming into their eyes.

  • Eyebrows help to wick the sweat away from the eyes.

Functions of Skin

  • Barrier (Chemical, Physical, Biological),

  • Regulation of body temperature and Cutaenous sensation

  • Production of vitamin D aids in calcium and phosphorus absorption,.

  • Reservoir for blood and Excretion.

The Lymphatic Immune System

  • Lymph: Type of connective tissue.

  • Functions: Drains excess fluid and proteins, defends against threats, transports fats and vitamins.

  • Primary lymphoid tissue: Lymphocytes are formed and mature.

  • Secondary lymphoid tissues: Lymphocytes are activated and cloned.

Components of Lymph System

  • Immune Cells: Lymphocytes (T cells, B cells, NK cells).

  • Lymph Fluid: Fluid connective tissue, similar to plasma but less protein, contains lymphocytes and macrophages.

  • Lymph Vessels: Thin walls, one way movement.

  • Lymph Ducts: Vessels unite to form thoracic ducts.

  • Lymphatic Capillaries: Blind ended tubes.

  • Lymphatic Tissues: Connective tissue dominated by lymphocytes; includes tonsils, adenoids, MALT, Peyer's patches, appendix.

  • Lymphatic Organs: Red bone marrow, thymus, lymph nodes, spleen.

Body Defences

  • First line: Stops antigens from entering.

  • Second line: Stops antigens already in tissue.

  • Third line: Eliminates the antigen.

  • Antigen: Anything foreign to the host (microbes, proteins).

Non-Specific (Innate) Body Defenses

  • First Line of Defense: Skin, mucous membranes, sebum, urine, lysozyme, normal flora.

  • Second Line of Defense: Phagocytosis, fever, inflammation, antimicrobial compounds (leukocytes/WBCs).

Steps of Inflammation

  • Vasodilation, Phagocyte Migration, Repair

  • Signs of inflammation: Redness, pain, heat, swelling, loss of function

Specific Body Defences

  • Acquired or adaptive.

  • Specialist/targeted defenses against one type of antigen.

  • Acquired during life and involve 3rd line defences

Third Line of Defense

  • Specific Immunity:

  • Each B cell or T cell is programmed to act against one invader only.

  • Humoral Immunity: B lymphocytes from stem cell in bone marrow. B cells make antibodies (immunoglobulin).

  • Cell mediated immunity: T cells kills directly (doesnt make antibodies). Works against microbes (inside cell), fungi, transplanted tissue and cancer cells.

Types of Immunity

  • Active Immunity: Body gets the disease and makes own antibodies for life.

  • Active Artificial Immunity: The body gets immunized and makes its own antibodies for life.

  • Passive Natural: Mum's antibodies cross the placenta or in breast milk.

  • Passive Artificial: Give someone antibodies made by someone else to protect temporarily against infection.

Nervous System

  • Functions: Control and transmit sensory, integration, and motor systems.

  • Divisions: Central (brain, spinal cord) and Peripheral (neural tissue outside CNS).

  • Functional Units: Neurons (send/receive signals) and Neuroglia (support/protect neurons).

Nervous System Structure

  • Neurons: Consist of dendrites, cell body, axon, and axon terminals.

  • Neuroglia: Support, nurture, and protect nerve cells.

  • Synapse: Area where a neuron communicates with another cell.

  • Neurotransmitters: Chemicals that transmit messages.

  • Bundle of Fibers: Tract (CNS) vs. Nerve (PNS).

  • Collection of Cell Bodies: Nucleus (CNS) vs. Ganglion (PNS)

  • Myelin Sheath: Insulation that increases speed of transmission.

Nerve Physiology

  • Resting Membrane Potential (Neuron Potential): -70mv (difference between the inside and the outside of the cell)..

  • Action Potential: Change in resting membrane potential, generated by voltage gated ion channels when threshold reached (-55mV).

  • Sodium Potassium pump: Protein that helps ions transfer across the membrane

Structure and function of brain in central nervous system:

  • Cerebrum intellect lobe cognition and movement

  • Diencephalon Thalamus to make motor mupules. Hypothalamus to contro endocrine

  • Cerebellum Controls posture Balance Motor Coordination

  • Brain Stem Controls Respiration

Bones and Joints

  • Functions of Skeletal System: Support, storage, blood cell production, protection, leverage, acid-base balance

Components of the Skeletal System

  • Bones, tendons, ligaments, bone marrow

  • Compact Bone: Strong structure (osteons).

  • Spongy Bone: Distributes stress (trabeculae).

Bone Classification

  • Long, flat, structural, irregular, short, sesamoid

Hormonal Control of Bone Growth

  • Oestrogen is more powerful than testosterone (girls grow faster), testosterone remain higher

  • calcutonin calciuim levels decrease. Growth Hormone during infacty and stimlates bone growth.

Articulation

  • Articulation: A joint or articulation where two or more bones meet.

  • Classification of SynovialJoints.

Muscles

  • Functions: Support movement, stabilize joints, generate heat, store nutrients, guard entrances/exits.

Hormomes

  • Endocrine Hormones: are secreted direction blood streams: exmples are: insilon, glumagon: The contorl center of glands are

Anterior Pitutiary Hormones

  • Human growth hormone regulate byGHRH anfeed back systsems. General Effecto Promote the synthesis of mitosis
    GHRH and GHIH are hypothatlamns hormones. the other Hormons are regulted by hypothalmic control PRH:Prolactin; LH: luteizing; FSH: Folichule Stimating

Posterior Piutiary

Doesnt syntheisiose but stories the homrones to do so Antuduretic Homromones for the Mamary glands. Oxytocin

Pineal Glamd

located in the center of the carpus of the brain. Production by serotonin melatonin to set the biological clock.

Thoroid

locted at the throat to repsonde to the TH. Responds the the TH