Lecture 1 Cells, Tissues & Body organisation

Basic Organisation of the Body

  • Five levels of body organisation:

  • Cells: smallest functional unit

  • Tissues: multiple cells

  • Organ: tissues make up organ

  • Organ system: multiple organs working together

  • Organism: multiple organ systems that make up the body

    • Humans have approximately 210 different cell types.

Components of Cell Theory

  1. All living organisms consist of one or more cells.

  2. Cells are the basic unit of structure and function.

  3. New cells arise only from existing cells.

Light Microscopy Observations

  • Various cellular structures visible in blood and duodenum tissues.

  • blood cells carry oxygen

  • extracellular matrix = extracellular (not in the cell) matrix (complicated cell)

  • cytoplasm (plasm = water)

Advanced Microscopy Techniques

  • Scanning Electron Microscopes (SEM):

    • Equipment examples: KIMTECH, FEI, TECHAIS

Cellular Structures

  • Organelle (smaller organs inside cells, nelle = smaller version of something)

  • Major organelles include:

    • Nucleus

    • Cell membrane

    • Mitochondria

    • Golgi apparatus

    • Endoplasmic reticulum

    • Ribosomes, Lysosomes, Peroxisomes, etc.

Functions of Cellular Structures

  • Cell Membrane:

    • Phospholipid bilayer, regulates movement in/out of cells. has hydrophobic and hydrophilic regions

    • regulates what goes in and out of cell

    • Heads of phospholipid bilayer - hydrophilic - water loving heads

    • Tails of bilayer are hydrophobic

    • Creates a barrier that prevents water inside of the cell from leaving and water outside of the cell from coming in

    • Has proteins embedded in that regulate what comes in and out - protein channel - proteins have receptors to communicate with each other

  • Nucleus:

    • Control center, contains DNA (chromatin), and nucleolus for ribosome production.

    • DNA contains recipe to make proteins

    • Nucleolus produces ribosomes

    • DNA copied into mRNA to pass messages out of the nucleus

Cytoplasm & Nucleoplasm

  • Gel-like fluids that contain dissolved molecules important for cell functions.

  • impairment of solute and solution levels can damage the cell

Endoplasmic Reticulum (ER)

  • endo = inside, plasmic = water, reticulum = many pathways

  • ER: folded membranous structure that surrounds nucleus

  • Types:

    • Rough ER (with ribosomes embedded on inner part of membrane) for protein production - mRNA sends recipes to ribosomes which build proteins

      • ribosomes build proteins from RNA code

    • Smooth ER (without ribosomes) for folding and packaging of proteins.

      • folds and packs into membrane bound pouches - vesicles

Golgi Apparatus

  • Processes and modifies amino acid chain from the ER, functioning as the "postal service" of the cell.

  • repackages and sends proteins in membrane bound packages out of the cell - membrane merges with same material membrane

Mitochondria

  • Produces energy (ATP) through the breakdown of carbohydrates, lipids, and proteins.

  • ATP is energy that maintains cell function

  • energy used by nerve cells to remove water from the cells - not enough energy means cell death

Common Characteristics of Cells

  • Functions necessary for life include:

    • Obtaining nutrients

    • Waste disposal

    • Maintaining shape and integrity

    • Undergoing cell division (mitosis/meiosis)

      • mitosis: one cell splitting into two identical cells - replicating itself - used by bacteria

      • meiosis: creates gametes - anything that sexually reproduces uses meiosis

Tissues

  • Histology: Study of cells and extracellular matrix; four tissue types:

    1. Epithelium

    2. Connective

    3. Muscle

    4. Nervous

Epithelium Characteristics

  • Covers body surfaces and cavities, acts as protective layers (e.g., skin, lining of organs (kidney cells, liver cells, inside of mouth).

  • stops things from drying out

  • separates, protects and helps keep organs in place

  • Cell shapes include:

    • Squamous: Flat

    • Cuboidal: Cube-shaped

    • Columnar: Rectangular

Layer terms of epithelium and function

  • Layer Terms:

    • Simple: one layer

    • Stratified: multiple layers

    • Pseudostratified: appears like multiple layers but is one.

  • Functions:

    • simple squamous epithelium = gas and/or nutrient exchange

    • stratified squamous epithelium = protection

    • simple and stratified cuboidal epithelium = absorption and/or secretion

    • simple, stratified and pseuodostratified columnar epithelium = absorption and/or secretion

Connective Tissue

  • Functions: Support and structure; high extracellular matrix ratio (bones, cartilage, fat, blood).

  • most abundant tissue in the body

  • high extracellular to cell ratio

  • bone and cartilage are connective tissue types

Nervous & Muscle Tissues

  • Nervous Tissue: Transmits sensory and motor signals - brain signals go through nervous tissue.

    • coordinates functions

  • Muscle Tissue: Enables movements; includes skeletal, cardiac, and smooth types.

    • Skeletal muscle tissue: consciously think and move - the single tubes that merge together in one line eg.biceps

    • Smooth muscles: cant think about/control eg. digestive tract, gastrointestinal tract, lungs, blood vessels, intestines.

    • Cardiac muscle: squeezes and is branched, has stripes to enable contracting function - shorter/longer

Organs and Organ Systems

  • Composed of different tissue types working together to perform specific functions (e.g., heart, lungs).

Major Organ Systems

  • 11 principal systems include:

    • Cardiovascular, Respiratory, Nervous,

    • Integumentary, Gastrointestinal, Renal,

    • Secretory, Muscular, Skeletal,

    • Reproductive, Lymphatic/Immune systems.

Anatomical Position & Planes of Division

  • Anatomical positioning is standardized for consistency in identification.

  • Planes:

  • Major cavities within the torso:

    • Thorax (chest to diaphragm)

    • Abdomen

    • Pelvis

    • Dorsal/spinal

Medical Terminology