Cells and Tissues

Organelles

Internal structures within a cell that perform specific functions.

Nucleus

Contains genetic materials of the cell (DNA) and nucleoli, and serves as the site of RNA synthesis and ribosomal subunit assembly.

Ribosomes

Site of protein synthesis.

Rough Endoplasmic Reticulum

Site of protein synthesis.

Smooth Endoplasmic Reticulum

Site of lipid synthesis and participates in detoxification.

Golgi Apparatus

Modifies protein structures and packages proteins in secretory vesicles.

Lysosome

Digests materials.

Peroxisome

Breaks down fatty acids, amino acids, and hydrogen peroxide.

Mitochondria

Powerhouse of the cell, site of aerobic respiration, and site of ATP synthesis.

Microtubules

Supports cytoplasm and assists in cell division.

Centrioles

Facilitates movement of chromosomes during cell division.

Cilia

Moves substances across the cell surface.

Flagella

Propels the sperm cell.

Microvilli

Increases the surface area of certain cells.

Tissues

A group of specialized cells and extracellular substances sharing a common structure and function.

Epithelial Cells

Tissue that covers and protects body surfaces.

Characteristics of Epithelia

Includes being mostly composed of cells, covering body surfaces, having distinct cell surfaces, possessing cell and matrix connections, being non-vascular, and being capable of regeneration.

Functions of Epithelia

Protecting underlying structures, acting as barriers, permitting the passage of substances, secreting substances, and absorbing substances.

Classifications of Epithelia by Layers

Simple epithelium, stratified epithelium, and pseudostratified columnar epithelium.

Classifications of Epithelia by Cell Shapes

Squamous, cuboidal, and columnar.

Simple Epithelium

A single layer of epithelial cells.

Stratified Epithelium

Multiple layers of epithelial cells.

Pseudostratified Columnar Epithelium

Epithelium appearing stratified due to nuclei at different levels, found in the nasal cavity, sinuses, pharynx, and trachea.

Squamous

Flat, scale-like cells.

Cuboidal

Cube-shaped cells.

Columnar

Tall, column-shaped cells.

Simple Squamous Epithelium

A single layer of flat cells found in the lungs, kidney, and peritoneal cavity.

Simple Cuboidal Epithelium

A single layer of cube-shaped cells found in glands, kidney tubules, bronchioles, and ovaries.

Simple Columnar Epithelium

A single layer of tall cells found in bronchioles, auditory tubes, uterus, and stomach.

Stratified Squamous Epithelium

Multiple layers of flat cells found in the skin, mouth, throat, larynx, esophagus, and anus.

Transitional Epithelium

Stratified epithelium capable of stretching, found in the urinary bladder, ureters, and urethra.

Glands

Secretory organs that can be exocrine or endocrine.

Exocrine Glands

Glands that secrete their products into ducts or onto body surfaces.

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream.

Enclosing and separating other tissues, connecting tissues to one another, supporting and moving parts of the body, storing compounds, cushioning and insulating, transporting, and protecting.

Functions of Connective Tissues

Blast Cells

Cells that produce matrix in connective tissue.

Clast Cells

Cells that break down matrix in connective tissue.

Cyte Cells

Mature cells that maintain matrix in connective tissue.

Loose (Areolar) Connective Tissue

Connective tissue found around glands, muscles, and nerves.

Adipose Tissue

Fat-storing tissue found in mammary glands and all over the body.

Reticular Tissue

Network of fibers found in lymph nodes, spleen, and bone marrow.

Dense Regular Collagenous Connective Tissue

Tissue with parallel collagen fibers found in tendons, ligaments, and skin dermis.

Dense Regular Elastic Connective Tissue

Tissue containing elastic fibers found in vocal cords, intervertebral discs (IVD), and ligaments.

Hyaline Cartilage

Smooth cartilage found in growing bones, cartilages, trachea, and rib cartilage.

Fibrocartilage

Tough cartilage with collagen fibers found in symphysis pubis and articular disks of knees and jaws.

Elastic Cartilage

Flexible cartilage found in external ears, epiglottis, and auditory tubes.

Osseous Tissue

Bone tissue that provides structural support.

Fluid Connective Tissue

Blood tissue responsible for transport throughout the body.

Muscle Tissue

Tissue specialized for contraction and movement, categorized into skeletal, cardiac, and smooth muscle.

Skeletal Muscle Tissue

Voluntary muscle tissue attached to bones for body movement.

Cardiac Muscle Tissue

Involuntary muscle tissue found in the heart.

Smooth Muscle Tissue

Involuntary muscle tissue found in blood vessels, intestines, skin, and eyes.

Nervous Tissue

Tissue specialized for communication and signaling, found in the brain, nerves, and spinal cord.