Cellular and Tissue Biology: An Overview
Atom: Chemical parts, mainly carbon, hydrogen, oxygen, and nitrogen.
Molecules: Components from cells that form structures, including proteins, carbohydrates, and lipids, transported through cells and the bloodstream.
Cell: The basic unit of living beings, capable of manufacturing its own components.
Bone: A collection of cells.
Body: Formed by different tissues with specific functions.
Apparatus or System: An association of organs working together to perform a vital function.
Homeostasis: The balance that maintains a constant internal environment within an organism.
Nervous/Endocrine System: Coordinates all regulatory mechanisms.
Structure of a Cell
Cell Membrane: The outer membrane.
Cytoplasm or Plasma Membrane: The space between the plasma membrane and nuclear membrane, containing the cytoskeleton and organelles like ribosomes.
Nucleus: The most prominent cellular structure.
Nuclear Components
Contains the information necessary for cell function and reproduction, known as genetic information. Its interior contains nucleoplasm built from DNA.
DNA: DNA molecules found as shaped chromosomes during cell division.
Gene: A portion of DNA containing the genetic information necessary to make a protein.
Parts of the Cell
- Cell Membrane: Area of contact with the exterior.
- Cytoplasm: Contains organelles, including proteins, endoplasmic reticulum, Golgi apparatus, and lipids.
- Mitochondria: Produce energy from cellular glucose.
- Cytoskeleton: Maintains cell shape and elasticity, containing enzymes.
- Lysosome-Golgi Apparatus: Transports and modifies proteins to the exterior of the cell.
- Ribosomes: Manufacture proteins from nuclear DNA.
- Directs cell activity by informing DNA.
Bone Tissue
Formed by an intercellular substance and similar cells.
Epithelial Bone Tissue
Responsible for protection, absorption, excretion, filtration, and secretion. Lacks blood vessels.
Glandular Tissue
Glands can be endocrine (secrete products directly into the blood), exocrine (secrete products into foreign or digestive tubes), or mixed.
Connective Bone Tissue
The most abundant tissue, supporting other tissues, merging and protecting internal organs. Formed by cells called fibroblasts and an extracellular matrix reinforced by fibers.
- Loose Connective Tissue: Extends throughout the body with high resistance and density due to collagen fibers.
- Cartilage: Formed by a gelatinous matrix of collagen and elastic fibers.
- Bone: A very tough matrix impregnated with mineral salts.
- Blood: A liquid matrix, plasma, and blood cells.
Nervous Tissue
Formed by two types of cells: neurons and glial cells.
Neurons
The functional unit of the nervous system, connecting and transmitting information to other cells.
- Basic Structure: Cell body (nucleus and cytoplasm).
- Dendrites: Receive information.
- Axon: Transmits information.
Information always travels from dendrites to axons. The axon is nervous.
Glial Cells
Provide support to neurons.
- Astrocytes: Most abundant in the central nervous system.
- Microglia: Function in protection and defense of neurons against noxious substances.
- Schwann Cells: Found in the peripheral nervous system.
Muscles
Change bone length and are formed by muscle fibers capable of contracting upon nervous system stimulation.
- Skeletal muscle
- Smooth muscle
- Cardiac muscle