3.4 Tissues of the Body Flashcards
What are tissues?
Assemblies of cells that perform specific functions in the body.
What is histology?
The study of tissues, focusing on cell shape, size, arrangement, connections, and extracellular material.
What is the extracellular matrix?
Material synthesized and secreted by tissue cells, essential for structure and communication.
what are two components of the extracellular matrix (ECM)?
Proteoglycans and insoluble protein fibres like collagen, fibronectin, and laminin.
What roles does the ECM play?
he ECM plays roles in growth, development, and cell death, with varying composition and consistency affecting tissue properties.
What is the purpose of cell junctions?
Cell junctions hold cells together, enabling tissue formation.
what are the three types of cell junctions?
Gap junctions, tight junctions, and anchoring junctions.
What are tight junctions?
Junctions that create barriers by fusing adjacent cell membranes, regulating movement between external and internal environments.
What are gap junctions?
The simplest form of junctions, allowing direct cell-to-cell communication through channels formed by connexins.
What are the two types of anchoring junctions?
Cell-cell junctions (using cadherins) and cell-matrix junctions (using integrins).
What are anchoring junctions?
Junctions that attach cells to each other or the ECM, providing mechanical strength.
What analogy is used to describe anchoring junctions?
Anchoring junctions are like a picket fence, allowing materials to pass between cells (paracellular pathway).
What are desmosomes?
The strongest cell-cell junctions, attaching to intermediate filaments of the cytoskeleton; can be spot or belt desmosomes.
What are hemidesmosomes?
Junctions that anchor intermediate fibres of the cytoskeleton to fibrous matrix proteins like laminin.
What is the function of epithelia?
Epithelial tissues protect the internal environment and regulate material exchange between internal and external environments.
What are the types of epithelial tissues?
Exchange epithelia, transporting epithelia, ciliated epithelia, protective epithelia, and secretory epithelia.
What is the difference between endocrine and exocrine glands?
Endocrine glands are ductless and release hormones into the bloodstream, while exocrine glands secrete products to external environments via ducts.
Define secretion.
The process by which substances are produced and released by cells, particularly in secretory epithelia.
What is the structure of epithelia?
Epithelia consist of one or more layers of cells connected by junctions, with a basal lamina separating them from underlying tissues.
Where are leaky epithelia found?
In capillaries, where molecules can pass through gaps between cells, excluding large proteins.
Where are transporting epithelia primarily found?
in the digestive tract and kidneys, where they regulate the exchange of ions and nutrients.
What is the function of ciliated epithelia?
Ciliated epithelia move fluid and particles across their surface, found in the respiratory system and reproductive tract.
