Module 1 - Epithelial and Connective Flashcards
The epithelial surface that is exposed, or free, away from the underlying connective tissue, is the ___________ surface.
Apical
Select all of the following that correctly describe features of epithelial tissues.
-Epithelial tissue is composed of a sheet of cells at least one layer thick.
-The basal surface of epithelium is tightly bound to a basement membrane.
-Once a cell is damaged or lost, it is not capable of regeneration.
-Epithelial tissue is highly vascularized, with many blood vessels directly supplying it.
-Epithelial tissue cells are all the same in both size and shape.
-Epithelial tissues are composed almost entirely of cells tightly bound to each other with little extracellular substance.
-Epithelial tissue is composed of a sheet of cells at least one layer thick.
-The basal surface of epithelium is tightly bound to a basement membrane.
-Epithelial tissues are composed almost entirely of cells tightly bound to each other with little extracellular substance.
T/F: The apical surface of epithelium has the same structure and function as the basal aspect of the epithelium.
False
What serves to increase the surface area of the apical aspect of an epithelial cell for absorption.
Microvilli
Which of the following is a general function of epithelial tissue?
1. Produce secretions through glandular epithelial cells.
2. Selectively control the substances that can cross through the epithelium.
3. Specialized epithelial cells can detect light, taste, smell, and other senses.
4. Fill spaces between structures of the body.
5. Protection of external or internal surfaces from chemical or biological agents.
6. Contract to move the bones and joints of our body.
1, 2, 3, 5
_______ are found on the apical surface of epithelial cells and beat in unison to move substances across the surface of the epithelium.
Cilia
What term means two or more layers?
Stratified
Simple Cuboidal
Single layer of cells with equal height and width; absorption and secretion
Stratified Squamous
Two or more layers of cells. The apical cells are flat in shape.
Simple Squamous
A single layer of flat cells; performs simple diffusion
Transitional
Able to stretch as needed and return to its original form.
Simple Columnar
A single layer of cells that are taller than they are wide; absorption and secretion
Pseudostratified Squamous
All cells touch the basal surface but only some cells reach the apical surface.
Simple Squamous
Found in places where we need substances to move rapidly and easily through the epithelium.
Stratified Squamous
Found in places where we need protection against abrasive forces; protection
Pseudostratified columnar
appears to have multiple layers of cells due to the varying heights of its columnar cells, but is actually composed of a single layer where all cells are attached to the basement membrane; secretion and surface parallel transport
Which type of epithelium would be present where easy exchange of materials out of the blood is most important?
Simple Squamous
Which type of epithelium always contains cilia on its apical surface?
Pseudostratified columnar
How do epithelial cells exhibit polarity?
They have differences in structure and function between the exposed or apical surface of the cell, the free surface away from underlying tissue, and the basal surface attached to the underlying tissue.
Basal surface
Bottom layer of epithelial tissue attached to basement membrane.
Basement membrane
sits just below the basal surface of epithelial cells and anchors the cells to the underlying tissue
What two layers is the basement membrane formed of?
the basal lamina, which attaches to the basal aspect of the cells, and the reticular lamina, which is attached to the underlying connective tissue.
Apical surface
Top layer of epithelial tissue exposed to environment.
What are the two apical features and what are their functions?
Cilia: Hair-like structures aiding in movement across epithelial surfaces (aid in surface parallel transport)
Microvilli: extensions that serve to increase the surface area of the apical aspect of the cell for absorption.
Tight junctions
Seal between adjacent epithelial cells preventing leakage; enables the epithelia to act as a selective barrier.
Adhering junctions
prevents the cells from being pulled apart; holding the epithelial cells together for support and stability of the tissue.
Desmosomes
Anchoring junctions that prevent cells from being pulled apart; provide support and stability of the tissue.
Gap junctions
Forms an intercellular passageway between the membranes of adjacent cells to facilitate the movement of small molecules and ions between the cytoplasm of adjacent cells. These junctions allow electrical and metabolic coupling of adjacent cells, which coordinates function in large groups of cells.
Selective permeability
The cells of an epithelium act as gatekeepers of the body controlling permeability and allowing selective transfer of materials across a physical barrier. All substances that enter the body must cross an epithelium
Surface parallel transport
Transport of substances across the free surface of the epithelium.
Transcellular transport
absorption of substances through the cell, where it is processed to some degree before being released into the blood and/or underlying tissue.
Are epithelial tissues vascular or avascular?
Avascular; they receive nutrients by diffusion or absorption from the underlying tissues or occasionally from substances on the surface.
Are epithelial tissues capable of regeneration?
Yes, they can rapidly replace dead cells.
Simple
A single layer of cells, with every cell resting on the basal lamina of the basement membrane
Stratified
More than one layer of cells, with only the basal layer resting on the basal lamina of the basement membrane. This can be just a few layers or dozens of layers depending on the location.
Squamous
Flattened and thin
Pseudostratified
Only one layer of cells, but the height of the cells vary, giving the appearance of more than one layer (pseudo- = false). Only some of the cells have an apical surface that reaches the free surface of the epithelium.
Metaplasia
normal epithelia from one area replaced by another form of epithelia not typical for that region - can happen when cells are irritated or responding to injury
Glands
a structure made up of one or more cells modified to synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells, though some cells themselves are considered glands. Perform a secretory function: Mucin, hormones, enzymes, and waste products
Endocrine glands
-a ductless gland that releases hormones directly into surrounding tissues and bloodstream (endo- = “inside”)
-highly vascularized
-Hormones can only affect target cells that have receptors for that specific hormone
Humoral secretion
When an endocrine gland releases a hormone in direct response to changing ion or nutrient levels in the blood
Neural secretion
nerve cell synapses with endocrine cell; neurotransmitter release triggers secretion of hormone
Hormonal secretion
Stimuli received from other glands, certain hormones signal secretion of other hormones
Exocrine glands
-secretions leave through a duct that opens directly, or indirectly, to a surface (e.g. skin, digestive tract, respiratory tract; exo- = “outside”)
Goblet cells
-a unicellular exocrine gland that produces mucin that protects and lubricates many internal body surfaces
-interspersed between the columnar or pseudostratified columnar epithelial cells of mucous membranes
Mucin
becomes mucus when mixed with water; protective
Elastic fibers
These fibers contain the protein elastin along. The main property of elastin is that after being stretched or compressed, it will return to its original shape
Collagen fibers
Collagen fibers, while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the movement of the body.
Reticular fibers
Reticular fibers are found throughout the body, but are most abundant in the reticular tissue of soft organs, such as liver and spleen, where they anchor and provide structural support to the organ while allowing space for blood and cells to move through the structure.
Connective tissue proper
-the largest category of connective tissue. The primary cell type of connective tissue proper is the fibroblast, which secretes the ground substance and protein fibers in the extracellular matrix.
-Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers (embedded in ground substance)
-can be further subdivided into loose connective tissue and dense connective tissue.
Loose connective tissue
-found between many organs where it acts both to absorb shock and bind tissues together.
-areolar, adipose, reticular
Areolar connective tissue
-contains all the cell types and fibers distributed in a random, web-like fashion, highly vascular, and function is to fill spaces
Adipose connective tissue
-contains adipocytes (fat cells), highly vascular, and functions as insulation, energy, water, and hormone storage, as well as support and protection of the organs
Reticular connective tissue
network of reticular fibers in loose ground substance and forms a soft, supportive framework for soft organs – scaffolding
Dense connective tissue
contains more collagen fibers than does loose connective tissue. As a consequence, it displays greater resistance to stretching
Dense regular connective tissue
Parallel thick collagen fibers, enhances tensile strength and resistance to stretching in ONE direction (direction of fiber orientations) (ex. tendons)
Dense irregular connective tissue
Mainly thick collagen fibers in a random arrangement; gives tissue more strength to withstand tension in ALL directions (ex. dermis)
Elastic connective tissue
contains elastin fibers in addition to collagen fibers, which allows the tissue to return to its original length after stretching (stretch and recoil) (ex. ligaments that form vocal cords and walls of large blood vessels)
Ground substance
unstructured material that fills the space between the cells and contains the fibers
Extracellular matrix
where CT cells are dispersed; substance surrounds the cells
Neoplasia
Abnormal growth of tissue, potentially forming tumors.
Necrosis/Apoptosis
Cell death
Secretion
Many epithelial cells are capable of producing and secreting specific chemical compounds onto their apical surfaces.
Sensation
Specialized epithelia can detect light, taste, sound, smell, and hearing.
Protection
Epithelial tissues provide the body’s first line of protection from physical, chemical, and biological wear and tear.
What are the 7 functions of epithelial tissue?
-Protection
-Selective permeability
—> Diffusion
—>Absorption (Transcelluar transport)
-Secretion
-Sensation
-Surface parallel transport
