Chapter 4 Flashcards
What is tissue
Group of cells that have a common origin in an embryo and function together to carry out specialized atoms
Histology is the science of the study of ______
Tissues
What are the 4 types of tissues
Epithelial, connective, muscular and nervous
Describe the function of epithelial tissue
Covers body surfaces, lines hollow organs, body cavities, ducts and forms glands
Allows body to interact w/ both environments
Describe the function of connective tissue
Protect and support body organs
Binds organs together, stores energy reserve as fats, help provide immunity to disease causing organisms
Describe the function of muscular tissue
Composed of specialized cells for contraction and generates force, generates heat for body
Describe the function of nervous tissue
Detects change in conditions and respond by generating electrical signals (nerve action potentials) that activate contraction and secretions
What are cell junctions ?
Contact points between the plasma membrane of tissue cells
What are the 5 types of cell junctions
Tight junctions
Adherents junctions
Desmosomes
Hemidesmosomes
Gap junctions
What is the structure and function of tight junctions
Structure: weblike strands of transmembrane proteins fused together with outer surface and the plasma membrane, seals off passageways between cells
Function: prevent passage of substances and contents of organs from leaking into the blood and other tissues
What is the structure and function of adherens junctions
Structure: plaque with dense layer of protein inside plasma membrane, attaches to membrane proteins and microfilaments of the cytoskeleton. Transmembrane glycoproteins (called adherins) join cells and insert into the plaque on the opposite side of the plasma membrane and attach aerially cross between cells
Function: help epithelial cell surfaces resist separation during contractile activities
What is the structure and function of desmosomes
Structure: plaques and transmembrane glycoproteins extend into the intracellular space and attach to intermediate filaments (keratin proteins) that extend from one side of the cell across the cytosol to the other side of the cell.
Function: prevent epidermal cells from separating under tension (eg. cardiac muscles during contraction), help cells and tissue stability
What is the structure and function of hemidesmosomes
Structure: transmembrane glycoproteins (integrins) on the inside side of the plasma membrane attach to intermediate filaments (keratin), and attach to laminin on the outside which are present in the basement membrane
Function: anchor cells to the basement membrane
What is the structure and function of gap junctions
Structure: membrane proteins (connexins) form tiny fluid tunnels (connexons) that connect neighbouring cells. The plasma membrane is not fused together, it is separated by an intracellular gap. Ions and small molecules can diffuse from the cytoplasm of one cell to another
Function: transfer nutrients and wastes, allow cells to communicate, enable nerve and muscle impulses to spread rapidly
What are the 3 difference between epithelial tissues and connective tissues
1) number of cells (epithelial are many cells packed together with little or no extracellular matrix , connective have a large extracellular matrix separating cells)
2) blood vessels (epithelial is a vascular, connective had a significant network of vessels)
3) surface (epithelial forms layers and are not covered by other tissues)
What are the 2 types of epithelial tissues
Surface and glandular
What are some general features of epithelial tissue
- covers the lining of surfaces
- form secretion portions of glands
- has to own nerve supply, but is avascular relying on connective tissue blood vessels to bring in nutrients and remove wastes by diffusion
- form boundaries between organs and the body from the external environment meaning it is subjected to physical stress and injury (has high rate of cell division to form/repair itself and replace old/dead cells )
What are the surface structures of epithelium
1- apical (faces the body surface, body cavity, the lumen of an organ, or tubular duct which receives secretions)
2- lateral (faces adjacent cells on either side in tight junctions, adheren junctions, desmosomes or gap junctions)
3- basal (the deepest layer, adhere to extracellular materials like the basement membrane, in hemidesmosomes)
Describe the epithelial tissue structure
Cells arranged into continuous sheets (in single or multiple layers) that are closely packed together by many cell junctions with little intercellular space between adjacent plasma membrane.
Consists of a basal membrane and a reticular lamina as a part of the thin extracellular basement membrane
Describe the basal membrane layer of the basement membrane
The layer that is deeper and secretes epithelial cells. Contains proteins (laminin, collagen, glycoproteins and proteoglycans). The laminin molecules adhere to integrins in hemidesmosomes and attach epithelial cells to the basement membrane
Describe the reticular lamina layer of the basement membrane
Closer to the underlying connective tissues and contains proteins such as collagen produced by connective tissue cells called fibroblasts
What is the function of epithelial tissues
Protect, secrete (mucous, hormones, and enzymes), absorbs (nutrients) and excretes (wastes)
What is the function of the basement membrane of epithelial tissues
Attach and anchor the connective tissue
Form a surface along for epithelial cells to migrate during growth or wound healing
Restrict passage of larger molecules
What’s the difference between endocrine glands and exocrine glands
Endocrine glands: secretions are hormones that enter interstitial fluid and diffuse into the blood
Exocrine glands: secrete into ducts that end up onto a surface that covers/lines epithelium
What are the chances main types of surface epithelium and the difference between them
Simple (single layer and made for exchange of substances ) and stratified (multilayered used for protection )
Surface Simple epithelium functions
A single(for simple) layer used for diffusion, osmosis, filtration, secretion and absorption
What are the 4 types of surface simple epithelium
1) simple squamous (endothelium lines the heart, and vessels of blood and lymph, mesothelioma forms a layer of serous membranes)
2) simple cuboidal
3) simple columnar (non-ciliated and ciliated)
4) pseudostratified columnar (non-ciliated and ciliated)
What is the function of surface stratified epithelium
Has 2 or more layers, that protect underlying tissues where there is significant wear and tear
What are the 4 types of surface stratified epithelium
1) stratified squamous (non-keratinized and keratinized)
2) stratified cuboidal
3) stratified columnar
4) transitional/urothelium (lines the urinary tract)
What are the 2 types of glandular epithelium and what is the main difference between them
Simple (unbranched) and compound (branched)
What are the 5 types of glands of simple glandular epithelium
1) simple tubular (glands of large intestine- secretory part is STRAIGHT, and attached to a single unbranched duct)
2) simple branched tubular (gastric bands- secretory part is BRANCHED and attached to a single unbranched duct)
3) simple coiled tubular (sweat glands- secretory part is COILED and attached to a single unbranched duct)
4) simple acinar (penile urethra gland- secretory portion is ROUNDED and attached to a single unbranched duct)
5) simple branched acinar (sebaceous gland- secretory part is ROUNDED AND BRANCHED and attached to a single unbranched duct)
What are the 3 types of glands of compound glandular epithelium
1) compound tubular (bulbourethral gland- secretory part is TUBULAR and attached to a branched duct)
2) compound acinar (mammary gland- secretory part is ROUNDED and attached to a branched duct)
3) compound tubuloacinar (acinar pancreatic gland- secretory part is TUBULAR AND ROUND and attached to a branched duct)
Exocrine glands classification is differentiated by how secretions are _______, whether the secretion is a ________ of a cell, and consists of an entire glandular cell.
Released
Product
How does the secretory process begin ?
With the ER and Golgi complex working together to form intracellular secretory vesicles that contain the secretory product