Tissues Chapter 4 Anatomy and P Lecture
simple vs. complex glands
A simple gland has an unbranched duct (or no duct at all A compound gland has a branching duct.
unicellular
(mucous cells & goblet cells) - secrete via exocytosis - Intestinal tract, resp tract - Secretions: mucin/mucus
multicellular
(structurally complex) - Simple vs Compound - Secretory units: tubular, alveolar, both - Secretion: merocrine, holocrine, apocrine
What characteristic does cartilage have in common with epithelial tissue? Why isn't cartilage classified as an epithelial tissue? If cartilage heals slowly, why doesn't epithelial tissues also heal slowly?
Cartilage and epithelial tissues are both avascular. Cartilage has extensive extracellular matrix and is derived from mesenchyme, so it is classified as a connective tissue. Cartilage cells lose their ability to divide, while epithelial cells do not, accounting for the difference in healing capacity between the two tissues.
Cells in connective tissue
Cells - Fibroblast/Fibrocyte • Connective tissue proper - Chondroblast/Chondrocyte • Cartilage - Osteoblast/Osteocyte • Bone - Adipocytes - White Blood Cells • Neutrophils, Eosinophils, Lymphocytes - Mast Cells - Macrophages
connective tissue functions
Derive From Mesenchyme Extensive Extracellular Matrix: A lot of extracellular room. The extracellular matrix is made of: Some # of cells (find cells depending on tissue); Fibers (Collagen. Elastic, Reticular) Different Degrees of Vascularization: Bones have a lot of vascular tissues. Depends on which tissue on how much vascular tissue you are likely to find.
cutaneous membrane
Dry membrane because it does not constantly secrete a mucous layer of fluid to the outside layer for the purpose of lubrication. Upper part of skin. Stratified Squamous connected to CT of the dermis. Epidermis and papillary layer make up cutaneous membrane. Facing the outside of the body.
What is the endothelium? The mesothelium?
Endothelium is the name for the simple squamous epithelium that lines blood vessels and lymphatic vessels. It is thin and extremely smooth. Mesothelium is the name for the simple squamous epithelium that helps form the serous membranes lining the ventral cavity.
connective tissue structural elements
Ground Substances (Make up extracellular mix) Water based fluid Ions Molecules Proteins Signaling molecules Sticky proteins Fibers (make up extracellular mix) Not alive Collagen (protein) Elastic Reticular (protein fiber)
Name some examples of tissues that have a high regenerative capacity. Name some examples of tissues that do not have a high regenerative capacity.
Highly regenerative tissues include: all epithelial tissues, loose areolar CT, dense irregular CT, blood and bone. Moderately regenerative tissues include dense regular CT, and smooth muscle tissue. Low regenerative capacity tissues include the cartilages and skeletal muscle tissues. Two tissues have almost no regenerative capacity (heart muscle cells and neurons).
What are the main differences between merocrine, holocrine, and apocrine methods of secretion? Are there any similarities between them? Provide an example for each of these types of secretion methods.
Merocrine glands secrete their products by exocytosis. These glands are not damaged by the secretion process. An example of a gland that uses this type of secretion is the eccrine sweat gland. Holocrine glands release their products by lysis of the entire cell, which kills the cell, so an active gland must be undergoing mitosis in order to continue secreting its product. An example of a gland that uses holocrine secretion is the sebaceous gland. Apocrine glands release their products by pinching off parts of the cell that contain vesicles of the product being secreted. The cell is damaged but does not die. It must repair itself to be able to secrete again. An example of a gland that uses this type of secretion is the mammary gland.
grandular secretion (merocrine, exocrine, apocrine)
Merocrine glands: secrete their products by exocytosis. Used by regular generic sweat glands (eccrine). (most common) Holocrine glands: the entire secretory cell ruptures, releasing secretions and dead cell fragments. Requires the destruction of the entire cell for the product to be secreted. Used by sebaceous glands. Apocrine Secretion: mixture between holocrine and merocrine. Used for some types of sweat glands and mammary glands. Kills part of the cell (Least common)
Why is scar tissue less effective than healthy tissue?
Scar tissue does not allow for stretching and recoil and is therefore much less flexible than other tissues. Its structure does not allow it to perform the same functions as the tissue it replaced.
describe the difference between simple and straified epithelial tissue q
Simple tissues contain a single layer of cells and stratified tissues contain multiple layers of cells.
epithelial characteristics
Specialized Contacts: Cell junctions that hold the cells closely together. Has tight junctions and desmosomes. Polarity: the top surface of the tissue is structurally different from the bottom surface of the tissue. The top surface: Apical >> Facing Lumen. Lumen= empty part of the hollow organ. Bottom Surface: Basal >> Basement membrane: layer of material that adheres the connective tissue to the epithelial tissue Avascular: no vascular tissue= no blood supply of their own. No blood vessels Supported by Connective Tissue: Connective tissue is vascular and is allowing oxygen and nutrients to diffuse into areas where there is none. Regenerative: they go through mitosis a lot and really fast and as much as possible. To repair damage.
Describe the difference between squamous, cuboidal, and columnar cells in terms of their overall shape and the shape of their nuclei.
Squamous cells are flattened and have a flat, oval nucleus. Cuboidal cells are roughly as wide as they are tall and have a round nucleus. Columnar cells are taller than they are wide and have an oval nucleus near the bottom.
What effect does an epithelial cell's shape have on its function? Provide 3 examples.
Squamous cells have smaller internal space and their thin size makes them perfect for diffusion and filtration processes since the distance the molecule has to travel is short. Cuboidal cells are as wide as they are tall, making them excellent for use as an absorption cell because they have a large apical surface, and perfect for building ducts because they are short but not too thin. Columnar cells are taller than they are wide, making them perfect for lining absorptive tubes and being interspersed with (right next to) goblet cells, which are also columnar, but secrete mucous.
describe the five characteristics of epithelial tissue
The five characteristics are: a. Specialized Contacts: cells in epithelial tissues are help together with desmosomes and/or tight junctions b. Polarity: Epithelial tissues have an apical and a basal surface. The apical surface faces the lumen or surface and the basal surface is attached to the basement membrane. c. Avascular: Epithelial tissues do not contain vascular tissue, but do have nerve input. d. Supported by Connective Tissue: Since the epithelial tissues are avascular they need to be closely associated with underlying connective tissues which provide nutrients and oxygen to them. e. Highly Regenerative: these tissues are able to perform mitosis to replace damaged cells.
If the basal layer of cells in a holocrine gland stopped going through mitosis, what might be the consequences?
The gland would lose the ability to secrete its product because there would be no pressure on the upper layers to cause them to rupture
. Describe the types of cells you might find in connective tissues.
The primary cell type in connective tissue proper is the fibroblast, which produces fibers. A mature fibroblast is called a fibrocyte. In cartilage the main cell is the chondroblast, which matures into a chondrocyte. In bone it is the osteoblast, which matures into an osteocyte. Other types of cells one might find in connective tissues are fat cells (store energy/nutrients), and immune system cells (white blood cells, mast cells, and macrophages).
Briefly describe the 3 steps of tissue repair.
The three steps of tissue repair are inflammation, organization, and regeneration. Inflammation allows fluid to move to an injured area, bringing immune system cells that fight infection and help with clot development. During the organization stage the blood clot is replaced by granulation tissue that brings new blood supply, and collagen fibers, which hold the two sides of the wound together, are produced. During the regeneration stage cells undergo mitosis to replace the damaged tissue, leaving a virtually undetectable area. When a wound is extensive or the damaged tissue amitotic, it is repaired only by using fibrous connective (scar) tissue, which is detectable even after healing has completed.
Describe the three types of fibers found in connective tissues.
The three types of fibers in CT are collagen, elastic, and reticular. Collagen forms long, thick strands that make the tissue strong and resistant to pulling forces. Elastic fibers are thinner than collagen and allow for a stretched tissue to recoil back to its initial pre‐stretch length. Reticular fibers have many branches that form interlocking networks that support the other structures in the tissue.
. Describe the extracellular matrix of connective tissues. What is it made of? Is it thick/dense or thin/loose? What determines if it is thick or thin? Does that allow for some specific functions? If so, provide examples of functions affected by the density of the extracellular matrix
The two major components of matrix are: ground substance and fibers. Ground substance includes interstitial fluid, proteoglycans, and glycosaminoglycans, as well as the ions and other molecules floating around in the fluid. Protein fibers come in three types: collagen, elastic, and reticular. If the extracellular matrix has a lot of fibers it tends to be thicker, stronger, and sometimes more elastic. If it contains few fibers it tends to be thin and allows for more fluid movement than a connective tissue with densely packed fibers between the cells. Some examples of connective tissues and their functions: loose areolar CT forms the soft packaging around organs, elastic cartilage is used to support the pinna of the ear, and dense elastic CT forms stretchy ligaments.
sereous membrane
Wet membrane. Covering the cavities and organs that are not exposed to the outside. Different from Mucous because Structure: they are much less likely to need a lot of layers. Made up of Simple Squamous connected to loose Areolar CT.
mucuous membrane
Wet membrane. Made of usually Stratified Squamous or simple columnar connected to loose areolar CT. Covering areas exposed to the outside environment. Cover the cavity to the external environment.
grandular classification
Where Product Released + Cell Number - Endocrine vs Exocrine - Unicellular vs Multicellular
Describe what consequences you would expect to have if your cutaneous membrane and your mucous membranes traded places.
Your cutaneous membrane is a dry membrane that covers the outside of your body. The mucous membranes are wet membranes that cover internal organs/cavities that are exposed to the external environment. If these two membranes traded places the outside of your body would be wet and the fluid would evaporate, causing the cells to increase their rate of secretion and therefore require more energy. Also, since your entire body surface would be subject to evaporative cooling you would have to expend more energy to maintain your normal body temperature. Meanwhile, the cutaneous membrane would now be covering the inner layers of your digestive system. This would lead to problems because moving food through your digestive tract requires lubrication and the cutaneous membrane would not be providing enough of that. The lack of lubrication would lead to damage to the organs in the abdominal cavity due to the friction created during movement and the lack of lubrication.
exocrine gland
affilaited with epithelial tissues secrete onto epithelial surface (skin or cavity) unicellular or multicellular have ducts
endocrine glands
affiliated with epithial tissue (a.k.a. ductless glands) - Hormones - Structurally diverse - Usually multicellular - Amino acids, peptides, glycoproteins, steroids - Secrete into ECF Blood Stream
gland
cell or cells that produce a product and secretes it outside of itself
Epithelial Tissue Function
covering and lining body cavities of the tissues covering and lining epithelium not every type of epithelial tissues performs every function protection absorption filtration excretion secretion sensory reception
-blast
creator cell
tubuluar vs aleveolar
epithelial Tubular glands have cells of a consistent shape that form a uniform tubular lumen, while alveolar glands have cells of a similarly uniform size within a large, sac-like lumen.
four basic types of tissues
epithelial, connective, nervous, muscle
tissues
groups of cells that are similar in structure and perform a related function
-cyte
mature cell
grandular epithelium
secretion is an active process used to describe the product