Epithelial Tissues And Exocrine Glands Flashcards
(32 cards)
What is a mucous membrane?
They line internal tubes which open to the exterior. They bear mucus secreting cells to some degree.
What is a serous membrane?
Thin, two part membranes which line certain closed body cavities. The secrete a lubricating fluid which promotes friction free movement.
Give some examples of where you will find mucous membranes:
Alimentary tract, urinary tract, respiratory tract
Give some examples of where you will find serous membranes:
The viscera, peritoneum, pleural sacs, pericardial sac.
Describe a mucous membrane histologically:
An epithelium and adjacent layer of connective tissue (lamina propria).
A layer of smooth muscle also in the alimentary tract.
Describe a serous membrane histologically:
Simple squamous epithelium which secretes a lubricating fluid and a thin layer of connective tissue.
Define epithelia:
Sheets of contiguous cells, of varied embryonic origin, that cover the external surface of the body and line internal surfaces.
Describe simple epithelia:
One cell layer thick
Describe cuboidal epithelia:
Appear square in section perpendicular to the basement membrane
Describe squamous epithelia:
Flattened, irregularly shaped cells
Describe columnar epithelia:
Taller than cuboidal, appear columnar at right angles to the basement membrane.
Describe pseudostratified epithelia:
Columnar epithelia with nuclei disposed at different levels.
Describe transitional epithelia:
Stratifies epithelium that is specialised to stretch. Appears 4-5 cells when relaxed, 2-3 when stretched.
Describe stratified epithelia:
More than one cell layer thick
Describe the epidermis:
Stratifies squamous keratinised epithelium made if keratinocytes and their products.
What are the four layers of the epidermis?
Stratum corneum (horny layer)
Stratum granulosum (granular layer)
Stratum spinosum (prickle cell layer)
Stratum basale (basal layer)
What is the basal layer/surface?
The interface between epithelia and underlying supporting tissues. Marked by the basement membrane.
What makes up the granular layer?
Keratinocyte granules
Other fibrous proteins
Enzymes which degrade the phospholipid bilayer
Cross linking proteins (fillagrin)
What is the horny layer made of?
Flattened corneocytes
What makes up the prickle cell layer?
Daughter keratinocytes. Terminal differentiation begins here and keratinocytes lose their ability to divide.
How long does it take a keratinocyte to move from the basal layer to the stratum corneum?
28-40 days.
What are melanocytes?
Dendritic cells of neural crest origin
Found at basal layers
Produce melanocytes
What are langerhans cells?
Dendritic cells of bone marrow origin
Scattered throughout the prickle cell layer
Present antigens to T lymphocytes
What is a gland?
An epithelial cell or collection of cells specialised for secretion
