Porth's Essentials of Pathophysiology, 4e
20
Cell and Tissue Function
U N I T 1
Classification of TissueTypes
TABLE 1-1
TissueType
Location
Epithelial Tissue Covering and lining of body surfaces Simple epithelium Squamous
Lining of blood vessels, body cavities, alveoli of lungs Collecting tubules of kidney; covering of ovaries
Cuboidal Columnar
Lining of intestine and gallbladder
Stratified epithelium Squamous keratinized Squamous nonkeratinized
Skin
Mucous membranes of mouth, esophagus, and vagina
Cuboidal Columnar Transitional
Ducts of sweat glands
Large ducts of salivary and mammary glands; also found in conjunctiva
Bladder, ureters, renal pelvis Tracheal and respiratory passages
Pseudostratified
Glandular
Endocrine Exocrine
Pituitary gland, thyroid gland, adrenal and other glands Sweat glands and glands in gastrointestinal tract
Neuroepithelium
Olfactory mucosa, retina, tongue
Reproductive epithelium
Seminiferous tubules of testis; cortical portion of ovary
ConnectiveTissue Embryonic connective tissue Mesenchymal
Embryonic mesoderm
Mucous
Umbilical cord (Wharton jelly)
Adult connective tissue Loose or areolar
Subcutaneous areas Tendons and ligaments
Dense regular Dense irregular
Dermis of skin
Adipose Reticular
Fat pads, subcutaneous layers
Framework of lymphoid organs, bone marrow, liver
Specialized connective tissue Bone
Long bones, flat bones
Cartilage
Tracheal rings, external ear, articular surfaces Blood cells, myeloid tissue (bone marrow)
Hematopoietic
MuscleTissue Skeletal
Skeletal muscles Heart muscles
Cardiac Smooth
Gastrointestinal tract, blood vessels, bronchi, bladder, and others
NervousTissue Neurons Supporting cells
Central and peripheral neurons and nerve fibers
Glial and ependymal cells in central nervous system; Schwann and satellite cells in peripheral nervous system
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Epithelial Tissue Epithelial tissue forms sheets that cover the body’s outer surface, line the internal surfaces, and form glandular tis- sue. Underneath all types of epithelial tissue is a fibrous extracellular layer, called the basement membrane , which serves to attach the epithelial cells to adjacent connective tissue and may serve other functions, such as providing a barrier against cancer cell invasion and contributing to the filtration function of the glomerulus. The cells that make up epithelium have three general characteristics: (1) they have three distinct surfaces: a free surface or apical surface, a lateral surface, and a basal surface; (2) they are closely apposed and joined by cell-to-cell adhesion molecules, which form special- ized cell junctions; and (3) their basal surface is attached
tissues is called cell differentiation , a process that is controlled by mechanisms that switch genes on and off (see Chapter 4). All of the approximately 200 different cells of the body can be classified into the four basic or primary tis- sue types: epithelial, connective, muscle, and nervous (Table 1-1). These basic tissue types are often described by their embryonic origin. The embryo is essentially a three-layered tubular structure (Fig. 1-13). The outer layer of the tube is called the ectoderm ; the middle layer, the mesoderm ; and the inner layer, the endoderm . All of the mature tissue types originate from these three cel- lular layers. Epithelium has its origin in all three embry- onic layers, connective tissue and muscle develop mainly from the mesoderm, and nervous tissue develops from the ectoderm.
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