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by: Manny-verda Sindjui

Epithelial BIO 221

Manny-verda Sindjui
GPA 3.44

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simple and stratified
Human Anatomy Physiology 1
Stella Evans
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This 4 page Bundle was uploaded by Manny-verda Sindjui on Friday February 19, 2016. The Bundle belongs to BIO 221 at Towson University taught by Stella Evans in Spring 2016. Since its upload, it has received 15 views.

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Date Created: 02/19/16
1 BIOL 221 Epithelium and Glands Histology – Study of tissue What is a tissue? Groups of specialized cells and cell products that work together to perform specific  functions Tissue classes:   Epithelial­ covers exposed surfaces, line internal passageways and chambers, and forms glands   Connective­fills internal spaces, provides structural support for other tissues, transports  materials within the body and stores energy   Muscle­ specialized for contraction and includes the skeletal muscles of the body, the muscle of  the heart, and the muscular walls of hollow organs   Nervous­ carries information from one part of the body to another in the form of electrical  impulses Epithelial Tissue: lines tract and cavities o Functions o Protection  o Produce secretions  o Absorption, excretion and filtration  o Sensation   Characteristics of epithelial tissue o Polarity: (Fig 4­1_  apical surface   lateral surface   basal surface  basal lamina  o attachment: (basal lamina) o avascularity: (avascular tissue) o regeneration: replaces damage spaces. (Except nerve cells) o cellularity: Bound closely)  Cell junctions (Fig 4­2)  Tight junction­ Locks 2 cells together. Act as protection. Prevents movement of  substance   Gap junction­ in between 2 cells. Allows free diffusion between 2 cells   Button desmosome­ ties adjacent cells together. Holds heart cells together so  it wont pull apart when contracting  Hemidesmosome­ holds in place not allowing cell to move Classification of epithelial cells (Table 4­1)  Simple­ one/ single layer  Stratified­ Multiple layer Simple squamous  (Fig 4­3)           Function: reduces friction; controls vessel permeability; performs absorption and secretion  2           Location: Mesothelia, lining pleural, pericardial, and peritoneal cavities; endothelia, lining heart and blood vessels; portions of kidney tubules (thin secretions of nephron  loops); alveoli of lungs Stratified squamous (Fig 4­3) Function: Provides physical protection against abrasion, pathogens, and chemical attack Location: Surface of skin, lining of mouth, throat, esophagus, rectum, anus, and vagina Simple cuboidal (Fig 4­4) Function: Limited protection, secretion, absorption Location: Glands; ducts; portions of kidney tubules; thyroid Stratified cuboidal (Fig 4­4) Function: Protection, secretion, absorption Location: Linin of some ducts(rare) Simple columnar (Fig 4­5) Function: Protection, secretion, absorption Location: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys Stratified columnar Function: Protection  Location: Small areas of the pharynx, epiglottis, anus, mammary glands, salivary gland ducts,  and urethra Pseudostratified columnar  (Fig 4­5) Function: Protection, secretion, move mucus with cilia Location: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract Transitional (Fig 4­4) Function: Permits expansion and recoil after stretching Location: Urinary bladder; renal pelvis; ureters Glandular epithelium  endocrine glands – (endo – inside) ductless glands. Secretion enters pathway. Brings substance  in pathway  exocrine glands – (exo – outside) connected by ducts. Secretion exit pathway. Release substance out of pathway Exocrine glands (Fig 4­6) o Gland structure (Fig 4­7)  unicellular glands: single­celled  multicellular glands: all other exocrine glands   branched or unbranched o simple gland­ single duct, don’t divide going to gland cells o compound gland­ divides one or two more times on its way to gland  cells  secretory portion: o tubular: glands whose glandular cells form tubes (straight or coiled) 3 o acinar or alveolar: forms blind pockets o Modes of secretion (Fig 4­6)  merocrine glands: Released from secretory vesicles by exocytosis  apocrine glands : Involves the loss of cytoplasm as well as secretory product.  Portion of cytoplasm becomes packed with secretory vesicles and is then shed  holocrine glands: Destroys gland cells. Entire cell becomes packed with secretory  vesicles and then bursts, releasing secretion, but killing cells o Types of secretions  Serous­ secrete watery solution that contains enzymes  Mucous­ secrete mucins that hydrate to form mucus    mixed exocrine­ contains more than one type of gland. May produce two different  exocrine secretions: serous and mucus  Review questions from your book: 1. Distinguish between simple and stratified epithelia, and explain why pseudostratified columnar  epithelium belongs in the former category. Simple is one layer Stratified is multiple layer Pseudostratified­ a single layer but looks like a double layer. False double layer 2. Explain how to distinguish a stratified squamous epithelium from a transitional epithelium. 3. What function do keratinized and nonkeratinized stratified squamous epithelia have in common? What is the structural difference between the two? How is this structure difference related to a functional difference  between them? Both protection Keratinized­ cilia: helps moves mucus or anything they are protecting Nonkeratinized­ no cilia 4. How do the epithelia of the esophagus and stomach differ? How does this relate to their respective  functions? Stomach is a single layer­ simple columnar, secrets and absorbs nutrient esophagus has multiple layer­ stratified squamous. Protects from abrasion, pathogen, chemical  attacks 5. Compare the structure of tight junctions and gap junctions. Relate their structural differences to their  functional differences. Tight junction fuse together by membrane Gap junction separate. Cell hold together by protein membrane that forms whole cylinders  6. Distinguish between a simple gland and a compound gland, and give an example of each. What about a  tubular gland and an acinar gland? Tubular forms tubes Acinar forms pockets 4 7. Contrast the merocrine and holocrine methods of secretion, and name a gland product produced by each  method. Merocrine­ releases secretory by exostyosis Holocrine­ Destroys gland cells. Entire cell becomes packed with secretory vesicles and then  bursts, releasing secretion, but killing cells 8. Describe the differences between a mucous and a serous membrane. Serous­ secrete watery solution that contains enzymes Mucous­ secrete mucins that hydrate to form mucus   9. The epithelium of the respiratory tract is mostly of the pseudostratified columnar ciliated type, but in the  alveoli – the tiny air sacs where oxygen and carbon dioxide are exchanged between the blood and inhaled air  – the epithelium is simple squamous. Explain the functional significance of this histological difference. That is,  why don’t the alveoli have the same kind of epithelium as the rest of the respiratory tract? They both 


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