Epithelia

Question 1

What are the roles of epithelial tissue?

Characteristics?

What is the think extracellular, felt-like sheet epithelial cells rest on?

Epithelium that is involved in secretion is arranged as:

Answer 1

• roles: physical protection, permeability, secretion, and sensation
• characteristics: cellularity, polarity, attachment (to basement membrane), avascular (get nutrients through diffusion), innervation, and regeneration
• rests on: basement membrane
• secretory glands

Question 2

Two parts to this card:

Part 1: cells show polarity; organelles and proteins are ________ distributed

Part 2: picture:

Answer 2

• unevenly
• (top to bottom of picture): apical (free) surface, lateral surface, and basal surface

Question 3

• type of intercellular junction
• impermeable, allows cells to function as a barrier (especially if high number of these are present)
• encircle cells near most apical surface
• proteins: occludins, claudins
• similar to a draw string bag, the higher number of these junctions present, the lower the permeability will be

Answer 3

tight/occluding junctions

Question 4

• type of intercellular junction
• fluid-filled channels that connect opposed cells
• proteins: connexin aggregates

Answer 4

gap junction (communicating junction)

Question 5

• type of intercellular junction
• multiple types: adherens, desmosome, hemidesmosomes
• adherens: lateral adhesions involving cadherin:actin interations
• desmosome: lateral adhesions involving cadherins:intermediate filament interactions
• hemidesmosomes: basal adhesions involving intergrins:intermediate filament interactions

Answer 5

anchoring junctions

Question 6

• clinical relevance of intercellular junctions
• bacteria that cause food poisoning target _____ _______ in the intestine which impairs the junction and causes loss of tissue fuid into intestinal lumen
• H. pylori causes gastric ulcers by binding to _____ _______ in the stomach and increasing permeability, loss of gastric contents (acid) causes the ulcers

Answer 6

tight junctions

Question 7

• clinical relevance of intercellular junctions
• autoimmune disease pemphigus vulgaris causes abnormal _________ function which reduces cell-cell adhesion and causes blisters in the oral mucosa

Answer 7

desmosomes

Question 8

• specialized sheet of extracellular material that is located adjacent to basal domain
• selective barrier between tissues permits diffusion of nutrients
• on tissue stains, it can help identify epithelial tissue boundary

Answer 8

basement membrane

Question 9

• type of apical specialization
• cytoplasmic processes containing an actin core and covered in plasma membrane
• specialized for absorption
• number/shape correlate to the cell’s absorptive capacity
• celiac disease: loss of ______ on absorptive cells in SI

Answer 9

microvilli

Question 10

• type of apical specialization
• microvilli of unusual length, long and less mobile than cilia
• have an actin core and increase surface area for absorption/secretion
• restricted locations: epididymis (absorption/secretion) and hair cells of inner ear (structural, bend to initiate hearing)

Answer 10

sterocilia

Question 11

• type of apical specialization
• long, highly motile stuctures containing internal arrays of microtubules (up to 10mm long, 300+ may be present)
• motile: beat in a wave-like fashion to propel substances across the tissue
• primary: immotile, function as chemosensors, osmosensors, and mechanosensors
• nodal: embryonic, have role in L/R axis determination

(critical in airways)

Answer 11

cilia

Question 12

How do you classify tissue type?

Answer 12

1. Determine the amount of layers present: 1 layer = simple, 2+ layers = stratified
2. Determine the shape of the cells on the apical surface: squamous cells are flat, cuboidal cells are cube shaped, and columnar cells are column shaped

Question 13

• tissue type
• location: lining of blood and lymphatic vessels (endothelium), lining of serous membranes (mesothelium), lining alveoli in lungs, loop of Henle in kidneys, various ducts
• function: exchange, barrier, and lubrication

Answer 13

simple squamous

Question 14

• tissue type
• location: kidney tubules, glands and associated ducts, terminal bronchioles, covering the ovaries
• function: absorption, barrier, secretion

Answer 14

simple cuboidal

Question 15

• tissue type
• location: auditory tubes, uterus, oviducts, stomach, SI/LI, gallbladder
• function: absorption and secretion
• nucleus can be round/egg shaped, and the cells can be ciliated

Answer 15

simple columnar

Question 16

• tissue type
• location: lining of nasal cavity, pharynx, trachea, bronchi
• function: absorption/secretion, debris and particulate movement
• restricted to airways, mucus secretion

Answer 16

pseudostratified columnar ciliated

Question 17

• tissue type
• pseudostratified, transitional epithelium
• location: urinary bladder, ureters, urethra
• function: barrier, distensible property, keep out toxic waste

Answer 17

urothelium

(top of cartoon pic is bladder empty, bottom of cartoon pic is bladder full)

Question 18

• tissue type
• location: oral cavity, portions of the pharynx, esophagus, anus, vagina, urethra, cornea
• function: barrier, protection

(areas w/ constant/frequent abrasion)

Answer 18

nonkeratinized stratified squamous

Question 19

• tissue type
• location: epidermis of the skin
• function: barrier, protection
• kertain filaments on outermost surface gives skin a bit of water proofing

Answer 19

keratinized stratified squamous

Question 20

• tissue type
• location: sweat glands/ducts, ovarian follicles, salivary gland ducts
• function: barrier, passageway
• need to be able to release secretory product w/o losing it all completely

Answer 20

stratified cuboidal/columnar

Question 21

Epithelial decision tree (study guide):

Answer 21

Question 22

• type of membrane
• epithelial tissue that secretes mucus
• lines many body cavities and tubular organs, including the gut and respiratory passages

Answer 22

mucous membrane

Question 23

• type of membrane
• epithelial tissue that lines internal body cavities
• forms a smooth, transparent, two-layered membrane
• lubricated by fluid derived from serum to reduce friction
• includes peritoneum, pericardium, and pleura
• mesothelium: simple squamous epithelium that comprises part of a _____ _______

Answer 23

serous membrane

Question 24

• Epithelial cells may produce & secrete a product as individual cells or as specialized organs, _____
• Glands are classified as ______ or _______ according to how their products are released
• Classified by arrangement & shape of secretory cells & ductal elements
• Signals released via _______ or _______ signaling

Answer 24

• glands
• exocrine, endocrine
• paracrine, autocrine

Question 25

- type of gland - single, secretory cells distributed among non-secretory cells - **globlet cell**: mucus-secreting cell lining the intestines and respiratory tract

Answer 25

unicellular glands

Question 26

- type of gland - **multicellular glands** comprised of secretory cells grouped as an **acinus** (means grape) - product is secreted into a system of **ducts** for release - **paranchyma (secretory cells)**: functional tissue of an organ (not the CT and other supporting tissues) - **stroma**: connective tissue support of secretory units; **septa** partition the gland into separate lobules; may enclose entire gland as a **capsule**

Answer 26

exocrine glands (secretions produced in secretory portions (acinus) and released in conducting portions (duct))

Question 27

- type of exocrine gland - secretion is delivered in membrane-bound vesicles to apical surface and undergo exocytosis

Answer 27

merocrine

Question 28

- type of exocrine gland - secretion accumulates within a cell leading to apoptosis - secretion and cell debris are released

Answer 28

holocrine

Question 29

- type of gland - release of the apical portion of the cell, surrounded by cytoplasm within a plasma membrane - example: mammilary glands

Answer 29

apocrine

Question 30

Name these glands:

Answer 30

(from left to right) - simple tubular - simple coiled tubular - simple branched tubular - simple acinar - simple branched acinar

Question 31

Name these glands:

Answer 31

(from left to right) - compound tubular - compound acinar (salivary gland) - compound tubuloacinar (salivary gland)

Question 32

Tissue type table: (study guide)

Answer 32