Epithelial Tissue I and II

Question 1

what is epithelial function

Answer 1

• protection
• transcellular transport
• secretion
• absorption
• sensory detection

Question 2

describe what epithelial cells are made of/their functions

Answer 2

• are ALWAYS avascular –> don’t have blood vessels
• >can’t get too thick as it has to access nearby vessels

Question 3

what do epithelial cells exhibit?

Answer 3

POLARITY

attached basally to a basement membrane
apical side faces into lumen/outside world

lateral domain borders neighboring cells

Question 4

basal domain

Answer 4

borders on basement membrane, related to underlying connective tissue

Question 5

name an apical specialization

Answer 5

microvilli

Question 6

what do microvilli do?

Answer 6

they extend into the lumen to increase surface area for absorption

Question 7

where are microvilli found?

Answer 7

places like the intestines or the kidney tubules

Question 8

what is the make up of microvilli?

Answer 8

they have an actin core

actin is STIFF

Question 9

what is the glycocalyx and what does it do?

Answer 9

is: carb chains linked to membrane proteins or lipids
does: associated with microvilli and aids absorption

Question 10

what are cilia?

Answer 10

mobile, hair like structures that extend from dark basal bodies

they always move and tend to do so in the same direction

Question 11

what core do cilia have?

Answer 11

microtubules

Question 12

how do the microtubules change within a cilia?

Answer 12

basal bodies: near the base, 9 triplet formation

cilium proper: near the top, 9 + 2 arrangement

Question 13

what are the lateral domain functions

Answer 13

1) form a selective barrier
2) adherence
3) communication

Question 14

what are lateral interdigitations and what do they do?

Answer 14

they are infoldings between cells

are prominent in cells engaged in fluid transport —> ex: intestines

they increase lateral surface area

Question 15

what is the junctional complex made of?

Answer 15

zonula occludens (tight junction) —-> more apical

zonula adherens (intermediate junction)

macula adherens (desmosome) —-> still apical but less so

Question 16

what is the zonula occludens function?

Answer 16

form a protective barrier between epithelial cells

separates the luminal space from the intercellular space and the CT compartment

is the first line of defense

essentially the police

has intermittent contact and separations of lateral plasma membranes of adjacent epithelial cells

Question 17

what is the zonula adherens function

Answer 17

cell to cell adhesion as cells do not contact each other

Question 18

how do cells connect?

Answer 18

integral membrane proteins

the cells themselves do not touch - are instead connected by a bridge essentially

Question 19

what is the macula adherens function?

Answer 19

cell to cell adhesion

Question 20

what are macula adherens made up of?

Answer 20

attachment plaques (gives stability), intermediate filaments, linking proteins

Question 21

what are gap junctions?

Answer 21

specialized lateral domain

Question 22

what do gap junctions do?

Answer 22

exchange or signaling between adjacent cells

found in tissues that accomplish coordinated functions —> ex: cardiac muscle, neurons

Question 23

what is the structure of a gap junction?

Answer 23

one cell membrane that has connexons that can be open or closed

connexons connect to other connexons to pass things between cells

Question 24

what are lateral domains made up of?

Answer 24

the junctional complex + gap junctions

Question 25

name a basal domain specialization

Answer 25

cell to ECM adhesion

Question 26

what are hemidesmosomes and what are they associated with?

Answer 26

1/2 a desmosome and help the epithelial cell attach to the basal lamina are associated with attachment plaques and intermediate filaments

Question 27

describe focal adhesions/what they are associated with

Answer 27

associated with actin filaments important for mechanoreception and proprioception

Question 28

how are covering epithelium classified?

Answer 28

by the number of cell layers (either simple or stratified) shape of cell closest to lumen/outside world

Question 29

name the types of simple classifications

Answer 29

1) squamous - flat 2) cubodial - square/cubes 3) columnar - taller

Question 30

name the 2 types of stratified epithelium and how they are specifically named

Answer 30

non-keratinized (very tough) and keratinized (toughest) named for shape of cells in the apical layer

Question 31

what is the pseudostratified columnar epithelium?

Answer 31

SIMPLE EPITHELIUM 1 cell layer thick all cells "touch" the basement membrane but don't all reach the lumen

Question 32

what is the transitional epithelium?

Answer 32

STRATIFIED unique rounded surface cells, distensible property (=urothelium) ONLY FOUND IN URINARY BLADDER round = no urine, distended = lots of urine

Question 33

name the 2 types of gland tissue and what they do

Answer 33

1) parenchyma: epithelial cells ---\> working cells 2) stroma: CT ---\> supporting tissue

Question 34

what do endocrine glands do

Answer 34

secrete hormones into blood or lymphatic vessels located in CT

Question 35

what do exocrine glands do

Answer 35

secrete into ducts

Question 36

describe endocrine glands

Answer 36

-small secretory granules located in basal cytoplasm are polarized **TOWARD** the basement membrane ---\> **REVERSE POLARITY** secretion can be constitutive or regulated

Question 37

how are exocrine glands classified?

Answer 37

1. structure (branching of ducts): simple or compound 1. can also be under shape of secretory unit: tubular, acinar (berry), etc 2. type of secretion: serous (watery) or mucous

Question 38

describe serous-secreting compound glands

Answer 38

* pyramidal-shaped cells * basally located, round nuclei * basophilic basal cytoplasm * apical cytoplasm: lighter stained, secretory granules

Question 39

what organelle is abundant in the basal portion of the cell?

Answer 39

rER

Question 40

where is the golgi complex located?

Answer 40

supranuclear

Question 41

where are the secretory granules located?

Answer 41

apical cytoplasm (toward lumen)

Question 42

describe mucous-secreting glands

Answer 42

- goblet cells: not in a gland - secretes mucins (hydrophilic glycoproteins) TEM: rER in basal portion of cell, supranuclear golgi complex, secretory granules in apical region STAINING: pale apical cytoplasm, darkly stained nuclei basally