Intro to Histology

Question 1

What does epithelial tissue do?

Answer 1

serves as a lining or covering

Question 2

Main functions of epithelial tissue

Answer 2

Protection, transport, secretion/excretion, absorption

Question 3

Epithelial tissue characteristics

Answer 3

cell-cell junctions, functional polarity (top and bottom), basement membrane (basal ECM produced by epithelial cells)

Question 4

What are the types of cell-cell junctions?

Answer 4

tight junctions, anchoring junctions, desmosomes, hemi-desmosomes, and gap junctions

Question 5

Where are tight junctions on the cell and what is their function?

Answer 5

Just below the apical surface of the cell on the lateral border
they prevent anything from coming further down the cell surface into the tissue underneath

Question 6

Where are adhering junctions on the cell and what is their function?

Answer 6

Go around the entire perimeter of the cell wall
stick the cell wall to the adjacent cell wall to increase structural integrity and to communicate w the external environment

Question 7

Where are desmosomes and what is their function?

Answer 7

They are spots of adhesion that connect to other cell desmosomes via proteins called cadherins

Question 8

Where are hemidesmosomes and what is their function?

Answer 8

Attach the basement membrane (basal ECM) to the basal part of the cell via integrins

Question 9

What are gap junctions?

Answer 9

low resistance junctions that form a channel from one cell to the adjacent cells

Question 10

How are different types of epithelium classified?

Answer 10

of layers and the shape of the apical layer

Question 11

number of epithelial layers descriptors

Answer 11

Simple, pseudostratified, stratified

Question 12

different epithelial shape descriptors

Answer 12

Squamous, columnar, cuboidal, transitional

Question 13

How many layers are in simple epithelium and what kinds of shapes can it have?

Answer 13

one cell layer thick

squamous (nucleus squished & compressed), cuboidal (nucleus dead center), and columnar (nuclei closest to bottom)

Question 14

How many layers are in pseudostratified epithelium and what kinds of shapes can it have?

Answer 14

one cell layer thick

not all cells reach the surface, but they all touch the bottom

Question 15

How many layers are in stratified epithelium and what kinds of shapes can it have?

Answer 15

two or more layers
cuboidal and columnar are rare
stratified squamous can help anywhere there is a lot of wear and tear

Question 16

Integument main functions:

Answer 16

protection against antigens and utilized for immunity
homeostasis (prevents water loss)
sensation
metabolic functions

Question 17

Three layers of integument:

Answer 17

epidermis, dermis and subcutaneous layers

Question 18

Name the five layers of the epidermis

Answer 18

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum

Question 19

what are keratinocyes?

Answer 19

cells in epithelium that produce keratin

Question 20

what is keratin?

Answer 20

fibrous substance and protein that can withstand tensile stress

Question 21

What three cell types can be found in the Stratum Basale layer of the epidermis?

Answer 21

stem cells, melanocytes (produce melanin), and Merkel cells (sensory receptor cells)

Question 22

What are the main cells in the stratum spinosum and what is their function?

Answer 22

Langerhans cells aka prickle cells
First part of immune response; produced in bone marrow and migrate to skin (take antigen and remove it from epidermis)
They also have many desmosomes to weld to the adjacent membrane for constant abrasion and stabilization

Question 23

What’s going on in the stratum granulosum?

Answer 23

keratohyalin granules (keratin accumulation)
loss of nuclei
lamellar bodies (extrude waxy substance that waterproofs the skin)
cells connect to each other w/ tight junctions to prevent things going deeper/things from escaping

Question 24

Stratum lucidum

Answer 24

only in thick skin

transition zone from nuclei to none

Question 25

Stratum corneum

Answer 25

shredding keratin/dead skin cells

Question 26

What are the two layers of the dermis?

Answer 26

Papillary layer and Reticular layer

Question 27

What are the three things in the papillary layer of the dermis?

Answer 27

Dermal papillae (increase mechanical stability b/w the dermal and epidermal layers)
Meissener’s corpuscles (spiraled sensory organs)
Fibroblasts (wound healing)

Question 28

What is in the reticular layer of the dermis?

Answer 28

lymphatic vessels (where langherin cells deposit antigens
sebaceous glands

Question 29

What’s in the subcutaneous layer?

Answer 29

Loose CT (adipose tissue: fat tissue, insulation)
Pacinian corpuscles (Sensitive to deep pressure and vibration)
sweat glands (stem cells)

Question 30

What are free nerve endings and where are they located?

Answer 30

Lack coating of CT and are sensitive to pain and temperature

located in the epidermis

Question 31

What are Merkel’s cells and where are they located?

Answer 31

They are in the Stratum basale layer of the epidermis and are sensory receptor cells that are sensitive to touch (tactile)

Question 32

What are Meissner’s corpuscles and where are they located?

Answer 32

They are located in dermal papilla and they are tacticle

Question 33

What are Pacinian corpuscles and where are they located?

Answer 33

They are located in the Hypodermis and are sensitive to deep pressure and vibration

Question 34

What are Ruffini’s corpuscles and where are they located?

Answer 34

They are located in the Dermis and are sensitive to stretching