Ch. 4 Epithilial Tissue

Question 1

Tissue

Answer 1

A fabric or group of cells with similar structure and function.

Question 2

Four Primary Types of Tissue

Answer 2

Epithelium (covering)
Connective (support)
Muscle (movement)
Nervous (control)

Question 3

Epithelium Tissue (covering)

Answer 3

Lines skin surface.

Lines inside and outside of hollow organs.

Question 4

The importance of microscopic study of tissue

Answer 4

Histology- tissue; microscope
Biopsy- Take piece out
Autopsy- determine what was wrong.

Question 5

Definition of Epithelial Tissue and Gland

Answer 5

Sheet of cells that cover all free body surfaces (inside and out), forming an interface or boundary between two environments.

(Outside environment is coming in)
(Heart epi tissue inside no out)

Question 6

Functions of Epithelial Tissue and Glands

Answer 6

Protection= ex: digestive tract is exposed to outside world, lined lined with epithelial inside. Want monomers to cross though but not bacteria.

Absorption= Intake of molecules and substances,

Filtration= closely fitted cells can form a “strainer” with small holes.
(Kidney and capillaries, Artery carries blood away from heart and veins carries blood to the heart.)
(Oxygen is a gas exchange through diffusion in the blood stream; not absorption)

Secretion =release of molecules and substances.

Sensory reception = etc.

Question 7

Special Characteristics of Epithelial Tissue

Answer 7

Cellularity
Specialized contacts
Polarity 
Supported by Connective Tissue
Avascular but Innervated
Regeneration

Question 8

Special Characteristics of Epithelial Tissue

Cellularity

Answer 8

Cellularity is the min characteristic of epithelium tissue.
Boundary: Exhibit cellularity to help what can go in and out.
One cell touching one another in the matrix.

Question 9

Special Characteristics of Epithelial Tissue

Specialized Contacts

Answer 9

Between contacts

Question 10

Special Characteristics of Epithelial Tissue

Polarity

Answer 10

(I free surface ; 1 bound surface)

Apical surface: (Gnot) Free surface: dead cells, keratin filled. Waterproof

Basal surface: bound surface connective tissue. Gets more O2 supply

Question 11

Special Characteristics of Epithelial Tissue

Answer 11

Supported by connective tissue; basement.

Question 12

Special Characteristics of Epithelial Tissue

Avascular but Innervated

Answer 12

Has neurons in it. Without blood vessels, none in the epithelium tissue, need ATP/ O2 gets oxygen from blood vessels in connective tissue to diffuse from the connective tissue to basal surface to epithelium.

Question 13

Special Characteristics

Regeneration:

Answer 13

Mitosis: replace stomach lining every 3 days, replace skin cells every 6 days

Question 14

Epithelial has the most cancers

Answer 14

Lung, skin, liver, kidney, stomach, etc.

Epithelial has higher risk of cancer because it goes through division a lot.

Question 15

Special structural Features

Answer 15

Apical surface 
      -Microvilli
      -Cilia 
Lateral Cell Junctions 
      -Desmosomes 
      -Tight Junctions
      -Gap Junctions 
Basal Surface
      -Basal Lamina
      -Basement Membrane

Question 16

Microvilli

Answer 16

Apical: Intestine
Fingerlike extensions of epithelial cells lining one parts of the digestive tract or kidney. Surface area is increased. Increasing absorption and secretion. May also create adhesion points for secreted mucus.

Question 17

Cilia

Answer 17

In the trachea
Microtubules project form cell membrane as hairs that move uniformly in one direction (wave like). They can move substances along the surface of a sheet of epithelial cells.

Nicotine decreases ciliary action.

Question 18

Desmosomes

Answer 18

Connection type;
Can't rip skin of (stuck)
Anchoring junctions (linking proteins) between cells that prevent cells subjected to mechanical stress (such as skin cells)from being pulled apart

Confers strength.

Sew cells together (Velcro) strength From mechanical stress
(Skin cells)

Question 19

Tight Junction

Answer 19

Rivers that securely fuse adjacent plasma membranes together into leak proof sheets; extracellular space.

Prevent substances, chemicals, bacteria, etc. from passing between cells. (Ziploc seams to keep bacteria from going in between the cells.)

Question 20

Gap Junctions

Answer 20

Intercilialated discs highly concentrated in Gap Junction.
Allow substances to leak between cells

Intracellular space
Channel between cells formed by connexons

• contractions Ion concentrations do that wave cell. Heart blood pumping in the heart muscle.

Question 21

Basal Lamina

Answer 21

Non cellular, adhesive sheet of glycoproteins secreted by epithelial cells toward the neighboring connective tissue layer.

Functions: Selective filter, scaffold to which epithelial cells can migrate or grow upon.

Combines with fibers from CT layer to form basement membrane.

Basement Membrane: Located just deep to basal Lamina. Reinforces epithelial sheet and defines epithelial boundary.

Question 22

Classification of Epithelium

Answer 22

Two names followed by - epithelium
First name: # of layers
Simple: one layer

Stratified: more than one layer

Pseudostratified: Looks like more than one layer but isn’t. (Found in cilia-trachea) Touches the Apical and basal surface.

Second Name: Shape of cells on Apical surface
Squamous: flat, scale, or plate like. (Nucleus is flat and disc like)

Cuboidal: Cube shaped or box like (nucleus is large and round, spherical. As tall as the are wide.

Columnar: Tall and Column shaped. (Nucleus is oval and elongated, located in basal. 1/3 Taller than they are wide. (Epithelial doesn’t have Apical columnar)

Question 23

Glandular Epithelium

Answer 23

Glands
Secretory pathway
Endocrine glands
Exocrine glands

Question 24

Glands

Answer 24

One or more epithelial cells organized to make and secrete (export) a particular product (often an aqueous fluid that contains proteins)

Question 25

Secretory Pathway

Answer 25

Secrete by Exocytosis

RER -> Glogi -> Vesicles -> Exocytosis

Question 26

Endocrine Glands

Answer 26

Ductless (secretion into blood stream)
Hormones, no ducts: protein based secreted by blood stream substance secreted in body to target elsewhere in the body

Hormones get into blood by endocrine gland.

• Secretions are chemical messenger molecules called hormones.
• Each messenger (hormone) is a regulatory chemical manufactured to react with a specific “target” organs in some specific way.
• ex: the pancreas has an endocrine function where some of its glandular cells produce the hormone insulin which affects the energy pathways used by many organs of the body.

Question 27

Exocrine Glands

Answer 27

Exo: exit does not release hormones, Goes through Ducts/ pores of some surface, not blood vessels

Example, saliva in mouth, pancreas (not always outside the body) release pancreatic juices pores on inside of intestine to help hydrolysis takes place to digest.

Question 28

Exocrine Glands: Unicellular

Answer 28

Single goblet cell secretes a protein called Mucin

Mucin + H2O -> slimy, viscous mucus

One cell makes mucus on the surface of intestine and trachea.

Question 29

Exocrine Glands: Multicellular

Answer 29

Can vary in shape. All have ducts/ pores/ release on the surface.

Secretory unit + duct
Ex: sweat and oil glands, salivary glands, liver, pancreas (has both endocrine and exocrine) etc.