Tissues

Question 1

What is a tissue?

Answer 1

It is a group of cells of similar structure that perform a common function. Individual characteristics are put together in order to form a tissue that has similar functions

Question 2

What are the 4 types of tissue contained in our body?

Answer 2

Epithelial, connective, muscle, and nervous

Question 3

What is the main function of the linign epithelium?

Answer 3

To cover external body surfaces and internal body cavities

Question 4

Where do we find glandular epithelium?

Answer 4

Glands

Question 5

Cite three places where epithelial tissue is found:

Answer 5

• Respiratory passages
• Digestive tract
• Blodd vessels
• Serous cavities (pleura, pericardium, peritoneum)

Question 6

What are the main characteristics of epithelial tissue?

Answer 6

High cellularity (no extracellular space), polarity (apical/basal surfaces), specialized cell-cell contacts, avascularity (depends on underlying connective tissue for metabolic support), highly regenerative (regeneration), with high rates of mitotic division.

Question 7

Why is diffusion the main cell transport in epithelial tissue?

Answer 7

Because cells are kept so close together that there is no space available for blood vessels. Therefore, oxygen and other nutrients will be transported from cell to cell through diffusion.

Question 8

What are the different classifications of epithelial cells by cell layers?

Answer 8

Simple (one layer) and stratified (two or more layers)

Question 9

What are the different classifications of epithelia by cell shape?

Answer 9

Squamous (found in skin), cuboidal, columnar (enterocytes)

Question 10

What are the main characteristics of simple squamous epithelial tissue?

Answer 10

Single layer of flat, squashed cells. The thinest layer of cells, which is efficient because it’s easier for nutrients to move accross the the tissue (especially in places where protection is not important). Its main functions are diffusion and filtration and it can be found in the alveoli of the lungs, walls of the capillaries, endocardium, and endothelium

Question 11

What are the main characteristics of simple cuibodal epithelia?

Answer 11

Its main functions are secretion and absorption and are commonly found in kidney tubes and small glands

Question 12

What are the main characteristics of the simple columnar epithelia?

Answer 12

They are even more efficient in secretion and absorption; commonly found in the lining of most digestive tract (especially small intestine) and large glands

Question 13

How is it called the epithelia formed by a single layer of ciliated cells with different heigths, highly active in secreting and propelling mucus, commonly found in the lining of trachea and bronchi?

Answer 13

Ciliates Pseudostratified Columnar Epithelium

Question 14

If an epithelial tissue is described as ciliated, it means it does not move.

Answer 14

False. Ciliated cells are actively beating, moving the mucus away, helping to clean the airways from debris and microorganisms (that is why they are commonly found in the majority of the upper respiratory tract)

Question 15

The stratified squamos epithelia contains _________ cell layers and is responsible for ___________ from abrasion. There are two types: ___________ and ______________. Most commonly found in the mouth, esophagus, anus, and vagina.

Answer 15

Multiple, protection, keratinized, non-keratinized

Question 16

What is the shape of the basal cells found in non-keratinized stratified squamous epithelia? And the surface cells?

Question 17

What is the main characteristic of transitional epithelium?

Answer 17

The ability of switching between cell shapes without causing damage. Found in the lining of the urinary bladder

Question 18

How is the the glandular epithelium formed?

Answer 18

By the invagination of the tissue

Question 19

What is the main function of the glandular epithelia and how can they be divided?

Answer 19

To produce specialized secretions such as hormones, enzymes, saliva, and mucus. They can be divided in endocrine and exocrine

Question 20

How can we differentiate between endocrine and exocrine glands?

Answer 20

• Exocrine glands secrete products onto the surface of the epithelium. The multicellular exocrine glands hane a duct in order to secrete their products as they are located far away from the surface. The unicellular exocrine gland (also called goblet cell) produces mucus and does not have a duct.

Question 21

What are the two main parts of the exocrine glands and how are they classified?

Answer 21

Duct and secretory unit. They can be classified by the structure of the duct (either simple or compound) or by the structure of the secretory unit (tubular, alveloar, or tubuloalveolar)

Question 22

What are the main characteristics of the endocrine glands?

Answer 22

They do not have ducts as they secrete the products into the surrounding tissue fluid, which are then captured by the capillaries. These glands are mostly responsible for producing hormones which enter the bloodstream to reach the target organ.

Question 23

What are the main types of cell junctions?

Answer 23

Gap junctions (communication), tight junctions (impermeable barrier), desmosomes (keep cells together; intermediate filaments), and adhesive belt (keep cells together)

Question 24

Tight junctions (also called occluding junctions) are found in the _______ region and are formed by _____________ membrane proteins. It seals off the intercellular space and ______________. Responsible for maintaing the integrity of ___________ and apical membranes.

Answer 24

Apical, interlocking, prevents intercellular diffusion, lateral

Question 25

What are the main functions of the adhesive belt junctions?

Answer 25

Attaching one cell to another, reinforcing tight junctions, circling the cell as a belt and interacting with network of actin filaments

Question 26

Desmosomes interact with __________ and bind cells together. They ______________ mechanical shearing and tearing forces.

Answer 26

Intermediate filaments, resist

Question 27

Gap junctions are also called communicating junctions. What are their main functions?

Answer 27

Gap junctions are channels formed by transmembrane proteinss allowing direct intercellular communication. They offer free passage for small molecules such as ions, aminoacids, nucleotides, sugars and signaling molecules. Gap junctions are also present in cardiac and smooth muscles for sychronized contraction.

Question 28

Basement membrane is the name for which epithelia layer?

Answer 28

Basal lamina

Question 29

Basement membrane is a _______________ supporting layer that consists of _______________ secreted by ____________________. It is reinforced with ______________ and separates _________ from _______________ tissue. It works as a scaffolding for _____________ epithelium and selective filter between underlying CT and ________________.

Answer 29

non-cellular, proteins, epithelial cells, fine reticular fibers, epithelium, underlying connective tissue, regenerating, epithelium

Question 30

What is the main difference between microvilli and cilia?

Answer 30

Microvilli are finger-like extensions of apical plasma membrane, with the main function of maximizing surface are for absorption and diffusion, which increases cells efficiency (very common in the lining of small intestines). Cilia on the other hand are highly motile extensions of plasma membrane on apical surface. Their core is made out of microtubules and they move in coordinated waves. Their main function is to create a flow in one direction.