Lecture 5- Tissues Organs And Systems

Question 1

Define tissue

Answer 1

Group of cells adapted to a specific function

Question 2

Define organ

Answer 2

2+ tissues creating a structural unit that has a specific function(s)

Question 3

What are the 4 types of tissues

Answer 3

• Epithelial
• Nerve
• Connective
• Muscle

Question 4

Describe a connective tissue layer

Answer 4

-Lots of extracellular matrix (extra: contain fibroblasts for making fibres)
-Matrix contains fibrous polymers
- cells are spread out (sparsely distributed)
Rarely direct attachments to another cell

Question 5

Describe an epithelial tissue layer

Answer 5

• epithelia sheets- cells tightly bound together
• No extracellular matrix
• Basal lamina
• Cells attached to each other by adhesions

Question 6

What is the primary cell of connective tissue layers and what does it do?

Answer 6

Mesenchymal stem cell

• immature fibroblast
• able to interconvert
• produces extracellular fibres

Question 7

What are the 3 components of connective tissue?

Answer 7

• Cells- mainly mature fibroblasts
• Fibres- collagen, elastin etc
• Ground substance- glucosaminoglycans

Question 8

What are the functions of connective tissue?

Answer 8

1) binding and support
2) protection
3) insulation
4) storage of fuel and cells
5) transportation of substances
6) separation of tissues

Question 9

Where can epithelial tissue be found ?

Answer 9

All cavities and free surfaces of body

Question 10

Why do epithelial cells exhibit polarity?

Answer 10

They have apical (top), lateral (sides) and basal (bottom) surfaces which have different adaptations

Question 11

What cell adherence systems can be found on the lateral sides of epithelial cells?

Answer 11

• tight junctions
• Adherens junctions
• Desmosome
• Gap junctions
• Cell adhesion molecules

Question 12

What cell adherence systems can be found on the basal surface of epithelial cells?

Answer 12

• Hemi desmosome
• Focal Adhesions
• Integrins
• Proteoglycans
• Cell adhesion molecules

Question 13

What are tight junctions and where are they found?

Answer 13

Tight junctions are long cell to cell fusion points in a criss cross pattern that prevent the movement of larger molecules through the lumen

They are found at the very top of cells

Question 14

What are adhesions junctions and where are they found?

Answer 14

Adhesion junctions help stabilise junctions and act as a transport barrier. They are found in pairs 1/3rd down the luminal surface on lateral surface and come in pairs. They are also only found in epithelial and endothelial cells.

Question 15

What are desmosomes and where are they found?

Answer 15

Desmosomes provide mechanical strength and prevent tissue destruction. They can be found approx 1/2 way between basal and apical surfaces of cells. They are the strongest of all cell adhesions and are found in tissues that experience intense mechanical stress such as the bladder and uterus

Question 16

What are gap junctions and where are they found?

Answer 16

Gap junctions hold cells very close together to quickly communicate changes happening inside the cell (electrolyte and energy changes etc). They also allow the movement of small molecules between cells such as ions and sugars etc. They are found close to the basal surface of epithelial cells.
They are NOT found in motile cells such as spermatozoa.

Question 17

What are hemi-desmosomes and where are they found?

Answer 17

Hemi-desmosomes are found on basal surface and attach to the extracellular matrix.
They anchor epithelial cells to the basal lamina and prevent loss to external surface

Question 18

What are focal adhesions and where are they found?

Answer 18

Focal adhesions are found on the basal surface of epithelial cells and attaches the basal lamina.
They bind to fibronectin.

Question 19

Describe the role of integrins.

Answer 19

Intergrins hold tissue together.

Work as alpha-beta dimer (heterotetramer)

Question 20

What is the mucous membrane?

Answer 20

Lines all most hollow internal organs of the body