3) Integrating cells into tissues and organs

Question 1

What does coalesce mean?

Answer 1

Stick together

Question 2

When do cells first coalesce?

Answer 2

During embryogenesis when the inner mass (embryoblast) forms in the blastocyst

Question 3

What is a trophoblast and what does it develop into?

Answer 3

Trophoblast is the group of cells stuck together surrounding the embryoblast in a ring like structure which developed into the placenta

Question 4

Where do all cells of the body come from?

Answer 4

Epiblast which is fed by the yolk sac

Question 5

What allows cells to stick together?

Answer 5

1) Cell-cell adhesion molecules
2) Extra cellular matrix proteins (fibres)
3) Internal-external scaffolding
4) Close proximity (pressure effect)

Question 6

What is the extracellular matrix proteins?

Answer 6

The fibres/scaffolding outside of the cell

Question 7

Describe 5 characteristics of connective tissue layers

Answer 7

1) Direct attachment between two cells is rare
2) Extracellular matrix is plentiful
3) The matrix is rich in fibrous proteins (collagen!)
4) The matrix bears most of the mechanical stress, not the cells
5) Cells are sparsely distributed within it

Question 8

Describe 4 characteristics of epithelial tissue layers

Answer 8

1) Cells are attached together via cell-cell adhesions
2) Cells are tightly bound together into sheets called epithelia
3) Extracellular matrix is scant and consists mainly of basal laminar (a thin mat) which underlies the epithelium
4) Cell-cell adhesions bear most of the mechanical stress.
Therefore strong intracellular protein filaments cross the cytoplasm of each epithelial cell and attach to specialised junctions on the plasma membrane. Therefore the junction ties the cells surfaces of adjacent cells to each other or the basal lamina

Question 9

How does cell-cell adhesion molecules & extracellular matrix proteins hold cells together?

Answer 9

These hold all the tissues together in a scaffolding and keep the cells in place and in the right orientation.

Question 10

How does iternal-external scaffolding help keep cells together?

Answer 10

The internal-external scaffolding is connected to the extracellular matrix, holding the cells in their particular place.

Question 11

Define an organ

Answer 11

More than 1 tissue coming together