Interactions Between Cells and the Extracellular Environment Part 1

Question 1

What is extracellular matrix composed of?

Answer 1

Consists of the protein fibers collagen and elastin, as well as a gel-like ground substance.

Question 2

The interstitial fluid composes how much of extracellular water? and where is it found?

Answer 2

Extracellular H2O= 33%, 80% of that is interstitial fluid found in the gel like ground substance of extracellular matrix.

Question 3

What is the gel composed of in the ground substance?

Answer 3

Glycoproteins (numerous side chains of sugars) and proteoglycans. These are composed primarily of polysaccharides and have a high content of bound water molecules.

Question 4

Describe how collagen IV helps provide structural strength in the body.

Answer 4

Collagen IV contributes to the basal lamina underlying epithelial membranes. By forming chemical bonds between the carbs on the outside surface of the plasma membrane of the epithelial cells, and the glycoproteins and proteoglycans of the matrix in the connective tissues, the basal lamina helps to wed the epithelium to its underlying connective tissues.

Question 5

What are Integrins?

Answer 5

Integrins are a class of glycoproteins that extend from the cytoskeleton within a cell, through the plasma membrane, and into the extracellular matrix.

Question 6

Name the six things Integrins can do.

Answer 6

1- Serve as adhesion molecules between cells and the extracellular matrix.
2- Serve to relay signals between the intracellular and extracellular environment, thereby integrating the two compartments.
3- Impart a polarity to the cell so that one side is distinguished structurally and functionally from another (apical from basal for ex.)
4- Affect cell adhesion in a tissue and the ability of certain cells to be motile.
5- Affect the ability of cells to proliferate in their tissues.
6- Extracellular matrix proteins and proteoglycans also bind to secreted regulatory chemicals, particularly various growth factors, and help to deliver these to integrins and receptor proteins at the cell surface.

Question 7

Brush Border is another name for what?

Answer 7

Microvilli

Question 8

What is an Osmotically Active Solute?

Answer 8

A solute that cannot freely pass across a membrane and therefore promotes the osmotic movement of water

Question 9

Osmotic Pressure

Answer 9

The pressure required to stop osmosis. (force to stop the movement of H20)
Because osmotic pressure is a measure of the force required to stop osmosis, it indicates how strongly a solution draws water by osmosis.

Question 10

1 Molar Solution

Answer 10

A 1 molar solution is 1 mole of substance and then an unspecified amount of water is added until you get 1 L.

Question 11

1 Molal Solution

Answer 11

1 Mole of substance plus 1 L of water. ( 1L= 1 Kg)

Question 12

What depends on the ratio of solute to solvent and not on the chemical nature of the solute molecules?

Answer 12

Osmotic Pressure

Question 13

Osmolality of Plasma

Answer 13

.3 osmolal (Osm) or 300 miliosmolal (mOsm)

Question 14

One mole of solute per liter depresses the freezing point of water by how much?

Answer 14

-(depresses) 1.86 degrees C

Question 15

The freezing point depression is a measure of the what?

Answer 15

Osmolality.
The freezing point of a solution, like its osmotic pressure, is affected by the total concentration of the solution and not by the chemical nature of the solute.

Question 16

Plasma freezes at about what temperature?

Answer 16

-.56 degree C

Question 17

What does it mean when something is isosmotic to plasma?

Answer 17

It means they have the same osmolality as plasma.

Question 18

Tonicity

Answer 18

term used to describe the effect of a solution on the osmotic movement of water.

Question 19

Isotonic

Answer 19

No net movement, just random diffusion.

Question 20

Hypo-osmotic to Plasma

Answer 20

Solutions that have a lower total concentration of solutes than that of plasma, and therefore also have a lower osmotic pressure.

Question 21

Hypotonic Solutions to Plasma

Answer 21

Solute is osmotically active, this means water will move from the extracellular environment into the cell. The cell may get to the point where it undergoes hemolysis, gains too much water and bursts (lyses).

Question 22

Hypertonic Solutions to Plasma

Answer 22

The solution contains a higher concentration of osmotically active solutes than the cell. They are also hyper-osmotic to plasma. This causes the water from the cell to move to the extracellular environment causes the cell to crenate (shrink).

Question 23

Another name for Vasopressin

Answer 23

Antidiuretic Hormone

Question 24

If you were dehydrated what would your blood volume be like?

Answer 24

You would have a lower total blood volume

Question 25

If you had a normal blood volume but ate a lot of salt what would your body need to do to restore the plasma osmolal?

Answer 25

You would be able to restore the blood osmolal by increasing amount of water uptake and increasing the overall total blood volume

Question 26

Two consequences of osmoreceptors crenating?

Answer 26

1- Person becomes thirsty and will drink if water is available.
2- Osmoreceptors will increase their production of nerve impulses along a track of axons that terminate in the posterior pituitary. Increase in stimulus leads to the posterior pituitary releasing antidiuretic hormone.

Question 27

Walk through the steps of regulating Blood osmolality when dehydrated, increase in salt intake, and increase in water intake.

Answer 27

See pgs 12-13 in book for detailed answer

Question 28

Many ion channels are always open, but some are gated, what is another term for a gated ion channel?

Answer 28

Voltage-Gated Channel

Question 29

What is the difference between a channel protein and a carrier protein?

Answer 29

Channels are simple open and close whereas carriers actually change their three dimensional shape. All channels are passive transport, whereas carriers are a mix of passive and active transport.

Question 30

Carrier-Mediated Transport is responsible for which types of transportation?

Answer 30

Facilitated Diffusion (passive) and Active Transport

Question 31

Non-Carrier Mediated Transport is responsible for which types of transportation?

Answer 31

Simple Diffusion
Simple Diffusion through Channels
and Simple Diffusion through Aquaporins.

Question 32

Carrier Proteins that require ATP are often called what other term?

Answer 32

Pumps