Lecture 5 - Composition of the extracellular environ.

Question 1

Extracellular Environment

Answer 1

• Fluid compartment with dissolved molecules, a polysaccharide, & protein matrix
• Extracellular environment includes all constituents of the body located outside of the cells.
• Approx. 67% of the total body water is contained within cells & 33% in the extracellular environment
• Blood plasma contains 20% of this extracellular fluid
• Remaining 80% is interstitial fluid (between tissues)

Question 2

Extracellular matrix

Answer 2

• Organization of molecules linked to fibers of collagen, elastin, & carbohydrates outside the cell’s plasma membrane
• Ground substance gel is composed of glycoproteins & proteoglycans
• Collagen & elastin fibers provide structural strength to the connective tissues

Question 3

What are integrins?

Answer 3

glycoproteins integrating the extracellular to the intracellular environments

Question 4

What does MMP stand for?

Answer 4

Matrix metalloproteinases

Question 5

What are MMPs?

Answer 5

Enzymes that can break down extracellular matrix proteins (calcium-dependent zinc-containing endopeptidases)
- Required for tissue remodeling (wound healing) & for migration of phagocytic cells & other WBCs during fight against infection
- Allow tumor cells to migrate across the basement membrane and into blood & lymphatic vessels
- Destruction of cartilage protein in arthritis may also involve the action of MMPs
- Imbalance between the MMPs and TIMPs is believed to contribute to cardiovascular & neural disease

Question 6

What are the 2 major categories of transport across the plasma membrane?

Answer 6

Carrier-mediate transport & Non-carrier-mediated transport (Passive transport)

Question 7

What is passive transport?

Answer 7

molecules & ions move across a membrane from higher to lower concentration (down a concentration gradient)

Question 8

What is active transport?

Answer 8

occurs against the concentration gradient (pumps)

Question 9

What are the 3 types of passive transport?

Answer 9

1, Simple diffusion through the double phospholipid layers
2. Ions move by simple diffusion through protein channels
3. Facilitated diffusion of glucose GLUTs undergo a conformational change to release the molecule on the other side of the membrane

Question 10

Na+/K+ pumps move how many Na+ and K+, and in what direction against their concentration gradients?

Answer 10

Pumps more 3 Na+ (out) & 2 K+ (in) opposite directions

Question 11

What enzyme does the Na+/K+ pump use for ATP energy to pump the ions against their gradients?

Answer 11

Na+/K+ ATPase

Question 12

In the kidneys (SGLT2) has what ratio of Na+ to glucose?

Answer 12

1:1

Question 13

In the small intestine (SGLT1), has a ratio of how many Na+ to glucose?

Answer 13

2:1

Question 14

Secondary Active Transport (Coupled Transport)

Answer 14

Sodium-coupled glucose transporters (SGLT)

Question 15

Diffusion through a dialysis membrane

Answer 15

• The dialysis membrane is semipermeable with pores of a certain size.
• Proteins inside the dialysis bag are too large to get through
• The plasma membrane allows diffusion of nonpolar molecules such as oxygen gas or steroid hormones
• Uncharged small molecules with polar covalent bonds (CO2, ethanol, urea) are able to penetrate the phospholipid bilayer

Question 16

The greater the solute concentration, the greater the what?

Answer 16

osmotic pressure