Cellular Phys

Question 1

What are the 3 buffer systems of the body? Which is the most important?

Answer 1

BICARB

• pK 6.1
• the 2 components can be individually regulated by respiration and renal excretion
• dual regulation makes it ideal

PHOSPHATE

• pK 6.8
• ideal buffer but concentration is low

PROTEINS

• many have pK close to physiological
• protein buffering capacity limited mainly to intracellular

Question 2

How is phosphorylcreatine synthesised?

Answer 2

• Glucose in the bloodstream enters cells, where it is degraded to pyruvate
• When adequate O2 is present, pyruvate enters the citric acid cycle and is metabolized (aerobic glycolysis)
• This metabolises glucose/glycogen to CO2 and H2O to form large quantities of ATP and ADP
• ATP in the mitochondria transferrs its phosphate to creatine
• Phosphorylcreatine can then be hydrolysed to form ATP from ADP
• During exercise, much of the energy for phosphorylcreatine and ATP resynthesis comes from the breakdown of glucose

Question 3

What are Gap junctions, where are they found on the cell and what is their main function?

Answer 3

• units called connexons line up with eachother
• found on lateral walls
• gap junctions permit rapid propagation of ions/sugars/amino acids from cell to cell

Question 4

What does pK represent? How do I interpret a higher vs lower pK?

Answer 4

pK is the logarithmic value of the dissociation constant

• The smaller the value of pKa, the stronger the acid
• The smaller the value of pKb, the stronger the base

Question 5

Where and from what is Nitric Oxide synthesised?

Answer 5

Synthesised from arginine in the brain and endothelium (also known as endothelium derived relaxing factor EDRF)

Question 6

What is osmotic pressure?

Answer 6

The pressure necessary to prevent solvent migration from one side of semi-permeable membrane to the other down the concentration gradient

Question 7

What is the number of ions of sodium and potassium transported when the Na/K ATPase pump is activated?

Answer 7

3Na out

2K in

Question 8

Describe two biological causes of intracellular oedema.

Answer 8

Depression of metabolic systems
Lack of adequate nutrition

• ionic pumps become depressed
• sodium that leaks in cannot be pumped out
• osmosis causes intracellular oedema

Question 9

What are the substances released by basophils when activated?

Answer 9

• histamine
• heparin
• serotonin
• bradykinin

Question 10

What is the input and output of the citric acid cycle

Answer 10

Acetyl CoA is metabolised to Co2 and H atoms producing

• 12 ATP
• 2 total H20 (4 produced, 2 used in cycle)
• 1 NADH
• 1 FADH2
• 1 GTP

Question 11

Is the net production of ATP greater with aerobic or anaerobic conditions?

Answer 11

During aerobic glycolysis the net production of ATP is 19 times greater than the 2 ATPs formed under anaerobic conditions.