Learning about Biology & Nature!

Nutrition in the Brain

2005-03-31T19:33:00.000+08:00

Some simple Facts about The Brain and Metabolism

Weighs 2% of total body weight
Recieves 15% of cardiac Output
20% of total body oxygen consumption
25% of total body glucose utilzatoin

*Please Click on the link for a simplified overview of the Brain and Nutrition =)

The "Chim" Stoichiometric calculations

From a global blood flow of 57 ml/100 g·min, the brain extracts approximately 50% of oxygen and 10% of glucose from the arterial blood. Hence, the glucose utilization of the brain, as assessed by measuring the arterial–venous difference, is 31 mmol/100 g·min.

Oxygen consumption is 160 mmol/100 g·min; because CO2 production is almost identical, the respiratory quotient (RQ) of the brain is nearly 1, indicating that carbohydrates are the substrates for oxidative metabolism. Given a theoretical stoichiometry of 6 mmol of oxygen consumed for each mmole of glucose, glucose utilization by the brain should in theory be 26.6 mmol/100 g·min.

However, the measured glucose utilization is 31 mmol/100 g·min, indicating that an excess of 4.4 mmol/100 g·min of glucose follows other metabolic fates.

What has happened to the Missing Glucose?
Glucose can produce metabolic intermediates, such as lactate and pyruvate, which do not enter necessarily in the tricarboxylic acid cycle but rather can be released and removed by the circulation. Glucose can be incorporated into lipids, proteins, and glycogen, and it is also the precursor of certain neurotransmitters such as g-aminobutyric acid (GABA), glutamate, and acetylcholine (10, 60).

Deep Sea Fishes and Pressure

2005-02-26T12:58:00.000+08:00

Water pressure in the Deep Sea = 1000 times at the surface

Q: How do Deep Sea fishes survive at such high Pressures? Won't they be crushed?
A: As long as there is no pressure difference between the water and the body of the fish, it would not be crushed.

Examples of Deep Sea Fishes:
- Lantern Fish
- Green Eye
- Angler Fish

Biological Adpatations
- Swim Bladder: Produces Gas of similar pressure to surrounding water pressure
- Gelatinous muscles with a high water content, so that the pressure that is being exerted on them is exerted over their entire body.

Resources
1. Creatures of the Deep: Teachers Resources
http://www.teachers.ash.org.au/jmresources/deep/creatures.html

2.Life and Living in the Deep Sea
http://www.mesa.edu.au/seachange/97/deepsea.htm

3. Marine Biology
http://www.marinebio.com/Oceans/TheDeep/

4.Deep Sea Biology - Research
http://people.whitman.edu/~yancey/deepsea.html

5.Pictures: Deep Sea Beastiary

Cruise to Antarctica!

2005-01-17T13:27:00.000+08:00

Been watching alot of discovery and national geographic lately... Wish I had subscribed to them earlier! Imagine the difference it would have made if I had watched them from young!
Now I remember why I took up lifesciences instead of philosophy or literature.... Because I love Nature! Why am I cooped up at home? Can't wait to organise nature walks and hiking expeditions once again!

Cruise to Antarctica!
for US$13,000, you can cruise in a ice breaker ship! The ship actually rides over the ice and propels itself through the ice to reach inland! The wildlife, the views are simply astounding! Read more here! http://www.quarkexpeditions.com/brochures/UltimateAntarctica04-05.pdf

How Tsunamis Work

2005-01-05T13:09:00.000+08:00

http://www.howstuffworks.com/tsunami.htm

National Geopgraphic Pictures of the YEAR 2004

2004-12-14T21:39:00.000+08:00

It is my dream to be able to take such brilliant photos!
Lovely!