- WELCOME TO CARBOHYDRATES PART SIX.
IN THIS TUTORIAL WE'LL LOOK AT SOME OF THE OTHER
METABOLIC PROCESSES OF GLUCOSE.
THIS WILL GET DEVELOPED FURTHER
WHEN YOU GET TO YOUR BIOLOGY CLASSES,
BUT IT'S WORTH AT LEAST A BRIEF INTRODUCTION.
LET'S GET STARTED. ALL RIGHTY.
SO, WE RECOGNIZE, RIGHT, GLUCOSE IS THE--
IS THE STAR OF THE SHOW HERE, RIGHT?
SO, UPPER CASE G.
AND WE'VE LOOKED THAT IF WE HAVE TOO MUCH GLUCOSE
THEN WE CAN STORE IT AS GLYCOGEN, RIGHT?
A POLYSACCHARIDE.
SO, WE HAVE OUR MONOSACCHARIDE GLUCOSE
AND OUR POLYSACCHARIDE GLYCOGEN AND-- RIGHT?
THAT'S ALL ABOUT ENERGY STORAGE.
SO, IF WE HAVE PLENTY OF GLUCOSE AND WE'RE READY
TO STORE THEN WE DESCRIBE THAT AS GLYCOGENESIS, RIGHT?
SO, WE'RE GOING TO MAKE GLYCOGEN AND,
RIGHT, GENESIS, RIGHT,
THE CREATION OF GLYCOGEN.
SO, THAT WOULD BE HERE AND THINK ABOUT THAT IN TERMS OF--
THAT'S OUR ENERGY STORAGE MODE.
SO, WHEN ALL IS GOING WELL AND WE'RE RICH
AND HAVE LOTS TO EAT WE'RE IN GLYCOGENESIS MODE.
HOWEVER, WHEN WE NEED THAT GLYCOGEN FOR EXERCISING OR THAT,
SORT OF, THING OR WE DON'T HAVE AS MUCH FOOD,
AND SO WE NEED SOME ENERGY SOURCES, RIGHT?
SO, WE'RE GOING TO TAKE THAT GLYCOGEN AND LYSIS,
WE'RE GOING TO SPLIT IT APART.
WE'RE GOING TO-- RIGHT.
SO-- OOPS, I DON'T KNOW WHY I DID THAT IN RED, RIGHT.
SO, THEN WE HAVE ONE ENERGY AS NEEDED.
OKAY. SO, THE-- RIGHT.
SO, REMEMBER TO THINK ABOUT GLYCOGEN
IS BASICALLY ANIMAL STARCH,
THAT MIGHT BE HELPFUL TO WRITE IN. RIGHT.
SO, IT'S A POLYSACCHARIDE, RIGHT.
AND YOU CAN THINK OF IT AS ANIMAL STARCH,
HOW WE STORE SUGAR.
ALL RIGHTY.
WE WON'T LOOK CLOSELY AT THIS NEXT BRANCH,
BUT GLUCOSE CAN BE CONVERTED INTO RIBOSE
WHICH WE NEED FOR R AND A,
AND SO BECAUSE WE'RE GOING FROM A SIX-CARBON SUGAR
TO A FIVE-CARBON SUGAR,
WE CALL THIS THE PENTOSE PATHWAY.
AND THAT'S ALL WE'RE GOING TO REALLY SAY ABOUT THAT RIGHT NOW,
NOT TOO MUCH TO SAY THERE.
BUT NOW WE WILL LOOK AT THESE IMPORTANT PATHWAYS, RIGHT?
SO, GLUCOSE TO PYRUVATE
WE'VE STUDIED THAT IN GREAT DETAIL, RIGHT?
THAT IS GLYCOLYSIS, AND SO THAT'S RIGHT HERE.
AND THEN ONE LAST TERM IS WHAT HAPPENS--
WHAT HAPPENS IF WE'RE RUNNING SHORT ON GLUCOSE?
BUT WE NEED PYRUVATE OR WE NEED ENERGY.
SO, THEN WE HAVE THE TERM GLUCONEOGENESIS, RIGHT?
SO, HERE IS WHERE WE GET THE BREAKDOWN OF PROTEINS
IN THE LIVER TO FORM GLUCOSE FROM AMINO ACIDS, RIGHT?
SO, THIS IS A, LIKE A NEW SOURCE, RIGHT?
SO, OUTSIDE OF THE CARBOHYDRATES, RIGHT?
SO, GETTING GLUCOSE FROM NON-CARBOHYDRATE SOURCES.
AND SO THAT WOULD BE GLUCONEOGENESIS RIGHT HERE.
OKAY. SO, I'VE GOT THIS ALL BROKE DOWN,
THERE'S THAT ONE. OKAY.
SO, YOU WANT TO BE FAMILIAR
WITH THESE TERMS AND BE ABLE TO, RIGHT.
IF I WAS TO OBSCURE THESE LABELS,
YOU SHOULD BE ABLE TO FILL IN THE BLANKS,
COMPLETE THE DIAGRAM USING THE TERMS
THAT WE HAVE JUST BEEN INTRODUCED TO.
AND THEN LET'S LOOK AT THIS VERY BRIEFLY IN TERMS
OF THE REGULATION OF GLUCOSE WITH ENERGY METABOLISM.
ALL RIGHT.
SO, THERE ARE TWO MAIN HORMONES
THAT ARE SECRETED BY THE PANCREAS
THAT PLAY A MAJOR ROLE IN GLUCOSE METABOLISM.
SO, ONE IS FOR AFTER WE'VE EATEN, RIGHT?
SO, RIGHT AFTER WE EAT, WE ARE GOING--
WE'RE GOING TO HAVE A RISE IN BLOOD GLUCOSE
BECAUSE WE'RE GOING TO START BREAKING DOWN THE FOODS
IN OUR BODY TO GET THE GLUCOSE.
AND SO AT THAT TIME THE PANCREATIC BETA CELLS
WILL RELEASE INSULIN, RIGHT?
AND SO THE RELEASE OF INSULIN ALLOWS GLUCOSE
TO ENTER CELLS FASTER.
IT BREAKS DOWN THE GLUCOSE BY GLYCOLYSIS.
IT HELPS WITH GLYCOGEN SYNTHESIS INCREASING
AND IT HELPS WITH THE SYNTHESIS OF LIPIDS AND PROTEINS, RIGHT?
SO, IT'S ALL ABOUT BREAKING DOWN
THAT FOOD AND SO WE CAN USE IT FOR ENERGY AND TO MAKE OTHER
IMPORTANT BIOLOGICAL MOLECULES.
NOW, WHEN WE HAVE A FALLING--
A FALLING BLOOD GLUCOSE LEVEL,
THIS MEANS THAT WE'VE EITHER BEEN FASTING,
RIGHT, OR WE'RE STARVING, RIGHT?
SO, SOMETIMES IT'S INTENTIONAL AND SOMETIMES IT'S NOT.
SO, THEN THE PANCREAS IS GOING TO RELEASE
THE ALPHA CELL FROM THE--
FROM THE PANCREATIC ALPHA CELLS,
THEY WILL RELEASE GLUCAGON, RIGHT?
SO, GLUCAGON IS ALL ABOUT GLUCOSE ENTRY
TO THE CELLS HAS SLOWED DOWN,
SO THAT MEANS WE HAVE TO START BREAKING DOWN GLYCOGEN.
AND WE'RE GOING TO START LOOKING AT OTHER SOURCES
OF ENERGY BREAKING DOWN THOSE PROTEINS,
TO GET GLUCOSE.
AND THAT'S WHERE GLUCONEOGENESIS STARTS, RIGHT?
SO WE--
IF WE CONNECT THIS NOW TO UP ABOVE, RIGHT?
SO, THIS WOULD BE THE GLYCOGENOLYSIS, RIGHT?
AND THIS WOULD BE THE GLUCONEOGENESIS HAPPENING HERE.
AND THEN CONVERSELY WITH INSULIN, RIGHT,
GLYCOGEN SYNTHESIS, SO THAT WOULD BE GLYCOGENESIS.
AND THEN OF COURSE THERE'S GLYCOLYSIS.
SO, ANOTHER IMPORTANT APPLICATION
OF THE TERMS WE'VE DEFINED IS LOOKING AT THEIR ROLE
AND WHETHER THEY'RE THERE
AFTER WE EAT OR WHEN WE'RE FASTING OR STARVING.
SO, THOSE ARE THE CONNECTIONS
THAT YOU WANT TO MAKE BETWEEN THE FOUR--
THE FOUR PATHWAYS AND WHERE THEY WOULD SHOW UP IN A SCHEMATIC,
AND WHERE THEY WOULD SHOW UP IN OUR DAY TO DAY--
THE DAY TO DAY RHYTHMS OF LIFE.
WHETHER WE'VE JUST EATEN OR IT'S BEEN A WHILE.
SO, THEN I WANT TO LOOK A LITTLE MORE CLOSELY IN THIS LAST PAGE,
AT EXACTLY
WHAT HAPPENS WHEN WE'VE BEEN FASTING OR STARVING, RIGHT.
SO, SOME OF THESE IS A PARAPHRASE
FROM THE PREVIOUS PAGE.
NOW, INSTEAD OF WORDS WE'RE SEEING IT IN A DIAGRAM.
ALL RIGHT.
SO, HERE WE COULD SO THAT THIS IS THE HOURS OF STARVATION.
SO, ZERO WOULD BE WE'VE JUST FINISHED EATING. OKAY.
SO, WHEN WE'VE JUST FINISHED EATING WHAT WE--
WHAT WE SAW IN THE PREVIOUS PAGE WAS,
RIGHT, INSULIN'S RELEASED.
INSULIN TRIGGERS THAT WE ARE GOING TO, RIGHT,
THAT WE WILL BE PRODUCING GLYCOGEN AND-- YOU KNOW,
GLYCOLYSIS THAT, SORT OF,
THING RIGHT THERE. ALL RIGHTY.
SO, RIGHT AFTER WE'VE EATEN WE'RE GOING TO HAVE GLYCOGENESIS
AND GLYCOLYSIS OCCURRING.
AND SO THAT LEADS TO--
WHAT DO I WANT TO SAY THERE?
ALL RIGHT. I THINK THAT'S ENOUGH.
NOW, LET'S LOOK AT WHAT HAPPENS, RIGHT.
SO, ONCE WE FINISHED EATING, INSULIN RELEASED.
OKAY, AND SO--
AND THAT'S GOING TO TRIGGER GLYCOLYSIS AND GLYCOGENESIS.
NOW, THE PART
THAT I WANT TO LOOK AT A LITTLE MORE CLOSELY THEN IS WE GET
THIS GRADUAL DECLINE IN BLOOD SUGAR.
SO, AS THE BLOOD SUGAR DECLINES, RIGHT,
THAT'S GOING TO TRIGGER THE RELEASE OF THE GLUCAGON.
ALL RIGHT.
AND SO, RIGHT, SO THE LOWERING
OF BLOOD SUGAR TRIGGERS THE RELEASE OF GLUCAGON,
AND SO THEN WHAT THAT DOES IS TO NOT TRIGGERS THE GLYCOGENOLYSIS
AND THE GLUCONEOGENESIS.
AND SO, WE SEE THAT WE START TO GET
A BUILD UP OF FREE FATTY ACIDS,
AND WE SEE OUR LIVER GLYCOGEN STARTS TO DROP.
AND THEN THIS IS THE KEY PART THAT I WANTED TO TALK ABOUT.
WE'LL SEE A RISE IN THE KETONE BODIES, RIGHT?
SO, EVERYTHING IN RED IS, RIGHT,
TRIGGERED BY FASTING.
ALL RIGHTY. OKAY.
SOMETHING THAT'S VERY INTERESTING-- OKAY.
SO, LET'S KEEP TALKING ABOUT THE KETONE BODIES FOR A MINUTE.
SO, THE KETONE BODIES FORM FROM AN EXCESS OF ACETYL-COA
AND IT'S INTERESTING BECAUSE BRAIN AND OTHER TISSUES
CATABOLIZE THE KETONE BODIES TO PRODUCE ATP.
SO, IT'S BASICALLY
LIKE THE KETONE BODIES ARE AN EMERGENCY ENERGY SOURCE
BECAUSE WE'RE NOT GETTING FOOD,
WHETHER WE'RE CHOOSING TO FAST OR BECAUSE NONE IS AVAILABLE.
SO, I FIND THIS NEXT PART FASCINATING.
SO, PEOPLE WITH DIABETES MELLITUS,
BIOCHEMICALLY THERE'S SOMETHING
GOING ON THAT PREVENTS THE GLUCOSE
FROM BEING UTILIZED OR STORED RELATED TO THE INSULIN.
AND THERE'S A COUPLE REASONS
THAT COULD CAUSE THAT AND YOU'LL LEARN MORE
ABOUT THAT IN YOUR BIO.
BUT THE POINT IS, BASICALLY THAT A PERSON
WITH DIABETES AND THE ESSENCE IS STARVING TO DEATH
BECAUSE THE BODY CANNOT UTILIZE THE GLUCOSE,
IT HAS TO GO INTO THE GLUCONEOGENESIS
AND STARTS BREAKING DOWN FATS.
AND THE CONSEQUENCE WHETHER WE ARE FASTING OR WE HAVE DIABETES,
WE GET A BUILD UP OF ACETYL-COA.
AND THAT ACETYL-COA LEADS TO THE FORMATION
OF THE KETONE BODIES.
SO, NOW WE WANT TO LOOK A LITTLE MORE CLOSELY
AT THIS KETONE BODIES.
ALL RIGHT.
SO, HERE WE HAVE TWO MOLECULES YOU SHOULD RECOGNIZE, RIGHT?
THIS IS THE ACETYL-COA
AND WE HAVE A BUILD UP, RIGHT?
SO, THROUGH THAT BUILD UP OF ACETYL-COA THEN
THE ACETYL-COA MOLECULES START REACTING WITH EACH OTHER
PRODUCING COENZYME A,
AND THEN HERE ARE THE KETONE BODIES.
OKAY. SO, IN THE SHORT TERM,
IT'S AN EMERGENCY SOURCE, BUT LONG TERM,
RIGHT, IF THE CONCENTRATION OF T--
KETONE BODIES BECOMES TOO HIGH,
SO THIS CAN HAPPEN FROM DIABETES
OR VERY LITTLE CARBOHYDRATE DIET.
IT ACTUALLY CREATES KETOACIDOSIS
BECAUSE IF WE LOOK HERE, RIGHT,
WE CAN SEE THAT WE HAVE A LOT OF ACIDIC GROUPS
AND THEN WE CAN SEE THAT WE HAVE THE KETONES.
SO, WE CAN SEE WHY THEY GET CALLED KETONE BODIES.
AND THEN WE RECOGNIZE THE ACIDITY THERE
WITH THOSE CARBOXYLIC ACID GROUPS.
ALL RIGHT.
SO, THE KETONE BODIES CANNOT BE COMPLETELY METABOLIZED.
SO, ACETONE, RIGHT, SO HERE IS ACETONE.
LET'S SEE WHERE IS AT? RIGHT.
SO, THERE'S ACETONE RIGHT THERE,
RIGHT. SO, THERE'S ACETONE.
SO, IF WE EXERCISE REALLY AGGRESSIVELY
OR IF WE'RE WITH SOMEBODY THAT HAS DIABETES,
WE CAN ACTUALLY SMELL THE ACETONE ON THE BREATH.
AND SO A LOT OF TIMES WHEN SOMEONE IS INCOMING
INTO A HOSPITAL OR TO A MEDICAL CLINIC,
JUST THE SIMPLE SMELLING OF ACETONE ON THE BREATH LET'S A--
LET'S A MEDICAL CARE PROVIDER KNOW ABOUT A LOT OF INFORMATION.
ALL RIGHT.
AND THEN WE CAN SEE THAT THE PH OF THE BLOOD DECREASES AND SO
THIS AFFECTS THE ABILITY OF THE HEMOGLOBIN TO CARRY OXYGEN,
BREATHING CAN BECOME DIFFICULT,
AND KETOACIDOSIS CAN ACTUALLY LEAD TO COMA OR DEATH.
SO, IT'S ANOTHER IMPORTANT ASPECT OF GLUCOSE METABOLISM
TO LOOK AT OR ACTUALLY THE LACK
OF GLUCOSE METABOLISM LEADS TO THE FORMATION
OF THESE KETONE BODIES WHICH IN THE SHORT TERM PROVIDE ENERGY,
BUT DO HAVE LONG TERM HEALTH EFFECTS
IF OUR BODIES STAYS IN THAT STATE.
SO, PLEASE TAKE SOMETIME NOW TO WORK A FEW HOMEWORK PROBLEMS
TO REINFORCE YOUR UNDERSTANDING.