Metabolism Please Lord

Metabolism

The chemical process that occurs within an organism in order to maintain life.

Anabolism

The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism

Catabolism

The breakdown on complex molecules in living organisms to form simpler ones, together with the release of energy, destructive metabolism

Summarize local and hormonal regulation of metabolism

Local metabolism serves the needs to an individual cell, hormonal regulation defends the entire organism

Name the three major categories of energy expenditure

Basal metabolic rate (60-70 percent), Thermogenesis (dietary and obligatory, 5-15%), physical activity (20-30%)

Outline how the brain utilizes nutrients

The brain does not store energy; it requires glucose but can use ketones

Outline how the heart utilizes nutrients

The heart does not store energy; the heart requires glucose but can use fatty acids and ketones

Outline how the liver utilizes nutrients

The liver exports glucose only, it can synthesize glucose (also called gluconeogenesis) and release glucose from glycogen (glycogenolysis)

Outline how the adipose tissue utilizes nutrients

Most energy reserves are contained in adipose tissue

Indicate the primary circulating form and storage form (including location) of carbs

Circulating form is glucose, it is stored in the liver and muscle as glycogen

Indicate the primary circulating form and storage form (including location) of proteins

The primary circulating form and storage form is amino acids, and it is stored in the muscle only

Indicate the primary circulating form and storage form (including location) of fats

The primary circulating form is free fatty acids, and the primary storage form is fat in adipose tissue

Define glycogenesis, glycogenolysis, gluconeogenesis and glycolysis. Under which circumstances (feed or fast) would each of these processes occur?

Look at Quizlet for definition. Come back to card with answers regarding feeding and fasting

Describe how glucose enters cells and which tissues require insulin.

Glucose requires a carrier to cross the cell membrane, so they must utilize carrier proteins called GLUTS in order to enter the cell by sodium independent facilitated diffusion. GLUTS are bidirectional AND REGULATED BY INSULIN. Everything but the GI tract, kidney and brain require insulin.

Outline the pathway/steps for glucose under anaerobic conditions

Glucose -Pyruvate-Lactate

Outline the pathway/steps for glucose under aerobic conditions

Glucose-Pyruvate-AcetylCoa-TCA cycle-Oxidative phosphorylation for ATP

Name the two hormones that exert major hormonal regulatory control on glycolysis

Insulin and glucagon (insulin stimulates production of pyruvate in a fed state, glucagon inhibits pyruvate production when in a fasting state or during diabetes

Explain why maintenance of blood glucose in the brain is critical for brain function

A concentration gradient must be present in the brain, and this concentration is usually established through glucose (obligate glucose user)

Name the four “counter-regulatory” hormones

Catecholamines, glucagon, cortisol and growth hormone

Explain how FAs circulate in the bloodstream, enter cells and enter mitochondria.

FFAs are released from fat via lipolysis and bind to albumin. Then, the FFAs are released into the bloodstream. FFAs enter the mitochondria via carnitine transport and undergo beta oxidation in the mitochondria to yield Acetyl CoA.

List three pathways for FA’s in the hepatocyte.

SPEND by undergoing complete beta oxidation for energy, SAVE by forming triglycerides that travel as lipoproteins in the blood or CONVERT to ketones that occurs during the fasting state

Compare the roles and mechanisms of lipoprotein lipase and hormone lipase. Describe what could happen if there was a defect in the function of lipoprotein lipase.

Lipoprotein lipase acts upon chylomicrons and lipoproteins to release FAs to adipose tissue, skeletal and cardiac muscle. Insulin stimulates lipoprotein lipase. Hormone lipase allows FAs to be released from TAGs. Hyperlipidemia could occur if lipoprotein lipase did not function properly.

Outline the pathway/steps for amino acid utilization by cells; include what happens to the by-product, NH3,
that is generated from transamination

Amino acids can either be converted to intermediates in TCA, Acetyl CoA or Pyruvate. NH3 is processed through the urea cycle. 

Describe the conditions from which ketones are formed and name the organ that synthesizes ketones

Ketones are synthesized from the liver by Acetyel-CoA. Ketones are formed during the fates state, during diabetes mellitus, excessive acetyl-CoA formation, and can lead to ketoacidosis if excessive.

Outline the pathway/steps for ketone utilization by cells, and which tissues can use them.

Converted to Acetyle CoA-TCA cycle-Oxidative Phosphorylation-Making ATP. Both the brain and the heart can utilize ketones.

Name the three ketone bodies and explain which one is not metabolizable

ACETONE IS NON-METABOLIZEABLE, Acetoacetate (dissociates to acetoacetic acid), and beta-hydroxybutyrate (dissociated to beta hydroxybutyric acid

Describe the condition under which lactate is produced and give two examples.

Lactate is produced with no oxygen, such as intense exercise or shock

Explain what the Cori cycle is and what it’s purpose is

When exercising, lactate is generated and enter circulation. Lactate then is converted to glucose in the liver and released back into circulation

Explain how plasma lactate level could provide information about the severity of circulatory shock

If circulatory shock occurs, there will be a lack of oxygen in the system. Due to decreased ATP from the inability to undergo oxidative phosphorylation, cells will rely on anaerobic glycolysis. This will lead to a higher concentration of lactate in circulation, which could be an indicator of lactic acidosis.

List two other names for the TCA cycle and explain how it is regulated

Two other names for the TCA cycle is the Krebs cycle and the citric acid cycle.

Explain the inability to convert pyruvate to Acetyl-CoA can damage the brain in ruminants with Thiamine deficiency. 

In order to convert pyruvate to Acetyl-CoA, thiamine is utilized in the pyruvate dehydrogenase complex. IF thiamine deficiency occurs, animals could suffer from polioencephalomalacia, leading to dysfucntion of the rumen from not receiving an adequate supply of energy from Acetyl-CoA.

Describe where cellular respiration occurs, where it occurs, what is required and explain why it is important.

Define glycogen and name where it is stored. Describe the main advantage of glycogen as a fuel source.

Glycogen is a branched chain polysaccharide of glucose. Muscle glycogen fuels muscle activity.

Contrast how the liver and skeletal muscle use glycogen

Liver utilizes glycogen to maintain blood glucose levels, muscle glycogen fuels muscle activity. If the liver is at maximum glycogen storage, excess glucose is redirected to FA synthesis

Outline the pathway/steps for gluconeogenesis and where it occurs. Name the conditions under which it would occur and the hormones that stimulate it to occur.

Glucose-Phosphoenylbutyrate-Pyruvate-Pyruvate Dehydrogenase-Acetyl-CoA-TCA cycle-ATP. It would occur during the fasting state, as glucagon would have to be released and low blood glucose levels would have to occur. Glucocorticoids and catecholamines (cortisol, epinephrine, norepinephrine) would have to be released for gluconeogenesis to occur.

List the substrates that can be used for gluconeogenesis and name the one that is specific to ruminants.

Amino acids, lactate, glycerol, OAA and propionate (ruminants) are substrates can be utilized in gluconeogenesis.

Describe what happens when there are a massive fat mobilization and the amount of Acetyl-CoA that can be formed is saturated.

Hepatic lipidacidosis: liver cannot keep up

Describe what happens is there is massive fat mobilization and the liver’s ability to form lipoproteins is saturated or impaired

Pregnancy toxemia, increased mobilization overwhelms the liver’s capacity

Describe how the body stores/mobilizes food and energy

Storage form is triglycerides, pass through circulation as a lipoprotein or chylomicron

Describe the utilization of each of the VFA’s in ruminants

Propionate: the only one considered gluconeogenic; converted to OAA-can be used for gluconeogenesis

Butyrate: mainly used by the rumen wall

Acetate: produced in the largest amount and combines with coenzyme A to make Acetyl-CoA and can enter TCA cycle or be used to make ketones

Explain how energy (ATP) can be utilized during starvation