Integration of metabolism Flashcards
What organs and molecules are the primary, junctional focus of all metabolic pathways?
- liver, as it can carry out all processes
- junction points: G-6-P, pyruvate, acetyl CoA
What pathways occur in the cytosol?
- glycolysis
- pentose phosphate pathway
- fatty acid synthesis
What pathway occurs in the mitochondrial matrix?
- citric acid cycle
- oxidative phosphorylation
- B-oxidation of fatty acids
- ketone body formation
What occurs in both cytosol and mitochondrial matrix?
- gluconeogenesis
- urea synthesis
What molecules can all form Acetyl CoA, to then enter TCA and ox phos?
- glucose
- fatty acids
- amino acids
Lipid and amino acid breakdown stimulated by glucocoritcoids in the liver produces what?
- ketone bodies in the blood
- -produce ATP at specified site
Glucogenesis and glycogenolysis in the liver, stimulated by glucocorticoids andd epinephrine produce what?
-glucose used in neural tissue for ATP production
What stimulate glucogenesis and glycogenolysis in the liver?
- glucocorticoids
- epinephrine
- glucagon
Where does triglyceride (TAG) breakdown occur?
-adipose tissue, when energy is required and body is in starvation mode
What is produced from TAG breakdown?
-Fatty acids, that form ATP, except in the neural tissue
Protein breakdown by cathepsins occurs where?
skeletal muscle, to produce glucose for energy burning
What are the final products when cathepsin breaks down proteins in skeletal muscle?
- formation of amino acids, which generate gluconeogenesis and ketone bodies
Glycogen breakdown and glycolysis occurring in skeletal muscle produce what compounds for what purpose?
- lactic acid for gluconeogenesis
What does the pancreas secrete?
- insulin during high BG
- glucagon during low BG
What does the liver process?
- fats
- carbohydrates
- proteins
What is the liver able to synthesize?
- lipids
- ketone bodies: during starvation
- glucose: during starvation
What can the liver convert to protect the body?
- reduces the nitrogen balance by converting nitrogen to urea
What is the primary task of the small intestine?
-absorb nutrients from diet and move them into blood of lymphatic system
What is the primary task of skeletal muscle?
-consume mass amounts of ATP so we can live our lives
Adipose tissue is used for what purpose?
-synthesize, store, mobilize TAG
The liver is referred to as the #1 metabolic player, why?
- rapid response to dietary conditions and rapid enzyme turnover
- processes toxins and wastes; send to urea
- form plasma proteins
- compensates for nutrient fluctuations in blood
Where does the liver receive the majority of its energy?
ß-oxidation of fatty acids
Glucagon and epinephrine act on what structures?
- adipocytes to release FA’s and glycerols
- FA are transported in blood via albumin
What constitutes as anaerobic activity?
- bursts of heavy activity.
- use phosphocreatine to generate creatine for 10 s energy burn
- creatine converts back during rest
Explain the Cori cycle and why it can’t sustain for prolonged periods of time.
- conversion of glycogen to lactate; lactate to glucose (in liver) then glucose used in muscle for burning
- Liver uses ATP for glucogenesis and will burn out energy source eventually
What makes the brain so susceptible to ischemia during a stroke or other type of blood flow inhibiting process?
- no energy stores at all
- therefore brain tissue dies rapidly
How much oxygen does the brain use when a person is at rest?
- 20% and it is only 2% of our body mass
During the starvation process, how does the brain survive?
-produces ketone bodies from acetyl CoA
What is specific about cardiac tissue, and without this molecule will lead to cardiac arrest?
-aerobic respiration.
unable to generate energy anaerobically, therefore lack of O2 leads to death
What is the effect of insulin on blood glucose?
- decreases BG
- promotes storage as TAG or Glycogen
How does insulin bind?
- binds to tyrosine kinase receptor, which forms a dimer on the surface of cell to activate cAMP
- generates long term and immediate processes
How does epinephrine produce an effect?
-use of GPCR which form cAMP second messengers
What effect does glucagon have on blood glucose?
- promotes the production and release of glucose by the liver
- insinuates starvation mode
How does glucagon produce a signaling effect?
-use of GPCR
What molecule regulates most, if not all, of energy balance in the cells?
-AMP-activated protein kinase
When will AMP-activated protein kinase be active?
-is active with high levels of AMP, as there are low levels of ATP
What happens is ATP levels are high, to AMP-activated protein kinase?
- the enzyme will be deactivated, as no new energy is required to be made at the time
Explain why ATP and AMP are able to regulate the activation of AMP-activated protein kinase.
- ATP and AMP compete for binding sites on the kinase.
- -high levels of ATP will block AMP, and render the kinase inactive.
What is the primary purpose of leptin, and what happens if it is destroyed?
- leptin signals the brain when you are full to stop eating.
- if inactive, person will never feel full
Describe one hypothesis as to what may be a potential cause of obesity, rather than poor diet.
-TKR are activated by leptin. It is possible that the specific TKR become tolerant of the [leptin] signal and begin to produce more weak signals, conveying the feeling of not being “full”
What components contribute to the tolerance or weakening of the signal that is generated by the leptin TKR?
- suppressors of cytokine signaling (SOCS)
The SIR2 gene may contribute to what?
- extend life longevity
Where do sirtuins come from?
-generated from NAD+-dependent protein deacetylase reactions
What is the effect of high ATP on NAD+ and NADH?
- high ATP levels will result in shut down of TCA cycle, which will reduce the amount of NADH, and increase the amount of NAD+
What effect will high ATP levels have on oxidative phosphorylation?
- the TCA cycle will shut down reducing NADH available. Less NADH will reduce the activity and production of ATP.
NAHD is a primary electron carrier in Oxidative Phosphorylation.
With high ATP levels what is pyruvate going to form?
- will not likely form acetyl CoA
- will form OAA, lactate, alanine
