Regulation of Metabolism (Tissue-Specific and Hormonal) Flashcards
Which metabolic pathways produce CO2?
- Oxidative decarboxylation
- TCA cycle
- Oxidative phosphorylation
________ play a significant role in the integration of mammalian metabolism
Hormones
Give examples of types of hormones.
- Peptide
- Catecholamine
- Eicosanoid
- Steroid
What are the two major endocrine glands?
- Pituitary
- Hypothalamus
Which glands produce steroid hormones?
Ovaries and testes
Which gland releases insulin and glucagon?
Pancreas
Which gland releases leptin?
Adipose tissue
What is the negative feedback regulation of hormones?
- A signal from the central nervous system leads to the production of hormones in an endocrine gland
- The end-product (hormone) inhibits its own production by blocking the hypothalamus
Which structure is responsible for:
o Transports ions to maintain membrane potential
o Integrates inputs from the body and surroundings
o Send signals to other organs
Brain
Which structure is responsible for:
o Uses ATP generated aerobically to pump blood
Cardiac muscle
Which structure is responsible for:
o Synthesizes, stores, and mobilizes triacylglycerol
o Brown adipose tissue carries out thermogenesis
Adipose tissue
Which structure is responsible for:
o Uses ATP generated aerobically or anaerobically to do mechanical work
Skeletal muscle
Which structure is responsible for:
o Process fats, carbohydrates, proteins from the diet
o Synthesizes and distributes lipids, ketone bodies, and glucose for other tissues
o Converts excess nitrogen to urea
Liver
Which nutrients do hepatocytes metabolize?
Carbohydrates, amino acids, and lipids
What varies the nutrient supply?
Diet and feeding
What varies the precursor requirement?
Level of activity and health
Why is the liver capable of maintaining balance between nutrient supply and precursor demand?
Remarkable flexibility in “enzymatic machinery”
What are hepatocyte enzymes sensitive to?
Various hormones (insulin, glucagon, epinephrine, leptin)
Which glucose transporter is not inhibited by glucose-6-phosphate? What is the consequence?
- Hexokinase IV
- The liver may easily supply glucose to other tissues, as it does not use glucose
Where is Glucose-6-Phosphate diverted to?
- Pentose phosphate pathway
- Glycolysis
- Production of liver glycogen
Where does the pyruvate from glycolysis enter in the liver? Which is more common?
- Fatty acid and cholesterol synthesis (more common)
- Enters the TCA cycle
When do hepatocytes use glucose as energy?
If there is an excess of glucose
What does amino acid metabolism in the liver produce?
- Produces proteins for the liver and other tissues
- Produces hormones and nucleotides
What are the TCA intermediates used for in the liver?
- Gluconeogenesis: glucose enters circulation or is stored as glycogen
- Converts Pyruvate to Acetyl-CoA for liver cell energy
- Fatty acid synthesis
What does the liver store to produce hormones?
- Iron
- Vitamin A
What are the two sources of fatty acids?
- Diet
- Adipose tissue
Where are fatty acids sent to in the liver?
- Used for B-oxidation
- Released into the plasma as lipoproteins to adipose tissue
- Released in the form of free fatty acids in the blood (bound to albumin) –> fuel for muscles
What is Acetyl-CoA used for in lipid metabolism in the liver?
- Used to form ketone bodies in the blood (fuels heart and brain)
- Enters cholesterol synthesis (bile salts and steroid hormones)
- Enters the TCA cycle
Where is white adipose tissue found? Where is brown adipose tissue found?
- WAT: under skin, around major blood vessels (aorta) and abdomen
- BAT: under skin (chest and back)
How many lipid droplets are in WAT and BAT?
- WAT: one lipid droplet
- BAT: many lipid droplets
What provides the brown color in BAT? Who has BAT?
- Many mitochondria and high blood supply
- Children only
In which situation may an adult contain BAT?
Pre-adipocytes can differentiate into brown adipose tissue in adults during chronic cold exposure
What are the energy sources in WAT? BAT?
- WAT: glucose from glycolysis
- BAT: fatty acids from B-oxidation
Is WAT or BAT capable of fatty acid synthesis from excess glucose? Why?
- WAT
- Since it is insulin-sensitive