Zaidi- Integration of Metabolism Flashcards
What is (GLP-1)?
Glucagon like peptide-1. Secreted by L cells in the intestine. Induce feelings of satiety in brain. Potentiates insulin action in pancreas. Potentiates glucose-induced insulin secretion by B cells of pancreas while inhibiting glucagon secretion.
What is cholecystokinin?
CCK. Secreted by small intestine in response to a meal. Induce feelings of satiety in brain. Potentiates insulin action in pancreas. Helps in digestion, stimulating secretion of pancreatic enzymes & bile salts from gallbladder
What is ghrelin?
Appetite enhancer. Peptide secreted by stomach, acts on regions of the hypothalamus to stimulate appetite through its receptor (GPCR)
What is leptin?
Hormone secreted by adipocytes (reports the status of TAG stores). More fat=more leptin
What is insulin?
Secreted by B cells of pancreas (reports on status of blood glucose)
What are SOCS?
Suppressors of Cytokine Signaling
-Inhibit receptor action by: binding to receptor, binding to other components of signaling pathway, enhancing proteolytic degradation of receptor
What happened to the SOCS knockout mice?
Displayed enhanced sensitivity to leptin & were resistant to weight gain, even on a high fat diet
What does adipose tissue do?
Degrades TAGs & releases fatty acids & glycerol
What does the heart muscle consume for energy in preference to glucose?
Acetoacetate
What can lead to tissue death (myocardial infarction)?
Blockage of circulation & lack of O2
How does skeletal muscle get energy?
Rich in glycogen, glycogen readily broken down to G6P. Lacks glucose 6-phosphatase so muscle retains glucose, its preferred fuel for bursts of activity. Also uses fatty acids & ketone bodies for energy
What happens in the initial states of prolonged fasting?
Proteins are degraded & the carbon skeletons are used as gluconeogenic precursors?
How does calcium alter the cell’s biochemistry?
Can act as a second messenger to activate signaling pathways. These generate nuclear transcription factors that stimulate the expression of specific genes that stimulate mitochondrial biogenesis
How do cells sense low cellular ATP levels?
Via the serine/threonine kinase AMP-activated protein kinase (AMPK) complex. Under conditions of low energy, AMPK phosphorylates multiple enzymes & growth control nodes. Act leads to decrease in anabolic pathways & increase in catabolic pathways. The competition between ATP & AMP for binding to AMPK allosteric sites determines its activity
- inact. by ATP
- act by AMP
What are the three components of AMPK?
Catalytic alpha subunit that carries the protein kinase activity and regulatory beta and gamma subunits
