Transcript Regulation of Metabolism

Regulation of Metabolism
• How does the body know when to
increase metabolism? Slow metabolism?
Requires communication
• What might be some indicators of
energy status within the cell?
Works through allosteric
regulation of enzyme activity
Mechanisms of Cellular Communication
Figure 6-1 - Overview
Figure 6-2b
Figure 6-2c
Figure 6-2a
What Hormones Regulate Metabolism?
• Insulin
• Glucagon
• Thyroid hormone
• Cortisol
• Epinephrine
Most regulation occurs in order to maintain
stable blood glucose concentrations for
supplying fuel to the brain!
Protein or peptide
hormone
Almost always proteins
called kinases
Activation/inactivation of an
enzyme; opening/closing a
membrane channel; activating a
transcription factor
Figure 6-3
Steroid Hormones
(examples: cortisol, testosterone, estrogen
Figure 6-4 (2 of 3)
Protein/peptide hormones
(examples: epinephrine, insulin, glucagon, oxytocin)
Figure 6-4 (3 of 3)
Figure 6-5
Amplification
What are some advantages to
having an amplified signal?
What might be some
disadvantages?
Figure 6-7
How is the signal from
the hormone (signal
molecule) binding to the
receptor transmitted
into the interior of the
cell?
Figure 6-8
Table 6-1
Table 6-2
Insulin works through a tyrosine kinase (TK) receptor mechanism
Insulin from b cells of the pancreas
Figure 6-10
Insulin regulation of glucose entry in skeletal muscle
*Overall insulin promotes storage of glucose as a fuel and a reduction of
blood glucose when elevated
Figure taken from:
http://www.smbs.buffalo.edu/bch/Courses/bch404/GW_Nature_InsulinSig.pd
f#search=%22GLUT4%20vesicles%20micrograph%22
Insulin regulation of glucose metabolism in the liver
Figure taken from:
http://www.smbs.buffalo.edu/bch/Courses/bch404/GW_Nature_InsulinSig.pdf#search=%22GLUT4%20vesicles%
20micrograph%22
Figure taken from:
http://www.smbs.buffalo.edu/bch/Courses/bch404/GW_Nature_InsulinSig.pdf#search=
%22GLUT4%20vesicles%20micrograph%22
Major Effects of Insulin
• Skeletal muscle takes up glucose from blood
• Liver takes up glucose, increases glycogen production
• Liver increases fatty acid synthesis when its glycogen
stores are full
• Adipose takes up blood glucose and fatty acid
breakdown is inhibited
Overall insulin has a fat sparing action. It works to
store excess energy
Mechanism of action for glucagon
Glucagon from a cells of pancreas
Figure 6-11 - Overview
Major effects of glucagon:
• Stimulates breakdown of
glycogen stored in the liver
• Activates hepatic
gluconeogenesis (using amino
acids and other noncarbohydrate precursors)
Overall the effects of glucagon are to
increase blood glucose when it is low
Figure from:
http://www.vivo.colostate.edu/hbooks/pathphys/endo
crine/pancreas/glucagon.html
Glucogenic amino acids
Lactate from muscle
(Cori Cycle)
Figure taken from: http://web.indstate.edu/thcme/mwking/gluconeogenesis.html
Figure taken from:
http://web.indstate.edu/thcme/mwking/gluco
neogenesis.html
Thyroid releasing hormone/Thyroid stimulating hormone/Thyroid hormone
Hypothalamus
Anterior pituitary
Thyroid gland
Figure 6-12 - Overview
• Increased metabolic rate and heat production
• Increased fat mobilization
• Increased carbohydrate metabolism
Figure taken from: http://www.nature.com/ncpendmet/journal/v1/n1/fig_tab/ncpendmet0020_F1.html
Epinephrine works on cells via Ca2+ as a second messenger
• Increases
glycogenolysis and
gluconeogenesis
• Increases release of
glucagon and cortisol
Figure 6-15
Epinephrine can also work via the cAMP signal
transduction pathway
Phosphorylation of glycogen
phosphorylase; increases
breakdown of glycogen in liver
Test Your Knowledge
• The major hormones that promote glucose release into the blood
are:
• The major hormones that promote storage of glucose are:
• A hepatic cell has receptors for epinephrine, glucagon, and
insulin. These hormones may or may not act in concert to
produce a desired effect. How does the hepatocyte know what
to do?
• What are the major second messenger systems used by the
hormones that regulate blood glucose? What is the end result
of activation of these second messenger systems?
Figure 6-14
Figure 6-16
Figure 6-17
Table 6-3
Table 6-5