Reg of Metabolism

8/3/2019 Reg of Metabolism

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Regulation of Metabolism

How does the body know when toincrease metabolism? Slow metabolism?

What might be some indicators of

energy status within the cell?

Requires communication

Works through allosteric

regulation of enzyme activity


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Figure 6-1 - Overview

Mechanisms of Cellular Communication


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Figure 6-2b


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Figure 6-2c


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Figure 6-2a


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What Hormones Regulate Metabolism?

Insulin

Glucagon

Thyroid hormone Cortisol

Epinephrine

Most regulation occurs in order to maintainstable blood glucose concentrations for

supplying fuel to the brain!


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Figure 6-3

Protein or peptidehormone

Almost always proteinscalled kinases

Activation/inactivation of anenzyme; opening/closing amembrane channel; activating atranscription factor


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Figure 6-4 (2 of 3)

Steroid Hormones

(examples: cortisol, testosterone, estrogen


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Figure 6-4 (3 of 3)

Protein/peptide hormones

(examples: epinephrine, insulin, glucagon, oxytocin)


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Figure 6-5


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Figure 6-7

Amplification

What are some advantages tohaving an amplified signal?

What might be somedisadvantages?


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Figure 6-8

How is the signal fromthe hormone (signalmolecule) binding to thereceptor transmittedinto the interior of thecell?


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Table 6-1


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Table 6-2


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Figure 6-10

Insulin works through a tyrosine kinase (TK) receptor mechanism

Insulin from F cells of the pancreas


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Figure taken from:http://www.smbs.buffalo.edu/bch/Courses/bch404/GW_Nature_InsulinSig.pdf#search=%22GLUT4%20vesicles%20micrograph%22

Insulin regulation of glucose entry in skeletal muscle

*Overall insulin promotes storage of glucose as a fuel and a reduction ofblood glucose when elevated


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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


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Figure taken from:

http://www.smbs.buffalo.edu/bch/Courses/bch404/GW_Nature_InsulinSig.pdf#search=%22GLUT4%20vesicles%20micrograph%22


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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 tostore excess energy


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Mechanism of action for glucagonGlucagon from E cells of pancreas


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Figure from:http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/glucagon.html

Major effects of glucagon:

Stimulates breakdown ofglycogen stored in the liver

Activates hepaticgluconeogenesis (using aminoacids and other non-carbohydrate precursors)

Overall the effects of glucagon are toincrease blood glucose when it is low


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Lactate from muscle

(Cori Cycle)

Glucogenic amino acids

Figure taken from: http://web.indstate.edu/thcme/mwking/gluconeogenesis.html


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Figure taken from:http://web.indstate.edu/thcme/mwking/gluco

neogenesis.html


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Thyroid releasing hormone/Thyroid stimulating hormone/Thyroid hormone

Hypothalamus Anterior pituitary Thyroid gland


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Figure taken from: http://www.nature.com/ncpendmet/journal/v1/n1/fig_tab/ncpendmet0020_F1.html

Increased metabolic rate and heat production

Increased fat mobilization

Increased carbohydrate metabolism


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Figure 6-15

Epinephrine works on cells via Ca2+ as a second messenger

Increasesglycogenolysis and

gluconeogenesis Increases release of

glucagon and cortisol


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Phosphorylation of glycogenphosphorylase; increasesbreakdown of glycogen in liver

Epinephrine can also work via the cAMP signaltransduction pathway


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Test Your Knowledge

The major hormones that promote glucose release into the bloodare:

The major hormones that promote storage of glucose are:

A hepatic cell has receptors for epinephrine, glucagon, andinsulin. These hormones may or may not act in concert toproduce a desired effect. How does the hepatocyte know whatto do?

What are the major second messenger systems used by thehormones that regulate blood glucose? What is the end resultof activation of these second messenger systems?


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Figure 6-14


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Figure 6-16


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Figure 6-17


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Table 6-3


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Table 6-5

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Reg of Metabolism