Hormonal Control of Metabolism

Question 1

Lipid metabolism from 1000 ft

Answer 1

Question 2

Insulin vs cortisol on protein metabolism

Answer 2

Question 3

Why does the brain need to be able to function on ketone bodies as well as glucose?

Answer 3

In starvation, glucose is the first to go, and there is no way to convert fatty acids into glucose in the human body. Instead, ketone bodies serve as a mechanism to transport energy from fatty acids to the brain to maintain brain function.

Question 4

Pancreatic Islets

Answer 4

Question 5

Important differences between energy storage lipids and membrane lipids

Answer 5

Energy storage: Mostly triacylglycerols, which are of neutral charge. Exclusively utilize palmitic acid.

Membrane lipids: Mostly contain a phosphate group coupled to an alcohol, making them negatively charged. Utilize various fatty acids including unsaturated fatty acids.

Question 6

If insulin falls low, ___ slows or stops in skeletal muscle cells. If it falls too low, skeletal myocytes will _____.

Answer 6

If insulin falls low, muscle production slows or stops in skeletal muscle cells. If it falls too low, skeletal myocytes will degrade their own protein to release it into the blood.

Utimately these amino acids would then be utilized to synthesize glucose for the brain.

Question 7

Humans do not posess a mechanism to go from ____ to ____. Only in the reverse direction.

Answer 7

Humans do not posess a mechanism to go from Acetyl-CoA to Pyruvate. Only in the reverse direction (Pyruvate dehydrogenase).

You cannot make glucose from fatty acids!!!!

Question 8

Carbohydrate metabolism from 1000 ft

Answer 8

Question 9

Fundamental links between carbodydrate, amino acid, and lipid metabolism

Answer 9

Question 10

Regulation of glucagon release from alpha cells

Answer 10

Insulin!!!! You never have high insulin and high glucagon unless something has gone very wrong.

High levels of circulating amino acids stimulate release of glucagon, as does epinephrine (sympathetic nervous system activation).

Question 11

Beta islet insulin release diagram

Answer 11

Question 12

Insulin and glucagon sensing

Answer 12

Question 13

84-95% of human fuel storage is in the form of ___.

Answer 13

84-95% of human fuel storage is in the form of fat.

Question 14

Where metabolism takes place in the cell

Answer 14

Question 15

Lipoprotein traffic

Answer 15

Question 16

Pyruvate dehydrogenase must be irreversible in order to ____.

Answer 16

Pyruvate dehydrogenase must be irreversible in order to commit methyl groups on Acetyl-CoA to the citric acid cycle.

Question 17

The carbon skeleton of alanine is the same as that for ____.

Answer 17

The carbon skeleton of alanine is the same as that for pyruvate.

Pyruvate is made from alanine via the action of alanine transaminase. The amino group for this reaction is given to α-ketoglutarate to form L-glutamate. This reaction also requires pyridoxal phosphate (PLP, aka vitamin B₆) as a coenzyme.

Question 18

Insulin signaling via RTKs

Answer 18

Question 19

Glucagon/Epinephrine-regulated metabolism at 1000 ft

Answer 19

Question 20

Various outputs of Akt

Answer 20

Question 21

In addition to glucagon, ____ also helps stimulate glucose production and release

Answer 21

In addition to glucagon, epinephrine also helps stimulate glucose producUon and release

Question 22

Amino acid metabolism from 1000 ft

Answer 22

Question 23

Insulin-regulated metabolism at 1000 ft

Answer 23

Question 24

Key pathways of amino acid metabolism

Answer 24

Question 25

Major lipases in lipid transport regulation

Answer 25

**Hormone-sensitive lipase** is expressed in **adipocytes** in response to **glucagon or epinephrine** and triggers **release of triacylglycerides** by adipocytes. **Lipoprotein lipase** is expressed in **capillaries** in response to **insulin** and triggers the **conversion of circulating lipoprotein particles** (**chylomicrons and VLDL**) **into fatty acids** to allow **bordering adipocytes** to **absorb** the fatty acids.

Question 26

How do beta islet cells sense glucose?

Answer 26

Glut2 transports glucose into the cell and enables ATP generation via oxidative phosphorylation. **In beta islet cells, ATP inhibits an ATP-gated K⁺ channel.** Closing this channel causes **depolarization** of the membrane**,** leading to **Voltage-gated Ca²⁺** channel opening and **calcium-mediated vescile fusion** and **insulin release.**

Question 27

Dietary fat ingestion

Answer 27

Question 28

Male and Female body fat percentages

Answer 28

Male: 18-24% Female: 25-31% Over these ranges is considered clinically obese.

Question 29

Phosphorylation by ___ activates hormone-sensitive lipase

Answer 29

Phosphorylation by **PKA** activates hormone-sensitive lipase

Question 30

Unlike carbohydrates and lipids, protein serves an additional role as _____ and thus overutilization has functional consequences.

Answer 30

Unlike carbohydrates and lipids, protein serves an additional role as **a building block in both mitotic and post-mitotic cells** and thus overutilization has functional consequences. Especially on skeletal muscle

Question 31

How fat cells release fatty acids

Answer 31

Question 32

Fuel homeostasis following meal

Answer 32

Question 33

Cortisol activates the expression of genes that promote ___ breakdown.

Answer 33

Cortisol activates the expression of genes that promote **skeletal muscle** breakdown. These include E3 ubiquitin ligases that recognize sacromere components.