Liver Physiology

Question 1

Is the rate of absorption of nutrients from the GIT constant?

Answer 1

no

Question 2

Digestion rate depends on what?

Answer 2

composition of food

Question 3

What is the pathway through which all fuels are converted from acetyl-CoA into carbon dioxide, water, and ATP?

Answer 3

Krebs cycle

Question 4

What are the metabolic fuels?

Answer 4

• glucose
• amino acids
• fatty acids
• ketone bodies

Question 5

What is the basic metabolic fuel that is essential for CNS?

Answer 5

glucose

Question 6

Glucose is stored as glycogen where?

Answer 6

• liver
• skeletal muscle

Question 7

What initiates oxidation of glucose?

Answer 7

glycolysis

Question 8

Each glucose yields what?

Answer 8

two pyruvates

Question 9

The two pyruvates yielded by glycolysis can enter what pathways?

Answer 9

Acetyl-CoA OR oxaloacetate

Question 10

Gluconeogensis occurs where?

Answer 10

in the liver and very small amount in kidneys

Question 11

What are the building blocks for proteins and substrates for gluconeogenesis?

Answer 11

amino acids

Question 12

Fatty acids are stored where as triglycerides?

Answer 12

adipose tissue

Question 13

Fatty acids can’t be converted to glucose, but can be converted to what?

Answer 13

ketone bodies

Question 14

What is derived from fat but is water soluble, can cross the BBB, and can provide energy to CNS during dietary energy deprivation?

Answer 14

ketone bodies

Question 15

What starts as a meal is ingested to ensure tissues are primed for arrival of glucose?

Answer 15

insulin secretion

Question 16

All glucose travels to the liver first via what?

Answer 16

portal vein

Question 17

Is glucose to fatty acid conversion reversible?

Answer 17

no

Question 18

Acetyl-CoA and oxaloacetate make up what?

Answer 18

citrate

Question 19

After fatty acids are formed from glucose, transfer to storage sites (adipose or muscle) is needed. Describe transport of fatty acids from liver.

Answer 19

• liver forms triglyceride-rich serum lipoproteins (specifically VLDLs)
• triglycerides transferred from chylomicrons and VLDLs to adipose tissue via lipoprotein lipase

Question 20

What are VLDLs?

Answer 20

very low density lipoproteins

Question 21

What are glucogenic amino acids?

Answer 21

amino acids that can be converted into glucose via gluconeogenesis

Question 22

What are ketogenic amino acids?

Answer 22

amino acids that can be converted into ketone bodies

Question 23

What amino acids are analogues in the portal vein?

Answer 23

• glutamate and alpha ketoglutarate
• alanine and pyruvate

Question 24

Glutamate and aspartate are removed by what from the portal vein?

Answer 24

enterocytes

Question 25

What proteins are synthesized in the liver?

Answer 25

most serum proteins such as albumin and blood clotting factors

Question 26

Most amino acids arriving in portal blood are deaminated in the liver and enter?

Answer 26

carbohydrate metabolism

Question 27

True carnivores have very little carbohydrate, so they must synthesize glucose from?

Answer 27

amino acids

Question 28

Ruminants use what to synthesize glucose?

Answer 28

propionate

Question 29

Fermentation in ruminants produces what?

Answer 29

volatile fatty acids (VFAs)

Question 30

True or false: most essential amino acids are not removed by the liver and go directly to periphery.

Answer 30

true

Question 31

Non essential amino acids can be synthesized where?

Answer 31

protein producing tissues

Question 32

Supply of amino acids to periphery and removal of amino acids by the liver can constantly be adjusted based on what?

Answer 32

dietary supply and needs

Question 33

Insulin promotes the uptake of glucose and amino acids by?

Answer 33

skeletal muscle

Question 34

When protein synthesis is greater than protein breakdown it leads to what?

Answer 34

increase in muscle size

Question 35

Overall, hepatic metabolism results in removal of what?

Answer 35

glucose and amino acids

Question 36

What are synthesized in the absorptive phase of amino acids?

Answer 36

protein and fat

Question 37

During the post-absorptive phase, nutrients will be mobilized from storage pools to maintain what?

Answer 37

energy availability

Question 38

Once blood glucose falls below normal, glucagon is released which stimulates what two enzymes in the liver?

Answer 38

- glycogen phosphatase - fructose 1,6 biphosphatase

Question 39

As blood glucose and insulin decrease, skeletal muscle starts to what?

Answer 39

mobilize amino acids

Question 40

What are the primary source of energy in muscle cells?

Answer 40

Branched chain amino acids (BCAAs)

Question 41

The liver has limited capacity for uptake of BCAAs, so conversion to what is necessary?

Answer 41

alanine

Question 42

In the liver, alanine is broken down into what?

Answer 42

urea and glucose

Question 43

A lack of insulin stimulates what in adipose tissue?

Answer 43

hormone sensitive lipase

Question 44

What can be used for energy by many tissues or taken up by the liver for ketone body production or VLDL synthesis?

Answer 44

non-esterified fatty acids (NEFAs)

Question 45

What enzyme releases fatty acids from adipose into blood where they then bind to albumin for transport and form non-esterified fatty acids (NEFAs)?

Answer 45

hormone sensitive lipase

Question 46

During fasting and starvation, utilization of adipose tissue stores spares what?

Answer 46

proteins

Question 47

During periods of prolonged undernutrition, fat is mobilized in the form of NEFAs for what?

Answer 47

- oxidized for energy - esterification to form triglycerides - production of ketone bodies

Question 48

In ruminants, _____ is precursor for glucose, enters Krebs cycle as ____, and forms _____.

Answer 48

- propionate - succinate - oxaloacetate

Question 49

Acetate and butyrate enter the Krebs cycle at which point?

Answer 49

Acetyl-CoA

Question 50

In ruminants, most fatty acids are made from what?

Answer 50

acetate

Question 51

In uncontrolled diabetes mellitus, a lack of insulin production leads to what?

Answer 51

glucagon production even though blood glucose is high

Question 52

In diabetes mellitus, what inhibits fatty acid synthesis, causing malonyl CoA to be low and CPT1 activity to be high which leads to ketone body production?

Answer 52

glucagon

Question 53

In diabetes mellitus, lack of insulin suppresses HSL, so blood NEFA is high or low?

Answer 53

high