Chapter 19 Metabolic Integration

Question 1

Functions of the pancreas

Answer 1

Secretes insulin in response to rising blood glucose levels

Secretes digestive proteases that degrade dietary protein in the small intestine
- trypsin
- chymotrypsin
- elastase

Question 2

Functions of the small intestine

Answer 2

• absorbs nutrients
• secretes peptide hormones that control eating behaviors through neuronal signaling in the brain

Question 3

Functions of the large intestine

Answer 3

• absorb water and electrolytes

Question 4

What does ghrelin do?

Answer 4

the hunger hormone, stimulates appetite

Question 5

What does peptide YY do?

Answer 5

hormone that decreases appetite

Question 6

Functions of the stomach

Answer 6

• prepares food for small intestine by producing chyme, an acidic food slurry
• secretes peptide hormones that control eating behaviors through neuronal signaling in the brain

Question 7

Functions of the liver

Answer 7

• central processing facility and metabolic hub
• determines the dietary nutrients and metabolic fuels sent to peripheral tissues
• glucose regulator that removes excess glucose from blood when carbohydrate levels are high (controlled by insulin and glucagon signaling)
• portal vein directly delivers nutrients from the small intestine and inactivates toxins from the diet

Question 8

What are the metabolic fates of Glucose-6-phosphate?

Answer 8

Depends on the metabolic needs of the liver and peripheral tissue

• sent to pentose phosphate pathway
• used in glycogen synthesis
• converted to aceytl-CoA, which can go to lipid synthesis, ketone sythesis, or oxidative phosphorylation
• can be converted to glucose and released into the blood

Question 9

Functions of skeletal muscle

Answer 9

• uses fatty acids, glucose, or ketone bodies
• used in rapid bursts or endurance activities
• energy source during times of starvation
• stores glycogen

Question 10

Functions of cardiac muscle

Answer 10

• uses mostly fatty acids and ketone bodies
• uses aerobic respiration for energy

Question 11

What is creatine kinase?

Answer 11

A reversible enzyme that creates phosphocreatine when cellular ATP levels return to normal during muscle recovery

creatine kinase provides a phosphate from phosphocreatine to regenerate ATP from ADP

Question 12

Function of adipose tissues

Answer 12

• secretes peptide hormones (adipokines) to regulate metabolic homeostasis
• makes up 15%-25% of an individual’s mass
• fat is stored here

Question 13

Subcutaneous fat

Answer 13

• located in the thighs, buttocks, arms, and face

Question 14

Visceral fat

Answer 14

• located in the abdominal fat
• secretes adipokines
• more visceral fat gives rise to a higher risk of cardiovascular disease

Question 15

Body mass index

Answer 15

provides an estimation of total body fat in an average person

BMI = weight (kg)/height^2

Question 16

Functions of the brain

Answer 16

• control center of the body
• 20% of O2 consumed by the body is used for oxidative phosphorylation
• generally depends mostly on glucose (60% of body’s glucose is required by the brain)

Question 17

True or false, fatty acids can cross the blood brain barrier

Answer 17

false (but ketone bodies can)

Question 18

What is the blood brain barrierI (BBB)?

Answer 18

• BBB limits what molecules traverse into the brain substance
• blocks most molecules less than 500 daltons
• less restrictive at certain places

Question 19

What is PET imaging?

Answer 19

positron emission topography

uses metabolic radioactive 18F-deoxyglucose to show differences in glucose metabolism in the brain

Question 20

Function of kidneys

Answer 20

• utilizes gluconeogenesis
• removes concentrated levels of urea, NH4+, ketone bodies, and soluble metabolites

Question 21

What is hemodialysis?

Answer 21

When blood is filtered from a patient with poor kidneys in order to remove waste products before being returned to them.

Question 22

What is metabolic homeostasis?

Answer 22

The process of maintaining optimal metabolite concentrations and managing chemical energy reserves in tissues.

Question 23

Describe the triacylglycerol cycle

Answer 23

• An interorgan process that continually circulates fatty acids and triacylglycerols between adipose tissue and the liver
• maintains energy-rich fatty acids in circulation so that they can be used by peripheral tissues
• two components of that depend on sufficient levels of glycerol-3-phosphate: systemic and intracellular

Question 24

Describe the functions of insulin

Answer 24

• released by pancreatic beta cells
• stimulates glucose uptake in the liver, skeletal muscle, and adipose tissue
• activates glycogen and fatty acid synthesis
• decreases appetite through neuronal signaling in the brain

Question 25

Describe the functions of glucagon

Answer 25

• released by pancreatic alpha cells
• stimulates gluconeogenesis
• stimulates glycogen degradation
• stimulates fatty acid export from adipose tissue when food is not available

Question 26

What are islets of Langerhans?

Answer 26

structures in the pancreas that secrete digestive enzymes

Question 27

What is PPAR?

Answer 27

peroxisome proliferator-activated receptor

nuclear receptor proteins

Question 28

What do PPAR do?

Answer 28

• metabolic sensors of lipid homeostasis
• regulates gene expression in response to binding of low-affinity, fatty acid-derived nutrients
• important in energy metabolism and insulin sensitivity

Question 29

What occurs in the body during starvation?

Answer 29

Blood glucose levels are maintained by degradation of liver glycogen

Flux is altered in two ways:
- gluconeogenesis occurs
- fatty acids are used as fuels

Question 30

What does leptin do?

Answer 30

suppresses appetite, secreted by adipose tissue

Question 31

What are some potential effects of a lifelong positive energy balance?

Answer 31

• abdominal obesity
• insulin resistance
• hypertension
• hyperlipidemia
• high risk of cardiovascular disease

Question 32

Type I Diabetes

Answer 32

• insulin dependent
• insufficient insulin production by pancreatic beta cells

Question 33

Type II Diabetes

Answer 33

• insulin-resistant
• coupled to positive energy imbalance (weight gain)
• desensitization of insulin receptor signaling

Question 34

Describe the inflammation associated with obesity

Answer 34

TNF-alpha levels are high in adipocytes when lipid stores are high

TNF-alpha also downregulates adiponectin and fatty acid metabolism genes. It also inhibits insulin

Question 35

What are the four classes of diabetes treatment?

Answer 35

• alpha-glucosidase inhibitors; inhibits absorption of carbs
• sulfonylurea drugs; inhibit the pancreatic ATP-dependent K+ channel, increasing insulin secretion
• drugs that stimulate AMPK to increase glucose uptake and FA oxidation
• ligand agonists of the nuclear receptor PPAR gamma

Question 36

What three factors influence metabolic homeostasis?

Answer 36

• genetic inheritance
• nutrition
• exercise

Question 37

What does Ephedrine do?

Answer 37

Stimulates adrenergic receptor signaling through release of norepinephrine

Question 38

What does Lorcaserin do?

Answer 38

Appetite suppressant
Targets neuronal control of food consumption

Question 39

What does Orlistat do?

Answer 39

Pancreatic lipase inhibitor, prevents triglycerides from being metabolized with they pass through the digestive tract, allowing them to be excreted

Question 40

Describe good and bad fats

Answer 40

Saturated fatty acids and trans fats can increase LDL levels in blood

Polyunsaturated fatty acids and cis fats lower cardiovascular risk.

Question 41

What is the glycemic index?

Answer 41

A numerical value indicating how fast glucose is released into the blood after eating carb-rich foods relative to the rise in blood glucose levels after drinking a solution of pure glucose

glycemic index <55 are healthy carbs