Digestion and Metabolism 4

Flashcards covering key concepts of metabolism, including anabolic/catabolic reactions, cellular respiration pathways, digestion and absorption of macronutrients, lipogenesis, ketogenesis, protein metabolism, and the absorptive and postabsorptive states.

What are the two main types of reactions involved in metabolism?

Anabolic and Catabolic reactions.

What is the primary product of glycolysis in the cytosol?

Pyruvic Acid (pyruvate).

Under what condition does the anaerobic pathway occur if O2 is unavailable?

If oxygen is unavailable.

What is the end product of the lactic acid pathway during anaerobic respiration?

Lactic Acid.

Where does the aerobic pathway of cellular respiration occur?

In the mitochondria.

What is the total approximate ATP produced from the aerobic pathway of a single glucose molecule?

Approximately 36-38 ATP.

What are the common reasons for anaerobic respiration (incomplete glucose oxidation)?

Lack of O2, non-functional mitochondria, or lack of mitochondria (e.g., red blood cells).

What are the absorbable units of dietary protein, carbohydrate, and fat after digestion?

Amino acids, Glucose, and Fatty acids/Monoglycerides, respectively.

What is the process of building lipids from glycerol and fatty acids called?

Lipogenesis.

Where does lipogenesis primarily occur?

In adipose (fat) tissue and the liver.

What happens to excess glucose after it undergoes glycolysis and pyruvate oxidation?

It can be converted into excess Acetyl CoA, leading to the synthesis of fatty acids, triglycerides, cholesterol, steroid hormones, and bile.

Which type of metabolism, fatty acid (14 carbons) or glucose, produces more ATP?

Fatty acid metabolism (approx. 114 ATP for 14 carbons vs. approx. 36 ATP for glucose).

What is ketogenesis, and what are its products?

Ketogenesis is the process where excess Acetyl CoA from beta-oxidation of fatty acids is converted into ketones and CO2.

What is a potential consequence of too many ketones accumulating in the blood?

Metabolic acidosis.

What are the main products of protein digestion?

Amino acids, di-peptides, and tri-peptides.

What happens to excess amino acids in the liver?

They undergo deamination, converting ammonia to urea, which is then excreted by the kidneys.

What defines the 'Absorptive State' for the body?

When the body is actively absorbing nutrients (also known as the 'Fed State').

During the absorptive state, what happens to blood glucose and plasma amino acid levels, and what hormone is released in response?

Both blood glucose and plasma amino acid levels increase, causing the release of insulin from pancreatic beta cells.

What are the main actions of insulin on target tissues during the absorptive state?

Insulin increases glycogenesis, stimulates glucose and protein uptake by body cells, converts excess glucose to glycogen, synthesizes actin/myosin from amino acids, and stores excess lipids in adipose cells.

What defines the 'Postabsorptive State' for the body?

When there is no food intake and the body is not actively absorbing nutrients (also known as the 'Fasted State').

During the postabsorptive state, what happens to blood glucose levels, and what hormone is released?

Blood glucose levels fall, causing the release of glucagon from pancreatic alpha cells.

What are the main actions of glucagon during the postabsorptive state?

Glucagon stimulates glycogenolysis (breakdown of glycogen to glucose), gluconeogenesis (conversion of non-carbs to glucose), and the release of stored lipids from adipose cells.