Revision week 1

Outline the roles played by the gastrointestinal tract and related organs in digestion and

absorption

Identify the key enzymes and hormones involved in digestion and absorption, and their

specific functions

1. List the structures of the GIT and their specific role in digestion and absorption.

2. What are 4 main regulatory hormones of the GIT, their signal and site of release, and their

function?

3. What are 8 main secretions of the GIT involved in digestion and absorption? Include their

respective role and site of secretion.

4. Briefly outline the digestive processes followed by a cheese and lettuce sandwich, including

relevant digestive secretions involved. What is the fate of these macronutrients after the

meal?

5. Describe the 4 main processes of absorption by which nutrients from food travel from the

lumen of the small intestine into enterocytes.

Passive diffusion: Moves down the [gradient], dependent on the [substrate]

Facilitated diffusion: Requires carrier protein, saturable, moves down the [gradient]

Active transport: Requires energy (ATP) and Na, e.g. Na/K ATPase. Can transport against the

[gradient]

Endocytosis: Engulfs a substance by surrounding it with cell membrane

6. The small intestine is the main site of absorption. Describe the structures of the small

intestine, including the absorption-related structures and how nutrients access the

circulation.

Three sections (duodenum, jejunum, ileum). Villi and microvilli on the intestinal wall ↑SA.

Hydrophilic nutrients access the circulation via the CV system via villi capillaries portal vein

liver and other organs/tissues

Lipophilic nutrients and large particles enters the lymphatic system (lymph vessels, nodes and

lymph) via villi lacteals lymphatic circulation thoracic duct blood circulation

7. Describe digestion and absorption, and illustrate these with a detailed example of each,

starting from consumption.

Digestion is the process of breaking down larger components (e.g. triglycerides) into smaller

particles (e.g. fatty acids and glycerol) via mechanical (e.g. emulsification by bile) and chemical

means (e.g. lipase). This is followed by the process of absorption, which refers to the the uptake of

nutrients (e.g. fatty acids) into the intestinal cells/enterocytes.

Week 2 energy metabolism

Illustrate how energy is extracted from energy yielding nutrients via metabolic pathways,

such as glycolysis, beta-oxidation, the citric acid cycle, and the electron transport system

Describe the role acetyl Co-A plays in energy metabolism

Identify the conditions that lead to ketogenesis and its importance in survival in fasting.

Describe the difference between ketosis and keto-acidosis

Describe the gluconeogenesis pathway and its role in the fasted state

Compare the fate of macronutrients for energy production in the fed and fasted states

1. What is energy metabolism? How is it regulated in the human body?

The entire network of chemical processes involved in

maintaining life, incl. biochemical reactions that enable

us to release and utilise energy from macronutrients

and to synthesise substance from another and prepare

waste products for excretion. It is regulated by two

distinct pathways: anabolic and catabolic pathways:

2. Explain what happens to energy metabolism in type 1 diabetes patients, and what the

consequences are if type 1 diabetes is not controlled.