Metabolism Module Lecture 1

Questions and Answers

What is the primary function of metabolism?

To derive energy and raw materials from food and use them to support repair, growth, and activity of tissues.

Which of the following is a form of energy work performed by cells?

Biosynthetic

Transport

Mechanical

All of the above (correct)

What are the two main processes of metabolism?

Absorption and Assimilation

Catabolism and Anabolism (correct)

Digestion and Excretion

Oxidation and Reduction

Match the nutrients with their description:

Carbohydrates = General source of energy Proteins = Building blocks for growth Lipids = Storage of energy Vitamins = Essential for biochemical reactions Signup and view all the answers

Energy intake exceeding expenditure will lead to a decrease in body weight.

False Signup and view all the answers

What are exergonic reactions?

Reactions where more energy is released than used. Signup and view all the answers

What is the role of the ATP/ADP cycle in metabolism?

It couples the energy released by exergonic reactions to that needed for endergonic reactions. Signup and view all the answers

What is the concentration of glucose in fasting blood plasma?

5 mmol.l-1 Signup and view all the answers

What happens to energy stores if expenditure exceeds intake?

Energy stores will deplete, followed by the utilization of other body components, primarily protein. Signup and view all the answers

Study Notes

Overview of Nutrient Metabolism

Metabolism involves processes that derive energy and raw materials from food, supporting repair, growth, and activity of body tissues.
Essential components of nutrient metabolism include the roles of the gastrointestinal tract (GIT), blood, and tissues in nutrient conversion, storage, utilization, and waste elimination.

Metabolic Energy

All living organisms utilize energy to combat entropy, support growth, repair cells, and maintain body temperature in endothermic species (e.g., mammals and birds).
Energy types used by cells include biosynthetic, transport, mechanical, and electrical work.

Raw Materials and Nutritional Requirements

Body constituents are produced from basic materials sourced from the diet, necessitating essential nutrients that undergo interconversion through energy expenditure.

Metabolic Processes

Two main metabolic processes:
- Catabolism: The breakdown of large molecules into smaller ones to release energy.
- Anabolism: The use of energy to synthesize molecules necessary for growth and maintenance.

Chemical Bond Energy

Chemical reactions involve the breaking and formation of chemical bonds, with exergonic reactions releasing more energy than they consume and endergonic reactions requiring more energy than they produce.

Coupling and the ATP-ADP Cycle

Metabolic processes couple the energy released from exergonic reactions to the energy required for endergonic reactions through an intermediate process, notably the ADP/ATP cycle.

Nutritional Intake

Average food consumption is approximately 500 kg per year, providing energy, building blocks (amino acids, carbohydrates, lipids), specific nutrients (vitamins, minerals), water, and fibers.

Blood as a Transport Medium

Blood carries nutrients from the diet to tissues for utilization, storage, interconversion, and transports produced materials and waste products for excretion.

Blood Concentrations and Nutrient Regulation

The concentration of substances in blood is maintained at constant levels despite fluctuating nutrient supply and variable demand, with tissues capable of nutrient storage and interconversion.

Kidneys: No storage, can interconvert and utilize nutrients.
Liver: Stores, interconverts, and utilizes nutrients.
Adipose tissue: Stores but does not interconvert, utilizes nutrients.
Skeletal muscle, heart muscle, brain: Primarily utilize nutrients without storage or interconversion.

Fasting Blood Plasma Composition

Typical concentrations during fasting include:
- Glucose: 5 mmol/l
- Amino acids: 2 mmol/l
- Triacylglycerol: 2 mmol/l
- Cholesterol: 5 mmol/l
- Fatty acids: 0.5 mmol/l
- Lactate and pyruvate: Found in 97% of the population.

Energy Balance and Body Weight

Body weight remains stable when energy intake matches expenditure.
If energy intake exceeds expenditure, body weight increases due to energy storage.
When expenditure exceeds intake, energy reserves are depleted first, followed by the utilization of body components primarily composed of protein for energy.

Body Composition Insights

Illustrates differences in body composition based on weight, emphasizing importance of carbohydrate, protein, and fat in overall body structure and health.

Description

Explore the foundational concepts of metabolism with Dr. Lina Yousif Mohammed in this first session. Topics include nutrient metabolism, metabolic energy, rates, and nutritional requirements. This lecture sets the stage for further understanding in the Metabolism Module.