Phase 1A Rajpinder Singh Seehra The Peer Teaching Society is not liable for false or misleading information… IMMS 2- Metabolism.

Phase 1A

Rajpinder Singh Seehra

The Peer Teaching Society is not liable for false or misleading information…

IMMS 2- Metabolism

• Metabolism (definition)• Metabolic Rate and Influencing Factors• Fuel types and their Effectiveness• Storing Energy


Aims

• Metabolism: chemical reactions that occur in a living organism.

• Metabolic rate: total-body energy expenditure per unit time.

• Total Energy Expenditure: internal heat produced + external work performed+ energy stored.

(Vander’s Human Physiology 12th Edition)


Definitions

• The metabolic rate when a person is at mental and physical rest but not sleeping, at comfortable temperature and has fasted at least 12 hours.

• 60% of the total energy expenditure


Basal Metabolic Rate (BMR)

• Sleep (↓ when asleep) • Age (↓ with ↑ age)• Gender (women<men)• Fasting (BMR ↓ to conserve energy stores)• Height, Weight• Pregnancy


Factors Affecting the Metabolic Rate

• An important organ in regulating metabolic control.

• Functions include:• control of the autonomic nervous system (ANS)• regulation of food intake (thirst and feeding

centres)• regulation of body temperature

• Very important factor in metabolic disorders.


The Hypothalamus

• Endocrine organ.• Located in the neck, two connected lobes.• Controls how quickly the body:

• uses energy• makes protein• and hormone sensitivity

• Produces thyroid hormones T3 and T4 to do the above functions.

• Regulated by thyroid-stimulating hormone from the anterior pituitary which in turn is controlled by thyrotropin=releasing hormone from the hypothalamus.


The Thyroid

• Body Temperature Regulation• Infection and disease• Food intake• Exercise —> any form of muscular activity*• Stress• Hormone levels (adrenaline, thyroid hormone)


Factors Affecting Daily Energy Expenditure

• Carbohydrate: Used in the form of glucose. 30% of ATP production at rest.

• Fat: Can be in the form of triglycerides or esterified fatty acids. 70% of ATP production at rest.

• Protein: last used, often due to longer periods of starvation. Stores seem to decrease with age.


Fuel Types and their Effectiveness

• Carbohydrate: 1g converts to approximately 17 joules of energy

• Fat: 1g converts to approximately 38 joules of energy

• Protein: 1g converts to approximately 17 joules of energy


Fuel Types and their Effectiveness

• Alcohol.• Converted from:

• ethanol to acetaldehyde (alcohol dehydrogenase IB, a hepatic enzyme)

• acetaldehyde to acetic acid (aldehyde dehydrogenase 2)• acetic acid to acetyl-CoA (acetyl CoA synthase-1 and 2)• acetyl-CoA to water and carbon dioxide. (CAC)

• When alcohol is in excess the effects become more predominant and thus a greater period of time is required to clear the system.


Ethanol

• To keep body weight stable: Energy used=energy intake

• Energy stored is therefore: intake - expenditure• If this is positive the body works to store the

excess energy.• Generally an anabolic process (synthesis a larger

molecule from smaller components)


Storing Energy

• Account for 1 percent of body mass.• Glycogenesis: conversion of excess glucose into

glycogen as a cellular storage mechanism.• Stored as glycogen in skeletal muscle and the liver.• Excess is often catabolised to form Acetly-CoA• Insulin acts to increase the storage process and

insulin levels correlate to blood glucose.


Carbohydrate Storage

• Account for 15 percent of body mass.• Primarily stored as triglycerides (ester of glycerol

and 3 fatty acids).• Fatty acids are converted to triglycerides for

storage.• Mainly stored in adipocytes.


Lipid Storage

• Account for 17 percent of body mass.• Stored in muscle.• Amino acids built into relevant proteins for the

cell functions.


Protein Storage


Any Questions?

Phase 1A Rajpinder Singh Seehra The Peer Teaching Society is not liable for false or misleading information… IMMS 2- Metabolism.

Documents

misleading information

misleading information

jthe metabolic rate

totalbody energy expenditure

form of triglycerides

form of glucose

physical rest

atp production