Metabolism Flashcards
Define calorie and calorimetry
Calorie - The amount of energy needed to raise a gram of water one degree C
Calorimetry - The measurement of heat energy released from the body via metabolism
The total energy required/expended equation
BMR + SDA + physical activity in = energy out
Another way to put it
Energy Out = External Work + Internal Work + Stored
What percent of energy expenditure is required for weight gain or loss to occur?
20%
How to calculate BMR from sample data?
Get BMR/hr from age/sex table
Draw line between height and weight to find SA
(SA)(BMR/hr)(24) = Daily Required Energy
What is the difference between direct and indirect calorimetry?
Direct Calorimetry - Measure of changes in temperature. In general, the more energy produces the greater the change
Indirect Calorimetry - Measure of oxygen consumed
Define BMR. How is it measured?
Basal Metabolic Rate - The rate of energy expended for the minimum amount of energy the body needs in a resting and fasting state
What are the standard conditions affecting BMR?
-No food ingested in last 12 hours
-subject mentally & physically relaxed (morning, prone, dark)
-Comfortable room temp
-No fever
Distinguish between endotherms and ectotherms
Endotherms maintain a stable body temp when thermoreceptors increase metabolism via hypothalamus-anterior pituitary-thyroid axis
Ectotherms get heat from environment
List the primary and secondary effects of thyroid hormones
Primary
-Stimulation of calorigenesis (heat production)
-Increase in catabolism/anabolism of proteins/lipids/carbs
-Increase oxygen consumption in most tissues
Secondary
-Increase respiratory rate
-Increase RBC count
-Promotes natural growth
-Promotes development/maturation of nervous system
Explain the hypothalamus-anterior pituitary-thyroid axis
Exterior Change in Temperature >
Heat receptors in skin signal Hypothalamus>
Hypothalamus releases TRH (Thyrotropin Releasing Hormone) >
Anterior Pituitary Gland release TSH (Thyroid Stimulating Hormone)>
Thyroid release T3 and T4 (Thyroxine and Triiodothyronine)>Target cells increase metabolism
What does thyroxine do to the BMR?
Increases it
What is a goiter?
An irregular growth of the thyroid
What are the symptoms of hypothyroidism?
Not enough thyroid hormone is produced, causing inability to tolerate cold, fatigue, constipation, depression, a slow heart rate, weight gain
How does the hypothalamus regulate the secretion of thyroxine and TSH?
It releases Thyrotropin Releasing Hormone to the anterior pituitary gland
