Transcript Metabolism

Memmler’s
The Human Body in Health and Disease
11th edition
Chapter 20
Metabolism, Nutrition and Body
Temperature
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Metabolism
Two categories
• Catabolism
– Breakdown complex compounds into simpler
compounds
• Anabolism
– Building simple compounds into needed substances
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-1: What are the two phases of
metabolism?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cellular Respiration
• Energy released from nutrients in a series of reactions
• Early studies done with glucose as starting compound
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Cellular respiration. This
diagram shows the
catabolism of glucose
without oxygen (anaerobic)
and with oxygen (aerobic).
(C = carbon atoms in one
molecule of a substance.) In
cellular respiration, glucose
first yields two molecules of
pyruvic acid, which will
convert to lactic acid under
anaerobic conditions, as
during intense exercise.
(Lactic acid must eventually
be converted back to
pyruvic acid.) Typically,
however, pyruvic acid is
broken down aerobically
(using oxygen) to CO2 and
H2O (aerobically).
Zooming In: What does
pyruvic acid produce in
cellular respiration under
anaerobic conditions? Under
aerobic conditions?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Anaerobic Phase
• Occurs in cytoplasm
• Yields 2 ATP molecules per glucose molecule
• Product is pyruvic acid
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Aerobic Phase
• Occurs in mitochondria
• Yields 34-36 ATP molecules per glucose molecule
• Product is carbon dioxide and water
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-2: What name is given to the
series of cellular reactions that releases energy
from nutrients?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question:
Where does the anaerobic phase of
glucose breakdown take place in the
cell?
a. in the cytoplasm
b. in the mitochondria
c. in the nucleus
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
a. in the cytoplasm
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Metabolic Rate
• Rate at which energy is released from nutrients in cells
• Decreases with age
• Measured in kilocalories (kcal)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Use of Nutrients for Energy
• Glucose is main source of energy
– Reserves stored in liver and muscle cells as glycogen
• Other energy sources
– Glycerol
– Fatty acids
– Amino acids
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-3: What is the main energy
source for cells?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Anabolism
• Essential nutrients
– Cannot be made by body
– Must be taken in diet
• Essential amino acids
– Nine of 22 must be eaten
• Essential fatty acids
– Linoleic acid and linolenic acid
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-4: What is meant when an
amino acid or a fatty acid is described as
essential?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question:
True or False?: The breakdown phase
of metabolism is catabolism.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
True: The breakdown phase of
metabolism is catabolism.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Minerals and Vitamins
• Minerals are chemical elements
– Body structure
– Fluid balance
– Muscle contraction
– Nerve impulse conduction
– Blood clotting
• Vitamins are complex substances
– Water soluble
– Fat soluble
• Antioxidants
– Stabilize free radicals
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-5: Both vitamins and minerals
are needed in metabolism. What is the
difference between vitamins and minerals?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nutritional Guidelines
• Percentage of calories in daily diet
• Carbohydrate: 55 – 50%
• Fat: 30% or less
• Protein: 15 – 20%
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Carbohydrates
Diet should be mainly complex, naturally occurring
carbohydrates
• Normal blood glucose range 85 to 125 mg/dL
• Glycemic effect measures how rapidly food raises blood
glucose level, stimulates release of insulin
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-6: What is the normal range
of blood glucose?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Fats
• Saturated
– Most are from animal sources
– Solid at room temperature
• Unsaturated
– Derived from plants
– Liquid at room temperature
• Hydrogenated
– Artificially saturated
– Trans-fatty acids
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Proteins
• Not stored in body
• Most animal proteins supply all essential amino acids
• Most vegetable proteins lack one or more essential amino
acids
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Vitamin and Mineral Supplements
• Supplements are controversial
• Some populations may benefit
• Some vitamins cause toxic effects when taken in excess
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question:
What is the recommended
percentage of daily calories that
should come from fats?
a. 15%
b. 30%
c. 55%
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
b. 30%
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Food Guide Pyramid
• United States Department of Agriculture publishing guidelines since
1916
• Newest version is 2005 Food Guide Pyramid
• Represents quantities of food recommended each day for good health
• 2006 is first version to include physical exercise as a component of a
healthy diet.
• Other updates in 2006:
–
Stresses variety in the diet
–
Stresses moderation
–
Stresses eating fruits and vegetables
–
Includes choices of “nutrient-dense” foods
–
Does not include sugar, solid fats, or alcohol; termed
“discretionary calories”
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The 2006 Food Guide Pyramid
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Alcohol
• Not a nutrient
• Interferes with metabolism
• Should be consumed in moderation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-7: What are typical
recommendations for the relative amounts of
carbohydrates, fats, and proteins in the diet?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nutritional Disorders
• Excess of nutrients
• Shortage of nutrients
• Weight control
• Food allergies
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Food Allergies
• Allergens can be food or food additives
• Allergic reactions involve
– Skin
– Respiratory tract
– Gastrointestinal tract
• Reactions can be fatal
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Malnutrition
Can occur from missing nutrients or too much of wrong
foods
• Protein and energy malnutrition (PEM)
• Marasmus
• Kwashiorkor
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Overweight and Obesity
• Causes are complex
• Incidence is increasing
• Shortens life span
• Measured by body mass index (BMI)
– Overweight is BMI of 25 – 30
– Obese is BMI greater than 30
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Underweight
• Low reserves of energy
• Reproductive disturbances
• Nutritional deficiencies
• BMI less than 18.5
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question:
Ms. L. has a BMI score of 18;
therefore she is:
a. obese
b. slightly overweight
c. underweight
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
c. underweight (BMI score <18.5)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nutrition and Aging
• Nutritional deficiencies may develop
• Medications may interfere with appetite and absorption
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Body Temperature
• Heat is byproduct of chemical activities in body tissues
• Regulatory devices keep body temperature constant
within narrow limits
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Heat Production
Amount of heat produced by organs affected by
• Exercise
• Hormone production
• Food intake
• Age
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-8: What are some factors that
affect heat production in the body?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Heat Loss
• More than 80% of heat loss occurs through skin
– Conduction
– Radiation
– Convection
– Evaporation
• 15-20% heat loss through respiration and elimination
• Heat loss prevention
– Clothing
– Fat layer under skin
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Temperature Regulation
Body has internal mechanisms for regulating temperature
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Role of the Hypothalamus
Regulation of
• Heat loss
– Constrict skin blood vessels
– Shiver
– Increase cell metabolism
• Overheating
– Stimulate sweat glands
– Dilate skin blood vessels
– Muscle relaxation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-9: What part of the brain is
responsible for regulating body temperature?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Age Factors
• Newborns and elderly
• Reduced ability to produce heat
• Reduced ability to regulate overheating
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Normal Body Temperature
• Normal range is 36.3ºC to 37.6ºC (97.8ºF to 100.8ºF)
• Varies with time of day
• Varies by body part
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-10: What is normal body
temperature?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Fever
• Higher than normal body temperature
• Causes
–
Infection
–
Malignancies
–
Brain injuries
–
Toxic reactions
–
Vaccine reactions
–
Central nervous system diseases
• Crisis
• Lysis
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Responses to Excessive Heat
• Heat cramps
– Localized muscle cramping
• Heat exhaustion
– Heat retention and fluid loss
• Heat stroke
– Medical emergency that can be fatal
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-11: What are some conditions
brought on by excessive heat?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question:
Which of the following is NOT one of
the 4 processes by which body heat
is lost?
a. radiation
b. circumduction
c. evaporation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer:
b. circumduction
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Responses to Excessive Cold
• Hypothermia
– Excessively low body temperature
– Used in some types of surgery
• Frostbite
– Can cause permanent local tissue damage
– Likely areas are face, ears, extremities
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Checkpoint 20-12: What is the term for
excessively low body temperature?
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
End of Presentation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins