chapter 17 Flashcards
Metabolism
total of all reactions that take place within the body
Body temperature
Normal Range
human body temp- 96.5 to 99.5
oral temp- 98.6
fluctuates 1-2 degrees during the day with lowest occurring while asleep
Thyroxine
The most important regulator of day-to-day metabolism; increases use of foods for ATP production, thereby increasing heat production
Epinephrine and sympathetic stimulation
Important in stress situations; increases the metabolic activity of many organs; increases ATP and heat production
Skeletal Muscles
Normal muscle tone requires ATP; the heat produced is about 25% of the total body heat at rest
Liver
Always metabolically active; produces as much as 20% of the total body heat at rest
Food intake
increases activity of the GI tract; increases ATP and heat production
Higher body temperature
Increases metabolic rate, which increases heat production, which further increases metabolic rate and hear production; maybe become detrimental during high fever
Radiation
means that heat from the body is transferred to cooler objects not touching the skin
Conduction
The loss of heat to cooler air or objects such as clothing, that touch the skin
Convection
air currents move the warmer air away from the skin surface and facilitate the loss of heat
Ex:fan
Vasoconstriction
decreases blood flow through the dermis and thereby decreases heat loss
Ex:Shivering
Vasodilation
blood flow to dermis increases and heat loss increases
ex:sweating
Eccrine sweat glands
secrete sweat onto the skin surface and excess body heat evaporates the sweat
requires loss of water, which can lead to dehydration
Skin (major pathway) heat loss
Radiation and conduction- heat is loss from the body to cooler air or objects
Convection- air currents move warm air away from the skin
Sweating-excess body body heat evaporates sweat on the skin surface
Respiratory tract (secondary pathway) heat loss
Evaporation-body heat evaporates water from the respiratory mucosa, and water vapor is exhaled
Urinary tract (minor pathway)
Urination- urine is at body temperature when eliminated
Digestive tract (minor pathway)
Defecation- feces are at body temperature when eliminated
Hypothalamus
responsible for regulation of body temperature and is considered the “thermostat” of the bod
above 106 degrees hypothalamus begins to lose its ability to regulate temperature
Fever
Abnormally high body temperature
Pyrogens are substances that cause fevers
Pyrogens affect the hypothalamus
May be beneficial if moderately elevated
Anabolism
Building up of smaller molecules into larger ones
Catabolism
decomposition of the bonds of larger molecules to form smaller molecules
Cell Respiration
Co2- waste product that is exhaled
H20- remains in the cell as part of the intracellular fluid
ATP- energy production
Involves 3 major stages: Glycolysis, Krebs cycle and cytochrome transport system l
Glycolysis (cytoplasm)
Enter:Glucose
Need:
Niacin
Results:
2 ATP
2 NADH
2 pyruvic Acid (Aerobic: to Krebs cycle; Anaerobic: Lactic Acid formation
Krebs cycle
Enter:
Pyruvic acid-from glucose
Acetyl CoA-from fatty acids
need:
thiamine
niacin
riboflavin
pantothenic acid
Results:
Co2
ATP
3NADH and 1FADH
4 carbon molecule
Cytochrome
Enter:
NADH2 and FADH from glycolysis or the krebs cycle
need:
iron and copper
Results:
25 ATP
Metabolic water
Proteins and fats
Proteins and fats contain potential energy sources
Excess amino acids are deaminated and fit into the Krebs cycle as pyruvic acid
Glycerol is converted into pyruvic acid and fatty acids are split into acetyl groups
Available Energy
potential energy is measured in units called calories or kilocalories
1g carbs=4 kilocalories
1g of protein=4 kilocalories
1g of fat= 9 kilocalories
1g alcohol= 7 kilocalories
Synthesis use of food
Glucose- raw material for the synthesis of pentose sugars
Amino acids- synthesis of the non-essential amino acids by the liver and the synthesis of new proteins in all tissues.
Fatty acids and glycerol- used for synthesis of phospholipids
Metabolic rate
expressed as an amount of heat production
Basal Metabolic rate
energy required for merly livng
Ex:lying quietly in bed
Factor for metabolic rate
Exercise
Age
Body configuration
Sex hormones
Sympathetic stimulation
Decreased food intake
Thiamine(b1)
•conversion of pyruvic acid to acetyl coA in cell respiration
•synthesis of pentose sugars
•synthesis of acetylcholine
Riboflavin (b2)
•part of FAD cell respiration
Niacin (nicotinamide)
•Part of NAD in cell respiration
•Metabolism of fat for energy
B12 (cyanocobalamin)
•Synthesis of DNA, especially in RBC production
•Metabolism of amino acids for energy
•synthesis myelin sheath, especially in the CNS
Folic Acid (folacin)
•Synthesis of DNA, especially in blood cell production
• Contributes to development of fetal CNS
Vitamin C (ascorbic acid)
Synthesis of collagen,
acid)
especially for wound healing
• Metabolism of amino acids
• Absorption of iron
• An antioxidant-prevents cellular damage from free radicals
Vitamin E
•An antioxidant-prevents destruction of the cell membranes
•contributes to wound healing and detoxifying ability of the liver
Vitamin K
•Synthesis of prothrombin and other clotting factors
Calcium
•Formation of bones and teeth
• Neuron and muscle functioning
• Blood clotting
Sodium
•Contributes to osmotic pressure of body fluids
• Nerve impulse transmission and muscle contraction
• Part of bicarbonate buffer system
Potassium
• Contributes to osmotic pressure of body fluids
• Nerve impulse transmission and muscle contraction
Iron
• Part of hemoglobin and myoglobin
• Part of some cytochromes in cell respiration
Iodine
•part of thyroxine and T3
Sulfur
•part of some amino acids
•part of thiamine and biotin
Copper
•Synthesis of hemoglobin
•Part of some cytochromes in cell respiration
•synthesis of melanin
Cobalt
•Part of vitamin b12
Zinc
•Part of carbonic anhydrase needed for CO, transport
• Part of peptidases needed for protein digestion
• Necessary for normal taste sensation
• Involved in wound healing
