Chapter 24 - Nutrition, Metabolism, and Temperature Regulation Flashcards
Nutrient
A substance in food that is used to promote normal growth, maintenance, and repair
H2O
is the major nutrient, 60% comes from food
Carbohydrates
Almost all are derived from plants. Glucose is the major one, we use it for body fuel. Used to make ATP, mostly needed in the brain and RBC’s. Need 125-175g lately.
Lipids
Sourced from plants and animals, most abundant are the neutral fats.
Uses of Lipids
Phospholipids -cell membrane components
Triglycerides -energy source for hepatocytes and muscle
Adipose tissue-protection, insulation, and energy source
Lecithin -used to build the plasma membrane
Cholesterol -Not an energy source, but builds bile salts and steroids
Proteins
For high quality proteins, animals are the best source for essential amino acids. Used for structural components, production of enzymes, production of hormones, production of plasma proteins and antibodies.
Vitamins
Organic compound needed for growth and good health. Never used for energy. Without vitamins, proteins, fats, and carbs would be completely useless. Most are coenzymes or a component of a coenzyme. Vitamins K, B, and D may be produced in the body.
Effects of:
Vitamin A
Important in retinal function, deficiency leads to night blindness
Effects of:
Vitamin D
Deficiency can lead to Rickets in children
Effects of:
Vitamin E
Excess can lead to thrombopoiesis
Effects of:
Vitamin K
Deficiency can lead to prolonged clotting
Effects of:
Vitamin C
Deficiency leads to scurvy
Effects of:
Vitamin B1
Deficiency leads to beri-beri
Effects of:
Vitamin B2
Deficiency leads to dermititis
Effects of:
Vitamin B12
Deficiency leads to pernicious anemia
Effects of:
Niacin
Deficiency leads to pellagra
Fat Soluble Vitamins
Vitamins A, D, E, K
Water Soluble Vitamins
Vitamins C, B1, B2, B12, and niacin
Anabolism
A reaction where larger molecules are built from smaller ones. Ex: Amino acids being builts into proteins
Catabolism
The breaking down of complex structures to simpler structures. Ex: Food being broken down by hydrolysis
Stages of Metabolism
- Digestion in the gastrointestinal tract
- Nutrients are transported by the blood to the cell
- In the mitochondria, O2 makes a complete breakdown of food
- The electron transport chain
Redox Reactions
- Oxidation: when oxygen is gained or H, or e-, is lost
- Reduction: when oxygen is lost or H, or e-, are gained
H+ Acceptors
FAD and NAD
Glycolysis
Ten chemical steps where glucose is converted into 2 pyruvic acid molecules. It occurs in the cytoplams, is anaerobic, and results in 2 ATP per glucose molecule
Kreb’s Cycle
The aerobic pathway, occurs in the mitochondria. 2 pyruvic acid molecules are converted into acetyl CoA. It’s then oxidized, decarboxylated yielding 6 CO2, 8 NADH, H+, 2 FADH2, and 2ATP.
e- Transport Chain
Coenzymes deliver H+ to redox acceptors, H2 is split into H+ and e-. H+ and ATP synthase uses the energy to produce ATP. O2 is the terminal e- acceptor. ETC doesn’t make ATP directly, it generates a proton gradient across the membrane which uses the energy to phosphorylate ADP into ATP.
Net ATP Production
Glycolysis = 2 ATP net
Krebs Cycle = 2 ATP net
ETC = 32 or 34 ATP
Total 36 or 38 ATP per glucose molecule.
Glycogenesis
Glucose catabolism being inhibited by high amounts of ATP. Glucose is then converted to glycogen. The liver and skeletal muscle will synthesize and store glycogen.
Glycogenolysis
When glycogen is broken down into glucose
Gluconeogenesis
The formation of sugar from non-carbohydrate molecules, occurs in the liver when blood glucose levels drop.
Beta Oxidation
Fatty acids are broken down into 2-carbon acetic acid chains and coenzymes. When 2 bind, they enter the Kreb’s cycle as acetyl CoA. Lipid products are transported in the lymph as fatty protein droplets called chylomicrons. Only neutral fats are oxidized for energy. Happens in the mitochondria.
Lipogenesis
Triglyceride synthesis.
Lipolysis
The breakdown of stored fats into glycerol and fatty acids
Ketones
When carbohydrates are deficient, oxaloacetic acid is converted to glucose, and the liver will convert CoA into ketones, this is called Ketogenesis.
Oxidation of Amino Acids
The NH2 must be removed first, it is transferred to glutamic acid. It is then removed as NH3, and combines with CO2 to produce water and urea.
Promotion of Amino Acid Oxidation
There needs to be:
1) A lack of essential amino acids
2) inadequate fat or carbs to produce ATP
3) An excessive amount of proteins in the diet.
Metabolic Rate
The total rate of kilocalorie consumption. The energy expended by the body per unit of time.
Basal Metabolic Rate
The energy needed to perform only the basic, most integral activities
Measuring the Basal Metabolic Rate
It can be measured under standard conditions of:
1) Not eating for 12 hrs or more
2) Be resting of reclined
3) Have the room at room temperature, 35 C.
Thyroxine
The hormone produced by the thyroid. It’s the most important hormone affecting BMR.
Body Temperature
Usually maintained between 97-100 F.
Heat Promoting Mechanisms
(1) Vasoconstriction
(2) Increased metabolic rate
(3) Muscular activity
(4) Thyroxine effect
Heat Loss Mechanisms
(1) Radiation
(2) Conduction/Convection
(3) Evaporation
Role of the Hypothalamus
The major center for temperature regulation.
Fever
Infection, cancer, injury, etc —-> WBC’s arrive —-> Macrophages enter tissues —-> release pyrogens —-> cause neurons to release prostaglandins —-> reset the hypothalamus to a higher temperature —-> cause heat promoting mechanisms
Hypothermia
Low body temperature, due to overexposure to cold
Kwashiorkor
Severe protein deficiency in children. Leads to failure to grow and eventually mental retardation
