Nutrition and Metabolism Flashcards
Weight is determined by_____
the bodies energy balance
What type of hormones are involved in appetite control?
peptide hormones
What are the two types of appetite controlling hormones?
- Short term
- long term
What are short-term regulators of appetite?
- Hormones that work over a period of minutes or hours
- Makes you hungry when you begin eating
- make you satiated when you end a meal
What are the four main short-term appetite regulating hormones?
- Ghrelin
- Peptide YY
- Cholecystokinin
- Amylin
What is the function of ghrelin? where does it come from?
- From the parietal cells of the fundus of an empty stomach
- Promotes hunger
- stimulates the secretion of GHRH to absorb nutrients
- stops an hour after feeding
What is the source and function of peptide YY (PYY)?
- Enteroendocrine cells of the ileum and colon after food is detected in the stomach
- Signals satiety and terminate eating
What is the source and function of Cholecystokinin (CCK)?
- Enteroendocrine cells in duodenum and jejunum
- stimulates secretion of bile and pancreatic enzymes
- suppresses appetite
What is the source and function of amylin?
- Beta cells of pancreas
- inhibits stomach activity and produces satiety
What two peptides inform the brain of how mmuch adipose tissue the body has?
Leptin and insulin
Where in the brain do the appetite hormones act?
The arcuate nucleus of the hypothalamus
How does the hypothalamus act on appetite?
Via two different neural networks. One to stimulate and one to inhibit
What hypothalamic peptide is responsible for stimulating appetite?
Neuropeptide Y (NPY)
What hormones stimulate neuropeptide Y?
Grelin
What hormones inhibit neuropeptide Y?
insulin, PPY, and leptin
What hypothalamic hormone is responsible for inhibiting eating?
melanocortin
What hormones stimulate melanocortin?
Leptin
What hormones inhibit appetite stimulants?
endocannabinoids
Hunger is also stimulated by gastric ____
peristalsis
A person is obese when they weigh more than ___% above norm
20
How is bmi calculated?
W/H(squared)
how many kcal/g does alchohol provide?
7.1
What is a nutrient?
Any ingested chemical used for growth, repair, or maintenance
wHAT ARE THE 6 CLASSES OF NUTRIENTS?
Water, Carbs, lipids, protein, vitamins, minerals
What is an essential nutrient?
one that cannot be synthesized by the body
What are the main functions of carbs as a nutrient?
- Act as structure for molecules
- serve as a main fuel source
Carb intake influences ___ of other nutrients
Metabolism
How many grams of glucose does the brain use a day?
120g
What is dietary fiber?
all fibrous material of plant and animal orgin that resists digestion
What are the two types of dietary fiber?
Soluble and insoluble
What are the benifets of soluble fibers?
they decrease LDL levels
What can ow levels of fat intake cause a vitimine deficiency?
Because lipid soluble vitamins rely on fat for absorption
What are the four functions of fat?
- Energy
- Structure of phospholipids and plasma membranes
- Chemical precursors
- protection and insulation
Fat should make up less than ___ of daily calorie intake
35%
How are lipids transported in plasma?
Via lipoprotein complexes
What are lipoprotein complexes?
Tiny droplets with a core of cholesterol and triglycerides all with a protein coat
How are lipoproteins classified? how many classifications are there?
- By density
- 4
What are the four lipoproteins?
- VLDL
- LDL
- HDL
- Chylomicrons
Where do VLDL’s come from and what is their function?
- Come from the liver
- Transport lipids to adipose tissue
- Become LDL’s after they transport
What two ways does the body use LDL’s
- Absorbed by cells in need of cholesterol
- Digested to release cholesterol for intercellular use
WHat is the function of HDL’s?
- They start as an empty shell
- The travel through the blood and pick up cholesterol and phospholipids
- Pass picked up lipids to the liver for elimination
High LDL’s levels correlate with___
cholesterol deposition in arteries
RDA for protein is
46-56 g/day
How many amino acid are essential?
8
How many amino acids are inessential?
12
What is net protein utilization?
the percentage of amino acids in a protein that the human body uses
What is nitrogen balance?
The rate of nitrogen ingested equals nitrogen excreted
When does a positive protein balance occur?
When nitrogen ingestion exceeds its excretion
- Childhood
- Pregnancy
- excess growth hormone and sex steroids
When does a negative nitrogen balance occur?
During starvation and stress
What are minerals?
Inorganic eements that plants extract from soil or water
What are vitamins?
dietary organic compounds that are necessary for metabolism
Gross function of phosphorus?
Structural component and component of phosphate buffer system
Gross functions of calcium, iron, magnesium, and manganese?
they act as cofactors for enzymes
Main function of chlorine?
component of stomach acid
What four vitimins can the body synthesize from provitimins?
Niacin
Vit. A
Vit. D
Vit. K, pantothenic acid, biotin, folic acid produced from bacteria
What is the function of oxidative carbohydrate metabolism?
To transfer energy from glucose to ATP
What are the three major pathways of glucose catabolism?
- Glycolysis
- Anaerobic fermentation
- Aerobic respiration
WHat is glycolysis?
when a glucose is split into two pyruvate molecules
What is anaerobic fermentation?
When pyruvate is reduced to lactate in the absence of oxygen
What is aerobic fermentation?
Pyruvate is oxidized into CO2 and H2O
What are the two major co-enzymes in glucose catabolism?
NAD+-from niacin
and FAD-from riboflavin
What is added to NAD+ to become NADH?
2H combinds with one NAD+ and results in on NADH and one H+
What is added to FAD to make FADH2
2H is added
What is the first step of glycolysis?
Phosphorylation
What is phosphorylation?
When ATP donates a phosphate group to a glucose to produce glucose 6-phosphate
facilitated using the hexokinase enzyme
What is the next step in glycolysis after Phosphorylation?
Priming
What occurs during the priming stage of glycolysis?
2 ATP’s are used to rearrange G6P (becomes isomerized)
What occurs after priming in glycolysis?
Cleavage
What occurs during the cleavage stage in glycolysis?
six carbon G6P is cleaved into three carbon compounds
What occurs after the cleavage stage in glycolysis?
Oxidation
What occurs during the oxidation stage of glycolysis?
- Each 3 carbon compound is oxidized by removing a pair of hydrogen and attaching them to NAD+ to make NADH
- A phosphate group is added to each carbon fragment
What occurs after oxidation in glycolysis?
Dephosphorylation
What occurs during dephosphorylation?
- Phosphate groups are removed from carbon fragments and added to ADP to make ATP
- 3 carbon compounds become pyruvate
How much ATP is netted from glycolysis?
2 ATP per glucose
What are the end products of glycolysis?
- 2 pyruvate
- 2 NADH
- 2 ATP
- 2 H+
What is the fate of pyruvate after glycolysis?
anarobic fermentation or aerobic respiration depending on oxy. availability
What are the two principal steps of aerobic respiration?
- Matrix reactions-controling enzymes in fluid of mitochondria
- Membrane reactions-enzymes bound to membranes of mitochondria
What is the first step in the matrix reactions of aerobic respiration? what occurs during this step?
- The transition step
- Pyruvate is prepared to enter citric acid cycle
What happens to pyruvate during the transition step?
CO2 is removed, NAD+ removes hydrogen atoms and a coenzyme is added to make Acetyl-coenzyme A (Acetyl-CoA)
What occurs after the transition step?
The citric acid cycle begins
What occurs during the citric acid cycle?
- A series of reactions that take starts with acetyl-CoA combinding to make citric acid
- That citric acid continues to donate carbons producing NADH
- as well as producing ATP and FADH before it start again
The electron transport chain is a ___ reaction
Membrane
What are the two purposes of membrane reactions?
To further oxidize NADH and FADH2 and turn them into ATP
What is the mitochondrial electron transport chain?
series of
compounds that carry out this series of membrane reactions To further oxidize NADH and FADH2 and turn them into ATP
What is the final electron acceptor in the electron transport chain?
Oxygen
How are NADH and FADH formed into ATP?
The H+ are transported from the matrix space of the mitochondria to a space between the membranes.
-This creates a H+ graident and causes an influx of H+ back into the matrix.
This influx creates energy that produces ATP
What is the total amount of ATP generated by one glucose molecule via oxidation of glucose?
32
What is Glycogenesis?
The synthesis of glycogen
What stimulates glycogenesis? what occurs?
- Insulin stimulates it
- It occurs by the chaining of glucose monomers
What is glycogenolysis?
The hydrolysis of glycogen
When is glycogenolysis occur and what stimulates it?
- between meals to release glucose
- Glucagon and epinephrine stimulate it
Where i the glucose released back into the blood after glycogenolysis?
the liver
What is gluconeogenesis? where does it occur?
- The synthesis of glucose from noncarbohydrates such as glycerol and amino acids
- occurs in the liver
What form is fat stored in the body and where is it stored
As triglycerides in adipocytes
What is lipogenesis?
The synthesis of fat from other types of molecules
What molecules can be combined to make fat?
- Amino acids and sugars
- glucose
- Acetyl-CoA uses to make fatty acids
Lipid metabolism begins with the ____ of ____(stored fats)
Hydrolysis of Triglycerides
What is the product of triglyceride hydrolysis?
Glycerol and fatty acids
What happens to the glycerol product of triglyceride hydrolysis?
it is added to the pathway of glycolysis to produce ATP only half as much as glucose
What happens to the fatty acid product of triglyceride hydrolysis?
- Beta oxidation in the Mitochondrial matrix
- 2 carbon atoms bind to coenzyme a to make acetyl-CoA
What is the fate of the acetyl-CoA produced by lipid metabolism?
- Used in the krebs cycle
- metabolized by the liver to produce ketone bodies
what must happen first In order for the body to use amino acids directly as fuel?
they must first be deaminated
removal of -NH2
How is the amino acid used after it is deaminated?
it is converted into pyruvate, acetyl-CoA, or an acid in the citric acid cycle
What is the metabolic source of ammonia?
- When amino acids are deaminated it is converted into glutamic acid
- In the live the glutamic acid has its -NH2 removed
- The NH2 becomes NH3 (ammonia)
- Liver combines NH3 with CO2 to produce urea
- Urea is excreted from the body in urine
What is an absorptive state?
It is a fed state
How long does the absorptive state last?
about 4 hours after meal
What is occuring in an absorptive state?
Nutrients are being absorbed and may be used immediately to meet energy needs
What is a postabsorptive state?
A fasting state
What is occuring during a postabsorptive state?
- Stomach and intestines are empty
- Body meets energy needs with stored fuel
What is the major source of fuel in an absorptive state?
Dietary glucose
The major metabolic thrust during an absorptive state is___
anabolism of energy storage
What happens to amino acids in an absorptive state?
they become proteins
What happens to glycerol and fatty acids in an absorptive state?
They are converted into triglycerides
What happens to excess amino acids in an absorptive state?
They are deaminated and used for energy or stored as fat in the liver
What is the major regulator of the absorptive state?
Insulin
What is the major etabolic thrust during a postabsorptive state?
the catabolism and replacement of fuels in the blood
What happens to proteins during a postabsorptive state?
The are broken down into amino acids
What happens to Triglycerides during a postabsorptive state?
They are turned into glycerol and fatty acids
What happens to glycogen during a postabsorptive state?
it becomes glucose
What are the major energy fuel’s in a postabsorptive state?
Fatty acids and ketones
What is the main regulator of the postabsorptive state?
the sympathetic nervous system and glucagon
The metabolic rate is defined as-
The amount of energy liberated in the body in a given period of time
How is metabolic rate directly measured?
with a calorimeter
How is metabolic rate indirectly measured?
a spirometer measuring the amount of oxy a person uses
What is the basal metabolic rate?
– A baseline or standard of comparison that minimizes the effects of activity, feeding, and hormone levels
What is the total metabolic rate?
The sum of the BMR and energy expenditures for voluntary activities
What is thermoregulation?
—the balance between heat
production and loss
Why is thermotegulation so important?
Because the enzymes in the body depend on an optimal, stable working temp.
The best estimate of core body temperature is from the-
rectum
What is average core body temp
99.0-99.7
What is shell temperature?
The temperature closer to the surface (oral temp, skin temp)
Where does most of the body’s heat come from?
Exergonic chemical reactions such as nutrient oxidation and ATP usage
What are the four ways the body loses heat?
- Infrared radiation via moving moecules
- Conduction of heat from the body to things touching it
- convection of heat to moving fluids
- Evaporation
How is thermoregulation achieved?
via negative feedback loops
What is the hypothalamic thermostat?
The preoptic portion of the hypothalamus that functions as the body’s thermostat
How does the hypothalamic thermostat monitor body temp
through the monitoring of blood temp via signals from the peripheral thermoreceptors in the skin
-sends signals to appropriate centers
What is the heat-loss center of the brain?
In the anterior hypothalamus
Where is the heat-promoting center of the brain?
near the mammillary bodies of the brain
What occurs when heat-loss centers activate in response to high blood temp?
- causes cutaneous vasodilation
- triggers sweating if needed
- inhibits heat-promoting center
What occurs when the heat-promoting center detects low blood temp
- Causes vutaneous vasoconstriction to retain warm blood deeper in the body
- causes shivering to produce heat
How is heat produced longterm?
Metabolic rate is increased
What is behavioral thermoregulation?
the adding or removal of clothing
What is fever
a normal protective mechanism that should be allowed
What are the three main dangers of prolonged heat exposure?
- Heat cramps-due to electrolyte imbalance from sweating
- Heat Exhaustion-from severe water and electrolyte loss
- Heat stroke- core body temp rises above 104
What occurs if core temp drops below 91 degrees
Hypothermis occurs
- metabolic rate drops so low that body cant maintain heat production
- causes more tempture drop
