phys2test3part2 Flashcards
What does satiety mean?
Desire for food is satisfied.
With metabolism the hypothalmus receives input from where?
GI, CNS, Adipose.
What part of the hypothalamus is the feeding center?
Lateral nuclei.
What will the feeding center or lateral nuclei of the hypothalamus do?
Drives search for food.
What happens when the lateral nuclei or feeding center of the hypothalamus is stimulated?
Hyperphagia (constant hunger) and obesity.
What happens with destruction of the lateral nuclei or feeding center of the hypothalmus?
Lack of desire for food.
What part of the hypothalamus is the satiety center?
Ventromedial nuclei.
What happens when the satiety center or ventromedial nuclei of the hypothalamus is stimulated or damaged?
Stimulated- Satiety and aphasia. Damaged- Voaracious and continued eating.
Besides the lateral nuclei what part of the hypothalamus will control feeding?
Dorsomedial nuclei.
Besides the ventromedial nuclei what part of the hypothalamus will control satiety?
Paraventricular nuclei.
Modulation of feeding happens in the arcuate nucleus of the hypothalmus and is affected by what?
GI/adipose hormones.
What are the 2 neurons in the arcuate nucleus of the hypothalamus?
POMC, Orexigenic.
What will the POMC do?
Decreases intake of food and increases energy expenditure.
What will the Orexigenic do?
Increases food intake and decreases energy expenditure.
What are the hormones that regulate appetite?
CCK, Leptin, Insulin, Ghrelin.
What is released from the orexigenic neurons and what will they do?
AGRP antagonist at melanocortin receptors to inhibit effects of alpha-MSH (Eat more). NPY- inhbits POMC firing and increases appetite.
Defects in the signaling of the POMC pathway will do what?
Cause extreme obesity.
What is the most common defect of the POMC pathway?
MCR-4
What happens with excessive stimulation of the POMC pathway?
Anorexia and wasting.
What are 3 of the short-term food regulation that turn eating off?
Oral factors, GI filling, GI hormones.
What is a short-term food regulation that turns eating on?
Ghrelin.
Where will ghrelin be released from?
Oxyntic cells of stomach and intestine.
What is the glucostatic/aminostatic/lipostatic theory?
Low glucose/amino acids/ fatty acids= hunger and feeding. High glucose/ amino acids/ fatty acids= increased firing of the paraventricular and ventromedial nuclei which is the satiety center and decreased eating.
What is the adipose feedback system?
Adipocytes—> leptin —> signals excess energy storage—-> inhibits appetite.
In the last decade excess body fat has increased by how much?
30%.
How many USA adults are overweight and how many are obses?
overweight- 64% and 33% are obese.
Each 9C of excess equals what?
1g of fat.
How many more adipocytes will obese people have and what are the adipocytes size like?
Obese people have 4 times as many adipocytes and they are 2 times the normal size.
What is the % of body fat in females and males?
Females- 35% males- 25%.
What are the causes of obesity?
Genes, lifestyle/diet/environment. Genes play a lesser role than the other stuff.
A single episode of strenuous activity increases the BMR for how long?
Hours.
How much energy is needed for muscular activity in an average person vs. a laborer?
Average person- 25-30%. Laborer- 60-70%.
How common is an abnormal ventromedial nuclei in obese people?
Rare.
What % of obese people have genetics as a related cause?
20-25%.
With a BMI (body mass index) of 25-30 how many Calories less should we eat to lose weight?
500C/day, and increase activity.
With a BMI (body mass index) greater than 35 how many Calories less should we eat to lose weight?
500-1000C/day with increased activity.
What are sympathomimetics?
Drugs that decrease hunger.
What are the problems with sympahtomimetics?
Cause CNS stimulation and hypertension, and adaptation occurs wo weight loss is only 5-10%.
Surgery in obese people decreases mortality by up to what %?
40%.
What % of obses people who had surgery to reverse the obesity will have a reversal of obesity?
75-85%.
What type of obese people are candidates for surgery?
Those with BMI above 40 or above 35 with DM or HTN.
What are the health effects of surgery on obses people?
Nutritional deficiency.
What is inanition?
Starvation.
What is anorexia?
Reduction in food intake caused by central neural processes.
What is Cachexia?
Metabolic increased energy expenditure.
What is the wasting syndrome of AIDS and cancer?
Cachexia.
What is starvation?
Depletion of food stores in body tissues.
What will the body use for energy in starvation?
CHO.
How much glycogen is stored in the body and where is it at?
Only few 100g stored as glycogen in liver/muscles. Enough energy for 1/2 day.
What is the problem with using fat for energy?
Fat makes ketones that can cross the BBB and cause ketosis.
With starvation how are proteins consumed?
rapid depletion at first and then slowed depletion until fat store is depleted, and there will be a rapid depletion before death.
With starvation what happens to water soluable vitamins?
They are depleted in several weeks.
What is metabolism?
All bodily chemical reactions.
What is metabolic rate?
Rate of heat liberation of bodily chemical reactions.
What is a Calorie?
A unit of energy released from foods or expended by bodily processes.
1 calorie will raise 1g of water how many degrees?
1 degree C.
1 calorie = 1000 calories = 1 kilocalorie which equals what?
Unit of metabolism.
How many calories will a man in bed all day need?
1650 calories.
How many calories will a man in bed and eating need a day?
1850 calories.
How many calories will a man sitting in a chair all day need?
2250 calories.
Physical activity increases energy expenditure by how much?
25%.
Walking stairs takes how much more energy than lying in bed?
17 times.
A laborere uses how many calories a day?
6000-7000 calories a day.
What is the BMR (basal metabolic rate)?
Minimum energy expenditure for body to exist.
Skeletal muscle uses how much of the BMR?
20-30%.
What will thyroxine do to the BMR?
Increase it 50-100%. While a loss of thyroxine can decrease BMR 40-60%.
What will testosterone do to the BMR?
Increase it 10-15%.
What will GH do to the BMR?
Increase it 15-20%.
What will a fever do to the BMR?
Increase it 120% for every 10 degrees C.
What will sleep do to the BMR?
Decrease it 10-15%.
What will malnutrition do to the BMR?
Decrease it 20-30%.
What will the skin temperature be?
the surface varies with temperature of surroundings.
What is the normal core temperature?
97-99.5 degrees F.
What is the average body temperature?
98.0- 98.6 degrees F.
What temperature will be considered extreme cold and extreme hot?
cold- below 96, and hot- 101-104.
Rate of heat production is what?
Metabolic rate of the body.
What makes up 60% of how heat is lost?
Radiation infrared heat rays, electromagnetic waves.
How much heat is lost through conduction?
15%, but it requires heated air to be continually moved away from skin.
When temperature of surroundings is greater than skin what is the only method of cooling?
Evaporation.
How is sweating accomplished?
Anterior hypothalamus—> autonomic pathways to spinal cord—-> sympathetic outflow—> sweating.
What hormones stimulate sweating?
Cholinergic (Ach) and EPI/norepi.
Epi/norepi are important stimulators of sweating glands when?
During excersise.
What is the composition of sweat like?
Similar to plasma.
What part of the brain will detect temperature?
The preoptic area of the anterior hypothalamus.
What will help to prevent hypothermia?
Shivering, inhibiting sweating, vasoconstriction.
Name 3 temperature decreasing mechanisms?
- Vasodilation. 2. Sweating. 3. Decrease in heat production.
How is vasodilation done?
Inhibiting sympathetic system.
Name 3 ways to increase temperature?
- Vasoconstriction. 2. Piloerection. 3. Increased heat production.
How is vasoconstriction done?
Sympathetic stimulation.
How important is piloerection in increasing temperature?
of little importance in humans.
How can piloerection increase temperature?
Traps a layer of air for insulation next to the skin.
What can cause a fever?
Brain or toxin.
What temperature will cause heat stroke?
105-108 degrees F.
What are the symptoms of heat stroke?
Dizziness, GI distress, vomit, delirium, LOC.
How can brain lesions cause a fever?
Compression or damage to hypothalamus.
What are febrile diseases?
Pyrogens: breakdown products of bacteria or tissues which causes a rise of set points of hypothalamus and recruits heat production and heat conservation and causes a fever.
Exposure to ice water for 20-30 minutes causes death due to what?
Heart standstill or fibrillation.
What cold temperature will cause death?
77 degrees F.
What is frostbite?
Freezing of bodily surfaces.
What is ice crystals in skin?
Permanent damage of cells/vessels.
Name 4 roles of cholesterol?
- Membrane component. 2. Steroid synthesis. 3. Bile acid/salt precursor. 4. Vitamin D precursor.
Name 3 sources of cholesterol?
- Diet. 2. De novo synthesis. 3. Cholesterol synthesized in extrahepatic tissues.
What is a major dietary source (animal product) of cholesterol?
eggs.
We absorbe what % of dietary cholesterol?
50%.
Increased intake of dietary cholesterol equals what?
Decreased absorption.
How much dietary cholesterol is excreted a day and in what form?
1 g/day in bile acids.
If we assume 400 mg intake a cholesterol a day how much is absorbed and how much is excreted?
Absorbed-200mg. Excreted- 1000mg.
So if we assume 400 mg cholesterol intake a day how much de novo synthesis of cholesterol is made?
800 mg a day.
How will lowering cholesterol intake effect blood cholesterol?
Very little effect.
Cholesterol synthesis is similar to what pathway?
Ketogenic.
Where will cholesterol synthesis happen at?
In cytosol.
What is needed for cholesterol synthesis?
NADPH and ATP.
How regulated in cholesterol synthesis?
It is highly regulated.
What areas of the body will cholesterol be synthesized at?
80% in liver, 10% in intestines, 5% in skin.
What is HMG CoA reductase used for?
Enzyme used in synthesis of cholesterol.
How many enzymes are used in synthesis of cholesterol?
Many.
What is the short term regulation of HMG CoA reductase?
Inhibited by phosphorylation.
HMG CoA reductase is phospharylated and made active by ATP so when ATP is low what happens?
The body wont waste energy on cholesterol synthesis and wont phospharylate the HMG CoA reductase.
What is proteolysis and how will it be a long term regulation of HMG CoA reducatse?
It is breaking down of proteins into smaller substances.
What will cholesterol and cholesterol metabolites do to HMG CoA reducatse?
It has a negative feedback and will cause a long term regulation of HGM CoA reductase.
What will SREBP-2 and SREBP-1c do?
These both are transcriptional regulations of cholesterol synthesis. SREBP-2= mainly regulates cholesterol synthesis. SREBP-1c= mainly regulates fatty acid synthesis.
Transcriptional regulation of cholesterol synthesis responds to cellular levels of what?
Sterols.
What happens when sterol levels are low?
SREBP-2 is released.
How will statins decrease cholesterol?
By decreasing HMG CoA reducatase activity.
What will Bile sequestering agents do?
Lower cholesterol by binding bile acid and then more bile acids will need to be made from cholesterol.
What will oat bran do to cholesterol?
Lower it because it is a soluable fiber.
What will Niacin do?
Inhibits VLDL excretion and may cause a fatty liver, but 3-8 grams a day will lower cholesterol.
What is RYR?
Red yeaste rice.
RYR will do what?
Lowers cholesterol by acting like a statin and decreasing the HMG CoA reductase activity.
Name 2 other things that will lower cholesterol?
Policosanols and garlic.
