Week 6 - Ingestive Behavior Flashcards
Ingestive Behavior
A correctional mechanisms that replenish the body’s depleted stores of
water or nutrients.
Intracellular vs extracellular fluid
Intracellular: 2/3 volume
Extracellular: 1/3 volume
plus a tiny bit of csf
Types of extracellular fluid
Intravascular: blood plasma
Interstitial: fluid that bathes the cells
Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water via osmosis (AKA ability to do osmosis)
Relationship between interstitial and
intracellular –> Solute conc. determines movements
Types of tonicity
Tells you where that water is moving
Isotonic: equal concentration on both sides (no movement)
Hypertonic: more solute
–> If interstitial fluid is Hypertonic (more solute), water moves out of
cells
Hypotonic: less solute
–> If interstitial fluid is Hypotonic (less solute), water moves into cells
REMEMBER: WATER FOLLOWS SALT
Negative vs positive feedback loops
Negative feedback loop: satiety mechanisms
Empty stomach triggers hunger –> eat –> triggers satiation (the opposite response)
Stop behavior in anticipation of replenishment
Hunger negative feedback loops take time to reach the brain (20 minute delay, why easy to overeat)
types of thirst
Osmometric thirst: when tonicity of interstitial fluid increases
–> thirst triggered by cell dehydration
–> ex. eat salty foods, fluid around cells is salty, cells pumping water out, you feel thirsty
Volumetric thirst
- when intravascular (blood plasma) volume decreases AKA HYPOVOLEMIA
- Causes: bleeding, vomiting, diarrhea
- leads to: increased blood pressure, inhibition of water and sodium secretion
Osmometric Thirst
Occurs when the fluid content INSIDE (aka Intracellular fluid) the cell decreases – usually because not enough water has been consumed to compensate for food intake i.e., salty food
As a result, water is drawn from the OUTSIDE surrounding fluid (aka extracellular fluid) into the cell.
Water moves from Extracellular to Intracellular
Volumetric thirst
Volumetric Thirst
Occurs when the blood volume drops due to a loss of extracellular fluid (the outside surrounding fluid)
As a result, water is drawn from inside the cell to the outside
Can be caused by sweating, vomiting, diarrhea, and blood loss
Water moves from Intracellular to Extracellular
Osmoreceptors
a neuron that detects changes in solute conc. of interstitial fluid
Located in the Lamina Terminalis (wall of third ventricle)
Natural dying
Dehydration of cells is part of body’s natural dying process
IV fluids do not remain in the vascular system instead cause:
- edema
- swelling
- eventual respiratory distress (fluid just gathers in lungs because dying body doesn’t absorb water)
Reduction in eating = ketosis which results in
- reduction in appetite and thirst
- pain relief
- euphoria
body purposefully goes into state of fatigue to help you die peacfully
Hunger hormone
Grhelin: hormone released by the stomach when you are fasting or the digestive system is empty
*think ghrelin = growling stomach
Ghrelin binds to receptors in the hypothalamus –> Activates Orexin producing neurons –> Stimulates eating behaviors/hunger e.g., GI contraction “growling”
Increases BEFORE eating, decreases AFTER eating (satiating mechanism)
Low vs high levels of ghrelin
LOW: increase of cortisol, leads to stress and anxiety
HIGH: decreases cortisol, leads to reduced stress and anxiety (why you stress eat)
Prader-Willi Syndrome
Genetic multi-system d.o.
Experience hyper-phagia d/t excessive levels of grhelin (never feel satiated)
Hypothalamus and Eating
lateral hypothalamus:
- stop eating and drinking when destroyed
- overeating when activated
- produces orexin (motivated to go find food)
Ventromedial hypothalamus:
- suppression of eating when activated
- overeating when destroyed
Rats: Rats will continue to eat as long as LH is simulated, and will eat to double their weight when VMH is removed
Weight loss: gastric band
Reduced for first 8 months of adjustable gastric band - reduced volume = ghrelin levels drop sooner
At 8 months, 53% higher than pre-surgery (your body learns to compensate)
Not seen in gastric bypass (because you are bypassing the stomach so ghrelin not at play)
Weight loss: Wegovy (semaglutide)
FDA approved 2021
Augments insulin secretion to inhibit release of glucagon
Increased risk of problems with gall bladder, kidney, diabetic retinopathy, depression, suicidal thoughts/behaviors
Obesity
14 in the world
Use BMI (flawed method)
2x in adults, 3x in adolescents since 2000
- Pandemic increased for both (adults up by 3%, 5-11 y.o. up by 9%)
“Overweight individuals’ normal cholesterol and blood pressure levels can still go on to develop heart disease at higher rates BUT Diabetes, hypertension and cholesterol carry higher burden” (Bowers, 2012)
–> AKA obesity is a risk factor, but not as much as hypertension, diabetes, cholesterol, etc.
Obesity and food addiction
Dopamine level changes result in withdrawal symptoms
Combination of naltrexone (an opioid antagonist) and bupropion (a dopamine agonist) produced significant weight loss among individuals with obesity
AKA they blocked the reward system
Sensory and social factors for eating
Experience of eating helps us feel satiated: will feel more full after drinking soup vs direct tube feed into stomach
Nutrition value important
As you increase in age, decrease how receptive you are to taste (why older people like saltier foods)
More options leads to larger intake of food
Larger plate size leads to increase intake of food
Pepsi Paradox and Eating
Blind taste test vs. at home environment of pepsi and coke
when blinded, people preferred pepsi (sweeter)
But when saw label, people preferred coke
–> branding is important
–> VMPFC Activation in loyalists (moral piece, i am a coke loyalist)
Supplements: deficiency vitamin D
Correlated with depression/negative emotions
Concurrent use with anti-depressants supportive –> good depression treatment
the more melanin your skin has, the harder it is to synthezize vit d
Supplements: magnesium deficiency
w/stress can increase agitation, anxiety, sleeplessness, headaches, and apathy
Can treat restless leg syndrome
Slow response time to reach steady state via oral supplementation (30+ weeks) –> if you are VERY defficient, might need infusion
Supplements: Omega-3 Fatty Oils
Add on treatment for depression (strong evidence good with therapy)
For ADHD, some evidence could be helpful
Anorexia: impact
Hereditary: 58-76% in twin studies
Assocaited with:
- loss of gray and white matter in the brain
- enlarged ventricles and widened sulci (shirnkage of brain tissue)
- inhibited emotional facial expression despite reporting similar or more intense emotions (saying they are really depressed byt not showing it)
- tissue loss can be revered with successful treatment!
Anorexia: Research
Starvation study:
* 6 months ate at 50% of baseline
* Loss 25% body weight
* Demonstrated preoccupation w/food, ritualistic eating, erratic mood, impaired cognition, slowed eating/lingering
* Post-study = complained of fat on their abdomens and legs
Excessive exercise:
* starved mice run on wheel more than well-feed mice –> food seeking?
Gender differences:
* women ate less post-fast than men
restricted food access = starvation = anorexia?
Anorexia treatment
CBT, increasing eating speed, stimulation of ACC
Blumia nervosa
Associated with:
- decrease blood flow to the precuneus (self-perception and memory) –> food as a means of self-distraction?
- amygdala activation (higher activation when eating than control, stable when eating post-fasting. higher activation of amy. reduces PFC fucntion, so not in control)
- Feedback loop:
–> anticipation of binge, consumption of junk food, anticipation of purging, purging (vomiting reduces pain, relases oxytocin), stress (creases binge-purge cycle)
Bulimia nervosa: vomiting
*Vomiting only eliminates approximately 25% of the calories consumed BUT
Prolonged dehydration & electrolyte depletion = 5x ↑ risk of heart aack, overall risk of hypovolemic shock, kidney failure, UTI
