Week 6 - Ingestive Behavior

Question 1

Ingestive Behavior

Answer 1

A correctional mechanisms that replenish the body’s depleted stores of
water or nutrients.

Question 2

Intracellular vs extracellular fluid

Answer 2

Intracellular: 2/3 volume

Extracellular: 1/3 volume

plus a tiny bit of csf

Question 3

Types of extracellular fluid

Answer 3

Intravascular: blood plasma

Interstitial: fluid that bathes the cells

Question 4

Tonicity

Answer 4

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

Question 5

Types of tonicity

Answer 5

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

Question 6

Negative vs positive feedback loops

Answer 6

Question 7

Negative feedback loop: satiety mechanisms

Answer 7

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)

Question 8

types of thirst

Answer 8

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

Question 9

Osmometric Thirst

Answer 9

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

Question 10

Volumetric thirst

Answer 10

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

Question 11

Osmoreceptors

Answer 11

a neuron that detects changes in solute conc. of interstitial fluid

Located in the Lamina Terminalis (wall of third ventricle)

Question 12

Natural dying

Answer 12

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

Question 13

Hunger hormone

Answer 13

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)

Question 14

Low vs high levels of ghrelin

Answer 14

LOW: increase of cortisol, leads to stress and anxiety

HIGH: decreases cortisol, leads to reduced stress and anxiety (why you stress eat)

Question 15

Prader-Willi Syndrome

Answer 15

Genetic multi-system d.o.

Experience hyper-phagia d/t excessive levels of grhelin (never feel satiated)

Question 16

Hypothalamus and Eating

Answer 16

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

Question 17

Weight loss: gastric band

Answer 17

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)

Question 18

Weight loss: Wegovy (semaglutide)

Answer 18

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

Question 19

Obesity

Answer 19

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.

Question 20

Obesity and food addiction

Answer 20

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

Question 21

Sensory and social factors for eating

Answer 21

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

Question 22

Pepsi Paradox and Eating

Answer 22

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)

Question 23

Supplements: deficiency vitamin D

Answer 23

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

Question 24

Supplements: magnesium deficiency

Answer 24

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

Question 25

Supplements: Omega-3 Fatty Oils

Answer 25

Add on treatment for depression (strong evidence good with therapy)

For ADHD, some evidence could be helpful

Question 26

Anorexia: impact

Answer 26

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!

Question 27

Anorexia: Research

Answer 27

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?

Question 28

Anorexia treatment

Answer 28

CBT, increasing eating speed, stimulation of ACC

Question 29

Blumia nervosa

Answer 29

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)

Question 30

Bulimia nervosa: vomiting

Answer 30

*Vomiting only eliminates approximately 25% of the calories consumed BUT

Prolonged dehydration & electrolyte depletion = 5x ↑ risk of heart a􀆩ack, overall risk of hypovolemic shock, kidney failure, UTI