Feeding

Question 1

Unlearned and learned components of feeding regulation

Answer 1

some commonents of feeding are innate, like suckling, others we learn

Question 2

What elicits eating behaviors?

Answer 2

sensory experiences

Question 3

Motivation types for eating

Answer 3

• motivation reigns supreme for eating/drinking
• “do i want the food” (incentive motivation) vs “do i need the food”

Question 4

pleasure driven motivation components

Answer 4

• incentive motivation
• flavors, reward, hedonic tone (ability to feel pleasure)

Question 5

Homeostasis driven motivation components

Answer 5

• Do I need the food?
• glucose levels, proteins, fats, salts

Question 6

What is homestasis and what are some examples of it in the body?

Answer 6

• Acheiving and maintaining physiological balance
• Energy, water, temperature, oxygenation

Question 7

What is another way to describe homeostasis?

Answer 7

• maintaining the set point

Question 8

how does the body maintain the set point?

Answer 8

• monitors physiological mechanism
• includes blood glucose, body fat, salt levels, etc and compares to set point

Question 9

What behaviors are encouraged if deficient in terms of homeostasis?

Answer 9

• encourage seeking/feeding
• big difference between a little hungry after class vs. extremely hungry/starving if you get lost while hiking

Question 10

What behaviors encouraged to maintain set point when body is in surplus (in terms of homeostasis)?

Answer 10

• suppress seeking/feeding
• negative feedback regulation

Question 11

What are redundancies?

Answer 11

• multiple mechanisms of maintaining homestasis so if something goes wrong, there are systems in place to compensate

Question 12

What are the three parts associated with thermoregulation?

Answer 12

• Afferents: skin surface, body core, hypothalamus/PONeural
• Neural regions: spinal cord, brainstem, hypothalamus/POA
• Effectors: behavioral responses (shivering/heat seeking and avoiding behaviors) as well as autonomic responses (vasoconstricton/dilation, sweating, respiration, brown-fat stimulation, thyroid hormone secretion)

Question 13

What does POA stand for and where is it located?

Answer 13

preoptic area of the hypothalamus

Question 14

thermoregulation

What do afferents do?

Answer 14

• pick up info and send to neural regions

Question 15

thermoregulation

Neural regions

Answer 15

• goes to spinal cord, ascends to the brainstem, and into the hypothalamic area

Question 16

Effectors

Answer 16

• behavioral: shivering and heat seeking/avoiding behaviors
• autonomic: vasodilation/constriction, respiration, sweating, brown-fat stimulation, thyroid hormone secretion

Question 17

thermoregulation

responses to cold

Answer 17

• increased thyroid activity (thyroid hormone increases metabolism)
• metabolism of brown fat
• constriction of cutaneous blood vessels
• shivering of muscles

Question 18

thermoregulation

responses to heat

Answer 18

• accelerated respiration
• perspiration
• dilation of cutaneous vessels

Question 19

thermoregulation

What happens if the preoptic area of the thalamus is lessioned?

Answer 19

• physiological responses are impaired, without disruption to behavior
• inability for body to adapt/regulate

Question 20

thermoregulation

What happens if you lesion the lateral hypothalamus?

Answer 20

• abolishes behavioral regulation, but does not affect physiological responses such as shivering

Question 21

What is osmolality?

Answer 21

• the number of particles (electrolytes/salts) per unit volume of water

Question 22

What is an isotonic salt solution?

Answer 22

• for most mammals and humans: .9% NaCl
• this is .9 grams NaCl in 100 mL of water

Question 23

hypertonic

Answer 23

more salt than an isotonic solution

Question 24

hypotonic

Answer 24

less salt than an isotonic solution

Question 25

How does water move/in out of cells?

Answer 25

* osmosis * if salt added , water rushes in to dilute * if salt removed, water rushes out

Question 26

Circumventricular organs: Subfornical organ and Organum vasculosum of the lamina terminalis

Answer 26

* on the third ventricle * subfornical organ and OVLT is very important for monitoring thirst * sensitive to how salty the blood is, osmoreceptors * BBB very thin around the OVLT and SFO, allowing this parts of the brain to monitor very efficiently

Question 27

Osmotic thirst

Answer 27

* extracellular compartment filled, but intracellular compartment does not have enough water * high salt concentration (too much!) in extracellular compartment causes water in intracellular compartment to leave (flows out of cells) * caused by regular water loss (respiration, persipiration, urine) or eating something salty

Question 28

What responds to salt levels?

Answer 28

osmoreceptors

Question 29

osmotic thirst from neuronal perspective

Answer 29

* osmosensory neurons in hypothalamus- neurons have osmoreceptors * cells shrink based on water content, ion channels open, action potentials * triggers osmotic thirst * vasopressin release to reduce urination * neurons that directly initiate drinking behaviors are signaled

Question 30

What is hypovolemic thirst?

Answer 30

* too little volume of extracellular fluid due to large water loss (vomiting, hermorrage, diarrhea) * lose water and salts

Question 31

Which type of thirst is characterized by salt and water loss?

Answer 31

hypovolemic

Question 32

What happens during hypovolemic thirst from a bio/hormone perspective?

Answer 32

* blood pressure drops causing... * Baroreceptors (in blood vessels) signal to brain via autonomic nervous system and kidney * Renin (from kidneys), then angiotensis II (in blood) * vasopressin is released * hypovolemic thirst triggered (eat salty food and drink water) * reduces urination and increased blood pressure

Question 33

hypovolemia definition

Answer 33

reduced blood pressure

Question 34

What do baroreceptors measure?

Answer 34

blood pressure

Question 35

hypovolemic thirst process in order (off of diagram)

Answer 35

* kidney baroreceptors-renin-angiotensin II * Subfornical organ * Preoptic area * hypothalamic thirst network-drinking * supraoptic nucleus/paraventricular nucleus- water conservation via vasopressin release

Question 36

Satiety- an anticipatory response

Answer 36

* more satiety when water given through mouth/throat vs. stomach * when able to drink but water diverted via esophagus rats keep drinking * drinking is stopped in anticipation of correcting the extracellular volume and/or osmolality * the cessation of one signal alone will not stop thirst; this redundancy safeguards against dehydration.

Question 38

short term energy storage

Answer 38

* glycogen in muscles and liver * you can convert glycogen to glucose using glucagon

Question 39

how is long-term energy stored?

Answer 39

as adipose tissue

Question 40

Does insulin cause us to feel sated?Why?

Answer 40

* low blood insulin leads to hunger * high blood insulin also leads to hunger since it causes hypoglycemia (low blood sugar)

Question 41

Do blood glucose levels cause us to feel sated?

Answer 41

* no * people with untreated diabetes have high blood sugar levels, but are hungry

Question 42

What causes us to feel sated?

Answer 42

multiple hypothalamic systems

Question 43

What happens if you damage the Ventromedial hypothalamus?

Answer 43

* hyperphagia (over eating) * a new set point that is higher

Question 44

What happens if you damage the lateral hypothalamus (LH)?

Answer 44

* aphagia (inability to eat) * then new set point (lower set point)

Question 45

# body "warns" hypothalamus ab nutrient surplus/deficiency Leptin

Answer 45

* released by fat cells into blood, allow for monitoring of body energy reserves * without it rats keep eating and become obese * both excitatory and inhibitory

Question 46

# body "warns" hypothalamus ab nutrient surplus/deficiency Insulin

Answer 46

* released by pancreas into blood, allows for monitoring of blood glucose levels * inhibitory

Question 47

# body "warns" hypothalamus ab nutrient surplus/deficiency Ghrelin

Answer 47

* released by stomach into blood while fasting, appetite stimulant * excitatory

Question 48

# body "warns" hypothalamus ab nutrient surplus/deficiency PYY(3-36)

Answer 48

* released by intestines into blood while ingesting food, appetite suppressant * inhibitory

Question 49

# hypothalamic circuits for feeding What does the NST do? Where is it located?

Answer 49

* the nucleus of the solitary tract (NST) in the brainstem receives and integrates appetite signals from many sources, some via the vagus nerve

Question 50

# hypothalamic circuits for feeding What is the arcuate purpose?

Answer 50

* hypothalamic mechanisms integrate appetite signals from the arcuate

Question 51

# body "warns" hypothalamus ab nutrient surplus/deficiency Orexigenic neurons

Answer 51

* of the lateral hypothalamus (LH) * act to increase appetite and food intake

Question 52

# body "warns" hypothalamus ab nutrient surplus/deficiency Anorexigenic neurons

Answer 52

* of the paraventricular nucleus (PVN) act to decrease appetite and feeding

Question 53

What does OVLT osmosensory neurons detect?

Answer 53

* osmotic thirst (high solute concentration)

Question 54

What does the subfornical organ detect?

Answer 54

* Angiotensin II (hypotvolemic thirst/low volume)