Chapter 12: Ingestive Behavior Flashcards
1
Q
Homeostasis
A
Process by which the body’s substances and characteristics are maintained at their optimal level
2
Q
Ingestive Behavior
A
Eating or drinking
3
Q
Essential features of regulatory mechanism
A
- System variable
- Set point
- Detector
- Correctional mechanism
4
Q
System variable
A
Variable that is controlled by regulatory mechanisms
5
Q
Set Point
A
Optimal variable in regulatory mechanism
6
Q
Detector
A
In regulatory process, mechanism that signals when system variable deviates from its set point
7
Q
Correctional Mechanism
A
Mechanism that is capable of changes value of system variable
8
Q
Negative Feedback
A
Process whereby effect produced by an action serves to diminish or terminate that action
9
Q
Satiety Mechanism
A
Brain mechanism that causes cessation of hunger or thirst, produced by adequate and available supplies of nutrients or water
- Monitor activity of correctional mechanism, not system variables themselves
10
Q
Intracellular Fluid
A
Fluid contained within cells
- Losing intracellular water deprives cells of ability to perform many chemical reactions and gaining water can cause membrane to rupture
11
Q
Extracellular Fluid
A
All body fluids outside cells
- Interstitial fluid, blood plasma, and CSF
12
Q
Intravascular Fluid
A
Fluid within blood vessels
- Volume of intravascular fluid must be closely regulated because of mechanism of operation of heart
13
Q
Hypovolemia
A
Reduction in volume of intravascular fluid
14
Q
Osmometric Thirst
A
Thirst produced by an increase in osmotic pressure of interstitial fluid relative to intracellular fluid, thus producing cellular dehydration
15
Q
Osmosis
A
Movement of water through semipermeable membrane from region of low solute concentration to one high solute concentration
16
Q
Osmoreceptors
A
Neurons that detects changes in solute concentration of interstitial fluid that surrounds it
- Located in lamina terminalis
17
Q
Lamina terminalis
A
- Contains 2 specialized circumventricular organs: OVLT and SFO
- Found in hypothalamus, in region that borders anteroventral tip of 3rd ventricle (AV3V)
- Lack BBB
18
Q
Volumetric Thirst
A
- Thirst produced by hypovolemia
- Involves loss of Na+ and water, volumetric thirst leads to salt appetite
- Cells in kidney detect decreases in blood flow
- In response to low blood volume, kidneys are responsible for presence of hormone angiotensin
- Baroreceptor cells
19
Q
Angiotensin
A
Peptide hormone that constricts blood vessels, causes retention of Na+ and water and produces thirst band salt appetite
- Causes kidneys to conserve water and salt and increases blood pressure - Reduced blood flow to kidneys causes water and salt to be retained
20
Q
Baroreceptor cells
A
Stretch sensitive and detect when blood volume in heart falls
- located in atria - reduced blood flow to heart increases drinking and severing nerves to atrial baroreceptor decreases drinking
21
Q
Cells in liver convert glucose into […] and it is stored, and are stimulated to do so by presence of […]
A
Cells in liver convert glucose into glycogen and it is stored, and are stimulated to do so by presence of insulin
22
Q
Glycogen
A
Polysaccharide often referred to as animal starch
- stored in liver and muscle - constitutes short-term store of nutrients
23
Q
Insulin
A
Pancreatic hormone that facilitates entry of glucose and amino acids into cell, conversion of glucose —> and transport of fats into adipose tissue
- mice with mutation of insulin receptors in brain became obese
24
Q
Fall in glucose is detected by cells in […]
A
Fall in glucose is detected by cells in pancreas and brain
- Pancreas responds by stopping its secretion of insulin and starting to secrete glucagon
25
Glucagon
Pancreatic hormone that promotes conversion of liver glycogen into glucose
26
Long-term reservoir consists of […]
Long-term reservoir consists of triglycerides
27
Triglycerides
- form of fat storage in adipose cells
| - consists of molecule of glycerol joined with 3 fatty acids
28
Glycerol
Converted by liver into glucose
29
Fatty Acids
Can be metabolized by most cells of body expect for brain
30
Adipose tissues
Found beneath skin and abdominal cavity
- Cells are capable of absorbing nutrients from blood, converting them to triglycerides, and storing them
- Size of fat cells is determined by amount of TAGs the cells contain
31
[…] is involved in breakdown and utilization of stored nutrients
Sympathetic Ns is involved in breakdown and utilization of stored nutrients
32
Fasting Phase
- Fall in glucose level causes pancreas to stop secreting insulin and to start secreting glucagon
- Absence of insulin means most of cells of body can no longer use glucose
- All glucose present in blood is reserved for CNS
- Fat cells break down TAGs into FA and glycerol
33
Absorptive Phase: Glucose
- level of glucose in blood rises
- Activity of sympathetic NS to decrease and activity of parasympathetic NS to increase
- Tells pancreas to stop secreting glucagon and begin secreting insulin
- Insulin permits all cells of body to use glucose as fuel
- Extra glucose some is converted into glycogen which fills short-term carb reservoirs
- If glucose is left over, it is converted into fat and absorbed by fat cells
34
Absorptive Phase: Amino acids
- Small proportion are used to construct proteins and peptides
- Rest are converted to fats and stored in adipose tissue
35
Absorptive Phase: Fat
Stored in adipose tissue
36
Signals from Environment that start meal
- Time of day
- Presence of others
- Sensory signals, including sight or smell of food
37
Empty stomach and upper intestine (GI system) releases […] when digestive tract is empty
Empty stomach and upper intestine (GI system) releases ghrelin when digestive tract is empty
38
Ghrelin
Peptide hormone released by stomach that increases eating
- Produced by neurons in brain
- Binds to receptors in hypothalamus
- Increase with fasting and are reduced after meal
- Relays signals from stomach and digestive tract to hypothalamus
39
Prader-Willi Syndrome
Obesity caused by almost continuous eating
| - Chronic elevation in blood level of ghrelin, which remains high even after meal
40
Entry of food into […] suppresses ghrelin secretion
Entry of food into duodenum suppresses ghrelin secretion
41
Duodenum
First portion of small intestine, attached directly to stomach
- Contains ghrelin receptors
42
Hypoglycemia
Fall in blood glucose level is potent stimulus for hunger
43
Glucoprivation
Dramatic fall in level of glucose available to cells
| - Can be caused by fall in blood level of glucose or by drugs that inhibit glucose metabolism
44
Lipoprivation
Dramatic fall in level of fatty acid available to cells
| - Usually caused by drugs that inhibit fatty acid metabolism
45
2 sets of hunger detectors
- Brain receives glucoprivic hunger signal from liver through vagus nerve
- Lipoprivic hunger appears to be stimulated by receptors in liver
46
Brain contains detectors that monitor availability of […] inside BBB
Brain contains detectors that monitor availability of glucose inside BBB
47
Liver contains detectors that monitor availability of […] inside BBB
Liver contains detectors that monitor availability of nutrients inside BBB
48
After food reaches stomach it is mixed with […]
After food reaches stomach it is mixed with HCl and pepsin
49
Food is mixed with […], which continue digestive process
Food is mixed with bile and pancreatic enzymes, which continue digestive process
50
Duodenum controls rate of stomach emptying by secreting […]
Duodenum controls rate of stomach emptying by secreting cholecystokinin (CCK)
51
Cholecystokinin (CCK)
Hormone secreted by duodenum that regulates gastric motility and causes the gallbladder (cholecyst) to contract
- Appears to provide satiety signal transmitted to brain through vagus nerve
- Response to presence of fats
- Causes pyloris to constrict and inhibits gastic contractions
- Blood levels is related to amount of nutrients that duodenum receives from the stomach
- Doesn’t act directly on brain
52
Peptide YY3-36 (PYY)
Chemical produced by cells in GI tract and released by small intestine after meal in amounts proportional to calories that were just ingested
- Serves as satiety signal
- Amount of PYY released after meal correlates positively with people’s ratings of satiety
53
Hepatic Portal Vein
Vein that transport blood from digestive system to liver
- When liver receives nutrients from intestines, it sends signal to brain that produces satiety
- Signal continues satiety that was already started by signals from stomach and upper intestine
54
Ob Mouse
Strain of mice whose obesity and low metabolic rate are caused by mutation that prevents production of leptin
- OB gene normally produces leptin
55
Leptin
Hormone secreted by adipose tissue
| - Decreases food intake and increases metabolic rate, primarily by inhibiting NPY-secreting neurons in arcuate nucleus
56
Decerebration
Surgical procedure that severs brain stem, disconnecting hindbrain from forebrain
- brain stem controls chewing and swallowing behaviors
- Disconnects motor neurons of brain stem and spinal cord from neural circuits of cerebral hemispheres
- Can distinguish between different tastes
57
[…] are parts of medulla that receive taste info from tongue and variety of sensory info from internal organ
Area postrema and nucleus of solitary tract (AP/NST) are parts of medulla that receive taste info from tongue and variety of sensory info from internal organ
58
[…] hypothalamus regulates hunger while […] hypothalamus regulates satiety
Lateral hypothalamus regulates hunger while ventromedial hypothalamus regulates satiety
59
Orexigens
“Appetite-inducing chemicals”
- MCH and ore in
- MCH appears to play more important role in stimulating feeding
- Endocannabinoids stimulate eating by increasing MCH and ore in release
60
Arcuate Nucleus
Nucleus in base of hypothalamus that controls secretions of anterior pituitary gland
- Contains NPY-secreting neurons involved in feeding in control of metabolism
61
Paraventricular Nucleus (PVN)
Nucleus of hypothalamus located adjacent to dorsal third ventricle
- Contains neurons involved in control of ANS and posterior pituitary
62
Anorexigens
“Appetite- suppressing chemicals”
| - CART and a-MSH
63
Melanocortin-4 Receptor (MC4R)
Receptor found in brain that binds with a-MSH and AgRP
| - Plays role in control of appetite
64
PYY binds with an inhibitory autoreceptors found on […] neurons in […] of hypothalamus
PYY binds with an inhibitory autoreceptors found on NPY/AgRP neurons in arcuate nucleus of hypothalamus
65
Melanin-concentrating hormone (MCH)
Location of cell bodies: Lateral hypothalamus
Location of terminals: neocortex, PAG, reticular formation, thalamus, LC neurons in spinal cord that control sympathetic NS
Interaction with other peptides: Activated by NPY/AgRP; Inhibited by leptin and CART/ a-MSH
Physiological/ behavioral effects: eating; decreased metabolic rate
66
Orexin
Location of cell bodies: Lateral hypothalamus
Location of terminals: neocortex, PAG, reticular formation, thalamus, LC neurons in spinal cord that control sympathetic NS
Interaction with other peptides: Activated by NPY/AgRP; Inhibited by leptin and CART/ a-MSH
Physiological/ behavioral effects: eating; decreased metabolic rate
67
Neuropeptide Y (NPY)
Location of cell bodies: Arcuate nucleus of hypothalamus
Location of terminals:Paraventricular nucleus, MCH and orexin neurons of lateral hypothalamus
Interaction with other peptides: activated by ghrelin; inhibited by leptin
Physiological/ behavioral effects:eating; decreased metabolic rate; stimulates insulin and glucocorticoid secretion; decrease TAG breakdown; decreased body temperature
68
Agouti-related protein (AgRP)
Location of cell bodies: Arcuate nucleus of hypothalamus
Location of terminals:Paraventricular nucleus, MCH and orexin neurons of lateral hypothalamus
Interaction with other peptides: inhibited by leptin
Physiological/ behavioral effects:eating; decreased metabolic rate; acts as antagonist at MC4-R
69
Cocaine-and- amphetamine regulated transcript (CART)
Location of cell bodies: arcuate nucleus of hypothalamus
Location of terminals; paraventricular nucleus, lateral hypothalamus, PAG matter, neurons in spinal cord that control sympathetic NS
Interaction with other peptides: activated by leptin
Physiological/ behavioral effects: Suppression of eating; increased metabolic rate
70
a-Melanocyte Stimulating Hormone (a-MSH)
Location of cell bodies: arcuate nucleus of hypothalamus
Location of terminals; paraventricular nucleus, lateral hypothalamus, PAG matter, neurons in spinal cord that control sympathetic NS
Interaction with other peptides: activated by leptin
Physiological/ behavioral effects: Suppression of eating; increased metabolic rate; acts as agonist at MC4 receptors
71
Roux-en-Y gastric bypass (RYGB)
Produces small pouch is attached to lower portion of intestines
- Produce small stomach whose contents enter jejunum and bypass duodenum
- Can cause iron and Vit B12 deficiency
- Decreased ghrelin secretion
- Increased blood levels of PYY
72
Anorexia Nervosa
Disorder that most frequently afflicts young women
- Exaggerated concern with overweight that leads to excessive dieting and often compulsive exercising
- Can lead to starvation
73
Bulimia Nervosa
Bouts of excessive hunger and eating, often followed by forced vomiting or purging with laxative
74
Binge-Eating Disroder
Disorders that includes bouts of excessive eating
75
Sensation of thirst involves [...]
Sensation of thirst involves anterior cingulate cortex
76
Osmosensory transduction occurs in [...]
Osmosensory transduction occurs in magnocellular neurosecretory cells (MNCs)
77
Subfornical Organ and Thirst
small organ located in confluence of lateral ventricles, attached to underside of the fornix
78
Neurons in the SFO send their axons to [...]
Neurons in the SFO send their axons to median preoptic nucleus
79
Median Preoptic Nucleus
small nucleus wrapped around the front of anterior commissure, a fiber bundle that connects amygdala and anterior temporal lobe
80
Satiety Signals
- Short-Term: entry of food into stomach; nutrient detectors activated
- Long-Term: arise in the adipose tissue (long-term nutrient reservoir)
81
Liver Satiety Signals
- Last stage of satiety
- Nutrient detectors in liver send signal after nutrients received from intestines
- Glucose and fructose through hepatic portal vein there was reduction of food intake
- Fructose can't cross BBB and is metabolized poorly by cells in rest of the body
82
Reinforcement, Stress, and Food
DA and CRH involved in relapses of addictive behaviors
83
Pharmacological Interventions for Obesity
- Fenfluramine- serotonin agonists
| - Rimonabant
84
Fenfluramine- serotonin agonists
pulmonary hypertension and damage to heart valves
85
Rimonabant
blocks CB1 receptors
- suppresses appetite, weight loss, increases HDL
- more depressive moods, anxiety, and suicide risk
