Lecture 5: Homeostasis, Metabolism & Eating Disorders Flashcards

(67 cards)

1
Q

homeostasis

A

the maintenance of an internal stable environment within the body, despite the changing external environment
- e.g. body temperature, glucose level, oxygen level, blood pressure

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2
Q

gastrointestinal tract

A

the part of the digestive tract where food is broken down and absorbed so that the nutrients can be mobilized and used as energy sources

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3
Q

eating habits before eating

A
  • prior to the act of eating, the body begins the digestive process
  • once the food is in the mouth, saliva and chewing are used to prepare the food to be swallowed
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4
Q

eating habits during eating

A
  • chewed food is formed into a moist ball (bolus), and enters the oesophagus and is collected in the stomach
  • hydrochloric acid breaks down the food
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5
Q

eating habits after eating

A
  • pepsin initiates the breakdown of protein molecules into amino acids
  • stomach empties through the pyloric sphincter, slowly into the duodenum
  • enzymes from the gallbladder and pancreas are added to the food pulp
  • division into smaller particles allows the elements to be small enough to pass through the lining of the duodenum into the bloodstream
  • once in the bloodstream, they are processed by the liver
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6
Q

emulsification

A

fats are broken down by bile, which is made by the liver and stored in the gallbladder
- fat molecules won’t pass through the wall of the duodenum, and therefore transported through small tubes in the lymphatic system

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7
Q

lipids

A

fatty acids or derivatives thereof
- insoluble in water

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8
Q

amino acids

A

simple organic compounds that compose protein when assembled into long chains

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9
Q

glucose

A

a sugar and energy source
- a simple sugar broken down from carbohydrates

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10
Q

where energy is stored

A
  • fats (main storage system)
  • glycogen (converted to glucose): a substance deposited in body tissues as a store of carbohydrates
  • proteins
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11
Q

three processes/phases in energy metabolism

A
  • cephalic or reflex phase
  • gastric or absorption phase
  • intestinal or fasting phase
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12
Q

cephalic or reflex phase

A

involves preparatory processes for feeding, in which the sensory stimulus for food activates the digestive system
- the cephalic phase stops when nutrients are absorbed into the bloodstream

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13
Q

gastric or absorption phase

A

occurs when the body’s immediate needs are attended to and nutrients are absorbed into the bloodstream
- takes 3-4 hours
- the physical relaxation caused by food in the stomach activates stretch receptors that promote the parasympathetic version of ACh
- ACh increases the secretion of gastric juices
- increasing pH stimulates the release of gastrin by enero-endocrine cells

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14
Q

gastrin

A

a peptide hormone that causes the stimulation of hydrochloric acid (HCL)
- HCL creates an acidic environment for protein digestion
- also responsible for smooth muscle contractions and the movement of food

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15
Q

enero-endocrine cells

A

specialized cells of the endocrine system located in the gastrointestinal tract and pancreas

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16
Q

intestinal or fasting phase

A

occurs when nutrients no longer provide immediate energy and the body mobilizes previously stored nutrients
- end of the fasting phase precedes the beginning of the cephalic phase

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17
Q

insulin

A

an important hormone in the digestive process

released by the pancreas for:
- the use of glucose
- the conversion of glucose to glycogen and fat for storage
- the conversion of amino acids into proteins for storage
- the storage of glycogen in the liver and muscles
- the storage of fat in adipose tissue
- the storage of proteins in the muscles

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18
Q

glucagon

A

a peptide hormone released by the pancreas when glucose levels become lower
- converts stored glycogen into glucose
- promotes the release of fatty acids from adipose tissue and stimulates the conversion of these fatty acids into ketones

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19
Q

ketones

A

used by muscles as an energy source

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20
Q

satiety

A

the feeling of being full

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21
Q

vagus nerve

A

connects the digestive system to the neural system
- transmits the focus of eating behavior to the brain

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22
Q

biomolecules

A

molecules derived from substances that occur naturally in an organism
- e.g. amino acids, triglycerids, and glucose

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23
Q

catabolism

A

the breakdown of complex molecules to release energy

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24
Q

disaccharide

A

a molecule made up of two monosaccharides
- e.g. sucrose (table sugar) made up of glucose and fructose

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25
anabolism
the creation of complex molecules from simple ones to store energy
26
glycogen
a multiple-branched polymer of glucose, which serves as energy storage in animals - polysaccharide
27
storage of fats
in the cytoplasm of body cells - the tissue in which fat is stored is called adipose tissue
28
lipoproteins
transport units for fats secreted by the liver - a combination of protein, triglycerides, and cholesterol in a phospholipid membrane
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catabolized units
when glycerol and fatty acids are attached together forming a long chain
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anabolized
when phospholipids (membrane) and triglycerides (body fat) are attached together
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cholesterol
promotes cell membrane fluidity and can be metabolized into steroid hormones, such as estrogen
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LDL (low-density lipoprotein) and HDL (high-density lipoprotein)
ratio between them is important for cardiovascular health, as LDL promotes plaque formation in cell walls
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lipogenesis
the making of fats
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absorptive state
glucose can be stored as glycogen, used for energy, or adipose tissue can convert glucose into fats (lipogenesis) - fatty acids are taken up by adipose tissue and combine with a-glycerol phosphate to form triglycerides
35
post-absorptive state
the body is in this phase after 4 hours without food - glycogenolysis - gluconeogenesis
36
glycogenolysis
occurs when glucose is released from glycogen - can be in the liver or the muscles
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gluconeogenesis
new glucose is generated from amino acids or fats - during this phase, there are high values of glucagon and low values of insulin
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cellular respiration
glucose is eventually converted into ATP in a cell - requires oxygen and water - delivers ATP, heat, and CO2
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hypoglycemia
when glucose levels in the blood are low
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A-cells and B-cells
- A-cells add glucose to the bloodstream via glucagon - B-cells bring down glucose levels via insulin
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hypothalamus
made up of separate nuclei - lateral hypothalamus (LH) and the ventromedial hypothalamus (VMH) emphasized in relation to hunger - LH considered the hunger center - VMH considered the satiety center
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lesions of the ventromedial hypothalamus (VMH)
lesions of the VMH is rats let to hyperphagia (overeating)
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2 types of hyperphagia
- dynamic phase: during which the rats gained most of their weight, which occurred immediately after surgery - static phase: during which the rats ate enough to become obese
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lesions of the lateral hypothalamus
caused aphagia in rats and cats: they stopped eating - accompanied by adipsia: they stopped drinking
45
glucoreceptors
receptors for glucose in the VMH
46
2 areas of the brain which stand out in motivational eating behaviors
ventral tegmental area (VTA) and nucleus accumbens (NAcc) - dopamine is released in these areas when primary reinforcers are presented - food, a primary reinforcer and essential for survival, increases dopamine outflow from the NAcc
47
anorexia nervosa
a condition of restricted food intake, leading to severe weight loss - occurs mainly in women - strive for a body image that they often see on social media
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regions playing important role for anorexia
insula and cingulate cortex
49
cingulate cortex
underlies motivation, goal-directed behavior, and emotional processes
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insula
involved in emotion and disgust - considered the central mechanism uderlying anorexia nervosa
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serotonin and dopamine in anorexia patients
serotonin and dopamine levels are reduced among anorexia patients, which may be linked to changes in motivation and reinforcement - main treatment drug is SSRIs
52
bulimia nervosa
patients with bulimia nervosa binge eat and then purge by vomiting or laxatives to control their weight - fluoxetine (Prozac) is a 5-HT agonist used to treat bulimia nervosa
53
metabolic rate
the speed at which the body uses energy to perform basic functions
54
average kcal requirement for men and women
- 2500 kcal for men - 2000 kcal for women
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basal metabolic rate (BMR)
the amount of energy expressed in calories that a person needs to maintain body functions at rest
56
leptin
a hormone that suppresses the feeling of hunger
57
hypothyroidism
insufficient thyroid hormone - associated with fatigue, depression, libido loss, a decreased metabolic rate, and a slower heart rate (bradycardia) - anorexia nervosa is related to hypothoyroidism
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hyperthyroidism
too much thyroid hormone - related to hyperactivity, insomnia, libido loss, an increased metabolic rate, and a faster heart rate (tachycardia) - adrenaline can have a diminished function
59
2 fluid-filled compartments in the body
intracellular fluid (in the cytoplasm) and extracellular fluid - include intravascular fluid (blood plasma), interstitial fluid (between cells) and cerebrospinal fluid (CSF)
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types of thirst
- osmotic thirst - hypovolemic thirst
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osmotic thirst
occurs when the dissolved concentration of extracellular fluid increases, triggered by loss of volume in the intracellular fluid stores - it becomes saltier and absorbs water from the intracellular fluid, which can compromise cells)
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osmoreceptors
possibly located in the anterior hypothalamus and other areas, detect changes in the concentration of interstitial fluid
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hypovolemic thirst
occurs when intravascular fluid decreases - a loss of blood volume is detected by baroreceptors and also by receptors in the kidneys
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renin
secreted by the kidneys during times of low blood flow - helps the production of angiotensin
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angiotensin
a hormone that increases drinking - activates 2 other hormones: aldosterone and vasopressin
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aldosterone
retains salt and water, and constricts blood vessels
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vasopressin
reduces the amount of fluid going to the bladder - conserves water, while aldosterone conserves salt until more is consumed