Exam 3: Disorders of Nutrition

Question 1

what are the functions of adipose tissue? (3)

Answer 1

o Insulation
o Mechanical support
o Energy reserve, to fuel other tissues

Question 2

where is white adipose tissue (WAT) found?

Answer 2

 Located in visceral and subcutaneous tissue, most adipose tissue in our body

Question 3

what hormones are WAT mostly subject to?

Answer 3

-estrogen
**men dont have a lot of estrogen so they have more fat around the waist
**post-menopausal women after estrogen level decrease tend to get more centrally adipose/fat

Question 3

what does WAT contribute to?

Answer 3

 contributes to energy homeostasis
* where we store energy and burn when we need it

Question 4

what does WAT endocrine organ consist of? and what are its functions?

Answer 4

• Adipocytes
  o “Fat storing cells, stores it in form of triglycerides, synthesize triglycerides from glycose, and mobilize energy in the form of free fatty acids and glycerol”
• Adipokines: hormones
  o Function in control of food intake, can help lipid storage, insulin sensitivity, immune and inflammatory responses, coagulation, fertility vascular homeostasis, blood pressure regulation, bone metabolism
  o Excess WAT causes dysregulation of adipokines, contributes to comorbidities of obesity

Question 4

what does it mean when you have more leptin in your body

Answer 4

more inflammation in body

Question 4

what kind of organ is WAT?

Answer 4

 Endocrine organ: can be endocrine, autocrine, or paracrine

Question 4

what adipokines are increased in obesity (bad)? (6) and what are their functions?

Answer 4

o Angiotensinogen, angiotensin 1 and type 1 receptors, Renin, ACE
 Promotes vasoconstriction
 Promotes inflammation
 Promotes lipogenesis
 Increases insulin resistance

o Leptin (Primarily from Subcutaneous WAT) [Leptin Resistance]
 Inhibits appetite and stimulates energy expenditure
 Promotes satiety (hunger/appetite suppression) and regulation of eating behavior by hypothalamus
 Promotes sympathoactivation
 Is insulin sensitizing in liver and skeletal muscle
 Plays a modulating role in reproduction, angiogenesis, immune response, blood pressure control, osteogenesis
 Promotes inflammation

Question 5

what adipokines are decreased in obesity? (good)?

Answer 5

o Adiponectin
 Is insulin sensitizing
 Is anti-inflammatory
 Is antiatherogenic–decrease the deposition of LDL

Question 6

explain WAT in chronic positive energy balance

Answer 6

• Hyperplasia then hypertrophy
• Visceral WAT hypertrophy, leads to;
  o insulin resistance, pro-inflammatory, altered lipids, renin and angiotensin
   diabetes, cancer, atherosclerosis, NAFLD/NASH, HTN
• Excessive hypertrophy
  o exceeds supporting vascular supply, lipotoxicity, cell necrosis (increase in inflammation)
   cell getting bigger and bigger can become toxic

**chronic positive energy state =takes in more calories than its burned off

Question 7

white adipose tissue physiologic functions (10)

Answer 7

• vascular tone control
• coagulation
• immunity
• appetite regulation
• glucose and lipid metabolism
• reproductions
• angiogenesis
• fibrinolysis
• body weight homeostasis
  -Mental health (depression, mood disorders, memory/cognition)

Question 8

describe Brown Adipose Tissue (BAT)

Answer 8

 Less metabolically active
 Located in the interscapular, perirenal, supraclavicular, paravertebral regions
 Rich in mitochondria, contains iron (brown color), multiple lipid droplets, inverse relationship with BMI and age (if you have more BAT, less likely to be overweight)
* Most common location for lean humans- neck, supraclavicular, axillary, paravertebral, perineal areas
 Generates body heat- helps newborns stay warm
* Exposure to cold, activation of the sympathetic nervous system and catecholamines, and activation of triiodothyronine (T3) stimulate BAT to rapidly generate heat

Question 9

describe Beige AT (bAT): Beige Adipose Tissue

Answer 9

 “Brown in white”
 Develops within WAT with chronic exposure to cold, exercise, exposure to synthetic ligand of peroxisome proliferator activated receptor-y (PPARy) or thiazolinediones (TZD)
* Leptin and insulin together promote bAT, increasing energy expenditure and weight loss.
* bAT is diminished in obesity (not good)
 Reverts to WAT with warm adaptation
 Increasing bAT is promising for obesity treatment

Question 10

List and summarize how other medical conditions are related to obesity

Answer 10

o Cushing’s syndrome, PCOS, growth hormone deficiency, hypothyroidism
o Physical inactivity and genetic predisposition
 Increase size and number of adipocytes usually in visceral, liver, and muscle
 Leads to alterations in adipokines, hormones, and fat cells themselves
 Leads to insulin resistance, inflammation, and increase in very low LDL in blood -> arteries
* Alterations in the WAT hormones result in obesity mostly related to the altered hormone responses

Question 11

define obesogens

Answer 11

o Exogenous chemicals that stimulate the development of fat, contribute to the development of obesity, disrupt hormone signals, cause hyperplasia and hypertrophy
 Interfere with neuroendocrine control of appetite and satiety.

Question 12

describe routes of exposure to obesogens

Answer 12

o These chemicals cross placenta and in breast milk, passed through generations
 i.e. Phytoestrogens, pesticides, plastics, personal care products, household cleaners, medications, chemicals in our environment

Question 13

Explain how leptin resistance promotes obesity

Answer 13

o Leptin is a hormone released from fat
o inhibits appetite and promotes satiety
o Stimulates energy expenditure (means you’re full and have enough stores of energy and you can use it), insulin sensitizer, promotes inflammation
o Normal fed state- high levels of leptin act on the hypothalamus to inhibit orexigenic neurons and stimulate the anorexigenic neurons to suppress appetite.
o Leptin # increase as adipocytes increase, however high leptin levels are ineffective at decreasing appetite and energy expenditure, condition known as leptin resistance
o In obesity- usually high levels of leptin but body can’t sense it therefore increases inflammation

Question 14

what does leptin resistance mean? (3) and what happens?

Answer 14

• defect in transport
• inability to cross BBB
• receptor defect
  probably have high levels of leptin but body cant sense it
  leptin isnt able:
• to suppress appetite
• regulate hepatic gluconeogenesis or glucose and lipid metabolism
• sensitize to insulin

Question 15

what is the function of the hypothalamus?

Answer 15

o Hypothalamus regulates food intake and energy metabolism.
o Hypothalamus controls reward, pleasure, memory and addictive behavior- it can override what hormones say.

Question 16

what occurs in the hypothalamus can contribute to obesity?

Answer 16

o Alterations in the expression of hormones and neurotransmitters, affecting appetite and metabolic rate at the level of the hypothalamus contribute to obesity!

Question 17

what are Orexigenic neurons

Answer 17

• promote appetite, stimulate eating, and decrease metabolism

Question 18

what are Anorexigenic neurons

Answer 18

• suppress appetite, inhibit eating, and increase metabolism

Question 19

Summarize the factors that contribute to the anorexia of aging

Answer 19

o Decrease in appetite due to-
 reduced energy needs, waning hunger diminished sense of taste and smell, decreased production of saliva, altered GI satiety mechanisms, co-morbidities, meds
o Decreased orexigenic and increased anorexigenic signals
o delayed gastric emptying, decreased small intestine motility, sensory impairments, medical/psych disorders, social isolation, abuse, neglect