Neuroscience Flashcards
metabolic comorbidities of obesity: (9 points)
- asthma
- NAFLD
- gallstones
- infertility
- cancers
- cardiovascular disease
- type 2 diabetes
- thrombosis
- gout
mechanical comorbidities of obesity: (5 points)
- impaired physical functioning
- urinary incontinence
- arthrosis
- sleep apnoea
- chronic back pain
what are the 3 parts of the appetite control system
- Sensory INPUT
Sight, smell, sound, taste, touch
Nutrient signals generated from pre-ingestion to oxidation - Neural INTEGRATION
Bottom-up and top-down - Appetitive OUTPUT
Behavioural (motor)
Autonomic & endocrine
the 2 elements of the energy balance equation (EBE)
intake:
-hunger & satiety
-hedonics
-nutrient absorption
expenditure:
-metabolic rate
-thermogenesis
-activity
the 5 components of appetite
Hunger:
-the drive to consume
Wanting (craving):
-motivation to consume a specific food
Liking (hedonic):
-sensory pleasure elicited from contact with food
Satiation:
-negative feedback, leading to meal termination (within-meal inhibition)
Satiety:
-end state of satisfaction (between-meal inhibition)
hormones that control energy balance
-insulin
-leptin
-ghrelin
Hormones: stomach
- Release of Ghrelin the hunger hormone suppressed by carbohydrate, fat and protein
- gastrin - produced in the stomach when it is stretched.
Hormones: duodenum
Cholecystokinin (CCK) released in response to protein and free fatty acids
(duodenal brake)
CCK stimulates the gallbladder to contract and release stored bile into the intestine
Hormones: ileum
GLP-1 released in response to carbohydrate and fats and influenced by fibres
(Ileal brake)
It has the ability to decrease blood sugar levels by stimulating insulin secretion and inhibiting glucagon secretion
Hormones: colon
Peptide YY (PYY) released in response to carbohydrate and fat and influenced by fibres
PYY acts on NPY receptors and inhibits gastric motility, increases water and electrolyte absorption in the colon, and may suppress pancreatic secretion
How does stored energy feedback to the CNS to alter subsequent eating behaviour, and maintain weight / energy balance?
Leptin (leptos -‘thin’) - protein produced by adipose tissue (the body’s fat stores) when ‘full’.
Leptin is a potent reducer of food intake and Leptin appears act as a natural adiposity (body fat) signal
leptin binds to ‘leptin receptors’ in the hypothalamus, which:
- suppresses appetite
- increases the metabolic rate
- stimulates thermogenesis
what was the finding of the study on obese mice?
Obese mice (ob/ob) could not produce leptin because they were born without required gene code. Once the leptin producing gene was identified is was termed the ob-gene.
Congenital Leptin Deficiency
In humans there is a rare condition in which, due to a single gene defect, leptin cannot be produced.
Children demonstrate excessive weight gain and various appetites.
Administration of recombinant leptin completely reverses this condition
what was Eliot Stelar’s dual centre theory? (1950s)
lateral hypothalamus (LHA) as ‘hunger centre’
ventromedial hypothalamus (VMN) as ‘satiety centre’
activity influenced by circulating glucose & lipids etc
What do new CNS Integrations of Appetite Control
theories focus on
neuropeptides, produced & released by arcuate (ARC) regulate other hypothalamic & extra-hypothalamic areas
and
are themselves regulated by a host of peripheral feedback signals (CCK, GLP-1, Leptin
CNS structures involved in appetite regulation
-Arcuate Nucleus (ARC)
-Ventro Medial Hypothalamus (VMH)
-Lateral Hypothalamus (LH).
-Paraventricular Nucleus (PVN).
The arcuate nuceus (ARC) is the source of two major neuropeptide systems involved in appetite regulation
Neuropeptide Y system (NPY) – appetite stimulation (Orexigenic)
Melanocortin system (αMSH) – appetite inhibition (Anorexigenic)
what is Orlistat?
pancreatic lipase inhibitor that reduces fat absorption from gut produces modest weight loss, (unpleasant GI side-effects, only effective with high fat diets…)
what does ‘Bupropion and Naltrexone’ do?
Bupropion stimulates the release of the MC4R agonist αMSH from the POMC neurons in the PVN
Naltrexone preventsinhibition of POMC neurons by blocking the action of β-endorphin potentiating Bupropion effects
improves control over eating
what does Liraglutide and Semaglutide do?
GLP-1 analogues enhance satiety and reduce energy intake
6 biological changes in aging:
- Immune system: Increase susceptibility to infection.
- Cardiovascular system: Inc size and weight of heart, inc collagen in blood vessels, hardening of the blood vessels and change in blood pressure.
- Respiratory system: Decrease lung capacity – alveoli decrease in efficiency
- Musculoskeletal system: Reduction in muscle mass and strength, loss of bone matrix.
- Gastrointestinal system: Decreased blood flow to gut and liver and decreased absorption of GI tract.
- Integument: Graying of hair, wrinkling of skin, decrease in melanin.
what is corneal flattening?
In the aging eye the corneal surface flattens, admitting less light into the eyeball. This change reduces the transmitted light into the elderly eye by one third.
what happens to the lens with age? and how does this affect vision?
The transparency of the lens actually diminishes with aging which weakens available light to receive colors with short wavelengths such as blue and violet. When new lens fibers naturally multiply at the edge of the lens, older fibers move to the center to create a dense center of the lens.
Over time, the lens accumulates yellow substances which filter out the blue part of the color spectrum. Blue actually appears more green. Warmer colors like reds and oranges, seem stronger in comparison.
how is the retina affected with age? and how does this affect vision?
The most sensitive part of the retina gradually functions less well with age due to decreased blood supply and the cumulative effects of radiation damage.
The result is decreased spatial discrimination, black and white contrast, and flicker sensitivity.
You become less able to tolerate glare and have more trouble adapting to darkness or bright light.