Endocrine control of appetite: satiety and hunger Flashcards
Health risks of obesity
Heart disease
Stroke
Metabolic syndrome
Fatty liver diseases
Some cancers
Breathing problems
Osteoarthritis
Gout
Diseases of the gallbladder and pancreas
Kidney disease
Pregnancy problems
Fertility problems
Sexual function problems
Mental health problems
Environmental/societal factors impacting obesity
Biological factors impacting obesity
Many, but focus on:
Signals from the adipose tissue, pancreas, liver, and git
nb - paper on physiology of hunger will be on canvas
Hunger (homeostatic)
the physiological impulse to eat that is triggered by starvation (acute energy deprivation) in order to maintain energy balance
Appetite
hedonic hunger
food intake driven by pleasure rather than by metabolic necessity
The “thrifty genotype” hypothesis
Evolutionary pressure favours genes promoting weight gain, i.e. efficient storage of ingested calories when access to food is unreliable
Blood brain barrier (BBB)
Made up of endothelial cells (cells that line blood cells), which are often semi-permeable but in this case are really tight <- deliberate to prevent brain infections. 2 places where the barrier is more semi-permeable: the hypothalamus and medulla oblongata
Sagitall view
if the brain is cut kinda like through the nose?
Nucleus in the context of the hypothalamus
really small sub areas, not a cell nucleus
transverse view
cutting the brain across a horizontal plane. I’m pretty sure
Control centre for appetite regulation
Hypothalamus
Lesion
a region in an organ or tissue that has suffered damage through any one of a range of ways
Paravemtricular hypothalamic nuclei (PVM)
Legions to this area damages satiety sensing and leads to overeating (seen in rats)
Lateral hypothalamic nucleus
lesions here lead to no hunger (seen in rats)
How is eating controlled?
Stomach wall stretch receptors
Glucose lipid levels detected in intestines
Stomach and gut release hormones
Stomach wall stretch receptors
signal distention as food fills the stomach. = > afferents of the vagus nerve => solitary nucleus of the medulla = > hypothalamus
Glucose lipid levels detected in intestines
=> sensory afferents => solitary nucleus of the medulla = > hypothalamus.
Stomach and gut release hormones
CCK, Peptide YY, Glucogon-like peptide -1 (GLP-1) and ghrelin. => hypothalmus & other areas (area postrema, medulla)
Lectin
Hormone makes you feel full
Grehlin
Hormone that makes you feel hungry
wtf is going on with these mice
THEY SURGICALLY ATTACHED THEM WTF
Why did obese mouse attached to wild type mouse become healthy?
lectin began to circulate both
but also WHAT
Where is leptin released from?
Adipose tissue
(Sometimes referred to as adipocytokine bc it is structurally similar to cytokines)
High levels of leptin
inhibit food intake, stimulate catabloic process including loss of fat
low levels of leptin
increases food intake, stimulate anabolic processes, process fat tissue builds up
Where does leptin signal?
Hypothalamus -arcuate nucleus neurons
Leptin stimulates neurons that expressed proopiomelanocortin (POMC) and cocaine and amphetamine-related transcript (CART)
Leptin inhibits neurons that express neuropeptide Y (NPY) and agouti-related peptide (AgRP)
Insulin is a ? term hormone
short
Leptin is a ? term hormone
long
Why does leptin not work for an obesity treatment?
Obese individuals have high levels of leptin and have developed leptin resistance
Gut-brain signalling
hormones sensing the presence and absence of gut contents
Hormones indicating the presence of food
CCK
GIP
CLP-1&2
PYY
Neurotensin
Hormones indicating the absence of food
Grehlin
Where is ghrelin produced?
cells in the fundus of the stomach
Acylated peptide
potent orexigenic activity
Outcome of ghrelin signalling
increases appetite and may serve as a signal to co-ordinate nutrient acquisition with growth
Ghrelin patterns
plasma levels rise 1-2 hrs before normal meals and falls to minimum 1h after eating
How does Ghrelin stimulate food intake?
Reacts with its receptor in hypothalamic neurons that express NPY
