Chapter 16: Motivation Flashcards
What is the state called when blood is filled with nutrients?
Prandial state.
In which two forms is energy stored during the prandial state?
Glycogen and Triglycerides.
The assembly of macromolecules such as glycogen and triglycerides from simple precursors is called….?
Anabolism or anabolic metabolism
What is the fasting condition between two meals called?
Postabsorptive State.
The process of breaking down complex macromolecules is called….?
Catabolism or catabolic metabolism.
All cells can use……. to get energy but neurons only can use….. to get energy.
Glucose, Fatty acids, Ketones.
Neurons can only use Glucose.
What does the lipostatic hypothesis say?
Brain monitors the amount of body fat and acts to defend this energy store against perturbations.
Which cells release leptin and with what does this hormone communicate to regulate what?
Adipocytes (fat cells) release leptin which regulates the body mass by acting on neurons in the hypothalamus that decrease appetite and increase energy expenditure.
What is the probem with ob/ob mice?
They lack the gene responsible to generate leptin. Because of this lack of leptin their brain is fooled into thinking that fat reserves are low thus they are motivated to overeat.
What is the lateral hypothalamic syndrome?
Anorexia caused by a damage to the lateral hypothalamus.
What is the ventromedial hypothalamic syndrome?
Overeating and obesity caused by lesions to the ventromedial hypithalamus.
To receptors of which part of the Hypothalamus does leptin go? What happens next?
Adipocytes release leptin which travels to receptors of the arcuate nucleus of the hypothalamus. Then arcuate neurons are activatet they posess aMSH and CART.
What is the humoral response of the body to high leptin levels or excessive adiposity?
The two piutitary hormones thyroid-stimulating hormone TSH and adrenocorticotropic hormone ACTH are increasingly secretet. They act on the Thyroid glands and the adrenal glands and have the effect of raising the metabolic rate of cells throughout the body.
What is the visceromotor response to high leptin levels?
The visceromotor response increases the tone of the sympathetic division of the ANS which also raises metabolic rate in part by raising body temperature.
The humoral response to high leptin levels is triggered by neurons of which part of the hypothalamus?
Paraventricular neucleus which in turn causes the release of hypophysiotropic hormones that regulate the secretion of TSH and ACTH
What does the injection of alpha-melanocyte-stimulating-hormone and cocaine-amphetamine-regulated-transcript into the brain cause and what are they called to be because of that?
The injection of aMSH and CART into the brain mimics the response to elevated leptin levels. So they are called anorectic peptides because they diminish appetite.
What happens if one takes drugs that inhibit the action of aMSH and CART?
Increase of feeding behavior.
When the leptin levels are low another typ of neurons are activated in the arcuate nucleus. Which peptides do they release and what do they cause?
NPY and AgRP inhibit the secretion of TSH and ACTH. They activate the parasympathetic division of the ANS and stimulate feeding behavior. They are calle orexigenic peptides.
What are AgRP and aMSh to each other?
They are antagonistic. Both bind to the MC4 Receptor.
Leptin levels rise when…. ?
Body fat is increased.
Leptin levels fall when….?
body fat is decreased.
What do orexigenic peptides do?
Stimulate feeding behavior.
Name four orexigenic peptides with location.
NPY - Neuropeptide Y - Arcuate Nucleus
AgRP - Agouti-related peptide - Arcuate Nucleus
MCH - Melanin-concentrating hormone - Lateral hypothalamic area
Orexin- Lateral hypothalaic area
Name two anorectic peptides what do they do and where are they located?
Anorectic peptides act one the brain to inhibit feeding behavior and increase metabolism.
aMSH - alpha-melanocyte-stimulating-hormone - Arcuate Nucleus
CART - Cocaine-and-amphetamine-regulated transcript - Arcuate Nucleus
What does ghrelin stimulate?
Appetite and food consumption by activating the NPY- and AgRP-containing neurons of the arcuate nucleus.
Name three satiety signals.
Gastric Distension
Cholecystikinin (CCK)
Insulin
What did studies about electrical self-stimulation show? What showed the injection of amphetamine?
Researchers could show that the most effective sites in the brain for self-stimulation fell along the trajectroy of dopaminergic axons arising in the ventral tegmental area and projecting in the forebrain.
Animals will press a button to get an injection of amohetamine which will release dopamine.
In General: Dopamine release in the brain will reinforce the behavior that causes it.
When is serotonin level low? When does it rise? When does it peak?
Low during postabsorptive state
Rises in anticipation of food
Spikes during a meal
With which neurotransmitter are the mood-elevating effects of eating are believed to be related?
Serotonin.
Describe the Cephalic phase.
Sight and smell of food trigger (in anticipation) physiological processes such as:
Parasymathetic and enteric division of the ANS are activated causing secretion of saliva and digestive juices in stomach
Describe the Gastric Phase.
The physilogical responses occuring during cephalic phase get much stronger when chewing, swallowing and filing stomach with food
Describe the Substrate phase
Nutrients begin to be absorbed into the blooodstream
Ghrelin is highly concentrated in the stomach. When is it released into the bloodstream?
When the stomach is empty
What is gastric distension?
It is a satiety signal. Mechanoreceptor detect distension they ascend via the vagus nerve to the brain.
What does cholecystokinin do?
Satiety signal. It is stimulated by certain types of food especially fatty ones. CCK acts together with gastric distension (vagus nerve)
What is insulin?
Released into blood by beta cells of the pancreas.
Glucose transport into cells (except neurons) requires insulin
It is important for anabolism
Blood glucose levels are elevated when…?
insulin levels are reduced
Blood glucose levels fall when…
insulin levels rise.
Thirst triggered by hypovolemia is called…?
volumetric thirst
Name two physiological signals that trigger drinking behavior.
hypovolemia: decreased blood volume
hypertonicity: increase in concentration of dissolved substances
Vasopressin acts directly on the kidneys to….?
increase water retention and inhibit urine production
The release of vasopressin associated with volumetric thirst is triggered by which two stimuli?
Rise in blood levels of angiotensin II occurs due to reduced blood flow to the kidneys. Angiotensis II travels to the subfornical organ where it causes Vasopressin release.
Mechanoreceptors in the walls of major blood vessels and heart signal loss of blood pressure. These signals make their way to the hypothalamus
Hypertonicity is sensed by…?
Vascular organ of the lamina terminalis
The vascular organ of the lamina terminalis OVLT activates…?
magnocellular neurosecretory cells (causing secretion of vasopressin) and cells in the lateral hypothalamus (causing osometric thirst)
Diabetes insipidus ist caused by…?
selective loss of vasopressin-secreting neurons
The most important neurons for temperatur homeostasis are found…
clustered in the anterior hypothalmus
Name humoral response, visceromotor response and somatic motor response to…a rise of temperatur.
TSH release is reduced
Parasympathetic activity is increased
pantintg, seeking cold
Name humoral response, visceromotor response and somatic motor response to…a fall of temperatur.
TSH release is increased
Sympathetic activity is increased
shivering; seeking warmth
