NEUR 0010 - Chapter 16 Flashcards
What are the three components of the hypothalamic response to regulate homeostasis?
Humoral response, visceromotor response, and somatic motor response
What is the humoral response of the hypothalamus to homeostasis?
Hypothalamic neurons stimulate or inhibit the release of pituitary hormones
What is the visceromotor response of the hypothalamus to homeostasis?
Hypothalamic neurons adjust the balance of SANS and PANS
What is the somatic response of the hypothalamus to homeostasis?
Hypothalamic neurons incite appropriate motor behavioral response
How is energy stored in the prandial state?
Glycogen and triglycerides
Where are glycogen and triglycerides stores?
Glycogen in the liver and skeletal muscle; triglycerides in adipose tissue
What is anabolism?
The assembly of glycogen and triglycerides from simple precursors
What is the postabsorptive state?
Stores glycogen and triglycerides are broken down to provide the body with continuous energy like glucose, fatty acids, ketones, etc.
What is catabolism?
The process of breaking down complex molecules
Where are the hypothalamic cells that detect a drop in leptin?
Periventricular hypothalamus
Where are the neurons that incite feeding behavior?
Lateral hypothalamus
What is leptin?
A protein released by adipocytes, coded by the ob gene; regulates body mass by acting directly on neurons of yhe hypothalamus that decrease appetite and increase energy expenditure
What is lateral hypothalamic syndrome?
Causes lack of appetite; anorexia
What is ventromedial hypothalamic syndrome?
Causes overappetite and overeating; obesity
What parts of the hypothalamus are the hunger vs satiety centers?
Hunger center = lateral; Satiety center = ventromedial
What is the arcuate nucleus?
In the hypothalamus: contains leptin receptors
What two NTs characterize arcuate nucleus neurons?
Alpha MSH and CART
What is the body’s response to high leptin?
Humoral response (increased TSH and ACTH secretion to raise metabolic rate); Visceromotor response (increases SANS tone to raise metabolic rate); Somatic motor response (decreases feeding behavior)
What triggers the humoral response to high leptin?
Activation of the paraventricular nucleus: causes release of hypophysiotropic hormones that stimulate release of TSH and ACTH from the anterior pituitary
What triggers the visceromotor response to high leptin?
Activation of the paraventricular nucleus: affects the SANS to the lower brain stem and spinal cord; AND arcuate nucleus direct path: alphaMSH and CART neurons project into intermediolateral gray matter of the spinal cord
What triggers the somatic motor response to high leptin?
Feeding behavior inhibited via connections of acruate nucleus neurons with cells in the lateral hypothalamus
What are two anorectic peptides?
alphaMSH and CART: mimic response to elevated leptin levels; diminish appetite
Low leptin triggers release of what two molecules?
NPY and AgRP
What are NPY and AgRP?
Peptides released by the arcuate nucleus; in response to low leptin, DECREASE the secretion of TSH and ACTH (lower metabolic rate) and activate PANS
What are two orexigenic peptides?
NPY and AgRP
What part of the hypothalamus is responsible for feeding behavior?
Lateral hypothalamic area
What is MCH?
Peptide hormone in the lateral hypothalamic area cells; informs the cortex of leptin levels in the blood, and motivates the search for food
What is orexin?
Peptide in the lateral hypothalamic area cells: rise in the brain when leptin blood levels falls
What is the hypothalamic response to low leptin?
Release in NPY and AgRP in the arcuate nucleus, and MCH and orexin in the lateral hypothalamic area
What are the three phases of short term feeding regulation?
Cephalic, gastric, and intestinal (substrate)
What is the cephalic phase of short term feeding regulation?
Activation of SANS and PANS to prepare you for food; salivating, smelling, etc.
What is the gastric phase of short term feeding regulation?
When your stomach fills with food
What is the substrate phase of short term feeding regulation?
When your stomach is filled and the nutrients begin to get absorbed
What is ghrelin?
A peptide that stimulates hunger when stomach is empty; activates NPY and AgRP cells of the arcuate nucleus
What are three main satiety signals?
Gastric distension, CCK, and insulin
What is gastric distension?
Stomach stretching, which sends feedback to brain via vagus nerve
Where do the sensory axons of the vagus nerve enter the medulla?
Through the nucleus of the solitary tract
What is CCK?
Peptide that inhibits meal frequency and size: present in some intestinal lining cells; released by fatty food ingestion especially; acts on vagal sensory axons synergistically with gastric distension
What is required for glucose transport into cells?
Insulin
Why is insulin required for both anabolism and catabolism?
Need it to transport glucose into the liver/skeletal muscle/adipocytes for storage, but also to be liberated from storage to be used as fuel
How do levels of serotonin vary by food intake?
Low serotonin in the postabsorptive state; rising serotonin when anticipating food; spike during a meal, especially for carbs
What senses hypertonicity of blood and stimulates thirst?
OVLT (vascular organ of the lamina terminalis) in the telencephalon, lacks the BBB
What part of the hypothalamus detects cold/heat?
Anterior hypothalamus: causes TSH release/inhibition from anterior pituitary
