Appetite And Feeding, Water DLA Flashcards
What are the short term regulators of appetite?
Shorttermregulators
– Insulin
• Produced by the pancreas (β cells) in response to rising blood glucose
– Ghrelin
• Produced by the empty stomach, stretch inhibits production
• Stimulates hunger
– Satiety peptides
• Produced by stomach and intestines during digestion, reduce hunger
What are the. Regulators of long term appetite ?
leptin
• Producedbyadipocytes
• levels relate to total body fat
• Higher levels reduce appetite
Explain hypothalamic regulation of behavior
The hypothalamus regulates caloric intake by a pair of antagonistic controls. In the arcuate nucleus, mutually inhibitory anorexigenic neurons suppress feeding, whereas orexigenic neurons stimulate appetite and feeding.
Hormonal feedback mechanisms influence feeding in both short and longer terms. Blood glucose levels are important acute determinants of feeding. Peptide hormones, which are about 20 amino acids long, are critical for short and long-term regulation of feeding. Leptin, a peptide produced in adipose tissue, influences feeding over time. Adipocytes (fat cells) release leptin into the bloodstream, and leptin levels correlate with total body fat levels, thus signaling long-term energy balance.
Adipocytes also respond to elevated insulin levels by increasing leptin production. Leptin then binds to specific receptors on neurons in the vagus nerve and the arcuate nucleus of the hypothalamus. An inhibitory neuronal link between the arcuate nucleus and the lateral hypothalamus in turn suppresses the consumption of food, reducing hunger after meals and potentially inducing weight loss if leptin levels remain elevated.
Ghrelin (“hunger hormone”) is the main opposing longer-term feedback hormone which increases appetite and drive to feed. It is produced by the stomach when empty, conversely stomach stretch inhibits ghrelin production. Ghrelin also acts on the vagus nerve and hypothalamus, directly opposing to effects of leptin.
Where are satiety peptides located?
Produced by small and large intestines after food intake
Where is Grelin made?
Hunger signal from stomach, reduced by stomach stretch
Where is leptin made?
Long term hunger regulator from adipose tissue
What is Ventromedial hypothalamic Syndrome?
Ventromedial Hypothalamic Syndrome (Fröhlich syndrome)
Fröhlich syndrome is a disorder of caloric balance characterized by obesity (besides other symptoms). The obesity results from damage to the ventromedial nucleus of the hypothalamus.
Explain hypothalamic regulation of balance
The hypothalamic regulation of water balance involves complicated inputs and outputs.
The hypothalamus osmoreceptors inputs from two circumventricular organs (VOLT and SFO), as well as from visceral afferents of the vagus nerve (i.e., blood pressure input through mechano-sensitive endings innervating the walls of major blood vessels and the heart). Magnocellular neurosecretory cells in the hypothalamus the release.
Angiotensin, a component of blood plasma, exerts its effects by circumventing the blood-brain barrier at the subfornical organ, one of the circumventricular organs.
After integration of the different input stimuli, the hypothalamus influences water conservation using ADH, which increases water retention in kidney tubules and neuronal output signals to the motivational system, thereby controlling drinking.
What is diabetes insipidus?
Absence of ADH induces excessive thirst and drinking and the secretion of large volumes of urine, up to 10 liters per day. The deficiency in ADH can reflect lesions of the supraoptic and paraventricular nuclei of the hypothalamus or interruption of the supraopticohypophyseal tract, the connection between the hypothalamus to the posterior pituitary. The condition is often treatable with ADH agonists
Describe anterior hypothalamic control of body temperature
Anterior hypothalamus- Temperature decrease
Integration of:
Autonomic control:
• Dilation of skin arterioles
• Sweating
Motivated behavior:
• Seeking cooler environment
• Remove clothing
Describe the posterior hypothalamic control of body temperature
Posterior hypothalamus - Temperature increase
Integration of:
Autonomic control:
• Constriction of skin arterioles
Motivated behavior:
• Shivering
• Seeking warmer environment
• Add clothing
How does the hypothalamus from the body temperature?
For the regulation of body temperature, the hypothalamus has two anatomically distinct antagonistic elements.
While the anterior hypothalamus decreases body temperature, the posterior hypothalamus increases body temperature.
Thermal feedback, arising from both temperature-sensitive hypothalamic cells and cutaneous thermoreceptors undergoes integration in the hypothalamus.
Changes in body temperature reflect hypothalamic output to the autonomic nervous system, which controls the constriction or dilation of blood vessels and activity of sweat glands. Somatic motor systems are also affected directly (e.g., to produce shivering) and indirectly (e.g., through actions on motivational systems (e.g., for seeking warmer or colder environments).
How is the hypothalamus stimulated in hypothermia?
Anterior hypothalamus —> temperature decrease
How is the hyperthalamus stimulated in hypothermia?
Posterior hypothalamus— temperature increase
Describe hyperthermia
Hyperthermia
Pathologically increased body temperature. It can reflect lesions of the anterior hypothalamus. Such lesions can leave the posterior hypothalamus unopposed, increasing metabolism and shivering (contributing to heat production) and peripheral vasoconstriction (reducing heat loss).
