hypothalamus Flashcards
(32 cards)
the hypothalamus is involved in
functions that require the integration of somatic, autonomic, and endocrine mechanisms with motivated behavior expression
- feeding
- fight
- flight
- reproduction
the hypothalamus is anatomically linked to (projects and receives)
- reticular formation
- limbic system - emotion, memory
- pituitary gland - master gland of endocrine system
anatomical boundaries of hypothalamus
caudal: mammillary body
dorsal: hypothalamic sulcus
rostral: lamina terminalis
inferior: optic chiasm, pituitary stalk
lateral: internal capsule
divisions of the hypothalamus
- supraoptic/anterior - above optic chiasm
- tuberal/middle - above stalk of pituitary
- mammillary/posterior - above mammillary bodies
hypothalamic efferents
- medial forebrain bundle (MFB)
- dorsal longitudinal fasciculus (DLF)
- hypothalamo-hypophyseal tract
medial forebrain bundle (MFB)
- not a typical tract
- has variety of cells, fibers, etc.
- go to hypothalamus
dorsal longitudinal fasciculus (DLF)
- goes from hypothalamus to dorsal nucleus of vagus
- controls parasympathetic part of NS
hypothalamo-hypophyseal tract
- unique neurons
- synthesize proteins/hormones that are released into blood vessels
- 2 nuclei (supraoptic and paraventricular)
tubero-infundibular tract
- from hypothalamus
- neurosecretory cells secrete hormones
- released into blood vessels
afferents to hypothalamus
- reticular formation via MFB
- limbic pathways (fornix and amygdalar pathways)
- monoaminergic pathways
functions of anterior hypothalamus
- thermoregulation
- water balance
- circadian rhythms
- maternal behavior
- sleep
thermoregulation by hypothalamus
- somatic NS (shivering)
- autonomic NS (sweating, vasomotion)
- behavior
- thermoreceptor neurons
mechanism of fever
- body temp increases
- set-point is raised to a higher temperature
- we shiver because the muscles shiver to increase heat of the body
infection
- macrophage consumes bacteria
- release interleukins (1 and 6) to hypothalamus
- hypothalamus uses phospholipids to create arachidonic acid
- arachidonic acid forms prostaglandin by COX (inflammation)
- aspirin and NSAIDs inhibit COX (inhibits inflammatory and pain)
water balance
in high heat you lose water so the responses:
- endocrine (ADH)
- behavior (water drinking)
circadian rhythms
- generated by suprachiasmatic nucleus (SCN)
- SCN receives collaterals from optic tract (retino-hypothalamic fibers)
- lesions of SCN disrupt 24-hour temperature, sleep, and endocrine cycles
where is the suprachiasmatic nucleus
- above the optic chiasm
functions of tuberal hypothalamus
- control plasm hormone levels
- feeding behavior
- sexual behavior
- aggressive behavior
feeding behavior
concept of feeding center (LH) and satiety center (VMH)
- lesions of LH induce anorexia
- lesions of VMH (ventromedial nucelus of hypothalamus) induce obesity
important nuclei of feeding behavior
- arcuate nucleus
- paraventricular nucleus
sensing metabolic state (hormones?)
- ghrelin-appetite promoting (GI tract)
- insulin (pancreas)
- leptin (adipose tissue)
feeding behavior is controlled by
- behavior
- autonomic NS (salivary secretion, gastric secretion)
- metabolic need
aggressive behavior includes
- attack behavior
- defense behavior
- flight behavior
attack behavior is evoked by
stimulation of lateral hypothalamus
