The Homeostatic Brain Flashcards
tuber cinereum
grey swelling on ventral surface of the brain in region between mammillary bodies and optic chiasm
where is the hypophysial portal system?
median eminence
what are the 3 regions of they hypothalamus and how are they defined?
anterior/preoptic- anterior cerebral and anterior communicating arteries
tuberal- posterior communicating artery
posterior- posterior communicating, posteroir cerebral and basilar arteries
medial peroptic area
preoptic/anterior region
thermosensitive neurons for temperature regulation
gonadotropin secretion- reproductive and sexual behavior
suprachiasmatic nucleus
preoptic/anterior region
circadian rhythms
ventromedial nucleus
tuberal region
reproductive and sexual behaviors
glucose homeostasis and regulation of food intake
lateral hypothalamic area
tuberal region
feeding area- regulation of food intake
median forebrain bundle
limbic afferent to hypothalamus
hypothalamus to brainstem, amygdala, retina, and olfactory system. regulates somatic and metabolic activities associated w/ stress
fornix
limbic afferent to hypothalamus
connects hypothalamus to mammillary bodies
mammillary bodies to the anterior nuclei of the thalamus
stria terminalis
limbic afferent to hypothalamus
hypothalamus to amygdala
afferents to hypothalamus from brainstem
dorsal longitudinal fasciculus
median forebrain bundle
afferents to hypothalamus from retina
retinohypothalamic tract
major limbic hypothalamic efferents
mammillothalamic tract
median forebrain bundle
major reticular system hypothalamic efferents
mammillothalamic tract
major autonomic hypothalamic efferents
median forebrain bundle
dorsal longitudinal fasciculus
supraopticohypophyseal tract
carries axons from supraoptic and paraventricular nuclei to the posterior pituitary (neurohypophysis)
carry NTs AVP and oxytocin
oxytocin
released in response to sexual stimulation, uterine dilation, nursing, and stress
during late pregnancy, produces uterine contraction and milk secretion
implicated w/ increasing trust, empahty, eye contact etc.
lack of oxytocin may be associated w/ autism
pair bonding
oxytocin and AVP send neuronal contractions centrally and are important of affiliative states- maternal instincts, pair bonding, aggression, love
tuberoinfundibular tract
parvocellular neurons in periventricular regions of hypothalamus influence hormonal release from anterior pituitary
where do sex hormones feedback?
negative on GnRH in hypo
negative on anterior pituitary for FSH and LH
neuronal control of HPG axis
cells within preoptic area that synthesize and release peptide GnRH
show bursting behavior- critical for appropriate release of gonaotropic hormones
dont express sex hormone receptors- presynaptic neurons do
kisspeptin
presynaptic neurons that synthesize kisspeptin and act on G coupled proteins that regulate GnRH neurons
also play role in energy homeostasis and body fat.
regulated by circadian rhythms
act as sensors of the environment to make sure reproduction only occurs when conditions are right
importance of sex hormones in the brain in development
lots of receptors in POA
act in development to impoart permanent in neural structures that underlie man of the sexual differentiated aspects of the brain
sexually differentiated brain areas in rodents
VMN and POA
steroid hormones regulate VMN and POA circuits in these 2 ways
activational effects of gonadal steroids in the brain- activational effects of gonadal steroid are required for cyclicity in females, sex specific behaviors
organizational effects- act during a critical period to impart specific differences- POA is most well studies
master circadian regulator
suprachiasmatic nucleus
creates a cycle length of 24 hours- intrinsic, but also effected by environmental cues such as light- receive input from retina
effects eating, sleeping, energy, and temp via connections fo PVN, VMN, LHA
how is the circadian rhythm generated?
individual neurons in the SCN have transcription factors (CLOCK BMAL1, Cry, and Per) that regulate each other on a 24 cycle
what brain areas are important for feeding
ventromedial nucleus and arcuate (satiety) and lateral hypothalamic area (feeding)
casein kinases
regulate stability of circadian rhythm transcription factors
mutations cause shorter circadian rhythms
FASPS
orexigenic v anorexigenic
stimulates feeding vs suppresses feeding
ghrelin
acute signal that initiates food intake, decrease energy utilization and increase adiposity
acts on same neurons as leptin
produced in stomach when stomach is empty
CCK
acute info about gastro fil via vagal afferents to solitary nucleus and to limit meal size
leptin
provides peripheral signal from body to brain that reflects state of nutrition
produced by white adipose cells
designed to maintain adequate fat stores during lean times
along with insulin, has access to hypothalamus b/c of compromised BBB near areas postrema
leptin receptors
large numbers in hypothalamus
encoded by db gene, coming in short and long form- long form is important
members of cytokine superfamily- use JAK kinase
effects of leptin binding
occurs w/ high fat
inhibit production of AgRP, NPY and stimulate POMC (a-MSH) in arcuate nucleus
AgRP and NPY are orexigenic, a-MSH is anorexigenic
which nuclei house anorexigenic neurons and which nuclei house orexigenic neurons
anor- paraventricular PVN
ore- perifornical area PFA, Lateral hypothalamic area LHA
estrogen receptor related alpha
expressed in LHA and other areas linked to feeding
upregulated w/ caloric restriction
ESRAA null female mice are small and do not gain weight, show increased compulsive behaviors
orexin
expressed in LHA, helps regulate food intake and energy expenditure
inhibit by leptin and increased by ghrelin
orexinergic
narcolepsy- loss of orexin neurons
