Hypothalamus & Pituitary Gland Flashcards
what are the functions of the Hypothalamus?
The hypothalamus integrates functions that maintain chemical and temperature homeostasis. It functions with the limbic system and controls the release of hormones from the anterior and posterior pituitary. It synthesizes and releases hypophysiotropic hormones in the cell bodies of neurons located in the hypothalamus:
what are the two mechanisms exerted by the hypothalamus?
Neural (local circuits, afferent and efferent projections)
Neurohumoral (i.e., hormonal, vascular, neuroendocrine functions, neuroimmune influences)
what are the three sites of functional influence?
anterior pituitary
posterior pituitary
non pituitary
what are anterior pituitary influences?
Stress “Fight (aggressive behavior) or Flight (fear)” Sexual behavior and reproduction Growth Metabolism
what are the posterior pituitary influences?
Body fluid balance
Maternal behavior
what are the non-pituitary influences?
Temperature regulation Immune system regulation Circadian rhythm influences on hormonal fluctuations, sleep, etc. Appetite regulation Autonomic Nervous System
what are the afferent connections to the hypothalamus? functions?
the fornix - communicates from the hippocampus
medial forebrain - from the olfactory areas
stria terminalis - from the amygdala
peduncle - from the visceral afferent fibers
what are the efferent connections to the hypothalamus? functions?
dorsal longitudinal fasciculus - to parasympathetic nuclei
mamillotegmental tract - fibers to the tegmentum of the midbrain
mamillothalamic fasciculus to cingulate gyrus
Hypothalamic - hypophyseal tract communicates with pituitary gland
so we know that the mamillotegmental tract is part of the efferent connections to the hypothalamus, what is this pathway?
tegmentum of the midbrain - reticular formation - hypothalamus, cranial nerve nuclei, spinal cord
what is the pituitary gland divided into?
adenohypophysis and neurohypophysis
what is the adenohypophysis?
anterior pituitary containing the Pars tuberalis, Pars intermedia, Pars distalis
what is the neurohypophysis?
posterior pituitary containing infundibular stalk
where does the anterior and posterior pituitary glands sit?
the hypophyseal fossa in the sella turcica of the sphenoid bone
what supplies the anterior portion of the pituitary gland? posterior portion of the pituitary gland?
superior hypophyseal artery; inferior hypophyseal artery
this structure is characterized by sexual dimorphism involving hormonal influences on neuronal maturation? what hormone does this structure contain?
medial preoptic nucleus; gonadotropin-releasing hormone
this structure maintains constant body temperatures?
anterior preoptic region
this structure receives direct retinal input? its also responsible for this rhythm?
suprachiasmatic nucleus; circadian rhythm
these are cells whose axons project to the posterior pituitary?
Neurosecretory cells
this nucleus secretes oxytocin?
Paraventricular nucleus
this nucleus secretes vasopressin and corticotropin releasing hormone?
Supraoptic nucleus
these neurons project to parasympathetic nuclei of the brainstem and spinal cord?
Paraventricular region neurons
what is oxytocin?
a hormone that starts smooth muscle contraction in the uterus and allows for milk let down not production of, its what releases the milk
what controls the systemic feedback to the hypothalamus?
CircumVentricular Organs (OVLT and SFO) which monitor osmolarity of the body, 290 osmolarity is the threshold
Organum vasculosum laminae terminalis
subfornical organ
these neurons are involved in feeding, reproductive, and parenting behavior, thermoregulation?
Dorsomedial and Ventromedial Nuclei
these nuclei (name the two) regulate appetite and food intake? what is the affect of a lesion on the medial and lateral part?
anterior nuclei comprised of a medial and lateral part
lesions on medial part cause obesity
lesions on the lateral part cause anorexia
these region is responsible for temperature regulation, temperature changes like sweating, arousal and shift of attention. What happens if there is a lesion here?
posterior hypothalamic region; lesion causes hypothermia
this structure is involved in limbic forebrain and midbrain functional integration?
mammillary body
what is the effect on the hypothalamus if there are lesions in associated cortical regions?
emotion pain drives (sex, hunger, thirst) fight or flight forms of anxiety
T/F, circumventricular organs are located around the hypothalamus?
T, these organs mediate peripheral hormone release and “afferent” humoral feedback
i.e.- neurohypophysis secretes vasopressin, oxytocin from the pituitary
T/F, Subfornical organ and Organum Vaculosum Lamina
Terminalis are associated with chemoreception of osmolarity?
T
this Circumventricular organs is responsible in regulation of circadian rhythms via melatonin release
pineal gland
this Circumventricular organs is responsible in glycoprotein secretion into CSF; functions unknown?
subcommissural organ
this Circumventricular organs is responsible in regulation of the anterior pituitary gland?
median eminence
this Circumventricular organs is chemosensitive, emetic?
area postrema
what are the three Systemic Regulatory Feedback to Hypothalamus?
Via breaches in the blood-brain barrier
Via peripheral pressure (baro-) receptors and central pathways (e.g., hypovolemia (decrease in blood volume)
Via lipid-soluble gonadal and adrenal steroids
in terms of appetite, what is the anterior nuclei?
regulate appetite and food intake. Medial part lesion causes obesity, lateral part lesion causes anorexia
