Week 7 Part 3 notes Flashcards
What does hypothalamus control via projections
activity in autonomic, endocrine, and somatic pathways
important projections of hypothalamus
- cd brainstem netowrks/ centers controlling autonomic fx
- periaqueductal Grey
- cd brainstem and spinal cord circuits involved in somatic motor contorl
- pituitary gland
hypothalamus -> cd brainstem netowrk. centers controlling autonomic fx
- control and coordinate autonomic response to maintain homeostasis
- hypothalamus also projects directly to preganglionic symp and parasympathetic neurons in brainstem and spinal cord permitting direct control of autonomic output
hypothalamus -> periaqueductal grey
integrating behavioral and autonomic response; involved in fight or flight, repro and micturition
hypothalamus -> cd brainstem and spinal cord circuits involved in somatic motor control
- initiate behaviors involving somatic musculature:
- breathing
- shivering
- sterotyped aggressive or exploratory motor patterns
- stereotyped reproductive posturing
- does this via facilitating brainstem motor circuits already organized to coordinate these behaviors
hypothalamus -> pituitary gland
- controls endocrine output form Adeno- and neurohypophysis
- output can affect virtually every tissue in body
anterior lobe of pitutitary
adenohypopphysis; made up of clusters of glandular epithelial cells surrounded by sinusoids
hypothalamus control of adenohypophysis
via hypothalamic- hypophyseal portale system
blood supplying adenohypophysis
passes through network of fenestrated capillaries in infundibulum b4 reaching sinusoids in adenohypophysis
axons from neurons in nuclei of hypothalamus -> terminate on cap beds in proximal pt infundibulum -> peptides released from these axons -> peptides carried via hypophyseal portal veins -> sinusoids in adenohypophysis
peptides -> adenophypophysis
act as releasing or inhibitory factor to control secretion of hormones from glandular cells in adenohypophysis; hormones absorbed via sinusoids -> systemic circulation -> distant tissues
neurohypophysis
posterior lobe of pituitary gland; consists of nerve fibers and terminals form neurons in certain nuclei of hypothalamus; cells in nuclei produce vasopressin and oxytocin; axon terminals release these hormones directly on fenestrated capillaries within neurohypophysis; hormones enter systemic circulation -> distant tissues (kidneys, mammary glands, vascular smooth muscle, and brain itself)
hypothalamus and adrenal medulla
hypothalamus has neutral control of adrenal medulla via ANS
- neurons in hypothalamus -> preganglionic neurons in spinal cord -> splanchnic nerves -> adrenal medulla -> control release epinephrine and norepinephrine (from adrenal medulla)
secretory cells of adrenal medulla
essential fx as post-ganglionic neurons which release neurotransmitter into circulation fo fx as hormone the circulating epinephrine and norepinephrine play key roles in stress response -> sympathetic stimulation
hypothalamus location
located ventrally within diencephalon surrounding v portion of 3rd ventricle; bounded rostrally by optic chiasm and lamina terminals; mammillary bodies at cd ventral aspect of hypothalamus
hypothalamus and midbrain tegmentum
continuous caudally
hypophysis location
attached to ventral aspect of hypothalamus by infundibulum
hypothalamus is within
middle cr fossa
hypothalamus and cavernous sinus
may be impacted by lesions in region of cavernous sinus
hypothalamus medial zone
closer to 3rd ventricle; organized into discrete nuclei with defined functions; contains nuclei that regulate anatomic respiratory and reproductive fx as well as thermoregulation and more complex behaviors; some nuclei contain neurons controlling secretion from adeno- and neurohypophysis (anterior and posterior pituitary gland)
hypothalamus lateral zone
sometimes considered continuation of brainstem reticular formation; includes diffusely scattered neurons and numerous axons including axons associated with ARAS and other neuromodulatory pathways
which zone of hypothalamus is associated with ARAS and other neuromodulatory pathways
hypothalamus lateral zone
damage fibers of hypothalamus lateral zone
damage to these fibers by lesions of hypothalamus can produce depression or coma
input to hypothalamus
- retina, olfactory, and vomeronasal systems
- cutaneous receptors
- monoaminergic pathways
- nucleus of solitary tract
- hippocampal formation
- other limbic strcutres
- circulating hormones
- osmoreceptors
- thermoreceptors
hypothalamus integrates
information from diverse range of inputs that include most sensory systems, neuromodulatory pathways, and higher levels of brain; info used to generate responses that ensure maintenance of homeostasis or facilitate reproductive and basic survival behaviors
