integrative systems Flashcards
draw a rough diagram of the hypothalmic nuclei
:)
what are the functional subdivisions of the hypothalamus?
LATERAL ZONE
– regulation of feeding
– regulation of sleep-awakeness
– integrates info from other hypothalmic nuclei and telencephalic structures engaged in emotions
MIDDLE ZONE
– regulates release of oxytocin and vasopressin from posterior pituitary gland
– regulates ANS
– sets the biological rhythm via its nuclei
– magnocellular secretory system
PARAVENTRICULAR ZONE
– regulates hormone release from anterior pituitary
– parvocellular secretory system
describe the blood supply to the hypothalamus
hypothalamic branches off posterior communicating artery supply the hypothalamus
BBB is altered and leaky around hypothalamus as it must detect changes in blood
why does the internal carotid artery run through the venous cavernous sinus?
all cranial nerves sit in dura mater to define boundary of cavernous part. abducens nerve located WITHIN cavernous part close to the carotid artery. if internal carotid ruptures, abducens nerve damaged
how des the hypophysis develop?
neurohypophysis develops on floor of diencephalon
adenohypophysis develops on roof of mouth
how can you use histology to differentiate between the neurohypophysis and adenohypophysis?
adenohypophysis (ant. pituitary) rich in blood vessles
neurohypophysis only contains nerve terminals, no cell bodies
which hormones are secreted from the adenohypophysis?
1) growth hormone, GH
2) thyroid stimulating hormone, TSH
3) folicle stimulating hormone, FSH
4) prolactin, PRL
5) adenocorticotrophic hormone, ACTH
6) luteinising hormone, LH
7) melanocyte stimulating hormone, MSH
axon terminals in the neurohypophysis are extensions of which nuclei?
paraventricular nuclei → oxytocin
supraoptic nuclei → vasopressin (ADH)
TRUE OF FALSE:
the neurohypophysis synthesises and releases hormones
FALSE
the neurohypophysis stores and releases hormones
oxytocin and vasopressin (ADH) are synthesised by hypothalamic neurons
function the paraventricular nuclei
located within the hypothalamus
contains magnocellular neurosecretory neurons
regulate hormone release from adrenohypophysis (ant. pituitary)
how does the hypothalamus control emotions, learning, and reproductive behaviour?
hypothalamus has bidirectional pathways to limbic structures to control learning, emotions and reproductive behaviour
hypothalamus projects to amygdala via fornix or stria terminalis
hypothalamus connects to septal areas via medial forebrain bundle
what is the function of circadian rhythm? what are the components?
circadian clock restricts particular processes to the appropriate time - active phase or inactive phase in a 24 hour cycle
physiological processes occur in response to time cues
components:
• amplitude
• period
• zeitgeber → stimulus that functions as a time cue
• circadian rhythm → rhythm which oscillated with a period of 24 hours in absence of zeitgebers
which genes and proteins are particularly important in the cellular clock?
CLOCK
BMAL1
PERIOD (PER)
CRYPTOCHROME (CRY)
how is each individual cellular clock kept synchronous?
the SCN (paired nuclei at base of hypothalamus) acts as a “master clock” to keep cellular clocks in synchrony
SCN receives input from retinohypothalmic tract → provides non-visual photic info
projects to many regions:
• ARC → regulates feeding centres
• LHA → secretes neuropeptides which regulate behaviour
• PVN → integrates signals and transmits to brainstem, relaying info to periphery
what is the result of a lesion to the SNC
completely arrhythmic sleep cycle
describe how physiological processes are regulated in response to light
retinal ganglion cells are stimulated by daylight (blue light)
RGCs activates SCN
SCN increases gene expression of particular proteins
causes regulation of certain physiological processes
during day: ↑ body temp ↑ cortisol hormone ↑ blood pressure ↓ melatonin ↓ GH ↓ testosterone ↓ prolactin
during night: ↓ body temp ↓ cortisol hormone ↓ blood pressure ↑ melatonin ↑ GH ↑ testosterone ↑ prolactin
how is communication re. the body clock controlled
paraventricular nucleus is the centre of communication
has limbic, hypothalamic, brain stem + peripheral connections
all are time-stamped
what happens if the internal body clock is altered?
change to internal clock damages efficiency of hormone release
e.g. blood glucose will remain high for long time —> leads to obesity
describe how information travels to regulate melatonin release
melatonin only released at night (time-cue)
1) retina detects light
2) signals to suprachiasmatic nuclei (SCN)
3) SCN sends rhythmic signals to paraventricular nuclei
4) interomediolateral column of spinal cord
5) superior cervical ganglion
6) pineal gland
7) pineal gland releases melatonin
8) neg. feedback causes disinhibition of suprachiasmatic nuclei
LIGHT PERIOD:
• PVN inhibited by GABAergic neurons
• no melatonin release
DARK PERIOD:
• GABAergic neurons silent
• enables excitatory glutamatergic input to stimule PVN
• melatonin release
how is learning and memory influenced by circadian clock?
absorb more information during day time
consolidation of memories regulated by internal clock
rats learn conditioning more efficiently at day compared to night
