Neuro - Anat & Phys (Hypothalamus, Sleep, & Posterior Pituitary) Flashcards
Pg. 450-451 in First Aid 2014 Pg. 414-415 in First Aid 2013 Sections include: -Hypothalamus -Sleep Physiology -Posterior Pituitary (Neurohypophysis)
What are the functions of the hypothalamus?
The hypothalamus wears TAN HATS - Thirst and water balance, Adenohypophysis control (regulates anterior pituitary), Neurohypophysis releases hormones produced in the hypothalamus, Hunger, Autonomic regulation, Temperature regulation, Sexual urges.
Which are the inputs into the hypothalamus through areas not protected by the blood-brain barrier? What is the function/relevance of each of these inputs?
Inputs (areas not protected by blood-brain barrier): (1) OVLT (organum vasculosum of the lamina terminalis; senses change in osmolarity), (2) Area postrema (responds to emetics)
What makes ADH?
Supraoptic nucleus (of hypothalamus) makes ADH
What makes oxytoxin?
Paraventricular nucleus (of hypothalamus) makes oxytocin
What do ADH & oxytoxin have in common?
ADH and oxytocin: made by hypothalamus but stored & released by posterior pituitary
What part of the brain is associated with hunger?
Lateral area of hypothalamus
What function is associated with the lateral area of hypothalamus? What happens if you destruct this area?
Hunger; Destruction –> anorexia, failure to thrive (infants); Think: “If you zap your LATERAL nucleus, you shrink LATERLly”
What part of the brain is associated with satiety?
Ventromedial area of hypothalamus
What function is associated with the ventromedial area of hypothalamus? What happens if you destruct this area? Give an example of such destruction.
Satiety. Destruction (e.g., craniopharyngioma) –> hyperphagia; Think: “If you zap your VENTROMEDIAL nucleus, you grow VENTRALly and MEDIALly.”
What parts and functions of the brain does leptin affect, and how?
Lateral area (Hunger) - Inhibited by leptin; Ventromedial area (Satiety) - Stimulated by leptin
What function(s) is/are associated with the Anterior hypothalamus?
Cooling, Parasympathetic; Think: “Anterior nucleus = cool off (cooling, pArasympathetic). A/C = anterior cooling.”
What function(s) is/are associated with the Posterior hypothalamus?
Heating, sympathetic; Think: “Posterior nucleus = get fired up (heating, sympathetic). If you zap your Posterior hypothalamus, you become a Poikilotherm (cold-blooded, like a snake)”
What part of the brain is associated with circadian rhythm?
Suprachiasmatic nucleus of hypothalamus; Think: “you need SLEEP to be CHARISMATIC (chiasmatic).”
What regulates the sleep cycle? What drives this regulator?
Sleep cycle is regulated by the circadian rhythm, which is driven by SCN (suprachiasmatic nucleus) of hypothalamus
What are the 4 substances that Circardian rhythm releases, and under what conditions?
Circadian rhythm controls nocturnal release of ACTH, prolactin, melatonin, and norepinephrine
What regulates SCN? What events connect SCN with melatonin?
SCN is regulated by environment (e.g., light); Suprachiasmatic nucleus (SCN) –> norepinephrine release –> pineal gland –> melatonin
What are the two stages of sleep physiology?
Two stages: rapid-eye movement (REM) and non-REM.
What causes extraocular movements during REM sleep?
Extraocular movements during REM sleep due to activity of PPRF (paramedian pontine reticular formation/conjugate gaze center).
How often does REM sleep occur? How does it progress through the night?
REM sleep occurs every 90 minutes, and duration increase through the night.
What are 3 drugs associated with decreased REM sleep and delta wave sleep?
(1) Alcohol, (2) Benzodiazepines, and (3) Barbiturates are associated with decreased REM sleep and delta wave sleep
What effect does norepinephrine have on REM sleep?
Norepinephrine also decrease REM sleep
What is the preferred drug for treat bedwetting? What substance does this drug mimic? What is another name for bedwetting? What is a less preferred drug for treating bedwetting, and why?
Treat bedwetting (sleep enuresis) with oral desmopressin acetate (DDAVP), which mimics ADH; Preferred over imipramine because of the latter’s adverse effects
For what 2 sleep-related conditions are Benzodiazepines useful?
Benzodiazepines are useful for night terrors and sleepwalking
Name the 4 major sleep stages.
(1) Awake (eyes open) (2) Awake (eyes closed) (3) Non-REM sleep (4) REM sleep
Describe the Awake sleep stage.
Alert, active mental concentration
What is the EEG waveform in Awake (eyes open) versus Awake (eyes closed) sleep stages?
Awake (eyes open): Beta (highest frequency, lowest amplitude); Awake (eyes closed): Alpha
Which EEG waveform has the highest frequency and lowest amplitude? With what sleep stage is it associated?
Beta (highest frequency, lowest amplitude); Awake (eyes open)
What are the stages of Non-REM sleep? What percentage of total sleep time do young adults spend in each?
(1) Stage N1 (5%) (2) Stage N2 (45%) (3) Stage N3 (25%)
Describe Stage N1 Non-REM sleep. What is its EEG waveform?
Light sleep; Theta
Describe Stage N2 Non-REM sleep. What is (are) its EEG waveform(s)?
Deeper sleep, when bruxism occurs; Sleep spindles and K complexes
During which sleep stage does Bruxism occur?
Stage N2 of Non-REM sleep
Describe Stage N3 Non-REM sleep. What is (are) its EEG waveform(s)?
Deepest non-REM sleep (slow-wave sleep); when sleepwalking, night terrors, and bedwetting occur; Delta (lowest frequency, highest amplitude)
In what sleep stage does sleepwalking occur? What are 2 other occurrences during this sleep stage?
Stage N3 Non-REM sleep; when sleepwalking, night terrors, and bedwetting occur
Which EEG waveform has the lowest frequency and highest amplitude? With what sleep stage is it associated?
Delta (lowest frequency, highest amplitude); Stage N3 Non-REM sleep
What percentage of total sleep time do young adults spend in REM sleep?
REM sleep (25%)
Describe REM sleep. What is (are) its EEG waveform(s)?
Loss of motor tone, increased brain O2 use, increased and variable pulse and blood pressure; when dreaming and penile/clitoral tumescence occur; may serve a memory processing function; Beta
In what sleep stage does dreaming occur? What other significant events occur in this sleeps stage?
REM sleep; When dreaming and penile/clitoral tumescence occur; May serve a memory processing function
Name the sleep stages and their EEG waveforms.
(1) Awake (eyes open) - Beta (highest frequency, lowest amplitude) (2) Awake (eyes closed) - Alpha (3) Non-REM Stage N1 - Theta (4) Non-REM Stage N2 - Sleep spindles and K complexes (5) Non-REM Stage N3 - Delta (lowest frequency, highest amplitude) (6) REM sleep - Beta; Think: “at night, BATS Drink Blood”
Draw the waves (relatively) of the sleep stages.
See p. 451 in First Aid 2014 for visual.
What axonal projections does the posterior pituitary receive?
Receives hypothalamic axonal projections from supraoptic (ADH) and paraventricular (oxytocin) nuclei
What makes ADH?
Supraoptic nucleus of hypothalamus
What makes oxytocin?
Paraventricular nucleus of hypothalamus
What are alternative names for the anterior and posterior pituitaries?
Anterior pituitary = Adenohypophysis; Posterior pituitary = Neurohypophysis
Use the roots of the word “oxytocin” to remember its function.
Oxytocin: oxys = quick; tocos = birth
