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Flashcards in hypothalmus Deck (29)
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1
Q

function of hypothalamus

A
  • Homeostasis
  • maintenance of the body’s internal environment within normal physiological parameters
  • carries out the function through interconnections with areas of the brain related to emtions, Sleep/awakenings, hormones and autonomic activity
  • MONITORS blood glucose levels, blood osmolarity, body temperature and various hormone levels
2
Q

blood supply to hypothalamus

A
  • Perforating branches of circle of willis
3
Q

Boundaries of hypothalamus

A
  • Superior = hypothalamic sulcus
  • anterior = lamina terminalis
  • posterior = midbrain (interpeduncular fossa)
  • inferior = optic chiasma, tuber cinereum, mammillary bodies
4
Q

overview of hypothalamus

A
  • hypothalamus is nodal point of interconnecting structures relating to autonomic, endocrine, emotional and somatic functions
  • ALL FUNCTIONS relate to MAINTAINING homeostasis

–> stable internal environment, including temperature, hydration, glucose and monitoring hormone levels

5
Q

describe the major INPUTS

A
  • cerebrum = thoughts and decision
  • Limbic system = organizes appropriate behavioral responses associated with basic drives, “feeling”, motivation
  • Retina = light information (amount/duration of day/night)
  • Branstem and spinal cord = info from viscera
  • Intrinsic neurons = monitoring blood temp, osmolarity, hormone levels, glucose concentration
6
Q

describe major outputs

A
  • To brainstem and spinal cord = influences viscera, especially AUTONOMIC FUNCTION

–> VII, IX, X, T1-L2, S2-4

  • To PITUITARY = produces secretions (hormones and releasing factors)
7
Q

Suprachiasmatic nucleus

A
  • RECEIVES: light information from retina via RETINOHYPOTHALAMIC TRACT (retinosuprachiasmatic)
  • NUCLEUS contains MELATONIN RECEPTORS
  • Pineal secretes melatonin varying with light levels
  • melatonin helps SET and SYNCHRONIZE the “clock”
  • NUCLEUS CORRDINATES SLEEP/WAKEFULNESS CYCLES in the RETICULAR FOMRATION and other CIRCADIAN RHYTHMS
8
Q

Mammillary bodies (nuclei)

A
  • PROCESSES EMOTIONAL INFORMATION
  • INPUT: from hippocampus and amygdala (largest INPUT pathway is FORNIX)
  • OUTPUT: mammillothalamic, mammillotegmental tracts
  • HYPOTHALAMUS TRIGGERS APPROPRIATE VISCERAL RESPONSES:

–> brainstem parasympathetic nuclei (VII, IX, X)

–> spinal cord sympathetic and parasympathetic segments (T1-L2, S2-S4)

9
Q

Why is memory so important to hypothalamic function

A

REMEMBERING AND LEARNING

  • location of food sources increases chances of feeding
  • location of water sources increases changes of maintaining hydration
  • location of and tactics for avoiding predators increases chances of long-term survival
  • location of warmer climate associated with changing daylight length triggers migration for survival
  • location and status of receptivity of potential mates increases chances for procreation
10
Q

describe the autonomic control and integration of hypothalamus

A
  • INPUT: Ascending visceral info from internal organs (pain, empty stomach, drysness in mouth, enviornmental factors) and limbic system (emotional info)
  • OUTPUT: Parasympathetic and sympathetic
  • Fibers from various nuclei converge on PARAVENTRICULAR NUCLEUS and then via dorsal longitudinal fasciculas and mammillotegmental tracts to brainstem and spinal cord
11
Q

describe Parasympathetic control and integration of hypothalamus

A
  • Nuclei = PREOPTIC and ANTERIOR
  • Response = pupillary constriction, increased salivation, decreased BP and HR, increased GI peristalsis
12
Q

describe sympathetic control and integration of hypothalamus

A
  • Nuclei = POSTERIOR and LATERAL
  • RESPONSE = pupillary dilation, decreased salivation, INCREASED HR and BP, decreased GI peristalsis, VASOCONSTRICTION
13
Q

Anterior hypothalamus function in thermostat

A
  • NUCLEI: Preoptic and anterior nuclei initiate HEAT LOSS
  • VISCERAL RESPONSE: Sweating and vasodilation
  • decreased motor activity
  • BEHAVIOR: seek cooler environment, fan yourself
  • ASPIRIN causes antipyretic (fever reducing) effect by acting DIRECTLY on HYPOTHALAMUS
14
Q

Posterior hypothalmus function in thermostat

A
  • NUCLEI: posterior nuclei activate heat production
  • VASOCONSTRICTION
  • increased muscular activity (including shivering)
  • TH increases metabolic heat production
  • BEHAVIOR: put on more clothes
15
Q

describe the hypothalmus function of regulating food intact

A
  • LATERAL NUCLEUS = Stimulation INDUCES eating, “feeding or hunger” center
  • VENTROMEDIAL NUCLEUS = stimulation INHIBITS eating, “satiety” center
16
Q

Osmoreceptors

A
  • Monitor the concentration/hydration of blood
  • Stimulation of the lateral hypothalamus (zona incerta) STIMULATES DRINKING
17
Q

Glucoreceptors

A
  • monitor glucose levels
  • Affects feeding and satiety centers
18
Q

describe hormonal control of Posterior pituitary

A
  • hypothalamus synthesizes and releases the hormones of posterior pituitary (neurohypophysis)
  • Nuclei: supraoptic and paraventricular
  • Pathway: hypothalamo(supraoptico)hypophyseal tract
  • Hormones:

–> ADH(antidiuretic hormone, vasopressin) = water conservation, increase blood pressure

–> oxytocin = uterus contractions, milk let down

  • Intrinsic osmoreceptors sense and TRIGGER ADH to CONSERVE water
19
Q

What is the result of damage to posterior pituitary

A
  • INTERRUPT SYNTHESIS OF ADH leading to copious URINE FORMATION and CONSTANT THIRST

–> called DIABETES INSIPIDUS (tasteless)

  • Blood and urine sugar levels are within normal limits
20
Q

describe the hormonal control of anterior pituitary

A
  • hypothalamus produces releasing factors that STIMULATE or INHIBIT release of hormoens from anterior pituitary (adenohypophysis)
  • NUCLEI = ARCUATE, medial preoptic, preoptic, PERIVENTRICULAR nuclei
  • Pathway: tuberohypophysial (-infundibular) tract then vascular, hypothalmo-hypphyseal portal system to adenohypophysis (anterior pituitary)
  • Hormones: affect BODY GROWTH, thyroid secretion, gonadal function, adrenocortical secretion and mammary gland secretion
21
Q

describe visceral response to CONSCIOUS THOUGHT

A
  • thoughts, feelings, emotions can elicit:
  • SYMPATHETIC RESPONSE = sweating and blanching, accelerated HR, constipation, increased or decreased frequency of urination when WORRIED OR SCARRED
  • PARASYMPATHETIC RESPONSE = sexual dysfunction when depressed
  • INTERRUPTION of NORMAL CYCLING OF gonadotrophic hormones = skipped or delayed menstration with worry or depression
22
Q

describe Somatic response to CONSCIOUS and unconscious thoughts

A
  • Slouching and moving slowly when depressed (Limbic)
  • quick, agitated movements when STRESSED or ANXIOUS
  • thoughts and emotions DRIVE facial movements appropriate to those thoughts and emotions

–> sad face, happy face, frightened face

23
Q

describe the clinical correlation of direct connections between frontal lobs and hypothalmus

A
  • Stroke victums can still move otherwise paralyzed muscles with EMOTIONAL RESPONSE

–> ex: smiling at a joke (duchenne smile)

  • The muscles are ONLY PARALYZED for VOLUNTARY MOVEMENT (pyramid pathway, corticonuclear, is interrupted)
  • pathway from cerebrum to hypothalamus takes DIFFERENT ROUTE (not well defined
24
Q

function of suprachiasmatic

A
  • circadian cycles, the clock
25
Q

mammillary function

A
  • processing emotional info
26
Q

anterior and posterior nucleus

A
  • regulate body temp
27
Q

Ventromedial, lateral

A

satiety and feeding

28
Q

supraoptic, paraventricular

A
  • produce hormones in posterior pituitary
29
Q

preoptic, medial preoptic, arcuate, periventricular

A
  • release or inhibit hormones in anterior pituitary