Exam #3: Hypothalamus Flashcards

1
Q

What is the general function of the hypothalamus?

A

Hypothalamus= general function is “homeostasis” via

1) Neural mechanism
2) Humoral (pituitary gland)
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2
Q

Where is the hypothalamus? What are the boundaries?

A
  • Superior= hypothalamic sulcus i.e. the sulcus that separates the hypothalamus from the thalamus above
  • Inferior= optic chiasma, tuber cinereum, & mamillary bodies
  • Anterior= Lamina terminalis
  • Posterior= midbrain/ interpeduncular fossa

**Note that the tuber cinereum is a hollow eminence of gray matter (part of the hypothalamus) situated between the mammillary bodies and the optic chiasm

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3
Q

What structure separates the hypothalamus into medial and lateral portions?

A

Fornix

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4
Q

What is the major blood supply to the hypothalamus?

A

Perforating branches from the Circle of Willis

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5
Q

What are the functions of the hypothalamus?

A

Homeostasis including:

  • Sleep-wake cycle
  • Integration of emotional responses & behavior
  • ANS control center
  • Temp. regulation
  • Food intake
  • Water balance/ thirst
  • Endocrine system
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6
Q

What are the major inputs into the hypothalamus?

A

1) Limbic structures–emotions
2) Cerebral cortex–thoughts & decisions
3) Retina–light information
4) Brainstem & spinal cord–input from viscera
5) Intrinsic neurons i.e. osmoreceptors, chemoreceptors, & baroreceptors that monitor BP, osmolarity, glucose…etc.

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7
Q

How does the cerebral cortex effect they hypothalamus?

A
  • You can’t “will” your heart rate to increase

- However, thinking about exciting things e.g. naked woman can increase HR

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8
Q

What are the major outputs of the hypothalamus?

A

1) Pituitary gland= hormones & hormone releasing factors
2) Brainstem & spinal cord= influences on the viscera

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9
Q

How are most of the nuclei of the hypothalamus named? What are the two exceptions to the general rule that the hypothalamic nuclei are named relative to their position?

A

Position in the hypothalamus

*****Note: arcuate & mammillary bodies are naked off of their shape, not position

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10
Q

What is the general function of the suprachiasmatic nucleus?

A

Circadian rhythm i.e. the suprachiasmatic nucleus is the “master clock” of the body

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11
Q

What is the general function of the mammillary bodies?

A

Processing emotional information

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12
Q

What is the general function of the anterior & posterior nuclei of the hypothalamus? What is the difference?

A

Regulation of body temperature

  • Anterior= heat loss
  • Posterior= heat conservation/ production

*****Remember, posterior= preservation

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13
Q

What are the general functions of the ventromedial & lateral nuclei of the hypothalamus? What is the difference between the two

A

Both the lateral & ventromedial nuclei control satiety and feeding

  • Lateral= feeding or hunger center
  • Ventromedial= satiety center
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14
Q

What is the general function of the supraoptic & paraventricular nuclei of the hypothalamus?

A

These two nuclei are associated with the posterior hypothesis/ “neurohypophysis”
- Synthesize & release hormones of the posterior pituitary

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15
Q

What is the general function of the preoptic, medial preoptic, arcuate, & paraventricular nuclei of the hypothalamus?

A

These four nuclei are associated with the anterior pituitary

- Produce & release factors that stimulate or inhibit the anterior pituitary

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16
Q

What does a lesion to the hypothalamus usually result in?

A

“Hypothalamic Syndrome”

- Manifestation damage to many hypothalamic nuclei

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17
Q

What tract sends light information to the suprachiasmatic nucleus?

A

Retinosuprachiasmatic tract i.e. from the retina

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18
Q

What type of receptors are in the suprachiasmatic nucleus?

A

Malatonin

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19
Q

What is the function of melatonin?

A

Synchronization of the “master clock” in the hypothalamus

20
Q

What structure secretes melatonin?

A

Pineal gland

21
Q

What is the output of the suprachiastmatic nucleus?

A

Reticular formation in the brainstem

**Note that the reticularformation feedback to the suprachiasmatic nucleus via the dorsal longitudinal fasciculus

22
Q

What is the result of a tumor in the pineal gland?

A

Delayed or precocious onset of puberty

23
Q

What are the primary inputs to the mammillary bodies? What is the function of the mammillary bodies?

A

Hippocampus & amygdala–processing of emotional information

**Note that hippocampal input is via the fornix

24
Q

What are the two major output pathways from the mamillary bodies?

A
  • Mammillothalamic

- Mammillotegmental

25
Q

How do the mamillary bodies trigger appropriate visceral responses?

A

Output on brainstem PNS nuclei: VII, IX, X & SNS

26
Q

What are the fibers that connect the hippocampus to the hypothalamus (mamillary bodies)? What tract connects the amygdala to the hypothalamus?

A

Fornix & stria terminalis, respectively

27
Q

What is the shape of the fornix? How is this reflected on coronal section?

A

C-shaped; will see two parts of the fornix on cross-section

28
Q

Why is memory important to hypothalamic function?

A
  • Locating food & water

- Locations to avoid predators & tactics to increase survival

29
Q

What are the inputs to the ANS control of the hypothalamus?

A
  • Ascending visceral information from internal organs

- Limbic system with information about the emotional state of the organism

30
Q

What hypothalamic nuclei are associated with the PNS?

A

Preoptic & anterior nuclei

Function= pupillary constriction, salivation, decreased HR & BP, & increased peristalsis

31
Q

What hypothalamic nuclei are associated with the SNS?

A

Posterior & lateral nuclei

Function= pupillary dilation, decreased salivation, increased HR & BP, decreased peristalsis, and vasoconstriction

32
Q

What nuclei initiate heat loss? How?

A

Preoptic
Anterior

**I.e. the PNS nuclei that lead to sweating, vasodilation, and decreased motor activity

33
Q

What hypothalamic nuclei activate heat production? How?

A

Posterior

*****I.e. one of the SNS nuclei that functions in vasoconstriction, increased muscular activity, and TH

34
Q

What is the lateral nucleus of the hypothalamus associated with?

A

Eating– this is a potential “feeding center”

35
Q

What is the ventromedial nucleus of the hypothalamus associated with?

A

Potential satiety center

36
Q

Where are the osmoreceptors located that monitor the concentration/ hydration of the blood?

A

Lateral zone of the hypothalamus

37
Q

What nuclei are associated with control of the posterior pituitary? What tract are these nuclei associated with?

A

Supraoptic & paraventricular nuclei that are associated with the hypothalamohypophyseal tract

38
Q

What are the two hormones associated with the posterior pituitary?

A

ADH

Oxytocin

39
Q

What is the function of ADH?

A

Water conservation & increase blood pressure

40
Q

What are the functions of Oxytocin?

A

Uterine contraction

Milk letdown

41
Q

What are the two major nuclei that control the anterior pituitary?

A

Arcuate

Periventricular

42
Q

What are the releasing factors associated with the anterior pituitary gland?

A

SRH
CRH
GnRH
TRH

43
Q

What are the inhibitory factors associated with the anterior pituitary gland?

A

Somatostatin

PIF

44
Q

What connects the hypothalamus to the anterior pituitary gland?

A

Tuberohypophysial tract

45
Q

What does the medial forebrain bundle connect?

A

Lateral hypothalamus with septal nuceli & brainstem/ reticular formation

46
Q

How does consciousness alter the hypothalamus?

A

Conscious thoughts influence the hypothalamus

47
Q

What tract is going to be responsible for the “conscious” alteration of the hypothalamus?

A

Cortex–>hypothalamus called the “corticohypothalamic pathway”