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Systems Neuroscience > Diencephalon- Hypothalamus (2/4) > Flashcards

Diencephalon- Hypothalamus (2/4) Flashcards

1
Q

Functions of the Hypothalamus

A
  • Endocrine (physiological coordination)
  • By the release from neurons in various hypothalamic nuclei of specific releasing hormones
  • Control thyroid, adrenal gland and gonads
  • Regulate GH and PRL secretion.
  • Regulate oxytocin (uterine contractions, lactation) and vasopressin (water balance) release from the posterior pituitary
  • Non-endocrine (homeostatic/external->internal coordination)
  • Regulate body temperature
  • Regulate food intake (though I take issue with this being considered “non-endocrine”)
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2
Q

what 3 main things is the hypothalamus concerned with?

***

A

Growth
Reproduction
Metabolism

The hypothalamus helps you maintain homeostasis while also letting you respond to acute situations

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3
Q

The systems under the control of the hypothalamus

A

autonomic, endocrine, limbic

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4
Q

How does hypothalamus work?

***

A

It integrates sensory, cognitive, and emotional information to regulate endocrine, autonomic, and behavioral responses

  • Receive information from afferents
  • Ascending sensory signals from brainstem and spinal cord
  • Descending information from the cortex and limbic system
  • Send information through efferents and through hormones
  • Connections to other brain structures
  • Efferents to autonomic nervous system
  • Direct and less direct connection to pituitary
  • Release of hormones
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5
Q

Examples of hypothalmus working

dont need

A

Examples:

  • Blood osmolality is off –>be thirsty and go find some water
  • Ovary made a mature egg-> probably should go find a way to fertilize it
    • Time to grow -> let’s talk to the bones and thyroid about making that happen… and maybe we should make you eat more too
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6
Q

Pituitary gland (in relation to hypothalamus)

**

A
  • Pituitary gland is connected to the hypothalamus by the axons of neurons coming down to terminate in the posterior pituitary
  • Anterior pituitary: not connected to hypothalamus; receives signals (mostly releasing hormones) from hypothalamus via the portal blood supply; releases hormones into general circulation. The actual “gland” part of the pituitary
  • Posterior pituitary: continuous with hypothalamus; releases hormones made from certain areas of the hypothalamus into the general circulation
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7
Q

Rostral caudal axis of nuclei in the hypothalamus

(divisions and subdivisions of hypothalamus)

*4 main divisions

A
  • Preoptic area: medial preoptic nucleus
  • Supraoptic/Anterior hypothalamus: suprachiasmatic nucleus (SCN); paraventricular nucleus (PVN); periventricular nucleus and supraoptic nuclei (SON)
  • Middle hypothalamus: arcuate nucleus; ventromedial nucleus and median eminence.
  • Posterior hypothalamus: arcuate nucleus, tuberomammillary nucleus, mammillary region
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8
Q

Supraoptic/Anterior hypothalamus: parts

-dont need to know

A

*Supraoptic/Anterior hypothalamus: anterior nucleus, suprachiasmatic nucleus (SCN); paraventricular nucleus (PVN); periventricular nucleus and supraoptic nuclei (SON)

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9
Q

PVN

-when:

A

-(of the Supraoptic/Anterior hypothalamus)

PVN: mostly oxytocin production to regulate lactation, childbirth, and perhaps social relations

  • Oxytocin suggested to be important for pair-bonding, parent-child bonding, and group-bonding
  • Oxytocin released during childbirth to induce and *maintain contractions
  • Oxytocin necessary for milk ejection during lactation

(paraventricular nucleus)

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10
Q

Anterior nucleus (of the Supraoptic/Anterior hypothalamus)

-dont need to know!

A

*Anterior nucleus: a lot of things, but very important for body temperature regulation

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11
Q

(SON)

A

(of the Supraoptic/Anterior hypothalamus)

supraoptic nuclei

SON: mostly vasopressin production to control water and electrolyte balance

  • Vasopressin controls water retention at the level of the kidney
  • Vasopressin can also kick in if you begin to hemorrhage in an effort to try to increase your blood volume

(part of the Supraoptic/Anterior hypothalamus)

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12
Q

Both the PVN and the SON do what?

A
  • Both send their axons down through the infundibular tract and release their products directly from the posterior pituitary
  • Both areas can participate in stress responses

(The PVN and the SON can work together: participating in things like stress response. Everyday job duties are independent of eachother but they can be coordinated)(bc they are neighbors)

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13
Q

Middle hypothalamus: subdivisons

-do not need to know

A

*arcuate nucleus, dorsomedial, ventromedial nucleus, and median eminence.

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14
Q

Arcuate nucleus

-do not need to know

A

: (a subdivision of middle hypothalamus)

*Arcuate nucleus: lots of stuff… dopamine to inhibit prolactin, other hormones to influence feeding

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15
Q

Dorsomedial nucleus

A

Dorsomedial: emotional behavior?
Stimulate –> sham rage
Dorsomedial nucleus- possible link for emotional eating???

  • part of the Food Intake Circuitry of the Hypothalamus
  • Arcuate nucleus –> LHA, ventromedial nucleus, paraventricular nucleus, and dorsomedial nucleus
  • No direct interconnections between the VMH and LHA, only those processed through the dorsomedial nucleus
  • Dorsomedial nucleus- possible link for emotional eating???

(a subdivision of middle hypothalamus)

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16
Q

Ventromedial nucleus

A

(a subdivision of middle hypothalamus)

-VMH

Ventromedial nucleus: satiety center

  • Stimulate –> cease eating
  • Lesion –> overeat and weight gain
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17
Q

Food Intake Circuitry- Hypothalamus

A
  • LHA- “feeding” center (when LHA is excited : triggers feeding behavior)
  • Lateral Hypothalamic Area
  • VMH- “satiety” center
  • Arcuate nucleus –> LHA, ventromedial nucleus, paraventricular nucleus, and dorsomedial nucleus
  • Paraventricular nucleus returns inputs to the arcuate nucleus
  • No direct interconnections between the VMH and LHA, only those processed through the dorsomedial nucleus
  • Dorsomedial nucleus- possible link for emotional eating???
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18
Q

Middle hypothalamus: subdivisions

dont need

A

arcuate nucleus, dorsomedial, ventromedial nucleus, and median eminence.

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19
Q

Median eminence:

A

Median eminence: where substances from the hypothalamus are released into the portal blood supply around the pituitary and can also help them get to general blood circulation

Schematic diagram of the median eminence showing the organization of its three major zones: ependymal zone (E), internal zone (ZI), and external zone (ZE). ZE is invigilated by portal capillaries which are contacted by axon terminals of the tuberoinfundibular system and by processes of specialized ependymal cells, the tanycytes.

(division of the Middle hypothalamus)

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20
Q

Posterior hypothalamus: subdivisons

-dont need to know

A

arcuate nucleus, tuberomammillary nucleus, mammillary region

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21
Q

Mammillary region and mammillary bodies

A

*Mammillary region and mammillary bodies: important for limbic and memory function

Important tracts: mammillothalamic tract and fornix

(Posterior hypothalamus subdivison)

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22
Q

Mammillothalamic Tract

A
  • Part of the Papez circuit
  • Connects mammillary nuclei (of the hypothalamus) to anterior thalamus
  • Important for episodic memory and emotional expression

-The mammillothalamic tract provides a bi-directional pathway connecting the mammillary bodies with the anterior thalamic nucleus.

23
Q

Fornix

  • originiates:
  • **
A
  • Major output of the hippocampus
  • Terminates in the mammillary bodies : Information ultimately gets sent to anterior thalamus via the mammillothalamic tract
  • Part of the limbic system and Papez circuit
  • Probably involved in emotional experience or expression
  • Really important for episodic memory formation (!)
  • Damage –> inability to form new declarative or episodic memories

[septum to hippocampai]

-The fornix is both afferent and efferent with respect to the mammillary bodies providing a bi-directional connection with the subiculum of the hippocampal formation.

24
Q

Stria Terminalis

***

A

Brings information from the amygdala to the hypothalamus and terminates in the septal nuclei, preoptic area, and medial hypothalamic zone

  • helping to respond to the scary thing
  • I do NOT think it is bidirectional: wait bruh… maybe it is
25
Q

So, what is the deal with the hypothalamus and emotional expression?

-dont think you need to know

A
  • The hypothalamus initiates a lot of your behavioral responses to your environment : Danger- fight or flee, Changes in heart rate, respiration, digestion…, All of these are behavioral components of your emotional response
  • Also, controls things like reproduction and social interactions which overlap onto emotion: Love, lust, etc; Parent-child bonding

{emotions are a survival thing: reason why like thing or don’t like thing (things make you angry or happy). Comes down to things that are for functioning (optimally) }

26
Q

Hypothalamus and Stress Response

-dont think you need to know

A

Autonomic Nervous System –> Epinenphrine/Norepinephrine

{Autonomic Nervous System –> (fight or flight) –> neurohypothalamus}

Adrenal Glands –> Cortisol

  • Ultimate results: Fight or Flight, big changes under long term stress
  • Can include: increased heart rate, suppressed digestion, energy mobilization, suppression of immune system and inflammation, suppression of reproductive systems
27
Q

Hypothalamus and Stress Response

-dont think you need to know

A
  • Autonomic Nervous System –> Epinenphrine/Norepinephrine
  • Adrenal Glands –> Cortisol
  • Ultimate results: Fight or Flight, big changes under long term stress
  • Can include: increased heart rate, suppressed digestion, energy mobilization, suppression of immune system and inflammation, suppression of reproductive systems
28
Q

Why are we spending an entire lecture on the hypothalamus when we breezed over the cortex?

A

Answer: The hypothalamus is much more important for your survival
“Destruction of the hypothalamus is not compatible with life” (Williams Textbook of Endocrinology)
“it is perhaps the most important structure in the entire body.” (Fundamental Neuroscience for Basic and Clinical Applications)

29
Q

For a while, we thought the ______ did most of the things we know the hypothalamus does

Then, we realized…

-dont think you need to know

A

For a while, we thought the pituitary gland did most of the things we know the hypothalamus does

Then, we realized that the hypothalamus drives the pituitary and is sort of the boss in all of this

30
Q

Which part of the pituitary is connected to the hypothalamus?
***

A

posterior

the posterior portion is an extension of the hypothalamus

31
Q

SCN

  • inpute
  • output
A

-of the Supraoptic/Anterior hypothalamus:

SCN: circadian rhythms; receives input from the retina; can send output to medial preoptic to regulate reproduction

The suprachiasmatic nucleus or nuclei (SCN) is a tiny region of the brain in the hypothalamus, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms.

32
Q

PVN

A

-of the Supraoptic/Anterior hypothalamus

PVN: mostly oxytocin production to regulate lactation, childbirth, and perhaps social relations

  • Oxytocin suggested to be important for pair-bonding, parent-child bonding, and group-bonding
  • Oxytocin released during childbirth to induce and maintain contractions
  • Oxytocin necessary for milk ejection during lactation
33
Q

Milk Ejection- Milk Removal by an Active Process

*

A

1) Mechanoreceptors
2) Spinal Cord –> Lateral Cervical Nucleus
3) Medulla –> Oxytocin neurons

Also, do not forget other stimuli initiating or contributing

34
Q

Feeding Behavior

A

You need food. You need glucose. You just want to make sure you have the right amounts when you need it.

Feeding is the behavior that supplies that energy.

-feeding behavior is pretty complicated
Not controlled by one region specifically of the hypothalamus
The hypothalamus is collecting a lot of information. Wants to make sure in tacking what you need to match your output. Right amount at the right time. Greater demand on energy = more food

(satiety center = VMH)

35
Q

Where does the Mammillothalamic Tract terminate?

A

anterior thalamus

36
Q

What is really important for episodic memory formation ?

A

Fornix

37
Q

Where does the Fornix terminate?

A

Terminates in the mammillary bodies

*Information ultimately gets sent to anterior thalamus via the mammillothalamic tract

38
Q

Ultimate results of stress (due to the hypothalamus?)

A

: Fight or Flight, big changes under long term stress

*Can include: increased heart rate, suppressed digestion, energy mobilization, suppression of immune system and inflammation, suppression of reproductive systems

39
Q

What happens if the Fornix is damaged?

A

inability to form new declarative or episodic memories

40
Q

How does the hypothalamus work indirectly to manage stress response?

A

hormones

41
Q

Major afferent and efferent connections

A
  • Receive information from afferents
  • Ascending sensory signals from brainstem and spinal cord
  • Descending information from the cortex and limbic system
  • Send information through efferents and through hormones
  • Connections to other brain structures
  • Efferents to autonomic nervous system
  • Direct and less direct connection to pituitary
  • Release of hormones
42
Q

in regards to the ventromedial nucleus

  • Stimulate –>
  • Lesion –>
A
  • Stimulate –> cease eating

* Lesion –> overeat and weight gain

43
Q

function of Lateral Hypothalamic Area ***

A

(LHA; feeding center)

  • Arcuate nucleus –> LHA, ventromedial nucleus, paraventricular nucleus, and dorsomedial nucleus
  • No direct interconnections between the VMH and LHA, only those processed through the dorsomedial nucleus
  • sends info to the PVN and DMH
44
Q

Oxytocin ***

A

PVN: mostly oxytocin production to regulate lactation, childbirth, and perhaps social relations

  • Oxytocin suggested to be important for pair-bonding, parent-child bonding, and group-bonding
  • Oxytocin released during childbirth to induce and maintain contractions
  • Oxytocin necessary for milk ejection during lactation
45
Q

vasopressin ***

A

SON: mostly vasopressin production to control water and electrolyte balance

  • Vasopressin controls water retention at the level of the kidney
  • Vasopressin can also kick in if you begin to hemorrhage in an effort to try to increase your blood volume
46
Q

is the Fornix bidirectional?

A

The fornix is both afferent and efferent with respect to the mammillary bodies providing a bi-directional connection with the subiculum of the hippocampal formation.

47
Q

is the mammillothalamic tract bidirectional?

A

The mammillothalamic tract provides a bi-directional pathway connecting the mammillary bodies with the anterior thalamic nucleus.

48
Q

Anterior pituitary communication with hypothalamus

A

Anterior pituitary is not connected to hypothalamus; receives signals (mostly releasing hormones) from hypothalamus via the portal blood supply; releases hormones into general circulation. The actual “gland” part of the pituitary

49
Q

T/F the hypothalamus receives info through efferents and send information through afferents and through hormones

A

FALSE

  • Receive information from afferents
  • Send information through efferents and through hormones
50
Q
  • Endocrine (physiological coordination)
  • By the release :
  • Control (3 things)
  • Regulate (2) secretion.
  • Regulate ______ and ______ release from the _____ pituitary
A
  • Endocrine (physiological coordination)
  • By the release from neurons in various hypothalamic nuclei of specific releasing hormones
  • Control thyroid, adrenal gland and gonads
  • Regulate GH and PRL secretion.
  • Regulate oxytocin (uterine contractions, lactation) and vasopressin (water balance) release from the posterior pituitary
51
Q

The actual “gland” part of the pituitary

A

Anterior pituitary:

52
Q

you begin to hemorrhage

A

Vasopressin, controlled by the SON, can also kick in if you begin to hemorrhage in an effort to try to increase your blood volume

53
Q

hypothalamic afferent fibers

A

The hypothalamus is connected to diverse sites, including the hippocampus, amygdala, brainstem tegmentum, various thalamic nuclei, septal nuclei, and even neocortical areas such as the infralimbic and cingulate cortex. With very few exceptions, these connections are reciprocal.

Systems Neuroscience (24 decks)

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