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Brain And behaviour (BIBB109) > Hypothalamus > Flashcards

Hypothalamus Flashcards

1
Q

How does the hypothalamus mediate homeostasis?

A

It controls:

1) autonomic nervous system (projections to sympathetic and parasympathetic neurons)
2) endocrine system: via anterior and posterior pituitary gland
3) motivated homeostatic behaviors (feeding, drinking,…)

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2
Q

What is the organization of the hypothalamic nuclei?

A

Divided into 3 regions from medial to lateral:

1) periventricular area: periventricular nucleus (subchiasmic nuclei)
2) medial hypothalamic area: (cortex, hindbrain)
3) lateral hypothalamic nuclei: (cortex, hindbrain)

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3
Q

What is the organization of the medial hypothalamic area?

A

4 regions from rostral to caudal

1) Preoptic area
2) anterior (supraoptic) region
3) middle (tuberal) region
4) posterior (mammillary) region

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4
Q

How does the hypothalamus control the posterior pituitary?

A

Magnocellular neurosecretory cells located in the supraoptic nucleus and the paraventricular nucleus.

They secrete two hormones into the capillary bed in the posterior pituitary:

Oxytocin - love, social bonding

Vasopressin - water retention, less urine production

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5
Q

How does the hypothalamus control the anterior pituitary?

A

Parvocellular neurosecretory cells located in the paraventricular nucleus

They secrete releasing hormones into the hypothalamic-pituitary portal circulation

Receptors for hypothalamic hormones cause anterior pituitary cells to release or stop releasing their hormones into blood

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6
Q

What is released during stress response? What does this element do?

A

Release of cortisol

Cortisol:

  • releases glucose into your bloodstream
  • increases blood pressure for increased physical activity
  • stimulates brain for more intense awareness
  • immune system activity is reduced to save energy for physical activity
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7
Q

What is the HPA axis?

A

1) stress
2) Parvocellular neurosecretory neurons release corticotropin-releasing hormones (CRH)
3) Anterior pituitary releases ACTH (adrenocorticotropic hormone)
4) ACTH acts on adrenal cortex which releases cortisol
5) cortisol inhibits CRH release

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8
Q

What is the difference btw sympathetic and parasympathetic?

A

Sympathetic: fight or flight

Parasympathetic: rest and digest

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9
Q

What does the ANS innervate?

A

Smooth muscle, cardiac muscle, gland cells

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10
Q

Explain what anabolism and catabolism are

A

Anabolism: when the blood is filled with nutrients

Catabolism: during fasting; between meals

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11
Q

How is energy stored?

A

2 forms: glycogen in liver and skeletal muscle

Triglycerides in adipose tissue (fat)

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12
Q

How does the adipose tissue communicate with brain?

A

Ob gene codes for a protein called leptin which is released by adipocytes (fat cells)

Leptin is a hormone that communicates with the brain about fat reserves:

  • elevated leptin levels in blood activates hypothalamus and decreases feeding behavior
  • decreased leptin levels in blood activates hypothalamus and increased feeding behavior
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13
Q

What do Ob-/Ob- mice lack? Conséquence?

A

Both copies of the gene and the mice are obese: brain thinks fat reserves are low

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14
Q

How does leptin interact with hypothalamus? What does the*** control?

A

Leptin activates leptin receptors on neurons in Arcuate nucleus of hypothalamus

The arcuate nucleus controls paraventricular nucleus (ANS, endocrine system) and the lateral hypothalamic area (activates homeostatic motivated behavior = feeding)

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15
Q

What are the effects of elevated leptin levels in hypothalamus?

A

Elevated leptin levels lead arcuate neurons to the release of peptide transmitters called alphaMSH and CART. They inhibit feeding behavior

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16
Q

What do decreased leptin levels entail?

A

Arcuate neurons responding to decreased levels of leptin release the peptide transmitters NPY and AgRP which stimulate feeding behavior

17
Q

What are the 4 modulatory systems?

A

Norepinephrine system
Serotonin system
Acetylcholine system
Dopamine system

18
Q

Explain the norepinephrine system (Origin, Target, What it’s involved in)

A

NE

Origin: locus coerulus in pons
Target: Most of CNS
Activated by new, unexpected stimuli
Controls: attention, arousal, sleep-wake

19
Q

Explain the serotonin system

Origin, Target, What it’s involved in

A

5-HT

Origin: raphe nuclei in brainstem
Target: Most of CNS
Part of Reticular Activating System, involved in wakefulness and sleep
Controls arousal, sleep-wake, pain, mood
LSD acts similar to it, simulates dreams while awake

20
Q

Explain the acetylcholine system for memory (Origin, Target, What it’s involved in)

A

ACh

Origin: basal forebrain complex—> arousal, sleep wake, learning and memory
Target: Cerebral cortex + Hippocampus
first cells to die in Alzheimer’s

21
Q

Explain the dopamine system in movement (Origin, Target, What it’s involved in)

A

DA

Origin: substantia nigra
Controls the facilitation of initiation/inhibition of movement, death of cells leads to Parkinsons

22
Q

Explain the dopamine system in reward (Origin, Target, What it’s involved in)

A

Origin: Ventrotegmental Area (VTA)
Target: Nucleus accumbens, frontal cortex
Involved in reward and reinforcement, learning and memory
Cocaine, amphetamines act on this, serving as reuptake inhibitor

23
Q

Diffuse Modulatory System

A

Within brain, 4 modulatory NT’s, cell body in brainstem, NT release diffused throughout extracellular fluid, widespread influence.

24
Q

Explain the acetylcholine system for sensory input (Origin, Target, What it’s involved in)

A

ACh

Origin: Pontomesencephalotegmental cortex
Target: Dorsal Thalamus
Involved in: Organizing sensory Input

25
Q

Autonomic Nervous System

A
  • One switch that turns on and off, activating a network all connected to various points.
  • Regulates smooth/cardiac muscle and glands (mostly involuntary)
  • Through sympathetic/parasympathetic/enteric division
  • There isn’t much of a fine tuning.
26
Q

Sympathetic Division: uses, where and NT’s used

A
  • 4 F’s (fight, flight, fear, sex)
  • Pre Ganglionic: ACh, Post Ganglionic: NT
  • Thoracic/Lumbar (Think of running, punching, HR regulation)
27
Q

Parasympathetic Division: uses, where and NT’s used

A
  • Digestion, resting, recovering
  • Both ACh for pre and post ganglion
  • Cervical/Sacral (think of crapping)
28
Q

Enteric Division

A
  • “Gut brain”

- Neurons in GI Tract, embedded in smooth muscle and help food move along

Brain And behaviour (BIBB109) (28 decks)

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