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ANAT3022 > Lecture 12, 13, 14 - Hypothalamus > Flashcards

Lecture 12, 13, 14 - Hypothalamus Flashcards

1
Q

The hypothalamus is REGIONALLY divided into: (x4)

name the nuclei contained in each region [total=12]

A
  • preoptic region (medial & lateral preoptic nuclei)
  • supraoptic region (ant. hypothalamic, supraoptic, suprachiasmic, paraventricular)
  • tuberal region (Dorso & ventromedial, arcuate, infundibulum)
  • mammillary region (mammillary bodies, posterior hypothalamic)
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2
Q

the hypothalamus is FUNCTIONALLY divided into:

A
  • lateral
  • middle
  • periventricular
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3
Q

The fornix divides which two hypothalamic functional zones?

A

middle and lateral

periventricular -> middle [FORNIX] -> lateral

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4
Q

what are the functions of the PERIVENTRICULAR zone (x1)

A
  • regulates release of endocrine hormones from ANTERIOR pituitary gland
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5
Q

What are functions of the middle zone (x3)

A
  • regulating release of OXYTOCIN & VASOPRESSIN from POSTERIOR pituitary gland
  • regulates autonomous system
  • sets biological rhythm of organism
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6
Q

which hypothalamic nucleus regulates the organism’s biological rhythm?

A

suprachiasmic

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7
Q

What are functions of the LATERAL zone ? (x3)

A
  • regulating sleep-wakefullness
  • regulating feeding cycle
  • integrates information from other hypothalamic nuclei and cortical structures engaged in emotions
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8
Q

The hypothalamus is supplied by which artery?

A

the hypothalamic branch of the posterior communicating artery

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9
Q

What is the Blood-brain barrier? What are its functions?`

A
  • a semi-permeable barrier which protects the blood flow from brain extracellular fluid (BECF) that is unique to the CNS.
  • made from astrocytes and endothelial cells joined by tight junctions which line the interior of CNS arteries.
  • allows passage of water molecules, some gases, lipid soluble substances, amino acids and glucose.
  • not present on circumventricular organs
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10
Q

What are circumventricular organs? (dont list them yet)

A
  • organs which are located around the border of the ventricles,
  • extensive vasculature but ‘leaky’ BBB
  • alternate route for hormone secretion into bloodstream

-

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11
Q

List the circumventricular organs (divide into the two types)

A

SENSORY ORGANS: sense plasma molecules in bloodstream and convey info to other brain regions for DIRECT COMMUNICATION between ANS and systemic circulation

  • subfornical organ
  • area postrema
  • vascular organ of lamina terminalis

SECRETORY ORGANS: secrete hormones and glycoproteins to peripheral bloodstream in repsonse to internal (brain) and external stimuli

  • Pineal gland
  • Neurohypophysis (post. pituitary gland)
  • sub commissural organ
  • intermediate lobe of pituitary gland
  • median eminence
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12
Q

all CVO’s EXCEPT ____ feature extensive vasculature with ___ capilliaries, causing a “leaky” BBB

A

SCO (sub commissural organ)

fenestrated (perforated, presence of apertures)

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13
Q

The Sella Turcica and Diaphram Sellae are both

A

dural reflections which encase the pituitary gland

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14
Q

The hypophysis and hypothalamus together secrete a total of ___ hormones (__each), to regulate all aspects of ____(x4)

A
  • 16
  • pit = 7, hyp = 9
  • growth, metabolism, development, homeostasis
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15
Q

the anterior pituitary gland is known as___and posterior is known as ____

A
  • adenohypophysis

- neurohypophysis (contains neuronal axons from hypothalamus)

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16
Q

The adenohypophysis (distal, intermediate) is formed from___ and the neurohypophysis is formed form the ____

A
  • ectodermal endothelium of roof of mouth

- nerve tissue of floor of diencephalon

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17
Q

Which lobe of the pituitary gland is PART of/DEVELOPS from the hypothalamus?

A

neuro/posterior (forms from floor od diencephalon aka hypothalamus)

18
Q

what are hormones released by the adenohypophysis called?

A

tropic hormones/ tropics

19
Q

What does the adenohypophysis do?

A
  • secretes and releases tropic hormones

- regulated by hypothalamus

20
Q

how does the hypothalamus regulate the secretion and release of hormones from the adenohyp.?

A

by releasing hypothalamic releasing/inhibiting hormones into the PRIMARY PLEXUS of the HYPOPHYSEAL PORTAL SYSTEM, which travels to the SECONDARY PLEXUS via the PORTAL VEINS, stimulating hormone release into the circulation.

21
Q

how is the portal system different from normal blood flow?

A

NORMAL:
heart -> artery -> capillary -> vein -> heart

PORTAL SYSTEM:
heart -> artery -> capillary network -> portal vein ->2nd capilary network -> vein -> heart

22
Q

what are Somatrophs?

A
  • they are hormone secreting neurons of the adenohypophysis which secrete SOMATOTROPIN or HUMN GROWTH HORMONE (hGh).
  • they are the most plentiful endocrine cell in the anterior pituitary.
23
Q

Hypoglycemia increases production of ___

hyperglycemia increases production of__

A
  • GHRH (growth hormone releasing hormone)

- GHIH

24
Q

high amount of hGH (human growth hormones) increases?

A

blood-glucose level

25
Q

describe the functions and properties of the neurohypophysis

A
  • posterior pituitary gland
  • part of hypothalamus
  • does NOT secrete hormones
  • STORES & RELEASES hormones
    • oxytoncin, vasopressin
  • contains axons from hypothalamus
26
Q

The neurohypophysis recieves axons (thus hormones) from which two hypothalamic nuclei?

A
  • paraventricular (oxytocin)

- supraoptic (vasopressin)

27
Q

The adenohypophysis receives blood supply from the ___and drained by the ____.

the neurohypophysis recieves blood from the ___ and is drained by the ____.

A
  • superior hypophyseal artery
  • anterior hypophyseal vein
  • inferior hyp. artery
  • posterior hyp. vein
28
Q

The adenohypophysis is part of the parvocellular or magnocellular neurosecretory system?

A
  • parvocellular
29
Q

the hypothalamus has 5 afferent projections. What are they and where do they originate (specifically) and which nuclei do they terminate?

A
  • fornix (from SUBICULAR CORTEX of hippocampal formation to ANTERIOR NUCLEUS OF THALAMUS, MEDIAL HYPOTHALAMUS & MAMMILLARY BODIES)
  • stria terminalis (from medial amygdala to medial hypothalamus & Bed nucleus)
  • ventral amygdalofugal pathway (from basolateral amygdala to lateral hypothalamus and midbrain)
  • Medial forebrain bundle (septal area)
  • retinohypothalamic fibres (retina)
30
Q

what are two efferent projections from the Hypothalamus?

A
  • mammillothalamic (mammillary bodies -> anterior nucleus of thalamus, control of emotional expression part of papez circuit)
  • mammillotegmental (mammillary bodies -> midbrain tegmentum, for hypothalamic control of autonomic systems)
31
Q

Which three pathways allow hypothalamic control of the ANS?

A
  • Dorsal longitudinal fasciculus
  • medial forebrain bundle
  • mammillotegmental pathway
32
Q

Which hypothalamic nucleus gives rise to the DLF and where does this pathway innervate? what is its function?

A
  • paraventricular nucleus
  • along brainstem and all levels of spinal cord
  • mediate sympathetic & parasympathetic NS
33
Q

Which hypothalamic nucleus gives rise to the MFB and where does this pathway innervate? what is its function?

A
  • paraventricular nucleus (incl. fibres from basal forebrain and septal nuclei)
  • same as DLF
  • mediate sympathetic & parasympathetic NS
34
Q

Which hypothalamic nucleus gives rise to the Mammillotegemental tract and where does this pathway innervate? what is its function?

A
  • mammillary bodies
  • autonomic nuclei of brainstem (pontine & midbrain reticular formation)
  • mediate ONLY parasympathetic NS
35
Q

What are paravertebral/sympathetic chain ganglia?

A
  • chains of ganglia of the sympathetic NS, which exist next to the spinal cord.
  • fibres from the spinal cord, which enter these ganglia are called PREGANGLIONIC fibres
  • fibres that exit these ganglia to innervate visceral organs are called POST-GANGLIONIC fibres.
  • the existence of this chain allows for preganglionic fibres to travel vertically through the chain and innervate higher or lower levels of the spinal cord.
36
Q

does the sympathetic nervous system INCREASE or DECREASE blood-sugar level?

A

INCREASE

37
Q

what is the major difference between parasympathetic and sympathetic nervous systems?

A

the effects of the parasympathetic NS are LOCALISED and TEMPORARY

38
Q

Which hypothalamic nucleus is the MASTER BIOLOGICAL CLOCK?

A

SCN - suprachiasmic nucleus

  • synchronises inner clock with environmental/social clock
  • follows circadian rhythm (24hrs)
39
Q

the SCN always communicates with other hypothalamic nuclei via the ___

A

PVN

40
Q

which neurotransmitter is MOST used by the SCN?

A

GABA

41
Q

explain the concept of melatonin release during day and night

A

DAY:

daylight EXCITES GABAergic neurons in the SCN hence, inhibiting neurons which communicate with the PVN, leading to inhibited melatonin production.

NIGHT:
lack of light DOES NOT excite inhibitory function of GABAergic neurons in the SCN, hence excitatory neurons project to PVN which then encourage production of melatonin.

ANAT3022 (13 decks)

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