Neuroendocrinology Flashcards

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1
Q

What do neuroendocrine cells do and where are they found?

A

Neuroendocrine cells receive neuronal input and secrete hormones in response to that input
Hypothalamus and Pituitary gland

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2
Q

Where are parvocellular and magnocellular neurons found?

A

Hypothalamus

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3
Q

Where do parvocellular neurons project to?

A

Parvocellular neurons –> Hypophyseal system –> Anterior pituitary

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4
Q

Where do magnocellular neurons project to?

A

Posterior pituitary. (Larger neuronal axons than parvocellular neurons so can just project directly to posterior pituitary)

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5
Q

From the anterior pituitary and posterior pituitary, where do hormones travel next?

A

General circulation –> target tissues, adrenal, thyroid, gonads

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6
Q

What is the function of the hypothalamus?

A

Integrates ANS signals and endocrine function with behaviour. Regulates behaviour concerned with basic homeostatic requirements of everyday life

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7
Q

What are the three types of processes by which homeostasis can be controlled?

A
  • Behavioural responses​
  • Neuronal control through ANS
  • Hormonal control via the pituitary gland
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8
Q

Give 6 homeostatic functions controlled by the hypothalamus

A

1) Blood pressure and electrolyte composition - control of drinking and salt appetite and control of blood osmolality and vasomotor tone​
2) Body temperature - metabolic thermoregulation and behaviours like seeking an appropriate environment​
3) Energy metabolism - feeding, digestion, metabolic rate​
4) Reproduction - hormonal control of mating, pregnancy and lactation​
5) Stress response - adrenal stress hormones​
6) Growth - growth hormone

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9
Q

What does the paraventricular nucleus control? By secreting which hormones?

A
Stress (CRH)​
Metabolism (TRH)​
Osmoregulation (ADH)​
Blood pressure (ADH)​
Maternal control (Oxy.)​
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10
Q

What does the arcuate nucleus control? By secreting which hormones?

A

Reproduction (GnRH) ​
Growth (GHRH)​
Lactation (Dopamine)​

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11
Q

What does the supraoptic nucleus control? By secreting which hormones?

A
Osmoregulation (ADH)​
Blood pressure (ADH)​
Maternal control (Oxy.)​
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12
Q

Where is the pituitary gland found?

A

Located in a cavity within the sphenoid bone at the base of the brain called the sella turcica. The pituitary gland is connected to the hypothalamus through the pituitary stalk (infundibulum)

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13
Q

Describe some differences between anterior and posterior pituitary

A
  • Anterior develops from pharyngeal epithelium/ Posterior develops from neuronal tissue
  • Anterior contains glandular cells/ Posterior contains axon terminals
  • Anterior receives signal from parvocellular neurons/ Posterior involves magnocellular neurons
  • Anterior responds to factors from portal system/ Posterior does not have portal system
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14
Q

What does Corticotropin releasing hormone (CRH) act on?

A

Acts on corticotrophins in anterior pituitary which then release ACTH which acts on adrenal gland.

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15
Q

What does Thyrotropin releasing hormone (TRH) act on?

A

Acts on thyrotrophs in anterior pituitary which release TSH which acts on thyroid gland

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16
Q

What does gonadotropin releasing hormone (GnRH) act on?

A

Acts on gonadotrophs in the anterior pituitary which then release LH, FSH which act on the gonads

17
Q

What does growth hormone releasing hormone (GHRH) act on?

A

Somatotrophs in anterior pituitary which then release growth hormone which acts on all tissues

18
Q

What does prolactin inhibiting hormone (dopamine) act on?

A

Lactotrophs in anterior pituitary which then release prolactin which act on breasts

19
Q

What determines release of growth hormone?

A

Release of growth hormone is determined by the balance between growth hormone releasing hormone (GHRH) and growth hormone inhibiting hormone (GHIH or somatostatin) received through the portal system

20
Q

What regulates the release of prolactin?

A

Regulation of prolactin release is through inhibition by dopamine, rather by a releasing hormone​
Prolactin itself enhances dopamine secretion, creating ‘short loop’ negative feedback (i.e. without a downstream hormone as in the three axes)​

21
Q

Describe the cell types found in the posterior pituitary

A

The posterior pituitary gland contains the unmyelinated axons of magnocellular neurones projecting down from the paraventricular and supraoptic nuclei​.
It also contains astrocyte-like neuroglial cells called pituicytes, with cytoplasmic processes that surround the axons.

22
Q

What hormones are released by the posterior pituitary?

A

The posterior pituitary gland releases antidiuretic hormone (arginine vasopressin) and oxytocin​.
Both hormones are produced by both hypothalamic nuclei (supraoptic nuclei and paraventricular nuclei) (to some extent), but they are produced by separate cell types​.

23
Q

How are posterior pituitary hormones processed?

A

Antidiuretic hormone and oxytocin are small peptide hormones synthesised as larger precursors in cell bodies in the hypothalamus​.
These are packaged into vesicles, processed into the mature hormone and bound to carrier proteins called neurophysins​.
The hormone-neurophysin complex is transported along the neuronal axon and temporarily accumulates at Herring bodies​.
The hormone-containing vesicles fuse with the cell membrane in response to action-potential associated Ca2+ influx, releasing the hormone​.
The hormone dissociates from the neurophysin (carrier), which has no further function​.

24
Q

How are posterior pituitary hormones processed?

A

Antidiuretic hormone and oxytocin are small peptide hormones synthesised as larger precursors in cell bodies in the hypothalamus​.
These are packaged into vesicles, processed into the mature hormone and bound to carrier proteins called neurophysins​.
The hormone-neurophysin complex is transported along the neuronal axon and temporarily accumulates at Herring bodies​.
The hormone-containing vesicles fuse with the cell membrane in response to action-potential associated Ca2+ influx, releasing the hormone​.
The hormone dissociates from the neurophysin (carrier), which has no further function​.