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APP hypothalamus Flashcards

1
Q

Name the nuclei and their functions

A
  1. Suprachiasmatic nucleus (biological clock, input from light-sensitive retinal ganglion cells).
  2. Anterior hypothalamus (thermoregulation). Fever
  3. Posterior hypothalamic area (sympathetic) - fear and aggression.
  4. Supraoptic/paraventricular nucleus (posterior pituitary secretion oxytocin & Anti-diuretic hormone).
  5. Median eminence/arcuate nucleus/paraventricular nucleus (control of appetite, metabolic rate, anterior pituitary).
  6. Ventromedial nucleus (satiety ‘centre’).
  7. Lateral hypothalamus (hunger ‘centre’); Orexin-hypocretin.
  8. Mammillary body (memory); Korsakov syndrome
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2
Q

Afferents

A

From sensory receptors, visceral (via reticular formation and solitary tract);

from brainstem (locus coeruleus, raphe, periaqueductal
grey);

higher centres (hippocampal formation, amygdala, orbitofrontal cortex via mediodorsal thalamus).

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3
Q

Efferents

A

Endocrine control via posterior pituitary, and anterior pituitary via portal system;

descending control of autonomic centres in brainstem and
spinal cord;

mammillothalamic tract

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4
Q

Blood supply of hypothalamus

A
  • from the internal carotid → gives superior and interior hypophyseal arteries
  • inferior = posterior pituitary directly
  • superior = hypothalamus including the CAPILLARY PLEXUS IN THE MEDIAN EMINENCE from which port veins pass to the anterior pituitary
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5
Q

Death of neurons in which nuclei would lead to diabetes insipidus?

A

SO/PVN

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6
Q

Broadly speaking, what does the hypothalamus have roles in?

A 
Homeostasis 
Rhythms 
Development (e.g. puberty)
Metabolism 
Control of the autonomic nervous system
Endocrine system control
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7
Q

What does the hypothalamus secrete to control the anterior pituitary?

A 
Releasing hormones: 
GnRH
GHRH
TRH
CRH

Inhibiting factors:
DA
Somatostatin

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8
Q

Which two releasing hormones are released from the paraventricular nucleus (also doing OXY and ADH)?

A

CRH and TRH

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9
Q

Which releasing hormone comes from the anterior HT?

A

Somatostatin

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10
Q

How do cells in the SO and PVN know that blood osmolarity has changed?

A

Osmosensitive neurons - osmosensitive neurons in the OVLT, SFO and NTS project directly to SO and PVN

They are sensitive as shrinking + swelling can cause changes in stretch in gated ion channels

Candidate ion channels TRPV1 (hypertonic stimulus), TRPV4 (opens in response to hypotonic stimulus)

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11
Q

Give the pathway leading to ADH release

A

Increased blood osmolarity → OVLT neuron shrinking → TRPV1 open and APs → make connections with SO nuclei → promotes ADH release

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12
Q

What does FSH do?

A

Males - sperm production

Females - follicle ovum maturation

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13
Q

What does LH do?

A

Males - testosterone secretion

Females - ovulation

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14
Q

What does GH do?

A

Growth of tissue and secretion of IGF-1

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15
Q

What does TSH do?

A

Secretion of thyroid hormones which regulate base metabolic rate

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16
Q

What does ACTH do?

A

Secretion of glucocorticoids, mainly cortisol, and production of androgens

17
Q

What does PRL do?

A

Milk production in females

18
Q

What inhibits PRL release?

A

DA

19
Q

Describe the negative feedback loops within the hypothalamus

Give an example

A

The ultra-short feedback loop is mediated by the hypothalamic releasing factors limiting their own release by a type of autocrine effect on targets in the hypothalamus.

Inhibition of releasing-factor secretion by pituitary hormones comprises short loop feedback.

Finally, peripheral hormone inhibition of pituitary secretion comprises the direct long-loop feedback and inhibition on hypothalamic secretion of the releasing factors comprises the indirect long-loop feedback.

The regulation of GHRH release by somatostatin is an example of ultra-short loop feedback, regulation of release by GH is an example of short-loop feedback, and regulation by IGF is an example of indirect long loop feedback.

20
Q

Describe release and role of oxytocin

A

release: stimulated by suckling, & by +ve feedback during labour, as well as by
different sexual stimuli.

In females: induces contractions during labour & lactation, central effects
on food intake & maternal & reproductive behaviour.

Men: influence sexual arousal & ejaculation.

21
Q

What does ADH do?

A

acts on kidney, acts to inc aquaporin expression & insertion to membrane of collecting
duct, inc retention of water in response to either decreased volume or increased osmolarity of
blood.

22
Q

What non-endocrine roles does the hypothalamus play?

A

Food and drink intake
Thermoregulation
Circadian rhythms
(ANS control)

23
Q

Describe the lateral hypothalamic area?

A

‘Hunger centre’

Recieves olfactory input via the medial forebrain bundle

24
Q

Describe the VMN?

A

‘Satiety centre’

Receptors for glucose and FFAs

25
Q

Describe role of arcuate nucleus in food intake?

A

Receptors for leptin (adipose tissue) and insulin

26
Q

What does suckling do to dopamine release?

A

Causes a reduction in the release of DA and therefore an increase in the secretion of prolactin

27
Q

Discuss pituitary tumours

A

most common = GH and PRL = unexpected bone growth and lactation

May have visual field defects - classically, bitemporal hemianopsia, due to optic nerve compression at chiasma

28
Q

Describe Cushing’s

A

Pituitary adenoma - excess ACTH - excess cortisol - can lead to hypertension

29
Q

Adenoma of GH-producing cells

A

Gigantism (before puberty)

Acromegaly (after pubery, disproporitonate growth of hands, jaw and feet)

30
Q

Adenomas of PRH-producing cells

A

Galactorrhoea, amenorrhoea, loss of libido, infertility

31
Q

Discuss effects of hypothalamic lesions on autonomic functions

A

In the eye (pupil, lacrimation); osmotic regulation and cardiovascular
system;
thermoregulation; alimentary system (salivation, peristalsis); genital system
(erection, emission); urinary system; sleep-wake; aggressive behaviour
(sham rage).

32
Q

What part of the hypothalamus is responsible for stimulation of the sympathetic nervous system?

A

Posterior nucleus

33
Q

What part of the hypothalamus is responsible for stimulation of the parasympathetic nervous system?

A

Anterior nucleus

APP (17 decks)

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