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SGUL - Physiology 1 > Pituitary Gland and Its Disorders > Flashcards

Pituitary Gland and Its Disorders Flashcards

1
Q

The pituitary gland has a dual blood supply.

What are these supplies?

A
  • first is via long and short pituitary arteries
  • second is from hypophyseal portal circulation (begins as a capillary plexus around Arc)
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2
Q

What 6 hormones are released from the anterior pituitary, and what is their role?

A
  • Adrenocorticotrophic hormone (ACTH): regulation of adrenal cortex
  • Thyroid-stimulating hormone (TSH): thyroid hormone regulation
  • Growth hormone (GH): growth
  • Luteinising hormone (LH) and Follicle-stimulating hormone (FSH): reproductive control
  • Prolactin (PRL): breast milk production
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3
Q

What 2 hormones are released from the posterior pituitary, and what is their role?

A
  • Anti-diuretic hormone (ADH) - osmoregulation
  • Oxytocin: breast milk formation and uterine contractions
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4
Q

What are some different types of pituitary tumours?

A

HORMONE HYPERSECRETION
SPACE-OCCUPYING LESION:
- headaches
- visual loss (field defect)
- cavernous sinus invasion
HORMONE DEFICIENCY STATES:
- interfere with the surrounding normal pituitary

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5
Q

Tumours of the anterior pituitary can cause syndromes of hormone excess.
List the syndrome associated with the overexpression of each hormone from the anterior pituitary.

A

GH: Acromegaly
ACTH: Cushing’s Disease
TSH: Secondary thyrotoxicosis
LH/FSH: (non-functioning pituitary tumour)
PRL: Prolactinoma

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6
Q

Describe the control of growth hormone. PART 1

A
  • Stimulatory hormone (GHSH) and inhibitory hormone (somatostatin).
  • GH is released in pulses
  • GH acts on the liver to produce certain growth factors e.g IGF-1, which causes long bone growth for linear growth.
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7
Q

Describe the control of growth hormone. PART 2

A
  • Negative feedback is mainly supplied by the IGF-1.
  • When there is pituitary tumour producing too much GH, affects our growth and metabolism.
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8
Q

What are some systemic effects of GH/ IGF-1 excess? PART 1

A
  • Increased skin thickness
  • Increased sweating
  • Impaired glucose tolerance
  • Diabetes mellitus
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9
Q

What are some systemic effects of GH/ IGF-1 excess? PART 2

A
  • Insulin resistance
  • Reduced total cholesterol
  • Increased triglycerides
  • Increased nitrogen retention
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10
Q

What are some consequences of GH/IGF-1 excess?

A
  • Cardiomyopathy (diseases of the heart muscle)
  • Hypertension
  • Bowel polyps (small growths)
  • Arthropathy (disease of a joint)
  • OSA (obstructive sleep apnoea)
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11
Q

List some actions of cortisol on energy metabolism.

A
  • increased gluconeogenesis/glycogenolysis
  • decreased glucose utilisation
  • increased glycogen storage
  • increases lipolysis
  • protein catabolism
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12
Q

List some other effects of cortisol.

A
  • maintains BP
  • anti-inflammatory effects.
  • increased gastric acid production.
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13
Q

What happens as a result of Cushing’s Syndrome due to changes in fat metabolism?

A
  • change in body shape
  • central obesity
  • thin skin, easy bruising
  • osteoporosis (brittle bones)
  • diabetes
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14
Q

What happens as a result of Cushing’s Syndrome due to changes in sex hormones and salt and water retention?

A
  • excess hair growth
  • irregular periods
  • impotence
  • high blood pressure
  • fluid retention
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15
Q

List some drugs that interfere with dopamine and prolactin secretion.

A
  • antiemetics (effective against vomiting and nausea)
  • antipsychotics
  • oral contraceptives/ hormone replacement therapy
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16
Q

What are some features of prolactin excess (hypogonadism)?

A
  • infertility
  • oligoamenorrhoea (irregular menstrual periods)
  • amenorrhoea (no menstrual periods)
  • galactorrhoea (milky discharge from breasts)
17
Q

What is the treatment for prolactinomas?

A

Dopamine agonists (such as bromocriptine and cabergoline), not surgery.

18
Q

Describe non-functioning pituitary tumours.

A
  • No syndrome or hormone excess is produced
  • Can cause symptoms due to space occupation (headaches, visual field defects)
  • Treatment would be surgery - no effective medical therapy
19
Q

What are possible treatments for pituitary adenomas? PART 1

A

SURGERY:
- transsphenoidal (through nose and sphenoid bone)
- adrenalectomy
RADIOTHERAPY (slow)

20
Q

What are possible treatments for pituitary adenomas? PART 2

A

DRUGS:
- block hormone production and stop hormone release

21
Q

List some causes of pituitary failure.

A
  • tumour
  • trauma
  • infection
  • inflammation (sarcoidosis [the abnormal collection of inflammatory cells], histiocytosis [excessive number of tissue macrophages])
  • iatrogenic (illness caused by medical examination/ treatment)
22
Q

What are the effects of hypopituitarism? PART 1

A

It affects the thyroid:
- bradycardia
- weight gain
- cold intolerance
- hypothermia

23
Q

What are the effects of hypopituitarism? PART 2

A

It affects sex steroids:
- oligomenorrhoea
- reduced libido
- reduced body hair

24
Q

What are the effects of hypopituitarism? PART 3

A

Reduces cortisol:
- tiredness
- weakness
- postural hypotension
- myalgia (pain in a muscle)

Reduces GH:
- tired
- central weight gain

25
Q

What would be the treatment for hypopituitarism?

A
  • For the thyroid effects, we would give thyroxine.
  • For the sex steroid effects, we would give testosterone and oestrogen.
  • For the reduced cortisol, we would give hydrocortisone.
  • For the reduced GH, we would give GH.
26
Q

What does vasopressin control?

A

CONTROL:
- increased plasma osmolality
- decreased BP (baroreceptors)
- decreased PaO2, increased PaCO2 (cortisol, sex steroids, angiotensin II)

27
Q

Where does vasopressin act on?

A
  • Collecting ducts, to increase permeability for H2O for the reabsorption of free water
  • Vasoconstriction of blood vessel
28
Q

Describe SIADH

A
  • Too much ADH.
  • Caused by a brain injury/ tumour, lung cancer or infection or metabolic cause such as hypothyroidism or Addison’s.
29
Q

How can SIADH be diagnosed and treated?

A

Checking bodily fluids for:
- low plasma Na+
- low plasma osmolality
- high urine osmolality
- high urine sodium

Treatment would involve fluid restrictrion.

30
Q

Describe Diabetes Insipidus

A

Underproduction of ADH in the body. The patients urinate until they dehydrate themselves.
- 2 main causes:
- CRANIAL - lack of ADH production
- NEPHROGENIC - receptor resistance

31
Q

How would Diabetes Insipidus be diagnosed?

A

Checking body fluids:
- polyuria [excessive urinating] (more than 3L)
- polydipsia [excessive thirst] (increased Na+, increased plasma osmolality, decreased urine osmolality, decreased urine Na+)

32
Q

What are the 2 functions of the hypothalamus?

A

→ it takes sensory input - electrical signal
→ and produces hormones to adapt to the physical state - chemical signal

33
Q

What is the negative feedback system in endocrinology?

A

→ The production of the end hormone stops the pituitary and hypothalamus producing more

34
Q

How is prolactin controlled?

A

→ The stimulus to production of milk is an external signal
→ Intrinsic high production of prolactin from the pituitary
→ Tonic inhibitory dopamine signal from the hypothalamus to the pituitary

35
Q

How does lactation occur?

A

→ mechanical stimulation of the nipple sends a neuronal signal to the brain
→ goes to the hypothalamus
→ switches off dopamine production

36
Q

What is homologous vision?

A

→ Nasal fibres from the same side cross and line up with temporal fibres on the other side
→ Go into one piece back to the brain for interpretation

37
Q

Where is the optic chiasm?

A

Above pituitary

38
Q

What is bitemporal hemianopia?

A

→ Partial blindness
→ Vision is missing in the outer half of both right and left visual field

39
Q

What rises when a tumor is made?

A

→ prolactin
→ obstructs the pituitary and stops dopamine coming in the brain

SGUL - Physiology 1 (68 decks)

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