Pituitary Gland Flashcards by Chavez Kamal

Hormones produced by: Placenta

produces oestrogen, progesterone and human chorionic gonadotrophin

How well did you know this?

Not at all

Perfectly

Hormones produced by: Kidney

produces three important hormones: erythropoietin, calcitriol and renin. They also synthesize prostaglandins, which affect many processes in the kidneys.

How well did you know this?

Not at all

Perfectly

Hormones produced by: GIT

gastrin and cholecystokinin

How well did you know this?

Not at all

Perfectly

Hormones produced by: Graafian follicle

progesterone

How well did you know this?

Not at all

Perfectly

Hormones produced by: Corpus luteum

produces high levels of progesterone, moderate levels of estradiol, inhibin A and small amounts of oestrogen

How well did you know this?

Not at all

Perfectly

Hormones produced by: Interstitial cells of Leydig in the testis

produce testosterone in presence of luteinizing hormone (LH)

How well did you know this?

Not at all

Perfectly

Hormones produced by: Thymus

secretes thymosin, a hormone necessary for T cell development and production

How well did you know this?

Not at all

Perfectly

Hormones produced by: Hypothalamus

Hormone releasing factors [Thyrotropin-releasing hormone (TRH), Gonadotropin-releasing hormone (GnRH), Growth hormone-releasing hormone (GHRH), Corticotropin-releasing hormone (CRH), Somatostatin]. Antidiuretic hormone or vasopressin and oxytocin.

How well did you know this?

Not at all

Perfectly

Where is pituitary gland ?

Situated in the hypophyseal fossa on the superior surface of the body of the sphenoid
Suspended from the floor of the third ventricle by a narrow stalk called infundibulum
It is enclosed by the dural sheath, its roof is formed by diaphragma sellae, which is perforated by the infundibulum

How well did you know this?

Not at all

Perfectly

Development of Pituitary Gland :

Rathke’s pouch or hypophysial diverticulum appears approximately at the end of 3rd week, as an evagination of the oral cavity, which grows dorsally towards the infundibulum or neurohypophysial diverticulum.
By the end of 2nd month it loses its connection with the oral cavity
Later it comes in close contact with the infundibulum

How well did you know this?

Not at all

Perfectly

Function of Pineal Gland :

-synthesize melatonin, serotonin, and cholecystokinin.
-Daylight reduces the synthesis and secretion of melatonin by the pineal gland; darkness increases the synthesis and release of melatonin
-Melatonin probably holds back the reproductive development until a suitable age has reached by inhibiting the secretion of gonadotrophic hormones
-The gland acts as a biological clock for physiological and behavioral control.

How well did you know this?

Not at all

Perfectly

Clinical Function of Pineal Gland:

Lesion of the pineal gland is associated with precocious puberty [body changes happen earlier than normal]

How well did you know this?

Not at all

Perfectly

Microscopic structure of Pituitary Gland:
Function of Acidophils (Alpha Cells) :

They contain eosinophilic granules and secrete growth hormone (somatotrophes) and lactogenic hormone (lactotropes) or prolactin

How well did you know this?

Not at all

Perfectly

Microscopic structure of Pituitary Gland:
Function of Basophils (Beta Cells) :

Secretory granules in the cytoplasm are basophilic in nature. These cells secrete thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone and adrenocorticotrophic hormone.

How well did you know this?

Not at all

Perfectly

Microscopic structure of the Pituitary gland: Function of Pars intermedia:

-Between the neurohypophysis and pars distalis.
-They secrete melanocyte-stimulating hormone (MSH)

How well did you know this?

Not at all

Perfectly

Microscopic structure of the Pituitary gland: Function of Neurohypophysis or Pars nervosa:

The vasopressin or ADH and oxytocin secreted by these nuclei are transported by the nerve fibres of the hypothalomohyphyseal tract, and stored in the nerve terminals as Herring bodies

Hypophysial portal system:
It consists of two sets of capillaries

One in the hypothalamus (median eminence)
Other in the hypophysis cerebri (sinusoids of pars posterior)

Blood supply of the pituitary gland

-Superior hypophyseal arteries comes from the internal carotid, anterior cerebral or middle cerebral artery
-Inferior hypophyseal artery comes from internal carotid artery
-Veins drain into neighbouring dural venous sinuses, mainly cavernous and intercavernous sinuses. The venous blood carries the hormones from the gland to the sites of their action.

Cells present in Pars intermedia

Basophils Cells

Cells present in pars anterior:

Acidophils and Basophils Cells

Hypothalamic-Pituitary unit
It comprises of two neurosecretory tracts:

Supra-optic hypophyseal tract
Tubero-infundibular tract

Cells present in the pars posterior

Supraoptic and Paraventricular nucelous of hypothalamus

Function of The supra-optic hypophyseal tract:

consists of fibres arising from the supra-optic and paraventricular nucleus that projects to the neurohypophysis and

-It carries neurosecretory granules, oxytocin and vasopressin or ADH by axonic transport

Function of the tubero-infundibular tract:

arises from the tuberal region of the hypothalamus, and can be traced only till the median eminence and the infundibular stem.
-Fibres of this tract carry the hormone releasing factors to the anterior lobe via the portal system

What are Pituitary tumors and how is it started:

Pituitary adenomas arising from its chromophobe cells -these cells are the most common cause of pituitary hormone hyper-secretion and hyposecretion syndromes in adults.

Pituitary adenoma produces two types of symptoms

- Symptoms due to pressure on adjacent structures - Symptoms due to endocrine disturbances

What are cause of Craniopharyngiomas:

derived from pituitary gland embryonic tissue – DerivedfromRathke’spouch – Large,cystic,and locally invasive – Many are partially calcified

Causes of Pituitary metastases:

– Exclusively in the posterior pituitary. – Mainly from breast cancer. – Diabetes insipidus can be a presenting feature of lung and breast metastases.

Cause of ↑ GH :

adenoma of the acidophils (excessive secretion of GH) results in gigantism before puberty and acromegaly (abnormal growth of hands, feet and face) in adults

Cause of ↑ Prolactin :

-amenorrhoea: absence of menstrual period in a women of reproductive age -Galactorrhoea: spontaneous flow of milk from the breast - Impotence

Cause of ↑ ACTH :

Basophil adenoma (excessive secretion of ACTH) causes Cushing’s syndrome

Cause of Diabetes insipidus:

develops when The posterior pituitary no longer releases adequate amounts of ADH)

Cause of ↑ TSH :

Hyperthyroidism

What is. Hypopituitarism?

sequential loss of hormone secretion

Cause of GH deficiency :

Non-secretary (chromophobe) adenoma dwarfism in children

Cause of Disorders of Posterior Pituitary

- Lesion of the hypothalamus, which destroy the neurosecretory cells that produce ADH * loss of renal capacity to concentrate urine. * individual suffers from polyuria, excessive thirst & polydipsia.

What would occur from Pressure on the cavernous sinus :

Exophthalmos or proptosis – bulging of the eye anteriorly out of the orbit, can be bilateral or unilateral Ophthalmoplegia – paralysis of one or more extraocular muscles responsible for eye movement [3rd, 4th, and 6th cranial nerves] (i) 3rd nerve being near the pituitary, may be pressed upon producing diplopia (ii) 4th or 6th nerve palsy (Strabismus/diplopia) -Proptosis (exophthalmos or proptosis, or exorbitism) is a bulging of the eye anteriorly out of the orbit. (iv) Pressure upwards may close the foramen of Monro - hydrocephalus