Physiology In The Human Skull Biology Essay


In the human skull and at the base of the brain, are the locations of the pituitary gland which is small gland that look like a bean shaped. Its sits behind the bridge of the nose. (Mayfield clinic, 2009) These glands are divided into three sections which are known as anterior lobe, intermediate lobe and the last one is posterior lobe. These entire three lobes secreted different type of hormones that will controls different type of function in human body. (Regina Bailey, nd) Pituitary gland is responsible to control the functions of entire other endocrine glands in the body and that's why this gland known or called as a master gland. (Alice Brown, 2011)

There are six major hormones that are secreted by the anterior lobe. Every type of hormones secreted produces different type of functions which affects our body.

Growth hormone (GH)

Helps to control body growth in human body as well as for maintaining the composition of a healthy body especially for the bone mass and the muscle mass. (Alice Brown, 2011)

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Prolactin hormone

Stimulate breast development to produce milk for nursing purposes. It is also affects the sex hormone level for sexual satisfactions and relaxation in man and women, which is being an indicator. (Wikipedia, nd)

Thyroid stimulating hormone (TSH)

TSH stimulate the thyroid gland to make the Triiodothyronine (T3) and Thyroxine (T4) to control body metabolism.(Dr.Joshua Bederson,nd)

TSH playing a role in converting the food to use as energy in human body.(Jennifer A.Philips, 2001)

TSH also are responsible for regulating our body temperature. (Jennifer A.Philips, 2001)

Luitenizing hormone (LH)

Stimulation of the ovulation and also corpus luteum development are produced from this hormone. Other than that it is also responsible for stimulation of the Leydig Cell production of testosterone in men. (Rajin Singha,2011)

Follicle Stimulating Hormone (FSH)

According to Mayo clinic,2011, FSH that released from the anterior lobe of pituitary gland are responsible for stimulating growth of the ovarian follicle including the pubertal maturation and also reproductive process of the body. When the follicle getting bigger or develop the estrogen hormones will be increased and automatically transfer to the bloodstream. Then the function of the estrogen is to thicken the endometrium before the ovulation occurs.

Adrenocorticotropic hormone (ACTH)

This hormone stimulating the adrenal cortex to stimulate the formation of steroid hormones in the adrenal gland like cortisol hormone which is responsible to control homeostasis such as blood sugar level,immune response,central nervous system activation, blood pressure, and also anti-inflammatory actions.( University of California San Franscisco UCSF,2012) , (Dr. james L .wilson, 2011)

Posterior lobe of the pituitary gland that called neurohypophysis and known to secreted two types of hormones:

Oxytocin hormone (OT)

OT hormone function is for uterine contractions which is use after distension of the cervix of vagina during labor. Other than that this hormone are responsible for lactation acting to Stimulating the nipples to produce milk for breast feeding that very important for the new born. (Rajib Singha, 2011)

Antidiuretic hormone (ADH)

Another name is vasopressin that is important for regulating water balance in human body which will increase the absorption of water into the blood by kidneys. In addition, this hormone also effect the vascular spasm by causing the widespread constriction of arterioles that result in increased arterial pressure. The raises blood pressure in arterioles affected by the high concentrations of ADH. (R.Bowen, 2006) , (Wikipedia, nd)

Intermediate lobe is the lobe that being a boundary between the posterior lobe and also the anterior lobe. Other names of this lobes is pars intermedia. This lobe are responsible only for the melanocyte formation or melanocyte stimulating hormone which is skin cells that contain the black pigment. Unfortunately, pars intermedia is exist only during the fetal development that is recognized in earliest stage of adulthood. After that the posterior lobe and the anterior lobe will responsible for every hormone that secreted from the connection between hypothalamus and the pituitary gland. (Rajib Singha, 2011)

The third lobe is posterior lobe that also known as neurohypophysis. Compared to the anterior lobe, this lobe only responsible to secretes two type of hormones, which is antidiuretic hormone (ADH) and oxytocin. (Rajib Singha, 2011) Oxytocin hormone functions are for stimulation of the nipples for breast feeding and also important for distension of the cervix or allow the muscle of the uterus to contract and help the baby out during labor. (Rajib Singha, 2011) ADH hormone, responsible for decreasing amount of urine that excreted and at the same time will work to increase the absorption of water into the blood by the kidneys. (Rajib Singha, 2011)

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Introduction of Pituitary adenoma

Pituitary adenoma is a tumour that grows from the pituitary gland and the tumour is called an adenoma which is a benign tumour. Mostly this tumour arises or grows from the anterior lobe of the pituitary gland and disturbs its normal function. The larger the tumour growth at the lobe the more its change the production of the hormones. (Mayoclinic,2011) Pituitary tumour can be divided into two categories, which is functional tumours and non-functional tumours. Functional tumours, is a tumour that interfere with the normal hormone regulation process and also secrete abnormal amount of hormones. If the tumour disturbing the prolactin hormone secretions, then we called it prolactinoma. The second category which is non-functional tumours do not secreting hormones. But, the tumour getting bigger and larger that will causing vision loss because the tumour suppress the optic nerves. Besides that, it is also can give us headache, nausea, vomiting or more serious will fatigue. (Mayfield clinic, 2009)


Causes of pituitary adenoma

The causes of uncontrolled cell in the pituitary gland are still unidentified and remain unknown. (Krisha,2012) Research that was done until now, only showing that these disease are not inherited for common pituitary adenomas. However, there are cases that known as familial pituitary tumours which is high probability in getting pituitary adenoma. Even though some research said that these disease may be inherited, but it is rare happen. The common pathology from the familial pituitary tumours types are gigantism and acromegaly. (UCLA, 2012)




Primary malignant tumours are the tumour that hard to get. It is occur by steps and then continued to irreversible phase and become a tumour.The tumour present is not automatically become a tumour, but then from step by step. (Medscape,2011) So that, there are two theories known for pathophysiology of pituitary adenoma. The first theory is the tumour produce because of any abnormalities that occur within the gland itself. The second theory it is due to the unregularly hormone secretions. However, research more agreed with the first theories, which is occur because the abnormalities within the gland itself. These tumours develop from a single mutation and turn to clonal expansion. (Alexander et al.1990) Pituitary tumour or adenoma mostly are benign tumour that develop from adenohypophyseal from the pituitary gland. Because of the abnormal secretion and expression of the pituitary hormones , that may lead to the endocrinalagical syndrome. For instance, hyperprolactinoma, acromegaly, cushing disease's and sometimes hypophytuitarism. Alternatively, they may be functionally silent and initially diagnosed as an expanding sellar mass resulting in hypopituitarism, usually with central hypogonadism, (Shimon; Melmed, 1997) There are some of pituitary tumours produced from a clinical syndrome which is in multiple endocrine neoplasia type 1 (MEN 1),an autosomal genetic disorder, and prolactinoma that is occur with parathyroid and pancreatic islet cells. (Medscape,2011)

Figure 1.

Image from (Shimon; Melmed, 1997)

Sign and Symptoms of pituitary adenoma

The symptoms of pituitary adenoma are divided to two categories, whether the tumours are functional tumour (hormone producing) or non-functional tumour (clinically non-functioning). (UCLA, 2012)

Functional tumours occur when there are abnormal secretions of the hormone whether excessive or low that will disturbing the normal function of the hormone process. According to Mayfield clinic, 2009, state that the tumour is named according to the part or origin of the tumour produce. For instance, prolactinoma disease is coming from abnormal secretions of prolactin hormones.

However non-functional tumours affect the normal process by the size of the tumour. The bigger the tumours the more its compress or suppress the others organ near it. Larger tumour can give a big problem to the eyes by pressing the optic nerves and can lead to vision loss or in simple word blind. (UCLA, 2012)

The functional tumour

Prolactin-producing tumours.

This is the most common type of pituitary tumour known as prolactinoma. Prolactinoma occur because of excessive production of prolactin hormone. In women it may cause menstruation process to stop or irregular periods time occur, and at the same time lead to loss of milk production for breast feeding purposes. Because of this disease too, they may loss of libido or loss interest in sex. (, nd) Very high production of prolactin hormone in men may cause enlarged breast and erectile dysfunction. If this hormone production continuously secreted in abnormal level, they will face infertility problems. Same with women, men also having low sex drive, this is one of the symptoms having a prolactinoma disease. (Mayfield clinic, 2012)

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Growth hormone-producing tumours.

According to Mayfield clinic, 2012 this disease most occurs in men, however, Memorial Sloan Kettering cancer centre, nd state that men and women getting this disease are equally same. This tumour may cause two type of disease which is acromegaly and gigantism. Gigantism caused by overproduction of growth hormone in children and adolescent. The symptoms shown are very rapid grow with very tall that exceed the 7 feet's measurements. Due to rapid growth its cause joint pain. Excessive production of the growth hormone eventually stimulates the secretion of other hormones which is insulin-like growth-factor. This hormone responsible for all the changes that occur in human body. Acromegaly much more affect adult by showing obviously the enlargement of hands and feet. Others, such as protruding jaw, coarsened facial features, enlargement of heart muscle that called cardiomyopathy and also skin thickened. (Wolters Kluwer,2012)

Adrenocorticotrophic hormone secreting (ACTH) Tumours.

Presence of ACTH tumour causing the symptoms of Cushing disease. Cushing disease occur due to excessive production of adrenal glucorticortoids by taking this hormone from asthma, rheumathoid arthritis, lupus or inflammatory diseases medication which is prednisone. (Intelihealth,nd) The symptoms showing that cushing disease presence are obesity, easy bruising, thin skin, appearances of stretch mark (purplish, pinkish) on the abdomen, thigh, and also at the buttock. Others, acne, over hair producing in women, muscle weakness and menstrual disorders.(eMedTV,2008)

The Non-functional tumour symptoms:

Depending to the size of the tumour, large tumour(larger than 10 mm) or called macroadenona may cause hypopituitarism whether it is partial or complete failure. For the small tumour (less than 10 mm) are called microadenoma. However every symptoms that appear are depends on type of hormone involved. Low luitenizing hormone(LH) and follicle stimulating hormone (FSH) may causing low sexual drive, low testerone level and also impotence.But for women its more to infertility. The others common symptoms can lead to loss of peripheral vision or called as bitemporal hemianopsia. (UCLA,nd) When the tumours interfere with the secretion of hormones and grows beyond the sella turcica, it may cause fatigue, loss of body hair and also pale skin. Severe effect cause partial paralysis of the eye muscle.(Mayfield clinic,2009)


There are 3 imaging modalities that can be used to confirm pituitary adenoma which is the plain skull radiograph, Computed tomography (CT) Scan, and the last one is Magnetic resonance imaging (MRI). Every type of these modalities provides their own advantages when it's come to delineating the tumour.

Comparison of modalities used

Plain Skull radiograph:

Plain skull radiograph is excellence to show the abnormalities of the bone at the skull part. However to delineating the soft tissue isn't the best if only use plain skull x-ray. (Chaudary: Bano, 2011) Using the sella region to diagnose the pathology by using plain skull x-ray is not the good way because of the variations of size, cortical margins of sella and also the shape. The variations of sella shape are not showing that there are pathologies existed because of natural shape of sella itself. So that, the plain radiograph only showing minimal information that non-invasive and cheaper than CT and MRI. (Medtextfree,2011)

Ct Scan:

CT is the second modalities that used in detecting pituitary gland. Compared to the plain radiograph and MRI, it is more sensitive in case of imaging the calcifications within the soft tissue. However, to perform that, optimal soft tissue intravenous contrast agent is very crucial and important in enhancing the vasculature. (Medtextfree,2011) Even though CT is the best when imaging the calcifications, but it is serving the patients with high ionizing radiation compared to plain radiograph and MRI an only used to rule out the tumour whenever the MRI is contraindicated to the patients that having pacemaker or metallic implants in their body. Another disadvantage is when less optimal soft tissue contrast given, it won't be enough to show the pituitary lesion and other pathology within the soft tissue. (Chaudary: Bano, 2011)

Advantages of MRI

The best modalities for imaging the pituitary adenoma:

The most imaging modalities that have been used to show the pituitary lesion are magnetic resonance imaging (MRI). MRI is the most preferred modality because of having so many advantages that despite the disadvantages. Even though the procedure of MRI take a long time than CT, but then it isn't provide any ionizing radiation that may give high dose to the patients and direct multiplanar scanning. The most benefits from MRI are because of the ability to show the superior soft tissue, accurate imaging the pituitary gland, infundibulum, chiasm, cavernous sinuses, and neighbouring vascular structures. In addition it is also help in differentiating between the fats, haemorrhage and cystic areas from tumour tissue. (Department of Health Western Australia,2007)


MRI are frequently used and accurately for evaluating the internal structures of the brain and also provides very detailed information about the human brain tumour anatomy, vascular structure and also the vascular supply. Imaging the pituitary in MRI also called as sella MRI. Brain matters which is the grey and the white matter are easily to seen and evaluate in MRI. The most strength of MRI than CT scan and the others are, by using the sequences in MRI, it is providing the best image with the accurate position and sizes.(Sohal,2010) For instance, using the coronal planes, may show the single view of the midline structures of brain. Even though the pituitary gland is very small, but when using high spatial resolution the gland easily to seen and evaluated. By using the T1 weighted sequences with and without the gadolinium is the good optimal sequence to evaluating the underlying pathology and the anatomy of the brain with help from the contrast enhancement. (Sohal,2010) The T1 weighted show the fat tissue appearance as bright with high intensity (hyperintense), and the water as dark with low signal intensity (hypointense). (Tonarelli,nd) For the T2 weighted, it is show the high fat tissue content as dark with areas of low signal intensity (hypointense) and the high water contents as bright with high signal intensity (hyperintense) that is best to show the pathology. (Tonarelli,nd) This is proven that MRI is the best than Ct in imaging the brain pathology and anatomy.


Diagnostic Accuracy

Image features of disease causes by the pituitary adenoma

Normal Image of pituitary gland without any pituitary disease.

The image from( Endotext) Chapter 4 - Radiology of the Pituitary

Figure 1A Sagittal T1 weighted unenhanced images of the pituitary fossa demonstrate normal anatomy. The anterior pituitary tissue, A, is visible within the sella and the posterior pituitary bright spot, P, is evident behind it. The stalk (arrow) is well seen with a small cleft of CSF visible within it superiorly -the infundibular recess of the third ventricle. The optic chiasm, C, and mamillary bodies, M, are seen in the suprasellar region. B-Brainstem, S-sphenoid air sinus, CL - clivus.(Evanson,2009)

The image from( Endotext) Chapter 4 - Radiology of the Pituitary

Figure 1B Coronal T1 weighted unenhanced images of the pituitary fossa. The anterior pituitary gland, A,is within the fossa. The posterior pituitary bright spot is visible centrally, P. The stalk is seen extending up into the suprasellar region. The optic chiasm, C, is visible. The cavernous segments of the carotids arteries, I , are seen within the cavernous sinuses, which form the lateral boundaries of the pituitary fossa. (Evanson,2009)


a)pituitary macroadenoma pre-op

b)pituitary macroadenoma post-op

Pre operation image of pituitary macroadenoma

Post operation of pituitary macroadenoma

The image of macroadenoma from (Hopkins Medicine) Neurology and Neurosurgery


Figure (a) a tumour can be seen in the sella region that more than 10 mm in size automatically prove the macroadenoma present. Figure (b) shows the post operation of the macroadenoma. The sella region space can be seen very clearly without any abnormalities present. (Hopkins,nd)

Radiographic features

Pituitary macroadenomas are by definition > 10mm mass arising from the pituitary gland, and usually extending superiorly. Indentation at the diaphragma sellae can give a snowman or figure eight configuration. (Dr Yuranga Weerakkody et al,nd)


The Image from (


Figure (A) A coronal T1 weighted MRI with contrast in apatient with a sellar GH secreting adenoma. The arrows above showing the common findings of "cutis gyrate".(,nd)

Figure (B) A sagittal T1 weighted MRI using the same patient. The arrows show the frontal bossing within the enlarged frontal sinus. (,nd)


The Image of MRI prolactinoma patients (Neurology and neurosurgery,2010)


MRI of a 58 years old patient with an invasive, cystic giant prolactinoma, which has destroyed the base of the scull, caused blindness, and infiltrated the lateral ventricle. He did not respond to DA-agonists and died because of the local tumor complications, though he had no distant metastases, in the CNS or elsewhere. (Clayton, 2010)