Session 8 Flashcards
(162 cards)
1
Q
Where is the pituitary gland located?
A
Beneath the hypothalamus in a socket of bone called the sell turcica
2
Q
What is the name given to the socket of bone where the pituitary gland sits?
A
Sella turcica
3
Q
Where is the pituitary gland located in relation to the hypothalamus?
A
Below the hypothalamus
4
Q
The hypothalamus and pituitary gland form a functional unit that serves as a link between…
A
The endocrine and nervous systems
5
Q
The pituitary gland consists of how many parts? Name them
A
2 parts
Anterior pituitary gland
Posterior pituitary gland
6
Q
Describe the embryological origins of the…
I) anterior pituitary
II) posterior pituitary
A
Arises from evagination of oral ectoderm
Arises from neuroectoderm
7
Q
What is oral ectoderm?
A
Primitive gut tissue (ap arises from this)
8
Q
What is neuroectoderm?
A
Primitive brain tissue (pp arises from this)
9
Q
Which parts of the pituitary gland are physically connected to the hypothalamus?
A
Posterior Pituitary Gland
10
Q
The hypothalamus drops down through the ________________ to form the posterior pituitary
A
Infundibulum
11
Q
What is the colloquial name for the infundibulum?
A
Pituitary stalk
12
Q
Where is oxytoxin and ADH produced?
A
By neurosecretory cells in the supraoptic and paraventricular nuclei of the hypothalamus
13
Q
Oxytocin and ADH are produced by neurosecretory cells of which parts of the hypothalamus?
A
Supraoptic and paraventricular nuclei
14
Q
Oxytocin and ADH produced in the supraoptic/paraventricular nuclei of the hypothalamus are transported down nerve cell axons to the…
A
Posterior pituitary
15
Q
How is oxytocin/ADH transported from the hypothalamus to the posterior pituitary?
A
Down nerve cell axons
16
Q
Where is oxytocin and ADH…
I) produced
II) stored
III) released into the general circulation
A
Hypothalamus - supraoptic/paraventricular nuclei
Posterior pituitary
Posterior pituitary
17
Q
The ADH and oxytocin released form the posterior pituitary act on…
A
Distant targets
18
Q
Hormones synthesised in hypothalamus are transported down axons and stored in the…
…before being released into the hypophyseal portal system
A
Median eminence
19
Q
Hormones for stimulation of the anterior pituitary are synthesised in the ______________, stored in the ___________ __________ and then released into the…
A
Hypothalamus
Median eminence
Hypophyseal portal system
20
Q
What is the function of the hormones released from the hypothalamus for action on the anterior pituitary?
What name is given to this type of cell/hormonal communication?
A
They stimulate/inhibit target endocrine cells in the anterior pituitary
Neurocrine function
21
Q
Describe the endocrine function of the anterior pituitary
A
Endocrine cells in the anterior pituitary secrete a variety of hormones into the bloodstream that act on distant sites
22
Q
Does the anterior pituitary have autocrine/paracrine functions?
A
Yes - hormones released from the anterior pituitary effect neighbouring cells
23
Q
Hormones are produced by __________ cells in the hypothalamus
A
Nerve
24
Q
Hormones secreted exclusively into the hypophyseal portal system affect _____________ cells within the _____________ ___________
A
Endocrine
Anterior pituitary
25
Which hormones are produced in the hypothalamus for release from the posterior pituitary?
Oxytocin
| ADH
26
What is the function of oxytocin? Where is it released?
Milk let down and uterus contractions during birth
Posterior pituitary
27
What is the function of ADH? Where is it released?
Regulation of body water volume
Posterior pituitary
28
The tropic hormones of the hypothalamus have direct effects on the release of other anterior pituitary hormones. What is meant by the term tropic?
Affects the release of other hormones in the target tissue (anterior pituitary)
29
How many tropic hormones are produced in the hypothalamus for effect on the anterior pituitary?
6
30
Name the 6 tropic hormones produced in the hypothalamus for effect on the anterior pituitary
```
TRH - thyrotropin releasing hormone
PIH - prolactin release-inhibiting hormone
CRH - corticotropin releasing hormone
GnRH - gonadotropin releasing hormone
GHRH - growth hormone releasing hormone
GHIH - growth hormone inhibiting hormone
```
31
Somatostatin is also known as...
Growth hormone inhibiting hormone
32
Dopamine is also known as...
Prolactin release-inhibiting hormone
33
Which 6 hormones are released from the anterior pituitary?
```
TSH - thyroid stimulating hormone
FSH - follicle stimulating hormone
GH - growth hormone
ACTH - adrenocorticotropic hormone
PL - prolactin
LSH - luteinising hormone
```
34
What is the function of TSH?
Secretion of thyroid hormone from thyroid gland
35
What is the function of adrenocorticotropic hormone (ACTH)?
Secretion of hormones from adrenal cortex (cortisol)
36
What is the function of luteinising hormone?
Ovulation and secretion of sex hormones
37
What is the function of follicle stimulating hormone?
Development of eggs and sperm
38
What is the function of prolactin?
Mammary gland development and milk secretion
39
What is the function of growth hormone?
Growth and energy metabolism
40
Growth hormone stimulates...
IGFs
| Insulin-like Growth Factors
41
TRH released from the hypothalamus activates which hormone in the anterior pituitary?
What does this hormone released from the anterior pituitary act on?
TSH
Thyroid gland
42
Which hormone from the hypothalamus results in the release of ACTH from the anterior pituitary?
ACTH released from the anterior pituitary acts on...
CRH
Adrenal cortex
43
Which hormones affect the release of prolactin from the anterior pituitary? What effect does each have?
Prolactin acts on which gland?
PIH (inhibit)
TRH (stimulatory)
Mammary gland
44
What hormones in the anterior pituitary does GnRH act on?
What parts of the body do these hormones released from the anterior pituitary act on?
LH
| FSH
45
The pathways by which hypothalamic and anterior pituitary hormones are produced is often regulated by...
Negative feedback
46
What is apoptosis?
Programmed cell death - cell death by shrinkage
47
What is necrosis?
Cell death by damage
48
What is atrophy?
Decrease in cell number/size
49
What is hyperplasia?
Increase in cell number
50
What is hypertrophy?
Increase in cell size
51
What is the most important endocrine regulator of postnatal growth?
Growth hormone
52
State 4 factors that influence growth...
Genetics
Environment
Nutrition
Hormones
53
Where is growth hormone produced?
In the anterior pituitary
54
What hormone stimulates the release of growth hormone?
What hormone inhibits the release of growth hormone?
GHRH
GHIH
55
What type of hormone is growth hormone?
PEPTIDE HORMONE - protein hormone consisting of a single peptide
56
The growth-promoting effects of growth hormone are mainly excreted indirectly via...
Insulin-like growth factors
57
In response to growth hormone, cells of the liver and skeletal muscle produce/secrete...
Insulin-like growth factors
58
What role does growth hormone and the IGFs they act via have during childhood and teenage years?
It is essential for NORMAL growth
GH ---> Long bone development
IGFs ---> Bone + Cartilage growth
59
What role does GH and IGFs play in adults?
Helps maintain muscle/bone mass and promotes healing and tissue repair
60
What role does GH specifically have in children?
Involved in long bone development
61
What role do IGFs as a result of GH specifically have in children?
Involved in both bone + cartilage growth
62
Control of GH secretion is principally via the...
Hypothalamus and secretion of GHRH/GHIH
63
What role does the CNS play in the control of GH secretion?
Regulates GH secretion via inputs into the hypothalamus affecting GHRH/GHIH levels
64
Name two things that can result in increased GH secretion?
Onset of deep sleep
Stress
Exercise
Fasting
65
Name two things that can result in a decrease in GH secretion
Obesity
| R.E.M. Sleep
66
GH secretion is regulated by long loop and short loop negative feedback.
What is long loop negative feedback mediated by?
What is short loop negative feedback mediated by?
IGFs
GH
67
Name 3 effects that IGF has on the control of GF release
Negative feedback via long loop
Inhibits release of GHRH
Stimulates release of GHIH
Inhibits release of GH from anterior pituitary
68
The short loop in the negative feedback control of GH secretion is mediated by ____ itself via stimulation of ______ release
GH
GHIH
69
What can growth hormone deficiency result in?
Pituitary dwarfism in childhood
70
What is the usual treatment for growth hormone deficiency?
GH therapy
71
What are three signs of growth hormone deficiency?
Height below 3rd percentile on standard growth charts
Growth rate slower than expected for age
Delayed or no sexual development during teen years
72
Growth hormone in excess in adults results in...
Acromegaly
73
Growth hormone in excess in children results in...
Gigantism
74
Growth hormone in excess in children (leading to gigantism) is commonly caused by...
Pituitary adenoma
75
What does acromegaly mean?
Large extremities - e.g. Hands, feet, lower jaw etc.
76
What IGFs are found in mammals?
IGF2
| IGF1
77
IGF2 is mainly involved in...
Fetal growth
78
What is the major growth factor in adults?
IGF1
79
What modulates the availability of IGFs?
Binding proteins
80
By which mechanism do IGFs act?
Autocrine
Paracrine
Endocrine
81
IGF acts on which receptors?
IGF receptors
82
IGF binds to IGF receptors modulating... (4)
Hyperplasia
Hypertrophy
Increase rate of protein synthesis
Increase rate of lipolysis in adipose
83
How does GH exert its effect on cells?
Bind to GH receptors which activate Janus kinases (JAKs), resulting in transcription factor activation and IGF production
84
Binding of GH to GH receptors results in...
Activation of Janus kinases (JAKs), transcription factor activation and IGF production
85
Apart from growth hormone, state three other hormones that can influence growth?
Insulin
Thyroid hormones
Androgens
Glucocorticoids (cortisol)
86
Are pituitary tumours benign or malignant?
Benign
87
Name two ways a pituitary tumour may present...
Due to...
Mass effect of tumour on local structures
Abnormality in pituitary function
88
Benign pituitary tumours can present due to the mass effect of the tumour on local structures. State two symptoms that may result from this
Headache
| Visual loss
89
Benign pituitary tumours can present due to abnormalities in pituitary function. What sorts of symptoms may be seen?
Symptoms of hypo- or hypersecretion of the pituitary gland
90
Which hormones of the anterior pituitary gland are under 'positive control'?
Which hormones of the anterior pituitary gland are under 'negative' control?
```
GH (small inhibitory effect by GHIH)
ACTH
LH
FSH
TSH
```
Prolactin
91
What effect will a tumour blocking the passage of hormones from the hypothalamus have on the levels of the hormones in the anterior pituitary?
Reduction in the 'positive control' hormones (GH, TSH, ACTH, FSH, LH)
Increase in the 'negative control' hormone (prolactin)
HYPOPITUITARISM
92
In a tumour affecting the pituitary gland, state the order in which the 'positive control' hormones are lost...
GH
LH & FSH
TSH & ACTH
93
What effect can growth hormone deficiency seen in a tumour affecting the pituitary gland result in, in adults and children?
Short stature in children (pituitary dwarfism)
| Reduced quality of life in adults
94
What effect can gonadotropin deficiency (LH & FSH) seen in a tumour affecting the pituitary gland result in, in adults and children?
Delayed puberty in children
Loss of secondary sexual characteristics in adults
Loss of periods in women
95
What effect can TSH deficiency as a result of a tumour affecting the pituitary gland result in?
Low thyroid hormone - weight gain, tiredness, slow pulse
96
What effect can ACTH deficiency as a result of a tumour affecting the pituitary gland result in?
Low cortisol - tiredness, dizziness, low BP and low sodium
97
Small tumours in the pituitary gland can result in overactivity in parts of the pituitary gland and excess of hormones being produced.
What hormones are most commonly seen in increased levels in these cases?
Prolactin
GH
ACTH
98
A stimulation test is used for suspected...
Hormone deficiency
99
A suppression test is used for suspected...
Hormone excess
100
How is ACTH deficiency tested for? (2)
Direct stimulation of adrenals by ACTH
| Insulin stress test (hypoglycaemia)
101
How is ACTH excess tested for?
Suppress ACTH with steroids
102
How is GH deficiency tested for?
Insulin stress test (hypoglycaemia)
103
How is GH excess tested for?
Suppress GH with glucose load
104
What is tested for in the blood to check for pituitary disease of the thyroid axis?
Free T4
| TSH
105
What is tested for in the blood to test for pituitary disease of the gonadal axis?
LH
FSH
Men - testosterone
Women - oestradiol
106
What is tested for in the blood to test for pituitary disease of the prolactin axis?
Serum prolactin
107
What is tested for in the blood to test for pituitary disease of the HPA axis?
0900 cortisol levels
108
What is tested for in the blood to test for pituitary disease of the GH axis?
GH
| IGF1
109
What is a prolactinoma?
Benign prolactin secreting pituitary tumour
110
What is described as a 'macro-adenoma' with regards to a prolactinoma?
> 1 cm in size
111
What is described as a 'micro-adenoma' with regards to a prolactinoma?
< 1 cm in size
112
The larger the size of a prolactinoma, the higher the...
Prolactin
113
What is the treatment for a prolactinoma?
Treatment with tablets - dopamine agonist
114
Does the treatment for a prolactinoma change depending on the size of the tumour?
No - doesn't change.
Dopamine agonist tablets for treatment
115
What tablets are used for the treatment of a prolactinoma?
Dopamine agonist tablets
116
Is surgery required for the treatment of a prolactinoma?
No - tablets are the treatment for this
117
It is important to check prolactin levels before contemplating surgery for a pituitary tumour as treatment is with tablets.
What is the normal range for serum prolactin?
50-400
118
State three symptoms of hyperprolactinaemia in women
Menstrual disturbance
Fertility problems
Galactorrhoea
119
Hyperprolactinaemia can cause fertility problems as prolactin directly inhibits...
Luteinising hormone
120
What is galactorrhoea?
Milky discharge in the nipples outside pregnancy
121
Are larger prolactinoma usually seen in men or women?
Men
122
The symptoms of hyperprolactinaemia in men are associated with the symptoms of...
Low testosterone (due to prolactin inhibition of LH)
123
The symptoms of low testosterone are often...
Non-specific
124
Give an example of mass symptom that may be seen in a male with hyperprolactinaemia
Visual loss
125
Do symptoms of hyperprolactinaemia present later in men or women? Why?
Present later in men
No periods in males
126
When will a high prolactin level be treated with surgery?
When levels are below 5000 (with a pituitary mass on MRI)
127
Why is a pituitary mass on MRI with prolactin BELOW 5000 treated by surgery?
High prolactin is due to disinhibition of prolactin by blocking of the pituitary stalk rather than active secretion of prolactin
128
When will a high prolactin level be treated with medication?
When prolactin levels are ABOVE 5000
High prolactin is due to active prolactin secretion (prolactinoma)
129
What happens in a non-functioning pituitary adenoma?
There is no secretion of biologically active hormones
130
The clinical features of a non-functioning pituitary adenoma are either as a result of...
Mass effect OR low pituitary hormones
131
Dopamine agonists used in the treatment of a prolactinoma stimulate which receptors?
D2 receptors
132
Give an example of a dopamine agonist used in the treatment of prolactinoma
Bromocriptine
133
Dopamine antagonists can cause high...
Prolactin
134
What sorts of medications are dopamine antagonists?
Anti-sickness
| Anti-psychotics
135
What does acromegaly mean? How does it often present?
Large extremities
Large hands and feet
136
What causes acromegaly?
Excess GH - GH secreting pituitary tumour
137
What causes the excess GH that causes acromegaly?
GH-secreting pituitary tumour
138
State 5 long-term complications of untreated acromegaly
```
Premature cardiovascular disease
Increased risk of colonic tumours
Increased risk of thyroid cancers
Disfiguring body changes
Hypertension
Diabetes
```
139
State three biological tests that can be used to confirm the diagnosis of acromegaly
Oral glucose tolerance test (glucose load) - failure to suppress GH ---> acromegaly
Elevated IGF1
Elevated mean GH levels
140
What is the treatment for acromegaly?
Surgical removal of the tumour
141
If a more complicated GH-secreting pituitary tumour is causing acromegaly what other treatments may be required in addition to surgery?
Dopamine agonist
Somatostatin analogues
Pegvisomant
Radiotherapy
142
How do dopamine agonists and somatostatin analogues work as an additional treatment for acromegaly?
Reduced GH secretion
143
Describe two methods of radiotherapy that may be carried out as an additional treatment for acromegaly
External beam
Gamma knife
144
Compare external beam and gamma knife radiotherapy
External beam - multiple short bursts over several weeks
Gamma knife - high concentration over single time
145
Too much ACTH for example due to an ACTH-secreting tumour can lead to ______________ disease
Cushing's
146
Cushing's disease is caused by too much cortisol due to too much ______ being released from the pituitary gland
ACTH
147
Compare Cushing's disease and Cushing's syndrome
Cushing's disease is caused by a pituitary tumour
Cushing's syndrome is caused by something else
148
Give an example of something the may cause Cushing's SYDROME
Adrenal tumour
149
Describe the classical change in appearance that is seen in Cushing's disease
```
Round pink face with round abdomen
Skinny and weak arms/legs
Thin skin and easy bruising
Red stretch marks (striae) on abdomen
High blood pressure
Diabetes
Osteoporosis
```
150
What is diabetes insipidus?
Production of large quantities of pale (insipid) urine. Extreme thirst due to fluid loss.
151
Which gland secretes ADH?
Posterior pituitary
152
Normally ADH is secreted from the ______________ __________ resulting in decreased urine. ADH binds to ADH receptors on the _______________ membrane of kidney cells and opens __________________ resulting in ______________ reabsorption of water from urine
Posterior pituitary
Basolateral
Aquaporins
Increased
153
What causes diabetes insipidus?
Not enough ADH is secreted from the posterior pituitary ---> not enough water reabsorbed ---> large quantities of pale urine produced
154
Name two types of diabetes insipidus
Cranial DI
Nephrogenic DI
155
Compare cranial and nephrogenic diabetes insipidus
Cranial DI - ADH deficiency
Nephrogenic DI - ADH resistance
156
What usually causes nephrogenic diabetes insipidus?
Kidney disease ---> resistance to ADH
157
State three consequences of untreated diabetes insipidus
Severe dehydration
Very high sodium levels (hypernatraemia)
Coma ---> Death
158
What is the usual treatment for diabetes insipidus?
Synthetic ADH
159
What is pituitary apoplexy?
Sudden vascular event in a pituitary tumour - either a haemorrhage or infarction
160
The 'sudden vascular event' seen in pituitary apoplexy is either...
Haemorrhage or infarction
161
Describe the typical clinical presentation of pituitary apoplexy (5)
```
Sudden onset headache
Double vision
Visual field loss
Cranial nerve palsy
Hypopituitarism
```
162
What is the most dangerous consequence of hypopituitarism?
Cortisol deficiency
