Physio Cobine- The pituitary and hypothalamus Flashcards
(165 cards)
1
Q
Where is the hypothalamus located?
A
located inferior to the thalamus (i.e hypo-thalamus)
2
Q
How big is the pituitary and where is it located?
A
it is 1 cm and located in the sella turcica (side of head behind eyes kind of
3
Q
How is the hypothalamus connected to the pituitary?
A
pituitary stalk (aka the infundibulum or hypophysial stalk)
4
Q
What plays a role in connecting the nervous system to the endocrine system and regulates the pituitary gland?
A
the hypothalamus
5
Q
What does gonadotropin releasing hormone (GnRH) stimulate?
A
FSH and LH
6
Q
What does growth hormone releasing hormone stimulate?
A
growth hormone
7
Q
What inhibits growth hormone?
A
somatostatin
8
Q
What does thyrotropin releasing hormone (TRH) do?
A
TSH (thyroid stimulating hormone)
9
Q
What does dopamine (DA) do?
A
inhibits prolactin
10
Q
What does CRH (corticotropin releasing hormone) do?
A
releases ACTH (adrenocortropic hormone)
11
Q
What all does the hypothalamus secrete?
A
DA, GnRH, GHRH, CRH, TRH, SS,
Danielle Great Grandfather Captained The SS
12
Q
The pituitary gland is comprised of what 2 lobes.
A
the anterior lobe AKA adenohypophysis
the posterior lobe AKA nerohypophysis
13
Q
What separates the two lobes of the pituitary gland and what blood vessels flow through this?
A
the Pars Intermedia
None, it is avascular
14
Q
In the adenohypophysis (anterior lobe) of the pituitary gland, what do we find?
A
hormone-producing adenoid (glandular cells)
15
Q
In the neurohypophysis (posterior lobe) of the pituitary gland, what do we find?
A
axon terminal of neurosecretory cells originating in the hypothalamus
16
Q
Explain the embryonic development of the pituitary gland
A
Anterior lobe comes from pharyngeal epithelium (rathke’s pouch)
Posterior lobe comes from neural tissue outgrowth from hypothalamus
17
Q
What does the posterior pituitary gland function in?
A
ADH and oxytocin release
made in hypo, secreted by posterior pituit.
18
Q
What does the anterior pituitary gland function in?
A
prolactin LH FSH AdrenoCorticotropin growth Hormone TSH
19
Q
Secretion of the anterior pituitary is contolled by hormones secreted by neurons within the (blank)
A
hypothalamus
20
Q
Secretion from the posterior pituitary is from (blank) which originate in the hypothalamus and terminate in the posterior lobe.
A
magnocellular neurons
21
Q
What artery supplies the anterior lobe?
What artery supplies the posterior lobe?
A
superior hypophyseal artery
inferior hypophyseal artery
22
Q
Which lobe of the pituitary is darker purple
Why?
A
the anterior lobe
There are a bunch of basophil cells that make it look dark
23
Q
What are the acidophil cells of the anterior pituitary?
A
Somatotropes -> makes GH
Lactotropes-> makes prolactin
24
Q
what do somatotropes of the anterior pituitary gland make?
A
growth horomone (GH)
25
What do lactotropes of the anterior pituitary gland make?
prolactin (PRL)
26
What are the basophilic cells of the anterior pituitary gland?
Corticotropes
thyrotropes
gonadotropes
27
What do corticotropes secrete?
adrenocorticotropic hormone (ACTH)
28
What do thyrotropes secrete?
Thyroid-stimulating homrone (TSH)
29
What do gonadotropes secrete?
FSH and LH
30
What are the three hormone types?
peptide and protein hormones
tyrosine-derived hormones
steroid hormones
31
What are these:
| e.g. ACTH, ADH, oxytocin, etc.
peptide and protein hormones
32
What are these:
| thyroid hormones and catecholamine hormones
tyrosine-derived hormones
33
What are these:
| Glucocorticoids, mineralocorticoids, sex hormones.
Steroid hormones
34
What are the majority of hormones and how are these synthesized?
peptide and protein hormones
| synthesized as preprohormones
35
What do peptide and protein hormones need and what is their half-life?
need post-translational processing
| 4-170 minutes
36
Explain protein hormone synthesis
mRNA -> preprohormone-> signal sequence directs preprohormone into ER-> enzymes snip off signal sequence-> prohormone (inactive)->golgi->secretory vesicles w/ prohormone and enzymes-> active peptides-> exocytosis-> hormones in circulation
37
(blank) of amino acids alters the function and structure of proteins. This occurs in the ER, Golgi and secretory vesicles.
Post-translational modification
38
What are these:
cleavage
attachment of biochem groups (acetate, phosphates)
changing chemical nature of AA (citrullination)
Change structure (disulfide bridges)
Folding
post-translational processing
39
```
Cells and hormones of anterior pituitary glands:
Somatotropes-GH
lactotropes-Prolactin
corticotropes-ACTH
thyrotropes-TSH
gonadotropes-FSH and LH
These are all (blank) hormones.
```
peptide and protein hormones
40
What are the three anterior pituitary hormone families?
1) glycoprotein family
2) growth hormone/prolactin family
3) Pro-opiomelanocortin
41
What does pro-opiomelanocortin effect?
adipose tissue, and the adrenal gland
42
```
What are these:
TSH
LH
FSH
HCG
Alpha-fetoprotein
Erythropoietin (EPO)
```
hormones that are glycoproteins
43
(blank) are proteins that are comprised of alpha and beta subunits and a carb chain.
glycoproteins
44
The alpha unit of a glycoprotein is (blank) while the beta subunit is (blank)
common
| unique
45
How is the carbohydrate attached to the protein in glycoproteins?
glycosylation
46
What does glycosylation determine?
the hormone half-life
47
What does TSH do?
it makes the thyroid gland to increase synthesis and secretion of thyroid hormones
48
What does FSH do?
in the ovary it increases folliculogenesis and estrogen synthesis
in the testis it increases sperm maturation
49
What does LH do in the ovary follicle?
| What does LH do in the ovary corpus luteum?
in the ovary, it increases ovulation and formation of corpus luteum
in the ovary corpus luteum, there is increased estrogen and progesterone synthesis
50
What does LH do in the Testis?
increases testosterone synthesis
51
Growth hormone and prolactin belong to the same (blank)
gene family
52
What kind of hormones are growth hormone and prolactin?
polypeptide hormones
53
How big are growth hormones?
190 AA
54
How many types of prolactin are there, how big is prolactin, how do you change the size of your prolactin?
3
190 AAs
remove disulfide bonds
55
```
What increases ;
growth
IGF-i production
protein synthesis
glucose utilization
fat utilization?
```
growth hormones, works on most tissues
56
What increases milk secretion, growth of mammary glands, and decreases GnRH?
Where does this work?
prolactin
| Mammary glands and hypothalamus
57
(blank) is the organized addition of new tissue that occurs normally in development.
growth
58
(blank) involves genetic, nutritional and environmental factors as well as actions of the endocrine system.
Growth
59
Why is growth hormone different from other anterior pituitary hormones?
It exerts its effects directly on almost all tissues of the body (not a specific gland)
60
Explain skeletal growth
proliferation of epiphyseal cartilage
increased conversion of cartilage to new bone
increased bone thickening
increased bone remodeling
61
When does increased conversion of cartilage to new bone (i.e increased length of long bone and skeleton) end?
ends when epiphyses of long bone fuse with shafts
62
What is the proliferation of periosteal osteoblasts?
increased bone thickening
63
What does GH do to metabolism?
```
Increased protein synthesis
decreased protein breakdown (BUN)
Increased fat utilization
decreased glucose uptake and utilization
increase glucose production by liver
```
64
What does GH do to body organs?
increases size and number of cells and causes specific differentiation of certain cell types
65
Some growth effects of GH are mediated by (blank)
IGFs (insulin-like growth factors)
66
What are somatomedins?
insulin-like growth factors
67
Where is somatomedins created?
in liver and at local site of action (i.e bone and tissues)
68
What do somatomedins do to chondrocytes and osteoclasts?
stimulate both of these thus increase bone elongation
69
What is the most important IGF?
Somatomedin C (IGF-I)
70
If you dont have IGF-I (somatmedin C) what will happen?
you will be a dwarf or pygmie
71
Is there a negative feedback mechanism for growth hormone secretion?
yes
72
When is GH secretion stimulated?
```
GHRH
Ghrelin
Decreased blood glucose
Decreased blood fatty acids
exercise
excitement
trauma
estrogen and androgens
sleep
```
73
When is GH secretion inhibited?
```
somatostatin
obesity
increased blood glucose
increased blood fatty acids
aging
somatomedins (IGF)
Growth hormone (-ve feedback)
```
74
What causes panhypopituitarism in the adult?
pituitary tumors, thrombosis of pituitary blood vessels, trauma
75
What are the effects of panhypopituitarism in adults?
```
lethargy (hypothyroidism),
weight gain (lack of adrenocortical and thryoid hormones)
loss of sexual function (decreased gonadotropic hormones)
```
76
What is the treatment for panhypopituitarism?
thryoxine, cortisol
77
What is the cause of dwarfism?
congenital defect
pituitary tumor
trauma causing panhypopituitarism (decreased secretion of all anterior pituitary hormones)
isolated GH or IGF-I deficiency
78
What is the effect of dwarfism?
slow and reduced growth (around 4 ft)
juvenile appearance
if due to panhypo.... then hypothyroidism, hypogonadis, and low glucocorticoids
79
What is the treatment for dwarfism?
human GH, thyroxine, cortisol
80
What does GH hypersecretion in ADOLESCENSE result in?
gigantism
81
What is the cause of gigantism?
hyperactivity of otherwise normal cells
| or pituitary tumor happening during adolescence
82
What is the effect of gigantism?
Rapid growth of all tissues
| hyperglycemia (sometimes get diabetes)
83
What is the treatment of gigantism?
somatostatin analogs, surgery
84
In general, excessive growth hormone can cause (blank) and (blank) due to metabolic disturbances.
ketosis
| insulin resistance
85
What is acromegaly?
GH hypersecretion in the adult
86
What is the cause of acromegaly?
Pituitary tumor after adolescence
87
What are these the effects of:
bones grow in thickness (not length),
enlargement of nose, cranium, supraorbital ridges, mandible, vertebrae (kyphosis), enlargement of hands and feet, elongation of ribs, enlarged tongue, liver, kidneys, heart, diabetes.
acromegaly
88
What is the treatment of acromegaly?
somatostatin analogs, surgery
89
Do humans have an intermediate lobe?
no
90
What does the pro-opiomelanocortin family do?
it gets cleaved by POMC endopeptidases
91
What will cleavage of the pro-opiomelanocortin family create?
B-lipotropin
ACTH
y-lipotropin
92
Where does ACTH come from and what does it do?
it comes from cleavage of POMC and targets the adrenal cortex to increase synthesis and secretion of adrenal cortical steroids
93
Where does B-lipotropin come from and what does it do?
comes from the cleavage of POMC and targets fat to increase fat mobilization (little activity in humans)
94
What can ACTH and B-LPH be further cleaved into?
beta endorphins and alpha melaocyte stimulating hormones
95
When ACTH levels are increased, (blank) can be produced and may lead to hyperpigmentation of the skin via its effect on melanocytes.
alpha-MSH
96
(blank) plays a role in appetite regulation and sexual behavior
Alpha-MSH
97
What is prolactin inhibitory hormone also called?
dopamine agonist
98
(blank) is a peptide synthesized from a 92 AA preprohormone
GnRH
99
(blank) is a 44 AA peptide.
GHRH
100
(blank) are preprohormone cleaved into 2 active formes (one 14 AA , one 28 AA)
SS
101
(blank) is synthesized as a 242 AA peptide with 6 copies of the hormone sequence cleavage.
TRH
102
(blank) is an amine formed by removing a carboxyl group for a molecule of L-DOPA
DA
103
(blank) is a 41 AA peptide derived from a 196 AA preprohormone
CRH
104
What does SS do?
It inhibits growth hormone
105
What does this:
| ↑ Synthesis & secretion of thyroid-stimulating hormone (TSH) & prolactin (PRL)
TRH (thyrotropin releasing hormone)
| peptide structure
106
What does this:
| ↑ Synthesis & secretion of luteinizing hormone (LH) & follicle-stimulating hormone (FSH)
GnRH (gonadotropin-releasing hormone)
| peptide
107
What does this:
| ↑ Synthesis & secretion of adrenocorticotrophic hormone (ACTH)
CRH (corticotropin-releasing hormone)
AVP (arginine vasopressin)
(peptide)
108
What does this:
| ↑ Synthesis & secretion of growth hormone (GH)
Growth hormone releasing hormone (GHRH)
| peptide
109
What does this:
| ↓ GH secretion
Growth hormone inhibitory hormone (PHIH, somatostatin)
| peptide
110
What does this:
| ↓ Synthesis & secretion of prolactin (PRL)
Prolactin-inhibiting hormone (PIH)
| amine
111
What is the amine hormone of the hypothalamic releasing hormones?
prolactin inhibiting hormone
112
Hypothalamic releasing/inhibitory hormones are secreted in the hypothalamus and collect in the (blank)
median eminence
113
Where do the hormones secreted by the hypothalamus go?
collect in median eminence and then head into portal system and are conducted to anterior pituitary where they influence secretion from glandular cells
114
The (Blank) blood flow only represents a tiny fraction of the cardiac output/
hypophysial portal
115
The (blank) artery supplies the posterior lobe of the pituitary gland
inferior hypophyseal
116
The (blank) artery supplies the anterior lobe and the infundibulum of the pituitary gland and median eminence of the hypothalamus and gives rise to the hypophyseal portal system
superior hypophyseal
117
What join up together to create the median eminence?
Superior hypophyseal and inferior hypophyseal
118
Where is there a release of hormones from hypothalamus into the portal system?
the median eminence
119
What is a fast and highly specific and uses the hypothalamus to regulate hormone secretion?
neuroendocrine
120
Several hypothalamic hormones are released in a (blank) fashion but only GnRH release is critical for pituitary (gonadotropin) secretion
pulsatile
121
What is critical for pituitary (gonadrotropin) secretion?
pulsatile GnRH secretion
122
WHen GnRH is released by hypothalamic neurons what happens in the anterior pituitary?
LH is released
123
(blank) is a collecting center for environmental and sensory information.
hypothalamus
124
Release of hypothalamic releasing/inhibitory factors can be influenced by (blank)
```
pain
emotions
light and dark
sleep
exercise
electrolytes
hormones
```
125
What are the three feedback loops that the anterior pituitary is a part of?
long loop negative feedback
ultra-short loop negative feedback
short loop negative feedback
126
(blank) is the regulation of a systemic hormone on the hypothalamus or pituitary
Long loop negative feedback
127
What is this:
CRH secreted from hypothalmus→
ACTH secreted from anterior pituitary→
Cortisol secreted from adrenal cortex;
THEN
Cortisol inhibits ACTH release and CRH release.
example of long loop negative feedback
128
(Blank) is when pituitary hormones act upon the hypothalamus
short loop negative feedback
129
What is this:
Example:
CRH secreted from hypothalmus→
ACTH secreted from anterior pituitary;
THEN
ACTH inhibits CRH release.
short loop negative feedback
130
(blank) is when the hypothalamic or pituitary hormones directly regulate the cells that secrete the hormone.
ultra short loop negative feedback
131
What is this:
CRH secreted from hypothalmus;
THEN
CRH inhibits further CRH release.
Ultra-short loop negative feedback
132
(blank) are classified as primary, secondary, or tertiary.
endocrinopathies
133
Endocrinopathies at the level of target organ is (blank)
primary
134
(blank) is a disease marked by dysfunction of an endocrine gland. Excess/insufficiency of hormone or binding to receptors.
endocrinopathies
135
An endocrinopathy at the level of pituitary.
secondary
136
An endocrinopathy at the level of hypothalamus
tertiary
137
ADH (vasopressin) and oxytocin are secreted by the (blank)
posterior pituitary
138
The posterior pituitary is primarily comprised of (blank). These cells do not secrete hormones.
glial cells called pituicytes
139
Do pituicytes (glial-like cells) secrete hormones?
no
140
Hormones of the posterior pituitary are secreted by (blank)
neurons
141
The hormones secreted by neurons into the posterior pituitary have their bodies located in the (blank)
hypothalamus
142
The hormones that are secreted in the posterior pituitary are synthesized in the cell bodies of the hypothalamus and transported down the nerve (blank) into the posterior pituitary.
axons
143
ADH and oxytocin are similiar in structure differing by only (blank) AAs
2
144
```
What is the structure of oxytocin?
where is its origin?
What is its half-life?
What is its function?
Binding carrier protein?
```
nonapeptide
magnocellular neurons in the paraventricular nuclei
~2 min
Milk ejection and hastens delivery (promotes delivery of placenta, reduces bleeding, contracts uterine smooth muscle)
neurophysin I
145
Is oxytocin the physicological trigger for parturition (giving birth)?
no
146
```
What is the structure of ADH?
where is its origin?
What is its half-life?
What is its function?
Binding carrier protein?
```
```
nonapeptide
magnocellular neurons in the supraoptic
2 mins
reabsorption of water and vascular smooth muscle contraction
Neurophysin II
```
147
What does ADH do molecularly?
Reabsorption of water:
v2 receptor-> cAMP-> insertion of aquaporin into luminal membrane of collecting tubule
Vascular Smooth muscle:
V1 recptor-> IP3-> DAG-> increased Ca2+
148
What is this:
Problem: Unable to conserve water due to ↓ADH synthesis (central DI) or insensitivity to ADH at the collecting ducts (nephrogenic DI)
Causes: trauma, tumors, infection (e.g. meningitis)
Principle symptoms: ↑water loss from kidneys (polyuria) triggers ↑ thirst (polydipsia)
diabetes insipidus
149
What is this:
increased Water retention-> atria of heart stretched-> increased ANF, decreased plasma renin activity-> sodium loss-> hyponatremia and decreased plasma osmolality; concentrated urine
Causes: Ectopic: ADH secreted from lung cancer, etc.
Eutopic: Stroke, infection
Principle symptoms: asymptomatic during early stages especially if serum sodium falls slowly. Rapid fall associated with confusion, drowsiness, convulsions, coma and death.
Syndrome of inappropriate ADH secretion
| SIADH
150
```
What is this:
Causes:
Damage from malnutrition (e.g. anorexia, bulimia),
Genetic disorders,
Radiation,
Surgery,
Head trauma,
Lesion,
Tumor,
Other physical injury to the hypothalamus.
```
```
Effects - disruptions in:
Body temperature regulation,
Growth,
Weight,
Sodium and water balance,
Milk production,
Emotions,
Sleep cycles.
```
```
Associated conditions:
Hypopituitarism,
Neurogenic diabetes insipidus (not enough ADH),
Tertiary hypothyroidism,
Developmental disorders.
```
Hypothalamic disease
151
What is this:
Abnormal growths that develop on the pituitary gland (10mm – macroadenoma)
Usually benign adenomas
May produce excess hormone or restrict activity of the pituitary to lessen hormone production
May be removed surgically - endoscopic transnasal transsphenoidal approach (most common), transcranial approach (craniotomy) for larger tumors.
pituitary gland tumors
152
What is the most common pituitary gland tumor?
| What is the most rare pituitary gland tumor?
prolactinomas
| rarely thyrotroph adenomas
153
(blank) is increased prolactin, increased milk production, decreased reproductive function (can manifest as hypogonadism
prolactinomas
154
(blank) is increased GH, increased bone/soft tissue growth, acrogmegaly.
somatotrophic adenomas
155
(blank) is increased ACTH and increased Cortisol (cushings syndrome symptoms)
corticotrophic adenomas
156
(blank) is decreased LH and FSH
gonadotrophic adenomas
157
(blank) is rare, usually large when diagnosed and the most rare pituitary gland tumor.
thyrotrophic adenomas
158
Sometimes when you have a pituitary gland tumor what can happen to your eyes?
visual impairment because tumor is compressing optic nerve
159
What is a complication of surgical removal of a tumor of the pituitary gland?
may permanently alter hormone supply
160
ACTH deficiency would lead to (blank)
adrenal (cortisol) insufficiency
161
TSH deficiency would lead to (blank)
hypothyroidism
162
Gonadotropin deficiency will lead to (blank)
hypogonadism
163
GH deficiency can result in what?
failure to thrive and short stature in child (dwarfism);most adults are asymptomatic and some may experience fatigue and weakness and decreased quality of life.
164
What can ADH deficiency lead to?
polyuria and polydipsia
165
What are these:
ACTH deficiency - Adrenal (cortisol) insufficiency
TSH deficiency - Hypothyroidism
Gonadotropin deficiency -Hypogonadism
GH deficiency - Failure to thrive and short stature in children (pituitary dwarfism); most adults are asymptomatic, but some may experience fatigue and weakness and decreased quality of life
ADH deficiency - Polyuria and polydipsia
Other presenting features may be attributable to the underlying cause. A patient with a space-occupying lesion may present with headaches, double-vision, or visual-field deficits.
A patient with large lesions involving the hypothalamus may present with polydipsia/polyuria or, rarely, syndrome of inappropriate secretion of antidiuretic hormone (SIADH).
Pituitary hormone insufficiency
