Endocrinology Flashcards
All lectures. Not done with ENDO 3 or 4 yet as of 2/19
What are features of the endocrine system?
Provides “broadcast’ regulation of
many tissues; specificity due to
receptors
Slower but longer lasting responses
compared to the NS
What are the functions of hormones?
- Maintenance of homeostasis
- Growth and differentiation
- Reproduction
What are some specialized endocrine glands?
- Pituitary Gland
– Thyroid Gland
– Parathyroid Gland
– Adrenal Gland
– Pineal Gland
Can organs secrete hormones even if that’s not their purpose?
Yes
What are the classes of hormones?
- Proteins and Polypeptides
- Steroids
- Derivatives of Tyrosine
How are protein hormones first synthesized as?
Preprohormone
What is preprohormone converted into?
Prohormone
What happens to the prohormone?
Packaged into vesicles, then cleaved into active hormone
Where do steroid hormones come from?
Adrenal cortex, ovaries, and testes
What are steroid hormones synthesized from?
Cholesterol
What happens when a steroid hormone is needed?
Synthesized on demand (it is not stored)
What are amine hormones derived from?
Tyrosine
What are some examples of amine hormones?
Epinepherine and norepinepherine
Are amine hormones stored?
Yes, then released as needed
What do thyroid hormones bind to?
The protein thyroglobulin
How are epinepherine and norepinepherine secreted?
Stored in vesicles, then released by exocytosis
How can hormones circulate?
Freely or bound to carrier proteins
What are carrier proteins called?
Binding proteins
What are example of binding proteins?
Albumin, thyroxine-binding globulin
What are features of growth hormone excess?
Coarse facial features,
large fleshy nose,
frontal bossing, jaw
malocclusion.
What is growth hormone excess in children called?
Gigantism
What is growth hormone excess in adults called?
Acromegaly
What is the treatment for a Pituitary Microadenoma?
Surgical resection of the tumor (adenomectomy)
via transphenoidal approach followed by
medication (somatostatin (GHIH) receptor ligand
or GH receptor antagonist)
What are some of the oral manifestations of GH Excess?
Thick rubbery skin, enlarged nose,
and thick lips; Macrocephaly; Macrognathia; Disproportionate mandibular growth; Mandibular Prognathism; Generalized Diastemata; Anterior open bite and malocclusion (macrognathia and tooth migration)
Does GH Excess cause sleep apnea?
Yes, through hypertrophy of the pharyngeal and laryngeal tissues
What are some causes of GH deficiency?
Hypothalamic disorders
Mutations: GHRH receptor, GH gene, GH receptor, IGF-1 receptor
Combined pituitary hormone deficiencies (panhypopituitarism)
Radiation
Psychosocial deprivation
What are the clinical manifestations of GH deficiency?
slow linear growth rates
* normal skeletal proportions
* pudgy, youthful appearance (decreased lipolysis)
* in the setting of cortisol deficiency hypoglycemia
What is the most common form of dwarfism?
Achondroplasia
What is achondroplasia?
autosomal dominant condition
that results from a mutation of FGF-3 receptor in cartilage and brain. This mutation makes
the receptor overly active and it inhibits cartilage growth at growth plates so limb growth is reduced (growth of the trunk of the body is not impacted).
What are the oral manifestations of GH deficiency?
Disproportionate delayed growth of the skull & facial skeleton -> small facial appearance
Solitary Median Maxillary Central incisor
Eruption delayed
Prone to hygiene-related problems
What does the posterior pituitary secrete?
Antidiuretic/Vasopressin and Oxytocin
What is another term for the posterior pituitary gland?
Neurohypophysis
What type of hormones are the ones secreted by the Neurohypophysis?
Polypeptide
What does the Neurohypophysis contain?
~100,000 unmyelinated
axons of neurons whose cells
bodies are in the hypothalamus
(Paraventricular nucleus and
Supraoptic nucleus)
What does vasopressin do to the blood vessels?
Contraction of vascular
smooth muscle via V1
receptors
What does vasopressin do to renal tubules?
- Binds to V2 receptors in
the late distal tubule and
collecting duct.
– Aquaporin-2 (AQP-2)
proteins are then
inserted into the apical
membrane of tubular
epithelial cells, allowing
for water reabsorption
(along with AQP-3 and
AQP-4 on the
What stimulates ADH secretion?
Decreased Blood Volume (Isotonic)
Increased Osmolarity (Isovolemic)
Decreased Blood Pressure
What is hypodypsia?
Decreased or absent feeling of thirst, which results in
reduced intake of water and can cause Hypernatremia
Who gets hypodipsia?
A common problem in elderly people, but is also
associated with lesions in the hypothalamus (thirst
center), head trauma, occult hydrocephalus or
subarachnoid hemorrhage.
What is diabetes insipidus?
ADH imbalance, causes large output of urine
What are the two types of DI?
Neurogenic/Central
– Nephrogenic/Peripheral
What is Neurogenic/Central?
Reduced ADH secretion
What is Nephrogenic/Peripheral?
Lack of kidney response to ADH
What is syndrome of inappropriate ADH?
High levels of ADH, inappropriately elevated
What does oxytocin do?
Stimulates contraction of the
uterus towards the end of gestation.; Causes milk ejection from the breasts in lactation
What is a sign of a disease?
objective evidence
of disease that can be seen or
measured (ex. enlarged
hands, polyuria, tachycardia,
etc.)
What is a symptom of a disease?
measured (they are
subjective) but are reported
by the person
Which thyroid hormone is more potent?
T3 is more potent than T4
What do thyroid hormones do?
impact metabolism
and growth/development. They also
have permisive action on
catecholamines
What are the two active thyroid hormones?
T3 and T4
Which thyroid hormone is secreted more?
93% is T4; 7% is T3
What is the active form of hormone (in relation to binding proteins)?
The free or unbound form
What kinds of hormones circulate freely?
The majority of amines, peptides, and protein hormones
What hormones circulate bound to binding proteins?
Steroid and thyroid hormones
What can affect someone’s plasma hormone levels that is NOT hormone-production related?
Liver deficiency causing problems with binding proteins
Are hormone level stagnant throughout the day?
NO, circadian rhythms… other fluctuations
What is a circadian rhythm?
Rises and falls based off time of day
What is pulsatile secretion?
They “pulse” with their release
What binds to plasma membrane receptors?
Polypeptide, Protein and Amine
Hormones
What binds to nuclear receptors?
Thyroid and steroid hormones
What features do the ligand/receptor demonstrates?
Specificity, affinity and saturation
What determines the location of the hormone receptor?
The properties of the hormone
What are examples of plasma membrane hormone receptors?
- G-protein Coupled
- Tyrosine Kinase: Insulin
- Serine Kinase
- Cytokine: Leptin
What are examples of G-Protein Coupled receptors?
β Adrenergic, Calcitonin,
ACTH, Glucagon, TSH, Vasopressin
What second messenger do Gs-pro c receptors produce?
cAMP
What second messenger do Gq-pro c receptors produce?
P3, DAG and Ca2+
How are receptors distributed throughout the body?
Vary greatly across target tissues to specify tissue activation; however, some are distributed widely (like insulin receptors)
Why do you think these receptors
are more broadly distributed?
They hormones causes a response in more tissue
What are nuclear hormone receptors?
A large family of receptors that are located either in the cytoplasm or
nucleus. All act to increase or decrease gene expression.
What does the hormone receptor complex bind to?
hormone responsive element in the
promoter region of a gene, which leads to
either activation or repression of
transcription.
What are the three types of hormone interactions?
– Antagonism
– Synergistic
– Permissiveness
What are tropic hormones?
hormones that have other endocrine
glands as their targets