Section 6 Endochrinology Introduction Flashcards
List glands:
pineal gland, anterior pituitary, thyroid,parathyroid, thymus, pancreas, adrenal cortex, adrenal medulla, testes, ovaries, placenta
Hypothalamus, gland or cell?
clusters of neurons
Posterior pituitary, gland or cell?
Extensions of hypothalamic neurons
List all that belong to the peptide class:
hypothalamus, posterior pituitary, anterior pituitary, parathyroid, thymus, heart, liver, stomach and small intestines, pancreas, adipose tissue
List those that are steroids/ peptides:
testes, ovaries, placenta
List those that are peptides/ steroids:
kindey
List those that are amines:
pineal gland, adrenal medulla
List those that are steroids:
adrenal cortex, skin
List those that are iodinated amines/ peptides:
thyroid
2 sites of hormonal control that feedback to the hypothalamus:
Trophic hormone (H2) and Hormone (H3)
To where, besides the hypothalamus does Hormone (H3) feedback?
anterior pituitary
Complex polypeptides are composed of more than:
20 aa’s
Simple polypeptides are composed of less than:
20 aa’s
Amino acid derivatives:
single amino acid derivatives, iodothyronines
Cholesterol derivatives:
intact steroid nucleus, Vit D
True or False? Both water soluble and water insoluble hormones can be transported in the blood stream.
T
Water soluble hormones that can be transported via the blood stream:
peptides, amino acids
Water insoluble hormones that can be transported via the blood stream:
iodothyronines, cholesterol derivatives
2 types of cholesterol derivatives:
specific binding proteins and general binding proteins
Give an example of a specific binding protein:
thyroid binding globulin (TBG)
Give an example of a general binding protein:
albumin
Which endocrine organ(s) use(s) restricted circulation as its’ delivery method?
pituitary gland
Which endocrine organ(s) use(s) target cells adjacent to release cells - cell to cell communication as its’ delivery method?
Paracrine organs, ie gonads
Different methods of response to hormonal action:
specific receptors or local activation (inactivation) of hormone
What is hormone action dependent upon?
blood concentration, target cell receptors number, hormone-receptor affinity
Hormone action affects target cell by changing:
enzyme activity, proteins synthesis, transport, secretion rate
Signal transduction mechanisms:
receptor - transducer - amplifier - messenger
4 pathways of signal transduction:
cAMP (intracellular), Phosphatidylinositol (PIP2) turnover (Ca++/ proteins kinase C system), steroid action and intracellular receptors, tyrosine kinase receptors
3 types of cellular interactions:
permissive interactions, synergistic interactions, and inhibitory interactions
Example of permissive interactions?
without the presence of hormone B, hormone A has littler or no effect. Hormone B is said to have permissive action.
Explain synergistic action:
The effect of the two hormone together is greater than the sum of the individual effects force each hormone
Explain inhibitory interactions:
action of one hormone opposes the action of a second hormone
Main components of the thyroid gland:
follicular cells and colloid
Colloid is aka:
thyroglobulin
What surrounds the follicular cells with the colloid center?
capsule of connective tissue
What other type of cell is interspersed with the follicular cells of the thyroid gland?
C cells
T(4) is:
Thyroxine
T(3) is:
Triiodothyronine
T(3) and T(4) are both made from:
Tyrosine
Roles of iodide:
transport, peroxidase, iodination
Path of iodine in the thyroid gland:
transported from blood, through cell, to the colloid to combine with thyroglobulin (composed of both T3 and T4, right?), which is then transported in vesicles back into the cell for storage
Actions of Thyroxine:
T4 vs. T3 vs. rT3, growth and development, metabolic effects, sympathetic nervous system, temperature regulation
In which parts of the body does thyroxine play a role in growth and development?
skeletal system and central nervous system
Metabolic effects of the thyroxine:
increased basal metabolic rate (plasma membrane Sodium, K+ - ATPase, increased carbohydrate and fat utilization (demand driven), increased protein synthesis (excess leads to degradation)
Role of thyroxine in the sympathetic nervous system:
increased sensitivity to catecholamines
Pathology of the thyroid gland:
Hyper/ hypothyroid
What other issues are related to Hyperthyroidism?
Grave’s disease (auto immune); neoplasm or autonomous nodule
Symptoms of hyperthyroidism:
high body temperature, excessive sweating, heat intolerant, weight loss, weakness, high heart rate, atrial arrhythmia’s, tremor, nervousness, wide-eyed stare
Issues related to hypothyroidism:
Hashimoto’s disease (autoimmune; iodine deficiency; ablation; pituitary or hypothalamic deficit; perinatal deficit - cretinism))
Symptoms of hypothyroid:
low body temperature, dry skin, cold intolerant, weight gain, puffy appearance, low heart rate, lethargy, sleepiness, lowering of the upper eye-lid, slow speech
Master gland:
pituitary gland
Ca++/ pH hoemostasis:
parasympatheticthyroid
Steroid factory:
adrenal cortex, 10g
postganglionic system, extension of sympathetic nervous system:
adrenal medulla
glucose homeostasis:
glucocorticoids, norepinephrine and epinephrine
Autonomous endocrine gland:
placenta, not controlled by any other tissue
End product inhibition:
negative feedback mechanism
to get to pituitary:
roof of mouth to extract adenomas, outputting of brains
2 tissues of pituitary gland:
anterior and posterior pituitary
Projection from hypothalamus
d
Posterior pituitary produces:
oxytocin and ADH (Vasopression)
Neural lobe (neural hypophesis)
Posterior pituitary
endocrine tissue of pituitary gland
anterior pituitary, not neurally derived, 6 hormones
synapse:
onto capillary bed, dumping contents here, blood supply drains the hormones that are being released
How many types of cells are secreting the 6 hormones of the anterior pituitary gland?
5
Posterior pituitary produces:
oxytocin and ADH (Vasopression)
Neural lobe (neural hypophesis)
Posterior pituitary
endocrine tissue of pituitary gland
anterior pituitary, not neurally derived, 6 hormones
cell bodies lie here:
hypothalamic nuclei
synapse:
onto capillary bed, dumping contents here, blood supply drains the hormones that are being released
How many types of cells are secreting the 6 hormones of the anterior pituitary gland?
5
This hormone, released from the pituitary gland is endorphins:
ACTH
What type of gland is the thyroid gland?
permissive
functions of epithelial cells around follicular cells:
thyroid hormones, proteins, globulins that are secreted into the colloid
Thyroid hormones first enter this space:
colloid space
What type of process is used for the release of thyroid hormones?
Double secretion process
True or False? Thyroid hormones are lipophilic
T
What is thyroid hormone stored?
must be bound, can not easily be stored because it leaks out, bound to glycoprotein in the colloid space
Chemical origin of thyroid hormones:
tyrosine, water soluble
What is required for biological activity of T3 and T4?
idoine
What differs between T3 and T4?
number of iodinated positions
T3 has complete biological activity:
F.
Which has less biological activity, T3 or T4
T4
How can T4 be made morphology active?
Deiodinate to make T3
T4 is essentially a:
prohormone
Composition of T3:
2 tyrosine + 3 iodine
What type of receptors for T3?
nuclear receptor
Thyroid hormones are ___-like compounds.
steroid
What is necessary to make type hormone?
iodine
True or False? We can synthesize iodine.
F.
What cells transport iodine?
follicular cells
What type of transport for iodide?
Sodium/iodid transporter, ATP required to increase conc of iodine 2-30 times up to 200 times
What happens at the same time as iodide transport not the cell?
synethiss of thyroglobuid (major component of colloid), binding protein to keep the constituents from floating away because they are lipophilic
From where to where is thyroglobulin secreted?
follicular cell to colloid space
What are the branches coming off of thyroglobulin?
tyrosine
Where is thyroglobulin iodinated
apical side of follicular cell
Pendrin:
transporter to move iodide into the colloid from follicular cell
What is required for idode to bind to Thyroblobulin?
Must be reactive enough to couple with tyrosine backbone, done by peroxidase and then iodination (peroxidation, essentially a free radical)
How many steps is thyroid peroxidase enzyme involved in?
perixidation, iondination (in presence of thyroid peroxidase), and coupling (stack to tyrosine molecules together)
What stimulates the grabbing up of colloid (uptake process of colloid)
pituitary
What causes the degradatin of the colloid structure?
fusing with lysosomes (proteases, etc.), indiscriminant digestion
Product of the degradation of thyroglobulin:
T1, T2, T3, T4,
True or False? T1 and T2 are lipophilic.
F
What happens to the T3 and T4 that is broken down from thyroglobulin?
released into circulation via transporters
how much more T4 is being released into the circulation than T3
20 times more
What enzyme in the tissues can snip off iodine?
deiodinases
Functions of in the biosynthesis force thyroid hormone:
TSH stimulates the transporter involved, 10 -250 fold increase of activity
TRH release TSH from:
anterior pituitary gland
True or False? All the breakdown products of thyroglobulin can be recycled.
T
What releases the major hormones for thyrotroph activation?
hypothalamus (TRH into portal circulation)
What stimulates the thyroid follicles?
TSh
What is inhibitory of thryotroph secretion of TSH?
T3, T4 would bind to thyrotroph and be converted to T3 and then act on thyrotroph
Actions of thyroid hormones:
transport via: thyroxine binding globulin (TBG), growth (chondroenic, not directly involved in linear growth), metabolic, sympathetic nervous system, temperature regulation
What binds most hormones to transport to the periphery?
albumin
What can bind to TBG (specific)?
T3 and T4
T3 can alter:
genomic functions
What happens to T4 in the periphery?
iodinated to T3
IGF1:
involved in linear growth
Dental connection
Tooth eruption
In utero, if mom is iodide deficient:
can result in demyeleniatoin that leads to retardation and cretinism
True or False? The effects of iodide deficiency is reversible after birth
T
Metabolic effects of thyroid hormones:
accelearated starvation, Vo2 increase, more fuel demand,, transport more across GI tract
What can happen in hyperthyroidism?
the system becomes catabolic, extreme starvation, loss of u to 50% of proteins stores
What muscles are affect most in hyperthyroidism?
quads, metabolic breakdown of tissues
How can you increase heart rate and blood pressure in an animal?
postsynaptic effect, permissive effect of thyroid hormones on therapy heart, increased beta receptors density (thyroid hormones maintain these), release of norepinephrine from sympathetic terminal to there heart, greater response in heart rate and contractility
Overload of thyroid hormones leads to an increase in:
increase in beta receptors
hashimotos’s thyroiditis:
destruction of the thyroid gland
No idodie in diet leads to:
low thyroid hormone release, normal negative feedback system is not there, primarily colloid production will be unregulated. If stimulation is larger and strong enough you will have an increase in the size of the thyroid
Graves disease;
TSI’s, autoimmune process that attacks thyroid gland, binds follicles and turns them on permanently, follicles are in overdrive, iodinating,etc. You are making active thyroid hormone, primary driver is some autoimmune process. Pumping out T3 and T4 which will have their effects, intense feedback on anterior pituitary and shut down of the hypothalamus.
Both Hashimoto’s thyroiditis and Grave’s disease lead to:
goiter, enlarged thyroid
