Lecture 10 Flashcards
Thyroid gland
Largest endocrine gland, has two lobes, located anterior on the neck underneath the larynx of the voice box, and produce 2 hormone
The two lobes of the thyroid gland is connected by a narrow tissue called
Isthmus
The two hormone made by the endocrine gland
T3 triiodothyronine and T4 tetraiodothyronine(thyroxin)
Between T3 and T4 which is produced more
93% of the hormones made are T4 but later converted to T3
The thyroid gland controls
BMR basal metabolic rate
Thyroid stimulating hormone
TSH is produce in the pituitary gland and controls thyroid directly.
TSH is produced
In the adenohypophyseal of the pituitary gland
Para follicular cells
Release thyrocalcitonin that lowers ca level in the blood
Follicular cells
Synthesizes an inactive hormone that is a glycoproteins (thyroglobulin) with mainly tyrosine residue
Thyroglobulin
A precursor to the iodinated T3 and T4 protein
Parathyroid glands are also found in the
Thyroid glands with two in each lobe making 4 parathyroid
The hormone produced by the parathyroid glands and it function
PTH to control ca levels
Hypothyroidism
Caused by not enough iodine, it is acquired through diet, only 1/5 of the iodine is absorbed and the rest is excreted through the kidneys
TSH is the driving force of
Iodide trapping of the thyroid follicular cells
During iodide trapping the cell
Becomes 30 times more concentrated with I- in the cytoplasm
Before organification can occur
Thyroglobulin protein are synthesize they brought to lumen side of cell by exocytosis
Organification is the
Adding of iodine to thyroglobulin at the apex of the cell
After organification
The compound is taken up by the cell by endocytosis and goes into the lysosomes of the cell to be cleaved furthermore changing them to an active T3 or T4 hormone
T3 and T4 can diffuse through the membrane into the bloodstream because they are
Fat soluble
After diffusing through the membrane T3 and T4
They bind to the protein thyroxine
Thyroxine -binding protein
A protein that binds to T3 and T4 in the bloodstream to inactivate them. This protein is synthesize in the liver
NIS (sodium iodide symportor)..
A carrier protein that utilizes secondary active transport to move Na+ and 1I- into the cell
Pendrin
A counter proter that moves one cl into the cell and one I - out of the cell at the lumen side of the thyroid follicle cell
Iodanase
An enzyme that attaches iodide to the residues of thyroglobulin proteins will eventually become either T3 and T4. It changes T4 to T3
Organification
Attachment of iodide to the thyroglobulin protein
Retinoids
T3 goes into the nucleus and it binds to retnoid x
Retnoid x
A heterdimer protein that is transcription factor. It make the cell produce more proteins. Retnoid x has a specific Binding site on the DNA
Response element ( thyroid hormone response element )
Retnoid x has specific binding site on the DNA
What vitamins also binds to retnoid x
Vitamin D
Non genomic effects of T3
Increase basal metabolic rate which keeps you alert , causes an increase in cellular respiration, increase protein synthesis and catabolism, increase the number of mitochondria , increase carbohydrate metabolism, it can have an have an opposite effect if the person is deficient in iodine , therefore making them lethargic depressed, low heart rate, and no ambition to do anything
Other effects of T3
Promote rise of insulin, promote gluconeogenesis, promote fat metabolism, promote cardiovascular system, respiratory rate change, Co2 concentration goes up
TSH receptors are located
On the surface of the thyroid follicular cells
Binding of the TSH to the receptor causes
An elevation of cAMp which is a secondary messenger
Rise in cAmp in the thyroid cells affects
NIS, iodination process, endocytosis of thyroglobulin, breakdown of thyroglobulin, and the size of the thyroid cells.
TSH is synthesis when
Thryroid releasing hormone( TRH) is deposited into the pituitary gland by the hypothalamus
The elevation of ca occurs when
TRH receptor activates a G protein which would then activate an enzyme phospholipase that breaks down IP3 which causes an influx of ca
Short loop feedback involves
The pituitary gland reacting to the excessive or deficient thyroid hormone
Long loop involves
The hypothalamus reacting to the excessive or deficient thyroid hormone
The primary feedback of the thyroid gland is
The short loop
Rumors on the thyroid gland cause
More production of T3 and T4
Grave disease
Autoimmune disease that produces TSI thyroid stimulating immunoglobulin. it attaches to TSH receptor and acts as an agonist to TSH
Hyperthyroidism
Caused by high levels of thyroid hormones, symptoms include weight loss high metabolism rate, insomnia hand tremors, muscle weakness increase blood pressure, high heart rate and hyperactive.
Hypothyroidism
Caused by low levels of the thyroid hormones. Symptoms are opposite of hyperthyroidism linked to hashimoto disease
Hashimoto diseas
Autoimmune disease that causes hypothyroidism, the antibody starts attacking the thyroid follicle cells. Treatment involves a drug called synthroid
Synthroid is
A drug that mimics the T4 and T3. This is a replacement therapy for goiter
Goiter
Enlargement of thyroid due to deficieny of thyroid hormone
Adrenal glands is located
On the kidney
The nervous system of the adrenal glands
Is a modified sympathetic nervous system where the neurons have lost their their fiber
The neuron fiber of adrenal glands release nor epinephrine or epinephrine at …………..and acetylcholine at ………….
Post synaptic and pre synaptic cleft
Adrenal glands are stimulated by
ACTH
Adrenal glands produce
Adrenocoticoid hormones which are glucocorticoid, cortisol, mineralo corticoid, aldosteron, androgen
The adrenal gland has two layers
Medulla and the cortex
The layer of the cortex are
Zona glomerulosa, zona fasciulata, and zona reticularis
Glucocorticoid is responsible for
Regulation of metabolism of glucose(increase glucose in the blood) are part of the feed back mechanism in the immune system that turn immune activity(inflammation) down use to treat over active immune system.
Cortisol
It is released in response to stress and low level of the blood, it primary functions are to increase blood sugar through gluconeogenesis, supress the immune system, aid in fat,protein and carbohydrate metabolism, it also decrease bone formation
Mineralo corticoid
Deals with the balance, particularly Na and k
Aldosterone
Increase the reabsorption of sodium ions and water and the release of potassium in the collecting duct and distal convoluted tubule of the kidney functional unit nephrons . This increase blood volume therefore increasing blood pressure
Adrogen
Aka adrogenic hormone or testoid, it is the term for any natural or synthetic compound, usually steroid hormone. That stimulates or controls the develop and maintenance of male characteristic by binding to the adrogenic receptors
Zona glomerulosa produces
Aldosterone, it is very responsive to angiotensin 2, second largest layer
Zona fasciulata produces
Cortisol, corticosterone, glucocorticoid, the largest gland, produces small amount of androgen and it is affected by adrenocortical tropic hormone(ACTH)
Zona reticularis produces
Androge, dehydro epiangie steroid DHEA, small amounts of glucocorticoid and estrogen
Cortisol and corticosterone are what type of hormone
Stress hormones
