Thyroid Gland + Aldosterone+ Androgens Flashcards Preview

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Flashcards in Thyroid Gland + Aldosterone+ Androgens Deck (43)
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1

Aldosterone is a mineralocorticoid
Receptors are present in organs of ___

1.Aldosterone acts on:

uThe ___ convoluted tubules of the ___

uThe __ ___

uThe __ ___

 

2.Inc Na+_ ___

3.Inc K+____

4.Regulated by ___, and ____ ___

 

Acts on kidneys, sweat glands and intestinal mucosa

K will stimulate Aldos secretion

That is bc heart is very sensitive to K. Can trigger ___  which can be deadly.

Angiotensin II also stimulates aldosterone

Aldosterone is a mineralocorticoid
Receptors are present in organs of excretion

1.Aldosterone acts on:

uThe distal convoluted tubules of the kidneys

uThe sweat glands

uThe intestinal mucosa

2.é Na+ retention.

3.é K+  excretion.

4.Regulated by K, and angiotensin II

 

 

 Acts on kidneys, sweat glands and intestinal mucosa

K will stimulate Aldos secretion

That is bc heart is very sensitive to K. Can trigger arrhythmia which can be deadly.

Angiotensin II also stimulates aldosterone

2

Role of aldosterone in regulating blood pressure

Renin angiotensin aldosterone system is very important for regulating blood P and blood volume

If blood volume ___(ECF ____), Decrease BP, Nervous Stimuli, ___, or Urine Na [] , that will be sensed by the___ (JG apparatus)

The kidney will then secrete ____

That will convert ___ to ___

___ will converted I à II

Angiotensin II will stimulate the adrenal cortex to secrete ___

Leads to ____ of Na. Water follows

Will lead to ___ in blood volume

Increase in blood volume will then feed back and ___ this process

Compounds that inhibit converting enzyme will inhibit action of aldosterone (ACE inhibitiors) so important for patients wit ___ BP

nRole of aldosterone in regulating blood pressure

Renin angiotensin aldosterone system is very important for regulating blood P and blood volume

If blood volume falls (ECF depletion), Decrease BP, Nervous Stimuli, NE, or Urine Na [] , that will be sensed by the kidney (JG apparatus)

The kidney will then renin

That will convert angiotensinogenà angiotensin I

Angiotensin converting enzyme will converted I à II

Angiotensin II will stimulate the adrenal cortex to secrete aldosterone

Leads to reabsorption of Na. Water follows

Will lead to increase in blood volume

Increase in blood volume will then feed back and inhibit this process

Compounds that inhibit converting enzyme will inhibit action of aldosterone (ACE inhibitiors) so important for patients with high BP

3

Aldosterone secretion is regulated by the renin-angiotensin system.

1.When the volume or pressure of blood perfusing the kidney___, the ____ cells secrete a proteolytic enzyme renin into the ___ ___

2.Renin cleaves angiotensinogen, a protein from the ___, to form angiotensin I, a __apeptide.

3.Angiotensin I is cleaved by angiotensin converting enzyme (ACE), a peptidase, to form angiotensin II, an __apeptide hormone.

4.Angiotensin II ___ the blood pressure, and stimulates secretion of ___e by the adrenal zona ___a cells.

1.When the volume or pressure of blood perfusing the kidney falls, the juxtaglomerular cells secrete a proteolytic enzyme renin into the blood stream.

2.Renin cleaves angiotensinogen, a protein from the liver, to form angiotensin I, a decapeptide.

3.Angiotensin I is cleaved by angiotensin converting enzyme (ACE), a peptidase, to form angiotensin II, an octapeptide hormone.

4.Angiotensin II raises the blood pressure, and stimulates secretion of aldosterone by the adrenal zona glomerulosa cells.

4

___ in  Plasma K levels can also stimulate aldosterone release

Increase in  Plasma K levels can also stimulate aldosterone release

5

Adrenal Androgens

General info

They are ____: they ___ protein synthesis in peripheral tissues.  This is the opposite of the action of ___

This anabolic action may assist th ___ __ ___ in females

Not very effective in males bc they are overpowered by testosterone

Adrenal Androgens

General info

uThey are anabolic: they increase protein synthesis in peripheral tissues.  This is the opposite of the action of cortisol

uThis anabolic action may assist the pubertal growth spurt in females

 

Not very effective in males bc they are overpowered by testosterone

6

Adrenal Androgens

General info

uThe adrenal androgens can cause ______ if present in excessive amounts.  This may occur as the result of an adrenal tumor

uThe adrenal androgens, especially ______, can serve as the substrate for __ ___ in___ tissue as well as in the ___ ____endocrine glands

u

Adrenal Androgens

General info

uThe adrenal androgens can cause masculinization if present in excessive amounts.  This may occur as the result of an adrenal tumor

uThe adrenal androgens, especially androstenedione, can serve as the substrate for estrogen synthesis in adipose tissue as well as in the estrogen-secreting endocrine glands

u

7

Adrenal Androgens

Adrenal gland secretes both male and female sex hormones in ___ sexes

uDehydroepiandrosterone (DHEA)

FOnly adrenal sex hormone that has any ___ ____

FOverpowered by __ ___ in males

FPhysiologically significant in females where it governs

•Growth of ___ and ___ hair

•Enhancement of __ __ ___

•Development and maintenance of __ __ __

Adrenal gland secretes both male and female sex hormones in both sexes

uDehydroepiandrosterone (DHEA)

FOnly adrenal sex hormone that has any biological importance

FOverpowered by testicular testosterone in males

FPhysiologically significant in females where it governs

•Growth of pubic and axillary hair

•Enhancement of pubertal growth spurt

•Development and maintenance of female sex drive

8

Corticosteroids

uA.  may cause severe inflammatory responses

uB.  stimulate protein synthesis

uC.  increase muscle mass

uD.  may produce hypoglycemia

uE.  Cause fluid retention and edema

u

Corticosteroids

uA.  may cause severe inflammatory responses

uB.  stimulate protein synthesis

uC.  increase muscle mass

uD.  may produce hypoglycemia

uE.  Cause fluid retention and edema

u

9

The thyroid is a composite tissue with several endocrine functions. 
 

Sits like a ___

___ the larynx

The thyroid is a composite tissue with several endocrine functions. 
 

Sits like a bowtie

Below the larynx

10

Unique features of the Thyroid Gland

Only endocrine gland easily ___ and ___

Th are the only ones needing a trace element (___) for production of active hormone

Th is stored ___  in a proteinaceous material called thyroid ___

Th have no cell membrane receptor but act like steroids and bind to ___ receptors

Thyroid hormones require Iodine for their production

Th: Thyroid Hormone

Still protected but its extracellular

Unique features of the Thyroid Gland

Only endocrine gland easily seen and palpated

Th are the only ones needing a trace element (I) for production of active hormone

Th is stored extracellularly in a proteinaceous material called thyroid colloid

Th have no cell membrane receptor but act like steroids and bind to nuclear receptors

Thyroid hormones require Iodine for their production

Th: Thyroid Hormone

Still protected but its extracellular

11

Thyroid follicles: clumps of cells surrounding a lumen filled with colloid.

Follicular cells secrete ___

Parafollicular__ cells secrete ___

Parathyroids (not shown) secrete ___ 

 

Follicular cells secrete this colloidal material and it is in this colloidal material that Th are stored

In order for thyroid hormone to be released have to be reupatken by the follicular cells and passed to the blood stream

PTH regulates Ca

Thyroid follicles: clumps of cells surrounding a lumen filled with colloid.

Follicular cells secrete thyroid hormones

Parafollicular C-cells secrete calcitonin

Parathyroids (not shown) secrete parathyroid hormone (PTH).

 

Follicular cells secrete this colloidal material and it is in this colloidal material that Th are stored

In order for thyroid hormone to be released have to be reupatken by the follicular cells and passed to the blood stream

PTH regulates Ca

12

Thyroid hormones are iodinated amino acids

Made from ___

Tyrosine gets iodinated

Both of these hormones are active but __ is the most active form

In order for hormone to be active, inner ring needs to have 2 I

1 or 2 I on outer ring and you will be active

Inner ring needs 2 I for it to be active

If you have 2 on outer and 1 on inner ringà reverse T3à Inactive

The abundance of hormone in the body is ___

Thryoid Gland releases mainly T4

Within the peripheral tissues T4 gets converted to T3

T4 is a _____. Needs to be converted to T3 to have greater activity

Thyroid hormones are iodinated amino acids

Made from tyrosine

Tyrosine gets iodinated

Both of these hormones are active but T3 is the most active form

In order for hormone to be active, inner ring needs to have 2 I

1 or 2 I on outer ring and you will be active

Inner ring needs 2 I for it to be active

If you have 2 on outer and 1 on inner ringà reverse T3à Inactive

The abundance of hormone in the body is T4

Thryoid Gland releases mainly T4

Within the peripheral tissues T4 gets converted to T3

T4 is a prohormone. Needs to be converted to T3 to have greater activity

13

 

Hormones are stored and attached to protein called ___

T4 is attacheds to thyroglobulin

Stored in___ in this form

When its needed its taken up back into the cell, ___ and that releases the ___

T3, T4 and Reverse T3 are all stored and taken back up

Hormones are stored and attached to protein called thyroglobulin.

T4 is attacheds to thyroglobulin

Stored in colloid in this form

When its needed its taken up back into the cell, cleaved and that releases the T4

T3, T4 and Reverse T3 are all stored and taken back up

14

Thryoid gland is good at concentrating iodine

Iodine doesn't’t have any other purpose in the body

___ moves into the cell along its gradient

E from this will help move Iodide against its gradient into the cell

Iodide gets into cell

Gets taken out of cell

As it passes thru the membrane, we have a ___ enzyme that will oxidize it from ___--> ___

Iodine then gets incorporated into  molecules and these tyrosine molecules are attached to ___

You can have 1 or 2 iodine attached to benzene ring

Then these can ___ to form T3 and T4 or reverse T3

When body needs Th, e___ occurs. cell pinches off a piece of thyroglobulin molecule

Any piece that’s pinched off will have many of these attached.

Fuse with___  enzymes and then those will cleave it from ___  and T3/T4 gets released

Can then go to peripheral tissues

Thryoid gland is good at concentrating iodine

Iodine doesn't’t have any other purpose in the body

Na moves into the cell along its gradient

E from this will help move Iodide against its gradient into the cell

Iodide gets into cell

Gets taken out of cell

As it passes thru the membrane, we have a peroxidase enzyme that will oxidize it from iodideàiodine

Iodine then gets incorporated into tyrosine molecules and these tyrosine molecules are attached to thryoglobulin

You can have 1 or 2 iodine attached to benzene ring

Then these can couple to form T3 and T4 or reverse T3

When body needs Th, endocytosis occurs. cell pinches off a piece of thyroglobulin molecule

Any piece that’s pinched off will have many of these attached.

Fuse with lysosomal enzymes and then those will cleave it from thryroglobulin and T3/T4 gets released

Can then go to peripheral tissues

15

Thyroid Hormones

General Information

uThe parathyroid glands, located ___ the thyroid, secrete parathyroid hormone (PTH).

uThe thyroid gland is made up of ___, clumps of cells that surround a lumen that is filled with colloid.

uThe follicular cells secrete the thyroid hormones, ___ and ____

uBetween the follicles are ___ and parafollicular or C-cells.   The C-cells secrete calcitonin. 

General Information

uThe parathyroid glands, located behind the thyroid, secrete parathyroid hormone (PTH).

uThe thyroid gland is made up of follicles, clumps of cells that surround a lumen that is filled with colloid.

uThe follicular cells secrete the thyroid hormones, thyroxin and triiodothyronine. 

uBetween the follicles are capillaries and parafollicular or C-cells.   The C-cells secrete calcitonin. 

16

Thyroid hormone synthesis and secretion

Synthesis

uUptake of ___ from the bloodstream by ___  transport.

uOrganification: iodide is ___ and incorporated into t___ residues in the protein thyroglobulin producing ___ and ____
 

uSome MIT and DIT residues undergo ___ to form T3 and T4 residues, still in __ ___

uThyroglobulin containing T3 and T4 is ___ in the lumen of thyroid follicles as colloid.

uThyroglobulin is taken  into the cells by ___

uHydrolysis of thyroglobulin to __ ___, including T3 and T4 in the phagolysosomes

uSecretion of __ and ___ into the extracellular fluid.

u

u

Synthesis

uUptake of iodide from the bloodstream by active transport.

uOrganification: iodide is oxidized and incorporated into tyrosine residues in the protein thyroglobulin producing monoiodotyrosine (MIT) and diiodotyrosine (DIT).

uSome MIT and DIT residues undergo coupling to form T3 and T4 residues, still in peptide linkage.

uThyroglobulin containing T3 and T4 is stored in the lumen of thyroid follicles as colloid.

uThyroglobulin is taken  into the cells by endocytosis.

uHydrolysis of thyroglobulin to amino acids, including T3 and T4 in the phagolysosomes

uSecretion of T4 and T3 into the extracellular fluid.

u

u

17

Deficiency of iodineà ____

Deficiency of iodineà Goiter

18

Regulation of Thyroid Hormone

Hypothal: Secretes TRH

TRH gets placed into capillaries and taken to ant pit

TRH binds to thyrotropic cells and these cells secrete TSH

TSH goes to thyroid gland where it has a receptor on follicular cells

Then all of the processes just discussed except the peroxidase activity will occur.

The only process that is not dependent on TSH is____

Hypothal: Secretes TRH

TRH gets placed into capillaries and taken to ant pit

TRH binds to thyrotropic cells and these cells secrete TSH

TSH goes to thyroid gland where it has a receptor on follicular cells

Then all of the processes just discussed except the peroxidase activity will occur.

The only process that is not dependent on TSH is iodideàiodine

19

Regulation of thyroid hormone  secretion

1.The hypothalamus secretes____ releasing hormone (TRH) in response to inputs from the __ __ ___

2.The anterior pituitary secretes ___ in response to ___

3.TSH stimulates ___ and ___ of thyroid follicle cells.

4.TSH stimulates each of the steps in the previous slide.

5.TSH acts via the ___ ___ – __ ___ –___ __ ___ cascade.

6.Thyroid hormones exert___ feedback on secretion of___.  They diminish expression of genes that enable t____s to respond to ___

1.The hypothalamus secretes thyrotropin releasing hormone (TRH) in response to inputs from the central nervous system.

2.The anterior pituitary secretes TSH in response to TRH.

3.TSH stimulates growth and metabolism of thyroid follicle cells.

4.TSH stimulates each of the steps in the previous slide.

5.TSH acts via the adenyl cyclase – cyclic AMP –protein kinase A cascade.

6.Thyroid hormones exert negative feedback on secretion of TSH.  They diminish expression of genes that enable thyrotrophs to respond to TRH.

20

____ is like most of the time inhibitory

Somatostatin is like most of the time inhibitory

21

Thyroid hormones in blood

Thyroid hormones travel in the blood bound to ___

___ __ ___ carries 70-75% of T4.

______ also called______) carries 15-20% of T4.

uSerum ___ carries 5-10% of T4.

uT3 is bound to ___(70-75%) and ___ (25-30%)

u

Thyroid hormones in blood

Thyroid hormones travel in the blood bound to proteins

uThyroid‑binding globulin (TBG) carries 70-75% of T4.

uTransthyretin (TTR, also called thyroid‑binding pre‑albumin, TBPA) carries 15-20% of T4.

uSerum albumin carries 5-10% of T4.

uT3 is bound to TBG (70-75%) and albumin (25-30%)

u

22

Thyroid hormones in blood

In healthy adults ~___% of the T4 is protein-bound.

1.The protein-bound T4 is 100 nM while the free T4 is 0.02 nM.

2.It is the free T4 concentration that correlates with the __ ___ to thyroid hormones.

Binding to transport proteins provides for__ ___ of the hormone to all of the cells along a ____

 

Only freee T3 and T4 are active

Ones that are bound to transport proteins are not active.

They just act as a storage so when more is needed it can be released.

Will take awhile, even if not producing any more Th for that to be used up

Same for T3. 0.05% is free

Thyroid hormones in blood

In healthy adults ~99.98% of the T4 is protein-bound.

1.The protein-bound T4 is 100 nM while the free T4 is 0.02 nM.

2.It is the free T4 concentration that correlates with the physiologic responses to thyroid hormones.

Binding to transport proteins provides for uniform delivery of the hormone to all of the cells along a capillary.

 

Only freee T3 and T4 are active

Ones that are bound to transport proteins are not active.

They just act as a storage so when more is needed it can be released.

Will take awhile, even if not producing any more Th for that to be used up

Same for T3. 0.05% is free

23

Thyroid hormones travel in the blood bound to proteins.

T4

uTBG ( 70-75%)

uTTR (15-20%)

uAbumin (5-10%)

T3

uTBG (70-75%)

uAlbumin (25-30%)

T4

uTBG ( 70-75%)

uTTR (15-20%)

uAbumin (5-10%)

T3

uTBG (70-75%)

uAlbumin (25-30%)

24

Thyroid hormones travel in the blood bound to proteins.

T4

uTBG ( 70-75%)

uTTR (15-20%)

uAbumin (5-10%)

T3

uTBG (70-75%)

uAlbumin (25-30%)

T4

uTBG ( 70-75%)

uTTR (15-20%)

uAbumin (5-10%)

T3

uTBG (70-75%)

uAlbumin (25-30%)

25

Thyroid hormones are activated or inactivated by ____, depending.

Deiodinase enzymes

These are the enzymes that can remove the iodine atom from thryoid hormones

5: Removes iodine from ___ ring

5’: removes from the ___ ring

Thyroid hormones are activated or inactivated by deiodination, depending.

Deiodinase enzymes

These are the enzymes that can remove the iodine atom from thryoid hormones

5: Removes iodine from inner ring

5’: removes from the outer ring

26

Thyroid hormones are activated or inactivated by deiodination, depending.

5’/3’- deiodinases convert thyroxin (T4) to ____, the active form of the hormone by removing I from the outer ring

  Circulating T4 is a ___

The 5/3-deiodinase converts T4 to inactive ___ by removing I from inner ring.

 

Thyroid hormones and their metabolites may be   converted to __ ___ products by coupling them   to ___ ___, and then cleared into the ___

  Persons with their thyroid removed have normal ___  levels if given oral ___ supplements,

 

 

Thryroid hromone are coupled with glucuronic acid and then cleared in the urine

Thyroid hormones are activated or inactivated by deiodination, depending.

5’/3’- deiodinases convert thyroxin (T4) to triiodothyronine (T3), the active form of the hormone by removing I from the outer ring

  Circulating T4 is a prohormone.

  The 5/3-deiodinase converts T4 to inactive reverse T3   by removing I from inner ring.

  Thyroid hormones and their metabolites may be   converted to water-soluble products by coupling them   to glucuronic acid, and then cleared into the urine.

  Persons with their thyroid removed have normal T3   levels if given oral T4 supplements,

 

 

Thryroid hromone are coupled with glucuronic acid and then cleared in the urine

27

Deiodinase enzymes

5’/3’-deiodinase acts on the outer ring

uTwo forms, type 1 present in high conc. In___ ___ ____ and generates ___ of the T3 that reaches the circulation

FType 1 ____by caloric restriction or __ ___and T3 levels ___ and so does ___ __

 

During times of hunger or crisis then a lot of T3 is not produced

High levels of T3 or T4 will ___e the BMR

If you don’t have access to food, why would you want to increase your metabolic rate. You aren’t supplying E to maintain that metabolic rate

Deiodinase enzymes

5’/3’-deiodinase acts on the outer ring

uTwo forms, type 1 present in high conc. In liver, kidney, thyroid and generates most of the T3 that reaches the circulation

FType 1 inhibited by caloric restriction or severe stress and T3 levels decrease and so does metabolic rate

 

During times of hunger or crisis then a lot of T3 is not produced

High levels of T3 or T4 will increase the BMR

If you don’t have access to food, why would you want to increase your metabolic rate. You aren’t supplying E to maintain that metabolic rate

28

Deiodinase enzymes'

uType __ found in___ ___ ___ and supply these tissues with T3 from plasma derived T4

uLocal generation of T3 in pituitary causes __ ___ of  ___ or thyrotropin

FType 2 is __ ___by caloric restrictions so under low caloric conditions  local T3 levels in the pituitary  are ___  and no compensatoy___ in TSH levels occurs.

 

That enzyme is not affected by calorie intake

This enzyme is the one that generates T3 within the pit

Even in times of shortage of food, still make adequate T3 in the pituitary so pit doesn’t sense any change in levels of T3/T4

If pit sensed fall in T3 or T4 it will ___ TSH and that will further produce T3 and T4 ___ is ___ __ ___

By having local generation of T3 in pit, you have maintain adequate levels of TSH even in times of hunger and its not___

Deiodinase enzymes'

uType 2 found in pituitary, CNS, placenta and supply these tissues with T3 from plasma derived T4

uLocal generation of T3 in pituitary causes feedback inhibition of TSH or thyrotropin

FType 2 is not affected by caloric restrictions so under low caloric conditions  local T3 levels in the pituitary  are normal   and no compensatoy rise in TSH levels occurs.

 

That enzyme is not affected by calorie intake

This enzyme is the one that generates T3 within the pit

Even in times of shortage of food, still make adequate T3 in the pituitary so pit doesn’t sense any change in levels of T3/T4

If pit sensed fall in T3 or T4 it will secrete TSH and that will further produce T3 and T4 which are not really needed

By having local generation of T3 in pit, you have maintain adequate levels of TSH even in times of hunger and its not increased

29

Thyroid Hormone Actions

____

uThyroid hormones ____ tissue respiration: O2___  and heat___

 

___ and ___ ___

uThyroid hormones stimulate body growth and central nervous system development in well‑nourished children. 

u

 

Hyper: BMR is high...___ a lot of weight, release a lot o___t and they __ a lot

If Th is deficient at birth not supplied quickly then __ can occur and you will have __ ___

That’s why they look for this when babies are born

If given Th after brith can have catch up growth

However, if its given too late, CNS underdevelopment wont be reversed

Thyroid Hormone Actions

Respiration

uThyroid hormones increase tissue respiration: O2 consumption and heat production

Growth and CNS Development

uThyroid hormones stimulate body growth and central nervous system development in well‑nourished children. 

u

 

Hyper: BMR is high...lose a lot of weight, release a lot of heat and they sweat a lot

If Th is deficient at birth not supplied quickly then MR can occur and you will have stunted growth

That’s why they look for this when babies are born

If given Th after brith can have catch up growth

However, if its given too late, CNS underdevelopment wont be reversed

30

Thyroid Hormone Actions

Deficiency

uIodine deficiency in children leads to ____

__ ___, ___ stature, ___ in motor development, ___ hair,  ___ abdomen.

FLow levels of thyroid hormone  if discovered  shortly after birth may reverse the ___ effects but  the ___ effects are i____e if not detected  within a __ __  after birth

___ metabolism cause __ ___e, ___ sweating, ___ skin, weigh___  ___ cardiac output

u

u

Thyroid Hormone Actions

Deficiency

uIodine deficiency in children leads to cretinism

mental retardation, short stature, delay in motor

development, coarse hair,  protuberant abdomen.

FLow levels of thyroid hormone  if discovered  shortly after birth may reverse the growth effects but  the CNS effects are irreversible if not detected  within a few days after birth

uDecreased metabolism cause cold intolerance, decreased  sweating, dry skin, weight gain, low cardiac output

u

u