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Human Physiology > Lecture 22 > Flashcards

Lecture 22 Flashcards

1
Q

The thyroid gland is located in the ________ and consists of:

_______, ______, and _______

A

anterior neck
- right and left lobes
- isthmus
- fibrous capsule

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2
Q

the right and left lobes are located anterolateral to the _____ and _____

A

larynx and trachea

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3
Q

the isthmus is located ______

A

over the trachea and unites the lobes

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4
Q

the fibrous capsule is located where ?

A

surrounds the thyroid gland and sends septa deep into the gland

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5
Q

the fibrous capsule is located where ?

A

surrounds the thyroid gland and sends septa deep into the gland

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6
Q

The thyroid gland has a blood flow about ___x the weight of the gland each minute

A

5x

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7
Q

the thyroid gland contains microscopic spherical sacs called _________

A

thyroid follicles

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8
Q

the wall of each thyroid follicle consists of primarily _________ cells called _________.

A

cuboidal epithelial cells
follicular cells

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9
Q

follicular cells extend into the _______ of each follicle

A

luminal space

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10
Q

Follicular cells secrete a product called _____ which fills the follicle lumen.

A

colloid

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11
Q

Colloid is mainly comprised of a large glycoprotein called ________ which contains the thyroid hormones ________ within its molecule

This secretory product must be absorbed back through the _______ and then into the blood before it can function in the body.

A

thyroglobulin
(T3 and T4)

follicular epithelium

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12
Q

Thyroid hormone T4 is _________
T3 is ___________

A

Thyroxine (tetraiodothyronine or T4 )
Triiodothyronine (T3 )

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13
Q

Thyroxine (tetraiodothyronine or T4 )- contains _____ atoms of _____
Triiodothyronine (T3 )- contains ___ atoms of ____

___% of the hormone secreted by the thyroid gland is thyroxine.
___% of the hormone secreted by the thyroid gland is triiodothyronine.

A

4
iodine

3
iodine

93%
7%

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14
Q

____ is 4x as potent as ___ but is present in the blood at much ______ quantities and persists for a much ______ time.

A

T3
T4
smaller
shorter

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15
Q

Most ingested iodides are absorbed by the GI tract and rapidly excreted by the ______

However, about____% of our ingested iodide is removed from the circulating blood by the thyroid gland.

Iodide is then used for the synthesis of thyroid hormone.

A

kidneys

20%

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16
Q

Iodide is added to table salt at ______ Sodium Iodide per ______ of Sodium Chloride

A

one part
100,000

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17
Q

Iodine requirement by the body: ____ MG PER YEAR

If there is no iodine to allow production of thyroxine and triiodothyronine, the anterior pituitary continues to sense this, and ramps up______ production.

This stimulates the thyroid further, and the follicular cells _____________.
Overall, the thyroid gland may become ________ than normal

A

50 mg/year

TSH

grow larger and larger
10-20x larger

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18
Q

___________:
- thyroid follicular cells trap iodide ions by ________ transporting (pumping) them from the blood into the cytosol.

A

Iodide Trapping
actively

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19
Q

second step is the Synthesis of_________:
- Occurs while iodide is being trapped
- Follicular cells synthesize a large glycoprotein called _________ in the ___ and _______.
- It is packaged into secretory vesicles that will undergo exocytosis.
- Exocytosis will release it into the__________

A

thyroglobulin
thyroglobulin
ER
golgi complex
lumen of the follicle

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20
Q

step three is ________ of Iodide:
- __________ amino acids in thyroglobulin will become iodinated.

  • Once iodide is oxidized by enzyme_________, it passes through the membrane into the _________.
A

Oxidation
tyrosine
thyroid peroxidase (TPO)
lumen of the follicle

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21
Q

step four is ___________:

  • Newly formed _______ react with the _____ that are part of the thyroglobulin molecules.
  • Binding of one iodine atom to tyrosine yields ___________ and binding of two yields __________
  • The thyroglobulin accumulates in the follicle lumen
A

Iodination of Tyrosine

iodine
tyrosines

monoiodotyrosine (T1)
diiodotyrosine (T2 )

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22
Q

step five is Coupling of________ :
-_____ _____ molecules combine to form _____
- ____ ___ molecule and ____ ____ molecule combine to form ___

A

T1 and T2

two T2
T4

One T2
one T1
T3

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23
Q

Transport occurs upon stimulation of the thyroid gland by _____

Step 6
- when stimulated, droplets of _______ reenter follicular cells by _______ and merge with _______.

  • Digestive enzymes in the lysosomes breakdown _________, cleaving off molecules of ______.
A

TSH

colloid
pinocytosis
lysosomes

thyroglobulin
T3 and T4

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24
Q

Step 7.) ________ of Thyroid Hormone:

  • ______-soluble T3 and T4 diffuse through the plasma membrane into the _____ and then into the ____.
  • In the blood more than 99% of both T3 and T4 combine with __________ within the blood mainly ________
A

Secretion

lipid
ISF
blood

transport proteins
thyroxine-binding globulin (TBG)

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25
Q

Diffusion of thyroid hormone:

Once T3 and T4 arrive at the target body cells these lipid-soluble hormones can readily diffuse across the membrane.

It is important to note that although ____ is secreted in higher quantities, once it arrives at the target cells an enzyme called an_______ directly converts it to ____ which is the thyroid hormone that acts within the target cell.

Intracellular hormone receptors have a high affinity for ____specifically.

A

T4
iodinase
T3

T3

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26
Q

Intracellular receptor binding:

_____ binds to an intracellular receptor forming a ___________

This complex activates __________ which results in the production of new ____

A

T3
thyroid hormone-receptor complex

gene transcription
mRNA

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27
Q

Synthesis of new protein:

______ diffuses from the nucleus into the cytosol where it attaches to _______.

________ translate the mRNA into _______
This produces the thyroid hormone response of the cell

A

mRNA
ribosomes

Ribosomes
new protein

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28
Q

_____ blood levels of T3 and T4 , _____ metabolic rate, and exposure to ____ temperatures stimulate the hypothalamus to secrete thyrotropin-releasing hormone (TRH).

A

Low
low
cold

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29
Q

TRH enters the __________ and flows to the anterior pituitary where it stimulates _________ to secrete ________

A

hypophyseal portal system
thyrotrophs
thyroid-stimulating hormone (TSH).

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30
Q

TSH travels through the bloodstream to the thyroid gland where it stimulates nearly all aspects of thyroid _______ such as: iodide trapping, hormone synthesis and secretion and even growth of the follicular cells.

A

follicular cell activity

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31
Q

Thyroid follicular cells release T3 and T4 into the blood until either the:
- _________ returns to normal or
- ___________ returns to normal

A

metabolic rate
body temperature

32
Q

Elevated _____ in the body fluids feeds back to the hypothalamus and pituitary gland ________ the release of TRH and TSH respectively.

This negative feedback occurs when the rate of thyroid secretion rises to about _____ x normal.
Secretion of thyroid hormone is then stopped

A

T3
inhibiting

1.75x

33
Q

Thyroid Hormone Stimulates __________ Metabolism: Increases circulating glucose for ATP production

- Increases rapid uptake of glucose into cells
- Increases glycogenolysis
- enhances glycolysis and gluconeogenesis
- increases carb absorption in GI tract
- increased insulin secretion
A

Carbohydrate

34
Q

Thyroid Stimulation of Fat Metabolism:

  • Increase in ________- releasing _______ which can be used for ATP production
A

lipolysis
free fatty acids

35
Q

Effect of thyroid hormone on Plasma and Liver Fats:

  • _________ the concentration of cholesterol, phospholipids and triglycerides in the plasma, it _________ free fatty acids
  • decreased thyroid secretion results in ________ in plasma concentrations of cholesterol, phospholipids and triglycerides and almost always causes excessive deposition of fat in the liver.
A

Decreases
increases

increases

36
Q

thyroid results in ________ Basal Metabolic Rate:

  • Thyroid hormones _______ the rate of oxygen consumption under standard or basal conditions (awake, at rest, and fasting).
A

Increased
increase

37
Q

thyroid hormone result in______ Respiration, Blood flow, and Cardiac Output:
- Increased BMR causes increases in oxygen consumption and formation of carbon dioxide.
- These increases activate the brainstem to______the rate and depth of respiration, as well as stimulating vasodilation in most body tissues which increases blood flow.

A

Increased
increase

38
Q

Thyroid hormones stimulate the synthesis of additional _____ pumps

- These pumps use large amounts of ATP to move Na and K across the membrane against the gradients

- As the cells produce and use more ATP, heat is given off and the body temperature rises. This is known as the \_\_\_\_\_\_\_\_ effect
A

Na/K
calorigenic

39
Q

Thyroid hormones enhance some actions of _________ because they upregulate ______ receptors

  • This causes ________ in heart rate and blood pressure
A

catecholamines (epinephrine and norepinephrine)
beta

increases

40
Q

thyroid hormone results in ________ of the CNS:
- Due to upregulation of beta receptors, thyroid hormone increases mentation.
- Individuals with hyperthyroidism thus have bouts of extreme nervousness, psychoneurotic tendencies such as anxiety complexes, extreme worry, and paranoia.

A

Excitation

41
Q

thyroid hormones ______ the muscular system

Therefore, hypothyroidism causes muscles to become _______ where hyperthyroidism causes _______

A

excite
sluggish
fine muscle tremors.

42
Q

thyroid hormone Increases _________gland secretion:

- Thyroid hormones act on oil and sweat gland cells to increase their secretory activity produces increased perspiration and oily skin.

- Individuals with \_\_\_\_\_\_\_\_\_\_ often complain of lack of sweating, dry skin, and dry hair.
A

suderiferous and sebaceous
hypothyroidism

43
Q

due to the exhausting effects of thyroid hormone on the CNS and muscles, the ________ individual is often tired but cannot suppress the excitable effects of the hormone which often results in insomnia.

A

hyperthyroid

44
Q

Males: _____ of thyroid hormone causes loss of libido and excessive hormone sometimes causes _____

Females:____ of thyroid hormone causes _______ and loss of _____

A

lack
impotence

lack
oligo- and amenorrhea
libido

45
Q

we have ___ adrenal (or _______ glands)
At ______ poles of the ______

A

2
suprarenal

superior
kidneys

46
Q

two distinct parts of adrenal glands ?

A

Adrenal Cortex (outer)
Adrenal medulla (center)

47
Q

Adrenal Cortex:
-outer ___% of gland
- divided into ___ distinct zone
-secretes a group of hormones called ________ synthesized from _______.
- each zone secretes a different type of hormone

A

80%
3
corticosteroids- steroid hormones
cholesterol

48
Q

Adrenal medulla-
- central ____% of the gland
-functionally related to the ______ nervous system
- secretes the hormones __________ and _______

A

20
sympathetic
epinephrine and norepinephrine

49
Q

adrenal cortex is subdivided into ____ zones

what are they?

A

3

zona glomerulosa (outermost)
Zona faciculata (middle)
Zona reticularis (inner)

50
Q

Zona glomerulosa:
- outermost ____% of adrenal cortex, just ______ the connective tissue capsule
- cells contain enzyme ________
- secrete hormones called ________ which effect mineral homeostasis
-_______!

A

15%
beneath
aldosterone synthase
mineralocorticoids
aldosterone

51
Q

what zone is the widest?

A

Zona faciculata

52
Q

Zona faciculata
______% of adrenal cortex
- secrete mainly ___________ which affect glucose homeostasis
-secretion controlled by the hypothalamic-pituitary axis secretion of ______________
-_________!

A

75%
glucocorticoids
adrenocorticotropic hormone (ACTH)
cortisol

53
Q

Zona reticularis:
- synthesize small amounts of _______-
- secretion controlled by the hypothalamic-pituitary axis secretion of __________and _______________

-e.g. ____________

A

weak androgens
adrenocorticotropic hormone (ACTH)
cortical androgen-stimulating hormone

dehydroepiandrosterone (DHEA)

53
Q

Adrenocortical hormones are derived from _______

Cells of the adrenal cortex can form small amounts of ______ from ______

However, about ____% of the cholesterol used for ______ is derived from __________ in circulating plasma.

A

cholesterol
cholesterol
acetate

80%
steroid synthesis
low-density lipoproteins (LDLs)

54
Q

How are LDLs Captured and Used:

LDLs diffuse from the plasma into the ____ and attach to specific receptors contained in ______ on the _______ cell membrane.

Coated pits are internalized by ________, forming vesicles that will fuse with cell lysosomes
_________ is released to make steroid hormones

A

ISF
coated pits
adrenocortical

endocytosis
Cholesterol

55
Q

______ cell uptake of cholesterol is regulated
This regulation can alter the amount of cholesterol available for _____ synthesis
One of the main regulators is the secretion of ____

A

Adrenal
steroid
ACTH

56
Q

Once cholesterol enters the cells it is delivered to the _________ where cholesterol is ______

This results in the formation of _________
this is the rate-limiting step in the eventual formation of ________

A

mitochondria
cleaved
pregnenolone
adrenal steroids

57
Q

Produced by cells of the zona glomerulosa

A

Mineralocorticoids

58
Q

Mineralocorticoid produce mainly _______

A

aldosterone

59
Q

Physiological Action of Aldosterone:

Regulates homeostasis of mineral ions ________, and helps adjust ____________

Also promotes excretion of ____ in the urine.
- This removal of acid from the body can help prevent acidosis

A

Na+ and K+
blood pressure and blood volume

H+

60
Q

Produced by cells of the zona faciculata

A

Glucocorticoids

61
Q

Glucocorticoids mainly produce __________

A

cortisol (95%), cortisone, and corticosterone

62
Q

Physiological Action of Glucocorticoids

A

Regulates the metabolism and resistance to stress

63
Q

The extra glucose supplied by the liver cells provides tissues with a ready source of ATP
- ATP helps fight many _______ such as: exercise, fasting, fright, extremes of temp., High altitude, bleeding, infection, surgery, trauma, and disease.
- In addition, because ________ make blood vessels more sensitive to other hormones that cause _________, they are said to raise ___________.

How would this be Advantageous?
- _____________________________

A

stresses
glucocorticoids
vasocontriction
blood pressure

In severe trauma and blood loss, this helps raise blood pressure.

64
Q

Effects of Glucocorticoids on Stress:

  1. Anti-inflammatory Effects:
    • glucocorticoids inhibit the activity of ______ that participate in inflammatory responses.
    • Unfortunately, they also _____ tissue repair and wound healing.
    • In low or short-term doses, glucocorticoids have proven very effective in treating chronic inflammatory disorders such as rheumatoid arthritis.
  2. Immune Responses:
    • proven to ______ the surveillance and response of the immune system
    • Often prescribed for __________ to counter tissue rejection.
A

WBCs
slow
depress
organ transplant recipients

65
Q

Secreted by zona reticularis

A

Androgens, mainly DHEA

66
Q

Physiological effects of Adrenal androgens

Secretion of adrenal androgens is so low that is has little physiologic effects, especially in males.

Males:
-mainly stimulate the growth of _________, as well as the prepubertal growth spurt in boys (and girls)

Females:
promote_____, and are converted into _____ by other body tissues
After menopause, when ovarian secretion of estrogen ceases, all estrogens come from the conversion of _________

A

axillary and pubic hair

libido
estrogens
adrenal androgens

67
Q

Hormone producing cells of the adrenal medulla

A

Chromaffin Cells

68
Q

The sympathetic nervous system exerts direct control over the chromaffin cells, and hormone release can occur ______

A

quickly

69
Q

released by Chromaffin cells is ________
these are ____________

Metabolites of catecholamines are called ___________

A

Catecholamines

Epinephrine
Norepinephrine

metanephrines

70
Q

____% of the medullary cells secrete epinephrine
____% secrete norepinephrine

Physiological Action:
- ____________________

A

80%
20%

Intensify sympathetic Fight or Flight response

71
Q

Constricts most blood vessels in the body (increased arterial pressure)
Increases activity of the heart
Increased muscle strength
Increased blood glucose concentration
Increased glycolysis in liver and muscle
Increased mental activity
Increased coagulability
Dilates pupils
Inhibits kidneys
Inhibits GI tract

A

norepinephrine

72
Q

Constricts most blood vessels in the body (increased arterial pressure)
Increases activity of the heart
Increased muscle strength
Increased blood glucose concentration
Increased glycolysis in liver and muscle
Increased mental activity
Increased coagulability
Dilates pupils
Inhibits kidneys
Inhibits GI tract

A

epinephrine

73
Q

________ has greater Beta Adrenergic receptor stimulation, meaning:
- Greater cardiac stimulation means more cardiac output increase

_____________ has far greater effect on blood vessels of the muscles
- This increases total peripheral resistance and arterial pressure increases, but less of a direct effect on cardiac output

A

Epinephrine

Norepinephrine

74
Q

Together, the effects norepinephrine and epinephrine look like _______________ activation

These effects last longer (hormones rather than direct nervous system activation).

Epi and Norepi effects last from _______ after the stimulating event

A relatively small percentage of cells in the body have direct sympathetic innervation
Despite this, all cells have a ________ increase caused by epinephrine, and to some extent norepi.

A

sympathetic (fight or flight response)

2-4 minutes
metabolic rate

Human Physiology (24 decks)

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