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PR3152 > ANAT > Flashcards

ANAT Flashcards

1
Q

definition of hormone

A
  1. Are substances released by endocrine glands and transported throughout the blood stream to target tissues where they act to regulate specific functions
  2. Need to travel to distal sites via blood
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2
Q

difference between endocrine glands and exocrine glands

A
  1. endocrine produces small amount of hormones while exocrine produce nonhormonal substances
  2. endocrine does not have duct; exocrine have duct
  3. endocrine release hormones straight into the surrounding tissue fluid and into the blood; exocrine release into duct that carry these substances to a membrane surface
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3
Q

difference between endocrine system and nervous system

A
  1. endocrine system slow acting hormone messengers; nervous system fast acting electrochemical impulses delivered by neurons
  2. long term slow response; short term quick response
  3. release hormone; release neurotransmitters
  4. regulates activities that require duration (overtime) rather than speed such as growth, development, reproduction to maintain homeostasis; regulates activity of muscles and glands (immediate)
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4
Q

list the types of endocrine glands

A

hypothalamus, pituitary, thyroid, gonads, pancreas

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5
Q

types of secondary endocrine organs

A

kidney, heart, stomach, small intestine, skeleton, skin, adipose tissue, placenta

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6
Q

name the 2 classification of hormones

A
  1. based on endocrine gland that produced it
  2. based on chemical nature of hormones
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7
Q

name the 3 building blocks of hormones

A

proteins and peptides (amino acids), steroids (cholesterol derivative), amines (tryptophan or tyrosine amino acids)

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8
Q

name the hydrophilic and hydrophobic hormones

A

hydrophilic: FSH, LH, TSH, insulin, glucagon, inhibin, HCG, calcitonin, PTH, oxytocin
hydrophobic: testosterone, progesterone, estrogen/estradiol, vitamin D (calcitriol), melatonin, T3, T4

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9
Q

how are hydrophilic and hydrophobic hormones transported around the body?

A

hydrophilic: dissolved and transported free in blood
hydrophobic: bound to plasma proteins

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10
Q

why are not all the surrounding tissues responsive to the hormone that is being released into the bloodstream?

A

because the target cells have receptors only for that hormone. hormone actions are mediated by binding of hormone to receptor molecules on target tissues specific to that hormones

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11
Q

types of target receptor and types of hormones they bind to + rationale

A
  1. Cell membrane receptors
    - protein
    - catecholamines
    *They are both water soluble, hydrophilic hormones. They bind to cell surface receptors because they cannot enter the lipophilic cell membrane
  2. Intracellular receptors
    - steroid hormones
    - thyroid hormones
    *They are both lipid soluble, hydrophobic hormones, which can enter the cell membrane due to its hydrophobic nature.
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12
Q

binding of hormone with the receptor triggers:

A
  1. alters channel permeability by acting on pre-existing channel-forming proteins
  2. acts through second-messenger system to alter activity of pre-existing proteins
  3. activates specific genes to cause formation of new proteins
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13
Q

is high or low amount of hormones required by the body? why?

A

low. due to signal amplification, tyrosine kinase phosphorylation due to one protein getting phosphorylated and this triggers another protein to get phosphorylated as well

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14
Q

how does our body regulate fluctuations in hormone levels?

A

negative feedback loop - inhibition of the previous stimuli

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15
Q

HPA stands for

A

hypothalamic-pituitary axis

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16
Q

where is thyroid gland located?

A

in the neck,
on the anterior surface of trachea,
immediately below the larynx

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17
Q

shape of thyroid glands

A

two lobes connected by isthmus

18
Q

is thyroid gland an endocrine or exocrine gland ? why does thyroid gland have an extensive blood supply?

A

endocrine. require blood to transport hormone around the body

19
Q

list the types of cells in thyroid gland + function

A
  1. follicle cells: Lines around the follicles , Synthesize a globular protein called thyroglobulin and secrete it into the colloid of the thyroid follicles. Thyroglobulin is the backbone of hormone
  2. and parafollicular cells (C cells): Cells in between the follicles, Secrete calcitonin and Regulate calcium homeostasis
20
Q

2 other microscopic structures in thyroid glands + function

A

thyroid follicles (Functional unit for thyroid hormone production & Consists of follicle cells and colloid) and colloid (Extracellular space where thyroglobulin with attached iodine atoms are stored, T3, T4 stored)

21
Q

2 ingredients for thyroid hormones synthesis

A

tyrosine (synthesised in body) + iodine (dietary intake which must be reduced to iodide ion for it to be absorbed by small intestine)

22
Q

where do most steps of thyroid hormone synthesis occur in?

A

on TG molecules within the colloid

23
Q

name the 5 steps of thyroid hormone synthesis

A

iodine trapping, iodination, coupling, colloid resorption, thyroglobulin proteolysis

24
Q

recall the 15 steps of thyroid hormone synthesis

A

refer to onenote/slides

25
Q

which is the inactive thyroid hormone, T3 or T4? highest concentration in plasma; 90% of secretory produce released from thyroid gland

A

T4; T3 is the major biologically active form of TH at the cellular level (10 times more potent than T4) –> T3 gets preferentially binding to receptors

26
Q

where does T4 get converted into T3 and via which enzyme?

A

liver, kidney and pituitary; 5-deiodinase enzyme

27
Q

method of excretion of inactive metabolites formed during conversion of T4 to T3?

A

secreted into bile and eliminated in the feces with trace amount in the urine

28
Q

conversion of inactive metabolite does not occur in which organ?

A

pituitary

29
Q

how many percentage of T3 is derived from secreted T4?

A

80%

30
Q

T4 and to a lesser extent T3, are also metabolised in the liver. what is the process called and with what compound?

A

metabolised by conjugation with glucuronic acid in the liver

30
Q

T4 and to a lesser extent T3, are also metabolised in the liver. what is the process called and with what compound?

A

metabolised by conjugation with glucuronic acid in the liver

31
Q

TRH stands for
TSH stands for

A

thyrotropin releasing hormone
thyroid stimulating hormone

32
Q

T4, T3 physiological effects (6 effects)

A
  1. increase basal metabolism rate (increase ventilation, HR, increase heat production (calorigenic effect)) - increase size and number of mitochondria together with increase in enzymes that regulates oxidative phosphorylation
  2. sympathomimetic effect
  3. cardiovascular effects
  4. essential for bone growth and maturation
  5. crucial for development of nervous system, especially the brain during childhood
  6. increase synthesis and degradation of proteins, lipids, and carbohydrates
33
Q

hypothyroidism 3 causes

A
  1. primary failure of thyroid gland
  2. secondary to deficiency of TRH, TSH or both
  3. inadequate dietary supply of iodine
34
Q

hyperthyroidism 3 causes

A
  1. production of TSI
  2. secondary to excess of TRH, TSH or both
  3. hypersecreting thyroid tumour
35
Q

signs and symptoms of hyperthyroidism (8)

A

intolerance to heat, weight loss, muscle wasting, increase systolic BP, tremors, increased diarrhea, bulging eyes, enlarged thyroid

36
Q

signs and symptoms of hypothyroidism (7)

A

intolerance to cold, brittle nails and hair, weight gain, constipation, fatigue, cardiac complications, dull-blank expression

37
Q

describe graves diseases and the mechanism behind this

A

is an autoimmune disease in which the body erronously produces TSI (thyroid stimulating immunoglobulin) which mimics the action of TSH. they are able to bind to the TSH receptors on the thyroid cells which stimulates the production of T3 and T4. this cannot be controlled by negative feedback because TSI is not affected by subjected to negative feedback loop.

38
Q

does graves disease patients have goiter?

A

yes

39
Q

what is a goiter and what are the causes?

A

goiter = enlarged thyroid gland
caused by increased levels of TSH and TSI

can be caused by hypothyroidism due to lack of iodine intake from diet which causes increased TSH due to negative feedback

hyperthyroidism which is graves disease that produces TSI that activates TSI-TSH receptors

40
Q

treatment of graves disease (3)

A
  1. anti-thyroid medications that interferes with the synthesis of TH (carbimazol spofa) - prevent iodine absorption or deactivating TPO (thyroperoxidase)
  2. surgically remove a portion of the enlarged thyroid gland - risk of hypothyroidism
  3. administer radioactive iodine - to destroy thyroid gland

PR3152 (7 decks)

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