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A and P semester 2 > endocrine > Flashcards

endocrine Flashcards

1
Q

what is the difference between an endocrine and ex0crine gland?

A

Endocrine glands secrete into ducts

Exocrine glands secrete directly into blood/lymph

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2
Q

What are the 4 types of chemical messengers?

A

HORMONES: long distance chem signals that travel in the blood or nymph.

AUTOCRINES: local chem messengers that exert their effects on the cells that produce them.

PARACRINES: local chem messengers that effect other cells.

SECONDARY MESSENGERS: produced inside a cell and cause a response by that cell

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3
Q

What is the endocrine system’s primary goal?

A

to collaborate with the CNS to maintain homeostasis

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4
Q

What part of the brain exerts control over the endocrine system?

A

hypothalamus

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5
Q

What are the two major classes of hormones?

A

Amino acid based: vary in size from small peptides to polypeptides
-water soluble

Steroid based: synthesized from cholesterol
-not water soluble

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6
Q

Give an example of a amino acid based hormone

A

amines, thyroxine, peptides, proteins

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7
Q

Give an example of a steroid based hormone

A

gonadal, adrenocortical hormones

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8
Q

What are the 5 ways that a hormone can alter target cell activities?

A

CHANGE permeability or potential (ion channels)

STIMULATE synthesis of enzymes or other regulatory molecules

ACTIVATE/DEACTIVATE enzymes

INDUCE secretion

STIMULATE mitosis

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9
Q

What are the two mechanisms that hormones use convey their message to target cells?

A

indirect: used by amino acid hormones (water-soluble which can’t get through the phospholipid bilayer)
- involves a G protein and 2nd messenger in cell

Direct: used by lipid soluble hormones (can get through the phospholipid bilayer)
- directly act on intracellular receptors

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10
Q

Describe the indirect mechanism for hormones

A

1) hormone binds to receptor -> receptor changes shape and binds to G protein
2) G protein binds to GTP and is activated
3) Activated G protein binds to and activates adenylate cyclase
4) this enzyme converts ATP to cyclic AMP (cAMP)
5) cAMP (second messenger) riggers response of target cell via protein kinases which activate/inactivate other proteins
6) cAMP is rapidly destroyed by phosphodiesterase

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11
Q

What is meant by indirect mechanisms can have an amplifying effect?

A

one hormone can cause multiple effects within a cell

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12
Q

Describe the direct mechanism for hormone signalling using cAMP (cyclic AMP).

A
  • hormone passes through cell membrane and nuclear membrane
  • binds to receptor chaperonin complex
  • moves to DNA and binds to receptor protein on DNA
  • turns on gene and stimulates transcription to produce mRNA
  • mRNA directs protein synthesis
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13
Q

What are the 8 characteristics of hormones?

A

1) Specific
2) act like triggers; turn cells on or off
3) degree of response to hormone is variable
4) hormones can influence the number of their receptors on the target cells
5) hormones can also influence the number and affinity of receptors for other hormones
6) hormones are effective at very low concentrations and are quickly destroyed after binding to receptors
7) speed of response of target cells vary
8) duration of response of target cells vary

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14
Q

What is the average half-life of a hormone?

A

30 minutes

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15
Q

What is the one amino acid based hormone that does not use indirect mechanisms?

A

thyroid hormone

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16
Q

What are the three factors that the degree of response to a hormone depend on?

A

Concentration of hormone in the blood

Number of receptors on target cells

Affinity of receptors to the hormone

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17
Q

Explain what up and down regulation is.

A

Target cell’s receptors are influenced by hormones in one of two ways:

UP-REGULATION: develop more receptors in response to rising hormone, therefore, become more sensitive

DOWN-REGULATION: lose receptors in response to rising hormone levels to prevent over reaction

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18
Q

What is hormone permissiveness?

A

an interaction between to hormones where….

one hormone cannot act without the presence of another hormone

ex. thyroxine must be present before reproductive hormones can cause development of the reproductive organs

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19
Q

What is hormone synergism?

A

an interaction between hormones where…

two or more hormones together exert a greater effect than either one alone

ex glucagon and epinephrine each cause increased blood sugar, but together have a 150% greater increase

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20
Q

What is hormone antagonism?

A

a hormone interaction where…

two hormones have an opposite effect on target tissue

ex glucagon and insulin

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21
Q

What are the three stimuli that can cause the release of hormones?

A

HUMORAL: changing levels of some constituent of the blood directly stimulates secretion
ex. low blood sugar triggers release of glucagon

NEURAL: nerve fibers stimulate the release
ex: release of epinephrine and norepinephrine

HORMONAL: hormones trigger secretion of other hormones by endocrine glands.
ex. hypothalamic hormones stimulate anterior pit

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22
Q

What protects/houses the pituitary gland?

A

the sella turcica of the sphenoid bone

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23
Q

What is the hypophysis?

A

pituitary gland

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24
Q

What is the neurophysis?

A

the posterior pituitary and the infundibulum that descends from the hypothalamus

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25
Q

What are the two lobes of the pituitary gland?

A

anterior and posterior pituitary

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26
Q

What are the 2 hormones secreted by the posterior pituitary?

A

ADH and Oxytocin

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27
Q

What stimulates the release of hormones from the posterior pituitary?

A

nerve impulses from the hypothalamus

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28
Q

What is the nerve tract between the hypothalamus and the posterior pituitary called?

A

hypothalamic - hypohphyseal tract

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29
Q

Describe the stimulus for release, the target, and the effect of ADH.

A

Stimulus: neural and humoral (blood levels are monitored by HT)

Target: kidney tubules

Effect: inc reabsorption of water from filtrate

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30
Q

What happens with hyposecretion of ADH? What can this cause?

A

causes diabetes insipidus

  • excrete large volumes of dilute urine
  • Low BP and BV (dehydration and acute thirst)
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31
Q

What happens with hypersecretion of ADH? What can cause this?

A

decreased urine output, water retention

results in increased BV and BP

neurosurgery, trauma, or cancer cells can cause this

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32
Q

What is the effect of alcohol on ADH?

A

it inhibits the release

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33
Q

Describe the stimulus for release, the target, and the effect of oxytocin.

A

Stimulus: neural (cervical stretching, suckling

Targets and Effects: uterus (contraction, labour), breasts (milk ejaculation)

Other effects:

  • plays a role in sexual arousal for both sexes
  • in non-sexual relationships promotes nurturing and affectionate behaviour (cuddle hormone)
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34
Q

What are the hypophyseal portal veins?

A

they are a local blood circuit between the hypothalamus and the anterior pituitary.

carry releasing/inhibiting hormones from the HT to the ant pit that direct secretion

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35
Q

What are the 6 hormones that are secreted by the anterior pituitary (hypophysis)?

A

4 TROPIC hormones:

  • TSH (thyroid stimulating hormone)
  • FSH and LH
  • ACTH

2 others:

  • GH (growth hormone)
  • Prolactin
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36
Q

Are the hormones secreted by the anterior pituitary (hypophysis) direct or indirect?

A

all are indirect and uses cAMP except GH

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37
Q

Describe the stimulus for release, the target, and the effect of GH.

A

Stimulus: GNRH from HT

Target: liver, skeletal musc, bone, and cartilage

Effect:

  • causes them to release insulin like growth factors that stimulate bone and muscle growth
  • exerts anti-insulin effects; mobilizes fats, raises blood glucose by decreasing glucose uptake and encouraging glycogen breakdown (all to provide E for growth)
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38
Q

When is the most GNRH released from the HT?

A

usually greatest release during sleep, but can be effected by stress, nutrition, and sleep patterns

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39
Q

What happens in hyposecretion of GH?

A

dec long bone growth that can result in PITUITARY DWARFISM

40
Q

What does hypersecretion of GH cause?

A

in children: GIGANTISM (increased growth of longs bones)

in adults: ACROMEGALY (overgrowth of bones in face, hands and feet that are still sensitive to GH)

41
Q

Describe the stimulus for release, the target, and the effect of TSH (thyroid stimulating hormone)

A

Stimulus: TRH (thyroid releasing hormone) from the HT

Target: thyroid gland

Effect: normal development of and normal secretion from thyroid gland

42
Q

Describe the stimulus for release, the target, and the effect of ACTH.

A

Stimulus: CRH from the HT

Target: adrenal cortex

Effect: production and release of corticosteroids

** cyclic release with greatest release in early AM **

43
Q

Describe the stimulus for release, the target, and the effect of FSH and LH.

A

Stimulus: after puberty, GnRH from HT

Target: gonads

Effect:
FSH - gamete formation
LH (ISCH in males) - stimulates gonadal hormone production

in females, the two combine to regulate the menstrual cycle

44
Q

Describe the stimulus for release, the target, and the effect of prolactin

A

Stimulus: PRH from HT

target: milk ducts
effect: stimulates lactation

45
Q

Describe the structure of the thyroid gland. What are the two types of cells in the thyroid?

A

2 lobes connected by isthmus

FOLLICLE cells: produce thyroglobulin

PARAFOLLICULAR cells: produce calcitonin

46
Q

What do the lumens of the follicles in the thyroid gland do?

A

store colloid: thyroglobulin + Iodine needed to make thyroxine

47
Q

What happens in hyposecretion of PRL (prolactin)?

A

poor milk production

48
Q

What happens in hypersecretion of PRL (prolactin?

A

menses stop, inappropriate lactation, female infertility. development of breasts and impotence for males

49
Q

What are the two thyroid hormones (thyroxines)? Which one is more active?

A

T4 and T3

T3 is ten times more reactive than T4

50
Q

What two hormones are produced by the thyroid?

A

thyroxines (or thyroid hormones, specifically T4 and T3)

calcitonin

51
Q

What is the molecular structure for T4 hormone?

A

2 tyrosine molecules + 4 bound iodine atoms

52
Q

What is the molecular structure for T3 hormone?

A

2 tyrosine molecules + 3 bound iodine atoms

53
Q

Describe the steps of synthesis of thyroxines.

A

after TSH binds to receptors on follicle cells:

1) thyroglobulin produced in follicle cells and stored as colloid in lumen of follicle
2) Iodide actively transported out of blood into colloid and oxidized to I2
3) I2 added to thyroglobulin to form T1 (monoiodotyrosine) and T2
4) T1 and T2 merge to form T3 and T4 (more T4 than T3)
5) enzymes split T4 and T3 from colloid and hormones diffuse out of cells into the blood

6) bind to transport proteins in the blood and go to target cells.
- T4 and T3 both bind to target cells, T3 much more active
- most tissues have enzymes that convert T4 to T3

54
Q

Describe the stimulus for release, the target, and the effect of thyroxines.

A

Stimulus: low thyroxine levels trigger HT to release TSH

Target: almost all body tissues/cells

Effect: increases metabolism, aids normal functioning of heart, muscles, skeleton, digestive tract, reproduction, regulation of tissue growth, and development of the nervous system

55
Q

What happens when thyroxine is hyposecreted in adults?

A

MYXEDEMA: low basal metabolic rate -> feel cold, constipation, physically and mentally sluggish

GOITER: same symptoms, but thyroid also enlarges. caused by lack of dietary iodine

56
Q

What happens when thyroxine is hyposecreted in infants?

A

CRETINISM: irreversible mental and physical retardation.

however, completely preventable if detected early and treated with thyroid hormone

57
Q

What happens when thyroxine is hypersecreted?

A

HYPERTHYROIDISM: “turning up the furnace”

eyes bulge

58
Q

What is Grave’s disease?

A

an autoimmune disease where antibodies bind to receptors in the thyroid stimulating production of thyroxine.

results in hyperthyroidism

59
Q

What secretes calcitonin and what does it do?

A

thyroid gland

lowers blood calcium by inhibiting osteoclasts and stimulating osteoblasts (stimulates bone deposits)

60
Q

Where are the parathyroid glands located?

A

2 in each lobe of the thyroid gland (can have more, it varies)

61
Q

What hormone is secreted by the parathyroid glands?

A

PTH (parathyroid hormone)

62
Q

What type of cell secretes PTH?

A

parathyroid chief cells

63
Q

Describe the stimulus for release, the target, and the effect of PTH (parathyroid hormone)

A

Stimulus for secretion: humoral -> dec in blood Ca2+ detected by parathyroid hormones

Targets:

  • skeleton: stimulates osteoclasts (release of Ca by breaking down bone)
  • kidneys: inc reabsorption of Ca2+ from urine and activation of vit D
  • Digestion: vit D inc absorption of Ca from food

Effect: raises blood Ca2+

64
Q

What happens when PTH is hypersecreted?

A
  • loss of bone salts
  • bones becomes spongy
  • excess blood Ca interferes with the nervous system
  • can cause kidney stones

this is a rare condition that can be caused by a tumour

65
Q

What happens when PTH is hyposecreted?

A

low blood calcium: hyper excitability of neurons, tetany, respiratory paralysis, death if untreated

66
Q

Describe the structure of the adrenal glands.

A

2 main layers
Outer: cortex (glandular tissue), secretes steroid hormones
Inner: medulla (part of the sympathetic nervous system) secretes catcholamines

Outer cortex has three different layers that secrete different hormones

67
Q

What are the hormones secreted by the adrenal glands?

A

Outer cortex:

  • mineralcorticoids
  • glucocorticoids
  • gonadocorticoids

Inner medulla:
- catecholamines

68
Q

Describe the stimulus for secretion for mineralcorticoids.

A

HORMONAL: low BP, BV, NA, high K activates renin - angiotensin mechanism -> inc aldosterone (the primary mineralcorticoid) release

NEURAL: HT responds to stress -> secretes CRH -> ant pit releases ACTH -> adrenal cortex releases aldosterone

HUMORAL: low blood Na, high blood K can be directed by the adrenal cortex itself

69
Q

describe the effect and target of mineralcorticoids.

A

Target: kidney tubules

Effect: kidney tubules secrete K and reabsorb Na. Water follows with it -> inc BP, volume, and Na while decreasing K

70
Q

What happens with hypersecretion of mineralcorticoids?

A

can be caused by Addison’s disease, results in:

  • wt loss
  • dec blood Na and glucose
  • hypotension
  • dehydration
71
Q

Describe the inhibition of release for mineralcorticoids.

A

Occurs when BP is too high:

heart secretes ANP -> inhibits renin and aldosterone - less Na and water absorbed

72
Q

What is alderstonism?

A

hypersecretion of mineralcorticoids:

  • excess Na and Water retention
  • inc BP and edema
  • loss of blood K
  • neurons non-functional -> muscle weakness -> paralysis
73
Q

Describe the stimulus for release and the effect of glucocorticoids.

A

Stimulus: HT releases CRH -> ant pit releases ACTH -> adrenal cortex secretes glucocorticoids

Effect: helps resist stressors.

Stimulates gluceogenesis - proteins and fats converted to glucose or catabolized for E.

74
Q

What happens if glucocorticoid levels are elevated for too long? (hyper secretion)

A

reduced inflammatory and immune responses

Could be Cushings’s syndrome/disease: moon face

syndrome caused by adrenal tumour
disease caused by pit tumour

75
Q

What happens when glucocorticoids are hyposecreted?

A

can be caused by Addison’s disease

  • dec blood glucose, and Na
  • wt loss
  • severe dehydration and hypotension
  • hypoglycemia
76
Q

What are gonadotropins?

A

most are androgens converted to either testosterone or estrogens

  • role not well known
  • may contribute to onset of puberty and development of secondary sex characteristics
  • in woman, androgens may cause sex drive and then be converted to estrogens after menopause
77
Q

What happens in hypersecretion of gonadocorticoids?

A

masculinization of females or prepubertal males

78
Q

What is the type of cell in the adrenal medulla? What do they secrete?

A

CHROMAFFIN cells: secrete 80% epinephrine, 20% epinephrine

these are Catcholamines

79
Q

What do catcholamines do? (epinephrine and norepinephrine)

A

reinforce effects of the sympathetic nervous system in fight or flight response

  • inc HR, BP, blood sugar, peripheral vasoconstriction, etc
80
Q

What happens in hyposecretion and hypersecretion of catcholamines?

A

hyposecretion is not a problem since sympathetic nervous system can make up the difference

Hypersecretion is very rare - effects are like massive uncontrolled sympathetic nervous stimulation

  • hyperglycemia
  • high BMR
  • rapid HBR
  • hypertension
81
Q

describe the structure of the pancreas and the function of each aspect

A

it is both a exocrine (digestion) and endocrine gland

Islets of Langerhans contain endocrine cells:

  • alpha cells produce GLUCAGON
  • beta cells produce INSULIN
82
Q

What do glucagon and insulin do together?

A

regulate blood glucose level

they are antagonistic to each other

83
Q

Describe the stimulus for release, the target, and the effect of glycagon

A

stimulus: drop in blood glucose

Target: Liver

Effects:
GLYCOGENOLYSIS - conversion of glycogen to glucose, release of glucose into the blood
GLUCOGENESIS - conversion of lactic acid, fats and proteins to glucose

results in raising blood glucose

84
Q

What results from hyposecretion of glucagon?

A

chronic hypoglycemic conditions

85
Q

Describe the stimulus for release, the target, and the effect of insulin.

A

Stimulus: inc blood sugar

Targets:

  • LIVER - stims storage of glucose by converting it to glycogen
  • MUSCLE and FAT cells take up glucose
  • inhibits gluconeogenesis

Effect: lowers blood glucose

86
Q

What happens in hyposecretion of insulin?

A

can be caused by diabetes mellitus
symptoms: polyuria, polydipsia, polyphagia

glucose can’t enter cells without insulin, therefore dec fuel for ATP production resulting in more glucose being released, but with no effect
- inc release of glucose -> inc blood glucose -> glucose lost in urine and pulls water with it

more fats mobilized -> inc fatty acids in blood -> ketone bodies (organic acids) -> acidosis and ketouria -> if untreated leads to coma and death

87
Q

What happens when insulin is hypersecreted?

A

hypoglycemia -> less glucose to brain -> convlusions -> unconsciousness -> death if untreated

88
Q

What does the pineal gland secrete?

A

MELATONIN: may affect

  • timing of sexual maturation and puberty
  • day and night cycles
  • circadian rhythms of body
89
Q

What do the ovaries secrete? What do these hormones do?

A

Ovaries: ESTROGENS & PROGESTERONE

  • stimulate normal growth/maturation of reproductive system and development of secondary sex characteristics
  • together control menstrual (uterine and ovarian) cycle
90
Q

What do the testes secrete? What does this hormone do?

A

Testosterone:

  • normal growth and development of reproductive system, development of secondary sex characteristics
  • spermatogenesis
  • sex drive
91
Q

What does the placenta secrete during pregnancy?

A

estrogens, progesterone, and human chorionic gonadotropin (HCG) which act on uterus to influence pregnancy

92
Q

What does the thymus secrete? what do these do?

A

Thmopoietin, thymic factor and thymosin

  • assist development of T lymphocytes to become immunocompetent
93
Q

What are enteroendocrine cells and what do they do?

A

They are cells in the mucosal lining of the digestive tract that secrete local hormones that control activities of digestion

some examples of hormones:
gastrin, CCK, secretin

94
Q

What do the kidneys secrete? what does this do?

A

ERYTHROPOIETIN in response to low blood 02

target is red bone marrow, stims RBC prod.

95
Q

What hormone does the skin secrete? what does this do?

A

CHOLECALCIFEROL:

inactive precursor of vit D - activated in liver and kidney

96
Q

What hormone does the adipose tissue secrete? what does this do?

A

LEPTIN:
secreted after uptake of glucose and lipids

target is CNS neurons - gives feeling of satiety

also produces resistin (an antagonist of insulin)

97
Q

What are three developmental aspects of hormones?

A

1) hormone function can be disrupted by environmental exposures to things like pesticides, industrial chems…. etc
2) Pollutants effect: sex hormones, thyroid hormone, and glucocorticoids
3) high cancer rates in certain areas may be due to interference with glucocorticoids

A and P semester 2 (10 decks)

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