Structures & Function of Endocrine System Flashcards

1
Q

Hypothalamic-Pituitary Axis (HPA)

A

critical signaling pathway for the endocrone system

anterior pituitary and posterior pituitary

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2
Q

Anterior Pituitary

A

releases pituitary releasing hormones, that descend through hypophyseal portal system

most hormones of hypothalamus communicate w/pituitary, some hormones of hypothalamus release inhibit release of pituitary hormones

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3
Q

Hypophyseal Portal System

A

capillaries in hypothalamus communicate with pituitary capillaries before entering venous system

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4
Q

Posterior Pituitary

A

hypothalmic nuclei synthesize pituitary hromones

hormones: ADH and oxytocin

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5
Q

Hypothalamus

A

links CNS to endocrine
located in diencephalon
nuclei in control release hormones from pituitary gland

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6
Q

TRH (thyrotropin releasing hormone)

A

stimulates release from TSH (thyroid stimulating hormone)

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7
Q

GnRH (gonadotropin releasing hormone)

A

Stimulates release of:
LH (luteinizing hormone) from anterior pituitary
FSH (follicle stimulating hormone) from anterior pituitary

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8
Q

Somatostatin (SRIF somatotropin release inhibiting factor)

A

GH (somatotropin) from anterior pituitary

TSH (thyroid stimulating hormone) from anterior pituitary

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9
Q

GHRH (growth hormone releasing hormone)

A

stimulates release of GH from anterior pituitary

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10
Q

CRH (corticotropin releasing hormone)

A

Stimulates release of
ACTH (adrenocorticotropic hormone) from anterior pituitary

B-endorphin from anterior pituitary

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11
Q

Substance P

A

INHIBITS synth of: ACTH (adrenocorticotropic hormone) from anterior pituitary

STIMULATES release of: GH, FSH, LH and prolactin

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12
Q

Dopamine (PIF- prolactin inhibiting factor)

A

inhibits synthesis release of prolactin from anterior pituitary

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13
Q

PRF (prolactin releasing factor)

A

stimulates release of prolactin from anterior pituitary

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14
Q

Hormones released from hypothalamus that control anterior pituitary

A

TRH, GnRH, Somatostatin, GHRH, CRH, Substance-P, Dopamine, PRF

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15
Q

Hormones synthesized in nuclei of hypothalamus and descend to posterior pituitary gland

A

ADH, Oxytocin

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16
Q

Pituitary (anterior/posterion) function

A

regulates the activity of most endocrine glands in the body

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17
Q

Function of Oxytocin

A

females-milk ejection, uterine contraction

Males–sperm motility

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18
Q

Target Tissue of Oxytocin

A

mammary glands (lactating), uturus during pregnancy

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19
Q

Stimulus for Oxytocin Release

A

distention of cervix at end of pregnancy, breast stimulation, positive emotional responses, positive feedback cycle of oxytocin (releases more release)

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20
Q

Inhibition of Oxytocin Release

A

external stimulus stops, “negative” emotional factors (stress, fear, noise, pain)

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21
Q

Function of ADH

A

control osmolality/osmolarity of plasma which influences blood volume.
ADH will increase blood volume (decreasing osmolarity, increasing blood pressure)

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22
Q

Target Tissue of ADH

A

collecting ducts in kidneys (increases water re absorption by increasing permeability of collecting ducts)
has an affect on vascular smooth muscle (blood vessel contraction to assist in elevating BP)

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23
Q

Stimulus of Release of ADH

A

increased plasma osmolarity stimulate ADH release (osmoreceptors in hypothalmamus detect increases of plasma osmolarity)

Decreased blood volume stimulate ADH release

Angiotension II indirectly promote ADH release

Additional Stimuli for ADH release(stress, truama, exercise)

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24
Q

Inhibition of ADH Release

A

decreased plasma osmolarity (detected by osmoreceptors)
increased blood volume/pressure (detected by mechanoreceptors in atria, aortic arch and carotid sinus)
Alcohol and caffeine

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25
Q

Syndrome of Inappropriate ADH secretion (SIADH)

A

elevated ADH secretions results in excessive water re absorption in kidney

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26
Q

Hypervolemia

A

excessive ADh release causes water re absorption in DCT/collecting duct.
Hypervolemia facilitates hyponatremia and natriuresis

27
Q

Hyponatremia

A

decreased sodium values in blood stream\increased EFC inhibits RAAS (renin/angio/aldosterone)

28
Q

Natriuresis

A

Excessive sodium excretion
expansion of EFC reduces sodium resorption on kidney
baro receptors reduce sodium resorption
decreased aldosterone releases which reduces sodium resorption in kidney

29
Q

Anterior Pituitary Hormones

A

hormone release is regulated by hypothalamic-hypophyseal portal system
Releases 6 hormones
prolactin, GH, TSH, GnRH (LH, FSH), ACTH, MSH

30
Q

Prolactin Function

A

breast development, stimulates milk production, inhibitions ovulation

31
Q

Target Tissues of Prolactin

A

mammary glands

32
Q

Stimulus of prolactin release in puberty

A

presence of elevated growth hormone, estrogen, progesterone, thyroid releasing hormone

33
Q

Stimulus of Prolactin release in Pregnancy

A

combined presence of elevated estrogen and progesterone stimulate release of prolactin (duct development)

34
Q

Stimulus of Prolactin release in Lactation

A

physcial action of breast feeding stimulates release of prolactin

35
Q

Inhibition of prolactin release

A

constant tonic release of dopamine
elevated levels of prolactin will stimulate the hypothalamus to increase tonic release dopamine

dopamine agonists

36
Q

GH-Growth hormone

A

released in pulsing/cyclic pattern

37
Q

Functions of GH (and IGF-1)

A

stimulates tissue growth and mturation
Gh works with IGF-1, promotes growth of tissue and regulates metabolism to facilitate growthalso has role in aging, sleep, reproductive hormone function

38
Q

Target Tissue of GH

A

Direct effect on tissues via GH reveptors: liver, muscle adipose

Indirect via IGF-1
GH stimulates liver which produces IGF-1

39
Q

Target Tissue of IGF-1

A

bone, cartilage, visceral organs

40
Q

Actions of GH on liver

A

anabolic action

IGF synthesis, protein synthesis

41
Q

Actions of GH on Adipose tissue

A

increased lypolysis, decrease glucose uptake

42
Q

Actions of GH on Muscle

A

increase amino acid uptake/protein synthesis, decrease glucose up take (mobilize/maintain glucose for blood stream)

43
Q

Actions of IGF-1 on Cartilage

A

stimulates cartilage matric growth/balance, increase/maintain tissue growth, increase synthesis of matrix, amino acid uptake, protein synth (DNA/RNA synth), critical for linear bone growth

44
Q

Actions of IGF-1 on Muscle, bone, organs

A

Amino acid uptake/protein synth (DNA/RNA synth)
increased cell size/number
Bone–> facilitate osteoblast/osteoclast activity

45
Q

Metabolic Actions of GH/IGF-1

Protein metabolism

A

stiumulates AA uptake/synth and protein anabolism in tissue

46
Q

Metabolic Actions of GH/IGF-1

Carbohydrate metabolism

A

assists in maintaining blood glucose levels
impairs glucose uptake
stimulates liver glycogenolysis

47
Q

Metabolic Actions of GH/IGF-1

Fat Metabolism

A

increase lipolysis, decrease glucose uptake into fat cells

48
Q

Factors that stimulate Gh release from anterior pituitary gland

A

– GHRH (growth hormone releasing hormone) from
hypothalamus
– Elevated sex hormones associated with puberty
– Dietary protein:
 increase ingestion of AA provide building blocks for growth
– Hypoglycemia:
 Inhibits somatostatin (GH inhibitor from hypothalamus)
– Stage 4 (deep) sleep:
 critical for developing children
– Exercise:
 stress “response” to exercise…appropriate physical stress will produce growth

49
Q

Factors that inhibit GH release

A
somatostatin
glucocorticoids
hyperglycemia
Negative feed bqck cycles
excessive androgen levels
50
Q

Three phases of growth phase

A

Phase 1-prenatal to 1st year

phase 2- juvenile growth (1-puberty)
influenced primarily by GH, thyroid hormones and insulin

Phase 3- Puberty
sex steroid hormones (testerone, estrogen) require normal GH levels for optimal influence, steroid hormones increase GH release

51
Q

Hormones that influence growth

A

GH, thyroid, gonodal steroid hormone, Insulin, Cortisol

52
Q

GH0 influence growth

A

metabolic changes to favor growth

direct/indirect stimulus of cell growth (synergistic with IGF-1)

53
Q

Thyroid Hormone- influence growth

A

maintenance fxn on GH
necessary for CNS development
necessary for normal fxn of IGF-1

54
Q

Gonadal Steroid Hormones- influence growth

A

stimulate growth

necessary for normal GH secretion

55
Q

Insulin- Influence growth

A

stimulate fetal postnatal growth

56
Q

Cortisol (neg. impact on growth)

A

inhibits GH, decrease the effects of growth factors on epiphysis

57
Q

Insufficient GH

A

dwarfism, GH dysfunction before growth plates close. impaired Gh secretions or GH receptors

58
Q

Excessive GH

A

Giantism-increase GH before epiphyseal plates close

Acromegaly- increases in GH after epiphyseal plates close

59
Q

TSH (thyroid stimulating hormone)

A

stimulates the synthesis and release of thyroid hormones

60
Q

Gonadotropins Hormone

Luteinizing hormone

A

LH-
Females-ovulation, formation of corpus luteum and synthesis of estrogen progesterone in ovary

Male- stimulates synthesis and secretion of testerone

61
Q

Gonadotropins Hormones

Follicle stimulating horome

A

Females- growth of ovarian follicles and estrogen secretions

Males- stimulates sperm maturation in testicles

62
Q

ACTH

A

adrenocorticotropic hormone

stimulates synthesis and secretion of adrenal cortical hormones

63
Q

MSH

A

melanocyte stimulating hormone

stimulates melanin synthesis/release from melanocytes in the skin.