Lecture 15: Endocrine System Flashcards

1
Q

what are hormones?

A
  • chemical substances that act like messenger molecules in the body.
  • after being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work
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2
Q

what is a tropic hormone?

A
  • hormones that have other endocrine glands as their target
  • most tropic hormones are produced and secreted by the anterior pituitary gland
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3
Q

what are the major endocrine organs?

A
  • pineal gland
  • hypothalmaus
  • pituitary gland
  • thyroid gland
  • parathyroid glands
  • thymus
  • adrenal glands
  • pancreas
  • ovary + testis
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4
Q

what is the role of hypothalamus

A

hypothalamus secretes hormones that stimulate or suppress the release of hormones in the pituitary gland

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5
Q

what are the 3 types of endocrine gland stimuli?

A
  • humoral stimulus
  • neural stimulis
  • hormonal stimulus
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6
Q

what is humoral stimulus?

A
  • hormone release is caused by altered levels of certain critical ions or nutrients
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7
Q

example of humoral stimulus

A

stimulus = low concentration of Ca2+ in capillary blood
response = parathyroid hormone (PTH) which increases blood Ca2+

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8
Q

what is neural stimulus?

A
  • hormone release caused by neural input
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9
Q

example of neural stimulus

A

stimulus = action potentials in preganglionic sympathetic fibres to adrenal medulla
response = adrenal medulla cells secrete epinephrine and norepinephrine

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10
Q

what is hormonal stimulus?

A
  • hormone release caused by another (tropic) hormone
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11
Q

example of hormonal stimulus

A

stimulus = hormones from hypothalamus
response = anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones

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12
Q

what is the pituitary gland?

A
  • important endocrine organ that secretes hormones
  • known as the MASTER gland
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13
Q

what are the hormones of the anterior pituitary gland?

A
  • follicle-stimulating hormone
  • luteinizing hormone
  • adrenocorticotropic hormone
  • thyroid-stimulating hormone
  • prolactin
  • growth hormone
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14
Q

how does the hypophyseal portal system work?

A

1.) when stimulated, hypothalamic neurons secrete either stimulating or inhibiting hormones into the primary capillary plexus
2.) hypothalamic hormones travel through portal veins to the anterior pituitary gland where they stimulate or inhibit the release of hormones made there
3.) in response to stimulating hormones, anterior pituitary gland secretes hormones into the secondary capillary plexus and empties into general circulation

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15
Q

what is the mnemonic for hormones of pituitary gland?

A

FLATPEG (minus e)

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16
Q

follicle-stimulating hormone (FSH)

A
  • named after ovarian follicles
  • promotes egg and sperm development
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17
Q

how do follicle-stimulating hormones reach target cells?

A

hypothalamus + gonadotrophin releasing hormone –> anterior pituitary gland –> ovaries/testes (target cells)

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18
Q

luteinizing hormone (LH)

A
  • named after corpus luteum
  • stimulates ovulation, release of progesterone and production of testosterone
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19
Q

what is corpus luteum?

A
  • temporary mass of cells that forms in an ovary every menstrual cycle and disappears if fertilization does not occur
  • corpus luteum secretes estrogens and progesterone.
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20
Q

how do luteinizing hormones reach target cells?

A

hypothalamus + gonadotrophin releasing hormone –> anterior pituitary gland –> ovaries/testes (target cells)

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21
Q

adrenocorticotropic hormone (ACTH)

A
  • targets the adrenal cortex
  • produces two main classes of hormones; mineralocorticoids and glucocorticoids
  • mineralocorticoid hormone = aldosterone which secretes in response to a drop in blood pressure or blood volume
  • glucocorticoid hormone = cortisol which is releases in response to stressful situations
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22
Q

how do adrenocorticotropic hormones reach target cells?

A

hypothalamus + corticotropin releasing hormone –> anterior pituitary gland –> adrenal cortex = corticosteroids (target cells)

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23
Q

thyroid stimulating hormone (TSH)

A

-targets the thyroid gland to stimulate thyroid hormones
the effects of hormone include:
- increased basal metabolic rate
- regulation of tissue growth and development

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24
Q

how do thyroid-stimulating hormones reach target cells?

A

hypothalamus + thyrotropin-releasing hormone –> anterior pituitary gland –> thyroid gland (target cell)

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25
prolactin hormone (PRL)
- only non tropic hormone - stimulates the production of milk
26
does prolactin have a role in males?
no, there is no known role for prolactin however, there are health impacts in males who have high levels of prolactin such as erectile dysfunction, impotence and thyroid issues
27
growth hormone (GH)
- decreased levels of hormone causes dwarfism - increased levels of hormone causes giantism in children or acromegaly in adults
28
how do growth hormones reach target cells?
hypothalamus + growth hormone releasing hormone --> anterior pituitary gland --> liver to bone, muscles (target cells)
29
what are the hormones of the posterior pituitary gland?
- oxytocin - antidiuretic hormone (ADH) * only secreted here.... produced in hypothalamus*
30
how does the hypothalamus release hormones from the posterior pituitary?
1.) hypothalamic neurons synthesize oxytocin or antidiuretic hormone (ADH) 2.) oxytocin and ADH are transported down axons of the hypothalamohypophyseal tract to the posterior pituitary 3.) oxytocin and ADH are stored in axon terminals in the posterior pituitary 4.) when associated hypothalamic neurons fire, the nerve impulses arriving at the axon terminals cause oxytocin and ADH to be released into the bloodx
31
oxytocin
- promotes positive feelings of psychological trust and bonding (a.k.a cuddle hormone) - known to signal muscle contraction of uterus during childbirth - eject milk form secretory alveoli in breast during breast feeding
32
where is the thyroid hormone (TH) secreted from?
- thyroid gland
33
antidiuretic hormone (ADH) / Vasopressin
- primary function is to decrease amount of water lost at kidneys by inhibiting urine production - is released by posterior pituitary to signal the kidneys to retain water and dilute electrolytes in the body
34
what hormone is released from the pineal gland?
melatonin
35
what is diabetes insipidus?
- inadequate production of ADH where there is severe fluid loss (10L/day), and can cause severe dehydration
36
what is diabetes mellitus?
- also known as diabetes - occurs when the pancreas does not produce enough of the hormone insulin, or the body cannot use insulin properly
37
what are the tropic hormones?
- thyroid stimulating hormone - adrenocorticotropic hormone - follicle-stimulating hormone - luitenizing hormone
38
what are the non-tropic hormones?
- growth hormone - prolactin - melanocyte-stimulating hormone
39
hypophysis
another term for pituitary gland
40
what are the two divisions of the pituitary gland?
- anterior - posterior
41
adenohypophysis
another term for anterior lobe of the pituitary gland
42
neurohypophysis
another term for the posterior lobe of the pituitary lobe
43
what is the infundibulum?
a funnel-shaped extension of the hypothalamus connecting the pituitary gland to the base of the brain
44
what is the melanocyte-stimulating hormone?
- stimulates melanocytes to produce more melanin, which is responsible for skin colour
45
what is the adrenal gland?
- small, triangular-shaped glands located on top of both kidneys - responds to short term and long term stress - produce hormones that help regulate your metabolism, immune system, blood pressure, response to stress etc.
46
what is the adrenal medulla
- located in the inner part of an adrenal gland - controls hormones that initiate the flight or fight response like epinephrine and norepinephrine
47
how does the adrenal gland respond to short-term stress?
- heart rate increase - blood pressure decrease - bronchioles dilate - decreased figestive system activity and urine output - metabolic rate increases
48
how does the adrenal gland respond to long-term stress?
- kidneys retain sodium and water - blood volume and blood pressure increases - proteins and fat converted to glucose for energy = blood glucose increase - immune system suppressed
49
releasing hormones / releasing factors
- hypothalamus release hormones that prompt cells in aterior lobe to release their hormones
50
inhibiting hormones
- hypothalamus secretes hormones that turn off the secretion of hormones by the anterior lobe when necessary
51
target cells
- the cells where hormones have an effect. - target cells are capable of responding to hormones because they display receptors to which the circulating hormone can bind
52
hyposecretion
when the amount of hormones that are released is too low.
53
hypersecretion
when an too much of one or more hormone is secreted from a gland
54
insulin
- beta cells secrete insulin - protein hormone that signals cells to take glucose from the blood and store it is glycogen in the liver - lowers blood sugar
55
what hormones are released from the pancreas?
- glucagon - insulin
56
glucagon
- alpha cells secrete glucagon - protein hormone signals liver cells to release glucose from glycogen stores - raises blood sugar when it falls too low
57
what hormones are released from the gonads?
- testosterone - estrogen - progesterone
58
epinephrine
- increase cardiac output - raise glucose levels in the blood
59
norepinephrine
- regulation of arousal, attention, cognitive function, and stress reactions
60
progesterone
hormone that supports menstruation and maintaining a pregnancy
61
estrogen
growth, development, and physiology of the female reproductive system
62
testosterone
is responsible for the typical male characteristics and helps maintain sex drive + sperm production
63
what is the adrenal cortex?
- secretes various hormones which are all lipid based steroid hormones called corticosteroids
64
what hormones are secreted by the adrenal gland/cortex
- corticosteroids (aldosterone and cortisol)
65
corticosteroids
- type of hormone secreted by the adrenal cortex - two main classes: mineralocorticoids and glucocorticoids
66
mineralocorticoids
- aldosterone is the main type - responds to a decline in blood volume or blood pressure
67
glucocorticoids
- cortisol is the main type - helps deal with stressful situations (i.e anxiety, trauma, infection)
68
what are leydig cells?
the primary source of testosterone or androgens in males
69
what is agromegaly?
- similar to giantism - condition where the body produces too much growth hormone, causing body tissues and bones to grow more quickly in adults