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HLSC 128 - Human Physiology II > Chapter 6 - The Central Endocrine Glands > Flashcards

Chapter 6 - The Central Endocrine Glands Flashcards

1
Q

Do endocrine glands have ducts?

A

no

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2
Q

Where do endocrine glands secrete their hormones?

A

to the interstitial space then into the blood

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3
Q

Hormone Definition

A

a chemical substance that is secreted in low quantities into the blood and exerts a physiological effect on a specific target tissue

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4
Q

What makes the target specific?

A

the receptor sites

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5
Q

Overall Endocrine System Functions

A

-organic metabolism regulation
-water and electrolyte balance
-stress adaptations
-growth and development
-reproductive control
-RBC production
-circulation, digestion, food absorption regulation

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6
Q

The nervous and endocrine system regulate and communicate with the body; what is the difference between the two?

A

the endocrine system is a much less rapid response but its effects are more long term

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7
Q

How is hormone concentration in the plasma controlled?

A

-changes in the rate of hormone secretion

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8
Q

What is a tropic hormone?

A

-a hormone that regulates the production and secretion of another hormone
-they stimulate and maintain these target tissues

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9
Q

What is negative-feedback control?

A

when the output of a system counteracts a change in input

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10
Q

What is negative-feedback used for?

A

maintaining hormone plasma concentration

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11
Q

Set Point

A

the given level of a hormone that should be maintained

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12
Q

Can a hormone switch off its own secretion?

A

yes, via negative-feedback

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13
Q

Positive-Feedback Loop

A

actions of a hormone cause further release of the hormone ie. oxytocin

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14
Q

Neuroendocrine Reflexes

A

combination of neural and hormonal components to produce a sudden increase in hormone secretion ie. cortisol

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15
Q

What is a Dinural (circadian) Rhythm

A

-an endocrine rhythm characterized by regular hormone levels on a 24 hour cycle
-locked on (or entrained) to external cues set by the CNS

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16
Q

What are the 3 ways a hormone can influence another hormone at a target cell?

A
  1. permissiveness
  2. synergism
  3. antagonism
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17
Q

Permissiveness

A

-one hormone must be present in adequate amounts for full exertion of another hormones effect
-one hormone ‘permits’ another

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18
Q

Permissiveness Example

A

-TH permits epinephrine to exert its full effect by increasing the number of epinephrine receptors

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19
Q

Synergism

A

-actions of several hormones are complimentary
-combined effects greater then sum of individual effects

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20
Q

Synergism Example

A

-FSH and testosterone in maintaining sperm production
-influences receptors for each other hormone

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21
Q

Antagonism

A

-one hormone opposes the actions of another hormone

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22
Q

Antagonism Example

A

-When parathyroid hormone stimulates the release of calcium from bones to oppose calcitonin
-also insulin and glucagon

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23
Q

Hyposecretion

A

-an endocrine dysfunction where too little hormone is secreted

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24
Q

Primary Hypo/Hyper Secretion

A

the gland is not secreting enough/too much due to abnormality with the gland

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25
Secondary Hypo/ Hyper Secretion
gland is functioning normally but secreting too little/much due to a deficiency/sufficiency of its tropic hormone
26
Some factors that cause hyposecretion:
-increased hormone removal from blood -abnormal tissue response to hormone -lack of target receptors -lack of enzyme needed for target response
27
Hypersecretion
-an endocrine gland dysfunction where too much hormone is secreted
28
Some factors that cause hypersecretion:
-reduced plasma proteins to bind with the hormone -decreased removal from the blood -decreased inactivation
29
How are hormones grouped?
based on chemical nature
30
Hydrophilic Hormones
-water-loving -highly water soluble -low lipid solubility
31
What are the structure of hydrophilic hormones?
-peptides (short length) and proteins (long length)
32
Example of Hydrophilic Hormones
-Insulin -Catecholamines
33
How are peptides transported in the blood?
as free hormones
34
What are catecholamines?
-hormone derived from amino acid tyrosine
35
Where are catecholamines secreted?
adrenal medulla
36
What is the primary catecholamine?
epinephrine
37
How are catecholamines transported in the blood?
half bound to plasma proteins
38
Where do peptides and catecholamines bind on their target cell?
surface
39
Lipophilic Hormones
-lipid-loving -high lipid solubility -poor water solubility -thyroid and steroid hormones
40
Thyroid hormone is an _____ _______ derivative
iodinated tyrosine
41
Steroid hormones are a ________ derivative
cholesterol
42
What are amines?
-when catecholamines and thyroid hormones are grouped together being both tyrosine derivatives
43
How are thyroid and steroid hormones transported in the blood?
mostly bound to plasma proteins
44
Where is the receptor site for thyroid and steroid hormones?
inside the target cell
45
How do hydrophilic hormones affect their target cell?
they change/activate the 2nd messenger system to alter target protein activity that produce the effect
46
How do lipophilic hormones affect their target cell?
they activate new genes to make new proteins and produce the effect
47
Where do steroid hormones come from?
adrenal cortex and gonads
48
Where do thyroid hormones come from?
thyroid follicular cells
49
How are peptide hormones processed?
-synthesized by ribosomes in RER -processed in Golgi to become active hormones -packaged in Golgi and sent off in secretory vesicles -released by exocytosis
50
What are the most common peptide hormones?
polypeptides
51
How are steroid hormones processed?
-cholesterol from cell stores is modified sequentially by enzymes -the final product depends on the cell type
52
Can steroid hormones be stored?
no, they are released immediately by diffusion to the blood (cholesterol is the only thing stored)
53
What is another name for the pituitary gland?
hypophysis
54
Where is the pituitary gland located?
the punching bag located below the hypothalamus
55
What connected the pituitary gland to the hypothalamus?
infundibulum
56
What is another name for the posterior pituitary? Why?
-neurohypophysis -it is mainly composed of nervous tissue
57
What is another name for the anterior pituitary? Why?
-adenohypophysis -it is mainly made of glandular epithelial tissue
58
What controls the release of hormones from the anterior and posterior pituitary glands?
the hypothalamus
59
How do the posterior pituitary and hypothalamus connect?
via a neural pathway
60
How do the anterior pituitary and hypothalamus connect?
via a unique vascular link
61
What forms the neuroendocrine system?
the posterior pituitary and hypothalamus
62
Does the posterior pituitary actually produce any hormones?
no, only storage and release of 2 hormones made in the hypothalamus
63
Which 2 hormones are stored and released by the posterior pituitary?
vasopressin (aldosterone) and oxytocin
64
What does vasopressin do?
-conserves water during urine formation -causes vasoconstriction
65
What does oxytocin do?
-stimulate uterine contractions during childbirth -milk ejection during breast feeding
66
What are the 6 hormones produced and released by the anterior pituitary?
-Follicle-stimulating Hormone (FSH) -Adrenocorticotropic hormone (ACTH) -Thyroid-stimulating hormone (TSH) -Luteinizing hormone (LH) -Prolactin (PRL) -Growth hormone (GH)
67
Of the 6 hormones released by the anterior pituitary, which one is NOT tropic?
prolactin (PRL)
68
The anterior pituitary makes and releases what kind of hormones?
peptide
69
What does TSH do?
-stimulates secretion of thyroid hormone (TH) -stimulates growth of the thyroid gland
70
What does ACTH do?
-stimulates secretion of cortisol by the adrenal cortex -promotes growth of the adrenal cortex
71
What does LH do in females?
-responsible for ovulation and luteinization -regulates secretion of ovarian sex hormones (estrogen and progesterone)
72
What does LH do in males?
-stimulates testosterone secretion
73
What does FSH do in females?
-stimulates growth and development of ovarian follicle -promotes ovarian estrogen secretion
74
What does FSH do in males?
-sperm production
75
What does GH do?
-regulates overall body growth -important in intermediary metabolism
76
What does PRL do?
-enhances breast development and milk production (females)
77
What 2 things control pituitary hormone release?
1. hypothalamic hormones 2. feedback by target gland hormones
78
What do hypothalamic hypophysiotropic hormones do?
they stimulate or inhibit secretion of anterior pituitary hormones
79
How many hypothalamic hypophysiotropic hormones are there? What are they called?
7: -Thyrotropin-releasing hormone (TRH) -Corticotropin-releasing hormone (CRH) -Gonadotropin-releasing hormone (GnRH) -Growth hormone releasing hormone (GHRH) -Growth hormone inhibiting hormone (GHIH) -Prolactin-releasing hormone (PRH) -Prolactin-inhibiting hormone (PIH)
80
What does thyrotropin-releasing hormone do?
stimulates release of TSH and prolactin
81
What does corticotropin-releasing hormone do?
stimulates ACTH release
82
What does gonadotropin-releasing hormone do?
stimulates FSH and LH release (from the same cells)
83
What does growth hormone-releasing hormone do?
stimulates release of GH
84
What does growth hormone-inhibiting hormone do?
inhibits release of GH and TSH
85
What does prolactin-releasing hormone do?
stimulate release of prolactin
86
What does prolactin-inhibiting hormone do?
inhibit prolactin release
87
What controls the secretion of hypophysiotropic hormones?
88
Hypothalamic-hypophyseal Portal System
-the vascular network between the anterior pituitary and hypothalamus -blood flows from one capillary bed through connecting vessel to another capillary bed
89
What 3 things are involved in growth?
-protein synthesis -lengthening of bones -increase in size and number of cells in soft tissues
90
Is GH entirely responsible for growth?
no
91
What other factors influence growth?
-genetic determination of maximum growth capacity -diet -chronic diseases -stress -normal growth-influencing hormone levels
92
Is growth continuous?
no, it happens in 2 bursts
93
What promotes fetal growth?
-placental hormones -NOT GH
94
Postnatal Growth Spurt
-during first 2 years of life
95
Pubertal Growth Spurt
-during adolescence
96
Hyperplasia
-stimulated by GH -increasing the number of cells -done by stimulating cell division and preventing apoptosis
97
Hypertrophy
-stimulated by GH -increasing the size of cells -done by favouring protein synthesis
98
Do bones grow from the ends or the centre?
centre
99
What is the difference between cartilage and bone?
cartilage is not calcified
100
What separates the diaphysis (shaft) from the epiphysis (end)?
epiphyseal plate, a layer of cartilage (chrondrocytes)
101
How do bones grow in length?
-chondrocytes at the epiphysis multiply and widen epiphyseal plate -the epiphysis and diaphysis are pushed farther apart and the older cartilage is calcified
102
Does GH promote growth directly or indirectly? How?
indirectly by stimulating the production of somatomedins
103
What are somatomedins?
-peptide mediators from the liver -they are structurally similar to insulin and also called Insulin-like Growth Factors (IGF)
104
What does IGF do?
acts on bone and soft tissue to bring about growth promoting actions
105
What does IGF stimulate?
-protein synthesis -cell division -hyperplasia and hypertrophy
106
When can bone growth occur?
when the epiphyseal plate is cartilaginous or "open"
107
What do "closed" growth plates mean?
-the epiphyseal plate has ossified -no more growth can occur -marks the end of adolescence
108
When is GH tropic?
-when it acts on the liver to produce IGF -promoting cell division, protein synthesis, and bone growth
109
When is GH not tropic?
-its metabolic actions unrelated to growth: fat breakdown, decreasing glucose uptake by muscles, increasing liver glucose output
110
How does GH increase blood fatty acids?
enhancing breakdown of triglycerides stored in adipose tissue
111
How does GH increase blood glucose levels?
-decreasing glucose uptake by muscles -increasing glucose from the liver (stimulating glycogen breakdown)
112
When is GH secretion highest? Lowest?
-highest in adolescence -lowest in adults
113
What are the effects of lowered GH secretion in adults?
-decrease in lead body fat -decrease in bone mass -expansion of adipose tissue -thinning of skin
114
What does dwarfism result from?
hyposecretion of GH
115
What does hypersecretion of GH in childhood lead to?
gigantism
116
What does hypersecretion of GH in adulthood lead to?
acromegaly (tumour of GH producing cells)
117
What is the pineal gland?
a tiny pinecone shaped structure in the centre of the brain
118
What does the pineal gland release?
melatonin
119
What is melatonin?
-the hormone that peaks during darkness -promotes sleep
120
Melatonin Function
-synchronizing circadian rhythms with light-dark cycles -promotes sleep -influences reproductive activity -acts as an antioxidant -enhances immunity
121
What is the Suprachiasmatic nucleus?
-master biological clock

HLSC 128 - Human Physiology II (11 decks)

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