Hormones and The Endocrine System (LO #1-35) Flashcards
1
Q
Compare the signaling systems of the Nervous System vs. the Endocrine System.
A
Nervous System: faster
Endocrine System: longer lasting
2
Q
What do neuronal signals in the Hypothalamus lead to?
A
Hormonal pituitary signals, sense and respond
3
Q
What type of feedback does a neuronal signal that leads to a hormonal signal in the anterior pituitary an example of?
A
(+ or -) negative feedback
4
Q
What type of feedback does a neuronal signal that leads to a hormonal signal in the posterior pituitary an example of?
A
positive feedback
5
Q
In the sympathetic autonomic nervous system, a neuronal signal leads to what?
A
(+)Adrenal Medulla, release of neurohormone (epinephrine)
6
Q
In the parasympathetic autonomic nervous system, a neuronal signal leads to what?
A
autonomic ganglion, (+ or -) endocrine glad cell, hormone release to effector organs, note Varicosities
7
Q
Describe Autocrine signaling
A
Autocrine substance acts on the same cell that secreted the substance
path flow- local cell, ISF, autocrine substance, receptor on same cell
8
Q
Describe Paracrine signaling
A
target calls in close proximity to the site of release of paracrine substance
path flow- local cell, ISF, paracrine substance, receptors on target cell
9
Q
Describe Neurotransmitter signaling
A
neuron or effector cell in close proximity to site of neurotransmitter release
path flow- nerve cell, electrical signal, neurotransmitter, ionotropic receptors, target cell
10
Q
What do Endocrine Glands do?
A
take raw materials from the blood and use them to build hormones that go back into the blood
11
Q
What do Exocrine Glands do?
A
take raw materials from the blood, send them out of the body
12
Q
Describe Neurohormone Signaling
A
target cell in one or more distance places in the body, path flow- hormone secreting gland cell, hormone, blood vessel, target cell
13
Q
Describe solubilityPeptide/Protein Hormones.
A
hydrophilic (Lipophobic, water soluble) i.e. not membrane penetrating
14
Q
Discuss the sequential synthesis and secretion of typical peptide hormones.
A
Synthesis: rough ER, preprohormone shortened to prohormone
Packaging: Golgi, Prohormone folds into hormone
Storage: Secretory Vesicles, mature hormone
Secretion: of hormone and any pro-fragments
15
Q
What is a preprohormone made of?
A
long string of amino acids
16
Q
What is a prohormone made out of?
A
short string of amino acids
17
Q
Describe synthesis of peptides/protein hormones.
A
in ER and Golgi
18
Q
Describe storage of peptides/protein hormones.
A
packaged into vesicles found in cytosol
19
Q
Describe major form in plasma of peptides/protein hormones.
A
free/ unbound
20
Q
Describe receptor location of peptides/protein hormones.
A
plasma membrane
21
Q
Describe excretion rate of peptides/protein hormones.
A
fast (minutes)
22
Q
Describe signaling of peptides/protein hormones.
A
second messengers, enzyme activation by receptor, intrinsic enzymatic activity of receptor
23
Q
Describe solubility of Catecholamine Hormones.
A
hydrophilic, water soluble, non-membrane penetrating
24
Q
Describe synthesis of Catecholamine Hormones.
A
synthesized from Tyrosine (an amino acid)
25
Describe major form in plasma of Catecholamine Hormones.
free/unbound
26
Describe receptor location of Catecholamine Hormones.
plasma membrane
27
Describe excretion rate of Catecholamine Hormones.
fast (minutes)
28
Describe signaling of Catecholamine Hormones.
second messengers, enzyme activation by receptor, intrinsic enzymatic activity of receptor
29
Describe solubility of Steroid Hormones.
Hydrophobic, lipid soluble
30
Describe synthesis of Steroid Hormones.
synthesized from cholesterol, synthesis in adrenal cortex and gonads
31
What are the properties of Catecholamine Hormones similar to?
Peptide/protein hormones
32
Describe major form in plasma of Steroid Hormones.
protein bound
33
Describe receptor location of Steroid Hormones.
Intracellular
34
Describe excretion rate of Steroids Hormones
slow (hours to days)
35
Describe signaling of Steroids Hormones
intracellular receptors directly alter gene transcription
36
Discuss the synthesis and secretion of steroid hormones in the adrenal cortex.
-happens in adrenal gland, produces cortisol, aldosterone, and DHEA
-cholesterol is source material
37
Discuss the synthesis and secretion of steroid hormones in the gonads.
-happens in gonads, produces testosterone, progesterone, and estrogen
38
What enzyme is used in the production of testosterone?
5-alpha reductase
39
What enzyme is used in the production of estrogen?
Aromatase
40
Describe the major form in plasma of Thyroid Hormone.
protein bound
41
Describe the location of receptors for Thyroid Hormone.
intracellular
42
Describe the most common signaling for Thyroid Hormone.
intracellular receptors directly alter gene transcription
43
Describe the rate of excretion for Thyroid Hormone.
slow (hours or days)
44
What is Thyroid Hormone? What are the two types?
an amine, T4 and T3
45
Describe the synthesis for Thyroid Hormone.
derived from tyrosine, not cholesterol
46
Describe the solubility for Thyroid Hormone.
very hydrophobic, lipid soluble
47
Discuss the possible fates of a hormone after secretion.
After an endocrine cell produces a hormone and the hormone enters the bloodstream, the hormone can
1. Be excreted in urine and feces
2. Be inactivated by metabolism
3. Be activated by metabolism
4. Bind to a receptor on target cells, and produce a cellular response (3 can lead to 4)
48
Describe the location of a hydrophobic hormone receptor.
intracellular
49
What happens in general when a hydrophobic hormone binds to a receptor?
1. Messenger diffuses out of capillaries from plasma to interstitial fluid
2. messenger diffuses across lipid bilayers of the plasma membrane and nuclear envelope to enter the nucleus and bind to its receptor
3. The activated receptor complex then functions in the nucleus as a transcription factor, defined as a regulatory protein that directly influences gene transcription
4. Hormone receptor complex binds to DNA at a regulatory region of a gene, an event that typically increases the rate of the gene's transcription into mRNA
5. The mRNA molecules move out of the nucleus to direct the synthesis, on ribosomes, of the protein gene encodes
6. Protein synthesis
7. Cell response
50
Describe the receptor locations of hydrophilic hormones.
extracellular surface of the target cell
51
Describe what happens in general when a hydrophilic hormone binds to a receptor.
the receptors trigger one or more signal transduction pathways for plasma membrane receptors, which directly influences G proteins coupled in the plasma membrane to effector proteins (ion channels and enzymes) that generate second messengers
eg. cAMP, Ca2+, IP3
PKA and PLC-PKC cascades
52
List and describe five important characteristics of hormone receptors
1. They determine which tissues respond to an endocrine "broadcast"
2. High sensitivity
3. Huge signal amplification (because of signal transduction mechanisms)
4. Hormone levels influence expression of their own receptors; up-regulation and down-reglation
5. Hormones can have a permissive effect on expression of other hormone's receptors
53
What is the difference between up-regulation and down-regulation?
up-regulation occurs when there is a continued low concentration of hormones, and it increases the number of receptors
down-regulation occurs when there is a continued high concentration of hormones, and it decreases the number of receptors
54
Use Thyroid Hormone as an example to describe what is means for a hormone to be permissive of another hormone.
Thyroid hormone is permissive of epinephrine effects because thyroid hormone increases the number of epinephrine receptors on target cells
Thyroid hormone goes to nucleus, bind to receptor, induces protein synthesis, some of which are epinephrine receptors
55
What is the difference between hyper-secretion and hypo-secretion?
hyper-secretion: too much hormone pathology wherein negative feedback is ignored
hypo-secretion: too little hormone, often glandular destruction or loss of key regulators
eg for both: tumors and auto-immunity
56
What is the difference between hyper-responsiveness and hypo-responsiveness?
hyper-responsiveness: receptor up-regulation or altered functions within the second messenger cascades
hypo-responsiveness: receptor down regulation or altered functions within the second messenger cascade
57
Where do a large portion of endocrine signals begin?
Hypothalamus
58
What does the hypothalamus regulate?
Activity of cells in the anterior pituitary gland and neurohormone release from the posterior lobe of the pituitary gland
59
Which lobe of the pituitary gland receives tropic hormones from the hypothalamus via portal vessels?
anterior lobe
60
What is the physiological response of the anterior lobe after receiving tropic hormones?
increase or decrease in secretions
61
Do you know the parts of the hypothalamus and pituitary gland? (LO 14)
yes
62
What is the posterior lobe of the pituitary gland composed of?
axon terminals of neurons that begin in the hypothalamus
63
What is the relationship between the Hypothalamus and the Posterior Pituitary gland?
Action potentials propagate from hypothalamus to posterior lobe terminals and trigger exocytosis of neurohormones
64
List the peptides released from the Posterior Pituitary
1. Anti-Diuretic Hormone (ADH, aka vasopressin)
2. Oxytocin
65
What is the role of ADH released from the Posterior Pituitary?
water retention via kidney, constriction of smooth muscle in blood vessels
66
What is the role of Oxytocin released from the Posterior Pituitary?
contraction of uterine smooth muscle during birth, milk secretion from breast tissue upon suckling, bonding behaviors in both females and males (also parental)
67
Describe the hormone exchange that occurs in the blood of the anterior pituitary
Hypophysiotropic hormone enters goes from the blood stream into anterior pituitary gland cells, then anterior pituitary hormone enters the bloodstream and go out to entire body via venous circulation
68
Describe Tropic Action.
to affect secretion, can be positive or negative
69
Describe Trophic Action.
to promote the growth and development of targets
70
Describe a generic three gland cascade
Stimulus
Hypothalamus
Hormone 1 (hypophysiotropic)
Anterior Pituitary
Hormone 2 (trophic)
Gland 3
Hormone 3
Target Cell
71
Describe Long Loop negative feedback
affects anterior pit and hypothalamus
72
Describe Short Loop negative feedback
affects hypothalamus
73
List the Hypothalamus Hypophysiotropic Hormones
GnRH, GHRH, SST, TRH, DA, CRH
74
List the Anterior Pituitary Hypophysiotropic Hormones
FSH, LH, Growth Hormone, TSH, Prolactin, ACTH
75
What does Corticotropin-releasing hormone (CRH) do?
stimulates secretion of ACTH
76
What does Thyrotropin-releasing hormone (TRH) do?
stimulate secretion of TSH
77
What does Growth Hormone Releasing Hormone (GHRH) do?
stimulates secretion of GH
78
What does Somatostatin(SST) do ?
inhibits secretion of GH
79
What does Gonadotropin-releasing hormone (GnRH) do?
stimulates secretion of LH and FSH
80
What does Dopamine(DA) do?
Inhibits secretion of prolactin
81
Other than dopamine, what chemical class are all hypophysiotropic hormones? What about dopamine?
peptides, catecholamine
82
What cell type does FSH and LH affect?
gonadotrophs (gonads)
-germ cell development
-secrete hormones
83
What cell type does growth hormone affect?
somatotrophs
-largest group
- liver, tissues and organs
-protein synthesis, carbohydrate and lipid matabolism
84
What cell type does TSH affect?
thyrotrophs (thyroid)
-secretes T3 and T4
85
What cell type does Prolactin affect?
lactotrophs (breasts)
-breast development and milk production in women
86
What cell type does ACTH affect?
corticotrophs (adrenal cortex)
-secretes cortisol
87
Describe the histology of the Thyroid Gland (LO 19)
composed primarily of colloid-filled spheres enclosed by a single layer of follicular cells
88
Describe Thyroid Hormone in the thyroid gland.
1. Thyroid Hormone is conjugated to thyroglobulin, a protein that cannot pass across membranes and is stored in colloid
2. Thyroid hormone is stored until stimulated to be secreted
3. Thyroid hormone is transported in the blood bound to carrier proteins
4. Thyroid hormone is lipophilic amine hormone, and thus binds to receptors located inside the target cell
89
Describe the structure of thyroid hormone, distinguishing between T3 and T4
follicles trap iodide for the synthesis of thyroid hormones
T4 (thyroxine)
-90% of secretion
-storage pool in blood
-converted to T3 in target cells
T3(triiodothyronine)
-most active, potent form
90
Describe the steps of thyroid hormone synthesis, storage, and regulated secretion in 7 steps. (LO 21)
1. Iodide is co-transported w/ Na+
2. Diffusion
3. Iodide is transported to colloid, oxidized, and attached to rings of tyrosines on thyroglobulin
4. The iodinated ring of the MIT or DIT is added to a DIT at another spot
5. Endocytosis of Thyroglobulin containing T3 and T4 molecules
6. Lysosomal enzymes release T3 and T4 from TG
7. T3 and T4 secretion
91
What starts the cascade of thyroid hormone synthesis?
TSH binding to receptor
92
Where do steps 2, 5, 6, and 7 of thyroid hormone synthesis occur?
follicle cell
93
Where do steps 3 and 4 of thyroid hormone synthesis occur?
lumen of the follicle (colloid)
94
Describe the 3-gland cascade that depicts the regulated secretion of thyroid hormone
neural inputs
hypothalamus, TRH secretion
plasma TRH increases
anterior pituitary, TSH secretion
plasma TSH increases
thyroid gland, T3 and T4 secretion
plasma thyroid hormone increases
TRH, TSH, T3 and T4
95
List and describe the actions of Thyroid Hormone
1. Affects virtually every cell, increase gene transcription and protein synthesis (especially metabolism-related gene products)
2. Controls basal metabolic rate (BMR) and thus body temperature (rate at which cells burn fuel to maintain basic life functions), mainly increased by Na+/K+ ATPase
3. Permissive of beta-adrenergic receptor (catecholamine) expression (symp NE and Epi)
4. Essential fro fetal CNS development and function, equally important for proper adult nervous system function
5. Permissive for overall growth and development
96
Describe Hypothyroidism.
causes: damage to thyroid gland, lack of iodide in diet, auto-immune thyroiditis (Hashimotos)
Goiter occurs if cause is iodine deficiency
symptoms: low BMR, cold intolerance, fatigue, inappropriate weight gain, weak pulse, decreased alertness and cognitive function
no T3 and T4 secretion, no negative feedback occurs
trophic effects
97
Describe Hyperthyroidism.
causes: auto-immune stimulation of TSH receptors (Grave's disease), anti-bodies mimic TSH hormone, stimulate the receptor
symptoms: high BMR, heat intolerance, nervous/irritability, insomnia, inappropriate weight loss, constant fight or flight state, exopthalmos
increase in T3 and T4 secretion, too much negative feedback
trophic effects
98
Name the two parts of the adrenal glands.
Medulla (inner) and Cortex (outer)
99
What defines the layers of the adrenal glands?
preferential presence of enzymes
100
Name the three layers of the cortex and what they are made of
zona glomerulosa - aldosterone
zona fasciculata - cortisol and small amount of androgens
zona reticularis - androgens (DHEA) and small amount of cortisol
101
What is the medulla made up of?
epinephrine and norepinephrine
102
What type of hormones does the adrenal medulla secrete?
amine hormones (phillic catechols)
103
What is the adrenal medulla considered?
a modified sympathetic ganglion that does not give rise to postganglionic fibers
104
Name the three adrenergic receptors and their location
Alpha one- smooth muscle (contraction, constrict)
Beta one- cardiac muscle
Beta two - smooth muscle (relaxation, dilation)
105
Describe the 3-gland cascade for the regulated secretion of cortisol.
neural inputs
hypothalamus, CRH secretion
plasma CRH increases
anterior pituitary, ACTH secretion (corticotroph cells)
plasma ACTH increases
adrenal cortex, cortisol secretion (zona fasciculata)
plasma cortisol increases
target cells
106
What increases during distress?
cortisol
107
What increases during eustress?
epinephrine
108
Name the functions of the Adrenal Catecholamines in stress
Epi reinforces, supports sympathetic nervous system effects initiated by NorEpi during fight or flight stress response:
-dilates respiratory airways and increases ventilation
-reduces digestive activity
-inhibits bladder emptying
-dilates blood vessels to heart skeletal muscles
-mobilizes glucose (from liver), triglyceride (from adipose)
-dilates pupils and increases cardiac function
-increases CNS alertness
109
Where does the regulation of cortisol secretion occur?
Zona Fasciculata
110
Describe the functions of cortisol during Basal Levels
1. Metabolic effects: liver glucose production (for neurons) between meals (provides substrates and maintain enzymes involved in metabolic homeostasis)
2. Permissive of adrenergic receptors in the cardiovascular system (maintain adequate mean arterial blood pressure)
3. Anti-inflammatory/ anti-immune (prevent hyper-response), cortisone
4. Fetal/neonatal development of brain, intestines, lungs, glands (production of surfactant in last months of gestation)
111
Describe the functions of cortisol during Stress Levels
1. Metabolic effects (glucose sparing), mobilize glucose, fatty acids, amino acids for fuel and tissue repair
2. Bone resorption (reabsorbs parts of long bone), Ca2+ mobilization, repair bone breaks
3. Support sympathetic responses (fight, flight) keep MAP up
4. Stimulates erythropoietin (replace RBCs) bleeding wound
5. Anti-inflammatory/ Immunosuppression (helps to prevent rejection of transplanted organs)
6. Psychological/Analgesic, cortisol elevates mood, endorphins co-released w/ ACTH; inhibit pain
7. Inhibition of non-essential functions: reproduction/growth
112
What are symptoms of chronic stress and what causes them?
weak bones, high BP due to too much cortisol
113
Describe Primary Adrenal Insufficiency
aka Addison's disease, hypo-secretion of cortisol
no cortisol, no negative feedback
issue in adrenal cortex where cortisol is secreted
causes: destructive tumors, infection, auto-immune destruction
symptoms: hypotension, hypoglycemia, high plasma ACTH
114
Describe Secondary Adrenal In sufficiency
hypo-secretion of cortisol
loss or low ACTH in plasma (anterior pituitary and tropic hormone)
symptoms are same as primary
115
Describe the difference between Cushing's Syndrome and Cushing's Disease
Hyper-secreting tumor, tumors ignore negative feedback
Syndrome is primary, takes place in adrenal cortex
Disease is secondary, takes place in anterior pituitary
symptoms: osteoporosis, hyperglycemia, high bp, immunosepression, obesity of trunk and face and yet wasting of arms and legs
116
How do long bones actually elongate?
at growth plates next to their epiphysis where rapid mitosis and differentiation occur under the influence of both local and circulating hormones.
117
What two hormones are involved in the elongation of bones?
IGF-1 and GH
118
When do growth plates fuse?
After prolonged exposure to sex steroids (estrogen and testosterone), disappear after puberty
119
What two things are found within the marrow cavity?
EPO from kidney, RBCs
120
Describe what occurs in the epiphyseal plate
hyperplasia - chondrocytes undergoing cell division
hypertrophy - older chondrocytes enlarging
121
Describe what occurs in the shaft
osteoblasts covert cartilage into bones
122
How does Growth Hormone influence growth?
stimulates protein synthesis
123
How does Insulin influence growth?
"builder"
124
How does Thyroid Hormone influence growth?
permissive for growth hormone secretion, permissive for development of central nervous system
125
How does estradiol influence growth?
stimulates secretion of growth hormone at puberty, causes eventually epiphyseal closure
126
How does cortisol influence growth?
inhibits growth, stimulates protein catabolism
127
What are the major effects of growth hormone?
promotes growth, stimulates protein synthesis, anti-insulin effects
128
Describe the 3 gland cascade for the regulated secretion of growth hormone and IGF-1
stimulus: excersize, stress, fasting, low plasma glucose, sleep
Hypothalamus: GHRH secretion and SST secretion(inhib)
Anterior Pit: GH secretion
Liver and other cells: IGF-1 secretion
IGF-1 : neg feedback on GHRH and GH, pos feedback on SS
GH: pos feedback on IGF-1 and SS, neg feedback on GHRH
SS: neg feedback on GH
GHRH: pos feedback on GH
Target cells : hypertrophy and hyperplasia
129
Describe short stature
GH goes down, so IGF-1 goes down
insensitive GH receptors
lack of IGF-1 secretion (GH okay)
Insensitive IGF-1 receptors
130
Compare acromegaly and gigantism
both caused by tumors of the anterior pituitary that hyper-secrete GH
acromegaly- too much GH after the epiphyseal plates close (thick bones)
gigantism- too much GH before epiphyseal plates close
131
Where is capillary bed #1?
median eminence
