Regulation of Reproduction Flashcards
1
Q
what is the role of the nervous system in repro regulation?
A
trnslate external stimulus into neural signals that act of reproductive tissues
2
Q
how does the endocrine system function in repro regulation?
A
relies on hormones
3
Q
what does the work of the neural system in repro regulation?
A
neurotransmitters
4
Q
what are neurotransmitters?
A
smaller molecules produced by a neuron and released into a synapse; acts on a target cell
5
Q
how far do neurotransmitters travel?
A
very short distances; less than 1mm
6
Q
what type of responses are achieved by neurotransmitters?
A
fast; milliseconds
7
Q
how long do signals propogated by neurotransmitters last?
A
short duration
8
Q
what is the release of neurotransmitters stimulated by?
A
other nerves
9
Q
what are hormones in terms of the response?
A
they are catalysts that SIGNAL a response; they do not make the response
10
Q
what are hormones, very generally?
A
larger molecules produced by endocrine glands
11
Q
what does the endocrine system do?
A
acts on cells or tissues at another location in the body
12
Q
what does the endocrine system (and its hormones) need to function?
A
the circulatory system
13
Q
how far do hormones travel?
A
a very long way, all around the body
14
Q
how long does it take for hormones to cause a response/last?
A
minutes to a day
15
Q
what is the slower transport of the endocrine syste, stimulated by?
A
other nerves and tissues
16
Q
list the 2 reproductive pathways of the neural system
A
- simple neural pathway
2. neuroendocrine reflex
17
Q
describe the simple neural pathway
A
secretion of neurotransmitter at target tissue
18
Q
what system does the simple neural pathway involve?
A
the neural system only
19
Q
describe the neuroendocrine refelx
A
secretion of neurohormone into blood to remote target tissue
20
Q
what systems are involved in the neuroendocrine reflex and what is their role?
A
neural stimulus, endocrine response
21
Q
give the fancy definition of neurotransmitter
A
substance released at synapses for neuronal propogation of the electrical impulse, produced by neurons
22
Q
define a neurohormone?
A
substance released by neurons directly into the blood
23
Q
list the 5 stimuli that initiate the simple neural reflex
A
- thermal
- tactile
- visual
- auditory
- olfactory
24
Q
decribe the signalling of the simple neural reflex
A
signal sent via afferent neuron to spinal cord, which sends a signal back via the Efferent neuron, causing neurotransmitter release into target tissue, resulting in a response
25
describe the signalling of the neuroendocrine reflex
spinal cord sends info to hypothalamus, which causes an endocrine response
26
compare and contract the signalling of the simple neural and neuroendocrine reflexes
simple neural reflex involves only nerves, afferent and efferent, and takes place only in the spinal cord, response is achieved via neurotransmitter. neuroendocrine signalling also takes place in the spinal cord, but that signal leaves the spinal cord and goes to the hypothalamus, causing an endocrine response (view flow chart from notes for more info)
27
what is the HPG axis?
hypothalmic-pituitary-gonadal axis
28
give some examples of an neuroendocrine response in males and females
female: milk ejection
male: emission
29
what is the HPG responsible for in females?
the estrous cycle
30
what is the HPG responsible for in males?
testosterone and sperm production
31
what is the HPG responsible for in males and females?
sexual behavior
32
list the 3 centers of the hypothalamus that are important in repro regulation
1. surge center (FEMALES ONLY)
2. tonic center
3. paraventricular nucleus (PVN)
33
what is the surge center also known as?
pre-ovulatory GnRH center
34
what is the role of the surge center? (2)
1. specific hypothalamic nuclei in females that responds to high estradiol
2. secretes high GnRH during short time period
35
what is the role of the tonic center?
controls tonic release of GnRH; daily background levels of GnRH
36
what is and what is the role of the paraventricular nucleus?
it is a discrete band of nerve cells that innverate the posterior pituitary; stimulates release of oxytocin and ADH
37
what is GnRH?
gonadotropin releasing hormone
38
what is LH?
luteinizing hormone
39
describe the roles of the PVN and the posterior pituitary gland in the production and release of oxytocin and ADH
the PVN PRODUCES the hormones, the posterior pituitary RELEASES them
40
relate the surge center and the tonic center to a faucet in terms of GnRH secretion
surge center is like a faucet turned all the way up for a short period of time, resulting in a lot of GnRH produced quickly; the tonic center is like a steady dripping faucet; constantly secreting low levels of GnRH
41
what does HPPP stand for?
the hypothalamo-pituitary portal plexus
42
what is the hypothalamo-pituitary portal plexus?
a vascular network that gives a direct line of communication between the hypothalamus and the anterior pituitary glandd
43
give 2 advantages of the HPPP
1. only need small amounts of hormone to causes an effect
| 2. hormone does not have to circulate through entire body; decreasing hormone breakdown
44
describe the connection between the hypothalamus and the posterior pituitary gland (3)
1. no portal system
2. neurons from PVN that terminate in posterior pituitary
3. direct neurological connection = faster
45
define a positive feedback loop
hormone that stimulates a biological process that further increases levels of that hormone
46
give an example of a positive feedback loop
oxytocin release during parturition
47
define a negative feedback loop
levels of a hormone that bring about a biological response that inhibits further release of that hormone
48
which type of feedback loop contributes tto homeostasis?
negative
49
give an example of a negative feedback loop in reproduction
testosterone production
50
describe a positive feedback loop in terms of its effect on a gland or tissue
positive feedback loop exerts a stimulatory effect on another gland or tissue
51
describe a negative feedback loop in terms of its effect on a gland or tissue
negative feedback loop exerts an inhibitory effect on another gland or tissue
52
give two examples of reproductive negative feedback loops
1. gonadal steroids: testosterone, progesterone, estradiol
| 2. protein hormones: inhibin
53
give two examples of reproductive positive feedback loops
1. gonadal steroids: estradiol (yes, is both +/-)
| 2. oxytocin during parturition/nursing: milk letdown
54
how does the endocrine system cause a response?
relies on hormones
55
list and describe the 2 factors that influence the biological activity of a hormone
1. presence of receptors for a hormone on a target cell: is the reason for side effects of hormonal therapy, hormone goes to all cells with receptors, but only certain cells with receptors produce desired response
2. half-life of the hormone in circulation: want some hormones to have a short half-life
56
what is a target cell?
tissue or cell that possesses receptors for a hormone
57
define half-life
the time required for 1/2 of a hormone to disappear from the blood/body
58
give a hormone that we would want to have a short half-life and why
oxytocin, don't want super contractions all the time
59
list the 4 characteristics of reproductive hormones
1. exert biological response at the nanogram or picogram level in blood
2. short half-lives
3. exert cell response by binding to specific receptors in or on cell
4. stimulate phenotypic response in cell through biochemical, metabolic, or genomic response
60
list the 3 ways to classify a hormone
1. source
2. biochemical classification
3. mode of action
61
describe source as a way to classify a hormone
where does it come from
62
list and describe the 4 biochemical classifications of a hormone
1. peptide: small chain of amino acids
2. protein/glycoprotein: larger than peptides
3. steroid/lipids: fat soluble, diffuse through membranes
4. fatty acids
63
which biochemical classes of hormones can't be given orally and why?
peptides and proteins/glycoproteins; would just be digested in stomach acid, must be injected instead
64
what does the glyco in glycoprotein mean?
there is a carbohydrate attached to the protein
65
what shape is the structure of a steroid? how are they usually administered?
a ring, can be given orally or in a CIDR
66
what shape is the structure of a lipid? how are they usually administered?
chain, usually injected
67
what does the pineal gland produce? what animals does it play an important reproductive role in?
melatonin; seasonal breeders
68
describe mode of action as a way to classify a hormone
what/how many target tissues? what does it communicate in that target tissue?
69
list two peptide hormones and what type of peptides they are, and what their class of hormone is
1. oxytocin: nanopeptide (9 amino acid chain)
2. GnRH: decapeptide (10 amino acid chain)
these are neurohormones
70
list three glycoproteins hormones and their class of hormones of the first two
1. FSH
2. LH
3. TSH
FSH and LH are gonadotropins
71
what is an alpha subunit?
common among many hormones, the same in many hormones
72
what is a beta subunit?
unique to each hormone; allows specificity
73
what are all sex steroids derived from?
cholesterol
74
how do you get different sex steroids from cholesterol?
chop off carbons
75
how many carbons does cholesterol have?
27
76
list 3 sex hormones derived from cholesterol and their carbon count
1. progesterone: 21 carbons
2. androgens: 19 carbons
3. estrogen: 18 carbons
77
what are the 2 androgens derived from cholesterol?
testosterone and dihydrotestosterone (DHT)
78
what enzyme converts testosterone to dihydrotestosterone?
5a (alpha) reductase
79
what form of estrogen is the predominant form for cyclicity?
estradiol, E2
80
what form of estrogen is responsible for postmenopause?
estrone, E1
81
what form of estrogen is responsible for pregnancy?
estriol, E3
82
what does the 1, 2, or 3 of estrogen indicate?
the number of hydroxyl groups
83
what enzyme converts androgens to estrogens?
aromatase
84
list the 6 steroid functions
1. cellular effects
2. feedback
3. behavior
4. secondary sex characteristics
5. bone ossification
6. pregnancy
85
describe steroids in terms of how they get to and into target cell
fat soluble, diffuse through membranes
86
what is the rate limiting step in cholesterol conversion and where does it take place?
conversion of cholesterol to pragnenolone, happens in mitochondria
87
where does the conversion of pragnenolone to progesterone take place?
in the smooth endoplasmic reticulum
88
when testosterone is combined with 5a reductase, what is the product?
dihydrotestosterone
89
when testosterone is combined with aromatase, what is the product?
estradiol
90
describe the structure of protaglandins
fatty acids
91
list the 4 functions of prostaglandins
1. luteolysis: CL breakdown
2. ovulation: locally
3. inflammation
4. blood pressure
92
what is important about Cox-2 inhibitors?
they can inhibit ovulation by stopping conversion of cyclooxygenase to PGH2, which will eventually convert to PGF2a and PGE2
93
list the 3 domains of a transmembrane hormone receptor
1. extracellular domain
2. transmembrane domain
3. intracellular domain
94
where does a hormone bind in a hormone receptor?
in the extracellular domain
95
what is phosphorylation?
the addition of a phosphate (PO4) group to a protein or a small molecule
96
what do phosphatases do?
remove a phosphate group from a protein
97
what does dephosphorylate mean?
to remove a phosphate group from a protein
98
what can the phosphorylation or activation of a protein do?
can lead to genomic and metabolic changes in cells and synthesis of new products
99
what can a protein be compared to in terms of activation?
like a firefighter, ready to go, just needs the addition of PO4 group
100
list the 2 types of second messenger signalling pathways
1. cAMP second messenger
| 2. Ca2+ second messenger
101
list 5 hormones that use the cAMP second messenger signalling pathway
1. LH
2. FSH
3. prolactin
4. eCG
5. hCG
102
describe the reasoning behind steroid hormone receptors
steroids are fat soluble so the passively diffuse through the cell membrane into the cytoplasm of the cell, however, they are not water soluble so they are transported in blood bound to water soluble proteins
103
is the steroid hormone binding process quicker or slower than the second messenger signalling pathway? why?
slower, have to change DNA
104
list the 4 steps in the steroid binding process
1. steroid transported in circulation bound to a carrier protein
2. steroid diffuses through membrane
3. steroid binds to a receptor (in nucleus or cytoplasm), and the HORMONE-RECEPTOR COMPLEX binds to DNA, causing step 4
4. gene transcription for new products
105
list the 4 steroid hormones that use the steroid binding process
1. testosterone
2. DHT
3. E2 (also uses 2nd messenger systems)
4. P4
106
list the 3 types of hormone potency/action based on pattern and duration of hormone release
1. basal
2. episodic
3. sustained
107
describe basal hormonal release, give an example
hormone generally stays low but with fluctuations, responsible for background levels
ex. GnRH release from tonic center
108
describe episodic hormonal release, give an example
in response to positive feedback or stimulation
| ex. GnRH release from surge center
109
describe sustained hormonal release
| give an example
remains elevated for a relatively long period of time (days to weeks)
ex. progesterone from CL during diestrus
110
list the 2 repro peptide hormones
1. oxytocin
| 2. GnRH
111
list the 3 sources of oxytocin
1. produced by neurons in the hypothalamus (PVN)
2. released by posterior pituitary
3. corpul luteum
112
list the 3 female targets of oxytocin and their functions
1. uterus: myometrium contractions for parturition
2. mammary glands: milk letdown
3. endometrium: to signal for PGF2a
113
list the male target of oxytocin and its function
epididymal tail, ductus deferens: pre-ejaculatory movemement of sperm (emission)
114
what is the source of GnRH? (give 2 specific sites in this source)
hypothalamus only
- tonic and surge center in females
- tonic center only in males
115
list the male and female target of GnRH and its function
anterior pituitary: causes release of FSH or LH
116
list one repro protein hormone and its source
prolactin, from the anterior pituitary
117
list the 2ish female targets of prolactin and the 4 overall functions
1. mammary gland: growth during pregnancy (1), milk production after parturition (2)
2. in some species: ovulation and corpus luteum formation (also 3rd function)
4th function: maternal bonding
118
list the male target of prolactin and its 3 functions
1. testis: for testosterone production, spermatogenesis, and paternal bonding
119
describe the difference between oxytocin and prolactin
oxytocin signals for milk letdown during nursing, prolactin signals to the mammary gland to produce milk
120
give the one repro polypeptide hormone and its source(s)
relaxin, from the placenta and/or corpus luteum
121
list the female target of relaxin and its function
targets the cervix/pelvic ligaments to widen the birth canal for parturition
122
does relaxin only target cervical/pelvic ligaments? what is the importance of this?
no; it targets all ligaments and is the reason why pregnant mothers experience loose joints and whatnot
123
give the male function of relaxin and its source in males
enhances sperm motility, we are unsure of its source
124
list the 6 glycoprotein repro hormones
1. Follicle stimulating hormone (FSH)
2. Luteinizing hormone (LH)
3. Equine Chroionic Gonadotropin (eCG)
4. Human Chorionic Gonadotropin (hCG)
5. Inhibin
6. Activin
125
from where and when is FSH released?
from the anterior pituitary gland in response to GnRH
126
give the female target and functions (2) of FSH
granulosa cells: induce follicular development and estradiol synthesis
127
give the male target and functions (3) of FSH
sertoli cells: support sertoli cells, support spermatogenesis, and regulate blood-testis barrier through tight junctions between sertoli cells
128
from where and when is LH released?
from anterior pituitary in response to GnRH SURGE (can also have tonic secretion in male and female, but tonic only in males bc that's all they have)
129
give the three female targets and functions of LH
1. theca cells: testosterone secretion
2. granulose cells: induces ovulation
3. luteal cells: support of forming corpus luteum
130
what induces the ovulation accomplished by granulose cells?
surge levels from theca cells
131
give the male target and function of LH
leydig cells: testosterone production
132
what did Equine chorionic gonadotropin (eCG) used to be called?
PMSG: pregnant mare serum gonadotropin
133
describe the subunits of eCG?
same alpha subunit as LH, FSH, with a unique beta subunit that can also bind to LH receptors
134
where is eCG found naturally? what is its use?
only found naturally in horses; but can be administered to other species for FSH activity
135
where in equines is eCG found?
endometrial cups, a structure unique to horses composed of the placenta and endometrium
136
at one point during gestation are endometrial cups found in equines?
d 35- d110-140 of gestation
137
is there a male target of eCG?
no, female only
138
give the target of eCG and its 4 functions
the ovary: induces accessory CL formation, which increases P4, has LH like activity in mares, has FSH like activity in other species
139
what is the source of hCG?
the embryo and placenta
140
what hormone is measured by pregnancy tests?
hCG
141
is there a male target of hCG?
no
142
what is the female target of hCG and its 3 functions
corpus luteum: prevents luteolysis, can be used to induce ovulation in mares, has LH like activity in mares
143
give the female source of inhibin
granulose cells
144
give the male source of inhibin
sertoli cells
145
give the male and female target of inhibin and its function
anterior pituitary gland, inhibits FSH secretion
146
what type of feedback does inhibin play a role in?
negative feedback systems
147
give the 3 sources of activin
1. anterior pituitary
2. gonads
3. placenta
148
give the female target and 2 functions of activin
follicle: increases FSH binding and estradiol production
149
give the male target and 2 functions of activin
testis to enhance spermatogenesis and testosterone production
150
list the 3 sex steroid hormones
1. estrogen
2. progesterone
3. testosterone
151
give the female sources (2) of E2
1. granulosa cells
| 2. placenta
152
give the male source of E2
sertoli cells
153
give the 4 reproductive female targets of E2 and their respective functions
1. brain: sexual behavior
2. hypothalamus: GnRH regulation
3. entire repro tract: increase secretions
4. myometrium: contractions for sperm movement
154
does E2 have only reproductive targets?
no, goes to whole body
155
give the male target of E2 and its function
brain: sexual behavior
156
give the 2 sources of progesterone
1. corpus luteum (always produces P4)
| 2. placenta (sometimes produces P4)
157
give the 4 targets of progesterone and their respective functions
1. uterus: uterine secretions
2. mammary gland: increases mammary tissue
3. hypothalamus: inhibit GnRH secretion
4. brain: inhibit reproductive behavior
158
does progesterone have a male source?
no
159
give the female source of testosterone
theca interna cells
160
give the male source of testosterone
leydig cells
161
give the female target of testosterone and its function
granulosa cells: substrate for estradiol
162
give the 3 male targets of testosterone and their respective functions
1. accessory sex glands: secretions
2. seminiferous tubules: promote spermatogenesis
3. epididymis: several functions
163
list the fatty acid repro hormone
Prostalgandin F2a (PGF2a)
164
give the female source of PGF2a
uterine endometrium mostly, can have other sources
165
give the male source of PGF2a
vesicular gland, or prostate if no vesicular gland
166
give the female targets of PGF2a (3) and their respective functions
1. corpus luteum: luteolysis
2. myometrium: uterine tone/contraction
3. follicles: ovulation, localized
167
give the male target of PGF2a and its function
epidiymis: induce daily contractions, part of sperm maturation process
168
list the 7 steps in the female feedback loop
1. tonic GnRH release from hypothalamus to anterior pituitary: tonic release of FSH and LH stimulates next step
2. stimulated follicular development to produce E2 and inhibin (at lower levels)
3. low E2 and inhibin negative feedback to hypothalamus and anterior pituitary to reduce FSH
4. follicle keeps growing and producing higher E2 levels until E2 levels are high enough to stimulate hypothlamus for GnRH surge
5. LH and FSH surge, in response to GnRH surge, causes next step
6. ovulation of largest follicle
7. follicle is luteinized and produces high P4, which has strong negative feedback on hypothalamus, which dampens system
169
list the 5 steps of the cAMP second messenger signalling pathway
1. primary messenger binds to cell receptor and activates a G protein
2. the activated G protein then activates adenylate cyclase, which converts ATP to cAMP (a process that requires energy)
3. cAMP activates protein kinase A (PKA)
4. PKA phosphorylates a protein
5. cell response (communicate with DNA)
170
list the 7 steps of the Ca2+ second messenger pathway
1. primary messenger binds to cell receptor and activates a G protein
2. the activated G protein bnds to the alpha subunit and activates PLC, which associates with PIP2
3. PLC cleaves PIP2 into IP3 and DAG; DAG directly activates protein kinase C, which phosporylates a protein and causes a response inside the cell
4. IP3 is released into the cytoplasm and binds to a channel on the ER (which has high Ca2+ concentrations inside)
5. the ER channel opens, Ca2+ (our secondary messenger) leaves and enters the cytoplasm
6. in cytoplasm, Ca2+ activates existing secretory granules (GnRH response)
7. Ca2+ activates PKC, which phosphorylates a protein and causes a response inside the cell
171
over what period of time does the female feedback loop occur?
17-21 days, depending on the cycle length of the animal
172
over what period of time does the male feedback loop occur?
ongoing loop, repeats every few hours
173
list the 4 steps in the male feedback loop, including 3A and 4A, and 3B and 4B
1. tonic GnRH release from hypothalamus
2. release of FSH and LH from anterior pituitary
3A. FSH targets sertoli cells to (1) promote spermatogenesis, (2) produce inhibin, and (3) produce ABP
4A. inhibin has a negative feedback effect on the anterior pituitary
3B. LH targets Leydig cells to produce testosterone, which can diffuse into sertoli cells and bind to ABP, or is converted to estradiol, which also has a negative feedback effect on the anterior pituitary and hypothalamus
4B. testosterone can go into circulation and cause a negative feedback effect on the anterior pituitary and hypothalamus
174
what is ABP?
androgen-binding protein
