final review first half of course Flashcards
1
Q
2 types of hormones released by hypothalamus
A
- releasing hormones
- inhibiting hormones
2
Q
hypothalamus: 6 releasing hormones
A
- thyrotropin-releasing hormone (TRH)
- growth hormone-releasing hormone (GHRH/somatocrinin)
- gonadotropin-releasing hormone (GnRH)
- melanotropin-releasing hormone (MRH)
- corticotropin-releasing hormone (CRH)
- kisspeptin
ALL OF THESE ARE EXCITATORY (releasing hormones)
3
Q
hypothalamus: 3 inhibiting hormones
A
- somatostatin (growth hormone-inhibiting hormone/GHIH)
- gonadotropin inhibitory hormone (GIH)
- dopamine
ALL OF THESE ARE INHIBITORY
4
Q
CRH
A
corticotropin-releasing hormone
stimulates secretion of ADRENOCORTICOTROPHIC hormone
5
Q
‘tropic’ means…
A
nourishing
ie. adrenocorticotrophic means a hormone that nourishes the adrenal gland
6
Q
GRH
A
gonadotropin-releasing hormone
controls release of…
a. luteneising hormone (LH)
b. follicle stimulating hormone (FSH)
7
Q
TRH
A
thyrotropin-releasing hormone
tells pituitary to release more TSH (thyroid stimulating hormone)
8
Q
MRH
A
melanotropin-releasing hormone
stimulates secretion of melanotropin
9
Q
kisspeptin
A
initiates secretion of GnRH at start of PUBERTY
involved in sexual maturation, but unclear exactly how
10
Q
dopamine
A
dopamine is usually excitatory
but in endocrine system it’s inhibitory
prolactin-inhibitory hormone
11
Q
somatostatin
A
inhibits secretion of:
a. growth hormone (GH)
b. thyroid-stimulating hormone (TSH)
also inhibits production of insulin, glucagon, secretin
12
Q
3 main anterior pituitary hormones
A
recall: ant pit is involved in controlling hormone secretions from adrenal glands, thyroid and gonads
- corticotropin-related peptides (painkillers, stress response)
a. ACTH, MSH, beta-endorphins - somatomammotropins (breast milk, growth)
a. growth hormone (GH/somatotropin), prolactin - glycoproteins (thyroids, gonads, sex hormones)
a. TSH, LH, FSH
13
Q
way to remember the 3 anterior pituitary hormones
A
- painkillers/stress response
(ACTH, MSH, beta-endorphins) - growth
(somatostatin/GH, prolactin) - sex
(TSH, LH, FSH)
14
Q
corticotropin-related hormones (class of hormones released by anterior pituitary)
A
- ACTH
^stimulates things to be released from adrenal glands: glucocorticoids, mineralocorticoids, steroids
- beta-endorphins
^endogenous opioids resembling opiates through action as “natural pain killer”
15
Q
why are anterior pituitary hormones often considered poplypeptide-tropic hormones?
A
because they stimulate various physiological processes
either by acting directly on tissue or by causing other endocrine glands to release hormones
16
Q
somatomammotropin hormones (class of hormones released by anterior pituitary)
A
- GH
^promotes linear growth and enhances amino acid uptake and mRNA transcription/translation (increased protein synthesis)
- prolactin
^promotes breast development, initiates milk synthesis
17
Q
glycoproteins (class of hormones released by anterior pituitary)
A
- TSH
^works on thyroid to stimulate uptake of iodide and release of thyroid hormones
- LH and FSH
^bind to receptors in ovaries and testes, regulate gonadal function, stimulate sex steroid production and gamete development
18
Q
posterior pituitary hormones
A
oxytocin and vasopressin
19
Q
posterior pituitary hormone release
A
- neurosecretory cell bodies produce vasopressin and oxytocin and transport them to the posterior pituitary
- vasopressin and oxytocin are transported and stored in vesicles at axon terminals
- released in response to neural signals via exocytosis and enter the bloodstream this way
so posterior hormones can be released as quick as neural impulses
20
Q
anterior pituitary hormone release
A
slower than posterior
- axon terminals of hypothalamic neurons release neurohormones near capillaries that give rise to portal vessels
- neurohormones from portal vessels stimulate or inhibit the release of hormones from anterior pituitary cells
- anterior pituitary hormones leave gland via the blood
21
Q
oxytocin/vasopressin release is as fast as…
A
neural impulses
released from vesicles via exocytosis
super quickly in response to neural impulses
22
Q
vasopressin
A
anti-diuretic hormone (makes us retain water/not pee)
causes blood vessel constriction to help deal with blood loss
23
Q
5 points on oxytocin
A
- influences mammal REPRODUCTIVE function
- important during BIRTH
- causes UTERINE CONTRACTIONS
- used to INDUCE LABOUR
- involved in SUCKLING REFLEX
24
Q
what does the pineal gland secrete?
A
melatonin
produced by pinealocytes
25
thyroid gland
large bilateral structure in the neck
consists of many spherical follicles
26
what does thyroid gland produce
T3 and T4
iodinated substances - their production relies on dietary levels of iodate
27
low levels of dietary iodate
reduced thyroid function
hypertrophy
28
hypertrophy manifests how?
swelling in the neck
29
what do thyroid hormones do?
increase OXIDATION RATES in tissues
3 general effects in mammals:
a. metabolism
b. growth and differentiation
c. reproduction
30
2 thyroid hormones
T3: triiodothyronine
T4: thyroxine
both are fat soluble and diffuse rapidly across membrane but need carrier protein to get through blood
31
4 key functions of T3 and T4
1. regulation of METABOLISM
2. control BRAIN and NS DEVELOPMENT
3. sexual MATURATION
4. TEMPERATURE regulation
32
hyper and hypothyroidism
hyperthyroidism: too much T3 and T4
^weight loss, fast HR, weak menstrual cycle, shaky hands
hypothyroidism: not enough T3 and T4
^weight gain, constipation, cold sensitivity
33
Ronaldo has...
hypothyroidism
34
parathyroid glands
located at rear of thyroid
release PTH (parathyroid hormone)
35
PTH
parathyroid hormone
released by parathyroid, produced by C cells of the thyroid
elevates CALCIUM LEVELS in the BLOOD
36
what makes PTH
C cells of the thyroid gland
37
how does PTH increase blood calcium levels?
1. increases reabsorption of calcium from bone and gut
2. inhibits phosphate reabsorption from kidney (reduces calcium clearance)
38
C cells
cells in the thyroid
make PTH and calcitonin
^modulate blood calcium levels
39
CT
calcitonin
released from thyroid's C cells
works in opposition to PTH
lowers blood calcium levels by INHIBITING CALCIUM RELEASE from bone
40
CT and PTH are both directly controlled by...
blood calcium levels
no releasing hormones are involved in their concentrations
41
endocrine cells of the pancreas
most of the pancreas is exocrine: exocrine cells produce/release digestive juices
but islets of Langerhans are endocrine, and are nested among the exocrine cells
42
islets of Langerhans
islands of endocrine tissue nested within the exocrine cells of pancreas
4 types of cells within these islands
43
4 types of cells within islets of Langerhans
1. alpha
2. beta
3. theta
4. polypeptide-secreting cells
44
alpha cells
in islets of Langerhans of pancreas
release glucagon
45
what does glucagon do once it's released from pancreas?
travels to liver
starts glycogenolysis
46
glycogenolysis
caused by glucagon action in liver
breakdown of stored glycogen (into glucose)
acts in opposition to insulin to increase blood glucose levels
47
glucagon, glycogen and glucose
glucagon is released from alpha cells
glucagon causes glycogen to convert to glucose
results in higher blood levels of glucose
48
ultimately, alpha cells...
increase blood levels of glucose
49
what do beta cells produce?
insulin
50
what does insulin do?
lowers blood sugar
controls efficient movement of energy from blood into the cells
51
glucagon and insulin
work in opposition
glucagon increases blood sugar
insulin lowers blood sugar
52
2 causes of diabetes
type 1: insulin deficiency
(pancreatic islets are destroyed by autoimmune response)
type 2: decreased insulin response
(potensh from eating too much sugar or from your insulin not working right)
53
what do theta cells release?
somatostatin
somatostatin inhibits glucagon and insulin release locally in the pancreas
54
adrenal glands 2 parts
1. adrenal cortex
2. adrenal medulla
55
adrenal cortex
distinct cellular zones with distinct functional roles
1. zona glomerulosa
2. zona fasciculata
3. zona reticularis
56
zona glomerulosa
whorls of epithelial cells
aldosterone
57
zona fasciculata
orderly bands of cells
glucocorticoid
58
zona reticularis
disorganized cells
sex hormones
59
adrenal medulla
made of chromaffin cells
chromaffin cells come from embryonic development, they're derived from primitive neural tissue
releases monoamine hormones in response to neural signals
60
chromaffin cells
derived from primitive neural tissue
make up the adrenal medulla
part of ANS
respond to signals from the spinal cord
61
monoamine hormones released by adrenal medulla
1. epinephrine
2. norepinephrine
3. dopamine
also release enkephalins (proteins)
62
why is adrenal medulla important in fight or flight?
because it releases epinephrine and norepinephrine
and because chromaffin tissue receives neural signals super fast (part of ANS since derived from primitive neural tissue)
receives info through direct spinal cord innervations
63
how does adrenal cortex receive info?
through the blood - so it's slower
(reminder: it releases aldosterone, glucocorticoids and sex hormones)
64
2 functions of gonads
1. hormone production
2. gamete production
65
3 functions of steroid hormones
1. gamete development
2. behaviours that bring sperm and egg together
3. development of secondary sex characteristics
66
seminiferous tubules
part of testes
where spermatogenesis occurs
contains sertoli and leydig cells
67
sertoli cells
located along base of seminiferous tubules
facilitate progression from germ cells to spermatozoa
68
leydig cells
interstitial cells between seminiferous tubules
produce androgens/testosterone in response to LH from anterior pituitary
69
leydig cells produce androgens/testosterone in response to...
LH from the anterior pituitary
70
what does it mean to say the ovaries are "compartmentalized"?
its different areas have different functions
follicles, stroma, corpora lutea
71
germinal epithelia in fetal ovary
fetal ovary has germinal epithelia that will eventually develop into primordial follicles
infant ovaries have 500 000 immature follicles
72
how many immature follicles in infant ovaries?
500 000
73
how many eggs do women ovulate between puberty and menopause?
400
74
atresia
continual degeneration of follicles throughout life
no additional gametes are formed postnatally
75
stroma
neoendocrine connective tissue of endocrine glands
76
follicles
epithelial cell-lined sacs that contain an egg
77
egg/ovum
haploid female gamete
contained in follicles
78
corpora lutea
endocrine structures that form from remnants of ovarian follicles after egg has been released
secrete progestins
79
progestins
secreted by corpora luteum
prepare uterine lining for blastocyst implantation
80
each primary follicle consists of...
an ovocyte (immature egg)
81
granulosa cells
epithelial cells that surround each ovocyte
produce activin and inhibin (peptide hormones)
82
theca cells
surround granulosa cells during follicular maturation
participate in estrogen synthesis
83
antrum
space between ovum and surrounding epithelial cells
filled with fluid prior to ovulation
84
ovum is called what as the antrum enlarges?
tertiary follicle
85
antrum fluid
rich in steroid hormones
aka follicular fluid
86
follicle at its maximum size
Graafian follicle
87
granulosa and theca cells after ovum release
undergo rapid mitosis
capillaries generated by theca cells vascularize the granulosa cells
88
corpora lutea formation
forms from the rapid mitosis of the theca and granulosa cells after ovum release
(and vascularization of granulosa cells)
89
zona pellucida
multiple layers of epithelial cells that surround the follicle
90
what does placenta form from?
tissues from blastocyst and maternal uterus
91
what does placenta do for fetus?
1. maintains nutritional, excretory and respiratory functions
2. supplies steroid and peptide hormones for mother and fetus
92
placenta tie to pregnancy tests
pregnancy tests measure HCG (human chorionic gonadotropin)
HCG is a hormone produced by rudimentary placenta right after blastocyst implantation
93
HCG
hormone produced by rudimentary placenta
right after blastocyst implantation
94
relaxin
produced by corpora lutea during pregnancy
softens pelvic ligaments
to allow enough stretch for passage of fetus head through pelvis
95
what do supplementary tropic hormones of the placenta do?
stimulate...
gonadal, mammary, adrenal and thyroid functions
96
supplementary tropic hormones released by placenta
1. chorionic gonadotropin
2. chorionic somatommamotropin (placental lactogen)
3. chorionic corticotropin
4. chorionic thyrotropin
97
chorionic gonadotropin (hCG)
1. maintains corpora luteum function (progestin secretion) during pregnancy
2. inhibits ovulation during pregnancy
98
what hormone helps inhibit ovulation during pregnancy?
hCG - chorionic gonadotropin
99
how are the endocrine cells of the gastrointestinal tract organized?
primitive organization
scattered around the gut
100
gastrointestinal tract: what kind of endocrine communication?
intracrine/autocrine
gastrointestinal hormones regulate the cells in which they're produced
(considered more primitive process than endocrine mediation)
101
main gastrointestinal hormones
1. secretin
2. cholecystokinin
3. ghrelin
act to supplement ANS during digestion
102
blastocyst
cluster of dividing cells made by fertilized egg
early stage of embryo
103
secretin
released by duodenal mucosa
in response to food passing into small intestine
stimulates pancreas to produce secretions to aid in digestion
104
cholecystokinin (CKK)
released by lining of small intestine
may be involved in satiation of food intake
causes exocrine pancreas to secrete digestive enzymes
causes gallbladder to contract/release bile
105
where outside of gut has CKK been found?
brain
neuromodulator and neurotransmitter
106
gastrin
peptide hormone
secreted by mucous layer of stomach (produced in antral glands of stomach)
induces water and electrolyte secretion from stomach, liver, pancreas
107
ghrelin stimulates release of what?
GHRH from anterior pituitary
108
where is ghrelin made?
endocrine cells in stomach
109
what happened when ghrelin was injected into mice?
food intake increased
fat deposition increased
110
what happens if you give humans ghrelin?
food intake increases by about 30%
111
when do ghrelin concentrations peak?
before a meal
decrease after a meal
112
2 pattern types for internal hormonal regulation
1. regulation by physiological by-products generated in response to hormonal action (thermostat)
^ie. parathyroid hormone is released when blood calcium levels drop and stops when the levels have normalized
2. regulation by stimulatory/inhibitory effects of other hormones
^ie. GnRH is regulated by negative feedback chain
113
negative feedback
key part of hormonal regulation
regulatory system that stabilizes a process by reducing its output once a certain level has been reached
114
positive feedback
part of hormonal regulation
regulatory system that accelerates a process by increasing output
generally less frequent, must be tightly controlled
ie. short term stress response (can continue for too long)
115
methods by which hormones can affect the levels of their own receptors
1. up regulation - similar to positive feedback
^hormone causes increase in its amount of receptors
2. down regulation - similar to negative feedback
^hormone causes decrease in its amount of receptors
116
how do hormonal messengers invoke intracellular responses?
via signal transduction
chemical hormonal message is transformed into intracellular events that ultimately affect cell function
begins with hormone binding to receptor, ends with final response in target cell
117
signal transduction in steroid hormone cells
steroid hormone receptors are located in the cell (nucleus or cytosol)
steroids are lipid-soluble so pass cell membrane to bind with the intracellular receptors
hormone binds their receptor and travel to nucleus
here, they regulate gene transcription
118
signal transduction in peptide/protein hormones
peptide/protein receptors are located in cell membrane
2 types of activity
a. intrinsic enzymatic activity: enzymes in cytoplasm activate intracellular proteins
b. second messenger: g-coupled proteins activate when hormone binds receptor which activates proteins
119
example of species that produces asexually
white spotted bamboo shark
disadvantage: less genetic diversity
120
sex differences and evolutionary flexibility
sex differences result in more evolutionary flexibility
because of increased genetic diversity
through separation of haploid gametes and recombination in offspring
having a combination of genetic material means more flexibility
121
what mating system produces more sexual dimorphism?
polygamous (more than monogamous)
ie. prairie voles are monogamous and it's almost impossible to tell them apart
ie. elk are polygamous and they have clear differences
122
nature or nurture? sexually dimorphic behaviours
product of both
reflect role of biology and environment (socialization)
ie. boys more likely to hang out in large groups, rough and tumble pay
ie. girls are more likely to hang out in twos and threes, more verbal communication
123
5 levels of mammalian sexual differentiation
1. chromosomal sex
2. gonadal sex
3. hormonal sex
4. morphological sex
5. behavioural sex
each level affects the next one
124
how is chromosomal sex determined
by whether the male contributes an x or y
(because female always contributes an x)
xx: female
xy: male
125
germinal ridge
bipotential primordial gonad, which is essentially a thickening of the germinal ridge
each undifferentiated fetus has this
turns into either ovaries or testes
126
what is needed for germinal ridge to develop into testes?
SRY gene from the Y chromosome
it produces TDF (testis determination factor)
127
SF-1
steroidogenic factor 1
in combination with TDF, produces a transcription factor
this transcription factor regulates expression of S09X gene
128
protein products of SRY and SOX9 leads to...
germinal ridge turning into the testis
if they're absent, the germinal ridge turns into the ovaries
129
testis development requires
SRY gene > TDF
SF-1 > transcription factor > SO9X
130
what gene might be required for normal ovarian development?
Wnt4
this is important because used to be thought that mere absence of SOX9 and SRY would leave to development of ovaries
but this suggests there might be another gene that must be present for ovaries to develop
131
what do hormonal secretions from the developing gonads determine?
whether fetus develops in male or female-typical manner
mammalian testes produce androgens
mammalian ovaries don't produce any hormones in high levels
132
in presence of ovaries or complete absence of any gonads, what will happen to development?
will follow a female-typical pathway
133
interesting finding: sexually dimorphic transcription of over 50 genes in brains of mice at 10.5 days post conception
50 chromosomal genes were different between males and females
even at 10.5 days post-conception, wayyyyy before gonads were developed
suggests that sex genes are mediated by chromosomes, not gonads
134
interesting finding: cell culture from XY mice contain more cells expressing tyrosine hydroxlyase than XY mice, irrespective of the gonadal sex of the embryos from which the cells were taken
again, suggests that chromosomes are mediating sex to a certain degree
independently from gonads
135
morphological sex
Mullerian (female) and Wolffian (male) systems are both present early on in embryonic development
dual anlagen
136
dual anlagen
rudimentary basis of accessory sex organs
apparatus for both male and female accessory organs
137
mullerian duct system develops into...
fallopian tubes
uterus
upper vagina
(and Wolffian ducts regress)
138
wolffian duct system develops into...
seminiferous tubules
vas deferens
(and Wolffian ducts regress)
139
male accessory organs require...
1. Mullerian inhibitory hormone (MIH)
2. testosterone
^both are products of the embryonic testes
140
roles of testosterone and MIH
testosterone: stimulates Wolffian duct development (masculinization)
MIH: causes regression of Mullerian system (defeminization)
141
what's responsible for differentiation of external genitalia?
androgens
142
what happens to external genitalia in response to androgens?
1. urethral groove fuses
2. penis develops from genital tubercle
3. scrotum develops from fusion of genital folds
143
what happens to external genitalia in absence of androgens?
1. clitoris develops from genital tubercle
2. labia develop from genital folds
144
what do accessory sex organs look like at 6 weeks?
still undifferentiated
1. urethral groove
2. urogenital sinus
3. anal fold
145
male vs female external genitalia
male: penis, scrotum
female: labia, clitoris
146
what controls mating behaviour in both sexes?
gonadal steroid hormones
147
castrated male mice
castration stops mounting behaviour
but replacement therapy restores mounting behaviour to regular levels
148
does injecting adult female rats with testosterone cause them to display mounting behaviour?
no
suggests that at some point in development, female rats lose the potential to exhibit male typical behaviour
149
do male rats injected with estrogen display female behaviour?
no
150
151
Charles Phoenix study phase 1 - effect on genitalia
LARGER dose mother's female offspring: external genitalia indistinguishable from males
SMALLER dose mother's female offspring: no visible changes to external genitalia ("unmodified females")
152
Charles Phoenix study phase 2 - groups
3 groups of males and females
a. smaller dose prenatal testosterone
b. larger dose prenatal testosterone
c. control
153
Charles Phoenix study phase 2 steup
all 3 groups were:
1. gonadectomized
2. injected with estrogen and progesterone (to stimulate female sexual behaviour)
3. paired with male guinea pig
4. later, all injected with androgens (to stimulate male behaviour)
5. paired with female guinea pig
154
Charles Phoenix study findings
androgens given to guinea pigs prenatally...
a. decreased tendency of both small and large dose females to display lordosis
b. increased tendency of both small and large dose females to display mounting in response to testosterone therapy
c. caused no deleterious effects on mounting behaviour or other masculine traits in males who were treated
155
Charles Phoenix study takeaway
there's a clear distinction between prenatal hormonal action which causes organization of neural substrates for behaviour
and the actions of hormones in adulthood that cause the activation of these behaviours
led to the organization-activation hypothesis of sexually dimorphic behaviours
156
organizational/activational hypothesis of sexually dimorphic behaviour
1. sex hormones work during prenatal stage to permanently organize the nervous system in a sex-specific manner
2. during adulthood, these same hormones have activation effects
157
cyclic vs tonic gonadal function
cyclic: in females
^cycles in mating behaviour
tonic: in males
^continuous willingness to mate
158
LH profile in males and females
males:
a. steady pulsatile release
females:
a. pulsatile release
b. negative feedback is broken
c. big increase in FSH and LH secretion
d. after ovulation, pulsatile release resumes
159
what controls LH levels?
gonadotropins secreted from anterior pituitary
GnRH > LH > gonadal function
160
LH affects what in males and females
males: testis and testosterone
females: ovaries and estrogen/progesterone
161
females: GnRH negative feedback is altered how?
on a cyclical basis
162
females: breaking GnRH negative feedback loop
females escape negative GnRH feedback loop on a cyclical basis
1. estrogen levels increase
2. surge of GnRH in response
3. GnRH stimulates anterior pituitary to release FSH and LH (ovulation
4. after ovulation, negative feedback system re-engages
163
GnRH and negative feedback
happens in both males and females
high GnRH levels feedback to gonads, anterior pituitary and hypothalamus
this slows GnRH, gonadotropin and gonadal steroid secretion
164
chromosomal to gonadal sex
Y chromosome contains SRY gene
SRY gene causes expression of TDF
TDF (when combined with SOX9 which needs SF1) leads to development of the testis
without TDF and SOX9, the ovaries develop
165
partial SRY expression
leads to incomplete gonadal differentiation
166
chromosomal XY but no SRY
male mice develop ovaries
167
chromosomal XX but insert SRY
female mice develop testes
168
Swyer syndrome
no sex glands develop (no testes or ovaries)
in individuals with XY chromosomes that lack SRY gene
don't experience puberty without intervention
external female genitalia, but no menstruation
functionless gonads
169
Swyer syndrome is classified as...
a disorder of sexual development (DSD)
DSDs encompass any condition where chromosomal, gonadal or anatomic sex is abnormal
170
Swyer syndrome treatment
hormonal replacement therapy
171
hormonal to morphological sex
if individual is XY, testosterone and MIH must be secreted at the correct time
if MIH isn't secreted at the correct time, Mullerian system will develop
depending on hormonal secretion, it's possible for both systems or for neither to develop
172
intersex
variety of conditions in which reproductive/sexual anatomy doesn't fit definition of male or female
ie. discrepancies between external genitalia and internal sexual organs
ie. when both systems develop (either separately or intertwined)
173
is intersex a medical problem?
no, but it may signal underlying metabolic concern
used to be considered a problem and people would be surgically altered
174
spectrum of hormonal to morphological sex
two intersecting continua
1. masculinization to de-masculinization
2. feminization to de-feminization
potential for multiple diff outcomes
175
Prader scale
scoring system for grading degrees of genital masculinization
0: un-virilized female
5: completely virilized female
176
completely virilized female
5 on Prader scale
female who appears male at birth
but empty scrotum because no testicals
177
what's responsible for external genitalia differentiation?
androgens
androgenic metabolites
178
androgenic metabolite that's crucial for genital fusion process
5 alpha-dihydrotestosterone (5 DHT)
testosterone is converted to 5 DHT by an enzyme
179
high 5 DHT in females
leads to development of male external genitalia
180
5 DHT deficiency
genetic males (XY)
a. ambiguous genitalia
b. small, undescended testes
c. considered female at birth and raised female
d. testosterone masculinizes body at puberty
181
puberty and people with DHT deficiency
testosterone masculinizes body
a. male-typical musculature
b. auxiliary hair growth
c. genitalia develop to resemble penis and scrotum
182
Turner syndrome
congenital condition
lack second chromosome (X0) or damage to second chromosome
female external appearance
limited ovarian development
don't reach puberty without treatment
183
congenital adrenal hyperplasia
caused by lack of 21-hydroxylase enzyme
leads to overproduction of adrenal androgens
(progesterone also needs 21-hydroxylase to create other important hormones)
184
congenital adrenal hyperplasia: congenital males versus females
males: causes no problems
females: causes moderate/severe masculinization of genitalia
185
androgen insensitivity syndrome
absence of functional androgen receptors
XY individuals with this syndrome have normal appearing female external genitalia
but vagina is often short, no menstruation occurs, and they're sterile
sexed and reared as girls
186
when do people discover they have androgen insensitivity syndrome?
puberty
when menstruation fails to occur
187
3 trisomic anomalies
1. XXY - Klinefelter syndrome
2. XYY
3. XXX
188
Klinefelter syndrome
XXY
extra X chromosome
presence of Y chromosome is sufficient for SRY to act and for masculinization to occur
usually sterile because of decreased sperm production
often severe learning disabilities
189
what are people with Klinefelter syndrome sexed as at birth?
males
190
Klinefelter syndrome mainly reflects
variation in the androgen receptors
191
modern organizational-activational hypothesis of sexual differentiation
1. expands variables that affect sex differences
a. genes
b. hormones
c. environment
2. expands time period in which organizational effects occur
a. to pre-pubertal period
essentially, modern version sees things as much less fixed
192
sex differences in behaviour often show significant overlap between the sexes...
but there are often greater differences in behaviour between members of the same sex
than between individuals of the opposite sex
essentially, there's considerable overlap between the sexes
