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neuroclin 1 > hormones and sex > Flashcards

hormones and sex Flashcards

1
Q

what are hormones

A

signalling molecule transported by the vascular system

regulate development, physiology, and behaviour

produced by organs (endocrine system) and receptors in all tissues

under control of the brain (hypothalamus) but complex feedback architecture undermines concept of a control hierarchy

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2
Q

endocrine glands

A
  • hypothalamus (controls pituitary gland and others)
  • pituitary
  • thyroid
  • parathyroids
  • adrenal
  • pancreas
  • ovary
  • testis
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3
Q

hormone vs neurotransmitter (6)

A

neurotransmitter
fast onset
short distance
nerve pathways
short duration
digital - neural signalling
targeted actions

hormone
slow onset
long distance - all over body, complements CNS/PNS action
anywhere in circulatory system
long duration
analogue - continuously variable
diffuse actions - begin at a level and then inc/dec accordingly

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4
Q

hormone action loop

A
  1. disturbance occurs (input)
  2. measuring by hormones
  3. comparison to desired state
  4. error noticed
  5. controller commands effector (using hormones)
  6. effector (hormone) returns to desired state
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5
Q

pathway hormones use

A

vascular system - in blood
from secreting cell to target cell - specific receptors

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6
Q

hypothalamus function

A

master controller - knows current state of body and can make adjustments to physiology and behaviour via several routes (inc hormones)

controls pituitary gland - anterior and posterior - for hormone release and sensing

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7
Q

hypothalamus - feedback loops

A

context + sensory inputs = detected by hypothalamus → visceral & somatic motor, neuroendocrine, and bevhavioural responses

context = cortex, amygdala, hippocampal formation
sensory input = visceral and somatic sensory pathways, chemosensory and humoral signals
hypothalamus = compares input to set points and makes changes in response

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8
Q

anterior vs posterior pituitary gland

A

anterior = TSH, ACTH, FSH + LH, endorphin etc.
posterior = oxytocin, ADH

anterior = 2 step release = neurosecretory cell –> blood vessels –> stimulate endocrine cells for hormone release

posterior = single step = neurosecretory cell secretes hormones –> blood vessels

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9
Q

hormone function (2) and common features

A

regulate physiology → motivational states - arousal, aggression, hunger, fear, fatigue etc.

regulate processes → digestion, metabolism, respiration, reproduction, sleep, menstrual cycle etc.

common features = feedforward and feedback signalling, bidirectional influences between body and brain

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10
Q

define chromosomal sex

A

fixed

most humans have 22 pairs of autosomes (like one another) and one pair of allosomes (not comparable_

allosome pair = XX or XY

historically considered to define phenotypic sex

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11
Q

define phenotypic sex

A

modifiable (e.g. hormone treatment)

internal and external genitalia and secondary sex characteristics

XX = ovaries, oviducts, uterus, cervix, vagina etc.

XY = testicles, epididymis, vas deferens, seminal vesicles etc.

often used interchangeably with gender and can influence perceptions

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12
Q

define gender

A

constructed

individuals subjective perception of their sex

emerging from self-appraisal in context or social or cultural norms

genetic and biological contributions are complex

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13
Q

turner syndrome

A

[XO] = missing X chromosome - affects females

shorter height, impaired ovary function

ovaries produce oestrogen and progesterone - reduced levels lead to under development of secondary sex characteristics

therefore diagnosed at puberty

infertility or reduced fertility

treatment = oestrogen and progesterone

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14
Q

Klinefelter’s syndrome

A

[XXY] = extra X chromosome - affects males

[XXXY] variation also possible

taller height, impaired testicular function, language problems, impaired executive function, delayed motor development, reduced body/face hair, feminine fat distribution

testicles produce testosterone - reduced levels = underdevelopment of secondary sex characteristics

therefore evident and diagnosed at puberty

treatment = testosterone

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15
Q

XYY syndrome

A

extra Y chromosome - affects males

taller than XY males, risk of learning or speech development problems - often mild symptoms and IQ in normal range

most are never diagnosed
normal fertility

treatment = supported learning

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16
Q

function of sex chromosomes

A

XX = important for full female sex characteristics development
if missing = underdeveloped

XY = needed for full male sex characteristics development
not possible to have only a Y chromosome

[X] = 1500 genes, [Y] = 80 genes
[X] = info for general development and survival, not just sex characteristics

[Y] = mainly just genes for male gonadal development and sperm function
“functional wasteland” - most DNA seems to be not coding for any specific genes - other than SRY gene

17
Q

SRY gene

A

sex-determining region on Y chromosome
sex-linked - only found on Y - on short arm

important for diversion toward male biological development in utero - at around 6-8 weeks old foetus

SRY present = forms testes
SRY not present = forms ovaries

chemically blocking SRY in XY = genetic male with ovaries
injecting SRY protein in XX = genetic female with testes

18
Q

why do men have nipples

A

formed before SRY gene activates → evolutionary baggage

no strong pressure to drop them from main body plan (Y chromosome instruction doesn’t stop this) as they don’t do any harm

19
Q

chromosomal testing in sports

A

1992 Olympics tested for SRY gene to determine male/female of athletes
* with SRY = not allowed to compete as females
* found later that 8 female athletes had SY gene - had insensitivity to androgen (testosterone is a form of this)
* but they were phenotypically female - so had no advantage

screening replaced in 2000 with hormone based testing
* debate with transgender athletes

20
Q

phenotypic sex - hormones control of other hormones

A

sex hormones inhibit release of other sex hormones - hold off until puberty

inhibit anterior pituitary and hypothalamus function → reduced sensitivity to hormones enables altered state of system

activity of hypothalamus to AP is pulsatile (increases and decreases)- released GnRH to AP → leads to LH and FSH release
* increased pulsatility towards puberty → increased LH and FSH → sex hormone release
* females after puberty, changes in pulsatility of GnRH release → regulates the menstrual cycle (slow in luteal phase, increasing through follicular and pre-ovulatory stages)

21
Q

phenotypic sex - control and abnormality

A

chromosomal sex (presence//absence of SRY gene) gives rise to internal and external genitalia

abnormalities - evident at puberty - when gonads are needed to release sex hormones

under control of brain - beginning with hypothalamus

22
Q

historical perspectives of brain differences with sex (3)

A

historical view (<1990s) = sex hormones lead to differentiation of male and female brains → similar to primary and secondary sex characteristics

then suggested wider range of influences on the development of male and female brains, beyond that of the sex hormones

recently (2010+), idea of “predetermined” differences → functional significance have been challenges

23
Q

gender studied in neuroscience

A

definition is too simplistic - binary, doesn’t capture external social context for gender
WHO definition encapsulates behaviour too

neurobiological basis for gender?
* not if it is socially constructed
* but behaviour does emerge from the brain - so must be linked somehow (not just behaviour tho)
* can study relationship between biological sex and behaviour though → brain, experience, and behaviour links
* could inform understanding of gender and identity - wouldn’t give answers though

24
Q

male vs female brains - size and structure

A

male brains weigh10% more
* mostly explained by body mass differences

differences in white and grey matter

some differing structures → uncertain how these came about
differing functions are unclear

plasticity of brain - susceptible to differential influences, probs occur from birth

25
Q

bad research into male/female brain differences (4)

A

motivations → they are different so brain must be too

bad design → so many areas that some are bound to be different - make enough comparisons you will find a difference

questionable comparisons → sexual dimorphism greater in one species than another

publication bias → more likely if difference is found

26
Q

why is brain sex differences relevant

A

different incidence levels in males vs females of neurological disorders
e.g. autism
unsure if sex is a determining factor or not

27
Q

view of default development of brain

A

body development - default female pattern is modified towards a male pattern by sex hormones - this is extended to the brain too

only evidence for this with hypothalamic nuclei - involved in sexual and reproductive behaviours
hormones act perinatally to drive differentiation of hypothalamic nuclei

28
Q

what could be responsible for the masc/fem of the brain (3)

A

sex hormones:
no
* if it was we would be able to see this with brain imaging studies
* would expect greater variability in male brains than female

human brain mosaic
no
* study found variation across individuals within a gender category was greater than between categories
* some features tended to be more male or female but individuals had a combination of these - not consistent to one or the other - cancels out

environmental
potentially
* brain is plastic
* differentiated from an early stage
e.g. girls vs boys toys

29
Q

is there conclusive research into difference between male and female brain?

A

no - not sexually dimorphic - indicates binary which isn’t there

  • sex only explain 1% of total variance independent of size
  • most research doesn’t differentiate between male and female brains - viewed as irrelevant difference
  • idea of connectivity differences between hemispheres - corpus callosum in men is larger but so is rest of brain so this isn’t relevant
  • function with lateral connectivity - brain size can explain differences
  • lack of cultural inclusivity in research
  • similar emotion circuits for empathy

neuroclin 1 (9 decks)

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