Lecture 1- Sex Differences

Principal cells of the nervous system (2)

Glial Cells, Neurons

What are glial cells

Cells that support/protect neurons

What are neurons

Signalling cells

What are the two types of neurons

Intracellular, intercellular

Within cell (intracellular)

Electrical signals known as action potentials

Between cell (intercellular)

Chemical messengers i.e neurontransmitters

Dendrite function

Receive messages from neurons

Soma function

cell body with nucleus (control centre)

Axon function

Carries the electrical signal

Myelin sheath function

Fat covering to speed up signal

Terminal button function

Send out the neutrotransmitters to neuron

Direction of neuron travel

Dendrites, soma, axon, terminal

Signal route

Electrical signal travels down the axon of the presynaptic neuron, causing the release of neurotransmitters at the terminal button. They float across the synaptic cleft then bind on to receptors on the post synaptic neuron. If the message is strong enough, a new electrical signal is triggered in the receiving neuron.

2 types of potentials

Excitatory post synaptic potential, inhibitory post synaptic potential

Glutatmate function

The brain’s main excitatory neurotransmitter

GABA function

The brain’s main inhibitory neurotransmitter

Monoamines examples

Dopamine, epinephrine, serotonin

Neuropeptides function

Slower, longer and more widespread effects

SRY gene

Sex determining region y gene

Where is the SRY gene found

On the y chromosone

Testis Determining Factor

If the SRY gene is present, it tells the gonads to become testes

What 2 hormones do the early testes produce

Antimullerian hormone and Androgens

Antimullerian hormone

Prevents female organs developing

Androgen function

Developes male characteristics

2 types of hormonal action

Organisational and activational

Organisational hormones

Effect remains after the hormone has been removed (usually in a sensitive period)

Activational hormone

Effect is dependent on hormone presence

What is hair growth controlled by during puberty

Androgens

What mechanism starts puberty

Developmental timing mechanism

Onset of puberty

GABA and NPY neurons stop inhibiting KNDy neurons

What do KNDy neurons send

Kisspeptin

What does kisspeptin trigger starting puberty

GnRH

What are the 2 gonadotropins (puberty hormones)

FSH and LH

What does FSH create in males

Sperm

What does FSH cause in females

Follices to ripen

What does LH cause in males

Testosterone production

What does LH cause in females

Ovulation

Where is GnRH sent from

Hypothalamus

What does GnRH tell the pituitary gland to do

Release FSH and LH

Ovulation sequence

FSH stimulates a follicle, releasing estradiol triggering a surge of LH. LH causes ovulation

What causes ovulation

A surge of LH from rising estradiol

What does the leftover follice become after ovulation

The Corpus Luteum

What makes progesterone

the corpus luteum

What is the genetic sex of someone with Androgen Insensitivity Syndrome

Male

What is AIS

Androgen receptors cannot respond to androgens, so female external develops

What are people with AIS typically raised as

Females

What is the genetic sex of people with 5 alpha reductase deficiency

Male

What is 5 alpha RD

Body cannot convert testosterone to DHT

What is DHT needed for in males

To make male external genitals

What do people with 5 alpha RD identify as

Female until puberty when testosterone rises then identify as men

What genetic sex are people with congenital adrenal hyperplasia

Female

What is CAH

Adrenal glands overproduce androgens leading to male looking genitals

What do CAH people typically identify as

MaleW

What enzyme is missing in CAH girls

21- hydroxylase

Male brain to female size

Male 10% larger

Female brains have

Thicker cortex so more grey matter

What is the most extreme sex difference

Sexual attraction

Gynophile

attracted to females

Androphile

attracted to males

What individual is the SCN larger in

Androphilic

What individual is the INAH-3 bigger in

Gynophilic

Antierior commisure (links hemispheres) is bigger in

Androphilic individuals

how many male sheep are homosexual

8%

what is smaller in homosexual male sheeps brains

Sexually dismorphic nucleus

3 correlates of embryonic T

Cognitive performance, finger ratio and lower otoacoutic emissions