Sex And The Brain

Question 1

Define sex

Answer 1

Biological state of being male or female, and is determined by chromosomes, hormones and body anatomy.

Question 2

Define gender

Answer 2

Set of behaviours and attributes a culture associated with men and women.

Question 3

Define gender identity

Answer 3

Our perception of our own gender

Question 4

How many genes are in the X and Y chromosome?

Answer 4

X - 800 genes
Y - 50 genes

Question 5

What does the sex-determining region of the Y chromosome (SRY) code for?

Answer 5

Protein called testis-determining factor (TDF)

Question 6

Where is the SRY gene located?

Answer 6

Short arm of Y chromosome

Question 7

Define turner syndrome

Answer 7

Partial or complete absence of one X chromosome in a female (XO genotype)

Question 8

What are the characteristics of turner syndrome?

Answer 8

Short stature
Receding jaw
Webbed neck
Visuospatial and memory difficulties

Question 9

Define Klinefelter syndrome

Answer 9

Extra X chromosome

Question 10

How do the gonads determine sex?

Answer 10

During first 6 weeks of pregnancy, no changes but contains the Wolffian duct and Müllerian duct

Male - Wolffian duct develops into male internal reproductive system due to release of testosterone. Mullerian-inhibiting factor also produced to inhibit female organs.

Female - Müllerian duct develops and Wolffian degenerates

Question 11

Name male hormones

Answer 11

Androgens

Question 12

Name female hormones

Answer 12

Estrogens

Question 13

What is estradiol synthesised from?

Answer 13

Testosterone using aromatase

Question 14

What is the primarily responsibility of the testes?

Answer 14

Release of androgens

Question 15

What is the principal female hormone?

Answer 15

Estradiol and progesterone - secreted by ovaries

Question 16

Name the two hormones secreted by the pituitary gland for normal sexual development?

Answer 16

Luteinizing hormone (LH)

Follicle-stimulating hormone (FSH)

Question 17

Describe role of gonadotropin-releasing hormone (GnRH)

Answer 17

Causes release of LH and FSH

Question 18

What does gonadotrophins stimulate in males?

Answer 18

LH stimulates the testes to produce testosterone

FSH matures sperm cells

Question 19

What does gonadotrophins stimulate in females?

Answer 19

LH and FSH cause the secretion of estrogen from the ovaries - menstrual cycle

Question 20

State the sexual response cycle

Answer 20

Arousal
Plateau
Orgasm
Resolution

Question 21

What is the pathway from genitals to brain

Answer 21

Axons from mechanoreceptors in the pen is and clitoris collect in the dorsal roots of the sacral spinal cord. They then send branches into the dorsal horns of the cord and into the dorsal columns through which they project toward the brain

Question 22

Engorgement and erection are primarily controlled by what?

Answer 22

Axons in the parasympathetic division of the ANS

Question 23

What does parasympathetic nerve endings release during sexual arousal?

Answer 23

ACh, vasoactive intestinal, polypeptide (VIP) and nitric oxide (NO)

Cause relaxation of arteries and the spongy substance of the clitoris and penis

Question 24

What completes the sexual response cycle?

Answer 24

Sympathetic division of the ANS

Question 25

What does the sympathetic efferent axon trigger in men and women?

Answer 25

Men - emission Women - orgasm

Question 26

Define polygyny

Answer 26

Male mates with many females but the female mates with only one male for one or multiple mating seasons

Question 27

Define polyandry

Answer 27

One female mates with many males but the male mates with one female

Question 28

Define monogamy

Answer 28

Male and female forms tightly bound relationship that includes exclusive mating

Question 29

What is the difference between prairie voles and montane voles?

Answer 29

Prairie voles - monogamy Montane voles - only female looks after children

Question 30

What effects does vasopressin have on mating?

Answer 30

High = forms relationship Low/ blocked = no attachment

Question 31

How does oxytocin and vasopressin assist in parenting habits

Answer 31

High levels = more bonding

Question 32

What brain areas are activated when people see a picture of partner or children

Answer 32

Anterior cingulate cortex, caudate nucleus, striatum

Question 33

Define sexual dimorphism

Answer 33

A sex related difference in structure or behaviour

Question 34

What is the sexually dimorphic nucleus?

Answer 34

A nucleus ear the third ventricle which is 5-8 times larger in males than females

Question 35

What neurons in the pre optic area are different in men and women?

Answer 35

Interstitial nuclei of the anterior hypothalamus (INAH) Larger in men, particularly the INAH 3

Question 36

What do women tend to perform better on then men?

Answer 36

Verbal tasks Naming objects of same colour Listing words beginning with the same letter Verbal memory

Question 37

What do men outperform women in?

Answer 37

Map reading Maze learning Mathematical reasoning Mental rotation of objects

Question 38

How do steroids influence neurons?

Answer 38

1. Act quickly in altering membrane excitability, sensitivity to neurotransmitters, or neurotransmitter release. 2. Diffuse across the outer membrane and bind to specific types of of steroids receptors in the cytoplasm and nucleus

Question 39

Define organisational effect

Answer 39

The ability of a hormone to influence the prenatal development of sexual organs and the brain

Question 40

Define activational effect

Answer 40

The ability of a hormone to activate reproductive processes or behaviours in a mature organism.

Question 41

What hormone causes the changes in gene expression responsible for masculinisation?

Answer 41

Estrogen - testosterone levels lead to increase in estrogen level s

Question 42

What is a-fetoprotein?

Answer 42

A protein found in high concentrations in feral blood, binds estrogen and protects the female foetus from masculinisation.

Question 43

What happens to a mouse that lacks a-fetoprotein?

Answer 43

Sterile and do not exhibit normal sexual behaviours

Question 44

What levels of a-fetoprotein in found in Down syndrome

Answer 44

Unusually low levels

Question 45

What are prostaglandins and what is there role?

Answer 45

Compounds derived from arachidonic acid - requires cyclooxygenase (COX) for synthesis Produced after tissue damage and involved in inducing pain and fever

Question 46

What did COX inhibits do to rodents?

Answer 46

Males - Reduced copulatory behaviour as rats Females - exhibited male like copulatory behaviour. Increased masculinisation

Question 47

What is lordosis

Answer 47

Fail to elicit they typical female mating posture

Question 48

What are androgen-insensitive men?

Answer 48

Defecting androgens gene on X chromosome Look and behave like female. Undescended testes

Question 49

What is congenital adrenal hyperplasia?

Answer 49

Secrete large amounts of androgens - external genitals are intermediate between a normal clitoris and penis

Question 50

What is the role of genes?

Answer 50

Direct the development of the gonads, and the hormonal secretions of the gonads control sexual differentiation.

Question 51

What is the purpose of the fru gene in flies?

Answer 51

Presence - develops courtship behaviour in males Absence - normal female behaviour

Question 52

What happens when leptin levels rise during pregnancy?

Answer 52

Appetite and food consumption increase

Question 53

Does fatherhood change the brain in marmosets?

Answer 53

Yes Fathers - higher density of dendritic spines on pyramidal cells and more vassopressin receptors

Question 54

How does estradiol affect neurons.

Answer 54

Modulates flow of potassium ions, estradiol depolarises some neurons and cause them to fire more action potentials Increases dendritic spines

Question 55

How does estradiol affect maze runners?

Answer 55

Enhances performance hours later

Question 56

How does INAH potentially affect sexual orientation?

Answer 56

INAH 3 is half the size in gay men when compared to straight men