Ch. 13- Hormones and sex Flashcards
Content from lectures and textbook
1
Q
What are exocrine glands?
A
- release their chemicals into ducts which carry them to target locations mostly on the surface of the body (ex. sweat glands)
2
Q
What are endocrine glands?
A
- ductless glands
- release their chemicals called hormones directly into the circulatory system
- hormone travels via circulatory system and reaches target on which it exerts its effects
3
Q
Name the 3 types of hormones
A
- amino acid derivatives
- peptides and proteins
- steroids
4
Q
Describe amino acid derivatives
A
- hormones that are synthesized in a few simple steps from an amino acid molecule
- example is epinephrine, released from adrenal medulla and is synthesized from tyrosine
5
Q
Describe peptides and protein hormones
A
- hormones that are chains of amino acids
- peptides are short chains
- proteins are long chains
6
Q
Describe steroid hormones
A
- synthesized from cholesterol (fat molecules)
- most diverse and long lasting effects on cell function
7
Q
What are the two main classes of gonadal steroids?
A
- androgens (testosterone) and estrogen (estradiol)
8
Q
Steroid hormone released from the ovaries and testes
A
- progesterone
9
Q
Primary function of adrenal cortex
A
the regulation of glucose and salt in the blood
10
Q
Why is the pituitary called the master gland
A
most of its hormones are tropic (influence the release of hormones from other glands)
11
Q
What are the two glands that make up the pituitary
A
- anterior and posterior pituitary
12
Q
Development of the posterior pituitary
A
develops from a small growth of hypothalamic tissue and dangles from the hypothalamus
13
Q
Development of the anterior pituitary
A
pituitary begins as part of same embryonic tissue that eventually develops into roof of
the mouth and pinches off and migrates upward to its position during course of dev.
- releases the tropic hormones
14
Q
Which part of the pituitary is actually ‘the master gland’
A
- the anterior pituitary because it releases the tropic hormones
15
Q
What is the major difference between the endocrine function of males and females?
A
- in male, levels of gonadal and gonadotropic hormones change from day to day
- in females, these levels fluctuate on a 28 day cycle (menstrual cycle)
- this difference is not due to the difference between male and female anterior pituitary, pattern controlled by some other part of the body
16
Q
What is the structure that controls the anterior pituitary?
A
the hypothalamus
17
Q
What are the two major hormones of the posterior pituitary
A
- vasopressin and oxytocin
18
Q
How does the hypothalamus control the posterior pituitary
A
the cell bodies in the paraventricular nuclei and supraoptic nuclei on each side of the hypothalamus synthesize the two main hormones of the posterior pituitary (V and O)
- the hormones are transported to their terminals in the posterior pituitary and are stored until arrival of action potentials that causes them to be released into the bloodstream
19
Q
Name for neurons that release hormones into general circulation
A
neurosecretory cells
20
Q
How does the hypothalamus control the anterior pituitary
A
- Harris suggested that the release of hormones from anterior pit was regulated by hormones released from hypothalamus
- hypothalamopituitary portal system: carries hormones from hypothal to anterior pitu
21
Q
What is a releasing hormone
A
- each hypothalamic hormone that stimulates the release of anterior pituitary hormones
22
Q
What is a release inhibiting hormone
A
each hormone that inhibits the release of an anterior pituitary hormone
23
Q
What did Guillemin and Schally find about hypothalamic releasing-inhibiting hormones
A
- isolated thyrotropin releasing hormone from the hypothalamus of sheep
- thyrotropin releasing hormone triggers the release of thyrotropin from anterior pitu which stimulates the release of hormones from the thyroid gland
- confirmed that hypothalamic releasing hormones control regulation of hormones from anteroir pitu
24
Q
What did Schally find with his isolation of gonadotropin releasing hormone?
A
- this releasing hormone stimulates the release of both the anterior pituitary’s gonadotropins: follicle stimulation hormone (FSH) and luteinizing hormone (LH)
- all hypothalamic releasing hormones like all tropic hormones have been proven to be peptides
25
3 kinds of signals that regulate hormone release
neural signals, hormonal signal, nonhormonal signals
26
Describe how hormones are released by neural signals
- all endocrine glands (except anterior pituitary) are regulated by signals from the nervous system
- endocrine glands located in the brain are regulated by cerebral neurons
- endocrine glands outside CNS are innervated by ANS (parasympathetic and sympathetic)
-
27
Describe how hormones are regulated by hormonal signals
- tropic hormones of anterior pituitary influence the release of hormones from other target glands
- circulating hormones provide feedback to the structures that influence their release
28
Describe how hormones are regulated by non hormonal chemicals
- glucose, calcium, sodium levels in the blood can all influence the release of hormones
29
What does pulsatile hormone release mean
- hormones tend to be released in pulses
- discharged several times per day in large surges lasting no more than a few mins
- large minute to minute fluctuations in the levels of circulating hormones
30
What is the model of gonadal endocrine regulation
- the brain controls the release of gonadotrophin releasing hormones from the hypothalamus
- hypothalamopituitary portal system carries it to the anterior pituitary
- in the AP, the gonadotrophin releasing hormones stimulates the release of gonadotropins
- the circulatory system carries the gonadotropins to the gonads
- in response, the gonads release androgens, estrogens and progestins which feed back into the pit and hyopthal
31
When does sexual differentiation begin in humans
at fertilization with the production of XX or XY zygote
32
At 6 weeks after fertilization, what gonadal structures do all features have
- all have primordial gonads
- the same regardless of the sex at this point
33
What does the cortex of the primordial gonad develop into?
- potential to develop into the ovaries
34
What does the medulla of primordial gonads develop into?
potential to develop into testes
35
What does the Sry gene on the Y chromosome do?
- triggers the synthesis of Sry protein
- causes medulla of each priordial gonad to grow and develop into testes
36
What does the absence of the Sry gene mean?
- cortical cells of the primordial gonads develop into ovaries
37
what are the 2 complete sets of internal reproductive ducts present 6 weeks after fertilization?
- Both Wolffian and Mullerian systems
38
What does the Wolffian system do
- have the capacity to develop into the male reproductive ducts (seminal vesicles and vas deferens)
39
What does the Mullerian system do
- can develop into the female ducts (uterus, vagina, fallopian tubes)
40
When does Mullerian inhibiting substance appear?
in the 3rd month of male development (testes secrete this)
41
How does testosterone affect the Wolffian system and Mullerian system
- stimulates the development of the Wolffian system
- along with Mullerian inhibiting substance, it causes the Mullerian system to degenerate and descend into the scrotum
42
What does ovariectomy mean
removal of the ovaries
43
What does orchidectomy mean
removal of the testes
44
What does the bipotential precursor show about genital development
that both male and female genitals develop from the same precursors: glans, urethral folds, lateral bodies and labioscrotal swellings
45
What does the glans become for each sex?
males: becomes the head of the penis
females: clitoris
46
what does the urethral folds become in both sexes?
M: fuse
F: labia minora
47
What do the lateral bodies become in both sexes?
M: penis shaft
F: clitoris hood
48
What does the labioscrotal swelling become in each sex?
M: scrotum
F: labia minora
49
What happens if testosterone is present or absent?
- present, male genitalia develop, absent: female genitalia develop
50
What are secondary sex characteristics?
features other than reproductive organs that differentiate sexually mature men and women
51
Puberty is associated with the release of these hormones
growth hormone, gonadotropic hormone and adrenocorticotropic hormone
52
What does the growth hormone act on?
only gland in the ant pit that acts on bone and muscle tissue directly (growth spurt)
53
In pubertal males, androgen levels are __ than estrogen levels
higher
54
what is androstenedione?
androgen released by the adrenal cortex and is responsible for the growth of pubic hair and underarm hair in females
male pubic hair patterns: triangle
female pubic hair patterns: inverted triangle
55
T or F: brains of men tend to be 15% larger than females
T
56
Pfeiffer and sex differences in brain function
- found that gonadectomizing neonatal rats of either sex caused them to develop into adults with the female cyclic pattern of gonatotropin release
- transplantation of testes into rats caused them to develop into adults with male patterns of gonadotropin release
- transplanting ovaries had no effect
- concluded that the female cycle pattern of gonadotropin release develops unless preprogrammed female cyclicality is overriden by testosterone
57
what is aromatization?
conversion of testosterone to estradiol via aromatase
58
what is the aromatizing hypothesis in brain sex differences?
- perinatal testosterone (around time of birth) does not directly masculinize the brain, but instead the brain is masculinized by estradiol that has been aromatized from testosterone
59
what is alpha fetoprotein?
- present in the blood of rats during perinatal period and deactivates circulating estradiol by binding to it
- testosterone is immune to alpha fetoprotein, can travel to the brain and convert estrogen bc this cannot cross the blood brain barrier
60
Parkinsons and ASD are more common in ___ while Alzheimers is more common in ___
Males, females
61
Pheonix et al. discovery of reproductive behaviours in lab
- discovered that perinatal injection of testosterone masculinizes and defeminizes a genetic females adult reproductive behaviour
- female rats exposed to perinatal testosterone displayed more male type mounting than females who had not been injected
62
What did Grady Pheonix and Young find about early exposure to testosterone in male rats
- lack of early exposure of male rats to testosterone both feminizes and demasculifnizes their reproductive behaviours
63
What are sexual dimorphisms
instances where a behaviour typically comes in two distinctive classes int which most ppl can be unambiguously assigned (reproduction related behaviours)
64
What did Anne S suffer from? the woman with Testes
- she was genetically male, XY
- internalized testes and no ovaries
- hormone levels more typical of a male
- suffered from complete androgen insensitivity syndrome (CAIS) which is a mutation of the androgen receptor gene that rendered all her receptors unresponsive
- during development, her body released male levels of androgens but her body could not respond to the, and her body developed as if there were no androgens released
65
The case of the little girl who grew into a boy
- suffered from andrenogenital syndrome caused by congenital adrenal hyperplasia (deficiency in the release of the hormone cortisol from the adrenal cortex)
- enlarged clitoris and partially fused labia
66
The twin who lost his penis
- penis was accidentally destroyed in circumcision
- he still grew up to be a boy despite being raised as a girl
67
Bremers study on orchidectomized inmates
- leads to a reduction in sexual interest and behaviour
68
T or F: sex drive and testosterone levels are uncorrelated in healthy men
T
69
Grunt and Young and the effects of testosterone on sex drive
- low, medium and high sex drives (guinea pigs)
- following castration, the sexual behaviour of all guinea pigs fell but recovered after testosterone injections (returned them to their baseline, still low, med and high)
-
70
What is dihydrotestosterone?
nonaromatizable androgen, restores the copulatory behaviour of castrated male primates but not in rodents
71
What is estrus in the context of female rats
a period of 12-18 hours when the female is fertile, receptive, prospective, sexually attractive
- caused by surges of estrogen and progesterone
72
T of F: female primates (humans) are the only female mammals that are motivated to copulate during periods of non fertility
T
73
What ovarian hormone is responsible for sexual desires in females
- in ovariectomized human females, estradiol supplements and testosterone reinstated their sexual desire and please
both estradiol and testosterone
74
Anabolic steroids and its effect on male and females
steroids that have anabolic (growth promoting) effects
- testosterone is one but not super effective
- lots have bad side effects
- in males. high levels of steroids reduce gonadotropin release leading to less testicular activity and they shrivel and become in fertile
- gynecomastia (breast growth in males) can also occur
- in females, it can produce amenorrhea (cessation of menstriation) and masculine like features: growth of clitoris, body hair, etc.
75
what is amenorrhea
loss of period in women
76
what is gynecomastia
growth of breast in men
77
4 brain structures with roles in sexual behaviour
cortex, hypothalamus, amygdala, ventral striatum
78
What does the cortex mediate in terms of sexual experience
- feelings of release and loss of control, changes in self awareness, disturbances of awareness of space and time, feelings of love
79
Male rat and hypothalamus and sexual activity
- Gorski discovered medial pre optic area of hypothalamus was larger in males than females
- called this the sexually dimorphic nucleus
- at birth, this was equal among male and females but grew for men later on, bc of estradiol that was aromatized
80
Female rats and the hypothalamus in sexual behaviour
- the ventromedial nuclei contain circuits that are critical for sexual behaviour
-
81
Role of amygdala in sexual behaviours
- identify partners
82
Role of ventral striatum in sexual activity
- anticipation and experience of sexual activity
83
in males, the ___ of the hypothalamus regulates sexual activity whereas in females the ___ of the hypothalamus regulates it
medial preoptic area, ventromedial nuclei
84
What is gender identity
the gender that a person identifies with
85
Describe the relationship between sexual orientation and genes
- group of gay males who had twin brothers, 52% of the monozygotic twins and 22% of the dizygotic twins were gay, similar in females
86
Fraternal birth order effect
- the probability of a man being gay increases as a function of the number of older brothers he has
87
Maternal immune hypothesis
mothers develop an immune response to masculinizing hormones from male fetuses which that a mothers immune system will suppress masculinizing effects in her younger sons
88
What triggers the development of sexual attraction
- at the age of 10 on average
- stimulated by the adrenal cortex steroids which mature around 10yrs old
89
LeVay's famous study on sexual attraction
- found that the structure of one hypothalamic nucleus in gay males was intermediate in size to that of straight female/male
