Module 4 - Reproductive Flashcards
1
Q
hypothalamus
A
homeostatic regulator for reproduction, stress, body temp, hunger, thirst, sleep
- neuroendocrine organ
2
Q
neuroendocrine organ
A
processes both neural and hormonal info
3
Q
neurosecretory neurones
A
- aggregated into nuclei
- possess long axon tracts that lead into posterior pituitary
4
Q
posterior pituitary - neurosecretory peptide hormones
A
synthesised in hypothalamus -> bind to carrier proteins -> travel down to axon terminals -> stored as secretory vesicles (in posterior pituitary)
nerve impulse -> trigger exocytosis of secretory vesicles -> peptide hormone release
5
Q
posterior pituitary hormones released
A
oxytocin, antidiuretic hormone (ADH) / vasopressin
6
Q
oxytocin
A
- major effects on smooth muscle contraction (e.g milk ejection, uterus contraction during childbirth)
- secretion in response to stimulation of nipples / uterus distension
- used to induce labour
7
Q
anterior pituitary - releasing/inhibiting hormones
A
- synthesised by neurosecretory neurones in their cell body -> vesicles -> axon terminus
- nerve impulse -> hormones secreted into linking hypophyseal portal vessels
- act on specific anterior pituitary secretory cells arranged in clumps at termini of portal vessel
8
Q
anterior pituitary hormones released
A
gonadotrophs:
- follicle stimulating hormone (FSH)
- luteinising hormone (LH)
9
Q
FSH
A
- act on ovaries to stimulate growth/development of gametes
- act on testes to stimulate production of gametes
10
Q
LH
A
- act on testes to promote synthesis of testosterone
- act on ovaries to trigger ovulation and promote synthesis/release of ovarian hormones
11
Q
reproductive hormones - water soluble
A
peptides and proteins
- gonadotrophin releasing hormone (GnRH)
- follicle-stimulating hormone
- luteinising hormone
- oxytocin
12
Q
GnRH site of secretion
A
hypothalamus
13
Q
FSH site of secretion
A
anterior pituitary
14
Q
LH site of secretion
A
anterior pituitary
15
Q
oxytocin site of secretion
A
posterior pituitary
16
Q
reproductive hormones - lipid soluble
A
steroid hormones
- androgens
- oestrogens
- progestagens
17
Q
androgen site of secretion
A
testes
18
Q
oestrogens site of secretion
A
ovary
19
Q
progestagens site of secretion
A
ovary
20
Q
hormone regulation
A
by homeostatic mechanisms involving positive and negative feedback loops
21
Q
pulsatile release
A
hypothalamic secretions released in discrete bursts separated by period of little/no secretion
- prevents receptor desensitisation/downregulation
22
Q
endocrine relationships
A
complex systems of amplification controlled by a series of feedback loops
23
Q
-ve feedback control often involves
A
signalling between hypothalamus, pituitary, target organ
24
Q
ovaries function
A
- oogenesis
- regulation of menstrual cycle
25
testes function
sperm maturation
26
two main functions of gonads
1) gametes
2) reproductive hormones
27
reproductive hormones function
- begin process of sexual development
- reinitiation of puberty
28
regulation of pituitary secretory cells (GnRH feedback loop)
hypothalamus: GnRH -> anterior pituitary: gonadotrophs -> FSH and LH -> gonads: sex hormones -> -ve feedback to both hypothalamus and anterior pituitary
29
sex steroids
- androgens
- oestrogens
- progestagens
30
androgen types
- testosterone
- 5 alpha dihydrotestosterone
31
testosterone
- main secretory product of testis
- associated with development/maintenance of male characteristics/fertility
=> sertoli cells, DHT, secondary sexual characteristics
32
5 alpha dihydrotestosterone (DHT)
- more active than testosterone
- stronger (twice as potent) variant of testosterone
- important in development of secondary sexual characteristics
33
androgen key properties
- male sex development
- spermatogenesis
- sexual behaviour
- muscle development
34
oestrogen types
- oestradiol
- oestrone
- oestriol
35
oestradiol
most potent
36
oestrone
- main source of oestrogen for males
- important after menopause
- produced by adipose tissue
- weakest type of oestrogen
37
oestriol
- weaker
- softens cervix for labour
- produced by placenta prior to labour
38
oestrogen main role
development/maintenance of female characteristics/fertility
39
oestrogen main site of production
granulosa cells of growing follicle
40
oestrogen key properties
- important in both females and males (females just produce more)
- female sex development (not as much in males)
- regulation of menstrual cycle
- growth of endometrium
41
endometrium
lining of uterus
- important for implantation of fertilised embryo
42
progestagen type
progesterone
43
progesterone
- major steroidal hormone of corpus luteum/placenta
- only in females
- associated with prep/maintenance of pregnancy
- produced only during menstrual cycle
44
sex determination - bipotential
commitment of bipotential gonad to a testis or an ovary (mesoderm -> bipotential gonad -> testis/ovary)
- early gonad has potential to become both male/female
- once decision made, testes/ovary produces applicable sex hormones
45
sex determination - control
genetically controlled in mammals
- other by temp, behaviour etc.
46
sex-determining region (SRY gene)
- on Y chromosome
- provides pathway for testes to develop
- presence of testis determines sexual fate of embryo against basic feminine trend
- absence/mutation in SRY => embryo develops into female
47
sex differentiation
phenotypic development of genital structures due to action of hormones produced by gonad
48
internal genitalia
- mullerian duct: female
- wolffian duct: male
49
testis =>
- sertoli cells
- leydig cells
50
sertoli cells =>
anti-mullerian hormone -> mullerian duct regression
51
leydig cells =>
testosterone -> wolffian duct development -> internal male genitals
52
internal male genitals
- vas deferens
- seminal vesicle
- epididymis
53
ovary =>
oestrogens, progestagens
mullerian duct development -> internal female genitals
wolffian duct regression
54
internal female genitals
- fallopian tube
- uterus
- upper third vagina
55
female differentiation
- 10 weeks: wolffian duct begins to regress slowly
- mullerian ducts persist/develop to give rise to uterine (fallopian) tubes, uterus, cervix, upper vagina
56
male differentiation - testes
testis descends from internal position to scrotum usually after 7th month of pregnancy
- if not, infertile but can manually/chemically make them drop
57
external genitalia - female differentiation - labioscrotal swellings
urethral folds/labioscrotal swellings remain separate => labia minora and majora formed (respectively) which protect opening of urethra/vagina
58
external genitalia - male differentiation - labioscrotal swellings
labioscrotal swellings fuse in the midline => scrotum formed
59
external genitalia - female differentiation - genital tubercle
genital tubercle (glans area) forms clitoris
60
external genitalia - male differentiation - genital tubercle
genital tubercle (glans area) expands forming glans penis
61
external genitalia - male differentiation - urethral folds
fusion of urethral folds => urethral tube enclosed => shaft of penis formed
62
androgen insensitivity syndrome
mutation in androgen receptor gene
=> prevents androgen function
=> external genitalia appear female
=> XY/has testes but genital ducts and/or external genitals are female
63
puberty
physical, emotional, sexual transition from childhood -> adulthood
- transition is gradual and punctuated by well-defined events/milestones
64
rewakening of reproductive system =>
full secondary sexual maturation with capacity for reproduction
65
plasma levels of gonadotrophins
very low in childhood until initiation of events leading to puberty (first endocrine sign of puberty)
66
increased GnRH release =>
increased plasma levels of LH => increased sex steroids
67
plasma gonadotrophin levels - early puberty
both LH/FSH secretion occurs at night during sleep
68
plasma gonadotrophin levels - late puberty
daytime LH pulses increase
69
secondary sexual characteristics
- characteristics develop at different chronological ages in different individuals
- sequence of change occurrence is characteristic for each sex
- males: enlargement of male sex organs, aggressiveness, libedo, hair growth, baldness
70
tanner stages
- criteria for staging development of secondary sexual characteristics
- allows abnormalities to be detected
- allows comparisons to be made between individuals
71
secondary sexual characteristics - female order of occurrence
1) breast development
2) sexual hair development
3) growth spurt
4) menarche
72
breast development
- age ~10-11: first physical sign of secondary sexual maturation
- oestrogen secretion => appearance of breast bud => formation of breast mound
- ovulation + subsequent progesterone secretion => full breast development
73
sexual hair development
- age ~10-12: usually within 6 months of breast bud appearance
- due to exposure of hair follicles to androgens
- axillary hair follows ~1 year after pubic hair
74
growth spurt
- age ~11-12
- growth: stimulated by steroid hormones (oestrogen and androgen)
- epiphyseal closure (bony ends): stimulated by oestrogen
75
menarche + trend
- age 12-13 on average
- trend towards earlier menarche due to attainment of critical weight caused by improvements in nutrition, healthcare, social living conditions => shows sufficient storage required to sustain pregnancy/lactation
76
first ovulation
6-9 months after menarche
- positive feedback mechanisms of oestrogen (involving LH hormone) have not developed
- regular ovulatory cycles: established 1-2 years after menarche
77
secondary sexual characteristics - male order of occurrence
1) testicular enlargement
2) sexual hair growth
3) penile enlargement
4) height spurt
5) spermarche
78
testicular enlargement
- 10-13.5 years old
- first signs of secondary sexual development
- leydig cells enlarge/secrete testosterone => increased testicular size
79
sexual hair growth - males
- 6 months after beginning of testicular enlargement
- axillary hair begins ~18 months later
- facial hair later
80
penile enlargement
elongation/enlargement of penis begins within 1 year of testicular enlargement
81
spermarche
- first spermatogenesis event
- motile sperm seen in urine at ~13-14 years
- first ejaculation: soon after
- ability to produce sperm is earlier than ovulation in females
82
body shape in males/females
determined by differential effects of androgen and oestrogen
83
body shape - males
- more muscular
- heavier
84
body shape - females
- more fat (breasts, around reproductive area)
- pelvis easier for childbirth
85
precocious puberty
appearance of physical/hormonal signs of puberty before:
- 7 yrs in girls
- 9 yrs in boys
usually GnRH dependent problem
often extreme cases due to hypothalamic tumour
86
delayed puberty
lack of appearance of physical/hormonal signs of puberty:
~13 yrs in girls
~14 yrs in boys
- occurs when gonadotrophin signals from pituitary are inadequate for sex steroid hormone secretion
- more common in boys than girls
87
menopause
- consequence of ovaries running out of follicles that respond to hormonal stimulation
- occurs between 50-52 yrs of age
- last episode of natural menstrual bleeding signifies end of reproductive life (post menopause > reproductive life)
88
number of follicles by age
- fetal development: ~7 million follicles develop
- birth: number of follicles declined to ~1-2 million
- steady decline in follicles
- puberty: ~400 000
- menopause: < 1000 follicles
400 oocytes released throughout lifetime
89
pre-menopause
age ~40 years to end of regular cycles (~46 years)
90
menopausal transition
end of regular cycles (~46 years) to menopause (~50-52 years)
- of variable duration (tend to be longer)
- typically 4-5 years
91
peri-menopause
- around time of menopause
- many symptoms occur here
92
post-menopause
after menopause (~50-52 years) - viewed retrospectively
93
ovarian senescence
- takes 1-2 years as even without eggs, still produce hormones
- ovary essentially ceased producing hormones
94
postmenopausal oestrogen production
- reduces to < 1/10 of previous
- oestrogen produced now is oestrone (arises mainly from production in stromal cells of adipose tissue)
95
perimenopausal symptom features
- most women experience a variety of clinical symptoms of oestrogen deprivation
- most symptoms may be prevented/arrested by oestrogen treatment (menopausal hormone therapy)
BUT increased exposure to oestrogen is associated with risk of breast cancer/hormonal diseases
96
perimenopausal symptoms
1) vasomotor
- hot flushes
- night sweats
2) genitourinary symptoms
- vaginal dryness
3) bone metabolism
- increased risk osteoporosis
4) behavioural/psychological changes
- depression, tension, anxiety, mental confusion, libido
97
ovaries vs. testes
ovaries:
- cyclical activity from puberty to menopause
- ability to incubate foetus
- few oocytes released (~400)
- mature oocyte released every ~28 days
98
female reproductive organs
- vagina
- uterus
- uterine (fallopian) tube/oviduct
- ovaries
99
vagina
elastic muscular 7.5-9.0 cm tube extending from cervix to exterior of body
100
vagina function
- passageway for the elimination of menstrual fluid
- receive penis during sexual intercourse + hold spermatozoa before passing into uterus
- form lower portion of birth canal through which fetus passes during delivery
101
uterus
- small, pear-shaped organ
- weighs ~30-40 g
102
uterus function
- pathway for sperm transport
- provide mechanical protection, nutritional support, waste removal for developing embryo/fetus
- contractions in muscular wall (myometrium) important in ejecting fetus at time of birth
- source of menstrual fluid
103
endometrium subdivided into
1) inner functional zone (stratum functionalis)
2) outer basilar zone (stratum basalis)
104
inner functional zone (stratum functionalis)
contains most of uterine glands
105
outer basilar zone (stratum basalis)
- adjacent to myometrium
- attaches endometrium to myometrium
106
anteflexion/retroflexion
~20% women have retroflexed uterus
- may cause some pain during menstruation/intercourse
107
uterine (fallopian) tube/oviduct
- fertilisation typically occurs in ampulla
- provide rich, nutritive environment containing lipids/glycogen for spermatozoa, oocyte, developing embryo (number of different secretions)
108
fimbriae
- partially cover ovary
- draws oocyte into uterine tubes following ovulation
109
epithelium lining of uterine tube
both ciliated and nonciliated secretory columnar cells
110
mucosa of uterine tube
surrounded by concentric layers of smooth muscle
- allows movement of oocyte/embryo via peristaltic contraction
111
transport along uterine tube =
combination of ciliary movement + peristaltic contractions
112
ectopic pregnancy
when fertilised embryo is implanted in tissue other than uterine wall
- most occur in uterine tube (tubal pregnancy)
113
ectopic pregnancy risk factors
- smoking: cilia beating not as strong
- advanced maternal age
- prior tubal damage
114
ovaries
- oval, weight ~5-10 g
- often yellowish with bumps (follicles)
- comprised of 3 distinct regions
115
3 distinct regions of ovaries
1) outer ovarian cortex
2) central ovarian medulla
3) inner hilum (hilus)
116
outer ovarian cortex
- outer shell
- contain ovarian follicles
117
central ovarian medulla
- soft tissue
- consist of ovarian stroma
- consist of steroid producing cells
118
inner hilum (hilus)
- point of entry/exit for nerves/blood vessels
119
predicting fetal growth - before ultrasound
- fundal height
- top of uterus to pubic bone
- number of cm ≈ number of weeks gestation
- increased with: twins, breech birth, gestational diabetes
- decreased for: small for gestational age, intrauterine growth restriction
120
follicular development
1) primordial follicle
2) primary follicle
2.5) follicle development
3) secondary follicle
4) mature (Graafian/pre-ovulatory) follicle
121
primordial follicle
- formed by oocyte once surrounded by single layer of follicular cells which develop into granulosa cells
- sits largely dormant for up to 50 yrs
122
primary follicle
aka pre-antral follicles
- follicles grow
- flat squamous cells become cuboidal (metabolically active)
- immature primary follicles consist of only one layer of granulosa cells
- oocyte secretes glycoproteins -> forms zona pellucida
- beginning of condensation of ovarian stromal cells (thecal cells) around follicle
123
zona pellicuda
translucent acellular layer
- just protein no calcium
124
follicle development
FSH -> some follicles get layer -> produce many layers of granulosa cells surrounding oocyte
125
secondary follicle
aka antral follicles
- granulosa cells proliferate -> produce viscous follicular fluid: coalesces to form singular follicular antrum
126
corona radiata
formed from 3-4 cell thick inner layer of granulosa cells firmly attaching to zona pellucida
127
cumulus oophorus
mass of loosely associated granulosa cells
128
theca develops into
1) theca interna
- inner glandular
- highly vascular
2) theca externa
- surrounding fibrous capsule
129
mature (Graafian/pre-ovulatory) follicle
follicular antrum grows in size
- oocyte becomes suspended in fluid
- connected to rim of peripheral granulosa cells by thin stalk of cells
130
ovulation
- slow/controlled process that involves lots of hormones
- increased pressure from follicular fluid
- increasing size of follicle + position in cortex of ovarian stroma
- bulge out from ovarian surface
- follicle ruptures carrying oocyte + surrounding mass of cumulus cells
- oocyte collected by cilia on fimbria which sweep cumulus mass into uterine tube
131
corpus luteum
yellow body
- empty follicle becomes one of most important endocrine glands in the body for the embryo
- antrum breaks down
- basement membrane between granulosa/thecal layers break down
- blood vessels invade
132
luteinisation
- transformation of granulosa cells -> large lutein (yellow pigment) cells
- associated with increasing secretion of progestagens (primary progesterone in pregnancy as it's important for maintenance of endometrium)
133
corpus albicans
white body
- whitish scar tissue remaining
- absorbed back into stromal tissue of ovary over weeks-months
- if no fertilisation, cycle restarts
134
fertilisation
if oocyte fertilised + begins to divide, corpus luteum persists past normal 2 week life span
- rescued from degeneration by human chorionic gonadotropin (hCG) hormone
135
hCG
- produced by chorion of embryo beginning ~8 days after fertilisation
- presence of hCG in maternal blood/urine is an indicator of pregnancy (detected by home pregnancy tests)
136
two phases in ovarian cycle
1) follicular phase
- day 1 to ovulation
2) luteal phase
- ovulation to menstruation
137
three phases in uterine/menstrual cycle
1) menstruation (menstrual phase)
2) proliferative phase (preovulatory phase)
3) secretory phase (postovulatory phase)
138
length of menstrual cycle
average 28 days
variation in length due to:
- variable length of follicular phase (changes as women age)
- luteal phase usually 14 days
139
reason for menstrual cycle
humans are one of few animals that have it
female reproductive tract has two main functions:
- produce oocyte + reproductive hormones
- incubate embryo
140
menstruation =>
no fertile cycle
141
menstrual cycle - 1
- corpus luteum regresses
- oestrogen/progesterone levels: low
- FSH: increased
142
menstrual cycle - 2
FSH stimulation -> increased follicular growth
143
menstrual cycle - 3
~day 6-7: selection of dominant follicle from primary follicles to develop into single secondary follicle
- increased oestradiol
144
menstrual cycle - 4
oestradiol suppressed FSH (and LH) production in pituitary
145
menstrual cycle - 5
oestrogen levels rise
~day 12: oestradiol threshold concentration exceeded
- if very high oestradiol levels is maintained for ~36 hrs, temporary switch from -ve to +ve feedback effect on hypothalamus/anterior pituitary
=> 6)
146
menstrual cycle - 6
GnRH/LH secretion increased
147
menstrual cycle - 7
LH surge brings about ovulation
148
menstrual cycle - 8
corpus luteum develops progesterone increased
149
menstrual cycle - 9
elevated progesterone -> GnRH inhibition -> decreased FSH/LH (-ve feedback loop)
150
menstrual cycle - 10
demise of corpus luteum
151
seminiferous tubule of testes
- site of spermatogenesis
152
seminiferous tubule - interstitial cell
leydig cells
- produce progesterone/testosterone => located outside tubules close to blood vessels in interstition between seminiferous tubules
153
sustentacular/sertoli cell
- supporting
- create blood-testis barrier (tight junction)
- important in development of spermatocytes => close proximity to seminiferous tubules
- inside seminiferous tubules in direct contact with spermatogonia
=> sperm, androgen binding protein, inhibin
154
spermatogenesis + no. sperm produced
- only occurs after puberty (different to females who are born with)
- huge numbers of sperm produced constantly by mature male (300-600 sperm/gram of testis tissue/second ≈20,000 sperm per sec)
155
three phases of spermatogenesis
1) mitotic division: as in somatic cell
2) meiotic division: reproductive
- only in oocyte/presperm cell
3) cytodifferentiation: shape change from round to elongated sperm cell
156
testes at brith
firm with no sperm
157
spermatogenesis process
primary germ cells reactivated => spermatogonial stem cells => divide by mitosis => 1 undifferentiated daughter cell + 3 daughter cells that continue to divide by mitosis (differentiated spermatogonia) => primary spermatocytes => meiosis 1 => secondary spermatocytes => meiosis 2 => spermatids => spermiogenesis => spermatozoa
158
spermatogonia
- sit on basement membrane of seminiferous tubule
- move between adjacent sertoli to adluminal compartment of seminiferous tubules by squeezing through tight junctions
- 2n
159
primary spermatocytes
- adluminal compartment
- 2n
160
secondary spermatocytes
- n with 2 chromatids each
161
spermatids
- round cells/morphology
- begin to cytodifferentiate in adluminal compartment
162
spermiogenesis
- final process in spermatogenesis
- round spermatids differentiate shape and become spermatozoa (sperm)
163
spermiogenesis forms
- tail
- mid piece
- head
164
sperm mid piece
engine of sperm: packed with mitochondria to produce energy (help sperm swim through female reproductive system)
165
sperm head
- contains DNA
- covered by acrosome
166
acrosome
compartment filled with enzymes required for egg/zona pellucida penetration
167
residual body
- excess cytoplasm of spermatid is lost into this structure
- phagocytosed by sertoli cells after sperm leaves
168
reason for residual body
excess cytoplasm not needed as only job in sperm's life is to swim and fertilise egg => shed off for more efficient swimming
169
spermatogonia do not develop into sperm without
testosterone
170
kisspeptin
hormone
- sits on top of hypothalamus
- binds to gonadotrophin receptors
- regulates release of GnRH
171
inhibin
regulates FSH independently of LH
172
androgen binding protein
traps some testosterone inside seminiferous tubule to prevent escape (maintains high level)
- helps lipid based hormone (androgens) travel through blood
173
male infertility
- 1/6 to 1/4 couples are infertile
- have many causes
- common feature of infertile men is reduced sperm count (<20 million/ml)
174
male infertility types
- oligospermia
- azoospermia
- immotile sperm
175
oligospermia
some sperm in ejaculate (not production)
176
azoospermia
complete lack of sperm in ejaculate
177
immotile sperm
can't swim
178
cryptorchidism
absence of one or both testes from scrotum
- if testes don't descend
- one of most common anatomical anomalies
- 3% of term male babies (coming out of womb)
- cryptorchid individuals are infertile
179
male infertility alternatives
1) in vitro fertilisation (IVF)
2) IntraCytoplasmic Sperm Injection (ICSI)
180
IVF
- oocytes harvested (one per droplet) + fertilised ex vivo (in petri dish)
- requires ~50,000 motile sperm
- in vitro: cell culture outside the organism
181
ICSI
- single sperm injected directly into oocyte using microfine pipettes
- sperm doesn't need to be motile
- sperm collected by biopsy of testes can be used (sperm can be directly taken from testes)
- petri dish, oocyte held by holding pipette
182
orchidectomy
removal of a testis
183
testes location
scrotum
- testes move to scrotum from pelvis during pregnancy (in humans)
184
pathway of sperm
testes -> rete testis -> epididymis -> vas deferens - seminal vesicles - prostate -> urethra -> penis
185
epididymis structure
- comma shaped organ that runs around testicle
- as you move down from head -> tail, tubes converge into a single tube => all sperm in one tube to go into epididymis
- sperm move slowly (10-14 days) through epididymis
186
epididymis function
sperm acquires ability to:
- be motile
- fertilise by changing structure
=> biopsy of sperm from head/tail is different
reabsorbs liquid from around sperm making it more concentrated
187
how does sperm move through epididymis
sperm movement through seminiferous fluid -> epididymis is mediated by mass flow of fluid and a little peristalsis
188
vas deferens
- 45 cm long
- runs from epididymis -> up and around bladder -> down to join ejaculatory duct (passes through prostate)
- major site of sperm storage in humans (may be stored for several months)
189
accessory glands
1) seminal vesicle
2) prostate
190
seminal vesicle
secretory glands (not storage areas) that empty into ejaculatory duct
- directly after sperm is ejected from vas deferens
- washes sperm down ejaculatory duct
- seminal fluid is last component of ejaculate
191
ejaculatory duct
joins urethra at prostate
192
mucoid (sticky) substance secreted by seminal vesicle is:
- alkaline
- contains fructose: energy source for sperm to swim
- contains prostaglandins
- contains clotting proteins
193
prostaglandins
hormone that may induce smooth muscle contractions in female reproductive tract to help sperm swim/push them along the tract
194
clotting proteins in seminal fluid
- similar to proteins causing causing blood to clot
- clot keeps ejaculate in vagina during intercourse (prevents leaving)
195
prostate
- donut shaped organ about size of golf ball (urethra passes through)
- secretes prostatic fluid into urethra (and ejaculatory duct) ahead of sperm during ejaculation
196
prostatic fluid is:
- slightly acidic (pH 6.5)
- contains citrate (for ATP)
- milky colour (partly because P and Ca - insoluble in H2O)
- contains phosphate and calcium
- contains prostate specific antigen (PSA) protein + other enzymes
197
significance of acidic prostatic fluid
acidity of prostatic fluid is neutralised in semen by alkaline seminal vesicle fluid => buffer to physiological pH
198
significance of PSA
breaks down post ejaculation coagulum (clot) otherwise sperm stays trapped (can't swim)
199
urethra
- ~20 cm long
- runs from bladder -> through prostate -> end of penis
200
3 major structures of penis
1) corpora cavernosa (x2)
2) corpus spongiosum
3) penile urethra
201
corpora cavernosa
- main erectile tissue
- essentially blood vessels (blood-filled spaces)
202
corpus spongiosum
- surround penile urethra
- prevents occlusion during erection
203
penile urethra
conducts semen + urine
204
how does sperm move through male reproductive systm
pushed through by fluid (do not swim)
205
erection
sexual stimulation => activation of parasympathetic autonomic nervous system => release of vasodilators: nitric oxide (NO) / prostaglandin E1 => Guanosine Monophosphate (cGMP) pathway => reduced intracellular calcium => smooth muscle relaxation in corpora cavernosa => blood fills cavernous spaces more easily (engorgement) => occludes blood drainage => reduces venous outflow => adds to engorgement
206
blood volume of erect vs flaccid penis
erect penis has 8 times increased blood volume as flaccid penis
207
no bones in human penis =>
erection caused entirely by hydrostatic/hydronamic pressure in the two corpora chambers within penis
208
viagra - sildenafil
inhibits phosphodiesterase type 5 (PDE5) => increased cGMP => relaxation of arteries supplying corpora cavernosa/erection => erection
209
PDE5
enzyme that breaks down cGMP
210
semen
ejaculated fluid
211
semen composition by volume
seminal vesicle fluid: 60%
prostate fluid: 30%
sperm: 10%
other secretions: small amounts
212
semen components order of secretion
prostate fluid -> sperm -> seminal fluid
- all empty content into ejaculatory duct
213
semen pH
~7.5
214
semen total volume
2-5 mls in humans
- varies greatly in volume/content between species (e.g boar ejaculate: 500 mls)
215
semen sperm content
at least 20 million sperm/ml
216
benign prostatic hyperplasia (BPH)
not cancerous prostate overgrowth
217
BPH consequences
excess growth of prostate => occludes urethra (prostate can't grow/expand outwards due to surrounding tissue => grows inwards into urethra) => difficulty voiding bladder => eventually weakens bladder => urinary infections + ascending infection => kidney problems
218
incidence of men requiring treatment for BPH
<40: rare
50-59: 17%
60-69: 27%
70-79: 35%
>85: 90% => very common disease
219
BPH treatment options
- selective 5 alpha-reductase inhibitor(s) => stops prostate enlargement/cause shrinking
- surgery
- others
220
selective 5 alpha-reductase inhibitor(s)
- finasteride: short half life of 5-7 hrs
- dutasteride: long half life of 5 weeks
221
5 alpha-reductase
converts testosterone -> dihydrotestosterone (DHT)
222
prostate cancer
detection increasing due to PSA testing but deaths also increasing
223
PSA testing
men can be screened for elevated levels of PSA => early detection but also overdiagnosis
224
what to do about positive PSA screen
- prostate biopsy
- treat cancer
225
autopsy cancer
most (66% of) men who die with prostate cancer don't know they had prostate cancer
226
is it right to screen for prostate cancer considering...
high false positive PSA test results + autopsy cancer
227
prostate cancer treatment
- watchful waiting
- androgen depletion
-- 5 alpha reductase inhibitors (finasteride)
-- castration
-- inhibitors of androgen synthesis
- inhibition of testosterone action: block androgen receptor
- surgery: prostatectomy
- others
228
prostatectomy
- 1% die as a consequence of operation
- 20-80% have erectile dysfunction
- 4-21% have urinary incontinence as a result of operation
229
progesterone levels max during menstruation
late in postovulatory phase
- corpus luteum formed, increased secretion to prepare endometrium in time for arrival of fertilised ovum
230
initiation of menstruation
triggered by declining levels of progesterone
231
repair of ovary surface after ovulation
LH is responsible
232
prolactin
causes breast growth + milk production during pregnancy/after birth
- produced by anterior pituitary
233
mucus
produced by glands in cervix (lower part of uterus)
234
oestrogen in men
produced by leydig cells + germ cells
