Repro Physiology Flashcards
1
Q
four functions of reproductive organs
A
- form specialized cells for sexual reproduction called gametes (sperm, ova)
- bring gametes from M + F together via sex (copulation)
- combine genetic info in gametes via fertilization (zygote = when sperm + egg fuse; first cell of new being)
- support development of fetus (gestation) and birth of baby (parturition)
2
Q
what is the HPG axis
A
Hypothalmic Piuitary Gonadal Axis
sequence of hormonal events involving hypothalamus, ant pituitary, and testes that regulates the production of gametes + sex hormones
involves: GnRH, FSH, LH, testosterone, and inhibin
3
Q
inhibin function
A
released from gonads; neg feedback on FSH release from ant pit
4
Q
how does the HPG axis activate at puberty?
A
before puberty, low levls of circulating sex hormones suppress GnRH release
closer to puberty, hypothalamus less sensition to inhibition by sex hormones > hypothalamus releases GnRH in pulse like manner
> ant pit release FSH LH > gonads release more sex hormones > cont
5
Q
what type of nuclear divison only occurs in gonads that allows sexual reproduction?
A
meiosis; reduces number of chromosomes in gametes by half so zygote doesnt end up with twice as many chromosomes
2 cellular divisions, one DNA replication
6
Q
phases of meiosis I
A
prophase
metaphase
anaphase
telophase
7
Q
functions of mitosis vs meiosis
A
mitosis: ensures all body cells have same complement of DNA for normal growth and repair
meiosis:
- number of chromosomes cut in half (2n > n )
- genetic diversity
8
Q
sperm producing male gonads
A
testes
9
Q
sperm is delivered to body through…
A
system of ducts
- epididymis
- ductus deferens
- ejaculatory duct
- urethra
10
Q
haploid vs diploid
A
haploid = one chromosome from each pair (23)
diploid = two sets of chromosomes - 46
11
Q
difference between corpus cavernosum and corpus spongiosum
A
erectile tissue of penis -
cavernosum - top layer (vascularity)
spongiosum surrounds urethra - on both top and bottom (urination, ejaculation)
12
Q
scrotal muscles
A
when cold, testes pulled closer to warm body wall
- dartos muscle: smooth muscle in superficial fascia that wrinkles skin
- cremaster muscles: skeletal muscle that elevates testes
13
Q
layers of tunics surrounding testes
A
tunica vaginalis (from peritoneum) - outside layer
tunica albuginea of testes - inner layer forms fibrous capsules
14
Q
what is the site of sperm production
A
seminiferous tubules
15
Q
movement of sperm
A
seminiferous tubules > straight tubule > rete testis > efferent ductules > epididymis
16
Q
storage site of sperm
A
tail of epididymis ; mature here and are stored here until ejaculation
17
Q
blood supply to testes
A
- testicular arteries arise from abdominal aorta
- testicular veins arise from pampiniform venous plexus surrounding each test artery (cooler; absorbs heat from test art)
spermatic cord encloses nerve fibers, blood vessels, and lymphatics that supply testes
18
Q
what are the accessory ducts? what is their purpose?
A
carry sperm from testes to body exterior:
- epididymis
- ductus deferens
- ejaculatory duct
- urethra
19
Q
explain the microscopic anatomy of the epididymis
A
- head: contains efferent ductules that empty into highly coiled duct of the epididymis
- body and tail make up remainder of duct of epididymus (20 ft in length)
- pseudostratified epithelial cells of duct mucosa contain microvilla (stereocilia) - large SA allows absorption of excess testicular fluid and pass nutrients to stored sperm
20
Q
sperm movement through and past epididymis
A
takes 20 days for nonmotile sperm to slowly pass through epididymis (can be stored several months)
during ejaculation, epididymis contracts and expels sperm into ductus deferens
21
Q
anatomy of ductus (vas) deferns
A
- passes through inguinal canal to pelvic cavity
- expands to form ampulla
- joins duct of seminal vesicle to form ejaculatory duct
smooth muscle in wall propels sperm from epididymis to urethra
22
Q
what happens during a vasectomy? why is this effective?
A
cutting and ligation of ductus (vas) defernens; this is part of ejaculatory duct and what propels sperm from epididymis to urethra
23
Q
urethra (male) anatomy and function
A
carries urine and semen
has three regions
- prostatic urethra (surrounded by prostate)
- intermediate (membranous) urethra: in urogenital diaphragm
- spongy urethra: runs through penis in corpus spongiosum; opens at external urethral orifice
24
Q
A
25
internal anatomy of penis
made up of pongy urethra and three cylindrical bodies of erejtile tissue
- corpus spongiosum - spongy CT that surrounds urethra and forms glans and bulb of penis
- corpus cavernosa: paired dorsal erectile bodies; smooth muscle with vascular spaces
26
male perineum anatomy and function
- suspends scrotum
- contains root of penis and anus
27
anatomy of seminal glands/vesicles
on posterior bladder surface
duct of seminal gland joins ductus deferens to form ejaculatory duct
contains smooth muscle that contracts during ejaculation
28
function of seminal glands/vesicles
produces viscous alkaline seminal fluid
- fructose, citric acid, coagulating enzyme (vesiculase), prostaglandins
- yellow pigment UV reactive
- 70% semen volume
29
prostate anatomy
- encircles urethra inferior to bladder
- size of peach pit
- smooth muscle that contracts during ejaculation
30
prostate function
secretes milky, slightly acid fluid
- contains citrate, enzymes, and PSA
- role in sperm activation
- enters prostatic urethra during ejaculation
- 1/3 of semen volume
31
bulbo-urethral gland anatomy
pea sized glands inferior to prostate
32
bulbo-urethral gland function
produce thick, clear mucus during sexual arousal
- lubricate glans penis
- neutralize traces of acidic urine in urethra
33
general make-up and function of semen
- milky white mixture of sperm and accessory gland secretions
- **contains fructose for ATP production**, protects and activates sperm, facilitates sperm movement
- alkaline fluid neutralizes acidity of male urethra and female vagina and enhances motility
34
physiology of erection
arterioles are normally constricted
sexual excitement > CNS activation of PS neurons innervating internal pudendal arteries
> local release of nitric oxide > relaxation of local vascular smooth muscle > dilation of arterioles
> corpus cavernosa expands and slows venous drainage > engorgement of ereticle tissues with blood > erection
35
components of semen and their function
- PGs: dec viscosity of cervical mucus, stim reverse peristalsis in uterus
- relaxin (hormone) > enhance sperm motility
- ATP for energy
- suppress female immune response
- antibiotic chemicals destroy some bacteria
- clotting factors coagulate semen initially to prevent draining out, then liquefy it with fibrinolysin so sperm can finish journey
36
erection and ejaculation
parasympathetic or sympathetic?
erection: PS
ejaculation: sympathetic
37
what is responsible for keeping the male urethra open during erection
corpus spongiosum
38
physiology of ejaculation
spinal reflex initated over sympathetic nerves resulting in:
ductus deferens, prostate, seminal glands contract and empty into prostatic urethra
(bladder internal sphincter constricts to prevent urine expulsion or semen reflux into bladder)
semen in urethra triggers spinal reflex via somatic neurons
- bulbospongiosus muscles have rapid series of contractions > expulsion
39
where does speratogenesis occur? at what time?
- occurs in seminiferous tubules at puberty (~14)
40
histology of seminiferous tubules
thick stratified epithelium surrounding a central fluid filled lumen with four types of cells:
- sustenocytes
- spermatogenic cells
- myoid cells
- interstitial endocrine cells (Leydig cells)
41
what are sustenocytes (sertoli cells)
large columnar cells of the seminiferous tubules that extend from the basal lamina to tubule lumen and act as supporting cells and play a role in sperm formation
42
what are spermatogenic cells
cells of the seminiferous tubules that are surrounded by sustenocytes and are the main cells that give rise to sperm
43
what are myoid cells
smooth muscle-like cells surrounding seminiferous tubules that contract to squeeze sperm and testicular fluid through tubules
44
what are interstitial endocrine (Leydig) cells
cells of the seminiferous tubules that produce androgens and some estrogen
45
steps of spermatogenesis
1. mitosis of spermatogenia (stem cell): forms 2 spermatocytes
2. meiosis: spermatocytes form secondary spermatocytes, which form spermatids
3. spermiogenesis: spermatids become sperm
46
**Spermatogenesis**: what occurs during mitosis of spermatogonia
**forming spermatocytes
at puberty, spermatogensis begins with **spermatogonia** (stem cells in direct contact with epithelial basil lamina that divide continuously by mitosis)
after pubery, each division produces:
- **Type A daughter cells**: remain at basal lamina to maintain pool of dividing germ cells
- **Type B daughter cells**: move toward lumen and develop into** primary spermatocytes**
47
**Spermatogenesis**: what occurs during meiosis
**spermatocytes to spermatids
**
**meiosis I**: primary spermatocyte (2n) undergoes meiosis I > **two secondary spermatocytes (n)**
**meiosis II**: secondary spermatocyte (n) rapidly undergoes meosis II >** two spermatids (n)**
- small round cells with large nuclei close to lumen of tubule
- nearly all genes turned off and DNA compacted into dense pellets
48
**Spermatogenesis**: what occurs during spermiogenesis
**spermatids to sperm
**
spermatids contain correct haploid chromosome number for fertilization (N); still all nonmotile
during spermiogensis, spermatid elongates, loses excess cytoplasm, and forms a tail
49
anatomy of sperm
- **head**: *genetic region* that includes nucleus and helmet-like *acrosome* containing hydrolytic enzymes that enable sperm to penetrate egg
- **midpiece**: *metabolic region* containing mitochondria that produce ATP to move tail
- **tail**: *locomotor region* that includes *flagellum*
50
how long does spermatogenesis take?
64-72 days in normal conditions
51
how do non-motile sperm enter epididymis?
pressure of testicular fluid pushes immotile sperm into epididymis, where they gain motility and fertilizing power
52
role of sustentocytes/sertoli cells
sustentocytes contain tight junctions that divide tubule into two compartments:
- **basal compartment:** basal lamina to tight junctions; spermatogonia and primary spermatocytes here
- **adluminal compartment**: internal to tight junction: meiotically active cells and tubule lumen here
separated by a **blood testis barrier**
they also:
- provide nutrients and signals to dividing cells
- move spermatocytes and spermatids to lumen
- secrete testicular fluid into lumin for sperm transport
- phagocytize faulty germ layers and excess cytoplasm
- produce mediators to regulate spermatogenesis
53
what is the function/importance of the blood testis barrier created by sustenocytes/sertoli cell in the seminiferous tubules?
prevents sperm antigens from escaping into blood and activating immune system
sperm isnt formed til pubery, and is absent during immune system development
- results in sperm not being recognized as "self"
- therefore, sperm needs to be kept separated from rest of body to avoid being attacked by immune system
54
what are mediators that regulate spermatogensis? how are they produced?
produced by sustenocytes/sertoli cells
- androgen-binding protein (ABP): keeps testosterone levels high to stim spermatogenesis
- inhibin: inhibits spermatogenesis by inhibiting FSH release from ant pit
55
what is the composition of testicular fluid
androgens and metabolic acid
56
how is the production of gametes and sex hormone in males regulated?
sequence of events involving hypothalamus, ant pit, and testes
referred to as hypothalmic-pituitary-gonadal (HPG) axis
involves interacting hormones: GnRH, FSH, LH, testosterone, inhibin
57
explain the sequence that occurs along the HPG axis when regulating testicular function
- hypothalamus releases GnRH
- GnRH binds to ant pit gonadotropic cells > release FSH and LH
- FSH indirectly stim spermatogenesis by causing sustenocytes to release ABP to keep testosterone high
- LH binds to/stimulates interstitial endocrine cells (Leydig) to stim more testosterone
- testosterone acts at other sites (stim maturation of organs, development/maintenence of sec sex characteristics, libido)
neg feedback by testosterone inhibits FSH and LH release from ant pit and GnRH release from hypothalamus
inhibin released locally by sustenocytes when sperm count is high by sustenocytes feeds back on the ant pit, dec FSH and GnRH release
58
what is testosterone synthesized from
cholesterol
59
how does testosterone transform and/or act at different sites in the body?
- converted to dihydrotestosterone (DHT) in prostate and into estradiol in some brain neurons
- prompts spermatogensis and targets accessory organs
- has multiple anabolic effects throughout body
60
what would a deficiency of testosterone lead to?
- atophy of accessory organs
- declining semen volume
- impaired erection/ejaculation
61
ligaments that hold the ovary in place
- ovarian: anchors ovary medially to uterus
- suspensory: anchors ovary laterally to pelvic wall
- mesovarium: suspends ovary
suspensory + mesovarium = part of broad ligament which supports uterine tubes, uterus, and vagina
62
blood supply for ovaries
- ovarian arteries (branches of abdominal aorta)
- ovarian branch of uterine arteries
- vessels travel through suspensory ligament and mesovaria (broad ligament)
63
ovary surrounding tissue
- each ovary surrounded by fibrous tunica albuginea, which is then covered by germinal cuboidal epithelium outer layer (continuation of peritoneum)
64
layers of ovary
- outer cortex that houses forming gametes
- inner medulla that contains large BVs and nerves
65
ovarian follicles
- tiny, sac-like structures embedded in cortex
- contain immature egg (oocyte) encased by one or more layers of diff cells
66
female duct system
uterine tube sys does not have direct contact w ovaries; ovulated oocyte released into peritoneal cavity; some never make it to tube system (can > ectopic)
tube sys includes:
- uterine tubes
- uterus
- vagina
67
uterine tubes
- AKA fallopian tubes or oviducts
- receive ovulated oocyte and are usual site of fertilization
- extends from ovary > sup uterus
68
regions of uterine tube
- infundibulum: funnel shaped opening in peritoneal cavity that has ciliated fimbriae that drape over ovary
- ampulla: forms half uterine tube length; fertilization site
- isthmus: narrow medial third that empties into superolateral region of uterus
69
uterine tube actions
- during ovulation, uterine tube captures oocyte (fimbrae stiffen and sweep ovarian surface creating current to carry oocyte into tube)
- oocyte carried along toward uterus by smooth muscle peristalsis + ciliary action
- non-ciliated cells of tube function to nourish oocyte and sperm
70
external surface uterine tubes
- covered by peritoneum
- supported by a short mesentary called mesosalpinx (also part of broad ligament)
71
parts of broad ligament
- mesosalpinx: supports uterine tubes
- mesovarium: suspends ovary
- mesometrium
72
uterus
- hollow, thick walled muscular organ
- function is to receive, retain, and nourish fertilized ovum
73
regions of the uterus
- body: major portion
- fundus: rounded sup portion
- isthmus: narrowed inf region
- cervix: narrow neck/outlet
74
cervical canal communication with uterus and vagina
cervical canal communicates with:
- vagina via external os
- uterine body via internal os
75
cervical glands function
cervical glands secrete mucus that blocks sperm entry except during midcycle
76
supports of the uterus
- mesometrium: lateral support of broad ligament
- cardinal (lateral cervical) ligaments: from cervix/sup vagina > lat pelvic walls
- uterosacral ligaments: secure uterus to sacrum
- round ligaments: bind uterus to ant wall
77
peritoneal sacs around uterus:
- vesicouterine pouch: between bladder and uterus
- rectouterine pouch: between rectum and uterus
78
layers of uterine wall
- perimetrium: outer serous layer (visceral peritoneum)
- myometrium: bulky middle layer with interlacing layers of smooth muscle (contracts during childbirth)
- endometrium: inner mucosal lining of simple columnar epithelium on top of thick lamina propria
79
where does the fertilized egg burrow into and reside during development?
endometrium
80
layers of endometrium
- stratum functionalis (functional layer): changes in response to ovarian hormone cycles, shed during menses
- stratum basalis (basal layer): forms new stratum functionalis after menses; unresponsive to ovarian hormones
81
uterine wall vascular supply
uterine arteries arise from internal iliacs and branch into:
arcuate arteries in myometrium, branch into
radial arteries in endometrium, branch into
- straight arteries in stratum basalis
- spiral arteries in stratum functionalis that degenerate and regenerate (spasms cause shedding of functionalis during menses)
82
what structure(s) can lead to prolapse of the uterus
pelvic floor muscles, not ligaments
83
what is the vaginal fornix?
upper end of vagina surrounding cervix
84
layers of vaginal wall
- fibroelastic adventitia
- smooth muscle muscularis
- stratified squamous mucosa with rugae
85
pH vaginal secretions
acidic in adults, alkaline in adolescents
86
what glands in females are homologous to bulbourethral glands in males?
greater vestibular glands; release mucus into vestibule for lubrication
87
lactation pathway
- lobules within lobes have glandular alveoli that produce milk
- milk passed into lactiferous ducts then > lactiferous sinuses that open outside at nipple
88
mammary glands are what type of glands
modified sweat glands
89
what attaches the breasts to the underlying muscle?
suspensory ligaments
90
oogenesis overview
begins in fetal peroid
- oogonia (diploid stem cells) divide by mitosis to produce
- primary oocytes that undergo meiosis I to produce
- secondary oocytes that undergo meiosis II to produce
- ova
91
main differences between oogenesis and spermatogenesis:
1. production of primary oocytes occurs only in fetus
2. in primary oocytes, meiosis is arrested in late prophase I and resumes only years later (if at all)
3. in secondary oocytes, meiosis is arrested in metaphase II and is only completed if fertilization occurs
92
ovarian follicles
functional unit of ovary that encloses a single oocyte surrounded by:
- pregranulosa cells (if single layer of cells)
- granulosa cells (if more than one layer present)
93
follicular stages of development
- primordial follicle: single layer of squamous pre-granulosa cells surrounding primary oocyte (usu stays this way til menopause)
- primary follicle: single layer cuboidal pre-granulosa cells surrounding primary oocyte
- secondary follicles: multiple layers of granulosa cells surrounding primary oocyte
- vesicular (antral) follicles/tertiary: have fluid filled cavity called an antrum (before ovulation, primary oocyte inside vesicular follicle resumes meiosis and becomes secondary oocyte)
94
what is atresia?
apoptosis of oocyte and surrounding cells
95
dominant follicle resumes meiosis I when?
just before ovulation
after division completed, two haploid cells are produced:
- first polar body: smaller cell, no cytoplasm
- secondary oocyte: large cell with almost all of mother cell cytoplasm and organelles
96
what happens to the secondary oocyte arrested in metaphase II?
it will be the ovulated ovum
- if not penetrated by sperm > deteriorates
- if penetrated, completes meiosis II, yielding
1. an ovum with large cytoplasm to nourish fertilized egg for 6-7 day journey to uterus
2. second polar body - small cell, no cytoplasm, degenerates and dies
97
oogenesis vs spermatogenesis: number of functional gametes
- oogenesis: one viable haploid ovum with 2-3 haploid polar bodies
- spermatogenesis: four viable sperm
98
oogenesis vs spermatogenesis: timing
- O; begins in fetal life, ends in menopause
- S: begins in puberty > old age
99
oogenesis vs spermatogenesis: error rates
- O: 20%
- S: 3-4%
100
oogenesis vs spermatogenesis: time to produce one gamete
- O: 13-50 yr
- S: 74 days
101
oogenesis vs spermatogenesis: supporting cells
O: many granulosa cells sustain one oocyte
S: one sustenocyte sustains many spermatocytes
102
maturation of follicles phases
1. Pre-antral phase: gonadotropin independent, involves intrafollicular paracrines
2. antral phase, stim by FSH and LH (dom follicle selected, primary oocyte resumes meiosis I)
103
role of thecal cells in follicle development
during process of primary follicle > secondary follicle
CT and granulosa cells condense to form theca folliculi; thecal cells secrete hormone in response to LH
104
what distinguises the vesicular follicle from previous follicles?
antrum; all fluid has coalesced
105
what is mittelschmerz
ovulation pain
106
identical vs fraternal twins production
if an ovulation releases more than one secondary oocyte that gets fertilized > fraternal
identical twins are from fertilization of one oocyte, then separation of daughter cells
107
what hormones does the corpus luteum secrete
progesterone and some estrogen
if pregnancy occurs, secretes these til 3 months to sustain til placenta takes over
108
if no pregnancy occurs, corpus luteum degerates into>
corpus albicans (scar)
109
luteolytic/ischemic phase
last 2-3 days of luteal phase, when endometrium begins to erode
110
FSH and LH specific actions related to hormone secretion
- FSH: stim granulosa cells to release estrogen
- LH produces thecal cells to produce androgens, which granulosa converts to estrogens
111
negative feedback of ovarian cycle
- inc plasma estrogens inhibit FSH/LH release
- inhibin from granulosa cells inhibits FSH release
- only dominant follicle withstands dip in FSH, other follicles deteriorate
112
positive feedback of ovarian cycle
- estrogen levels cont to inc due to cont release from dominant follicle
- at critically high level, a brief pos feedback occurs on brain/ant pituitary > triggers LH surge (stim ovulation)
113
estrogen metabolic effects
- anabolic
- maintains low total blood cholesterol and high HDL levels
- facilitates Ca uptake (bone health)
- stim Na resorption by renal tubules, inhibiting diuresis
114
major source of estrogens (mainly estradiol)
ovary; developing follicles and corpus luteum
115
major source of progesterone
ovary; mainly corpus luteum
116
major source of testosterone
testes; interstitial endocrine cells
117
stimulus for release of
- estradiol
- progesterone
- testosterone
- E: FSH (and LH)
- P: LH
- T: LH
118
feedback effects exerted by estrogens
both neg and pos feedback on gonadotopin release by ant pit and GnRH release by hypothalamus
119
feedback effects exerted by progesterone
neg feedback on gonadotropin release by ant pit and GnRH release by hypothalamus
120
feedback effects exerted by testosterone
neg feedback on gonadotropin release by ant pit and GnRH release by hypothalamus
121
metabolic effects progestone
promotes diuresis
inc body temp
122
metabolic efffects testosterone
anabolic
stim hematopoieses
enhances BMR
123
