Chapter 16 Flashcards
Where does sperm production take place
in the testes
what’s in testes?
SEMINIFEROUS TUBULES – that produce hundreds
inner lining of tubes
GERM CELLS – through meiosis, these cells produce haploid sperm cells. All four resultant cells are viable sperm cells.
SUSTENTACULAR (Sertoli or Nurse) CELLS – nourish and protect germ cells. They also secrete lubricating fluid to aid outward movement of sperm as they exit testis via efferent ductules and eventually epididymis. Also produces AMH (anti-Mullerian hormone), which regulates other hormones (e.g. testosterone, estradiol)
how does sperm production work 1(46)—meiotic division
2 (23)—-second meiotic division—4(23)—– 4 sperm
Between seminiferous tubules are clusters of endocrine cells called
INTERSTITIAL (aka ‘LEYDIG’) CELLS.
INTERSTITIAL (aka ‘LEYDIG’) CELLS. in testes secrete?
male sex hormones – ANDROGENS, the most important of which is TESTOSTERONE.
about how big are sperm?
their construction?
smallest in the body (~1/20 mm).
Simple construction: head and tail.
describe the tail of sperm
- its a flagellum-whipping motion provides motility
- base of tail contains a coiled mitochondrion to provide power for movement
head of sperm contains?
ucleus and an organelle called an ACROSOME. Acrosome contains digestive enzymes that helps sperm to penetrate egg (if present)
Seminiferous tubules lead into straight tubules, then??
into larger set of tubules called RETE TESTIS.
Rete testis ultimately drains into larger tubules called efferent ductules, which in turn drain into
EPIDIDYMIS
Epididymis includes
HEAD, BODY, and TAIL.
epididymis goes to?
DUCTUS DEFERENS.
DUCTUS DEFERENS passes up spermatic cord, and into
body through inguinal canal.
describe the location of the right and left ductus deferns?
pass cranially over ureters, then loops dorsal to them behind the urinary bladder.
As each duct passes behind (dorsal to) bladder, it has appended to it a gland called the
SEMINAL VESICLE.
ust prior to attachment of the seminal vesicle, the ductus enlarges into an
ampulla
-The ampulla is a position of sperm storage prior to ejaculation.
ductus
mesonephric duct
ampulla is
for sperm storage
how the spermatic cord loops
ventral to (“in front of”) the attachment of the ureter of the bladder.
seminal vessicle/seminal fluid
Plastered up against the dorsal side of urinary bladder.
Exocrine glands – provide secretions that make up most of seminal fluid.
Fluid lubricates path of exiting sperm.
Fluid is energy-rich (sugar rich) , providing food for sperm.
Fructose(sperm need sugar-provides them nutritition)
Secretions slightly alkaline – helps to neutralize slightly acidic environment of vagina.
PROSTAGLANDINS from seminal vessicle? exocrine
romote uterine contractions to help facilitate sperm movement up uterus into fallopian tubes.
Fibrinogen-forms a temporary clot in vagina.
whats important about the seminal vessicle-what does it lead too?
Once beyond the seminal vesicle, ductus is referred to as the ejaculatory duct. These are paired structures which empty into the prostatic urethra.
PROSTATE GLAND
what’s at it?
what is it made of?
what does it secrete?
Ejaculatory ducts come together to join the urethra within the mass of the prostate gland.
Prostate is a single, midline gland just inferior to urinary bladder.
Prostate is a mass of connective tissue, glandular tissue, and smooth muscle.
Prostate secretions:
Prostatic fluid
Clotting enzyme
profibrinolysin
BULBOURETHRAL GLANDS
secretes? location?
Pair of glands at base of prostate.
Secretions:
Alkaline mucus.
Lubricant for urethra & glans of penis.
erection is what para or symp?
explain
ARASYMPATHETIC function (S2, S3, S4) Parasympathetic function stimulates dilation of penile blood vessels – causing engorgement of penis with blood. (A muscular hydrostat). Parasympathetic action potentials also stimulate glands to secrete fluids (e.g., bulbourethral).
nerve involved in erection
nitiated by sensory stimuli, including sensations conveyed via pudendal nerves Conscious thoughts (cerebral cortex) can either stimulate or inhibit erection center in hypothalamus. Also in part a sacral reflex don’t have to go up to the brain- (spinal cord injuries do not preclude sexual activity)
prostatic/seminal fluid
make clot for fibriogen
EJACULATION is para/symp?
explain peristalsis importance
A SYMPATHETIC FUNCTION!!
Sympathetic fibers innervate smooth muscle of ductus deferens.
Produces forceful peristaltic contractions of smooth muscle of ductus deferens.
Peristalsis propels sperm and seminal fluid out distal end of urethra.
stimulate penis fluid?
from bulborterhtal-lubrication
4 important hormones in males
GONADOTROPIN RELEASING HORMONE (GnRH) – (hypothalamus) stimulates secretion of Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) from ant. pituitary .
FOLLICLE STIMULATING HORMONE (FSH) and LUTEINIZING HORMONE (LH) – both produced by anterior pituitary. Responsible for stimulating spermatogenesis and testosterone secretion.
TESTOSERONE – stimulates development of male sex organs, as well as secondary sexual characteristics. Participates in feedback loop involving GnRH. Also inhibits secretion of LH.
INHIBIN – secreted by sustentacular cells, in response to sperm production. Inhibits secretion of FSH.
MEIOSIS IN FEMALES
describe 1st meiotic division
inn females, only ONE of the resulting cells will be viable and the other three degenerate.
Before first meiotic division in females, each germinal cell remains in suspended development. (PRIMARY OOCYTE) (diploid).
1st meiotic division is not completed until puberty, when FSH triggers ovarian cycle.
After 1st meiotic division, the remaining largest cell is the SECONDARY OOCYTE (haploid).
2nd meiotic division is not completed until fertilization (haploid).
second oocyte
is the one that gets released,gets ovulated
if sperm dont get second oocyte
stops there
second oocyte then becomes
ovum
Each primary oocyte is packaged in an epithelial vesicle called a
follicle
Ovarian cycle has 2 basic stages:
F/L?
follicular phase (preovulatory phase) – development and maturation of primary oocyte into secondary oocyte within follicle. Release of secondary oocyte. Luteal phase (postovulatory phase) – degeneration of empty follicle and preparation of uterus for pregnancy.
Follicular phase: break down
PRIMORDIAL FOLLICLE – not yet growing.
PRIMARY FOLLICLE – develops granulosa & thecal cells and*( zona pellucidaaround oocyte) HOMOLOG OF NURSE CELLS
SECONDARY FOLLICLE – follicular fluid develops between inner & outer layers of follicle
TERTIARY FOLLICLE (VESICULAR OVARIAN FOLLICLE, GRAFFIAN FOLLICLE) – fluid fills the antrum surrounding bathing oocyte thats ready to ovulate, and primary oocyte matures into secondary oocyte, almost ready to be released.
Luteal phase:
CORPUS LUTEUM – what is left of follicle after ovulation. Corpus luteum secretes some ESTROGEN and mostly PROGESTERONE, both of which are important in regulating female menstrual cycle.
white body CORPUS ALBICANS – degenerated follicle “scar”
granulosa cells
create a bigger oocyte
OVULATION is the
where is it going to go?
released from?
elease of a secondary oocyte from a mature follicle.
occurs in response to high concentrations of Gonadotropins, primarily LH.
Secondary oocyte is “ejected” from ovary directly through mass of ovarian wall.
Fimbria directs oocyte into fallopian tube, preventing movement into COELOM
could implant in the coelom-guts
need blood supply
FSH target cells are the
granulosa cells
secrete estrogen
HYPOTHALAMUS RELEASES GONADOTROPIN-RELEASING HORMONE (GnRH). stimulates?
This stimulates the anterior pituitary to release FSH and LH.
estrogen means endometrium
builds up again
mature oocyte-granula cells
high levels, estorgen
FSH STIMULATES MATURATION OF
primary follicle
ATURING FOLLICLE SECRETES ESTROGEN AND INHIBIN. Developing follicles secrete slowly increasing amounts of
estrogen & inhibin. Eventually, inhibin will affect FSH levels.
MATURING FOLLICLE SECRETES ESTROGEN describe at low levels and at when it builds
Estrogen: (A) at low levels, inhibits secretion of LH; (B) as it increases, builds the uterine wall (endometrium).
RISING LEVELS OF INHIBIN DECREASE FSH LEVELS. what does this mean?
This dip in FSH levels, separates the dominant follicle from the rest.
HIGH CONCENTRATION OF ESTROGEN LEADS TO INCREASE IN LH SECRETION
There is a change in GnRH pulse rate and the effect on LH is reversed.
HIGH LEVELS OF ESTROGEN STIMULATE SECRETION OF LH BY ANTERIOR PITUITARY. Spike in
LH causes maturation of primary oocyte & ovulation of the secondary oocyte – leaving follicle without egg (the corpus luteum). (Approximately day 15.)
CORPUS LUTEUM SECRETES ESTROGEN AND PROGESTERONE.
This maintains the endometrium for 15-16 days and inhibits FSH & LH.
really high levels of estrogen
high levels of LH
pike in LH causes maturation of primary oocyte & ovulation of the secondary oocyte
ovulations occurs
because of high LH levels
HIGH PROGESTERONE LEVELS DECREASE GnRH PULSE RATE.
This change in pulse rate, coupled with inhibin secretion, keeps Gonadotropin levels low
-wait FSH and LH are low not maturing more oocytes at this time- no fertilzation of a zygote then corpus litum becomes albugen stops producing estrogen and progesterone-endomentrium dies- withugh GnRH raises goes back to 16-24 FSH goes back up again
(If oocyte is not fertilized and implanted in the uterine wall) what happens?
CORPUS DEGENERATES (TO CORPUS ALBICANS) AND STOPS PRODUCING ESTROGEN AND PROGESTERONE.
DECREASE IN PROGESTERONE AND ESTROGEN leads to? in terms of the cycle
ow Progesterone & Estrogen levels allow GnRH pulse rate to slightly increase. This allows an increase in FSH secretion by pituitary again. The cycle is ready to repeat.
WITHOUT ESTROGEN AND PROGESTERONE, ENDOMETRIUM BREAKS DOWN – MENSTRUATION OCCURS.what is menstration?
Menstruation is the sloughing off of the enlarged endometrial wall along with blood and mucous. This physical event marks the beginning of the cycle.
SPERM STORAGE AND FERTILIZATION
sperm can be stored?
what is point of ovulation
potential for fertilization is high when?
Females can store sperm for about four days.
(Also, it turns out that unused oocytes are actively scavenged.)
With sex before ovulation, sperm can be stored for use. So, even though ovulation hasn’t occurred, pregnancy can occur because the female is holding on to the sperm.
From point of ovulation (about day 15) to the point where the corpus luteum begins to degenerate (about day 25), fertilization can take place.
The potential for fertilization is highest during the first three days of this 10-day period.
conditions to get pregnant opportunity
HIGH LEVELS OF ESTROGEN STIMULATE SECRETION OF LH BY ANTERIOR PITUITARY. Spike in LH causes maturation of primary oocyte & ovulation of the secondary oocyte – leaving follicle without egg (the corpus luteum). (Approximately day 15.)
And
(If oocyte is not fertilized and implanted in the uterine wall) CORPUS DEGENERATES (TO CORPUS ALBICANS) AND STOPS PRODUCING ESTROGEN AND PROGESTERONE.
describe hormonal process in preggos
Developing embryo has extra-embryonic membranes: chorion, amnion, yolk sac, and allantois.
Chorion is the embryonic contribution to placenta.
Chorionic portion secretes HUMAN CHORIONIC GONADOTROPIN (hCG).
hCG prevents corpus luteum from degenerating – thus it continues to secrete PROGESTERONE AND ESTROGEN.
This maintains integrity of uterine wall and inhibits subsequent ovulation (due to lack of FSH or LH).
hormonal birth control?
Hormonal birth-control mimics these high estrogen & progesterone levels to trick the body into thinking it is pregnant and thus inhibiting ovulation.
