Chapter 18 - The Reproductive System Flashcards
1
Q
What are the primary reproductive organs in males?
A
pair of testes
2
Q
What are the primary reproductive organs in females?
A
pair of ovaries
3
Q
What are the functions of testes?
A
-producing sperm
-secreting testosterone
4
Q
What are the functions of ovaries?
A
-egg production
-secreting estrogen and progesterone
5
Q
What does the reproductive tract do?
A
-transport or house gametes after they are produced
6
Q
What do accessory sex glands do?
A
-empty supportive secretions into the reproductive tract
7
Q
Are the female breasts considered accessory sex organs?
A
yes
8
Q
What are secondary sex characteristics?
A
-external characteristics not directly involved in reproduction
-ie. body configuration and hair
9
Q
What is the male secondary sex hormone?
A
testosterone
10
Q
What is the female secondary sex hormone?
A
estrogen
11
Q
What are the male accessory sex glands? What do they do?
A
-seminal vesicles, prostate gland, bulbourethral glands
-secretions provide the bulk of sperm
12
Q
How many chromosomes do body (somatic) cells have?
A
46 chromosomes (23 homologous pairs)
13
Q
How many chromosomes do gametes (sperm/egg) have?
A
23 chromosomes
14
Q
How is gametogenesis accomplished?
A
meiosis
15
Q
Gamete chromosomes have 22 pairs of a________ and 1 pair of sex __________
A
-autosomes (code for human characteristics)
-sex chromosomes (x or y)
16
Q
Meiosis produces a ______ set of genetic information
A
half
17
Q
What is fertilization?
A
joining of male and female haploid gametes to create a diploid ovum
18
Q
How many daughter cells are produced in gametogenesis?
A
four, each with a half set of genetic information
19
Q
Where do testes produce sperm?
A
in seminiferous tubules
20
Q
Which cells produce testosterone in the testes?
A
Leydig (interstitial) cells
21
Q
Where do interstitial cells lie?
A
in the connective tissue between seminiferous tubules
22
Q
What do sertoli cells provide?
A
support for sperm
23
Q
Testosterone is a s_______ hormone derived from c________.
A
steroid; cholesterol
24
Q
What is the result of spermatogenesis?
A
many highly specialized, mobile sperm
25
During spermatogenesis:
-undifferentiated diploid spermatogonia turn into haploid spermatozoa
26
When does spermatogenesis start to occur?
puberty
27
What are the 3 stages of spermatogenesis?
-mitotic proliferation
-meiosis
-packaging
28
How long does it take spermatogonia to turn into sperm?
64 days
29
How many sperm are produced per day?
30 million
30
Mitotic Proliferation of Sperm
-spermatogonium undergoes mitosis and divides into 2 identical spermatogonia
-one of the daughter cells remains in the outer edge of the seminiferous tubule to maintain germ cell line
-the other moves into the lumen to continue dividing into 4 identical primary spermatocytes
31
Meiosis of Primary Spermatocytes
-each of the 4 primary spermatocytes meiotically divides to produce 2 secondary spermatocytes each with 23 doubled chromosomes
-these 8 secondary spermatocytes undergo another meiotic division to make 16 spermatids with 24 chromosomes each
32
Packaging of Spermatids
-the haploid spermatids are packaged into functional spermatozoa
33
Spermatogenesis involves __ mitotic divisons and __ meiotic divisions
2; 2
34
What is contained in the head of a sperm?
-nucleus
-acrosome
35
Acrosome
an enzyme vesicle that caps the tip of the head used to penetrate the ovum
36
What does the mid-piece of sperm house?
mitochondria
37
What forms the acrosome?
the golgi complex and endoplasmic reticulum
38
What is the role of the tail in sperm?
mobility
39
What are the 3 functions of sertoli cells?
1. secretes fluid that flushes sperm from tubule into the epididymis
2. secrete androgen-binding protein
3. control spermatogenesis action via inhibin
40
Where is sperm stored and matured?
the epididymis
41
What does inhibin do?
-acts in a negative feedback fashion to regulate FSH secretion
42
What hormone controls spermatogenesis?
FSH
43
What does FSH act on in males?
acts on sertoli cells to stimulate spermatogenesis
44
Which hormone acts on the interstitial cells to regulate testosterone secretion?
LH
45
Which hypothalamic hormone stimulates LH and FSH secretion?
GnRH
46
What is the ductus (vas) deferens?
-tube formed by the convergence of epididymis
47
Journey of sperm:
-seminiferous tubules, epididymis, vas deferens, seminal vesicle, ejaculatory duct, prostate gland, bulbourethral gland, urethra
48
What does the seminal vesicle do?
-fructose supply for sperm nourishment
-prostaglandin secretion for motility
-precursors for semen clotting
49
What provides the 'bulk' of semen?
seminal vesicle
50
What does the prostate gland do?
-alkaline fluid for vaginal acid neutralization
-triggers sperm clotting
51
What does the bulbourethral gland secrete?
mucus for lubrication
52
What does estrogen do?
-egg maturation and release
-secondary sex characteristics
-sperm transport in the vagina
-breast development when pregnant
53
What does progesterone do?
-suitable environment for embryo development
-ability to produce milk
54
Oogenesis is the same as ______________ in males
spermatogenesis
55
Are the steps in oogenesis and spermatogenesis the same?
yes
56
What is the difference between oogenesis and spermatogenesis?
timing and end result
57
When does oogenesis begin to occur? How often?
-at puberty
-one primary oocyte reaches maturity and is ovulated once a month until menopause
58
When does the first meiotic oogenesis division occur?
just prior to ovulation
59
When does the second meiotic oogenesis division occur?
after fertilization
60
What are oogonia?
undifferentiated germ cells in fetal ovaries
61
How do oogonia divide?
mitosis
62
By the 5th month of gestation, how many oogonia does the fetus have?
6-7 million
63
When do oogonia complete the first steps of meiotic division?
last part of fetal life (not complete meiosis)
64
How many chromosomes do primary oocytes have?
46
65
What is meiotic arrest?
-the state primary oocytes remain in for years in preparation for ovulation
66
What type of cells surround the primary oocyte?
granulosa cells
67
Primary oocyte + granulose cells = __________
primordial follicle
68
What are the 2 possible fates of a primordial follicle?
A) reach maturity and ovulate
B) degenerate to form scar tissue (atresia)
69
How many primordial follicles reach maturity in a reproductive life?
~400
70
What are antral (secondary follicles)
-the development of follicles on cyclical basis between puberty and menopause
71
How many oocytes per cycle develop?
usually only one, sometimes more
72
What is the form of the oocyte that is ovulated?
secondary oocyte
73
Spermatogenesis takes 64 days, how long does oogenesis take?
anywhere from 12-50 years (onset of puberty till menopause)
74
Do males ever run out of sperm supply?
-usually no
-even post pubertal males can produce millions of sperm each day
75
Do females ever run out of egg supply?
-yes
-females are born with an un-renewable egg supply
76
T/F: The four resulting sperm are all equally viable?
true
77
T/F: The four resulting ovum are all equally viable?
false, each primary oocyte yields only one cytoplasm-rich ovum (the other 3 are cytoplasm-poor polar bodies)
78
What are the two phases of the ovarian cycle?
follicular and luteal
79
How long does the average ovarian cycle last?
28 days
80
Follicular Phase
maturing follicles
81
Luteal Phase
presence of corpus luteum
82
Is the follicular phase the first or last half of the cycle?
first
83
What secretes estrogen during the follicular phase?
granulosa cells
84
What happens at ~day 14 during follicular phase?
-Ovulation; follicle matures and ruptures to release oocyte from the ovary
85
Where does the released oocyte go to possibly be fertilized?
oviduct
86
When does the luteal phase start?
after ovulation
87
What do the old follicular cells become?
the corpus luteum
88
How many days after ovulation does the corpus luteum become functional?
4 days
89
What does the corpus luteum secrete?
estrogen and progesterone
90
If the ovum is not fertilized what happens to the corpus luteum?
it degenerates after 14 days
91
look over major diagram
92
What hormone influences estrogen secretion?
FSH
93
FSH secretion is inhibited by
estrogen
94
Estrogen levels lower/rise as follicular phase proceeds?
lowers
95
What hormone rises in follicular phase and triggers ovulation?
LH
96
Does the LH surge result due to a positive or negative feed back loop?
positive-feedback loop
97
*** slide 61 confirm: What is the role of progesterone during the luteal phase?
inhibits FSH and LH release
98
**** What causes the corpus luteum to degenerate?
low LH
99
The rise of what hormone initiates a new cycle (mature of a new follicle)?
FSH
100
Can estrogen alone inhibit LH secretion?
no
101
The LH surge is caused by positive feedback of e_______.
estrogen
102
The LH surge does what?
1. halts follicular cell estrogen synthesis
2. reinitiates meiosis (completion of meiosis I)
3. turns follicular cells into luteal cells
103
What is the dominant feedback loop during the luteal phase?
-progesterone negative feedback on GnRH and LH
104
Which hormone maintains the corpus luteum?
LH; stimulates ongoing e and p secretion
105
What influences estrogen and progesterone secretion by the corpus luteum?
LH
106
Is progesterone or estrogen more abundant during luteal phase?
progesterone
107
What characterizes the menstrual phase?
-discharge of blood and endometrial debris
108
The 1st day of menstruation signifies what?
the start of a new ovarian cycle
109
When is uterine prostaglandin secreted?
menstrual phase
110
What does uterine prostaglandin do?
-vasoconstriction of endometrial vessels (death of endometrium)
-stimulates mild contractions for flow
111
What occurs during the proliferative phase?
-repair of the endometrium under influence of estrogen
112
How long does the proliferative phase last?
end of menstruation to ovulation
113
What is the secretory/progestational phase?
-after ovulation when large amounts of progesterone and estrogen are secreted
114
What does progesterone do to the endometrium?
-makes it highly vascularized
-secretes glycogen filled tissue
115
What happens if fertilization and implantation do not occur?
corpus luteum degenerates and a new follicular phase and menstrual phase begin
116
What is the optimal site of fertilization?
ampulla of oviduct
117
Fertilization must occur within __ hrs after ovulation.
24
118
How long can sperm survive?
usually 48 hour but up to 5 days in female
119
What does the sperm trigger when it reaches an ovum?
a chemical change in the surrounding membrane of the ovum
120
What does the chemical change of the ovum membrane do?
makes it impermeable to entry of any more sperm
121
What part of the sperm actually enters the ovum?
head
122
How long does it take sperm and egg nuclei to fuse?
1 hour
123
What is another name for a fertilized ovum?
zygote
124
What triggers the completion of meiosis (II)?
fertilization
125
A fertilized ovum divides __________
mitotically
126
How long does it take an ovum to become blastocyst
1 week
127
What is a blastocyst capable of?
implantation
128
What releases the enzymes necessary for implantation?
trophoblasts
129
What do implantation enzymes do?
digest endometrial tissue and release nutrients from endometrial cells
130
Does the trophoblast develop to become part of the fetus?
No, it develops into the fetal portion of the placenta
131
What part of the blastocyst becomes the fetus (inner cell mass or trophoblast)?
inner cell mass
132
After the embryo implants do the uterine lining cells regrow?
yes
133
What is the organ of exchange between maternal and fetal blood?
placenta
134
Do maternal and fetal blood mix?
no
135
What does the umbilical vein carry?
oxygen and nutrients to fetus
136
What does the umbilical artery carry?
waste and low oxygen content to placenta
137
What hormones does the placenta secrete?
-human chorionic gonadotropin (HCG)
-estrogen
-progesterone
138
What does HCG do?
-maintains the corpus luteum
-stimulates testosterone secretion in XY embryos
139
What is the role of estrogen during pregnancy?
-myometrium growth to increase uterine strength
-prepare mammary glands for lactation
140
What is the role of progesterone during pregnancy?
-suppresses uterine contractions
-cervical mucous plug
-prepare mammary glands
141
When does the placenta take over for the corpus luteum?
-last two trimesters
142
What secretes HCG before the placenta takes over?
trophoblast
143
How long is human gestational period?
~38 weeks
144
What physical changes to mom occur during gestation?
-uterine enlargement
-breast enlargement
-blood volume increases by 30%
-weight gain
-respiratory activity increases by 20%
-increased urinary output
145
What is required for parturition?
-cervical dilation
-collagen fibre breakdown
-relaxin secretion
-contractions
146
What 3 hormones are important for parturition?
-oxytocin
-estrogen
-DHEA
147
What hormone is released into fetal circulation by the placenta to increase estrogen production?
CRH
148
What is the role of estrogen during parturition?
-increased oxytocin receptors
-increased gap junctions for coordinated contractions
149
What 2 hormones contribute to cervical softening?
relaxin and prostaglandins
150
What hormone acts in a positive feedback fashion to increase uterine contractions?
oxytocin
151
What stimulates oxytocin secretion?
pressure of fetus against cervix
152
What hormones inhibit prolactin during gestation?
estrogen and progesterone
153
What does prolactin do?
stimulates milk production by alveolar epithelial cells
154
What initiates lactation?
withdrawal of e and p at parturition
155
Is prolactin a tropic hormone?
no
156
What mechanism sustains lactation?
suckling
157
What does suckling trigger the release of?
oxytocin and prolactin
158
Role of oxytocin on lactation:
squeezes secreted milk through ducts
159
Role of prolactin on lactation:
stimulates secretion of more milk to replace ejected milk
160
Oxytocin is secreted by ______ cells
myoepithelial (surround alveoli)
161
Prolactin is secreted by _______ cells
alveolar epithelial
162
Oxytocin is released by the ______ pituitary
posterior
163
Prolactin is released by the ______ pituitary
anterior
164
What hypothalamic hormones control prolactin secretion?
-prolactin releasing and inhibiting hormones (PRH or PIH)
