Chapter 18- The Reproductive System Flashcards
(155 cards)
1
Q
How many chromosomes are in in a human somatic cell?
A
46 (diploid)
23 homologous pairs
2
Q
How many chromosomes are in gametes (Sperm and egg)?
A
23 (haploid)
3
Q
How are gametes made?
A
Gametogenesis via meiosis
4
Q
What are autosomes?
A
22 pairs of chromosomes which code for general human characteristics and specific traits
e.g; eye colour
5
Q
What is the 23rd pair of chromosomes?
A
Sex chromosomes
2 types:
Larger X chromosome
Smaller Y chromosome
6
Q
What are the gonads of the male reproductive system called?
A
testes
7
Q
What is the dual function the testes?
A
- produce sperm
- Secrete testosterone
8
Q
Where is sperm produced within the testes?
A
Seminiferous tubules
9
Q
What cells produce testosterone?
A
Leydig interstitial cells
10
Q
Where do Leydig cells lie?
A
In connective tissue between seminiferous tubules
11
Q
What cells support spermatogenesis?
A
Sertoli cells
12
Q
What kind of hormone is testosterone?
A
Steroid hormone derived from cholesterol
13
Q
What are the 5 categories of testosterone effects?
A
Reproductive system before birth
Sex-specific tissues after birth
Other reproductive-related effects
Secondary sexual characteristics
Non-reproductive actions
14
Q
What does spermatogenesis result in?
A
Many highly specialized, mobile sperm
15
Q
What do haploid sperm start off as?
A
Undifferentiated diploid germ cells (spermatogonia)
16
Q
When do diploid germ cells differentiate into haploid spermatozoa?
A
At puberty
17
Q
What are the 3 major stages of spermatogenesis?
A
Mitotic proliferation
Meiosis
packaging
18
Q
How many days does it take to go from spermatogonia to sperm?
A
64 days
~30 million sperm/day
19
Q
What is mitotic proliferation?
A
2 mitotic division to make 4 identical primary spermatocytes
20
Q
What is meiosis?
A
2 meiotic divisions
16 sperms from each spermatogonia
21
Q
What is packaging?
A
Closely associated with Sertoli cells
Spermatozoa created
22
Q
What are the four parts of Sperm?
A
- Head
- Acrosome
- Midpiece
- Tail
23
Q
What is the head of the sperm?
A
Mostly just the nucleus which contains DNA
24
Q
What is the acrosome of the sperm?
A
Enzyme-filled vesicle that caps the tip of head
25
What is the function of the acrosome?
Enzyme used to penetrate ovum
26
What forms the acrosome?
Endoplasmic reticulum and Golgi complex before the organelles are discarded
27
What is the midpiece of the sperm?
Area where mitochondria are concentrated
28
What is the tail of the sperm?
Provides mobility for sperm
29
Where are Sertoli cells located?
Seminiferous tubules
30
What is the function of Sertoli cells?
Secrete fluid
Secrete androgen-binding protein
Site of action to control spermatogenesis
31
What does the fluid secreted from Sertoli cells do?
flushes released sperm from tubule into the epididymis for storage and maturation
32
What do Sertoli cells release to control spermatogenesis?
Inhibin
33
How do Sertoli cells regulate FSH secretion?
Negative-feedback
Inhibin: inhibits release of FSH
34
What two gonadotropic hormones from the anterior pituitary control the testes?
1. Luteinising hormone LH
2.Follicle-stimulating hormone FSH
35
What hormone is essential to maintaining spermatogenesis in adult males?
testosterone
36
What hormone directly controls testosterone?
LH
37
What hormone does testosterone feedback influence the release of?
GnRH
38
What does GnRH do?
Regulates gonadotropins
39
What hormone acts on Sertoli cells to stimulate spermatogenesis?
FSH
40
What are LH and FSH levels like pre puberty?
Too low to stimulate testosterone production
41
What age is more GnRH released?
from 8-12 years
-onset of puberty
42
What is the pathway of sperm after spermatogenesis?
Produced in seminferous tubules ---> Epididymis ---> Ductus vas deferens
43
What does testosterone do to sperm in the epididymis?
Gain motility and fertilisation
-mature
44
Where are sperm concentrated?
Ductus deferens
45
How are sperm concentrated?
Peristaltic contractions
46
How long are sperm stored for?
Several days
47
What are the primary reproductive organs of the Female reproductive system?
Ovaries
-produce ova via oogenesis
48
What do the ovaries secrete?
female sex hormones
49
What are the female sex hormones?
Estrogen
Progesterone
50
What are the undifferentiated primordial germ cells called in fetal ovaries?
Oogonia
51
What happens to oogonia?
Divide mitotically
6 mill to 7 mill oogonia by 5th month of gestation
52
What happens to Oogonia during the last part of fetal life?
The beginning of the early steps of the first meiotic division
-isn't completed tho- Primary oocyte
53
What are primary oocytes?
Oocyte with diploid number of 46 replicated chromosomes
54
What do primary oocytes remain in for years until ovulation?
Meiotic arrest
55
What are primary oocytes surrounded by?
Single layer of ganulosa cells
Oocyte + granuloma cells --> primordial follicle
56
What is a primordial follicle?
The starting point of follicular development and the basic functional unit of female reproduction
~2 million at birth
57
After development starts what are the 2 fates of a primordial follicle?
1. Reach maturity and ovulate
-become a primary follicle
~400/reproductive life
2. Degenerate to form scar tissue
-Atresia
58
What happens between puberty and menopause?
Follicles develop into secondary astral follicles on cyclic basis
-1 oocyte/cycle (normally)
59
What happens to a primary oocyte just before ovulation?
Completes first meiotic division
-First polar body (non-functional)
-Secondary oocyte is ovulated
60
What does sperm entry/fertilization trigger?
Second meiotic division of oocyte
-Second polar body (haploid, non-functional)
61
What cells unite during fertilisation?
Mature haploid ovum units with haploid sperm cell
62
How many ovum does a primary oocyte yield?
one
-3 polar bodies disintegrate
63
What is the ovarian cycle?
Ovary alternates between 2 phases that lasts 28 days
64
What are the 2 phases an ovary alternates between?
1. Follicular
2. Luteal
65
What is the follicular phase?
Dominated by presence of maturing follicles
66
What is the luteal phase?
characterised by presence of corpus luteum
67
When does the follicular phase occur?
First half of the cycle
68
What does a follicle contain?
A maturing oocyte
69
What do granulosa cells in follicles secrete?
Increased amounts of estrogen
70
What is ovulation?
After follicle grows it ruptures to release the oocyte from the ovary where it enters the oviduct to be fertilised (or not)
71
When does the Luteal phase occur?
Last 14 days of ovarian cycle
72
What do old follicular cells form?
Corpus luteum
73
When does the corpus luteum become functional?
4 days after ovulation
74
What does the corpus luteum secrete?
Progesterone and estrogen
75
How long does the corpus luteum continue to increase in size for?
Another four to five days
76
What happens to corpus luteum if the released ovum isn't fertilised and implanted?
Corpus luteum degenerates about 14 days after its formation
77
During the follicular phase a rise in what signals the release of estrogen?
FSH
78
What hormone decreases as follicular phase proceeds?
FSH
-rise in estrogen inhibits FSH secretion
79
What hormone peaks mid-cycle during the follicular phase?
LH
-LH surges (positive feedback)
80
What is triggered when LH peaks mid-cycle?
ovulation
81
What happens when a mature follicle to be converted to a corpus luteum?
A decrease in estrogen output
82
What does progesterone inhibit?
Inhibits release of FSH and LH
83
What happens to the Corpus leuteum when there is low LH?
Corpus luteum degenerates
84
Once progesterone levels decline, what hormone starts to rise again?
FSH
85
The rise of FSH initiates what?
A new cycle
86
What does estrogen primarily inhibit?
FSH from anterior pituitary
87
What hormone continues to rise during follicular phase?
LH
-Estrogen alone cannot inhibit LH
88
What is an LH surge?
Positive feedback by estrogen causing a massive increase in LH secretion
89
What does an LH surge cause?
Triggers ovulation and luteinization
90
How does an LH surge cause ovulation and luteinization?
Mid-cycle it halts estrogen synthesis by follicular cells and reinitiates meiosis (meiosis I completes) and follicular cells turn into luteal cells
91
What hormone "Maintains" the corpus luteum?
LH
92
How does Lh maintain the corpus luteum?
Stimulates ongoing steroid hormone secretion by the luteal cell
93
What is the menstrual (uterine) cycle?
28 day cycle reflecting the hormonal changes during the ovarian cycle
-Menstrual bleeding once
3 phases
94
What are the 3 phases of the menstrual cycle?
1, Menstrual phase
2. Proliferative phase
3. Secretory or progestational phase
95
What is the menstrual phase characterised by?
Discharge or blood and endometrial debris from vagina
96
What does the 1st day of menstruation signify?
Start of a new cycle
97
What does menstruation coincide with from the ovarian cycle?
End of ovarian luteal phase and onset of follicular phase
98
What is released during the Menstrual phase?
Uterine prostaglandin
99
What does Uterine prostaglandin cause?
1. Vasoconstriction of endometrial vessels
2. Stimulates mild rhythmic contractions of myometrium
100
What does the vasoconstriction of endometrial vessels cause?
Disrupts blood flow
Causes death of endometrium
101
What do the mild rhythmic contractions of the myometrium do?
Help expel blood and debris from uterus out through the vagina (menstrual flow)
102
When is the proliferative phase of the menstrual cycle?
Begins with last portion of ovarian follicular phase
103
What happens during the Proliferative phase of menstrual cycle?
Endometrium starts to repair itself and proliferate under the influence of estrogen from newly growing follicles
104
When does the oestrogen-dominant proliferative phase last from?
Lasts from end of menstruation to ovulation
105
What is the secretory or pro gestational phase occur?
After ovulation when new corpus luteum is formed
106
What does progesterone do to the endometrium?
-Makes it highly vascualrized
-becomes glycogen-filled tissue secreted by glands
107
What causes a new menstrual phase to begin?
Fertilisation and implantation do not occur and corpus luteum degenerates
108
What is the site of fertilisation?
Upper third the oviduct called the ampuls
109
When must fertilisation occur?
24 hours after ovulation
110
How long can sperm survive in the female reproductive tract?
Up to 5 days
-usually survive 48 hours
111
What is triggered when the first sperms reach the ovum?
A chemical change is triggered in the ovums membrane to make it impermeable to more sperm
112
How long does it take for a sperm and egg nuclei to fuse?
An hour
113
What is a fertilised ovum called?
Zygote
114
The completion of what is triggered when the first sperm reaches the ovum?
After fusing with plasma membrane of the ovum the completion of meiosis is triggered
115
How does a fertilised ovum develop?
By dividing mitotically
116
Within weeks what happens to the fertilised ovum?
It grows and differentiates into a blastocyst which can implant
117
How does a blastocyst implant into the endometrial lining?
Enzymes released by trophoblasts
118
What do the enzymes released by trophoblasts do?
1. Digest endometrial tissue to carve a hole for implantation of the blastocyst
2. release nutrients from endometrial cells for use in developing the embryo
119
After implantation what organ begin to develop?
The placenta
120
What is the placenta?
organ of exchange between maternal and fetal blood
121
How does a placenta develop?
-Finger-like projections of chorionic tissue extend into the pools of maternal blood
-The developing embryo sends out capillaries into chorionic projections to form placental villi
122
What does the inner cell mass of a developing placenta form?
Fluid-filled amniotic cavity
-Aka amniotic sac/amnion contains amniotic fluid
123
What vein carries oxygen and nutrient blood from the placenta to the fetus?
umbilical vein
124
What arteries carry waste products and low oxygen content to the placenta?
Umbilical arteries
125
What hormones does the placenta secrete?
1. Human chorionic gonadotropin (hCG)
2. Estrogen
3. Progesterone
126
What is hCG?
Hormone that maintains the corpus luteum during pregnancy, like LH
-Placenta take over function in last two trimesters
127
What does estrogen from the corpus luteum do during pregnancy?
Maintains normal pregnancy and growth of uterine muscle mass
128
What does progesterone from the corpus luteum do during pregnancy?
Maintains normal pregnancy and inhibits uterine contractility
129
What hormone is tested for by pregnancy tests?
Human chorionic gonadotropin
during the 1st trimester
130
What secretes hCG?
trophoblast
131
What does hCG stimulate?
Steroid hormones from the corpus luteum.
132
Can pregnancy occur without hCG?
NO
No hCG = no pregnancy
133
What hormones are produced by the placenta during the 2nd and 3rd trimester?
Estrogen and progesterone because the corpus luteum begins to degenerate
134
How long is pregnancy?
From conception- 38 weeks
135
What physical change occur within a mother to meet the demands of pregnancy?
*Uterine enlargement
*Breasts enlarge and develop ability to produce milk
*Volume of blood increases 30%
*Weight gain
*Respiratory activity increases by about 20%
*Urinary output increases
*Kidneys excrete additional wastes from fetus
*Nutritional requirements increase
136
What is parturition?
Labour/delivery/birth
137
What does parturition require?
Dilation of cervical canal
Contraction of uterine myometrium to expel fetus
138
What causes the dilation of the cervical canal?
Relaxin
-Collagen fibres breakdown (estrogen andPGs)
139
What kind of cycle progresses parturition?
A positive-feedback cycle
140
What hormone is secreted when the fetus puts pressure against the cervix?
Oxytocin
141
What is the role of Oxytocin?
-Stronger contractions
-Positive-feedback cycle until delivery is complete
142
What are the stages of labour?
1. Cervical dilation
2. Delivery of baby
3. Delivery of placenta
143
What is the longest stage of labour?
cervical dilation
-Can take up to 24 hours
144
When does the delivery of thereby begin?
When cervical dilation is complete
takes 30-90 mins
145
What is the shortest stage of labour?
Delivery of placenta
146
What happens during the delivery of the placenta stage?
Second series of uterine contractions separates placenta from myometrium
147
After delivery what happens to the uterus?
Shrinks to pre gestational size (involution)
148
During gestation what promotes the development of mammary glands?
Placental estrogen and progesterone
149
During gestation what is action is inhibited on mammary glads?
Prolactin action is inhibited
150
What is Prolactin?
Stimulates milk production by alveolar epithelial cells
151
What initiates lactation?
withdrawal of placental steroids at parturition
152
What sustains lactation?
Suckling
153
What does suckling trigger?
Release of oxytocin and prolactin
154
What is oxytocin function in lactation?
Squeeze secreted milk out through ducts
155
What is prolactin function in lactation?
Stimulates secretion of more milk to replace milk ejected
