Reproduction and Development Flashcards
(137 cards)
1
Q
Fertilization:
A
A single sperm cell fuses with the plasma membrane of the ovum. The head passes into the cytoplasm and causes an electrochemical reaction in the egg. This makes the membrane impermeable to more sperm.
2
Q
Zygote:
A
A fused cell that divides many times to form an embryo, then a fetus.
3
Q
Scrotum:
A
A sac that regulates the temperature of the testes by contracting the cremaster muscle.
4
Q
Cremaster muscle when cold:
A
Contracts to bring testes close to the body to warm up.
5
Q
Cremaster muscle when warm:
A
Relaxes to bring testes away from the body.
6
Q
What is the goal of the cremaster muscle?
A
To regulate the temperature of the testes 3 degrees Celcius below normal body temperature.
7
Q
Testes:
A
Stored in the scrotum. Before birth, they develop in the abdomen and then migrate down a canal into the scrotum around the time of birth.
8
Q
Seminiferous Tubule:
A
A sperm-producing organ that appears as tightly coiled tubes. Sperm is produced yet not matured when it leaves the testes and is nourished by Sertoli cells.
9
Q
Sertoli cells:
A
Nourishes sperm in the seminiferous tubule.
10
Q
Interstitial Cells:
A
The source of the male hormone testosterone. It is scattered between the seminiferous tubules.
11
Q
What is the problem with sperm being so streamlined?
A
They only have a small amount of cytoplasm and therefore a limited energy reserve.
12
Q
The mitochondria of sperm are located between the _________ and the _______.
A
flagellum, nucleus
13
Q
Flagellum:
A
The tail-like structure that propels sperm.
14
Q
Acrosome:
A
Caps the head of a sperm cell. It is filled with enzymes that dissolve the outer coating surrounding the egg so that sperm can penetrate it.
15
Q
A human body cell contains __ chromosomes that are paired together.
A
46
16
Q
A human body cell contains __ pairs of chromosomes.
A
23
17
Q
Human body cells are called __ploids.
A
di
18
Q
A sperm or egg must only contain __ chromosomes to maintain the appropriate chromosome count.
A
23
19
Q
Haploid:
A
Half the normal number of chromosomes.
20
Q
Spermatogenesis:
A
The formation of sperm cells which occurs in the testes.
21
Q
An ejaculation contains ____ _______ sperm.
A
400 million
22
Q
Vas Deferens:
A
A tube that carries sperm from the testes to the urethra. A blockage of the vas deferens will prevent the movement of sperm from the testes to the external environment.
23
Q
Vasectomy:
A
A means of birth control.
24
Q
Ejaculatory Duct:
A
Propels sperm and semen into the urethra.
25
What are the steps sperm takes before excretion?
1. Epididymus - sperm begins to move and mature
2. Vas deferens - carries sperm from the testes to inside the body
3. Ejaculatory duct - sperm mixes with ejaculatory fluid
4. Urethra - semen leaves the penis
26
Seminal Vesicle:
Lies below and behind the bladder. Secretes thick, clear fluid into the ejaculatory duct, makes up 60% of semen's volume.
27
What is semen made up of?
Fructose and prostaglandins.
28
Prostaglandins in semen:
Chemical messengers which, once in the female, stimulate uterine peristalsis to help move semen up the uterus.
29
Fructose in semen:
Energy for the sperm.
30
Prostate Gland:
The doughnut-shaped gland which surrounds the urethra. It secretes thin milky fluid into the urethra, which makes up 20% of seminal volume. The fluid liquifies the semen, which prevents sperm from clumping together. It is alkaline, which neutralizes acid from residual urine in the urethra and the natural acidity of the vagina.
31
Cowper's/Bulbourethral Gland:
A pair of small glands along the urethra, below the prostate. It secretes viscous fluid before the emission of sperm and semen. It is thought to lubricate the penis and vagina and protect sperm from the acidity of the vagina. This is released before ejaculation but may contain some sperm which makes the pullout method ineffective.
32
Penis:
Made of three cylinders of spongy tissue. Blood fills from the arteries during arousal, and pressure seals off the veins that drain the penis. This leads to an erection.
33
An erection is parasympathetic/sympathetic.
parasympathetic
34
Ejaculation is parasympathetic/sympathetic.
sympathetic
35
Erection:
Erectile tissue (spongiosum) fills with blood which compresses veins and the urethra, which prohibits blood from leaving and urine from entering. A sphincter at the base of the bladder closes as well. Smooth muscle contraction pushes semen out of the urethra.
36
What factors lead to infertility in men?
Environmental toxins, estrogen in meat and milk, radiation, pesticides, marijuana, alcohol, and constrictive underwear.
37
What is testosterone's primary function?
To stimulate spermatogenesis.
38
What are testosterone's secondary functions?
Maturation of testes and penis, sex drive, facial/body hair, deeper voice, increased muscle strength, body oil secretion (acne).
39
In the male reproductive system, the hypothalamus releases what hormone?
Gonadotropin-Releasing Hormone (GnRH)
40
Gonadotropin-Releasing Hormone (GnRH)
From:
To:
Effect:
From: Hypothalamus
To: Pituitary
Effect: Stimulates pituitary to release LH and FSH.
41
What two hormones does the anterior pituitary release in the male reproductive system?
Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH).
42
Follicle-Stimulating Hormone (FSH) MEN
From:
To:
Effect:
From: Anterior pituitary
To: Sertoli cells in the seminiferous tubules
Effect: Stimulates spermatogenesis by the seminiferous tubules
43
Luteinizing Hormone (LH) MEN
From:
To:
Effect:
From: Anterior pituitary
To: Interstitial cells
Effect: Stimulates testosterone production by interstitial cells. It indirectly stimulates spermatogenesis because testosterone is required for sperm production.
44
What are the female external genitalia?
Two sets of labia surround the clitoris and vaginal opening.
45
Ovaries:
Lie in the abdomen below most of the digestive system enclosed in a tough protective capsule. Ovaries produce eggs (follicles) and produce female sex hormones.
46
An egg cell is called an ___.
ova
47
A cingular egg cell is called an ____.
ovum
48
What are the two female sex hormones?
Estrogen and progesterone.
49
Oogenesis:
Ovaries contain fibrous connective tissue and small groups of cells called follicles. All of the 400,000 follicles a woman will ever have are present at birth. One (very rarely 2) follicle matures and releases its egg during each menstrual cycle.
50
Of the 400,000 follicles a woman has, how many will a woman release?
Only a few hundred.
51
What are the two types of cells follicles are composed of?
Primary oocyte and granulosa cells.
52
Oocyte contains __ chromosomes and undergoes (meiosis/mitosis).
46, meoisis
53
What is a mature oocyte called?
An ovum.
54
What provides nutrients for an oocyte?
Granulosa cells.
55
What part of oogenesis occurs before birth?
Primary oogoniums develop into oocytes in the ovaries.
56
What part of oogenesis occurs every month?
Oocytes complete maturation once at a time and once a month during a woman's reproductive years. The primary oocyte grows larger and begins meiosis. This forms a secondary oocyte and the first polar body.
57
What part of oogenesis occurs once fertilized?
The secondary oocyte completes meiosis and becomes an egg and a second polar body. Ovulation occurs, and the corpus luteum secretes pregnancy hormones.
58
Ovulation:
When the outer surface of an ovary wall busts and the secondary oocyte is released.
59
Corpus luteum:
When surrounding follicle cells remaining within ovaries are transformed into corpus luteum, they secrete hormones essential for pregnancy (estrogen and progesterone).
60
If pregnancy does not occur, what happens to the corpus luteum?
It degenerates after about 10 days.
61
Fallopian tubes/Oviducts:
Conducts eggs to the uterus. Fertilization occurs here. The ovary and oviduct don't actually touch. The egg is released into the abdominal cavity and is "sucked" into the oviduct.
62
Ectopic pregnancy:
When an embryo grows in the fallopian tubes.
63
Fimbria/Cilia:
Finger-like projections and hairs that vibrate and sweep the egg into the tube by swishing body fluids toward itself. Cilia also help move the egg toward the uterus.
64
Uterus (womb):
Houses and nurtures the developing fetus. Oviducts enter at the top, and the cervix is at the bottom.
65
Endometrium:
The lining of the uterus (womb) supplied with blood vessels. It varies in thickness depending on the stage of the menstrual cycle. Hormones control it.
66
What are the two layers of the endometrium?
The basal layer and the functional layer.
67
Basal layer:
The stable layer of the endometrium that does not change thickness.
68
Functional layer:
The layer of the endometrium which changes thickness with menstruation.
69
Cervix:
The muscular band that separates the vagina from the uterus. It holds the fetus in place. Dilation of the cervix during birth permits the fetus to enter the birth canal.
70
Vagina:
The birth canal which has an average length of 7.5 cm. It has an acidic pH of 4-5, and the upper end closes at the cervix. It is made elastic to facilitate sexual intercourse and birth.
71
What female sex hormone does the hypothalamus release?
GnRH.
72
Where does GnRH go to?
The anterior pituitary.
73
FSH WOMEN
From:
To:
Effect:
From: Anterior pituitary
To: Ovaries
Effect: Release of estrogen and progesterone
74
LH WOMEN
From:
To:
Effect:
From: Anterior pituitary
To: Ovaries
Effect: Release of progesterone and estrogen
75
What hormone are female secondary sex characteristics a result from?
Estrogen.
76
What are the secondary sex characteristics of a woman?
Enlarged breasts, less facial hair, armpit and pubic hair, fat deposits in buttocks and hips, increased body fat, smaller and narrower hands and feet, a bent angle from thigh to ankle, and hyperextended elbows.
77
Flow Phase (menstruation):
Shedding of the endometrium (uterine lining) which occurs due to low hormone levels. Depicted as days 1-5.
78
Follicular Phase:
Depicted as days 6-13. A period of repair and thickening of the endometrium. FSH from the pituitary promotes follicle development in the ovaries, which causes the follicle to produce estrogen, which thickens the endometrium. FSH production decreases, and LH production increases due to GnRH.
79
Ovulation Phase:
LH causes ovulation to occur. Depicted as day 14. The secondary oocyte is released from the follicle and ovary.
80
Luteal Phase:
The final preparation of the endometrium to receive a fertilized ovum. LH stimulates the development of the corpus luteum, which causes an increase in progesterone or a degradation if the egg is not fertilized. Estrogen and progesterone inhibit GnRH, which decreases LH and FSH, initiating the flow phase again. Depicted as days 15-28.
81
What is the order of reproduction phases in a female?
Flow phase, follicular phase, ovulation phase, and luteal phase.
82
Menopause:
The end of a woman's reproductive years which occurs at the age of 45-55. Ovaries no longer respond to FSH and LH, which means they no longer produce estrogen or progesterone. Symptoms include hot flashes, dizziness, insomnia, sleepiness and depression. Hormone replacement therapy may help.
83
What are the three steps of fertilization?
1. Capacitating
2. Acrosomal Reaction
3. Fertilization
84
Capacitating:
The acidic female reproductive tract causes small pores to open in the acrosome of sperm. The membrane of sperm has receptors that detect these chemicals from the egg and allows for directional swimming.
85
Acrosomal Reaction:
Enzymes released from the acrosome digest the outer membrane surrounding an egg cell.
86
How long is an egg fertile for?
10-15 hours.
87
How long is sperm fertile for?
48 hours.
88
When must sex occur to prompt pregnancy?
48 hours before ovulation-15 hours after ovulation.
89
Clevage:
When a zygote undergoes mitosis initially without increasing in size.
90
Morula:
When a zygote goes through mitosis and exists as more than 8 cells.
91
How long does it take for a zygote to reach the uterus?
~6 days.
92
Blastocyst:
When a zygote has differentiated into its different layers. It embeds itself in the endometrium.
93
Human Chorionic Gonadotropic hormone:
A blastocyst's outer layer secretes this hormone to prevent the corpus luteum from degenerating for three months. Progesterone and estrogen will continue production, and the endometrium is maintained.
94
How do pregnancy tests work?
They detect hCG hormone in urine.
95
Chorion:
The outermost membrane of a blastocyst that secretes hCG. It intermingles with the endometrium to form the placenta.
96
Placenta:
A disk-shaped organ that contains maternal and fetal blood vessels. However, the blood doesn't mix. It allows for the diffusion of gasses, nutrients, and wastes and produces hCG, estrogen, and progesterone. Once formed, the corpus luteum dissolves.
97
Amnion:
The innermost membrane of a blastocyst next to the baby which exists as a fluid-filled sac that cushions the baby. It's filled with amniotic fluid. It protects the embryo from trauma and temperature fluctuations. It also prevents limbs from sticking to the body.
98
Allantois:
Part of the umbilical cord. Helps the embryo exchange gases and handle the liquid waste. It provides umbilical blood vessels to the placenta.
99
Umbilical Cord:
The connection between the mother and baby from the belly-button to the placenta. It carries the baby's blood to and from the placenta. It contains 2 arteries and one vein.
100
Yolk Sac:
Site of early red blood cell formation, which contributes to a primitive digestive tract.
101
Gastrulation:
When embryonic cells in the blastocyst start producing three layers.
102
Ectoderm:
The outer layer of cells which becomes skin and the nervous system.
103
Mesoderm:
The middle layer of cells which becomes the skeleton, muscles, reproductive structures, and internal organs like the heart.
104
Endoderm:
The inner layer of cells which becomes the digestive and respiratory lining and endocrine glands.
105
What weeks are the first trimester?
1-12
106
What weeks are the second trimester?
13-24
107
What weeks are the third trimester?
25-38
108
What characterizes the first trimester?
Zygote begins cell division as it moves down the oviduct and transforms into a blastocyst planted in the uterus. Development of body organs begins, and the sucking reflex is evident, major structures are present.
109
Week 4:
Heart starts beating.
110
Week 7:
Testosterone is secreted if male, which develops the testes.
111
Week 8:
The embryo is considered a fetus, and the embryo is sensitive to radiation, drugs, maternal lifestyle, and infection.
112
What characterizes the 2nd trimester?
Rapid fetus growth, active movement, and hair development, skeleton cartilage is replaced by bone.
113
What characterizes the third trimester?
Rapid fetus growth, fetal activity decreases, and it is ready for birth.
114
Parturition:
Another term for childbirth.
115
What are the three stages of childbirth?
Labour, delivery, and after birth.
116
Labour:
Involuntary rhythmic contractions of the uterus which also causes the cervix to open to a diameter of 10 cm.
117
Delivery:
Involuntary uterine contractions and voluntary abdominal contractions. The mother forces the baby out through the cervix and vagina.
118
Afterbirth:
Occurs immediately after delivery. Blood vessels in the placenta contract and separate from the uterine wall, expelled by muscle contractions.
119
What hormones induce childbirth?
Progesterone decreases, which allows uterus contractions. Oxytocin released from the posterior pituitary stimulates stronger uterine contractions. Relaxin produced by the placenta causes pelvis ligaments to loosen and creates a larger passageway for the baby. Prostaglandins also help with uterine contractions.
120
What hormones prepare breasts for lactation?
High levels of estrogen and progesterone prepare breasts for milk production.
121
A breast has about __ milk glands.
20
122
How do milk glands connect to the nipple?
Through ducts.
123
What initiates lactation?
Expulsion of the placenta causes the mother's pituitary to secrete prolactin which initiates lactation.
124
Why is the menstrual cycle suppressed in nursing mothers?
Prolactin inhibits the release of LH.
125
What hormones during pregnancy inhibit the release of prolactin?
High estrogen and progesterone levels.
126
Colostrum:
The mammary glands form the first fluid. It is thick, contains lactose and milk proteins, lacks fat, and contains antibodies.
127
When is milk produced?
A few days after childbirth.
128
What causes milk to be released from the mammary glands?
Oxytocin is released from the hypothalamus when an infant suckles.
129
What is the hormonal cycle of lactation?
1. The pituitary releases prolactin
2. Prolactin stimulates milk production
3. Suckling of the baby stimulates the pituitary
4. Pituitary releases oxytocin
5. Oxytocin causes muscle contractions that force milk into the milk ducts so the baby can nurse
130
Ultrasounds:
A non-invasive procedure that uses soundwaves to detect body structures.
131
Amniocentesis:
A long needle removes a sample of amniotic fluid from the amniotic sac surrounding the fetus. Fetal cells are cultured for 2-4 weeks, and a karyotype is produced. This can analyze for chromosomal defects and other genetic disorders.
132
Chorionic Villi Sampling (CVS):
A tissue sample is removed from the chorion, which can be performed in early pregnancies. Results are obtained in a few days but risk spontaneous abortion.
133
In Vitro Fertilization:
An ova can be surgically removed from a woman and fertilized in a petri dish. The embryo can then be inserted into a woman's uterus.
134
Vasectomy:
Effective, reversible, quick procedure and turnaround. The vas deferens are cut and sealed. Only effects the sperm content of semen.
135
Tubal Ligation:
Effective, painful and long turnaround, non-reversible. Oviducts are severed.
136
What is the birth control pill made of?
Estrogen and progesterone.
137
What does the birth control pill do?
Shuts down FSH and LH production so follicles don't develop.
