Human Reproduction Flashcards
(132 cards)
1
Q
List components of the male reproductive system:
A
- Testes
- Tubules for transporting sperm
- Accessory glands
- Penis
2
Q
What are the testes?
A
- They are the primary male sex organs.
- testes (5cm) are enclosed by sac of skin called scrotum.
3
Q
Are the testes stored at normal body temperature?
A
No, the temperature usually remains 2-3°c lower than body temp for optimal sperm production.
4
Q
What are the functions of the testes?
A
- Produce testosterone
- Produce & release sperm
- Produce nutrients for developing sperm
5
Q
What are Seminiferous tubules & how many does each testis contain?
A
- Seminiferous tubules are tightly coiled, narrow tubes within testes where sperm cells are produced.
- Each testis contains about 1000 seminiferous tubules that are lined with germinal epithelium.
6
Q
What is the Germinal Epithelium?
A
Germinal epithelium is a layer of epithelial cells responsible for producing gametes -> they give rise to sperm.
7
Q
Do germinal epithelium cells all behave the same way?
A
no, some germinal epithelium cells behave differently and produce CELLS OF SERTOLI which provide nutrients for the maturing sperm.
8
Q
What is packed between the seminiferous tubules & what do they do?
A
Leydig cells (aka interstitial cells) are packed between the seminiferous tubules & they produce testosterone.
9
Q
Explain spermatogenesis:
A
- Spermatogenesis is the process by which sperm are produced.
- In spermatogenesis, spermatids are produced and develop into mature sperm, which stay in the seminiferous tubules & epididymis until needed.
10
Q
List the tubules for transportation of semen:
A
- Epididymis
- Vas Deferens/sperm duct
- Ejaculatory duct
- Urethra
11
Q
What is the epididymis?
A
- The site where sperm are stored once matured.
- In the epididymis, sperm become motile and gain ability to fertilise.
12
Q
How long does it take for the sperm to pass through the tubules of the epididymis?
A
It takes about 20 days for the sperm to pass through the tubules of the epididymis.
13
Q
What is the Vas deferens, and what does it do?
A
The Vas deferens, aka sperm duct -> transports sperm from the epididymis to the urethra by peristaltic movements (involuntary, wave-like contractions & relaxation)
14
Q
What is the ejaculatory duct?
A
Ejaculatory duct is the duct that the ampulla (dilated end of a vessel) of the Vas Deferens leads to.
15
Q
What does the ejaculatory duct do?
A
It uses muscles in the wall of the duct to force semen along the urethra to the exterior, which results in ejaculation.
16
Q
List the accessory glands:
A
- Seminal vesicle
- Prostate gland
- Cowper’s gland
17
Q
What is the seminal vesicle, and what does it produce?
A
An accessory gland that produces yellowish, thick, alkaline fluid containing fructose sugar, vitamin C & coagulating enzymes.
- This gives sperm energy.
- Makes up 60% of semen volume.
18
Q
What is the Prostate gland, and what does it secrete?
A
An accessory gland that secretes milky, alkaline fluid containing anticoagulating enzymes & citrates for respiration to produce energy for semen.
- Activates sperm.
- Alkaline fluid neutralises the acidity of urine in the urethra and vagina.
19
Q
What is the Cowper’s gland, and what does it secrete?
A
A gland that secretes thick alkaline mucus, which allows for greater sperm mobility prior to ejaculation. (known as pre-ejaculate)
Fluid also:
- Neutralises acidity of urethra and clears urethra of urine.
- it lubricates head of penis.
- carries some sperm.
20
Q
What is the difference between sperm and semen?
A
- Semen is made in the seminal vesicle & prostate gland and is a fluid that contains sperm & other fluids from the male reproductive system.
- Sperm are microscopic male reproductive cells that fertilize an egg.
21
Q
How much does a male ejaculate?
A
A male ejaculates about 2- 5 ml of semen -> each ml containing 50-130 million sperm.
Fun fact: if a male has a vasectomy, he will still ejaculate semen, but just not containing millions of sperm.
22
Q
What is a penis?
A
A penis is the organ used to discharge semen from the male body.
23
Q
Discuss the structure of a penis?
A
- Made up of the shaft & the glans (head)
- It’s composed of 3 spongy columns of tissue.
Corpus Cavernosa (plural)
- 2 columns of this erectile tissue form upper part of penis.
Corpus Spongiosum
- 1 smaller column, which surrounds the urethra.
24
Q
What does the Corpus Spongiosum do?
A
- It forms part of the penis
- It ensures the urethra remains open during erection & ejaculation.
25
Explain an erection: (what the chicken nugget???)
- Erectile tissue fills with blood during arousal, causing an erection.
- This allows for the penis to enter vagina & release sperm near the cervix.
26
Define ejaculation:
Release of semen (containing sperm) from urethra.
27
Define orgasm:
All-encompassing term for the climax of sexual arousal.
28
What is circumcision?
The surgical removal of foreskin.
29
Why is circumcision performed?
- Performed for religious health reasons.
- As part of HIV prevention strategies in high-risk areas (shown to significantly reduce rate of infection)
30
What role do hormones play in the male reproductive system?
The pituitary gland secretes:
- FSH, which stimulates sperm development in the seminiferous tubules.
- LH, which stimulates the Leydig cells to produce testosterone.
- Both these hormones start to be released around puberty.
31
Is sperm always produced?
Yes, sperm production starts at puberty and will continue throughout life.
32
What is the structure of sperm?
- Head
- Midpiece
- Tail
------ look online at diagrams.
33
What does the female reproductive system consist of?
- Ovaries (gonads)
- fallopian tubes
- uterus
- endometrium
- Cervix
- vagina
- vulva
- Clitoris
- Labia (minora, majora)
34
What are the functions of the female reproductive system? (7)
- Makes female gametes called ova (ovum = 1)
- Receives male gametes -> sperm.
- Provides suitable environment for fertilization.
- Provides suitable environment for foetus to develop.
- gives birth to a fully formed baby.
- feeds developing foetus & baby.
- secretes hormones to keep body fit for: producing healthy ova, fertilization, healthy environment for foetus & caring for offspring.
35
Where are the ovaries developed?
The ovaries are developed inside the abdominal cavity.
36
Explain about ovaries shape and structure?
Primary female sex organs.
- Almond-shaped, about 3-5 cm long
- held in position by ligaments
- The ovaries are surrounded by a layer of germinal epithelium that divides to produce ova by a process called oogenesis (28 days)
37
What do the ovaries produce?
- ova (eggs)
- Produce important hormones like Oestrogen & progesterone.
38
Explain everything about the fallopian tubes (oviducts)
- The fallopian tubes, aka oviducts, are 10 cm long.
- They are lined with Ciliated Epithelium that helps move egg or zygote along by sweeping action of cilia and muscular contractions.
- Site of fertilization & first divisions of development.
39
Define Ciliated Epithelium:
A specialised type of epithelial tissue that has hair-like structures called cilia on its surface.
40
What is the uterus lined with?
The uterus is lined with a thick glandular layer of tissue called the endometrium.
41
How is the Uterus joined to the vagina?
Uterus is joined to the vagina by a ring of muscle called the cervix.
42
Explain the structure of the Uterus and cervix:
The uterus is a hollow, pear-shaped organ
- made up of muscular tissue
- Endometrium
- The uterus narrows into the cervix.
- The cervix is the neck of the uterus, aka the "opening" of the uterus.
43
What are the functions of the Uterus?
It homes the embryo during development.
44
Define the Endometrium:
The innermost layer of the uterus
45
How does the endometrium prepare for implantation?
It thickens and becomes more glandular.
46
Explain the structure of the vagina?
- The vagina is a muscular tube (8-9cm long) lined with a mucus membrane.
- The vagina opens to the outside. This opening is surrounded by the vulva.
47
What is the Vulva?
The Vulva is the external genitalia.
48
What protects the external opening of the vagina?
The labia -> folds of skin, protect the opening.
-labia minora
-labia majora
49
What is found in the front of the urethra?
The clitoris is found at the front of the urethra.
50
What is the clitoris?
Small mass of spongy & nervous tissue that extends deeply into the body > sexual pleasure.
51
Ovaries contain up to ____?
Ovaries contain up to 400 000 patches of cells called primary follicles.
52
What does a primary follicle contain?
Each primary follicle contains a developing ovum that is in a state of rest.
53
When does the process of making ova first begin?
The process starts long before birth.
- In the sixth month of foetal development, primary oocytes are produced.
54
What do primary oocytes eventually become?
Primary oocytes eventually become ova.
55
Explain what occurs with primary oocytes at puberty:
At puberty, there are about 400,000 primary oocytes.
- When puberty starts, about 20 primary oocytes begin to mature every month, but only ONE completes the first meiotic division approximately every 28 days.
56
The development of the ovum is called...
The development of the ovum is called oogenesis.
57
What two cycles simultaneously occur in female human reproduction & how long do they each take?
- Ovarian Cycle
- Menstrual cycle
Both these take about 28 days & interact & impact each other through hormones.
58
What is the ovarian cycle?
A recurring process with female reproductive system that prepares an egg for fertilization and reproduction.
59
List the different phases of the ovarian cycle:
1. Follicular phase -> development of the Graafian follicle (1-14 days)
2. Ovulatory phase -> release of mature ovum
(+- day 14)
3. Luteal phase -> formation of Corpus Luteum (15-28 days)
60
After puberty, what phases does the ovary cycle between & when are these phases interrupted?
- After puberty, the ovary cycles between a follicular phase and a luteal phase.
- These phases are only interrupted by pregnancy and will continue until menopause.
61
What is Menopause?
Menopause is when the reproductive capability in females ends.
62
What happens in the first phase of the Ovarian cycle?
In the first phase, the oocyte matures within a follicle.
63
What happens at the midpoint of the Ovarian cycle?
At the midpoint of the cycle, the oocyte is released from the ovary in a process called ovulation.
64
What forms after ovulation & what is its role?
After ovulation, the follicle forms a corpus luteum, which builds up and prepares hormones to prepare the uterus for pregnancy.
65
What happens with the second oocyte after ovulation?
The second oocyte passes into the oviduct (fallopian tube)
66
Where does the fertilized egg implant?
The fertilized egg implants in the endometrium (inner layer of the uterus)
67
What connects the uterus to the vagina?
The cervix (i hope you know this by now!!!)
68
What is the role of the vagina during reproduction?
The vagina receives the penis during intercourse & serves as a birth canal.
69
What is the menstrual cycle?
It's a series of monthly hormonal changes in a woman's body that prepares the uterus for a potential pregnancy.
70
Explain stage 1 of the menstrual cycle:
- Occurs from 0-5 days
- Menstruation
- Lining of the endometrium breaks away.
- A new ovum is beginning to develop in ovary for next cycle.
71
Explain stage 2 of the menstrual cycle:
- Occurs from 6-16 days
- Repair phase
- Ovum forms and matures inside the ovary
- Endometrium prepares for possible implantation
- Ovum is released on day 14 -> takes about 3 days to reach uterus.
72
Explain stage 3 of the menstrual cycle:
- Occurs from day 17-21
- Receptive phase
- Endometrium well developed & ready to receive fertilized ovum (only if fertilization has taken place)
73
Explain stage 4 of the menstrual cycle:
-Occurs from day 22-28
- Premenstrual phase
- If no fertilization occurs, functional layer of the endometrium begins to break down.
-On about day 28 this layer comes away from uterus & cycle is complete.
74
How long does the menstrual cycle last?
It can vary from 15-31 days
75
What hormones are secreted in order to begin both the menstrual and ovarian cycle?
FSH & LH
76
What marks the first day of the menstrual cycle?
The first day of blood flow, aka menstruation, marks the beginning of the cycle. (day 0)
- The uterine lining gets broken down and shed as menstrual flow.
77
What does FSH & LH do in the early stage of the menstrual cycle?
- FSH & LH stimulate the maturation of a single follicle in one of the ovaries & the secretion of Oestrogen.
78
What triggers ovulation at mid-cycle (day 14)?
Rising oestrogen levels trigger surge in LH leading to follicle maturation & ovulation.
79
What does LH do after ovulation?
LH stimulates the remaining follicle cells to form the corpus luteum, which produces both oestrogen & progesterone.
80
What does Oestrogen & progesterone do?
Oestrogen & progesterone stimulate the development of the endometrium & the preparation of the uterine inner lining for implantation.
81
What happens at the end of the menstrual cycle if pregnancy doesn't occur?
If pregnancy doesn't occur:
- FSH & LH levels drop
- This causes the corpus luteum to disintegrate and the inner lining of the uterus to shed.
- This is done through contractions within the uterus.
82
What four hormones act in coordination during the menstrual cycle?
- FSH & LH -> Gonadotrophic hormones
- Oestrogen & Progesterone -> Reproductive hormones
83
Define Fertilization:
Fertilization is when male gametes (sperm) fuse with female gametes (ovum)
84
Why is fertilization important?
- It transmits genes from both parents
- Diploid number of chromosomes
- It initiates development
85
What is used to transfer sperm into the female's body during sexual intercourse?
The penis...
86
What does movement during intercourse cause in the male's body?
Movement causes the urethra & vas Deferens to contract, moving sperm along so that they can mix with the other secretions of the accessory glands.
87
What is stimulated in the female's body during sexual intercourse & why?
- The woman's cervix is stimulated to secrete mucus.
- This lubricates the vagina.
- Neutralises acidity in vagina so sperm are not killed.
88
What can change in regards to cervical mucus during a woman's cycle?
The quantity and quality can change. (e.g: mucus is more watery when female is fertile)
89
How is sperm propelled toward the ovum during sexual intercourse?
The force of ejaculation and contractions of the wall of vagina, uterus & oviduct propel the sperm toward the ovum in the oviduct.
90
How long does the ovum survive for?
The ovum survives for about 24 hours & has to be fertilized in the upper region of the oviduct.
91
How much sperm will fertilize the ovum, and how much is released in one ejaculation?
In one ejaculation 100-300 million sperm are relased
Only one will fertilize the ovum.
92
What does the Acrosome of sperm secrete & what does it do?
Acrosome (part of sperm head) secretes lytic enzymes.
- Lytic enzymes digest the outer layer of follicle cells, so that the head of sperm penetrates the membrane.
- The tail and midpiece are discarded.
93
What does the secondary oocyte undergo?
The secondary oocyte (n) undergoes second meiotic division -> mature ovum (n) & polar body (n)
94
What is the fertilized ovum called & what do the chromosomes of it look like?
- Called a zygote
- Contains a diploid number of chromosomes.
(half from sperm & half from ovum)
95
What happens to the ovum once fertilized?
- Once fertilized, the plasma membrane of the ovum thickens so that no other sperm can enter
- The cell divides immediately by mitosis to form two new identical cells.
96
Why does the wall of the ovum thicken once fertilized?
It thickens to prevent a multinucleate zygote.
97
Define Gestation:
Gestation is a period of pregnancy which is approximately 40 weeks (9 months)
98
What parts play an important role in the development of a foetus?
- The placenta
- Umbilical Cord
- Amnion & amniotic fluid
99
What does the placenta develop from?
The placenta develops from both embryonic & maternal tissue.
100
What are the uses of the placenta?
- Allows for the exchange of materials between mother & foetus, without mixing blood.
- Allows important substances like oxygen, glucose, water, amino acids, minerals, and vitamins to diffuse from mother and foetus.
- Allows for waste like carbon dioxide & urea to diffuse from foetal blood to mother's blood
- Allows for maternal antibodies to pass into foetus
(passive immunity)
-Protects fetus by preventing most pathogens & their toxins from crossing placenta. (Some viruses, like HIV and Rubella, can still cross)
- Becomes an endocrine gland about 12 weeks after ovulation, thus taking over the function of corpus luteum to produce testosterone.
101
When does the umbilical cord develop?
It develops during the 4th week of pregnancy.
102
What does the Umbilical cord consist of?
It consists of 2 umbilical arteries and a single vein, held together by connective tissue.
103
What do arteries in the umbilical cord do?
Arteries carry waste & carbon dioxide away from foetus to placenta.
- This is so that it can be excreted into mothers blood
104
What does the vein in the umbilical cord do?
It carries oxygen and nutrients to foetus from placenta.
105
What is the amnion & when does it develop?
The amnion is a thin protective membrane that grows around and surrounds the embryo.
- It grows during the 3rd & 4th week of pregnancy.
106
What occurs after the amnion has surrounded the embryo?
the amnion encloses a cavity & secretes a fluid called amnion fluid (99% water, foetal cells & waste)
107
How are doctors able to determine whether a child has chromosomal abnormalities?
They take a sample of the amniotic fluid as it contains genetic material.
- This test is called Amniocentesis
108
What are the functions of the Amnion?
- Supports foetus -> allowing freedom of movement
- Acts as a shock absorber
- Provides a medium to practice breathing and swallowing
- Protects against temperature changes and dehydration.
109
When does birth generally occur?
Birth generally occurs 280 days from the last menstruation.
110
What happens to the hormones as the pregnancy progresses?
As pregnancy progresses, the amount of progesterone decreases & the amount of oestrogen increases.
111
What gets secreted near the completion of pregnancy?
When pregnancy nears completion, the pituitary gland secretes the hormone oxytocin.
112
What does oxytocin do?
- Oxytocin causes the uterus to contract.
- These contractions increase in strength & number during labour. (positive feedback loop)
113
What are the signs of labour?
1. Rhythmical, regular & painful muscular contractions.
2. lower back pain
3. A "show" = mucus & a little blood that passes from vagina before or after contractions start.
4. The "breaking of water" or tearing of the chorion & amnion membranes causing liquid to pour out of vagina.
114
What are 3 stages of birth?
1. Dilation of the cervix
2. Birth of baby
3. The expulsion of the "afterbirth"/placenta
115
Explain stage 1 of birth:
- The opening of Cervix begins to dilate till about 10cm in diameter -> "causes water to break"
- The uterus contracts in waves, causing baby to be pushed down, head first, into cervix.
116
Explain stage 2 of birth:
- Cervix is completely dilated
- Contractions more powerful, causing baby to be pushed out of the uterus & through the cervix & vagina to outside.
- As baby is squeezed through the vagina, the plates of the skull push together, making head smaller.
- The baby's head is usually out of shape when it is born, but returns to normal in a few days.
117
Explain stage 3 of birth:
- Once umbilical cord is clamped & cut, placenta stops functioning
- Uterine muscles contract until placenta expelled, usually between 5-30 min later.
118
Define lactation:
Lactation is the production of milk from the mammary glands.
119
What does oestrogen & progesterone stimulate the growth of during pregnancy?
During pregnancy, Oestrogen & progesterone stimulate the growth and development of the milk glands and milk ducts in the breasts.
120
What stimulates the production of milk after birth?
Prolactin stimulates the mammary glands to produce milk after birth.
121
What causes the release of milk from glands?
Oxytocin causes the release of milk from glands.
122
Why is breast milk favoured over bottle feeding?
- It contains antibodies, which can help a baby fight infections.
- Contains all nutrients needed for optimal growth.
123
What are the different birth control methods?
- Natural method
- Barrier Method
- Chemical Method
- Surgical Method
124
What is infertility?
It's the inability to achieve pregnancy.
125
What are the main causes of infertility?
-in males?
-in females?
In males:
- Low sperm count
-High % of abnormal sperm cells
In females:
- No ova produced/no ovulation
- Blocked fallopian tubes
- Hormonal imbalance
- STIs
- Stress
- Age
- Endometriosis
126
Name different treatments for infertility:
- Fertility enhances
- Artificial insemination (AI)
- Gamete-Intra-Fallopian-Transfer (GIFT)
-In Vitro Fertilization (IVF)
127
Explain fertility enhances as a treatment for infertility:
- FSH & LH are administered to stimulate ovulation
- This increases chances of natural conception.
128
Explain AI as a fertility treatment for infertility:
AI = artificial insemination
- sperm cells are injected directly into the vagina during ovulation
- Donor sperm can be used from sperm bank
129
Explain GIFT as a treatment to infertility:
GIFT = Gamete-Intra-Fallopian-Transfer
- Fertilization occurs inside body (cheaper than IVF)
- Often used in cases of male infertility.
- Woman undergoes fertility enhances, lots of ova produced & harvested.
- Sperm & ova are then placed in fallopian- tubes.
130
Explain IVF as a treatment to infertility:
IVF = In Vitro Fertilization
- Fertilization occurs outside the body in a glass petri dish in a lab.
- used if woman's fallopian tubes are blocked but the woman can still produce ova.
131
What is surrogacy?
When a woman carries & gives birth on behalf of a couple/person who is unable to have children.
132
What are the two different ways surrogacy can be done?
- IVF and implanted into a surrogate woman.
- AI if the surrogate mother provides the ova.
