Human Reproduction Flashcards
Which types of cell division occur during production of female gamete?
Meiosis
Which types of cell division occur during production of male gamete?
Meiosis
Give the precise location of the production of the female gamete
Graafian follicle
Give the precise location of fertilisation under normal circumstances
Fallopian tube [oviduct]
Name the next stage of development following the formation of the zygote
Morula
Explain the term in vitro growth
Fusion of male and female gametes outside of the body [in glass]
Suggest a reason why in IVF there is a removal of several eggs?
Maximise chances of implantation
Identify germ layer from which skin of the developing embryo arises
Ectoderm
From which tissues does the placenta form?
Endometrium [uterine] and chorionic [embyronic]
Give two reasons why the blood of the mother and baby should not mix
Blood groups of mother and baby might not be compatible
The blood pressure of the mothers system may cause damage to embryo
State three functions of the placenta
Ensures blood of mother and embryo do not mix
Produces hormones such as progesterone
Provides food to baby
State one change that occurs in the endometrium and the approximate days of the menstrual cycle on which it occurs
Day 1-5, endometrium breaks down
State one change that occurs in the ovary during the female menstrual cycle and state the approx days of the cycle on which it occurs
Ovulation
Days 13-15
Where in the body are FSH and LH produced?
Pituitary gland
State the role of FSH in female reproduction system
Stimulates follicle to develop
State the role of LH in female reproduction system
Stimulates ovulation
Name two hormones other than FSH and LH that play a role in the menstrual cycle and give their role
Oestrogen -causes endometrium to build up
Progesterone - maintains thickening of endometrium
Where does meiosis occur in the male reproductive system?
Testes
Give a function of one named gland of the male reproduction system
Cowper’s gland - secretes seminal fluid
The middle piece of the sperm contains many mitochondria. Why does a sperm fell need so many mitochondria?
Energy needed to swim long distance
The middle piece of the sperm contains many mitochondria. Mitochondria are inherited exclusively from the mother, suggest a reason why this is the case
Only head of sperm enters the egg
State the survival times of the egg and sperm in the female body
Egg > up to 2 days
Sperm > up to 7 days
In humans, widening of the female hips is one example of physical changes that distinguish the sexes but are not essential for reproduction. To what term does the definition in italics refer?
Secondary sexual characteristics
What term is used for the time in a young persons life when physical changes that distinguish sexes takes place?
Puberty
Name the hormone that maintains secondary sexual characteristics throughout the life of a male
Testosterone
Where does meiosis occur in female reproductive system?
Ovary
Where does zygote formation occur in female reproduction system?
Oviduct
Where does implantation occur in female reproductive system?
Uterus
By which type of cell division does the human zygote divide?
Mitosis
Further divisions of the zygote result in what?
A morula
What is the next development stage after the morula?
Blastocyst
Give one change experiences by the mother that indicates to her that the birth process is starting
Contractions
Water breaks - amniotic fluid
Give a short account of the birth process
Contractions of uterus pushes foetus towards cervix which causes it to dilate. Contractions also cause amnion to break, releasing amniotic fluid
The foetus passes through cervix, head first. Umbilical cord is tied and cut, leaves scar which will eventually become the belly button
The baby is born, uterus contracts again to expel after birth [umbilical cord and placenta]
Name the three germ layers in the early human embryo and for each germ layer, name a structure in the adult body that develops from it
Ectoderm - skin
Endoderm - inner lining of digestive system
Mesoderm - muscles
What is the amnion?
Membrane that surrounds embryo
Explain the importance of the amnion for the foetus
Protects embryo
What is semen?
Sperm cells and seminal fluid
Where do sperm cells produce?
Testis
Where do sperm cells mature?
Epidydimis
Where do sperm cells mix with fluid
Sperm duct
Where is semen transported?
Urethra
State two secondary sexual characteristics of the human male
Enlargement of larynx, growth of pubic, facial and body hair, widening of shoulders, increased secretion of sebum oil
Give an account of the role of oestrogen in the menstrual cycle
Oestrogen - builds up/thickens wall of endometrium, inhibits FSH and stimulates LSH production
Give an account of the role of progesterone in the menstrual cycle
Maintenance of thickening of endometrium, inhibits FSH and LH production
Name a human female menstrual disorder and give a possible cause and treatment
Fibroids
Cause - UNCERTAIN, may be due to abnormal response to oestrogen
can occur in women taking contraceptive pill
Treatment -
small fibroids - no treatment, monitor growth
large fibroids - removed by surgery or in extreme cases, hysterectomy which is the removal of the uterus
What is a morula?
It’s a solid ball of cells produced after mitosis of zygote
What is a blastocyst
Fluid filled [hollow] ball of cells produced after mitosis of morula
Which part of the system is influenced both by FSH and LH
Ovary
Give two biological advantages to breastfeeding
Colostrum and breast milk provides baby with essential antibodies
Ideal balance of nutrients for baby
Has little fat - easier to digest for baby
May help reduce the risk of breast cancer for her mother
Graph of changes in levels of two hormones and endometrium during menstrual cycle
Page 160 of exam papers
Name the hormone secreted by the corpus luteum
Progesterone
Where is sperm stored in the male reproductive system?
Epididymis
Stage two functions of testosterone
Development of secondary sexual characteristics
Sperm production
Give a cause of male infertility and suggest a corrective measure
Cause - low sperm count as a result of drugs, alcohol, stress
Corrective - changing lifestyle
What is menstruation
Shredding of endometrium in absence of fertilisation
Where is testosterone secreted in the body of the human male?
Testis
State two ways in which sperm differ from ova
Size Sperm - smaller [smallest in human] Ovum - large Shape Sperm - straight - head middle and tail Ovum - rounded
Name a gland that secreted seminal fluid
Prostate gland
Cowper’s gland
Seminal vesicles
State a function of seminal fluid
Allows sperm to swim
Provides nutrients [fructose]
What is meant by contraception?
Prevention of conception
Give an example of a surgical method of male contraception and suggest an advantage or disadvantage of the method you have named
Vasectomy - sperm ducts are cut and tied
Advantage - avoids side effects of hormonal contraception
Single procedure
Simple operation
Disadvantage - not easily reversed, no protection against STI’s
List three methods of contraception
Mechanical - use of condoms
Chemical - use of the ‘pill’ which contains oestrogen and progesterone which prevents ovulation and hence, conception
Chemical - use of spermicide
Suggest a possible effect on human population that may result from an increased availability of contraception
Decrease in population - less conception
Improved social conditions
Decrease in STI’s
What is the function of the Vas deferens (sperm duct)?
Carries sperm to urethra
What is the function of the seminal vesicle, cowpers gland and prostate gland?
Secrete seminal fluid
What is the function of the epididymis?
Stores sperm
What is the function of the scrotum?
Holds testis and keeps it cool at 35 degrees celcius
Why are the testes kept at 35 degrees celcius?
Its the optimum temperature for production of sperm
What is the function of the penis?
It introduces sperm into female reproduction system
What is the function of the urethra?
Carries urine and semen out of body
What is the function of the Testis?
Produces sperm by meiosis
Secretes testosterone
Diagram of male reproductive system
Pg 336 (answers in copy) Purple book
State the ideal temperature for sperm production?
Slightly lower than 35 degrees celcius
Name four parts of male reproductive system that help make semen
Seminal vesicle
Prostate gland
Cowpers gland
Testis
Name two liquids that pass through the urethra
Urine, Semen
What is a gohad?
It is an organ that produces sex cells
What is the female gohad?
Ovary
What is the male gohad?
Testis
What is the function of acrosome of sperm cell?
Contains digestive enzymes which digest the egg membrane
How many chromosomes are there in the nucleus of a sperm cell?
Contains 23 chromosomes
What is the function of the collar in the sperm cell?
Contains mitochondria - provides energy for sperm to swim
What is the function of the flagellum?
Allows sperm to swim
What is found in the i) head ii)middle iii)tail of a sperm cell?
i) Acrosome and nucleus
ii) Collar
iii) Flagellum
What is the term given to male hormones?
Androgens
What is the function of FSH in the male reproduction system?
stimulates sperm cells to divide by mitosis to produce sperm
What is the function of LH in the male reproduction system?
stimulates the testes to produce testosterone
What are secondary sexual characteristics?
Features that distinguish males from females apart from sex organs themselves
Are sperm and egg producing cells haploid or diploid and how do you know?
Diploid
They contain 46 chromosomes
Are sperm and egg cells haploid or diploid and how do you know?
Egg and sperm producing cells divided my meiosis to produce egg and sperm cells and have haploid number of 23 chromosomes each
What is produced when an egg and sperm cell fuse and why?
Diploid zygote - both sperm and egg nucleus are haploid with 23 chromosomes each
What is the function of the ovary?
Produces the egg and hormones oestrogen and progestrone
What is the function of fallopian tube?
Site of fertilisation
Transports egg from ovary to uterus
What is the function of the uterus?
Site of implantation
Contains endrometrium - form placenta
What is the function of the vagina?
Allows entry of sperm and exit of baby at birth
Give examples of female secondary sexual characteristics
Maturing and enlargement of breasts
Widening of pelvis to allow for birth
Growth of pubic and underarm hair
What maintains the secondary sexual characteristics in females
Oestrogen and progesterone
Give an account of the changes in the ovary during the menstrual cycle
Ovaries contains all potential eggs - diploid
After puberty, a number of eggs are produced by meiosis each month and usually only one egg grows and rest die
Divided by meiosis - Graafian follicle which produces oestrogen
When mature, follicle bursts at ovulation to release egg
After ovulation, follicle fills with yellow cells and becomes corpus luteum which secretes progesterone
What is the menstrual cycle?
The 28 day sequence of events that produces an egg and prepares the body for pregnancy
When does the menstrual cycle begin and end in a persons life?
Begins - puberty
Ends - menopause
What happens on days 1-5 in the menstrual cycle
- old endometrium sheds which is known as menstruation
- new egg is produced in ovary by meiosis and the new egg is surrounded by Graafian follicle [stim by FSH]
What happens on days 6-14 in the menstrual cycle?
-hormone oestrogen is produced by developing graafian follicle
oestrogen causes linen to build up again to prepare for implantation
stim secretion of LH and inhibits sec of FSH
What happens on day 14 of the menstrual cycle?
Ovulation occurs when Graafian follicle bursts to release egg into the Fallopian tube [stim by LH]
What happens days 14-28 in the menstrual cycle?
Graafian follicle develops into corpus luteum which secretes progesterone
Progesterone - maintains thickening of endometrium
If fertilisation does not take place, the corpus luteum starts to degenerate around day 22 which results in a reduction of progesterone levels.
As a result, the endometrium breaks down again on day 28
What is the fertile period in the menstrual cycle?
Days 12-16
How come the fertile period begins on day 12, despite the fact ovulation doesn’t occur until day 14?
Sperm can survive for a long period of time in female body, therefore on day 12 it may already be in the body
What is copulation?
Sexual intercourse
What are the stages of copulation?
Sexual arousal Sexual intercourse Orgasm Ejaculation Insemination
What does sexual arousal cause?
Penis becomes erect due to increased blood flow into spongy tissue, and can now be inserted into the vagina
Vagina is lubricated, elongated and wider in females
What is an orgasm and what occurs during an orgasm?
Climax in sexual arousal
Pelvic floor of Male and female contract and heart rates, blood pressure rises
What is ejaculation?
The propelling of semen from the penis due to sexual arousal
What causes ejaculation?
Contraction of epididymis, sperm ducts, glands and urethra in males
What is insemination?
The release of semen into the vagina at the cervix
What are chemotaxins?
If ovulation has occurred and egg is present, it releases a chemical to attract sperm
Many speak die in the female reproduction system, why?
Acidic conditions in vagina
May be attacked by WBC’s as foreign bodies
May enter the wrong Fallopian tube
What is fertilisation?
Fusion of the nuclei of male and female gametes to from a diploid zygote
How do sperm cells prevent other sperm cells entering the egg?
Sperm loses tail and the head enters egg
A chemical reaction occurs at membrane which prevents other sperm cells entering
What is implantation?
It’s the embedding of the fertilised egg into the lining of the uterus
When does implantation occur?
6-9 days after fertilisation
What is the function of amniotic fluid?
Acts as a shock absorber
What occurs after implantation?
Placenta formation
During the embryonic development, when does the heart, brain and umbilical cord form?
Week 4
When do the internal organs and limbs form during the development of the embryo?
Week 5
When do the eyes, nose, mouth and ears form during embyronic development?
Week 6
What week during the embryonic development can you tell the sex it the baby and why?
Week 8
Major body organs are formed, including ovaries and tested are visible
In what week of embyronic development, when does the embryo become a foetus?
Week 8
What is gestation?
Length of time spent in the uterus from fertilisation to birth
What is ossification and when does it occur?
Growth of bones to replace cartilage
Week 8
What hormones are produced throughout pregnancy?
Oestrogen and progesterone
What produces progesterone in the first three months of pregnancy and then for the rest of the 6 months?
three months - corpus luteum
rest - placenta
Where is oxytocin produced?
The pituitary gland
What is the function of oxytocin and when is it secreted?
Immediately before birth
Causes further contractions of uterus
What is lactation?
Secretion of milk from mammary glands
What is birth control?
Methods employed to limit the number of children that are born
What are the four different types of contraception?
Mechanical
Chemical
Surgical
Natural
How can natural contraception be employed?
Not having intercourse during fertile period of menstrual cycle
How can you identify time of ovulation?
Monitoring body temperature [rises slightly after ovulation]
Mucous secreted in the cervix [which changes its texture after ovulation]
What is infertility?
It’s the inability of a couple to achieve conception
What is one method of treating infertility between a couple, other than chemical?
IVF
How does the woman release more than one egg during IVF?
Drugs are given to the female to stimulate ovaries to produce more than one egg
Explain IVF
Mother takes drugs to stimulate ovaries to produce more than one egg
Eggs of mother are taken from female body into the lab
Sperm sample is taken from male
Egg and sperm are mixed together in hope that fertilisation will occur
once it forms a [zygote - morula] blastocyst and eventually an embryo, it’s placed back into the females body for implantation
What are fibroids?
They are benign tumours of the uterus as a result of the over production of cells
What are the symptoms of fibroids?
Produce heavy and prolonged menstrual bleeding [lead to anemia, pain, miscarriage or infertility]
