Hey guys, welcome back to another Biology with Zhan Xuan video, so today, we will hop into chapter 15. Probably one of the largest Topics in the
biology syllabus, and this is probably the second most students usually will understand a
bit much better which is definitely reproduction in humans, so as we are hopping into the second
part of the reproduction chapter video this time, we are going to cover humans, which is stated from
the new syllabus 15.5 to 15.11 all right so disclaimer about this video as it must be
watched by viewers who are required to be much mature and whatever is being viewed later
on and please use this information for the use of your educational purposes and not for
any gory detail. So enjoy the video of course so section one sexual reproduction. So as we know there are two different of reproduction which is one is asexual and one is sexual reproduction
so you have to watch back for what is asexual reproduction about plants and but today we're
just going to focus about sexual reproduction so sexual reproduction is the full definition of
it means the process of involving the fusion of the nuclei of two gametes or what we call it
as sex cells to form a zygote and the production of offspring that are genetically different from
each other so humans like your brothers and your siblings they are both genetically look different
so a zygote means fertilized egg cells and Fertilization means a fusion of gamete nuclei
it looked more into that later on. So there are two different things when it's called a gamete and the zygote where it's being classified as haploid and diploid so the nuclei
of gamete is called haploid, so it contains half of the number of chromosomes. Remember that one human cell requires forty-six chromosomes where each 23, 23 and nucleus of a zygote is
called a diploid where it contains the full sets of chromosomes so then the claim meaning is the the central core of the nucleus of the atom or okay okay so this is how it looks like so it requires
a sperm and an ovum to be fertilized together to form a diploid zygote so before that they are
both called haploid because all of them only have half of the set of chromosomes therefore
it forms a diploid. What inside contents it contains is the maternal homologue and the paternal homologue means it's male and female technically okay so the advantages and disadvantages between wild species and Crop Production so if advantages would be genetic variation there's reduced
risk of Extinction and secondly is a crop production, it has variety in yield and this
advantages would be very time-consuming and there are a lot of resources required to make it
happen and a mate means you need to have someone in order for you can have this sexual reproduction going on and for a disadvantage we have a lower yield, less economic gains, Offspring phenotypes characteristics and it cannot be controlled okay okay we're going to enter this section to the
introduction to the unisex reproduction system between male and female okay so the first one
would be the female human reproductive system so pretty sure you guys have seen this before
so you can see there's the fallopian tube and those left and right of the reproductive system
that's an ovary and once the between there the the middle is the womb lining with the womb or it can be called as the uterus and there will be the neck of the womb or we call it a cervix
and in the end, is the vagina all right. So the features of it the functions the ovary is
to produce more ovum and oviduct is where the fertilization occurs the uterus lining
is where the implantation of the zygote begins and the cervixes allow the flow of
menstrual blood to the vagina you're going to learn this more in the menstrual cycle
later on in this video and the vagina is when it receives the penis using sexual
reproduction. Oh sorry sexual intercourse okay, so this is how the cross-section looks like
of a female reproductive system, so the same thing both of them are the fallopian tube and we can see that's the uterus middle and oviduct and ovaries Oviduct will produce the egg cells the uterus
is where the embryo develops and the cervix is the ring of muscle and vagina is when it receives
the sperm from the penis doing sexual intercourse and the cross-section, you can see that's the
rectum and the anus below there, so most of you can see there are some similarities between the left side and the right side of the cross-section okay all right the next one is the male reproductive
system okay this is we also have seen this before so definitely in one of the things you can see is
that there's a ureter on the top and there's the a seminal vesicle, the prostate glands, the epidermis the testes, the urinary bladder the erectile tissue urethra and, of course the glands penis
okay so the features of everything of this is the testis is the one that produces the sperm
just now what it produces the ovaries are the oviduct and scrotum is where it maintains the
temperature of the test is slightly lower than body temperature again what it all links to this
is homeostasis and prostate glands are the secret that alkaline fluid to protect the sperm and the
the urethra is to carry semen and fluid during erection and penis is where it carries the sperm to the
cervix epidermis is when it stores the sperm and the sperm duct is when it transports the Semen from the testis to the urethra okay so again this is the cross section of how it looks like so of
course we know that's a seminal vesicle at the top but those which are not highlighted you don't
have to know this you just have to know what is being highlighted and the prostate glands as well as secretes the sperm so sperm plus fluid equals to semen and the sperm duct is where it connects to testes to the urethra and it is where the urine and sperm leaves the body so same thing that
is what is being held in here the testis and the which produces sperm and the cross-section of it there's a bone the rectum in the anus same as the female reproductive system cross-section
also okay so what's this different it's just it's all different words again okay and the
difference between the male gamete versus the female gamete which is the sperm and the
ovum of course which the meal damage is much smaller and the structure of it is much elongated
and streamlined for swimming when it's being done after sexual intercourse and the mobility is for
the flagellum to swim and the numbers are millions each contains 23 chromosomes half the set of it
and the female gamete is much larger therefore it's much spherical contains a lot of protein and
fat in the cytoplasm and it doesn't move in itself but it's moved by the Cillia what is it linked to
the ciliated cells in the Oviduct and it's one Per month and again half set of the chromosomes 23 okay so the ovum same thing but now there's an additional kind this is the cell of it right now
so this is the layer of jelly that you call that or it's kind of the protection of the ovum and the
cell surface membrane. Yes it's the same exactly the speeches of the normal cell and the cytoplasm contains lots of protein, and fat contains the yolk and nucleus containing chromosomes. This one of course, the diameter of it is about 0.1 millimetre the sperm remember there's a flagellum which
is adapted for swimming and the length of it is about point or 0.05 millimetre that's the head and it contains the nucleus containing chromosomes and the mitochondria to release energy to swim and
the acrosome is for the vesicle containing enzymes to dissolve away through the jelly surrounding
the egg cells all right so we'll move on to the fertilization right now so of course male
and female they are produced they are oven and male produced a sperm and once they do sexual
intercourse they will happen to become a zygote remember it's called a fertilized egg cell it
means that are for this chromosomes in together in total there are 23 Pairs and once after
fertilization it has become an embryo same thing for this chromosomes in 23 paths okay so
fertilization this is how it happens so if there is an egg in the OV duck it will be fertilized
immediately once the sperm has entered the um the uterus wall and the sperm to swim through
the uterus and to the ovary lock to find the ovum and the sperms are left in the top of the
vagina okay once it's being once most of it has been traveled up ready and the Egg membrane stops
more sperm from getting through it only penetrates one means all of the millions of sperm that got
passed through only one can go into the egg and the nucleus of the successfully perfuses with the
egg nucleus therefore it starts to fertilize okay so this is now we are entering into implantation
so firstly is where ovulation starts a mature follicle bursts and releases an egg into the
oviduct therefore it starts to fertilize with a sperm entering to form a zygote therefore the
zygote divides and after several hours a ball of cells are formed because they have to do mitosis
and the cells in the ball keep dividing as it expands and if that while it moves down to the
oviduct now at that stage it's called an embryo next number six is where implantation Begins the
embryo sinks into the soft lining of the uterus and a placenta has formed you will need to know
the meaning later so this is again kind of how it looks like again okay and yeah yeah so the
definition of implantation is the attachment of the fertilized egg to the uterine lining all right
so you can see from there ovum travels towards the uterus but a rhythmic movement using chord
peristalsis movement then we learned this from transport and animals where most our esophagus
are going in and peristalsis movement and once the ovum is fertilized it becomes impenetrable
means others other sperms that were left out were there to die and the zygote you see via mitosis
and implants to form into the uterus into the uterus lining so that will the implantation
starts from that attachment of the fertilized egg to the uterine lining okay so after all of
the implantation of this being fertilized it has started to grow okay so that's where we can see
that the um the embryo has already expand and of course it's not really a baby yet it's called
an embryo for a reason it's protected by what you call a fluid called the amniotic fluid and
it's covered with the amniotic membrane again it's filled with the amniotic fluid to protect
the embryo so we have a lot of things connected together what we call it as the umbilical cord
which helps to transfer oxygen and removes carbon dioxide okay so everything all starts from the end
all the food we'll be all going into the embryo so you can see it from the top deoxygen blood from
the mother it carries the waste products from the embryo starting and oxygen blood from mother
carries food and oxygen to the embryo so you see the baby the embryo requires food and oxygen
in order they can grow and survive longer okay so yeah inside is the end ion the placenta the
amniotic fluid and the embryos inside there okay so yes from the same thing just now we can see
the lining of the uterus the vein from the mother so of course oxygen blood and food must always
go to the embryo and the fetus blood is separated from the mother's blood but a thin wall of
placenta so the blood cannot mix together and it's an umbilical cord same thing as always
continuing and R3 and a vein must remember how the artery and vein works okay so this is the
end ion simply there's always a muscular wall the spongy line of the uterus and there's a clock of
mucus in the cervix another fluid that an iron on the vagina is just that so after it's been grown
then it starts to squeeze in the cervix and enters out of the vagina so continue we can see there's
the placenta the umbilical cord everything the same thing now the cross section of how it looks
and that time is where the wall of the cervix has become gradually wide enough for the baby's head
to pass out from the vagina so the wall vagina is stretch allows the baby to be pushed through push
push out loud basically okay so again same thing but this is much deeper right now so the niotic
sac is to protect the baby plus it makes um 90 foot just to protect the surrounding as called
what you call a shock absorber and the cycle of exchange of diffusion remember the capillaries
of the arteries and veins the fetus receive the Oxygen Plus dissolved nutrients and the fetus
removes O2 and urea so again what they mostly do here is diffusion and the placenta X is the
barrier from toxins and pathogens some toxics can pass across the placenta and affects the feta such
as nicotine nicotine come from smoking that's why pregnant mothers cannot smoke otherwise it will
affect the baby so Adam Court connectors from the belly button is when it's attaches to feeders
to the placenta to plus contain blood vessels to transport blood okay so function of the placenta
surely is to provide oxygen nutrients removes urea or any other waste products and is connected
to the uterus lining the function of the umbilical cord is a supplies nutrient-rich blood to
the fetus and exit of wasted products and it connects placenta to the fetus and the
function of the amniotic sac is houses the fetus with the analytics fluid it's a protection
and to regulate the temperature inside them stomach the next one is antenatal care okay
so periodically you have to go for checkups and you must consume essential nutrients okay
such as those as we know and exercise a lot and of course it's a healthy balanced diet and plus
it will impact the nutrients maybe even vitamin supplements okay then buff labor and childbirth
so again it's firstly they break the amniotic sac first and it can you do uterus starts to
contracts the dilation occurs in the cervix and the passage of the body comes through the vagina
first thing hit comes out first and legs are the last and tying and cutting of the umbilical
cord forms in the belly button okay see and delivery of after above the placenta so yeah you
can see it's nearly the same here all right okay section four will be puberty and sex hormones in
humans so puberty starts from around 10 and ends at 18. so changes in male is of course the pen the
penis and the taste testis are enlarged the sperm starts to be produced the secretion released from
the prostate glands starts to occur and secondary sexual characteristics is growth or chest pubic
and armpit hair the voice deepens because of the changes in the Rings you should know where the
larynx is from respiratory system and changes in female will be ovulation occurs menstruation
starts uterus and the vagina grow bigger then secondary sexual characteristic will be the breast
being developed the growth of the pubic and armpit hair body changes the hips widen and the waist
narrow due to the vagina okay of course and men's jewelry cycle one of the most important
things that you have to know so discharge of blood uterus lining and ovum ovary follicle
follicle releases over and Compass lithium so again this is just another kind of like cycle
so ovulation the follicle will be releasing an egg cell from the ovary fertilization could
take place but the follicle turns into a curved lithium and the line of the uterus becomes
more vascular receive the embryo from if the egg is fertilized and menstruation as the
egg has not been fertilized to take uterus lining is not needed and it starts to break down
gradually loss through the vagina and after that inside the ovary a follicle containing an
Excel develops the uterus lining is again repaired all right so yeah okay here we can see
is the follicular phase and the luteal phase so menstruation occurs for 28 days and see you can
see that the estrogen increases and until the LH um is the peak and then it goes down as the day
increases and the push progesterone increases again so the hormone of FSH is produced by the
pituitary glands where it causes the egg to grow mature into follicles and it stimulates the
ovaries to release estrogen see estrogen takes over so the estrogen is produced by the ovary
or the follicle causes the lining of the uterus to develop and thicken okay and cause the LH to
be released and inhibits FSH see okay and LH is produced by the pituitary glands causes ovulation
to occur and eight releases from the follicle or the ovary and lastly Pro it progesterone increases
again from the Corpus lithium or the placenta when it's pregnant then the maintain the lining of the
uterus so fertilized it can implant and inhibits the LH and so no more aches are being released so
no ovulation occurs again all right so okay see I've already stated already so FSH is basically
means the follicle stimulating hormone and LH is the luteinizing hormone same thing why I say
that's not you can have a look again and care what it can occurs is the alternator can infant
care or breastfeeding versus spot to feeding all right okay so the advantages between
breastfeeding versus bottle feeding is that breastfeeding balance of nutrients it's free
temperature antibodies are being passed on together and bottle feeding is that you're able to
monitor the amount being consumed anyone can feed and disadvantages is that infant determines
the amount consumed only mothers can feed the medication and or diets affects breast
milk together and bottle feeding is harder to digest and needs warming therefore the milk
powder the milk content is expensive all right okay lastly of this is Section 5 methods
of birth control so of course you can see a textbook of page 180 to 181 firstly it's
natural adaptation or requires natural birth control or artificial adaptation chemical
method mechanical method or surgical method so the chemical method is where you insert
an IUD on inter intra untering device or to prevent fertilization and implantation to occurs
and the intractory system or in IUS this is what you just have to know for chemical birth control
and some people they use contraceptive pills okay implant or an injection another thing is
this all right so next one is mechanical method so mechanical method one of it is the
condoms next one is the femidom the third one is the diaphragm area of method of birth
control and it blocks the sperm from entering the vagina okay before that there are details
that you should know so first thing for variable control is the condoms are being placed over
an erect penis and it collects sperm plus semen together and the femidum is placed inside the
vagina collects a sperm and semen so sperm cannot reach the egg and the diaphragm is kept and is
placed over the cervix the reason is this to stop the passage of sperm to uterus all right okay next
one surgical birth control or the surgical method one of it is called a vasectomy and the one is
female sterilization where therefore sperm Ducks cut and the cut ends tight and the one is the
surgical cut cutting of the oviducts so for the vasectomy is to not allow any more sperm being
ejaculated and female sterilization is to stop the eggs reaching the uterus okay so both of them
have different kind of methods in male and female okay remember guys uh for methods of birth control
in human it doesn't happen anymore in the 2023 syllabus so therefore you don't really have to
know this but it's good for again to read a bit so you can know how to do some questions okay so
fertility treatment is FSH in vitro artificial insemination from a donor or a surrogate mother
so yes this is another type of fertility treatment that can occur all right okay next one in vitro
fertilization IVF so where the LH and the FSH is being injected to release several eggs and the
eggs are fertilized with sperm in the laboratory and embryo returned to a woman's uterus okay
then artificial insemination is how it looks like it is and that's all boom sex section six
last section of the video sexually transmitted infection or we call this STIs famously okay
first thing sexual transmittal infections are basically infection that is transmitted via
body fluids through sexual contract contact basically so one of it is the HIV or because
the human immunodeficiency virus infection and also the quiet immune deficiency syndromes or we
call it aids okay so HIV infects the lymphocytes destroying lymphocytes and the immune system is
compromised to be unable to fight pathogens means any of the contraction of covid-19 exam people
you the lymphocytes cannot do anything okay so that's all so HIV can definitely occur in any way
sharing needles of course unprotected sex mother to fetus blood transfusion and the control
spread of STIs is avoid from unprotected sex and virus equals attacks and kill and doesn't
allow it to default from defend to any regular illnesses and if you got AIDS slightly you can
die from the infection that is not normally life-threatening all right so that's all for
this this is the final part of chapter 15 of reproduction okay hope to see you guys in the
next video try to understand it better okay you need time to really digest this information
all right see you in the next video bye bye