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bio chap 12 reproduction in humans Flashcards

1
Q

name the female and male gamete and how many chromosome each gamete contains

A

female: egg/ ovum
male: sperm

23 chromosomes

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2
Q

what is sexual reproduction

A

a process involving the fusion of nuclei of the male and female gametes to form a zygote and the production of genetically dissimilar offspring

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3
Q

what is the role of sexual reproduction

A

ensures the normal number of chromosomes is restored in the zygote

any change in chromosome number may result in the baby being born with birth defects

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4
Q

why are genetically dissimilar offsprings produced by sexual reproduction

A

male and female gametes come from 2 different parents

the nuclei of male and female gametes carry different combinations of genetics from the parents

upon fertilisation, genes combine to form an individual with a unique combination

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5
Q

what are female and male gametes formed

A

testis

ovary

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6
Q

what is the info and function of the testis

A

2 testes

each testis produces sperm and male sex hormones responsible for development and maintenance of the secondary sexual characteristics in males

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7
Q

what is the info and function of the scrotum

A

both testes lie in a pouch like sac
outside the main body cavity with a lower temp than body temp

regulate temp of testes essential for sperm to develop properly

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8
Q

what is the info and function of sperm duct

A

loops over a ureter and opens into urethra

after sperm are released from a testis they travel through sperm duct

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9
Q

what are the info and function of the prostrate gland and its secretions

A

at the base of the urinary bladder where 2 sperm ducts join the urethra

secretes a fluid - semen mixes w sperm

contains nutrients and enzymes which nourish sperm and stimulates them to swim actively

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10
Q

what are the info and functions of the penis

A

erectile organ

enters vagina during sexual intercourse to deposite semen containing sperm

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11
Q

what is a sperm

A

male gamete

numerous sperm produced throughout the life of a male human after he has become physically mature

sperm is about 60 micro meters long

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12
Q

what is the info and function of sperm head

A

about 2.5 micrometers wide
large nucleus with small amount of cytoplasm

nucleus carries one set of chromosomes of male parent

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13
Q

what is the adaptation of middle piece of sperm

A

middle piece contains mitochondria which provides energy for the sperm to swim towards the egg

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14
Q

what is the function of tail/flagellum

A

the beating movement of tail enables sperm to swim towards the egg

tail allows the sperm to be motile

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15
Q

what is the journey of sperm

A

testis -> sperm -> urethra -> outside the body

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16
Q

what is the function of the urethra

A

two ovaries produce ova
each ovary produces hormones such as oestrogen and progrestrone
female sex hormones are responsible for development and maintenance if female secondary sexual characteristics
when the eggs become mature they are released from ovary

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17
Q

what is the function of the oviduct

A

each ovary releases mature eggs into an oviduct
egg usually fertilised in oviduct

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18
Q

what is the adaptation of the oviduct

A

each oviduct is a narrow muscular tube leading from ovary to uterus

has a funnel-like opening lying close to the ovary making it easier for egg to enter oviduct

inner surface lined with cilia helps to move egg along oviduct

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19
Q

what is the function of the uterus

A

where the fetus develops during pregnancy

has smooth inner lining (uterine lining) where embryo is implanted

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20
Q

what are the adaptations of uterus

A

has elastic muscular walls

the smooth muscle tissue in walls of uterus contract pushing fetus out during birth

21
Q

what are the info and function of cervix

A

ring of muscles at the larger portion if uterus where it joins the vagina

opening of cervix allows menstrual blood to flow out into the vagina during menstruation

22
Q

info ab vagina

A

vagina/birth canal leads from the cervix to the outsude m

semen in deposited in the vagina during sexual intercourse

23
Q

info ab the ovum

A

females born with all potential eggs they will ever have
-> 70 000 potential egg cells present in the ovaries at birth
-> only 500 will become mature
-> about 1 mature egg released per month from puberty to menopause age

spherical ~120mcm - 150mcm wide

24
Q

what are the adaptations of the ovum

A

has abundant cytoplasm

surrounded by a cell membrane which in turn is surrounded by an outer membrane which chanhes during fertilisation

preventing other sperm from entering the egg

25
what is menstruation
the monthly discharge of blood or menses from the uterus via the vagina
26
what is the usual menstrual cycle length
21-33 days
27
factors affecting length of menstrual cycle
stress illness unbalanced diet tiredness malnutrition
28
what is menopause
as a female ages the ovaries will stop releasing eggs and the menstrual cycle with stop takes place between 45-55 y/o
29
what happens during menstruation
uterine lining and unfertilised egg break down and are shed with the same blood
30
what happens after menstruation / function of oestrogen
ovary produces oestrogen hormone causes uterine lining to repair and thicken high oestrogen concentration leads to ovulation
31
what happens during ovulation
on the 14th day an ovary releases an egg into the oviduct 2 ovaries take turns to release an egg
32
what happens after ovulation / function of progestrone
ovary produces a hormone - progestrone functions - prevents ovulation and further development of eggs & causes uterine lining to thicken further preparing it for implantation and growth of the embryo oestrogen production decreases if no fertilisation occurs progestrone production decreases uterine lining breaks down and whole cycle repeats
33
how is the thickness of the uterine lining affected
affected by changes in conc of hormones
34
what are the fertile and infertile periods of the menstrual cycle
egg can survive in oviduct for up to 24h if ovulation occurs on the 14th day the egg can survive from day 14 to 15 sperm can survive in the female reproductive system for 3-5 days hence sperm deposited into the vagina on day 10 can fertilise the egg and bring about pregnancy hence fertilisation is possible if sexual intercourse occurs during day 10-15 of the menstrual cycle or the fertile period rest of the days are hence the infertile period
35
what happens when no fertilisation occurs
egg breaks down blood progrestrone level decreases on 28th day without progestrone, uterine lining begins breaking down and menstruation begins again
36
what happens if fertilisation occurs
fertilised egg becomes a zygote and develops into an embryo ovary secretes progrestrone and oestrogen causing maintenance and thickening of uterine lining for the implantation of the embryo embryo embeds itself in uterine lining until placenta formed ovary continues to secrete progrestrone and oestrogen until placenta able to take over production of hormones
37
how does the penis enter the vagina
when a male becomes sexually aroused blood is pumped into the penis faster than it can return to the bloodstream via veins blood fills spaces in spongy tissues of penis becoming stiff and erect allowing it to enter vagina of female
38
what happens after the male has ejaculated
sperm in semen able to swim up oviducts of the female chemical in semen make sperm tails beat propelling sperm along oviducts sperm meets egg in oviduct causing fertilisation to occur millions of sperm released into the vagina after ejaculated however only one fertilises the egg
39
what is fertilisation
process by which the nucleus of the male gamete fuses with the nucleus of the female gamete to produce a zygote
40
how does fertilisation occur
only one nucleus enters the egg sperm nucleus fuses with egg nucleus causing a zygote to form as soon as the sperm has entered the egg, no other sperm can enter and the remaining eventually die
41
how does the embryo develop
1. cilia lining in inner surface of oviduct sweep the zygote along the oviduct movements in wall of oviduct also help move the zygote to uterus 2. zygote divides to form a ball of cells, an embryo energy needed for this early stage of cell division is provided by nutrients stored in egg takes about 5 days for embryo to reach nucleus embryo may float freely in uterus for about 2 days 3. implantation: embryo is embedded in uterine lining occurs about 7 days after fertilisation 4. embryo continues to develop in humans, 10-12 weeks aft fertilisation, all major organs develop embryo is now known as fetus after 9 months of pregnancy, fetus fully formed and ready to be born
42
what is an STI
a disease spread or transmitted through sexual intercourse can result in irreversible physical damage and death
43
what are the causes of STIs
caused by bacteria or viruses carried in the bloodstream of the infected person transmitted to an uninfected person - through semen when it comes into contact w mucous membrane of vagina - through fluid in the vagina when it comes into contact with mucous membrane in vagina - when blood from an infected person gets into bloodstream of uninfected person
44
what is the effect of HIV
destroys body's immune system that protects a person against infection may develop into AIDS - acquired immune defiency syndrome
45
how does HIV destroy the body's immune system
normally when foreign particles enter bloodstream, lymphocytes can detect them and WBCs stimulated to produce antibodies destroying bacteria and viruses however HIV destroys WBCs causes body to be unable to produce enough antibodies to protect person against many other diseases hence infections which are normally mild may be fatal to those with AIDS/ HIV
46
what are the signs and symptoms of AIDS
pneumonia brain infection chronic fever widespread tubercolosis affecting many organs at the same time severe diarrhoea lasting months Kaposi's sarcoma / cancer of blood
47
what are the 4 ways HIV is transmitted
sexual intercourse with an infected person sharing hypodermic needles with an infected person - drug addicts sharing needles - needles used for tattooing, acupuncture or ear piercing may not be sterilised properly through blood transfusion w an infected person through pregnancy -> infected mother to fetus
48
what are the 3 ways to prevent and control HIV transmission
keep to one sexual partner or abstain from having sexual intercourse males should wear a condom do not share instruments likely to break skin / contaminated with blood - go to reliable operators if you require acupuncture treatment, ear piercing or tattooing - ensure needles used are sterilised or insist on using disposable instruments removes living microorganisms such as bacteria and viruses from instruments

bio (11 decks)

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