Chapter 17: Reproduction in Humans Flashcards
(44 cards)
1
Q
Parts of male reproductive system
A
- Testis
- Scrotum
- Sperm duct
- Prostrate gland
- Urethra
- Penis
2
Q
Testis
A
- there are 2 testes
- each produces sperm
- each produces male sex hormones such as testosterone
- male hormones responsible for development and maintenance of the secondary sexual characteristics of males
3
Q
Scrotum
A
- testes lies between thighs
- both testes lie in a pouch-like sac called the scrotum
- outside the main body cavity 👉 it is at a slightly lower temp than body temp, which is essential for sperm to develop properly
4
Q
Sperm duct
A
- each sperm duct loops over a ureter and then opens into the urethra
- after the sperm are released from the testis, they travel through the sperm duct
5
Q
Prostate gland
A
- at the base of the urinary bladder, where the 2 sperm ducts join the urethra
- secretes a fluid which mixes with the sperm
- the fluid contains nutrients and enzymes which nourishes the sperm and stimulate it to swim actively
- the mixture of fluid and sperm is the semen
6
Q
Urethra
A
- a tube that passes from the bladder through the centre of the penis to the outside of the body
- both semen and urine pass out of the body through the urethra
7
Q
Penis
A
- an erectile organ
- enters the vagina of the woman during sexual intercourse to deposit semen
8
Q
Structure of sperm
A
- Sperm
- Head
- Middle piece
- Tail (flagellum)
9
Q
Sperm
A
- the male gamete
- numerous sperm are produced throughout the life of a male after he has physically matured
- about 60µm long
10
Q
Head
A
- about 2.5µm wide
- contains a large nucleus with a small amount of cytoplasm
- nucleus carries a haploid set of chromosomes
11
Q
Middle piece
A
- contains numerous mitocondria
- mitochondria provides energy for the sperm to swim towards the egg
12
Q
Tail (Flagellum)
A
- the beating movement of the tail or flagellum enables the sperm to swim towards the egg
- the tail the sperm to be motile (able to move)
13
Q
Female Reproductive System
A
- Ovary
- Oviduct
- Uterus
- Cervix
- Vagina
14
Q
Ovary
A
- 2 ovaries produces ova(eggs)
- also produces hormones such as oestrogen & progestrone
- female sex hormones are responsible for development and maintenance of the secondary sexual characteristics of females
- when the egg become mature, they are released from the ovaries
15
Q
Oviduct
A
- each ovary releases mature eggs into an oviduct
- each oviduct is a narrow, muscular tube leading from the ovary to the uterus
- has a funnel-like opening lying close to the ovary which makes it easier for the egg to enter the oviduct
- egg is usually fertilised in the oviduct
- inner surface of the oviduct is lined with cilia
- movement of cilia helps to move the egg along the oviduct
16
Q
Uterus
A
- where the fetus develops during pregnancy
- shaoed like an upside down pear
- has elastic muscular walls. the smooth muscle tissue in the walls of the uterus contract to push the fetus out during birth
- the soft, smooth inner lining of the uterus is called the uterine lining, which is where the embryo is implanted
17
Q
Cervix
A
- ring of muscles at the lower portion of the uterus where it joins the vagina
- the opening of the cervix allows menstrual blood to flow out of the vagina during menstruation
18
Q
Vagina
A
- leads from the cervix to the outside
- semen is deposited in the vagina during mating or sexual intercourse
19
Q
Ovum
A
- the female gamete
- @birth, about 70 000 potential egg cells are already present in the ovaries, but only 500 will become mature within the 2 ovaries
- usually only 1 mature egg is released every month from when they become physically mature till 45/55 years of age
- about 120µm to 150µm wide
- has abundant cytoplasm which may contain a small amount of yolk
- surrounded by a cell membrane which in turn is surrounded by an outer membrane which changes during fertilisation to prevent other sperm from entering the egg
20
Q
Diff between male and female gametes
A
Male sperm:
- has a head, middle piece and tail
- contains either X or Y chromosomes
- about 60µm long with a diameter of 2.5µm (head)
- has a tail that enables it to swim towards oviduct
- large no of sperm is released per ejaculation
————————————
Female gamete:
- spherical in shape
- has 1 X chromosome
- diameter of 120µm to 150 µm
- passive movement of egg along oviduct due to movement of cilia and peristalsis of oviduct wall
- only 1 egg released per month
21
Q
Stages in menstrual cycle
A
- Menstruation
- After menstruation
- Ovulation
- After Ovulation
22
Q
Menstruation
A
- Day 1 to 5
- uterine lining and unfertilised egg break down and are shed with some blood
23
Q
After menstruation
A
- Day 6 to day 13
- ovary produces oestrogen
- oestrogen causes uterine lining to repair and thicken
- high oestrogen concentration leads to ovulation
24
Q
Ovulation
A
- Day 14 to 15
- on the 14th day, one ovary will release an egg into the oviduct
- the 2 ovaries will take turns to release an egg
25
After ovulation
- Day 15 to 28
- ovary produced progesterone
- progesterone prevents ovulation and further development of eggs
- progesterone causes uterine lining to thicken further, preparing it for implantation and growth of embryo
- oestrogen production decreases
- if not fertilisation occurs, progesterone production decreases
- the uterine lining breaks down and while cycle repeats
26
Functions of oestrogen
- repairs and thicken uterine lining
27
Functions of progesterone
- prevents further ovulation and further development of eggs
- causes uterine lining to thicken further, preparing it for implantation and growth of embryo
28
Hormone levels changes
Progesterone:
- lowest from day 1 to 13
- increase from day 14 until 20smth
- decrease from day 20smth to 21
————————————
Oestrogen:
- lowest on day 1
- increases from day 1 to around 12
- decreases from day 12 to 20
- a little bump from day 20 to 28
29
What happens if no fertilisation occurs?
- egg breaks down
- blood progesterone level decrease
- on 28th day, w/o progesterone, uterine lining begins to break down.
- Menstruation begins again
30
What happens if fertilisation occurs
- egg becomes a zygote, which develops into an embryo
- ovary secretes progesterone and oestrogen
- causes the maintenance and thickening of the uterine lining for the implantation of the embryo
- embryo embeds itself in the uterine lining lining until a structure called the placenta is formed
- the ovary continues to secrete progesterone and oestrogen until the placenta is able to take over the production of the 2 hormones
31
Fertile and infertile periods in the menstrual cycle
- egg can survive for 24 hours
- sperm can survive 3 to 5 days
- day 10 to 15 is hence the fertile period
- rest of the days are infertile period
- this is only true assuming that the woman's period is regular and 28 days
32
Fertilisation
- the process by which the nucleus of the male gamete fuses with the nucleus of the female gamete to produce a zygote
33
Process of fertilisation
1. Only 1 sperm nucleus enters the egg. The sperm nucleus fuses with the egg nucleus to form a zygote
2. as soon as the sperm has entered the egg, no other sperm can enter. The remaining sperm which did not fertilise w/ the egg will eventually die
34
Implantation of embryo
1. cillia lining the inner surface of oviduct sweep the fertilised egg along the oviduct. peristalsis movement in wall of oviduct also helps move zygote to uterus
2. zygote divides by mitosis to form a ball of cell called the embryo. energy needed for this is provided by the nutrients stored in the egg. It takes about 5 days for the embryo to reach the uterus and it may float freely in uterus for about 2 days
3. embryo gets embedded in uterine lining. (Implantation). Implantation usually occurs 7 days after fertilisation
35
Development of placenta
4. After implantation, villi begin to grow from embryo into uterine lining and they contain blood capillaries for embryo
5. the villi and uterine lining that it is embedded into forms the placenta
6. the umbilical cord attaches the embryo to the placenta
36
Development of amniotic sac
7. a membrane called the amniotic sac begins to develop around the same time as the placenta
8. amniotic sac encloses the embryo in a fluid-filled space known as the amniotic cavity. the fluid is the amniotic fluid
9. embryo continues to develop. about 10 to 12 weeks after fertilisation, all major organs have been formed and a fetus is created
37
Functions of Placenta
- allows oxygen and dissolved food substances, such as glucose, amino acids and mineral salts, to diffuse from the maternal blood into the fetal blood
- it allows metabolic waste or excretory products, such as urea and CO2, to diffuse from fetal blood into maternal blood
- allows protective antibodies to diffuse from the maternal blood into the fetal blood to protect it against certain diseases
- produces oestrogen and progesterone which maintain uterine lining in healthy sate during pregnancy
38
Functions of umbilical cord
- attaches fetus to the placenta
- umbilical cord cord contains the blood vessels of fetus
- contains 2 umbilical arteries that transport deoxygenated blood and metabolic waste products from fetus to placenta
- contains 1 umbilical vein that transports oxygenated blood and food substances from the placenta to the fetus
39
Functions of the amniotic fluid
- supports and cushions the fetus before birth by being a shock absorber since it cannot be compressed, protecting fetus from physical injury
- allows fetus a certain degree of movement, promoting muscular development
- it lubricates and reduces fiction in the vagina/birth canal during birth
40
Why the fetal blood system is not continuous with the maternal blood system
- blood pressure of other will kill fetus as it is much higher than that of fetus
- blood group of fetus and mother may be different, this may cause agglutination of blood cells of both fetus and mother, which can be dangerous for the both of them
- prevents potential harmful substances or pathogens from directly entering fetal bloodstream (But diseases can still transfer from mother to child)
41
What is HIV
- Human Immunodeficiency Virus (HIV)
- it destroys a person's immune system by destroying white blood cells
- HIV may develop into AIDs (Acquired Immune Deficiency Syndrome)
42
Signs and symptoms of AIDs
- pneumonia
- brain infection
- chronic/persistant fever
- wide spread tuberculosis affecting many organs at the same time
- severe diarrhoea lasting for months
- Cancer of blood vessels
43
How HIV is transmitted
- sexual intercourse w/ infected person
- sharing of hypodermic needles with infected person (unsterilised needles)
- blood transfusion with blood from infected person
- through pregnancy from mother to fetus
44
How we can prevent and control HIV transmission
- keep to 1 sexual partner/abstain from sexual intercourse
- males should wear condoms
- don't share instruments that are likely to break skin & be contaminated with blood (Ex: razors)
- go to reliable operators for tattoos, acupuncture, ear-piercing, & ensure that the needles are sterilised
