Reproduction in Humans Flashcards
State and identify functions of male reproductive systems (parts of the system)
- Testicles: produce male gametes - sperms
- Scrotum: a sac that keeps testes cool
- Sperm ducts: link testis to urethra: allow passage of semen containing sperm
- Prostate gland: produce alkaline fluid -> semen
- Urethra: urinate; pass semen (+sperm) through penis
- Penis: become firm, inserted into vagina during sexual intercourse -> transfer sperm
State and identify functions of female reproductive systems (parts of the system)
- Ovaries: contains follicles, produce
and stores eggs, produce oestrogen - Oviducts: carries ovum to uterus; Fallopian tubes = site of fertilisation
- Uterus – where fetus develops
- Cervix- a ring of muscles that separate the vagina from the uterus
- Vagina: receives sperm from erect penis during intercourse
Compare male and female gametes in terms of size, numbers and mobility
- Sperms: \+ Size: small \+ Movement: swims using tail (flagella) \+ Food store: has very little - uses sugar in seminal fluid \+ Number of chromosomes: 23 \+ Number produced: millions - Eggs: \+ Size: large \+ Movement: along the oviduct by cilia and peristalsis \+ Food store: protein and fat in cytoplasm \+ No. of chromosomes: 23 \+ Number produced: once a month
Explain the role of hormones in controlling
the menstrual cycle (including FSH, LH, progesterone and oestrogen)
- FSH: released from pituitary gland. Stimulates the development of follicle
- Oestrogen: released from follicle. Lining of uterus thickens, triggers LH
- LH: released from pituitary gland. Triggers ovulation
- Progesterone: released from the yellow body. Maintains uterus lining
Describe the menstrual cycle in terms of
changes in the uterus and ovaries
- During a menstrual cycle a follicle (small groups of cells + potential egg) develops inside the ovary and the lining of uterus thickens.
- Follicle grows and enlarges => bursts releasing eggs = ovulation. Follicle cells left behind = yellow body
- If implantation does not occur => lining of uterus breaks down
- One egg is released every month
Outline sexual intercourse
involves inserting the erect penis into the vagina.
- When stimulated, spongy tissue in the penis filled with blood and becomes erect.
- At the climax, semen is ejaculated from the penis into the neck of the vagina.
- Contractions of urethra help to propel the semen forward
- The sperms with their tails swim from the vagina, through the cervix and uterus into the oviduct
- Fluid made by vagina wall lubricates the movement of the penis
Describe fertilisation
the fusion of the nuclei of male gamete (sperm) and the female gamete (egg), to form a zygote
How is sperm adapted to its function?
- Acrosome releases enzymes to digest pathway through the jelly coat surrounding the egg
- Has tail => swims faster
- Has mitochondria which releases energy to power swimming of the tail
How is an egg adapted to its function?
- Has a large food store to last until implantation, provide food for embryo
- Forms membrane when fertilised so that no other sperm cells can enter
Outline early development of the zygote
Divides (by mitosis) once to form a 2-celled embryo. Then four, then eight. Cycle of divisions become less regular forming a ball of cells (embryo) that moves down the oviduct by peristalsis and becomes implanted in the wall of the uterus
Outline the development of the fetus
- 4 weeks: the heart is beating
- 8 weeks: it has a face, limbs, fingers and toes
- 16 weeks: fetus starts to kick
Describe the function of the umbilical cord
- Umbilical cord:
+ joins fetus to placenta; contains:
+ 2 arteries: blood from fetus -> placenta
+ 1 vein: returns blood -> fetus
Describe the function of placenta
- Blood from the fetus passes through the umbilical cord in the umbilical artery to the placenta.
- Here it comes close to the mother’s blood.
- transport O2 + nutrients (amino acids, glucose…) from mother -> fetus
- transport CO2 + wastes (urea… ) from fetus ->mother (through umbilical vein)
- prevents mother’s and child’s blood from mixing
Indicate the functions of the amniotic sac and
amniotic fluid
- Amniotic sac: membrane from embryo cells: encloses fetus, prevents entry of bacteria
- Amniotic fluid: supports, protects fetus from mechanical
damage; absorbs urine released by fetus.
Describe the ante-natal care of pregnant women
including special dietary needs and maintaining good health
- amino acids -> healthy grow and development
- calcium -> development of the skeleton
- iron -> red blood cell formation
- energy (carbohydrates/ fats) – help to move mother’s heavier body.
- gentle exercises
- avoid
+ drugs: aspirin, heroin
+ smoking: nicotine and CO
+ alcohol drinking
Describe the advantages and disadvantages
of breast-feeding compared with bottlefeeding using formula milk
- Advantages
+ Children are less likely to develop certain diseases
+ Mother is less likely to develop breast cancer
+ Always in the perfect temperature - Disadvantages:
+ Embarrassing
+ Diseases from mother will be passed down to the child
Outline the processes involved in labour and birth
- Oxytocin is triggered
- Muscular walls of uterus start to contract
- Pressure breaks amniotic sac
- Contractions become more frequent, pushes baby down to the cervix
- Cervix becomes dilated and vagina stretches
- Baby passes out
- Umbilical cord is cut and tied
Describe the roles of testosterone in the development and regulation of secondary sexual characteristics at puberty
- Voice becomes much lower (breaks)
- Hair start to grow on chest, face,
- under arms and in pubic area
- Penis becomes larger
- Testers start to produce sperm
Describe the roles of oestrogen in the development and regulation of secondary sexual characteristics at puberty
- Breasts grow, nipples enlarge
- Hair develops under arms and in pubic area
- Hip become wider
- Uterus and vagina become larger
- Ovaries start to release eggs and period begin (menstruation)
Natural methods of birth control
- Abstinence (no sex)
- Rhythm method (calendar)
Mechanical methods of birth control
- Condoms
- Diaphragm (rubber dome that is placed over the cervix before sex)
- IUD (placed in the uterus)
Surgical methods of birth control
- Vasectomy (sperm tubes are cut and tied)
- Sterilisation (oviducts are cut and blocked)
Chemical methods of birth control
- Contraceptive pills (prevents ovary from releasing eggs)
- Spermicide
Outline artificial insemination and discuss their
social implications
- An artificial insemination procedure uses a thin, flexible tube (catheter) to put sperm into the woman’s reproductive tract (vagina, cervix, uterus) around the time of ovulation.
- The man has to be able to accept that the child is not biologically his
- When the child grows up, he may wants to know who his biological father is. Some people think that the identity of the sperm donor should be given
to the child.
Outline the use of hormones in fertility drugs, and discuss their social implications
- Fertility drugs are used when the woman is notproducing enough eggs. She is given hormones, including FSH and LH, that cause multiple release of
eggs. - Sometimes 2 or 3 embryos develop, so the couple might have twins or triplets when they really only wanted one child.
Describe the symptoms, signs, effects and treatment of gonorrhoea
- Symptoms:
+ Male: sores on penis, pain when urinating
+ Female: usually no symptoms - Effects:
+ Damage to urinary and reproductive organ
+ Sterility
+ Blindness in a baby born to a mother with the disease - Treatment: antibiotics (penicillin)
Describe the methods of transmission of human (HIV)
- unprotected sexual intercourse with infected person
- drug use involving sharing needle used by infected person
- transfusion of infected blood
- infected mother to fetus
- feeding a baby with milk from an infected mother
- unsterilised surgical instruments
Ways in which HIV/AIDS can be prevented from spreading
- condom for sexual intercourse
- use sterilized needles
- feed baby with bottled powdered milk (if mom has HIV)
- use sterilised surgical instruments.
Outline how HIV affects the immune system in a person with HIV/AIDS
- Lymphocytes produce antibodies -> attack the antigens on invading microbes.
- Some lymphocytes are stored in lymphocytes nodes —> protection against future infection
- HIV prevents this immunity being retained and attacks on lymphocytes
