Sexual Reproduction in Humans Chp41 Flashcards
What is a gonad
an organ that produces sex cells in animals
What are the parts in the male reproductive organ
scrotum, urethra, testis, epididymis, sperm duct, seminal vesicle, prostate gland, cowper’s gland
What is the function of the testes
produce sperm
What is the function of the epididymis
store sperm cells and mature them
What is the function of the sperm duct
carries sperm to urethra
What is the function of the urethra
carry sperm and urine
What is semen
a fluid containing sperm and seminal fluid
What is the function of the seminal vesicles, prostate gland and cowper’s gland
produce seminal fluid which provides a medium for sperm t swim and nourishes the sperm
What is the structure of a sperm cell
acrosome, nucleus (head), collar (midpiece), flagellum (tail)
What is the function of the acrosome
contains enzymes that digest the membrane of the egg
What is puberty
the beginning of sexual maturity
What is the swollen tip of the penis called
the glans
What are the hormones associated with the male reproductive system
FSH (follicle stimulating hormone), LH (luteinising hormone)
What is the function of FSH (males)
causes diploid sperm-producing cells in the testes to divide by meiosis and produce haploid sperm
What is the function of LH (males)
stimulates the testes to produce testosterone
What are secondary sexual characteristics
features that distinguish males from females apart from sex organs themselves
Examples of secondary male characteristics
growth of body hair, growth spurt, widening shoulders
What is infertility
the inability to produce offspring
What is a male infertility disorder
low sperm count
What is a cause for low sperm count
use of drugs, stress, abnormal sperm production
What is a treatment for low sperm count
change in diet, reduce stress, change drug consumption
What are the parts in the female reproductive system
ovaries, fallopian tubes, uterus, vagina, cervix, vulva, endometrium
What is the function of the ovaries
produce eggs and female hormones
What is the function of the fallopian tubes
moves the egg along to the uterus and egg is fertilized here
What is the function of the uterus
where the embryo and baby develop
What is the cervix
the opening of the uterus
What is the function of the endometrium
nourishes the embryo in the event of a pregnancy
What is the function of the vagina
allows the entry of sperm and allows the baby to exit
What is ovulation
the release of an egg from the ovary
What is the menstrual cycle
a series of events that occurs every 28 days on average in the female if fertilisation has not taken place
What is menopause
when ovulation and menstruation stops happening in a female
What happens day 1-5 in the menstrual cycle
FSH produced by the pituitary gland, endometrium breaks down and is shed, meiosis occurs in ovary to produce new egg surrounded by the Graafian follicle
What happens day 6-14 in the menstrual cycle
Graafian follicle produces oestrogen causing endometrium to thicken, and prevents new eggs from developing
What happens day 14 in the menstrual cycle
LH is produced by the pituitary gland, ovulation occurs when Graafian follicle bursts to release egg from ovary, the egg passes into the fallopian tube and is available for fertilisation for up to 48 hours
What happens day 14-28 in the menstrual cycle
remains of Graafian follicle develop into the corpus luteum and makes progesterone, which thickens endometrium more, hormone stops new eggs from forming
What is menstruation
the discharge of the lining of the uterus and the unfertilised egg
What are the functions of oestrogen and progesterone
oestrogen causes endometrium to thicken in first half, progesterone continues this and both prevent new eggs from developing
What are secondary female characteristics
the maturing and enlargement of the breasts, widening of the pelvis, growth spurt
What is an example of a menstrual disorder
fibroids
What is a treatment for fibroids
surgery/ hysterectomy
What is a female infertility disorder
blockage of the fallopian tubes
What is a cause for blockages in the fallopian tue
fragments of uterus lining spread to fallopian tube
What is a treatment for female infertility
IVF (In-Vitro-Fertilisation)
What is copulation
the act of sexual intercourse
What is an orgasm
the physical and emotional sensations experienced at the peak of sexual excitement
What is ejaculation
the release of semen from the penis
What is insemination
the release of semen into the vagina, just outside the cervix
What are the stages of copulation
sexual arousal, copulation, orgasm
What is chemotaxis
when the sperm cells swim towards the chemicals produced by the egg
What is ferilisation
when the nucleus of the sperm fuses with the nucleus of the egg, forming a diploid zygote
What are the events leading to fertilisation
insemination, sperm swim towards egg, sperm swarm the egg, one sperm head enters the egg, fertilisation membrane forms, fertilisation
What are the survival times for sperm and eggs
sperm-7 days, egg-2 days
What is implantation
the imbedding of he fertilised egg into the lining of the uterus
What is IVF
involves removing eggs from an ovary and fertilising them outside the body
What 2 tissues form the placents
embryonic and uterine tissue
Describe placenta formation
soon after implantation the chorion surrounds the amnion and embryo, the combination of the chorionic villi and the endometrium forms the placenta
What are the functions of the placenta
exchange of gases, nutrient, waste, antibodies and prevents bloods from mixing and produces hormone progesterone
What is a morula
a solid ball of cells formed from a zygote by mitosis
Describe the early development of the zygote day 1
fertilisation occurs on day one, zygote has 46 chromosomes half from sperm and half from egg
Describe the early development of the zygote day 3
during first 3 days zygote divides rapidly producing a solid clump of cells called the morula
Describe the early development of the zygote day 5
the morula forms a hollow ball of a few hundred cells called a blastocyst, outer cells form the trophoblast and inner cells will later form the embryo, blastocyst is pushed into the uterus
What is a blastocyst
a hollow ball of cells formed from a morula
What are germ layers
basic layers of cells in the blastocyst from which all adult tissues and organs will form
What are the 3 germ layers
ectoderm, mesoderm, endoderm,
Describe embryonic development day 10
inner cell mass of the blastocyst form 3 germ layers with each germ layer forming different structures
What does the ectoderm layer produce
skin , nails, hair, nervous system
What does the mesoderm layer produce
muscles, skeleton, respiratory system, reproductive system
What does the endoderm layer produce
inner lining of digestive system, respiratory system, and liver and pancreas
Describe embryonic development up to 8 weeks
the heart forms and starts to beat in the embryo in the first 4 weeks, the brain develops and umbilical cord forms, week 5 limbs and internal organs start to form, 6 weeks eyes, mouth, nose, ears form, embryo is called a foetus
Describe embryonic development up to 3 months
grows and refines structures already formed, last 7 months involve the growth of the foetus no more organs are produced
What is gestation
the length of time spent in the uterus from fertilisation to birth
What are the hormones associated with birth
progesterone and oxytocin causes contractions resulting in the onset of labour
What are the stages of birth
Stage 1: lasts about 12 hours, contractions push foetus down towards cervix, mucous plug expelled, membranes around foetus break/water breaks. Stage 2: 20 mins-1 hour, cervix dilates, foetus is pushed through the cervix head first, umbilical cord cut. Stage 3: placenta and foetal membranes are expelled
What is lactation
the secretion of milk by the mammary glands of the female
What is prolactin
hormone produced by the pituitary gland which stimulates milk production
What is a biological benefit of breastfeeding
ideal balance of nutrients for baby, provides supply of antibodies
What is birth control
methods taken to limit the number of children that ae born
What is contraception
the deliberate prevention of fertilisation or pregnancy
What is a method of natural contraception
avoid having intercourse when pregnancy is possible in the menstrual cycle
What is a method of mechanical contraception
condoms
What is a method of chemical contraception
hormones such as progesterone and oestrogen taken to prevent ovulation (the pill)
What is a method of surgical cotraception
vasectomy in males and sterilisation in females
