Chapter 15 - Production Of Sex Cells Flashcards
What are gametes?
Sex cells
What are gonads?
Organs that produce sex cells
What is a diploid cell?
A somatic cell that contains 46 chromosomes.
What is a haploid cell?
A sex cell that contains 23 chromosomes.
What is the product of mitosis?
Diploids for growth and repair.
What is the product of meiosis?
Gametes for sexual reproduction.
What is a zygote?
The product of fusion of the male and female gametes at fertilisation.
What are the male gametes?
Spermatozoa
What are the female gametes?
Ova
What does sexual reproduction involve?
The joining together of gametes
What are primary sex organs?
The organs that produce gametes.
What are secondary sex organs?
Organs that store gametes, bring them together for fertilisation and support the developing baby
What are the male primary sex organs/gonads?
Testes
Where are the testes located?
In a skin covered pouch called the scrotum which is the supporting structure for the testes
Why do the testes lie on the outside of the body cavity?
Because the production and development of sperm requires a temperature about 2 degrees lower than body temperature.
What happens when the testes are too cold/hot?
Smooth muscles fibres contract to move them closer or further away from the body
What is the structure of the seminiferous tubules?
200-300 lobules
What is the function of seminiferous tubules?
Lined with cells that divide during spermatogenesis to produce male gametes
What is the function of interstitial cells?
Secrete testosterone
What is the function of the epididymis?
Stores sperm and transports in from the testes to the vas deferens
What does sperm require?
- a watery medium in which to swim
- a nourishing environment that provides sugars they need
- protection against the acidic environment of the vagina
What does semen do?
Nourishes and aids the transport of sperm
What is the function of the vas deferens?
Carries sperm away from testes and connects with the urethra
What is the function/structure of the seminal vesicles?
- pair of pouch like glands
- secrete a thick, sugary fluid that makes up 60% of sperm
What is the structure/function of the prostate gland?
- single gland, shaped like a donut
- where the two vas deferens join the urethra
- secretes a thin, milky, alkaline fluid that also becomes part of semen
What is the function/structure of the bulbo-urethral glands?
- two small yellow glands the size of a pea
- secretes clear lubricating mucus
- much of the secretion precedes the emission of seminal fluid
What is the glans covered by?
The foreskin
What does the penis contain?
Connective tissue called erectile tissue
What are the functions/characteristics of erectile tissue?
- rich blood supply
- has a large number of sponge like spaces
- during intercourse the spaces fill with blood which causes the penis to stiffen, enlarge and become erect
What is the function of the ovaries?
Produce ova and hormones
What is each ovary composed of?
A mass of connective tissue called stroma, which is surrounded by a layer of cells containing numerous germ cells
What are germ cells enclosed in?
A follicle
What is the function of the uterus?
Holds, protects and nourishes the developing baby during pregnancy
What is the function of the cervix?
Directs sperm into the uterus during interocurse
What is the function of the vagina?
Receives the penis during intercourse and acts as a birth canal
What is the function of the labia minora?
Surround the space into which the vagina and urethra open
What is the function of the labia majora?
Contains glands that produce an oily secretion
What is the function of the clitoris?
Contains erectile tissue that becomes engorged when stimulated
What is the function of the uterine tubes?
Carries eggs from the ovaries to the uterus
What is the function of the fimbriae?
Directs ova into the uterine tubes
What holds the ovaries in place?
Ligaments
What are the seminiferous tubules lined with?
Immature cells called spermatogonia
What happens to spermatogonia at puberty?
They begin to divide by mitosis and in doing so provide a continuous source for the production of new sperm
What happens to the daughter cells of spermatogonia before they undergo spermatogenesis?
They are pushed inward to the centre of the tubule, where they undergo a period of growth
What are primary spermatocytes?
Cells that undergo the first stage of meiosis to produce secondary spermatocytes
What is the final stage of spermatogenesis?
When the spermatids mature into spermatozoa
When does spermatogenesis start occurring?
At puberty
How long does spermatogenesis take?
From spermatogonium to spermatozoa, 72 days
What are egg mother cells called?
Oogonia
What are primary oocytes surrounded by?
Primary follicle
What is the order of the development of ova?
Oogonia - primary oocyte - secondary oocyte - ootid - mature ovum
That are the products of the primary oocytes dividing in the first stage of meiosis?
- secondary oocyte
- first polar body
(Two cells unequal in size)
What does the secondary oocyte immediately start to do?
Commences the second division of meiosis, stopping at metaphase.
At this stage the follicle ruptures and ovulation occurs, and if fertilisation occurs the final meiosis division occurs, producing a mature ovum
