chp 15 & 16

Question 1

gonads

Answer 1

primary sex organs

produce gametes

Question 2

other secondary sex organs

Answer 2

store gametes
bring them together for fertilisation
support developing baby

Question 3

testes

Answer 3

male gonad, oval shaped
produces spermatozoa
held and supported in aa skin covered pouch, scrotum, internally divided into 2 sacs each containing a single testis
testes lay outside body cavity because production of sperm a temperature that is 2º less than the regular body temperature. contraction of smooth muscle fibre in scrotum wall, moves testes closer to body at a higher temp. Relaxing fibres moves testes away, making it cooler.

divided into around 200 and 300 lobules filled with fine tubes called seminiferous tubules. tubules are lined with cells that make sperm. clusters of interstitial cells between tubules secrete testosterone

Question 4

epididymis

Answer 4

the seminiferous tubules in each tubule/compartment of a testicle join to gather to form a short straight tubule. straight tubule eventually join into ducts which leave the testicle and lead to the epididymis

highly folded tubule at the rear surface of each testis. unraveled= 5-6m, allows for lots of space for sperm storage, can be held form months, during this time, sperm mature

Question 5

vasa deferentia

Answer 5

tubule of epididymis continues to become the vasa deferentia. carries sperm away from testis. loops behind the bladder and under the bladder the two tubes going the urethra.

Question 6

seminal fluids

Answer 6

nourishes and aids the transport of sperm, semen contains enzymes that activate sperm once ejaculation takes place.

1. seminal vesicle: pair of vesicles behind the bladder. secrets a thick fluid rich in sugars, makes up 60% of semen volume.
2. prostate gland: surrounds urethra below bladder. secretes a thin milky alkaline fluid that becomes part of semen
3. bulbo-urethral glands: pea sized small yellow glands, behind prostate on either side of the urethra. secrete clear mucus which is carried to the urethra by a duct from each gland. act as a lubricant, only a small amount in semen

Question 7

erectile tissue

Answer 7

penis contains connective tissue very rich in blood supply

the erectile tissue has a large number of sponge like spaces that fill with blood when sexually aroused (erection)

Question 8

ovaries

Answer 8

each side of abdominal cavity, supported by ligaments
composed of a mass of connective tissue called stroma, which is surrounded by a layer of cells including germ cells (gametes)
each germ cell is enclosed in a follicle, numerous follicles are at different stages of development at any time. as a follicle matures, it moves to the surface of the ovary and ruptures

Question 9

fallopian tubes

Answer 9

egg is expelled into funnel like opening of FT
2 FT, one extending from each ovary
carry egg from ovary to uterus

fimbriae: funnel like opening of FT is lined with finger like projections that appear to touch the surface of ovary. help guide the egg into tube

ciliated epithelium lines the tube. beating cilia and contractions of smooth muscle that lines the tubes help the egg move.

Question 10

uterus

Answer 10

pear shaped organ behind the bladder, in front of rectum
held in position by broad ligaments, they don’t hold the uterus tightly in place, has limited movement so position can vary slightly
wall is made of smooth muscle with a soft mucous membrane lining (endometrium)
protects and nourished foetus during pregnancy

Question 11

cervix

Answer 11

lower end of uterus, protrudes into vagina

Question 12

vagina

Answer 12

muscular structure lined with mucus membrane, capable of considerable stretching
external opening of vagina is partially covered by a fold of tissue (hymen)
vulva (external genitals)= labia majora+labia minora +clitoris

Question 13

labia majora & minora & clitoris

Answer 13

labia majora:
fleshy fold of skin made of fat and fibrous tissue. glands that produce oily secretions. outer part is hairy, inner part is smooth

labia minora:
smaller folds of skin, beneath and between the labia majora. surrounds external opening of vagina and urethra

clitoris:
contains erectile tissue, blood vessels and nerves
engorged with blood when stimulated

Question 14

meiosis

Answer 14

production of gametes with half the number of usual chromosomes, makes 4 daughter cells
occurs in gonads
involves two nuclear divisions but chromosomes duplicate only once

Question 15

meiosis 1

Answer 15

during interphase DNA is copied
Prophase 1:
chromosomes become visible as two chromatids
homologous pairs lie next to each other
crossing over occurs (exchange of genes)
spindle fibres form and nuclear membrane disappears

Metaphase 1:
paired homologous chromosomes line up along equator
independent/random assortment of maternal and paternal
spindle fibers attach to each

Anaphase 1:
pairs separate and homologous move to poles (23 each side)

Telophase 1:
nuclear membrane reforms around 23 chromosomes cytoplasm divides in two
2 haploid daughter cells with a different combination of maternal and paternal genes

Question 16

meiosis 2

Answer 16

interphase is skipped
Prophase 2:
centriole migrate and new spindle fibres form
nuclear membrane disappears

Metaphase 2:
chromosomes move to equator and line up
spindle attaches to chromosomes

Anaphase 2:
chromatids spilt and move to poles

Telophase 2:
nuclear membrane reforms
cytoplasm divide

Question 17

spermatogenesis

Answer 17

seminiferous tubules of each testis are lined with immature cells called spermatogonia (diploid)
at puberty the spermatogonia divide by mitosis to make continuous source of new cells for the production of sperm.
Some daughter cells are pushed to the centre of the tubule where they undergo a period of growth. These enlarged cells other primary spermatocyte. They are diploid and undergo meiosis 1 to form secondary spermatocytes (haploid). secondary meiosis occurs which divides the secondary spermatocyte into two spermatids. 4 haploid cells produced.

spermatids mature in to sperm for the final stage. much of cytoplasms, of cells is lost and a tail made of contractive material is formed. nourished by special cells
takes 72 days and occurs continuously after puberty

Question 18

sperm structure

Answer 18

head: contains nuclear material, with a fluid filled vesicle at the tip. contains enzymes that breaks down ovum’s outer layer
middle: contains mitochondria, allows respiration take place to produce energy for sperm to move. has a little cytoplasm, so has a short life.
tail: capable of violent swimming to propel cell forward

Question 19

oogenesis

Answer 19

before birth millions of oogonia develop in ovaries. decreases to several 100 thousand at birth which have undergone a growth phase to make primary oocytes, they begin prophase 1 but stops there. each primary oocyte is surrounded by a primary follicle.

puberty:
follicle growth and maturation begins
as follicle matures, the primary oocyte complete meiosis 1, producing two haploid cells that are unequal in size. one secondary oocyte (half chromosomes but almost all the cytoplasm) and first polar body.
secondary meiosis is commenced by the secondary oocyte but stops at metaphase 2 (ovulation occurs at this stage). follicle ruptures expelling secondary oocyte and polar body. SO enters FT and if fertilised, meiosis 2 is completed. meiosis 2 also makes two unequal cells. larger one develops into an ovum and smaller one is the second polar body. first polar body may divide, however all polar bodies disintegrate

Question 20

ovarian cycle

Answer 20

series of events in ovaries
maturation of egg and release into tube
development of follicle and corpus luteum
20 - 40 days (28 average)

cells in ovaries undergo many divisions but stop dividing before and ovums are actually formed
other cells within the ovary surround each immature egg to produce a sphere composed of a single layer of cells (primary follicle)

Question 21

events leading to ovulation

Answer 21

at puberty
some primary follicles undergo further development
cells forming wall of follicle begin to enlarge and divide creating a layer of cells around the developing egg
secretions of these cells creates a fluid filled space that gradually forces the egg to the edge of the follicle, forming the secondary follicle.

several secondary follicles may commence development in each cycle but only one completes development, others may breakdown to be reabsorbed into ovary.

as more fluid accumulates within the follicles, it continues to enlarge and gradually moves to the surface of the ovary. on reaching the surface it creates a bulge that looks like a blister. follicle is now a Graafian follicle (mature).

takes 10-14 days to make a mature follicle from a primary follicle. when mature follicle bursts, it expels the egg in a process called ovulation

Question 22

after ovulation

Answer 22

ruptured follicle collapses and blood within forms a clot. the clot gradually absorbed by the remaining follicle which enlarge sand changes colour to a cream, corpus luteum.
corpus luteum secrets progesterone for endometrium

Question 23

if fertilisation doesn’t occur

Answer 23

CL reaches max development 8-10 days after ovulation, and begins to degenerate intro fibrous mass of scar tissue, corpus albicans which eventually disappears

cycle begins over again. from which ovary the egg come is up to chance

Question 24

if fertilisation occurs

Answer 24

CL continues to develop and cycle ceases. CL reaches peak development in the 3rd month, so it slowly begins to degenerate then. cycle resumes after breastfeeding stops

Question 25

menstruation

Answer 25

if the egg isn’t fertilised, CL degenerates which leads to a decrease in progesterone, so endometrium breaks down.
blood from broken down capillaries, mucous secretions and cell debris from uterus lining is lost through vagina. and shedding of endometrium

Question 26

FSH

Answer 26

in females: stimulates development and maturation of the ovarian follicle. during its development, the follicle secretes oestrogen. as oestrogen increase in blood, FSH decreases

in males: stimulates epithelial tissue of seminiferous tubules in testes to produce sperm

Question 27

LH

Answer 27

in males: targets interstitial cells of testes to stimulate secretion of testosterone

in females: promotes final maturation of the ovarian follicle, ovulation and production of CL. stimulates secretion of oestrogen and progesterone

Question 28

oestrogen

Answer 28

development if female reproductive system

development of secondary sexual characteristics

Question 29

progesterone

Answer 29

CL secrets progesterone. there is a gradual decrease in LH as progesterone decreases. maintains the endometrium, development and maintenance of the placenta, and development of milk secreting glands

Question 30

testosterone

Answer 30

important in developing immature sex cells into mature sperm

sex drive

Question 31

sex

Answer 31

rhythmic of epididymis, prostate gland, vas defers and seminal vesicle lead to ejaculation

erectile tissue in region of vaginal opening fills with blood which reduces size of vaginal opening.
secretion of mucus by glands surrounding cervix and vaginal opening lubricate lining of vagina

Question 32

fertilisation

Answer 32

only few 1000 reach the FT
high sperm mortality is why there is a lot

ovum: surrounded by a layer of follicle cells (corona radiata ) cells are held together by acid.
several thousand sperm need to loosen the cells of corona allowing one sperm to complete fertilisation. forms fertilisation membrane which prevents other sperm to enter.

tail is absorbed and head forms male pronucleus. meiosis finishes and nucleus of egg forms the female pronucleus which fuses with the male pronuclei to form a diploid nucleus (zygote)