REPRODUCTION Flashcards
why is sex the used method of reproduction
- produces less offspring, but far more genetic diversity
- populations are better suited to persist in the face of pressures
what is gametogenesis
the process of gender being selected by combination and randomization
What is the purpose of meiosis
- producing haploid gametes (half chromosomes) so that may join to have half and half genetic info
what is fertilisation
the combination of chromosomes and genes of two haploid gametes
explain the haplo-diploid life cycle
helps to draw it out
- mature individual produces sperm or eggs = spermatogenesis and oogenesis
EMBRYOGENESIS: - fertilization occurs
- cleavage/mitosis for growth
- gastrulation (sphere of cells)
- neurulation
- organogenesis - develop organ
- cytodifferentiation - specialised cells (blood)
- individual life, growth then maturation
how is sex determined
- chromosome/genetically determined XY and XX
- environmentally - temperatures in oviparous reptiles (turtles)
- hormones
What is the SRY gene
a single gene on the Y chromosome that dtermines maleness, causes fetal gonad to develop into testis when switched on
What is DHT
- dihydrotestosterone
- causes androgenic effects where the concentrations of testosterone are too low to be effective, must be
- would result in a female phentoype if male were lacking the enzyme 5-alpha reductase
what is androgen insensitivity syndrome
- androgens are present but receptor is faulty so female phenotype occurs but is weak. some features missing - cervix
- causes undescended testes
What is hermaphordite
- one gender, but switches gender at some point in its life
Protandry = male then female
protogyny = female then male
what is intersex
genotype, phenotype or hormones that are both male and female related at the same time
explain sperm development
draw and label
- spermatogenesis = meiosis to form spermatid
- spermiogenesis = maturation of spermatic to sperm.
- Acrosomal vesicle releases conttents to digest materials around egg - Capacitance of sperm - remove cell surface
explain egg development
- Oogenesis - meiosis and cellular maturation
starts and stops during foetal development - Resumes at puberty
- maturation creates large cell - ovarian follicle and protective coverings form to completely maturation
differences between male and female gamete production
male:
- some mitotic proliferation early
- meiosis starts at puberty and continues for life
- many more devisions
- products of meiosis are all the same
- no male menopause
female:
- lots of germ cell proliferation in fetal life
- meiosis starts in fetus, suspends, then begins at puberty
- born with all germ cells they can use
- meiosis unequal: 1 large oocyte and 3 small residual polar bodies?
- menopause
adaptations of reproduction in each sex
male: fast swimming sperm, not picky about mate, many sperm
female: few gametes so is picky about mate
intra vs intersexual competition
intra: same sex competing - causes different phenotypes to appear more attractive
inter: between different sexes - trying to get a mate
what is a vomeronasal organ
- can detect when a mate is breeding ready
primary and accessory glands of males
primary sex organ = testes
accessory glands = complex set of ducts and tubules from testes to penis
organ of copulation = penis
What are the functions of the testes
- sperm production
- secrete hormone testosterone
explain the structure of testes
- tunica albuginea projects internally into testes to form septa
- septa divide into 250 lobules
- each lobule contains 4 convoluted seminiferous tubules
- seminiferous tubules contain sustentacular cells (do NOT divide, form a blood- testis barrier), and dividing germ cells to form sperm
why is the blood-testis barrier required?
- to stop anti-sperm antibodies forming in blood and destruction of sperm cells
draw and label a testes
- ductus deferens
- efferent ductule
- epididymis
- seminiferous tubule
- septum
- lobule
- tunica albuginea
- tunica vaginalis (visceral vs parietal)
- spermatic cord
what is the scrotum
- skin covered sac that houses testes
- keeps testes cool (3° below body temp)
What does the spermatic cord consist of
- originates at the inguinal canal
1. testicular artery
2. pampiniform plexus- veins that surround artery
3. cremaster muscles and fascia - muscles that raise and drop testes to change temperature
4. autonomic nerves - connect to testes
name and role of ducts in male repro system
- rete testes -> move sperm into epididymis
- efferent ductules - absorb fluids from sperm
- epididymis - transport sperm from testes to the vas deferens, store sperm, matures sperm
- ductus deferens - transport sperm to urethra
- ejaculatory duct - adds secretions, deliver sperm into urethra
- urethra - excretion of sperm
draw and label male reproductive system
- urinary bladder
- ureter
- testis
- epididymis
- ductus deferns
- seminal vesicle - produce seminal fluids
- prostate gland - more seminal fluids for semen
- bulbourethral gland - more seminal fluids, mucin for lubrication
- corpus cavernosum - outer lining of penis/urethra
- corpus spongiosum - inner lining of penis/urethra
- glans - end of penis (prepuce = foreskin on top)
ejaculatory duct
what does the ductus deferens do
travels with spermatic cord
- during ejac, peristalsis of smooth muscle in walls will propel sperm along
what do seminal fluids do
- nourish sperm and neutralise pH of vagina
functions of the penis
- intercourse
- urination
what are the 3 erectile bodies of the penis
- 2 corpus cavernosum
- 1 corpus spongiosum
- spongy urethra
how does an erection occur
- erectile bodies have venous spaces which fill with blood from artery
how does ejaculation occur
- rhythmic contraction of smooth muscles of urethra and ductus deferens
- sphincter of bladder closes
what are the functions of the female reproductive system?
- produce an ovum
- facilitate transport of sperm to ova
- provide nourishment for developing embryo
- provide passage for birth
- provide nourishment for young
What are some reproductive homologues between males and females
- testes and ovaries poduce gametes and sex hormones
- clitoris and glans are stimulates for arousal and sexual climax
- labia major and scrotum are both protective coverings of repro surfaces
- vestibular glands and bulbourethral glands - secrete mucin for lubrication
organ and accessory organs of female
primary organ = ovaries
accessory organs:
- uterine tubules
- uterus
- vagina
- clitoris
- mammary glands
explain structure of an ovary
- surrounded by connective tissue capsule called tunica albuginea
- under this layer, ovary divided into outer cortex and medulla
- cortex contains ovarian follicles and medulla contains connective tissues (blood vessels, nerves etc)
what are ovarian follicles
- consist of an oocyte and follicle cells
- release egg for fertlisation after maturaton
explain structure of the uterine/oviduct/fallopian tube
many regions
1. fimbrae on end of 2 to catch egg from ovary
2. infundibulum
3. apulla - expanded region, where fertilisation occurs
4. isthmus - attachment to uterus area beginning
what are the 3 wall layers of the uterine tubes
- mucosa = (innermost) ciliated epithelial cells
- muscularis = inner circular layer and outer longitudinal layer of smooth muscle
- serosa - external serous membrane covering tube
explain the process of fertilisation to zygote
- sperm enters uterine tube
- sperm and egg undergo zona reaction and oocyte granules released
- sperm enters oocyte cytoplasm
- fusion and zygote produced
where does the zygote implant
in the uterus’ endometrium layer
what are the layers of the uterus
- muscular wall = myometrium
- external serous membrane - perimetrium
- internal vascular epithelium - endometrium?
label female reproductive system
- uterine tube -> infindibulum, ampulla, isthimus, frimbriae
- ovary
- uterus -> endometrium, myometrium and perimetrium
- cervix + cervical canal
- vagina
ovarian ligament - uterine artery
- vaginal orifice
label female repro anatomy in other animals
- uterine horn
- ovary
- bladder (usually larger)
- uterus (smaller)
- uterine tube/oviduct
- cervix (quite long)
- vagina
- urethra
- mesometrium (thin layer)
what is included in vulva (external)
labia majora (outside)
labia minora (inside)
vestibule
clitoris
urethra and vaginal orifice
what are some ectopic implantation sites
- uterine tube
- cervical opening of uterus
- ovary
- peritoneal lining (near organs)
explain the structure of a growing egg
four layers in amniotes:
1. chorion = outermost layer for gas exchange
2. amnion = surrounds embryo - fluid filled to cushion and for osmoreg
3. allantois = collects nitrogenous wastes
4. yolk = provides nutrition for growth
- albumen = fluid between shell and embryo, provides water and some nutrients for development, and protects against bacteria entering embryo
- shell
what is partuition?
birth
- contractions of smooth muscle of uterus
