Ch 46 Flashcards
What is Sexual Reproduction?
Creating of an offspring by fusion of haploid gametes (Male sperm and female egg) to form diploid zygote
What is Asexual Reproduction?
Creation of offspring without the fusion of egg and sperm
What are the 4 types of asexual reproduction
1) budding
2) binary fission
3) fragmentation
4) parthenogenesis
What is Budding?
New individuals arise from outgrowths of existing ones
- only in invertebrates
What is Binary Fission?
Separation of parent into individuals of same size
What is Fragmentation?
Breaking of the body into pieces that develop into adults
- Must be accompanied by regeneration
What is Parthenogenesis?
Development of a new individual from an unfertilized egg (2n)
Negative side of sexual reproduction
Finding partner can be tough :(
What is Hermaphroditism?
Each individual has both male and female reproductive systems
Some species can self fertilize
What is True sex change?
Organisms can change their sex under certain circumstances
What is Synchronous hermaphroditism?
Individual simultaneously male and female
What is Sequential hermaphroditism?
sex change
Egg producers become sperm producers (name)
Protogynous
Sperm producers become egg producers (name)
Protandrous
characteristics of Psuedo-penis (3)
1) Hyenas have (pseudophalluses)
2) Paired with “testicles” - fused labia with fatty tissue -
3) Females give birth through their pseudopenis
Most animals exhibit reproductive cycles related to?
Changing Season
What are reproductive cycles controlled by
Hormones and environmental cues
What is ovulation
Release of mature eggs at the mid point in a female cycle
What causes a decrease in reproductive sucess
Climate change
Several Genera of fishes, amphibians, and lizards reproduce by a form of parthenogenesis that involves?
Doubling of chromosomes after meiosis
What is Psuedo-copulation?
They only produce eggs
No sperm
All females
What is the “twofold cost” of sexual reproduction?
Sexual females have half as many daughters as asexual females (cost of male)
Where is sexual reproduction advantageous in?
Environments were factors change alot
Where is asexual reproduction advantageous in?
Stable environments
What is the definition Fertilization?
Union of egg and sperm
What happens in External fertilziation? what kind of environment can it take place in?
Eggs shed by female are fertilized by sperm in external environment
Needs moist habitat
What is Spawning?
Individuals cluster in the same area to release their gametes into the water at same time
What triggers spawning? (2)
1) Chemical signals
2) Environment cues
Pheromones that are released by the ovum to attract the correct sperm are called?
chemoattractants
What are the benefits of Internal fertilization?
Enables sperm to reach an egg despite dry external environment
What can internal fertilization be influenced by?
Pheromones
What does internal fertilization require?
Requires behavioral interaction and compatible copulatory organs
Internal fertilization (traits)
1) Fewer gametes
2) Higher survivorship of zygotes
3) Provide protection of embryos and care from parents
What are the benefits of shells and internal membrane (2)
1) Protect against water loss
2) protection against physical damage
What are Gonads?
Organs that produce gametes
In organisms without gonads, where do gametes form?
undifferentiated tissue
What do accessory tubes and glands do for embryos (3)
1) Carry
2) Nourish
3) Protect
What is Spermatheca?
In Female insects
Sperm is stored during copulation
what is the Cloaca?
Common opening between external environment and digestive, excretory, and reproductive systems
Common in nonmammalian vertebrates
What is monogamy?
Male or female of species have mechanism to decrease chance of mating with another individual
What is pair bonding?
where 2 organisms stay together for life
- can reproduce outside of the relationship but don’t raise young
Male external reproductive organs (2)
1) Scrotum
2) Penis
What are the 3 Internal Organs in males (3)
1) Gonads
2) Accessory Glands
3) Ducts
What are the Testes?
Highly coiled tubules surrounded by connective tissues
Where is sperm formed?
seminiferous tubules
Normal sperm can’t be produce at?
Normal body temperatures of most mammals
Where are testes held?
Outside of abdominal cavity in scrotum which is where temperatures are lower
Where does Sperm pass into?
Epididymis
Takes 3 weeks for sperm to travel the duct
What happens during ejaculation?
1) Sperm is propelled through VAS DEFERENS and ejaculatory duct
2) Exits the penis through the urethra
What is Semen?
Sperm (5%) plus secretions from 3 sets of accessory glands
What do the two seminal vesicles contribute to semen?
Fructose
about 60% of total volume in semen
What does the Prostate gland contribute to semen?
Secretes alkaline directly into urethra through small ducts
What do the Bulbourethral Glands contribute?
Secrete alkaline, a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra
Penis Composure
3 cylinders of spongy erectile tissue
What are the 3 parts of the penis?
1) glans
2) shaft
3) prepuce
What is an Erection?
Erectile tissue fills with blood from arteries
During sexual arousal
What is the Glans?
Thinner skin than shaft
Sensitive to stimulation
What is the Prepuce?
Foreskin
Female external reproductive structures (3)
1) Clitoris
2) two sets of labia
3) hymen
Female Internal reproductive organs (3)
1) Pair of gonads (ovaries)
2) System of ducts (oviducts/fallopian tube, uterus)
3) Chambers (vagina)
What are Ovaries? (2)
1) Female Gonads
2) contain follicles
What are Follicles?
Consist of partially developed egg (oocyte), surrounded by support cell
What is an Oocyte?
Partially developed egg
What is the function of the Oviduct?
leads egg cell from the ovary to the uterus through the oviduct
What do the cilia in the oviduct do?
convey egg to uterus
What is another name for the Uterus?
Womb
What lines the uterus?
Endometrium
many blood vessels
The uterus narrows at the _______, then opens into the vagina
cervix
What is the Vagina? What does it do?
1) Muscular but elastic chamber
2) Repository for sperm and serves as birth canal
What are the parts of the Vulva?
1) Labia majora
2) Labia Minora
3) Hymen
4) Clitoris
What makes up the Clitoris?
Has a head called a glans coved by prepuce
What is the Mammary Gland?
Not part of reproduction system
Small sacs of epithelial tissue secrete milk
What is the term for the production of gametes
Gametogenesis
What is the term for the formation of sperm? What is a major characteristic?
Spermatogenesis
Continuous and prolific
How much sperm is created per day?
75-100 million
each sperm takes 10 weeks to develop
How much sperm is released per ejaculation
40-500 million
What is the term for the development of mature egg? What is a major characteristic?
Oogenesis
Prolonged process
What happens in the development of eggs in a female embryo?
Immature eggs form in female embryo but don’t developed until years later
What does the corpus luteum produce following ovulation? (2)
1) high levels of progesterone
2) moderate levels of estradiol and inhibin
How does spermatogenesis differ from oogenesis (3)
1) 4 products of meiosis develop into sperm, while only 1/4 becomes an egg
2) Spermatogenesis occurs throughout adolescence and adultood
3) Sperm are continuously produced
Mammalian reproduction is controlled by hormones from? (3)
1) Hypothalamus
2) Anterior pituitary
3) Gonads
What does the Hypothalamus secrete?
Gonadotropin-releasing hormone
What does the Anterior pituitary secrete
FSH and LH
What kind of hormones does the Gonad release?
release steroid hormone
What type of hormones are the main sex hormones?
Steroid Hormones
what is the main Androgen hormone?
Testosterone
What are the main Estrogen hormones
Estradiol and Progesterone
Sex hormone function (3)
1) Gamete production
2) Sexual behavior
3) Secondary sex charcteristics
What is the function of FSH in the male reproductive system?
Stimulates sertoli cells to nourish developing sperm
What is the function of LH in the male reproductive system?
causes leydig cells to produce testosterone and androgens to promote spermatogenesis
Testosterone has inhibitory affects on what?
hypothalamus and anterior pituitary
What do Sertoli cells secrete
Secrete the hormone inhibin
What does Inhibin do in the male reproductive system?
Reduces FSH secretion from anterior pituitary
What female reproductive cycle has changes in ovaries?
Ovarian cycle
What female reproductive cycle has changes in the uterus?
Menstrual cycle
What is Menstruation?
When embryo doesn’t implant in endometrium, it sheds
What happens every menstrual cycle regarding endometrium?
Endometrium thickens with blood vessels for embryo implantation
Describe the Ovarian Cycle (follicular cycle) (5)
1) Begins with GnRH gets released by hypothalamus
2) GnRH stimulates the anterior pituitary to secrete FSH and LH
3) FSH stimulates follicle growth with help from LH
4) Follicles start to make estradiol
5) Maturing Follicle enlarges to form a bulge at surface of ovary
Describe the Ovarian Cycle (luteal phase) (2)
1) LH stimulates remaining follicular tissue to form
2) Corpus luteum secretes progesterone and estradiol inhibiting hypothalamus
When does the follicular phase end?
At ovulation
When does the luteal phase start?
After ovulation
