Reproduction Flashcards
Asexual Reproduction
Involves the formation of individuals whose genes all come from one parents
In stable environments, allows for the per
Sexual reproduction
formation of offspring by the fusion of haploid gametes
Increases genetic variation among offspring
Ovum
Female gamete, usually large and motile
Spermatozooan
Male gamete, usually small and motile
External fertilization
Requires a moist habitat that will protect developing egg from desiccation and heat stress
Internal Fertalization
Requires cooperative behaviour that leads to copulation
Usually results in the production of fewer zygotes than EF
Eggs of birds/reptiles are protected by a calcium and protein shell
Testes
Male gonads
Consist of many seminiferous tubules surrounded by layers of connective tissue
Sperm form in seminiferous tubules
Leydig cells produce androgens
Androgens
Male sex hormones
Responsible for sexual behaviour and general aggressiveness
Leydig Cells
Produce testosterone in the presence of lutenizing hormone (LH)
Epididymis
A highly convoluted tube that connects a testicle to the vas deferens
Sperm becomes motile and gains the ability to fertizile
Vas Deferens
Runs from the scrotum and behind the urinary bladder
Here each vas deferens joins with a duct from the seminal vesicle to form an ejactulatory duct
Ejaculation
propels sperm from the epididymis to the vas deferens
from there the sperm goes up to the ejaculatory duct
duct opens into the urethra
Accessory Sex Glands
Add secretions to semen
Semen
60% is mucus, fructose, a coagulation enzyme, asorbic acid, prostaglandins
Prostate gland
Gland surrounding the neck of bladder in male mammals and releasing prostatic fluid
Fluid is thin and milky
Penis
Composed of three layers of spongey tissue
During sexual arousal erectile tissue fills with blood from the arteries
Resultant pressure seals off the veins that drain the penis
Female internal reproductive organs
A pair of gonads and a system of ducts and chambers
The role of the ducts and chambers is to conduct the gametes and house the embryo and fetus
Ovaries
Female gonads
Each ovary contains follicles
Each ovary is enclosed in a tough protective capsule
Follicles in the ovaries
Consists of one egg surrounded by one or more layers of follicles cells
produce estrogen: primary female sex hormone
women are born with around 400 000 follicles
Corpus Luteum
Hormone secreting structure that develops in an ovary after an ovum has been discharged, but degenerates after a few days if pregnancy hasn’t begun
secretes estrogen and progesterone
Egg path to uterus
Egg is released into the abdominal cavity near the opening of the oviduct
cilia-lined funnel-like opening draws in egg
cilia move egg through to oviduct to uterus
Enometrium
Highly vascularized inner lining of the uterus
Cervix
Neck of uterus that opens into the vagina
Vagina
Thinly walled chamber that forms the birth canal and is a repository for sperm
Vaginal opening
Until ruptured is partially covered by the hymen
Vestible
Where the vaginal and urethra openings are
surrounded by the labia minora
Bartholins Glands
secrete mucus into the vestible
provides lubrication and facilitates intercourse
Spermatogenesis
Production of mature sperm cells from spermatogonia
As spermatogenesis progresses the developing sperm cells move from the wall to the lumen of a seminiferous tubule
Sperm structure
Haploid nucleus
tipped with acrosome
contains enzymes that help the sperm penetrate the egg
Large number of mitochondria provide ATP to flagellum
Oogenesis
Is the production of ova from oogonia
Ovum
Mature female reproductive cell that can divide to give rise to an embryo usually only after fertilization by a male cell
Primary sex characteristics of males
Development of vas deferens and other ducts
Development of external reproductive structures
Sperm production
Secondary sex characteristics of males
Deepening of voice
facial and pubic hair
muscle growth
Menustral cycle
menstrual flow
proliferative phase
secretory phase
Ovarian cycle
Follicular phase
Luteal Phase
Follicular phase
GnRH simulates secretion of small amount of FSH and LH
Growing follicles secrete small amounts of estrogen
Inhibits secretion of FSH and LH
FSH and LH levels remain relatively low
The timing of this phase is coordinated with the proliferative phase of the menustral cycle
Luteal Phase
Follicle tissue remaining in the ovary develops into corpus luteum
Coordinated with secretory phase of menustral cycle
FSH
Follicle stimulating hormone
released by anterior pituitary gland
stimulates the growth of immature ovarian follicles
LH
Lutenizing hormone
secreted by anterior pituitary
triggers ovulation and development of corpus luteum
Female secondary sex characteristics
Deposition of fat in breasts and hips
Increased water retention
Affects calcium metabolism
Stimulates breast development
