Ch 26 AA - The Reproductive System Flashcards
gametes
specialized cells for sexual reproduction
sperm
gametes in males
ova (eggs)
gametes in females
fertilization
combination of genetic information contained within gametes
zygote
formed when sperm and egg fuse
gestation
development of fetus
parturition
birth of baby
male and female reproductive structures are ___ ___.
homologous structures
homologous structures
share a common origin during development; ex: male testes & female ovaries, male penis & female clitoris
primary sex organs (gonads)
testes (males) & ovaries (female)
sex hormones (steroid hormones)
testosterone (males) & estrogens and progesterone (females)
accessory reproductive organs
ducts, glands, and external genitalia
HPG Axis interacting hormones
GnRH, FSH, LH, testosterone, and inhibin
Hypothalamic-Pituitary-Gonadal (HPG) Axis
production of gametes and sex hormones is regulated by sequence of hormonal events involving hypothalamus, anterior pituitary glands, and testes
Gonadotropin-releasing hormone (GnRH)
released from hypothalamus reaches anterior pituitary cells via hypophyseal portal system
Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)
gonadotropins released from anterior pituitary
exert negative feedback on hypothalamus and anterior pituitary
sex hormones
exerts negative feedback on FSH release from anterior pituitary
inhibin
Before puberty
low levels of circulating levels of steroidal sex hormones are enough to suppress secretion of GnRH by hypothalamus
As puberty approaches
hypothalamus becomes less sensitive to inhibition by sex hormones; hypothalamus releases GnRH in pulselike manner
Activation of the HPG Axis at Puberty
(1) anterior pituitary releases FSH and LH in response to increased GnRH levels (2) FSH and LH stimulate gonads to release more sex hormones from gonads (3) Threshold for inhibition of GnRH continues to rise resulting in more and more release of sex hormones (4) Sex hormones are released until adult pattern of hormone interaction is achieved
sister chromatids
cell’s DNA is replicated during interphase
homologous pairs of chromosomes
one member of each pair is from father and other is from mother; look alike and carry same genes that code for the same traits
nonsister chromatids
within homologous pairs, chromatids of one chromosome are nonsister chromatids to other chromosome in pair
crossing over
nonsister chromatids exchange DNA with each other; increases genetic variability
human diploid number
46; 23 pairs of homologous chromosomes
reduction division of meiosis
during meiosis I, homologous pairs separate from each other, reducing number of chromosomes from 2n to n
equational division of meiosis
during meiosis II, sister chromatids separate and each daughter gets equal share of chromosomes
