exam 3 reproductive Flashcards
What are the 2 types of reproduction?
asexual & sexual
What is asexual reproduction?
1 cell divides producing 2 identical offspring/daughter cells; they are identical to each other & the “parent” cell
What is mitosis?
the process in which asexual reproduction occurs; in multicellular organisms, this results in any growth/repair in the body
What is sexual reproduction?
2 cells (sperm + oocyte/egg) combine which involves a process called meiosis
What is chromatin?
the threadlike form in which DNA is typically found inside of cells; it is wrapped around specific proteins called histone proteins
What are chromosomes?
they are formed prior to cell division when the chromatin condenses, expands, & replicates
What are chromatids?
the left & right sides of the X-shaped chromosomes; they are identical
What is a centromere?
a sticky part in the center of the chromosome that holds the 2 chromatids together
What does diploid mean?
this term refers to chromosomes being present in pairs; in humans, there are 23 pairs (46 total)
How does mitosis occur?
the centromere dissolves & the chromatids are separated so that each daughter cell gets 1 copy of DNA
How does meiosis occur?
it occurs through 2 stages called meiosis I & meiosis II; only for cells that develop into sperm or egg
What happens in meiosis I?
it separates chromosome pairs to result in 2 haploid cells that have 1/2 the original number of chromosomes
What happens in meiosis II?
chromatids separate as the centromeres dissolve; the resulting cells (which develop into sperm & egg) have 1/2 the number of chromosomes as the parent cell
What is the advantage of meiosis?
the offspring that is formed from the fusion of sperm & egg is diploid which provides genetic variety & keeps chromosomal number constant for each generation
What are the male reproductive structures?
testes, epididymis, vas deferens, glands, & penis
What are the testes?
a pair of 2 inch long oval organs where spermatogenesis occurs (controlled hormonally)
Where do the testes develop in a male fetus?
the abdominopelvic cavity; beginning at week 12 of development, they descend as a retractable strand of tissue called gubernaculum shortens, pulling them through the inferior body wall
What is the inguinal canal?
a body wall opening located on each side of the midline that the testes pass through; it has blood vessels & nerves that pass from torso to legs
Why must the testes descend?
it is critical for sperm to develop at temperatures lower than internal body temperature
What are the layers of the testes from deep to superficial?
tunica albugenia, germinal epithelium, dartos muscle, & scrotum
What is the scrotum?
sack of loose skin; most superficial layer of the testes
What is the dartos muscle?
it lines the scrotum that raises & lowers testes for temperature control
What is the germinal epithelium?
thin serous membrane covering
What is the tunica albugenia?
white, tough fibrous connective tissue covering; deepest
What are lobules?
triangular regions inside the testes formed from the tunica albugenia folding inward; approximately 200 per testis; have walls between them called septa
What are seminiferous tubules?
each lobule is filled with 1-3; tiny coiled tubes where sperm is produced; approximately 0.5 miles of these tubes per testis
What is the rete testis?
a maze-like group of tubes formed from all of the seminiferous tubules merging at the edge of the testis
How do the sperm exit the testis?
through straight tubes called the efferent ducts & enter the epididymis
What is the epididymis?
a tear-drop shaped, 20-23 foot long coiled tube located on superior & posterior edge of each testis; this organ is the site of sperm maturation
What are the 3 regions of the epididymis?
head, body, & tail
When are sperm mature enough to fertilize an egg?
only the sperm exiting the tail region of the epididymis
What is the vas deferens?
18 inch long tube that connects to the tail of the epididymis; it travels ⇧ from scrotum (& testis) ⤏ inguinal canal ⤏ body cavity & turns medially, crosses the superior edge of bladder ⇩ posterior side of bladder ⤏ base of bladder
What are the 3 layers of the vas deferens from deep to superficial?
mucosa, muscularis, & serosa
What is the mucosa layer of the vas deferens?
deepest; made of ciliated epithelium which aids in moving sperm
What is the muscularis layer of the vas deferens?
smooth muscle for peristalsis
What is the serosa layer of the vas deferens?
superficial covering
What is the cremaster muscle?
covers nerves & blood vessels that wrap the vas deferens; aids dartos muscle in positioning the testes for spermatogenesis & temperature control
What is the testicular artery & vein?
the blood vessel that wraps around the vas deferens
What are the genital, testicular, & ilioinguinal nerves?
the nerves that wrap the vas deferens
What is the spermatic cord?
the cremaster muscle, and the nerves & blood vessels that all cover the vas deferens
What are the 3 types of glands in the male reproductive structures?
seminal vesicles, prostate, & bulbourethral glands
What are the seminal vesicles?
a pair of honeycomb shaped glands located on the posterior inferior surface of the bladder
What do seminal vesicles secrete?
carbohydrates that the sperm’s mitochondria use for ATP generation
What is the prostate?
approximately 30 gland units wrapped by a fibrous capsule; donut shaped encircling the urethra
What is the purpose of the prostate’s secretions?
it enhances sperm motility to make them move straighter and faster
What are bulbourethral glands?
a pair of pea-sized glands embedded in the inferior body wall to the left & right of the urethra
What do the bulbourethral glands secrete?
mucous that coats the urethra to protect sperm from urine residue & raises vaginal pH
What is the penis?
has both urinary & reproductive function; made of the corpus spongiosum & corpora cavernosa which are compartmentalized by connective tissue & muscle
What is the corpus spongiosum?
spongy tissue that surrounds urethra & forms the distal end of the penis called the glans penis
What is the corpora cavernosa?
2 cylinders of erectile tissue that surround a central cavernosal artery; they have irregular-shaped open caverns that fill with blood in an erection
When does spermatogenesis start?
at puberty in the seminiferous tubules
What are spermatogonia?
diploid cells that line each seminiferous tubule
What are Sertoli nurse cells?
found between the spermatogonia of the seminiferous tubules
What are interstitial cells of Leydig?
found between the adjacent seminiferous tubules to fill in the gaps
What is GnRH?
gonadotropin releasing hormone; it is released by the hypothalamus at puberty
Where does GnRH travel?
to the anterior part of the pituitary gland causing it to release 2 hormones at the same time which are FSH & LH
What is FSH?
follicle stimulating hormone; travels to Sertoli nurse cells causing them to release a hormone called ABP (androgen binding protein)
What is LH?
luteinizing hormone; travels to interstitial cells of Leydig causing them to release testosterone
What does testosterone do?
grows/maintains sex organs, increases protein synthesis (growth spurt), & causes secondary sex characteristics (body/facial hair & growth of thyroid cartilage to deepen the voice)
What triggers spermatogenesis?
the combination of testosterone & ABP
What does the spermatogonium divide into & through what process?
it divides into primary spermatocyte & spermatogonium through mitosis
What does the primary spermatocyte divide into & through what process?
2 secondary spermatocytes (which are both haploid) through meiosis I
What do the 2 secondary spermatocytes divide into & through what process?
4 spermatids through meiosis II
What is spermiogenesis?
a process by which excess cytoplasm is enzymatically removed by Sertoli nurse cells to transform spermatids into mature sperm
How many sperm are there per mL of semen?
40-300 million
What is the sperm’s flagellum?
the tail; used for swimming (8 inches per hour)
What is the sperm’s midpiece?
contains a spiral arrangement of mitochondria for ATP generation
What is the sperm’s head?
haploid; contains DNA
What is the sperm’s acrosome?
a “cap” containing species-specific enzymes that erode the outer coating of an egg
What are gonads?
unisex term for the organs that produce sperm or egg (testes/ovaries)
What are gametes?
unisex term for sperm or egg
What are accessory structures?
found in male & female to transport or support the development of gametes
Why do both males & females have similar hormones?
to control the development of gametes
