14.1 Male Reproductive System Flashcards
What are gametes?
haploid sex cells that become united during fertilization
What are the male gonads?
paired testes
What do testes do?
produce sperm and sex hormones
What is the epididymis?
tightly coiled ducts lying outside the testes where sperm produced by the testes mature
Where does the sperm go after it leaves the epididymis?
they enter the vas deferens, where they may also be stored for a time
What does each vas deferens pass into?
the abdominal cavity, where it curves around the urinary bladder and empties into an ejaculatory duct, which connects to the urethra
What is seminal fluid?
nutrient-rich fluid in which the sperm leaves the penis at the time of ejaculation
What is semen?
combination of sperm and seminal fluid
What does swimming sperm require and what is the source?
energy, and semen contains the sugar fructose which serves as the energy source
What adds secretions to semen?
three glands
- seminal vesicle
- prostate gland
- Cowper’s gland
Where are the paired seminal vesicles?
lie at the base of the bladder, and each has a duct that joins with a vas deferens
What is the function of the testes?
produce sperm and sex hormones
What is the function of the epididymis?
ducts where sperm mature and are stored
What is the function of the vas deferens?
conducts and stores sperm
What is the function of the seminal vesicles?
contribute nutrients and fluid to semen
What is the function of the prostate gland?
contributes basic fluid to semen
What is the function of the urethra?
conducts sperm
What is the function of the Cowper’s gland?
contribute viscours fluid to semen
What is the function of the penis?
organ of sexual intercourse
What is the prostate gland?
single, donut-shaped gland that surrounds the upper portion of the urethra just below the urinary bladder
What does the prostate gland produce?
a secretion containing HCO3- (bicarbonate), sperm are more viable in a basic solution
What is another name for Cowper’s gland?
bulbourethral gland
What are Cowper’s glands?
pea-sized organs that lie underneath the prostate on either side of the urethra
What do Cowper’s glands secrete?
a lubricating mucus-rich fluid that is milk in appearance and viscous in texture
What does the component of semen secreted by the Cowper’s glands do?
helps lubricate penis and facilitates penetration during sexual intercourse
What is a prostaglandins?
component of semen, local hormones that cause the uterus to contract
What is prostaglandin secreted by?
seminal vesicles
What is the penis?
male organ of sexual intercourse that has a long shaft and an enlarged tip called the glans penis
What is the glans penis covered by at birth?
a layer of skin called the foreskin
What is circumcision?
surgical removal of the foreskin, sometimes performed for cultural reasons or perceived health benefits
What extends through the shaft of the penis?
spongy, erectile tissue containing distensible blood spaces
What happens when a man is sexually excited?
- arteries in the penis relax and widen
- increased blood flow causes the penis to enlarge and become erect
- veins that normally carry blood away from the penis get compressed and maintains an erection
What happens when sexual stimulation intensifies?
- sperm enter the urethra from the vasa deferentia and the accessory glands contribute secretions to the semen
What happens once semen is in the urethra?
rhythmic muscle contractions cause it to be ejaculated from the penis in spurts
What happens during ejaculation?
a sphincter normally closes off the urinary bladder so that no urine enters the urethra and no semen enters the bladder
What is a refractory period?
stimulation does not bring about an erection
What is the scrotum?
saclike structure outside the abdominal cavity of a male that houses the testes
Where do testes begin their development?
inside the abdominal cavity but descend into the scrotal sacs during the last two months of fetal development
What happens if the testes fail to descend properly?
remain in abdomen, male infertility may result because the internal temperature of the body is too high to produce viable sperm
What does the scrotum do?
helps regulate the temperature of the testes by holding them closer or farther away from the body
What decreases sperm production?
any activity that increases testicular temperature, such as taking hot baths or using a laptop computer
What do lobules contain?
1-3 tightly coiled seminiferous tubules
What are seminiferous tubules?
long, coiled structures contained within chambers of the testis where sperm are produced, combined length of 250 m
What is spermatogenesis?
production of sperm
What does a microscopic cross section of a seminiferous tube reveal?
that it is packed with cells undergoing spermatogenesis
Where do newly found spermatogonia go?
move away from the outer wall and become PRIMARY SPERMATOCYTES that undergo meiosis I to produce SECONDARY SPERMATOCYTES with 23 chromosomes
What do secondary spermatocytes undergo?
meiosis II to produce 4 spermatids that are also haploid
What do spermatids do?
differentiate into sperm
What are Sertoli cells (sustentacular cells)?
support, nourish, and regulate the spermatogenic cells
What do mature sperm look like?
head, middle piece, tail
What is the function of the mitochondria in the middle piece of sperm?
the site of cellular respiration and the production of ATP for the movement of the tail, which has the structure of a flagellum
What does the head of sperm contain?
a nucleus covered by a cap called the acrosome, which stores enzymes needed to penetrate the egg
What does the nucleus of the sperm contain?
father’s DNA as 23 chromosomes
What are interstitial cells?
male sex hormones (the androgens) are secreted by cells that lie between the seminiferous tubules
What is the most important of the androgens?
testosterone
What does the hypothalamus control?
the glandular secretions of the pituitary gland
What is the pituitary gland?
small gland ~1 cm in diameter, connected to the hypothalamus by a stalklike structure
What are the 2 portions of the pituitary gland?
posterior
anterior
Why does the hypothalamus have ultimate control of the testes’ function?
it secretes a hormone called gonadotropin-releasing hormone (GnRH) that stimulates the anterior pituitary to secrete gonadotropic hormones
What are the 2 gonadotropic hormones?
follicle-stimulating hormones (FSH) and luteinizing hormone (LH) in both males and females
What does FSH promote in males?
production of sperm in the seminiferous tubules, which also release the hormone inhibin
What does inhibin do?
inhibits further FSH synthesis
Whart is LH in males sometimes called?
interstitial cell-stimulating hormone (ICSH) because it controls the production of testosterone by the interstitial cells
What are hormones involved in?
the negative feedback relationship that maintains the fairly constant production of sperm and testosterone
What is testosterone?
main sex hormone in males that is essential for the normal development and functioning of the organs
What else does testosterone do?
brings about and maintains the male secondary sex characteristics that develop at the time of puberty
What are the deeper voices of males due to?
a larger larynx with longer vocal cords, Adam’s apple is more prominent
What is testerone responsible for?
- facial hair, chest hair, back hair
- greater muscular development
What is anabolic steroids?
either testosterone or related steroid hormones for both males and females
What health problems can arise because of steroids?
- involves kidneys, circulatory system, hormonal imbalances
- in males, testes shrink in size, feminization of other male traits occur
Describe the hormonal control of testes.
- GnRH stimulates the anterior pituitary to produce FSH and LH
- FSH stimulates the testes to produce sperm, and LH stimulates the testes to produce testosterone
- testosterone from interstitial cells and inhibin from the seminiferous tubules exert negative feedback control over the hypothalamus and the anterior pituitary, and this ultimately regulates the level of testosterone in the blood
