BIO TEST #10 - REPRODUCTIVE SYSTEM (FINAL CHAPTER) :O

organisms that carry out sexual reproduction must produce what?

gametes, haploid sex cells that are united during fertilization

the reproductive system is different in males and females. what does the gametes look like in male reproductive system

the sperm are gametes that are produced in paired testes (male gonads)

what are the testes

paired structures that produce sperm and sex hormones

what are the epididymides

ducts outside the testes where sperm mature and are stored

when sperm leave an epididymis, where do they enter?

vas deferens

what is the vas deferens

stores sperm and empties into an ejaculatory duct which connects to the urethra

at the time of ejaculation, what happens

sperm leaves the penis in a nutrient rich fluid called seminal fluid

what is semen

the combination of sperm and seminal fluid

how does semen help sperm

swimming sperm require energy and semen contains the sugar fructose which serves as an energy source

what three glands add secretions to semen

seminal vesicles, prostate gland, and cowper’s gland

describe the seminal vesicles location

the pair lie at the base of the bladder and each has a duct that joins with a vas deferens

what does the seminal vesicles add to semen

they contribute fructose for swimming sperm

describe the structure of a prostate gland

single donut shaped gland that surrounds the upper portion of the urethra just below the bladder

what does the prostate gland contribute

contributes a basic solution containing bicarbonate since sperm are more viable in a basic solution

describe the structure of cowper’s gland (bulbourethral glands)

pea sized organs that lie underneath the prostate on either side of the urethra

what do the cowper’s glands contribute

a mucus-rich fluid that is milky in appearance and viscous in texture that helps lubricate the penis

what does semen contain that causes the uterus to contract

local hormones called prostaglandins secreted by the seminal vesicles

what is the male organ of sexual intercourse

penis

the penis has a long shaft and an enlarged tip called the what?

glans penis which is covered by a layer called the foreskin at birth

what is circumcision

surgical removal of the foreskin

what extends through the shaft of the penis

spongy erectile tissues 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, and the veins that normally carry blood away from the penis get compressed

what happens when sexual stimulation intensifies

sperm enter the urethra from the vasa differentia and the accessory glands contribute secretions to the semen

what causes semen to be ejaculated from the penis

rhythmic muscle contractions that are part of a male orgasm (climax of sexual stimulation)

what happens during ejaculation

a sphincter closes off the bladder so that no urine enters the urethra and no semen enters the bladder

what happens after ejaculation

a refractory period occurs where sexual stimulation does not cause an erection and can last from minutes to hours

how much sperm are expelled in 2-6mL of semen during ejaculation

more than 400million

where do the testes lie

outside the abdominal cavity within the saclike scrotum

explain how the testes develop

begin their development inside the abdominal cavity but descend into the scrotal sacs during the last two months of fetal development

how can male infertility result

if the testes fail to descend properly and remain in the abdomen where the internal temperature of the body is too high to produce viable sperm

what is the function of the scrotum

helps regulate testicular temperature by holding the testes closer or farther away from the body

a longitudinal section of a testis would show what?

compartments called lobules, each of which contains tightly coiled seminiferous tubules

what would a microscopic cross section of a seminiferous tubule reveal

it is packed with cells undergoing spermatogenesis, the production of sperm

describe what happens to newly formed spermatogonia

they 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 four spermatids that are haploid and differentiate into sperm

what are sertoli cells (sustentacular cells)

they support, nourish, and regulate the spermatogenic cells

describe the structure of mature sperm of spermatozoa

they have a head, middle piece, and tail

what lies in the middle piece of mature sperm

mitochondria which is the site of cellular respiration and the production of ATP for the movement of the tail (flagellum)

what does the head of a mature 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?

the father’s DNA as 23 chromosomes

what are intersitial cells

they lie between the seminiferous tubules and secrete male sex hormones (androgens)

what does the hypothalamus control

secretions of the pituitary gland

what are the two portions of the pituitary gland

posterior pituitary and anterior pituitary

why does the hypothalamus have ultimate control of the testes’ function?

by secreting gonadotropin-releasing hormone (GnRH) which stimulates the anterior pituitary to secrete the gonadotropic hormones

what are the two types of gonadotropic hormones? (in both males and females)

follicle stimulating hormone (FSH) and luteinizing hormone (LH)

in males, what does the follicle stimulating hormone do

promotes the production of sperm in the seminiferous tubules which release the hormone inhibin

what does inhibin do

inhibits FSH synthesis

why is LH also called interstitial-cell-stimulating hormone?

it controls the production of testosterone by the interstitial cells

what is testosterone?

main sex hormone in males that is essential for normal development and functioning of male reproductive structures

what is the function of testosterone

maintains male secondary sex characteristics that develop at puberty like body hair, deeper voices, and greater muscular development

why are mens voices deeper

they have a larger larynx with longer vocal cords

in the female reproductive system, what is the gamete?

the egg or oocyte

how is the oocyte made?

produced through oogenesis in the female gonads called the ovaries where they alternate in producing one oocyte per month

describe the location of the paired ovaries

lie in the shallow depressions on each side of the upper pelvic cavity

what is ovulation

process by which an oocyte bursts from an ovary and usually enters an oviduct

what are oviducts

also called fallopian tubes or uterine tubes which extend from the uterus to the ovaries

what do oviducts have since they are not attached to the ovaries

they have finger like projections called fimbriae that sweep over the ovaries

what happens when an oocyte bursts from an ovary during ovulation?

fimbriae and beating cilia in the ovaries sweep the oocyte into an oviduct

what happens when an oocyte reaches an oviduct

it is propelled by cilia and muscle contractions toward the uterus and only lives 6-24 hours unless fertilization occurs

what occurs in the oviduct?

fertilization and formation of a zygote occurs

if fertilization occurs, what happens

the developing embryo implants itself in the uterine lining several days after fertilization

when would an ectopic pregnancy occur?

when the embryo implants outside the uterus like in the oviduct

describe the uterus (womb)

thick walled organ lined with endometrium which helps form the placenta and houses the developing fetus

the oviducts join the uterus at its upper end, what lies at its lower end?

the cervix which contains an opening to the uterus and connects with the vagina

in a non pregnant female, the functional layer of the endometrium varies in thickness according to what?

a monthly cycle of events called the uterine cycle

what does the vagina contain

mucosal lining that lies in folds and can extend

what are the functions of the vagina

serves as the birth canal, exit for menstrual flow, and facilitates sexual intercourse

what is the collective name for the external genital organs

vulva

what makes up the vulva

labia majora, labia minora, mons pubis, clitoris, and hymen

what is the labia majora

large folds of skin covered with hair that extend backward from the mons pubis

what is the mons pubis

fatty area underlying pubic hair

what is the labia minora

two small folds of skin inside the labia majora

what is the clitoris

organ of sexual arousal that has an external portion called the glans clitoris

what do both men and women have in terms of sexual stimulation

the penis/clitoris contains a shaft of erectile tissue that becomes engorged with blood

what is the hymen

ring of tissue that partially blocks the vagina

describe what happens upon sexual stimulation in females in terms of blood

labia minora, vaginal wall, and clitoris become engorged with blood

describe what happens upon sexual stimulation in females in terms of the labia majora

they enlarge, redden, and spread away from vaginal opening

what does the vagina do during sexual stimulation

it expands and elongates

describe what happens upon sexual stimulation in females not in terms of the vagina

breasts swell and nipples become erect

describe lubrication for the vagina

provided by blood vessels in the vaginal wall that release fluid and by mucus-secreting glands beneath the labia minora

orgasms occur at the height of the sexual response. what exactly happens?

blood pressure + pulse rise, breathing quickens, and the walls of the vagina, uterus, and uterine tubes contract rhythmically

what is different between men and women after an orgasm occurs

females have little or no refractory period between orgasms and multiple orgasms can occur during a single experience