A&P Quiz 10 (Ch 28 pt 2)

Male Accessory Glands

exocrine glands that secrete products into the ducts of the male reproductive tract

3 Accessory Glands of Male Reproductive System

seminal vesicles

prostate gland

bulbourethral glands

Seminal Vesicles

accessory gland of male reproductive system, sac-shaped glands, located next to the ampullae of the ducta deferentia, 5 cm long, tapers into a short excretory duct that joins the ampulla of the ductus deferens to form the ejaculatory duct, covered by fibrous connective tissue capsule containing smooth muscle cells

Prostate Gland

resembles a walnut, 4 cm long and 2 cm wide, located dorsal to the pubic symphysis at the base of the urinary bladder, surrounds the prostatic urethra and two ejaculatory ducts

Layers of Prostate Gland

consists of glandular and muscular tissue, covered by a fibrous connective tissue capsule containing distinct smooth muscle cells and many fibrous partitions that radiate into the prostate gland

Cells of Prostate Gland

muscular partitions are covered by columnar epithelial cells that secrete prostatic fluid

15-30 small prostatic ducts empty secretions into the prostatic urethra

Bulbourethral (Cowper) Gland

pair of small glands located near the membranous urethra, compound mucus gland, small ducts from each gland unite to form a single duct that empties into the spongy urethra and the base of the penis

Changes in Bulbourethral Gland Over Lifetime

young males: each gland is the size of a pea

decrease in size with age until they are almost impossible to detect in older males

Semen

composed of sperm cells and secretions from accessory glands

Percentages of Semen

60% of fluid is produced by the seminal vesicles

30% of fluid is produced by the prostate gland

5% of fluid is produced by the testes

5% of fluid is produced by the bulbourethral glands

Testes Contribution to Semen

produce sperm cells, secrete small amount of fluid to allow sperm cells to move through reproductive tract that also contains metabolic by products produced by the sperm cells

Sperm Cells

major components of testicular secretions

Bulbourethral Glands & Urethral Mucous Glands Contribution to Semen

produce alkaline mucous secretion just before ejaculation

Functions of Alkaline Mucous in Semen

lubricate the urethra for sperm movement

neutralize the acidic fluids in the spongy urethra

provide small amount of lubrication during intercourse

reduce vaginal acidity

Seminal Vesicles Contribution to Semen

produce thick mucus secretions that function in nourishment of sperm cells, coagulation of semen, and movement of sperm

3 Functions of Mucus Secreted by Seminal Vesicles

nourishment of sperm cells

coagulation of semen

movement of sperm

Nourishment of Sperm Cells

function of mucus secretion from seminal vesicles, fructose, citric acid, and other nutrients

Coagulation of Semen

function of mucus secretion from seminal vesicles, fibrinogen that is involved in a weak coagulation reaction immediately after ejaculation

Movement of Sperm

function of mucus secretion from seminal vesicles, prostaglandins stimulate uterine contractions to help move sperm through the female reproductive tract

Prostate Gland Contributions to Semen

produces thin milky alkaline secretion, fibrinolysin causes the mass of semen to dissolve to release sperm cells into the reproductive system

3 Functions of Prostate Gland Contributions to Semen

helps neutralize acidic urethral pH (with secretions from seminal vesicles, bulbourethral glands, and urethral mucous glands)

help neutralize acidic secretions of testes and vagina (with secretions from seminal vesicles)

important for transient coagulation of semen due to containing clotting factors that activate fibrinogen

Semen Sperm Count

normal sperm count ranges from 75-400 million sperm per milliliter of semen, normal ejaculation consists of 2-5 mL of semen, semen with highest sperm count is expelled first

Sperm After Ejaculation

sperm cells become motile after ejaculation (alkaline pH, nutrients, and removal of inhibitory substances from sperm cell surface increases motility), enzymes in acrosomal cap help digest a path through mucoid fluids of the female reproductive tract and through materials surrounding the oocyte

Control of Male Reproduction

under both hormonal and nervous control

5 Hormone Responses in Male Reproduction

development of reproductive structures

maintenance of their functional capacities

development of secondary sexual characteristics

control of sperm cell formation

influence sexual behavior

2 Neural Controls of Male Reproduction

sexual behavior

control the sex act

4 Male Reproductive Hormones

gonadotropin releasing hormone

luteinizing hormone

follicle-stimulating hormone

testosterone

(testes produce small amts of estrogen and progesterone)

GnRH in Males

stimulates large quantities of secretion of LH and FSH only when GnRH is produced in a series of pulses, secreted from hypothalamus

LH in Males

stimulates synthesis and secretion of testosterone, secreted from anterior pituitary

FSH in Males

supports spermatogenesis, secreted from anterior pituitary

Testosterone in Males

major male hormone secreted by the testes, supports spermatogenesis, stimulates development and maintenance of reproductive organs, causes development of secondary sexual characteristics

inhibits gnhr, lh, and fsh secretion through negative feedback

Regulation of Male Reproductive Hormone Secretion Involves

hypothalamus

pituitary gland

testes

Androgen

stimulates development of male reproductive structures and male secondary sexual characteristics

2 Conversions of Testosterone

some target cells (penis, scrotum) convert testosterone to dihydrotestosterone

other target cells (brain) convert testosterone to estrogen

Human Chorionic Gonadotropin (hCG)

gonadotropin-like hormone secreted by the placenta that stimulates the secretion and synthesis of testosterone by fetal testes

Puberty in Males Immediately After Birth

no stimulation is present and testes of newborn baby atrophy slightly and secrete only small amounts of testosterone

Males Before Puberty

gnhr release from hypothalamus is inhibited by small amounts of testosterone and other androgens

Puberty

age at which individuals become capable of sexual reproduction

Male Puberty

hypothalamus becomes less sensitive to inhibitory effect of androgens and gnhr secretion increases

gnhr increase lh and fsh secretion from anterior pituitary

fsh promotes sperm production

lh causes interstitial cells to secrete large amounts of testosterone

testosterone has negative feedback effect on gnrh but cannot completely suppress it after puberty

Androgen Production

produced by interstitial cells of testes, includes testosterone, small amounts of androgens are also produced by adrenal cortex and possibly the sustentacular cells

3 Effects of Testosterone

causes enlargement and differentiation of male genitals and reproductive system

necessary for sperm cell formation

affects development of secondary sexual characteristics

1-4 Male Secondary Sex Characteristics

growth of thicker, coarser, pigmented hair in pubic area extending up the linea alba, legs, chest, axillary region, face, back

coarser texture of the skin

darker skin color

increases secretion of sebaceous glands (face)

5-8 Male Secondary Sex Characteristics

hypertrophy of the larynx and reduction of tension on vocal folds

stimulates metabolism

increases erythropoietin production (increases rbc count)

minor mineralocorticoid-like effect causing na+ to be retained and increase body fluid volume

9-11 Male Secondary Sex Characteristics

promotes protein synthesis in most tissue- increasing skeletal muscle mass

growth of bone is stimulated as testosterone is converted to estrogen causing increased ca+2 deposition

sex hormones also stimulate ossification of the epiphyseal plate to stop growth

Testosterone in Male Sexual Behavior

require to initiate and maintain, enters cells in the hypothalamus and surrounding brain regions influencing their function resulting in sexual behavior, may depend on conversion of testosterone to other steroids (estrogen)

Testosterone Levels

stay consistent from puberty to age 40

slowly drop to about 20% of that amount by age 80

causes slow decline in sex drive and fertility

Male Sex Act

complete series of reflexes that result in erection of penis, secretion of mucus into the urethra, emission, ejaculation, orgasm, and resolution

Emission

discharge of all secretions from ducta deferentia into the urethra

Ejaculation

forceful expulsion of semen from urethra caused by contraction of the urethra, skeletal muscles in the pelvic floor, and muscles at the base of the penis

Orgasm

climactic sensation associated with ejaculation as a result of pleasurable sensation during the male sex act

Resolution

follows ejaculation and is characterized by flaccid penis, overall feeling of satisfaction, and inability to achieve erection and second ejaculation for a period of time

Sensory AP and Integration of Male Sex Act

initiated by a variety of sensor stimuli

sensory input is integrated in the sacral region of the spinal cord

input travels to the cerebrum for conscious sexual sensations

input from the cerebrum can reinforce the sacral reflexes but are not required for culmination of the male sex act

Male Sex Act with Spinal Cord Injury

male sex act can be performed by males with spinal cord injuries superior to the sacral region

Sensor Stimuli of Male Sex Act

rhythmic mechanical stimulation of the penis (glans penis) are extremely important for initiation of erection and ejaculation

stimulation of the surrounding tissue (scrotum, anal, perineal, and pubic regions)

engorgement of the prostate and seminal vesicles

mild irritation of the urethra (infection)

psychological stimuli (sight, sound, odor, thoughts) can also inhibit male sex act

Erection

first major component of male sec act, penis becomes enlarged and rigid, ap travels from the spinal cord via the pudenal nerve to the arteries of the erectile tissue, release of ach and nitric oxide cause smooth muscle to relax and blood vessels to dilate, other arteries constrict to shunt blood to the erectile tissue, blood filling the erectile tissue compresses the veins and partially occludes them, input comes from parasympathetic centers (s2-s4) or sympathetic centers (t2-l1) but parasympathetic input is normally more important

Parasympathetic AP in Male Sex Act

also cause mucous glands in the penile urethra and the bulbourethral glands to secrete mucus

Emission Steps

accumulation of sperm cells and secretion of the accessory gland in the urethra, sympathetic centers (T12-L1) are stimulated as the level of sexual tension increases, sympathetic AP cause peristaltic contractions of the reproductive ducts and stimulate seminal vesicles and prostate gland secretion, causes accumulation of semen in the prostatic urethra, produces sensory AP that pass via the pudendal nerves to the spinal cord, integration of sensory AP causes both sympathetic and somatic motor output

Ejaculation Steps

sympathetic AP cause internal urethral sphincter to constrict preventing mixing of semen and urine, somatic motor AP cause contraction of skeletal muscle of the urogenital diaphragm to contract, results in rhythmic contraction that forces semen out of the urethra

Female Reproductive System Consists of

ovaries

uterine tubes

uterus

vagina

external genital organs

mammary glands

Female Internal Reproductive Organs

in the pelvic cavity between the urinary bladder and rectum, uterus and vagina at the midline with ovaries on either side, held in place by a group of ligaments (broad ligament)

Broad Ligament

extension of peritoneum that spreads out on both sides of the uterus and attaches to the ovaries and uterine tubes

Ovaries

female gonads, small organs (2-3.5 cm long, 1-1.5 cm wide)

Mesovarium

peritoneal fold attached to each ovary on the posterior surface of the broad ligament

Suspensory Ligament

extends from mesovarium to the body wall

ovarian arteries, veins, and nerves travel with the suspensory ligament and enter the ovary through the mesovarium

Ovarian Ligament

attaches the ovary to the superior margin of the uterus

Ovarian (Germinal) Epithelium

visceral peritoneum covering ovary, composed of simple cuboidal epithelium

Tunica Albuginea

capsule of dense fibrous connective tissue directly below the ovarian epithelium

2 Regions of Ovary

cortex

medulla

Ovarian Cortex

dense outer portion, ovarian follicles containing oocytes distributed throughout the stroma

Ovarian Medulla

looser inner portion, blood vessels, lymphatic vessels, and nerves from mesovarium enter the medulla

Stroma

connective tissue of the ovary

Oogenesis

production of gametes in females, begins before female is born, by the 4th month of development the ovaries have 5 million oogonia (cells from which oocytes develop), by birth many oogonia degenerate and the remaining ones have differentiated into cells that have begin meiosis, oogonia can form after birth from stem cells but for how long is unclear

Oogonia in Oogenesis

increase in number by mitosis during development, before birth most have differentiated into primary oocytes

Primary Oocytes in Oogenesis

diploid cells, begin meiosis i but stop at birth during prophase i

Oogenesis Continuation at Puberty

primary oocytes reenters and completes meiosis i just before ovulation, cytoplasm is not split evenly between two haploid cells, larger becomes secondary oocyte wile smaller becomes second polar body that can either degenerate or divide to produce second polar bodies that degenerate

Ovulation

release of the secondary oocyte from the ovary, secondary oocyte begins meiosis ii but stops in metaphase ii unless fertilization occurs

When does fertilization begin?

fertilization begins when sperm cells penetrates the cytoplasm of the secondary oocyte, secondary oocyte completes meiosis ii and divides unevenly, larger cell is ovum and smaller cell is a second polar body that degenerates

Oogenesis Diagram

Fertilization

23 chromosomes from the sperm cell nucleus join with 23 chromosomes from the oocytes to forma zygote, zygote has 23 pairs of (46) chromosomes and divided by mitosis to increase number of cells, 7 days after ovulation the mass of cells implants in the uterine wall, develops for 9 months to form a new individual

Follicle Development

ovarian follicles in the ovarian cortex, follicles contain developing primary oocytes, follicles develop as primary oocytes progress through meiosis i

Ovarian Cycle

reoccurring events that take place in the ovaries of sexually mature nonpregnant females, hormonally regulated

Primordial Follicle in Follicle Development

houses the primary oocytes at birth

Granulosa Cells

single layer of flat cells that surround the primary oocyte in the primordial follicle

Primary Oocytes in Follicle Development

2 million present at birth, decreases to 300,000-400,000 at beginning of puberty, about 400 primary oocyte complete development to secondary oocyte

Follicular Development at Puberty

some primordial follicles become primary follicles, oocyte enlarges, granulosa cells thicken and become cuboidal in shape and can increase in number of layers, formation of zona pellucida

Zona Pellucida

layer of clear material that is deposited around the oocyte during puberty when primordial follicles become primary follicles

Secondary Follicle in Follicular Development

about every 28 days hormonal changes stimulate primary follicles to continue to develop into secondary follicle, secondary follicle continues to enlarge to become a mature (graafian) follicle, oocyte is pushed to one side and lies in a mass of granulosa cells called the cumulus cells (cumulus oophorus)

Vesicles in Secondary Follicle

fluid filled spaces form among the granulosa cells when primary follicle develops into secondary follicle

Theca

capsule that forms around the follicle during development from primary to secondary, two layers

2 Layers of Theca

theca interna

theca externa

Theca Interna

layer of theca that surrounds the granulosa cells and synthesize ovarian hormones

Theca Externa

layer of theca that is primarily connective tissues and merges with the stroma of the ovary

Antrum

single fluid filled chamber created by the fusion of vesicles when secondary follicle develops into mature follicle

Follicular Development Diagram

Mature Follicle in Follicular Development

forms a lump on the surface of the ovary, only one mature follicle undergoes ovulation and the rest degenerate (atresia)

ruptures during ovulation to release blood, follicular fluid, and oocyte surrounded by cumulus cells (corona radiata) into the peritoneal cavity

Corpus Luteum

endocrine structure produced by remains of follicle, convoluted appearance as a result of collapse, enlarges and remains active through the first trimester of pregnancy if it occurs (corpus luteum of pregnancy)

Luteal Cells

granulosa cells and theca interna that enlarge and secrete progesterone and smaller amounts of estrogen

Follicular Development if Pregnancy Does Not Occur

corpus luteum remains functional for 10-12 days and then begins to degenerate

decreasing progesterone and estrogen secretions

corpus albicans develops, shrinks, and eventually disappears (month to years)

Corpus Albicans

whitish structure that is produced as the connective tissue cells of the corpus luteum enlarge and become clear