A&P II Chapter 27

What cell are involved in Mitosis

Somatic Cells

What cell are involved in Meiosis

Germ Cells

Mitosis end-product

Two diploid daughter cells

Meiosis end-product

4 haploid daughter cells called gametes

Epididymis

Sperm matures and is stored here until ejaculation. It also absorbs excess testicular fluid and provides nutrients to sperm.

Pampiniform venous plexus

It helps maintain the cooler temperature in the testes by absorbing heat from the testicular arteries, which is needed for sperm production.

Seminal vesicles

Produces viscous, alkaline seminal fluid, which makes up a large portion of semen.

Seminiferous tubules

The sites of sperm production.

Sustentocytes

Provide nutrients and signals to dividing sperm cells. They also secrete testicular fluid into the tubule lumen. Moves spermatocytes and spermatids along the lumen. Acts as a supporting cell and plays a role in sperm formation.

When does Spermatogenesis begin

Begins at puberty around 14 years old.

when does Oogenesis begin

Begins during the fetal period.

where does Spermatogenesis occur

Seminiferous tubules of testis.

where does Oogenesis occur

Ovaries.

What three main events in spermatogenesis

Mitosis of spermatogonia, Meiosis, and Spermiogenesis.

What is the main event in Mitosis of spermatogonia

(stem cell) forms two spermatocytes 

What is the main event of meiosis of spermatogonia

Spermatocytes form secondary spermatocytes, which form spermatids 

What is the main event in Spermiogenesis of spermatogonia

Spermatids become sperm 

Final product of spermatogenesis

4 viable haploid sperm.

Final product of oogenesis

One viable haploid ovum and 2 or 3 haploid polar bodies.

Error rate in spermatogenesis

3-4%.

Error rate in oogenesis

20%.

Ovarian cycle phases

Follicular , Ovulation occurs midcycle between phases, Luteal

What is the length of luteal phase

14-28 days

What is the length of follicular phase

1-14 days

Uterine cycle phases

Menstrual phase, Proliferative (preovulatory) phase, and Secretory (postovulatory) phase

What is the length of Secretory (postovulatory) phase

5-28 days

What is the length of Proliferative (preovulatory) phase

5-14 days

What is the length of menstrual phase

0-4 days

Main event in ovarian follicular phase

Vesicular follicle growth.

Main event in ovarian luteal phase

Corpus luteum activity.

Main event in uterine menstrual phase

Stratum functionalis layer of the endometrium detaches from the uterine wall and is shed out through the vagina.

Main event in uterine proliferative phase

Rising estrogen level prompts endometrium to generate a new stratum functionalis layer.

Main event in uterine secretory phase

Endometrium prepares for the embryo to implant.

Reproductive Structures for Ovulation

Ovary and follicle.

Reproductive Structures for Fertilization

Uterine (fallopian) tubes.

What is Ovulation

It the release of an oocyte from the ovary; it occurs around day 14 of the ovarian cycle

Where does ovulation occur

ovaries

Where does fertilization occur

uterine (fallopian) tubes 

What is fertilization

It is the fusion of sperm and oocyte; it occurs within 24 hours of ovulation

Estrogen effects on the body

Promotes oogenesis and follicle growth, exerts anabolic effects on the female reproductive tract, supports the growth spurt at puberty, induces secondary sex characteristics like growth of breasts, increased deposit of subcutaneous fat (hip, and breasts), and widening and lightening of pelvis, has metabolic effects like maintaining low total cholesterol and high HDL levels, and facilitates calcium intake.

Testosterone effects on the body

Synthesized from cholesterol, transformed at some target cells, converted to dihydrotestosterone (DHT) in prostate and estradiol in some brain neurons, prompts spermatogenesis and targets all accessory organs, has multiple anabolic effects throughout body, deficiency leads to atrophy of accessory organs, semen volume declines, and erection/ejaculation are impaired.

Secondary Sex Characteristics of Estrogen

Induces growth of breasts, increased deposit of subcutaneous fat (hip, and breasts), and widening and lightening of pelvis.

Secondary Sex Characteristics of Testosterone

Appearance of pubic, axillary, and facial hair, enhanced growth of hair on chest or other areas, larynx enlargements cause deepening of voice, skin thickens and becomes oily, bones grow and increase in density, skeletal muscles increase in size and mass, boosts basal metabolic rate, basis of sex drive (libido) in males.

What are the Hypothalamic-pituitary-gonadal (HPG) axis hormones and associated glands

Gonadotropin-releasing hormone (GnRH), Follicle-stimulating hormone (FSH) and luteinizing hormone (LH), sex hormones, and Inhibin

Gonadotropin-releasing hormone (GnRH)

released from the hypothalamus, which travels down to the anterior pituitary.

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Releases Gonadotropins from the anterior pituitary due to GnRH.

FSH Function

Indirectly stimulates spermatogenesis by causing sustentocytes to release ABP which keeps local testosterone high.

LH Function

Stimulates interstitial endocrine cells to secrete testosterone, which is essential for spermatogenesis.

Inhibin

Released from both male and female gonads due to FH (negative feedback loop).

Sex hormones

released from both male and female gonads and acts on target tissue in the body. Acts as a negative feedback to the hypothalamus and anterior pituitary gland.

STI

Also called sexually transmitted disease (STDs) or venereal disease (VD's); the US has the highest rates of infection among developed countries; latex condoms prevent the spread, most important cause of reproductive disorders.

HPV

Most common STI in the US (over 50% of adults are infected during lifetime); 80% of cases of cervical cancer are linked to some strains of HPV; it can cause some penile, anal, and oropharyngeal cancers; vaccination can guard against most common cancer-causing strains; recommended for boys and girls before becoming sexually active.