chapter 16 part a

Chapter 16: Reproductive System

Part A: Male System

1.     Gonads- primary sex organs

a.    Primary sex organs

                                          i.    Males = testes

                                        ii.    Females = ovaries

                                       iii.    Produce sex cells  and secrete hormones

                                       iv.    Males = sperm

                                         v.    Females = ova(eggs)..born with ALL egss

2.    Male reproductive system overview

a.    Testes (2)

b.    Duct system-transport sperm

                                          i.    Epididymis (2)

                                        ii.    Ductus deferens = vas deferens (2)

                                       iii.    Urethra (1)

c.    Accessory organs

                                          i.    Seminal vesicles (2)

                                        ii.    Prostate (1)

                                       iii.    Bulbourethral glands (2)

d.    External genitalia

                                          i.    Penis

                                        ii.    Scrotum

3.    Specialized structures

a.    Testes

                                          i.    Coverings

1.     Tunica albuginea-capsule that surrounds each testis

2.    Septa (singular = septum)- extensions of the capsule; divide testis into lobules

                                        ii.    Internal structure

1.     Lobules contain seminiferous tubules: tightly coiled structures, function as sperm-forming factories

2.    Sperm travels through the rete testis to the epididymis

3.    Interstitial cells in the seminiferous tubules produce androgens (testosterone)

a.    Castration- removal of testes

b.    Duct system

                                          i.    Epididymis

1.     Comma shaped, tightly coiled tube

2.    Functions to  mature and store sperm cells ( at least 20 days)

                                        ii.    Expels sperm with the contraction of muscles in walls to the vas deferens

                                       iii.    Vas deferens

1.     Carries sperm from the epididymis to the ejaculatory duct

2.    Passes through the inguinal canal and over the bladder

3.    Moves sperm by peristalsis

4.    Spermatic cord- ductus deferens, blood vessels, and nerves in a connective tissue sheath

5.    Ends in the ejaculatory duct which unites with the urethra

6.    Ejaculation- smooth muscle in the walls of the vas create peristaltic waves to squeeze sperm forward

7.    Vasectomy- cutting off the ductus deferens at the level of the testes to prevent transportation of sperm

                                       iv.    Urethra

1.     Extends from the base of the urinary bladder to the tip of the penis

2.    Carries both urine and sperm

3.    Sperm enters from the ejaculatory duct

c.    Semen

                                          i.    Mixture of sperm and accessory gland secretions

                                        ii.    Advantages of accessory gland secretions:

1.     Fructose provides energy for sperm cells

2.    Alkalinity of semen helps neutralize the acidic environment of vagina

3.    Semen inhibits bacteria

4.    Elements of semen enhance sperm motility

d.    Accessory organs

                                          i.    Seminal vesicle

1.     Located at the base of the bladder

2.    Produces thick, yellowish secretion (60% of semen)

3.    Contains: fructose(sugar), vitamin C, other substances that nourish and activate sperm

                                        ii.    Prostate

1.     Encircles the upper part of the urethra

2.    Secretes milky fluid that: helps to activate sperm,  enters the urethra through several small ducts

3.    Enlarged prostate constricts flow through urethra

                                       iii.    Bulbourethral gland

1.     Pea-sized gland inferior to the prostate

2.    Produces thick, clear mucus that:

a.    Cleanses the urethra of acidic urine

b.    Serves as a lubricant during sexual intercourse

c.    Secreted into the penile urethra

e.    External genitalia

                                          i.    Scrotum

1.     Divided sac of skin outside the abdomen

2.    Maintains testes at 3^oC (5^oF)- lower than normal body temperature to protect sperm viability

                                        ii.    Penis

1.     Delivers sperm into the female reproductive tract

2.    Regions of the penis:

a.    Shaft- with erectile tissue

b.    Glans penis (enlarged tip)- sensitivity

c.    Prepuce = foreskin: folded cuff of skin around proximal end, often removed by circumcision

3.    Internal

a.    Three areas of spongy tissue

b.    Erections occur

4.    Spermatogenesis

a.    Overview

                                          i.    Production of

                                        ii.    Begins at

                                       iii.    Occurs in

b.    Spermatogonia = stem cells

                                          i.    Follicle-stimulating hormone (FSH) modifies cell division

1.     One cell produced

2.    The other cell produced

                                        ii.    Primary spermatocytes

1.     One primary spermatocyte à

2.    Spermatids

c.    Human life cycle

                                          i.    Union of

1.     N + N =

d.    Spermiogenesis

                                          i.    Late spermatids develop distinct regions:

                                        ii.    Sperm cells result

                                       iii.    Entire spermatogenesis process

e.    Sperm cell anatomy

                                          i.    The only

                                        ii.    Three parts

1.     Head

a.    Contains

b.    Acrosome

c.    Breaks down and releases

2.    Midpiece

3.    Tail

f.    Testosterone production

                                          i.    The most important

                                        ii.    Produced in

                                       iii.    Luteinizing hormone (LH)

1.     This causes

                                       iv.    Functions of testosterone

1.     Stimulates

2.    Underlies

3.    Causes

a.    Deepening

b.    Increased

c.    Enlargement

d.    Thickening