male reproductive Flashcards

1
Q

Primary sex organs and accessory reproductive organs

A

Primary sex organs (gonads) - testes and ovaries

  • Produce gametes (sex cells ) – sperm & ova
  • Secrete steroid sex hormones
  • Androgens (males)
  • Estrogens and progesterone (females)

Accessory reproductive organs - ducts, glands, and external genitalia

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2
Q

role of sex hormones

A
  • Development and function of reproductive organs
  • Sexual behavior and drives
  • Growth and development of many other organs and tissues
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3
Q

Testes

A

w/in scrotum
make sperm
sperm goes thru epididymis –> ductus deferens –> ejaculatory duct –> urethra

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4
Q

male accessory glands

A

seminal glands
prostate
bulbo-urethral

empty secretions into ducts during ejaculation

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5
Q

Scrotum

A

sac of skin and superficial fascia
-hangs outside abdominopelvic cavity

Contains paired testes

  • 3 C colder than core body temp
  • lower temp necessary for sperm production

Temp kept constant by:

  1. dartos muscle = smooth muscle which wrinkles scrotal skin and pulls scrotum close to body
  2. cremaster muscles = bands of skeletal muscle that elevate testes
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6
Q

Testes tunics and lobules

A

Each surrounded by two tunics

  1. Tunica vaginalis – outer layer derived from peritoneum
  2. Tunica albuginea – inner layer; fibrous capsule

Septa divide testis into ~250 lobules, each containing 1–4 seminiferous tubules - site of sperm production—about ½ mile of seminiferous tubules

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7
Q

Testicular Torsion

A

MEDICAL EMERGENCY

Must be corrected within 2 hours to save the testes

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8
Q

path of sperm inside the testes

A

sminiferous tubules –> straight tubule –> rete testis –> efferent ductules –> epididymis

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9
Q

Seminiferous tubules: interstitial cells

A

Interstitial endocrine cells (Leydig cells) in soft tissue surrounding seminiferous tubules

Produce androgens (e.g. testosterone) and secrete it into interstitial fluid

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10
Q

Blood supply to the testes

A

Testicular arteries arise from abdominal aorta

Testicular veins arise from pampiniform venous plexus surrounding each testicular artery

  • Cooler; absorb heat from testicular arteries
  • Keep testes cool

Spermatic cord encloses nerve fibers, blood vessels, and lymphatics that supply testes

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11
Q

external genitalia

A

scrotum and penis

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12
Q

Penis parts

A

root and shaft that ends in glans penis

prepuce/foreskin = cuff of loose skin covering glans

Crura = proximal ends of corpora cavernosa surrounded by ischiocavernosus muscle; anchors penis to pubic arch

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13
Q

Circumcision

A

Surgical removal of foreskin

60% newborn boys in US circumcised

15% in other parts of world

Some claim medically unnecessary

Studies show

  • 60% reduction in HIV risk
  • Reduced risk for other reproductive system infections like HPV
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14
Q

Penis: Internally

A

Spongy urethra and three cylindrical bodies of erectile tissue (spongy network of CT and smooth muscle with vascular spaces)

Corpus spongiosum surrounds urethra and expands to form glans and bulb

Corpora cavernosa = paired dorsal erectile bodies

Erection = erectile tissue fills with blood causing penis to enlarge and become rigid

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15
Q

Epididymis
head, body, tail
duct
sperm flow

A

Head - contains efferent ductules; superior aspect of testis; body and tail on posterolateral area of testis

Duct of the epididymis ~ 6 m in length
-Microvilli (stereocilia) absorb testicular fluid and pass nutrients to stored sperm

Nonmotile sperm enter, pass slowly through (~ 20 days), become motile; can be stored several months

During ejaculation epididymis contracts, expelling sperm into ductus deferens

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16
Q

Ductus Deferens and ejaculatory duct

A

Ductus deferens (vas deferens) ~ 45 cm

Passes through inguinal canal to pelvic cavity

Expands to form ampulla; joins duct of seminal vesicle to form ejaculatory duct

Smooth muscle in walls propels sperm from epididymis to urethra

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17
Q

Vasectomy

A

cutting and ligating ductus deferens; nearly 100% effective form of birth control. Must give time for any remaining sperm in the ducts to die.

18
Q

urethra

A

Conveys both urine and semen (at different times)

Has three regions

  1. Prostatic urethra – surrounded by prostate
  2. Intermediate part of the urethra (membranous urethra) – in urogenital diaphragm
  3. Spongy urethra – runs through penis; opens at external urethral orifice
19
Q

Seminal Glands

A

On posterior bladder surface; smooth muscle contracts during ejaculation

Produces viscous alkaline seminal fluid

  • Fructose, citric acid, coagulating enzyme (vesiculase), and prostaglandins
  • Yellow pigment fluoresces with UV light
  • 70% volume of semen

Duct of seminal gland joins ductus deferens to form ejaculatory duct

20
Q

Prostate

A

Encircles urethra inferior to bladder; size of peach pit; smooth muscle contracts during ejaculation

Secretes milky, slightly acid fluid

  • Contains citrate, enzymes, and prostate-specific antigen (PSA)
  • Role in sperm activation
  • Enters prostatic urethra during ejaculation

1/3 semen volume

21
Q

Bulbo-urethral glands (cowper’s glands)

A

pea-sized glands inferior to prostate

make thick, clear mucus during sexual arousal

  • lubricate glans penis
  • neutralize traces of acidic urine in urethra
22
Q

Semen contents

A

Milky-white mixture of sperm and accessory gland secretions

2–5 ml semen ejaculated, contains 20–150 million sperm/ml

Contains fructose for ATP production; protects and activates sperm; facilitates sperm movement

Alkaline  neutralizes acidity of male urethra and female vagina  enhanced motility

23
Q

Semen functions

A

Prostaglandins decrease viscosity of mucus in cervix; stimulate reverse peristalsis in uterus

Contains ATP for energy

Suppresses female immune response

Antibacterial action

Clotting factors coagulate semen initially to prevent draining out; then liquefied by fibrinolysin  sperm begin journey

24
Q

Erection: what happens

A

Arterioles normally constricted

Sexual excitement causes CNS activation of parasympathetic neurons

nitric oxide (NO) release  local vascular smooth muscle relaxation

arterioles dilate  corpora cavernosa expands, retards venous drainage

engorgement of erectile tissues with blood

enlargement and stiffening of penis

25
Q

Initiation of erection

and protection of penis during

A

Initiated by sexual stimuli
-Touch; mechanical stimulation of penis; erotic sights, sounds, and smells

Can be induced or inhibited by emotions or higher mental activity

Longitudinal and circular collagen fibers around penis prevent kinking/buckling of erect penis

Corpus spongiosum keeps urethra open

26
Q

Ejaculation

A

Propulsion of semen from male duct system

Sympathetic spinal reflex

  • Bladder sphincter muscle constricts, preventing expulsion of urine
  • Ducts and accessory glands contract and empty their contents
  • Bulbospongiosus muscles undergo rapid series of contractions  expulsion of semen at ~ 500 cm/s (close to 11 mph)

Ejaculatory event – orgasm

27
Q

HTG axis

A

Hypothalamus: Gonadotropin releasing hormone (GnRH)

  • Simulates release of hormones from anterior pituitary that regulate function of testes
  • Pulsatile release to produce stable FSH + LH levels

Anterior pituitary:
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)

Testes:
Testosterone (T)
Inhibin
-both have negative feedback on hypothalamus and ant. pituit.

28
Q

Actions of FSH and LH

A

FSH causes sustenocytes (sustenacular cells/ Sertoli cells) to release androgen binding protein (ABP) –> binds testosterone and keeps it near spermatogenic cells for spermatogenesis

LH prods interstitial endocrine cells (Leydig) to secrete testosterone for spermatogenesis

29
Q

Testosterone and Inhibin

  • when is inhibin released?
A

Testosterone = sex organ maturation, development/maintenance secondary sex characteristics, libido

Rising testosterone levels –> feedback inhibition on hypothalamus

Inhibin released when sperm count is high –> inhibits GnRH and FSH

30
Q

Development of HPG axis

A

takes 3 years to achieve balance, then testosterone and sperm porduction is fairly stable throughout life

Without GnRH and gonadotropins, testes atrophy; sperm and testosterone production cease

31
Q

Male secondary sex characteristics

A

Features induced in NONREPRODUCTIVE organs by male sex hormones

  • pubic, axillary, and facial heair
  • chest hair
  • deep voice
  • skin thickens and becomes oily
  • skeletal muscles increase in size and mass
  • bones grow and increase in density
  • boosts BMR
  • basis of sex drive in males
32
Q

Testosterone in embryo

A

masculinizes embryonic brain

continues to exert effect well into adulthood

adrenal glands produce androgens in small amounts– insufficient to maintain normal testosterone-mediated functions

33
Q

spermatogenesis

A

sperm (spermatozoa) production in seminiferous tubules

Spermatogenic cells give rise to sperm

  • mitosis of spermatogonia (stem cells) forms 2 spermatocytes
  • meiosis: spermatocytes –> secondary spermatocytes –> spermatids
  • spermiogenesis = spermatids become sperm
34
Q

functions of meiosis

A

halve the number of chromosomes

introduce genetic diversity

35
Q

Mitosis of spermatogonia

A

Spermatogenesis begins at puberty

Spermatogonia = stem cells in contact with epithelial basal lamina
-each mitotic division = one type A daughter cell and one type B daughter cell

Type A cells maintain germ cell line at basal lamina

Type B cells move toward lumen and develop into primary spermatocytes

36
Q

Meiosis: spermatocytes to spermatids

A

Meiosis I
-primary spermatocytes (2n) –> two secondary spermatocytes (n)

Meiosis II

  • each secondary spermatocyte (n) –> two spermatids (n)
  • Spermatid = small, nonmotile cells close to lumen of tubule
37
Q

Spermatids to sperm

A

Spermatids
-correct chromosome number (n), but nonmotie

Spermiogenesis
-spermatids elongate; lose excess cytoplasm; form a tail –> spermatozoon (sperm)

38
Q

Sperm major regions

A

Head = genetic region; nucleus and helmet-like acrosome containing hydrolytic enzymes that enable sperm to penetrate egg

Midpiece = metabolic region; mitochondria –> ATP to move tail

Tail = locomotor region; flagellum

39
Q

Role of sustentocytes (sertoli cells)

A

Extend through wall of tubule and surround developing cells

Provide nutrients and signals to dividing cells

Move cells along to lumen

Secrete testicular fluid into lumen for sperm transport

Phagocytize faulty germ cells and excess cytoplasm

Produce chemical mediators to regulate spermatogenesis

40
Q

two compartments of sustentocytes

A

Tight junctions divide tubule into two compartments:

Basal compartment: spermatogonia and early primary spermatocytes

Adluminal compartment: meiotically active cells and tubule lumen

41
Q

Blood testis barrier

A

tight junction bt sustentocytes form this barrier

  • prevents sperm antigens from escaping into blood –> activation of immune system
  • important: sperm not formed until puberty - absent during immune system development, would not be recognized as self
42
Q

How long does spermatogenesis take?

What pushes immotile sperm into epididymis?

A

takes 64-72 days if conditions are hospitible

Pressure of testicular fluid pushes the sperm –> THEN they get their motility and fertilizing power