1a1 - chapter 27 Male Reproduction Flashcards Preview

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Flashcards in 1a1 - chapter 27 Male Reproduction Deck (146):
1

biparental

essence of sexual reproduction
offspring receive genes from two parents
–offspring not genetically identical to either one

2

gametes

(sex cells) produced by each parent

3

zygote

(fertilized egg) has combination of both parent’s genes

4

one gamete has motility,

sperm (spermatozoon)
•parent producing sperm considered male
•parent with a Y chromosome is male

5

other gamete contains nutrients

egg or (ovum)
parent producing eggs considered female
anyone lacking a Y chromosome is female

6

female is the parent that provides

a sheltered internal environment and prenatal nutrition of the embryo

7

copulatory organ (penis

males have a copulatory organ (penis) for introducing his gametes into the female reproductive tract

8

copulatory organ (vagina)

females have a copulatory organ (vagina) for receiving the sperm

9

male reproductive system

serves to produce sperm and introduce them into the female body

10

female reproductive system

produces eggs, receives sperm, provides for the union of the gametes, harbors the fetus, and nourishes the offspring

11

primary sex organs

(gonads)
•produce gametes (testes or ovaries)

12

secondary sex organs

organs other than the gonads that are necessary for reproduction

13

male

system of ducts, glands, penis deliver sperm cells

14

female

uterine tubes, uterus, and vagina receive sperm and harbor developing fetus

15

external genitalia

located in the perineum
–most are externally visible
–except accessory glands of the female perineum

16

internal genitalia

located mainly in the pelvic cavity
–except tor testes and some associated ducts in the scrotum

17

secondary sex characteristics

features that further distinguish the sexes and play a role in mate attraction
–develop at puberty to attract a mate

18

Androgen-Insensitivity Syndrome

occasionally, a girl shows all the usual changes of puberty, but fails to menstruate

19

sex of child determined by type

of sperm that fertilizes mother’s egg
–X-carrying sperm fertilizes the egg –female
–Y-carrying sperm fertilizes the egg -male

20

initially, a fetus is

sexually undifferentiated as to which sex it will become
•gonads begin to develop at 5 or 6 weeks as gonadal ridges

21

two sets of ducts adjacent to each gonadal ridge

determine sex

mesonephric ducts develop into male reproductive system
paramesonephric ducts (müllerian ducts) develop into female reproductive tract

22

SRY gene

(sex-determining region of Y chromosome)
–in males, codes for a protein, testes-determining factor (TDF), that initiates development of testes
•begin to secrete testosterone 8 to 9 weeks

23

female development occurs in absence of

androgen hormones

24

genital tubercle

becomes the head (glans) of the penis or glans clitoris

25

urogenital folds

pair
encloses urethra of male forming the penis or forms the labia minora

26

labioscrotal folds

pair
becomes either scrotum or labia majora

27

by week 12, either

male or female genitalia are distinctly formed

28

male and female organs that develop from the same embryonic structure are

homologous
–penis is homologous to the clitoris
–scrotum is homologous to the labia majora

29

gubernaculum

a connective tissue cord extends from the gonad to the floor of the pelvic cavity

30

vaginal process

of the peritoneum that extends into the scrotum

31

inguinal canal

pathway of low resistance through the groin created by gubernaculum and vaginal process
•most common site of herniation in boys and men –inguinal hernia

32

cryptorchidism

boys born with undescended testes
–occurs in about 3% of male births

33

descent of the testes begins as early as

6 weeks

34

external genitalia

of the male –scrotum and penis
–occupy the perineum–

35

perineum

diamond-shaped area between the thighs
•bordered by the pubic symphysis, ischial tuberosities, and coccyx

36

scrotum

pouch of skin, muscle, and fibrous connective tissue containing the testes

37

left testicle

usually descends lower than the right so the two are not compressed against each other

38

skin

has sebaceous glands, sparse hair, rich sensory innervation, somewhat darker pigmentation than skin elsewhere

39

internal median septum

divides scrotum into right and left compartments

40

perineal raphae

medial seam located on the scrotum extending anteriorly along ventral side of penis and posteriorly to anus

41

spermatic cord

bundle of fibrous connective tissue containing the ductus deferens, blood and lymphatic vessels, and testicular nerve
–continues through 4 cm inguinal canal into the pelvic cavity

42

external inguinal ring

inferior entrance to the inguinal canal

43

internal inguinal ring

superior exit to the pelvic cavity

44

sperm temperature

must be held at about 35°C

45

scrotum has three mechanisms to regulate the temperature of the testes

cremaster muscle
dartos muscle
pampiniform plexus

46

cremaster muscle

strips of the internal abdominal oblique muscle
•enmesh the spermatic cord
•in cold temperatures, contracts and draws testes upward toward body
•in warm temperatures relaxes suspending testes further from the body

47

dartos muscle

subcutaneous layer of smooth muscle
•contracts when it is cold, wrinkling the scrotum, holding testes against warm body
•reducing surface area of the scrotum and reducing heat loss

48

pampiniform plexus

an extensive network of veins from the testes that surround the testicular artery and spermatic cord

49

countercurrent heat exchanger

without the pampiniform plexus, warm arterial blood would heat the testis and inhibit sperm production
•removes heat from the descending arterial blood
•by the time it reaches the testis, the blood is 1.5°-2.5°cooler

50

testes

(testicles) –combined endocrine and exocrine glands that produce sex hormones and sperm

51

tunica albuginea

white fibrous capsule on testes

52

connective tissue septa divides testes into

250 to 300 wedge-shaped lobules

53

seminiferous tubules

–one to three in each lobule
–each tubule lined with a thick germinal epithelium for sperm generation

54

interstitial (Leydig) cells

between tubules produce testosterone

55

sustentacular (Sertoli)

cells in between germ cells
–protect the germ cells, and promote their development
–germ cells depend on them for nutrients, waste removal, growth factors, and other needs

56

blood-testis barrier

formed by tight junctions between sustentacular cells
–separating sperm from immune system
–prevents antibodies and other large molecules in the blood from getting to germ cells
–germ cells are immunologically different from body cells and would be attacked by immune system

57

rete testis

a network embedded in the capsule on the posterior side of the testis collect sperm from seminiferous tubules
–move with flow of fluid (float) secreted by the sustentacular cells
–sperm do not actively swim while they are in the male reproductive tract

58

testicular artery

supplies each testis
–low BP of testicular artery results in poor O2supply to the testes
–sperm develop very large mitochondria helping them survive hypoxic environment of female reproductive tract

59

blood leaves the testes through the

pampiniform plexus which converge to form the testicular veins
–right testicular vein drain to inferior vena cava
–left one drains into left renal vein

60

testicular nerves

from spinal cord segments T10 and T11
–carrying sensory fibers concerned with pain and motor fibers regulating blood flow

61

spermatic ducts from testis to the urethra

efferent ductules
duct of the epididymis
ductus (vas) deferens
ejaculatory duct

62

efferent ductules

about 12 small ciliated ducts collecting sperm from rete testes and transporting it to epididymis

63

duct of the epididymis

epididymis(head, body and tail)
•site of sperm maturation and storage (fertile for 40 to 60 days)
•contains a single 6 m long coiled duct adhering to posterior of testis
•sperm mature as they travel through the duct
•if not ejaculated, they disintegrate and epididymis reabsorbs them

64

ductus (vas) deferens

•muscular tube 45 cm long passing up from scrotum through inguinal canal to posterior surface of bladder
•duct widens behind the bladder and widens into the terminal ampulla
•duct ends by uniting with the duct of the seminal vesicle
•thick wall of smooth muscle well innervated by sympathetic nerve fibers

65

ejaculatory duct

2 cm duct formed from ductus deferens and seminal vesicle and passing through prostate to empty into urethra

66

Male Urethra

18 cm long male urethra is shared by the reproductive and urinary systems

67

consists of three regions

prostatic, membranous, and spongy (penile) urethra

68

Accessory Glands

there are three sets of glands in the male reproductive system

seminal vesicles
prostate gland
bulbourethral (Cowper) glands

69

seminal vesicles

•pair of glands posterior to bladder
•empties into ejaculatory duct
•forms 60% of semen

70

prostate gland

•surrounds urethra and ejaculatory duct just inferior to the bladder
•30 to 50 compound tubuloacinar glands
•empty through about 20 pores in the prostatic urethra
•thin milky secretion forms 30% of semen

71

bulbourethral (Cowper) glands

•near bulb of penis
•during sexual arousal, they produce a clear slippery fluid that lubricates the head of the penis in preparation for intercourse
•protects the sperm by neutralizing the acidity of residual urinein the urethra

72

benign prostatic hyperplasia (BPH)

noncancerous enlargement of the prostate
–compresses urethra and obstructs flow of urine
–promotes bladder and kidney infections

73

prostate cancer

–second most common cancer in men after lung cancer
–tend to be near the periphery of the gland where they do not obstruct urine flow
–go unnoticed until they cause pain

74

digital rectal exam (DRE)

palpated through rectal wall to check for tumors

75

prostate cancer

diagnosed from

elevated levels of serine protease (PSA)and acid phosphatase in the blood

76

penis

penisserves to deposit semen in the vagina
–half of the penis is an internal root
–half is an externally visible shaft
–external portion 4 in. long when flaccid(nonerect)
•5 –7 inches long when erect

77

skin over shaft

loosely attached allows expansion
•extends over glans as prepuce (foreskin)
•removed by circumcision

78

smegma

waxy secretion produced by the sebaceous glands in the glans and facing surface of the prepuce

79

three cylindrical bodies of erectile tissue

which fill with blood during sexual arousal and account for its enlargement and erection
-single corpus spongiosum
-two corpora cavernosa

80

corpus spongiosum

along ventral side of penis
•encloses spongy (penile) urethra
•distal end enlarges and forms the glans penis
•proximal end ends as a dilated bulb ensheathed by bulbospongiosus muscle

81

corpora cavernosa

two
•diverge like arms of a Y
•each arm called a crusattaches the penis to pubic arch
•covered with ischiocavernosus muscle

82

the three cylinders of erectile tissue are

spongy
–contain many blood sinuses called lacunae
–trabeculae–partitions between lacunae

83

adolescence

the period from the onset of gonadotropin secretion and reproductive development until a person attains full adult height

84

puberty

first few years of adolescence, until the first menstrual period in girls or the first ejaculation of viable sperm in boys

85

onset of puberty

surge of pituitary gonadotropins awakens the reproductive system

86

from puberty through adulthood, reproductive function is regulated by

hormonal links between the hypothalamus, pituitary gland, and the gonads

87

as hypothalamus matures it produces

gonadotropin-releasing hormone (GnRH)

88

GnRH

stimulates anterior pituitary cells (gonadotropes) to secrete:
-follicle stimulating hormone (FSH)
-luteinizing hormone (LH)
-

89

follicle stimulating hormone (FSH)

stimulates sustentacular cells to secrete androgen-binding proteinthat binds testosterone keeping it in the seminiferous tubule lumen to stimulate spermatogenesis and raising sperm count

90

luteinizing hormone (LH)

sometimes called interstitial cell-stimulating hormone (ICSH)
–stimulates interstitial cells to produce testosterone

91

inhibin

inhibin from sustentacular cells suppresses FSH output from the pituitary reducing sperm production without reducing LH and testosterone secretion

92

decline in testosterone secretion with age

–peak secretion at 7 mg/day at age 20
–declines to 1/5 of that by age 80

93

male climacteric (andropause)

rise in FSH and LH secretion after age 50

94

erectile dysfunction (impotence)–

the inability to produce or maintain an erection sufficient for intercourse
–20% of men in 60s to 50% of those in 80s

95

spermatogenesis

process of sperm production in seminiferous tubules

96

involves three principal events:

–remodeling of large germ cells into small, mobile sperm cells with flagella
–reduction of chromosome number by one-half in sperm cells (unites with egg to return to 46)
–shuffling of genes so new combinations exist in the sperm that are different from the parents

97

four sperm cells produced from one germ cell by

meiosis

98

mitosis

a body cell doubles its DNA and then divides to produce two genetically identical daughter cells
–basis for division of the single-cell fertilized egg, growth of an embryo, all postnatal growth, and tissue repair
–consists of four stages: prophase, metaphase, anaphase, and telophase

99

meiosis

meiosis produces four gametes (haploid cells), each with only half the DNA of the diploid body cells
–combining male and female gametes with half the genetic material produces an embryo with the same number of chromosomes as each of the parents
–meiosis is sometimes called reduction division

100

reduction division

meiosis is sometimes called reduction division

101

meiosis has two cell divisions

(following one replication of DNA) with each division having four stages
-meiosis I
-interkinesis
-meiosis II

102

meiosis I

–before this begins, the DNA is doubled….
–prophase I each pair of homologous chromosomes lines up side by side and form tetrad
–crossing-over creates new combinations of genes
–after meiosis I, each cell has 23 chromosomes, but each is double-stranded

103

meiosis II

–more like mitosis
–each of the double-stranded chromosomes divides into two chromatids and resulting four cells are truly haploid with 23 chromosomes

104

primordial germ cells

form in the yolk sac of the embryo
–they colonize the gonadal ridges and become spermatogonia

105

puberty brings on

spermatogenesis

106

spermatogenesis

process

–spermatogonialie along the periphery of the seminiferous tubules and divide by mitosis
–one daughter cell of each division remains in the tubule wall as stem cell -type A spermatogonium
–other daughter cell migrates slightly away from the wall and is on its way to producing sperm –type B spermatogonium

107

type B spermatogonium

enlarges and becomes a primary spermatocyte
•sustentacular cells protect it from the body’s immune system –blood-testis barrier (BTB)
•primary spermatocyte undergoes meiosis I which gives rise to two equal-size, haploid, genetically unique secondary spermatocytes
•each secondary spermatocyte undergoes meiosis II dividing into two spermatids–a total of four for each spermatogonium
•spermiogenesis–four spermatids divide no further, but undergo a transformation in which it differentiates into a spermatozoon

108

Blood-Testis Barrier

•once the primary spermatocyte undergoes meiosis, it becomes genetically different and needs to be protected from thei mmune system
•the primary spermatocyte moves towards the lumen of the seminiferous tubule and a new tight junction between sustentacular cells forms behind it
•now protected by the blood-testis barrier closing behind it

109

spermiogenesis

-changes that transform spermatids into spermatozoa
–discarding excess cytoplasm and growing tails

110

spermatozoon two parts:

head and tail

111

head

head is pear-shaped
•4 to 5 microns long structure containing the nucleus, acrosome and basal body of the tail flagella
•nucleus
•acrosome
•basal body

112

acrosome

enzyme cap over the apical half of the nucleus that contains enzymes that penetrate the egg

113

basal body

indentation in the basal end of the nucleus where flagellum attaches

114

nucleus

contains haploid set of chromosomes

115

tail is divided into 3 regions

midpiece
principal piece

116

midpiece

midpiececontains mitochondria around axoneme of the flagella, produces ATP for flagellar movement

117

principal piece

is axoneme surrounded by sheath of supporting fibers
•constitutes most of tail

118

endpiece

very narrow tip of flagella

119

semen

(seminal fluid) –fluid expelled during orgasm

120

normal sperm count

50-120 million/mL

121

infertility

lower than 20 to 25 million/mL

122

prostate

produces a thin, milky white fluid
•contains calcium, citrate, and phosphate ions
•a clotting enzyme
•protein-hydrolyzing enzyme called serine protease (prostate-specific antigen)

123

seminal vesicles

contribute viscous yellowish fluid
•contains fructose and other carbohydrates, citrate, prostaglandins, and protein called proseminogelin

124

stickiness of semen promotes

fertilization
•clotting enzyme from prostate activates proseminogelin
•converts it to a sticky fibrin-like protein –seminogelin
•entangles the sperm
•sticks to the inner wall of the vagina and cervix

125

two requirements for sperm motility

elevated pH and an energy source
•prostatic fluid buffers vaginal acidity from 3.5 to 7.5
•seminal vesicles provide fructose and other sugars to the mitochondria

126

Male Sexual Response

divided intercourse into four recognizable phases

•excitement
•plateau
•orgasm
•resolution

127

sexual intercourse is also known as

coitus, coition, or copulation

128

internal pudendal (penile) artery

enters the root of the penis and divides in two:
dorsal artery
deep artery

129

dorsal artery

travels under skin on dorsal surface
•supplies blood to skin, fascia, and corpus spongiosum

130

deep artery

travels through the core of the corpus cavernosa
•gives off smaller helicine arteries that penetrate the trabeculae and enter lacunae
•dilation of deep artery fills lacunae causing an erection
•when penis is flaccid, most blood comes from the dorsal artery

131

deep dorsal vein

drains blood from penis

132

innervation of penis

–the glans has an abundance of tactile, pressure, and temperature receptors
–dorsal nerve of penis and internal pudendal nerves lead to integrating center in sacral spinal cord
–both autonomic and somatic motor fibers carry impulses from integrating center to penis

133

sympathetics

sympathetics induce an erection in response to input from the special senses and to sexual thoughts

134

parasympathetics

parasympathetics induce an erection in response to direct stimulation of the penis

135

excitement phase

is characterized by vasocongestion (swelling of the genitals with blood), myotonia (muscle tension), and increases in heart rate, blood pressure, and pulmonary ventilation

136

plateau phase

the variables such as respiratory rate, heart rate, and blood pressure stay increased
–marked increased vasocongestion and myotonia
–lasts for a few seconds or a few minutes before orgasm

137

orgasm or climax–

a short but intense reaction that is usually marked by the discharge of semen
–lasts 3 to 15 seconds
–heart rate, blood pressure, and breathing greatly elevate

138

ejaculation occurs in two stages:

emission
expulsion

139

emission

sympathetic nervous system stimulates peristalsis which propels sperm through ducts as glandular secretions are added

140

expulsion

semen in urethra activates somatic and sympathetic reflexes that stimulate muscular contractions that lead to expulsion
•sympathetic reflex constricts internal urethral sphincter so urine cannot enter the urethra and semen can not enter the bladder

141

resolution phase

body variables return to pre-excitement state
–sympathetic signals constrict internal pudendal artery and reduce blood flow to penis
–penis becomes soft and flaccid (detumescence)
–cardiovascular and respiratory responses return to normal

142

refractory period

period following resolution in which it is usually impossible for a male to attain another erection or orgasm
–may last from 10 minutes to a few hours

143

How Viagra Prolongs Erection

sexual stimulation triggers nitric oxide secretion, which activates cGMP, which increases blood flow into erectile tissue
–this drugs slow down the breakdown of cGMPby phosphodiesterasetype 5 and prolongs the duration of the erection

144

Sexually Transmitted Diseases

STDs have an incubation period in which the pathogen multiplies with no symptoms and a communicable period in which the disease can be transmitted to others
–symptomless carriers do exist

145

bacterial STDs

chlamydia –may cause urethral discharge and testicular pain
–gonorrhea –pain and pus discharge –may result in sterility from pelvic inflammatory disease
–syphilis –hard lesions (chancres) at site of infection

146

viral STDs

–genital herpes –most common STD in US
•blisters and pain
–genital warts –warts on perineal region, cervix, anus
–hepatitis B and C –inflammatory liver disease