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Phys II Unit III > 1 Male Reproduction > Flashcards

1 Male Reproduction Flashcards

1
Q

The primary reproductive organs where gametes are produced in males

A

Testes

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2
Q

What are the accessory structures of the male reproductive system?

A 
Penis
Scrotum
Vas deferens (ductus deferens)
Epididymis
Accessory glands
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3
Q

What are the male secondary sexual characteristics?

A

Facial and body hair
Larger muscle mass
Masculine jaw
Body height

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4
Q

Testes have what 2 compartments and what 3 cell types

A

Compartments: Seminiferous tubules, Connective tissue

Cell types: Germ cells, Sertoli cells, Leydig cells

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5
Q

The seminiferous tumbles make up _____% of the testes, while the connective tissue makes up ______%.

A

ST = 80% vs CT = 20%

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6
Q

Which compartment of the testes is the site of spermatogenesis?

A

Seminiferous tubules

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7
Q

What do Sertoli cells produce?

A

Antimüllerian hormone
Androgen binding protein
Inhibin
Seminiferous tubule fluid

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8
Q

What do Leydig cells secrete?

A

Testosterone

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9
Q

Spermatogenesis is a ___________-mediated process that occurs along the length of the seminiferous tubules

A

Testosterone

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10
Q

The process by which undifferentiated diploid germ cells (___________) become haploid __________.

A

Spermatogonia —> spermatozoa (sperm)

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11
Q

How long does spermatogenesis take?

A

~74 days

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12
Q

What are the three stages of spermatogenesis?

A
  1. Mitosis (proliferation —> 4 diploid primary spermatocytes)
  2. Meiosis (2 divisions —> 16 single strand DNA spermatids)
  3. Spermiogenesis (packaging)
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13
Q

What occurs during the Mitosis stage of spermatogenesis?

A

Proliferation of diploid germ cells

Two divisions to create 4 diploid primary spermatocytes

Each has double strands of DNA

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14
Q

What happens during the Meiosis stage of spermatogenesis

A

Undifferentiated diploid germ cells are converted to haploid spermatocytes

Two divisions to create 16 spermatids

Each spermatids has single strand of one chromosome

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15
Q

During embryonic development, germ line cells help form the gonad and become ….

A

Spermatogonia

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16
Q

At puberty, spermatogonia undergo mitosis divisions and greatly expand their numbers. Some spermatogonia enter the first meiosis division, at which point they become…

A

Primary spermatocytes

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17
Q

Each primary spermatocyte becomes ________________.

A

Two secondary spermatocytes

Each secondary spermatocyte ends the second round of meiosis, producing two spermatids

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18
Q

Developing sperm cells do not complete cytokinesis (full cytoplasmic division) during meiosis, therefore the four daughter cells remain connected, forming a __________.

A

Syncytium

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19
Q

_________ ensures the haploid cells that contain either an X or a Y chromosome have access to all the gene products available in a complete diploid genome

A

Syncytium

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20
Q

Further maturation of the spermatids create the _________.

A

Spermatozoa

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21
Q

What establishes the blood-testes barrier?

A

Tight junctions between Sertoli cells

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22
Q

What is the point of the blood-testes barrier?

A

Developing sperm move between tight junctions between the Sertoli cells to the lumen, preventing immune cells from accessing genetically variant spermatozoa

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23
Q

Spermatocytes and Sertoli cells form __________ and _________.

A

Tight junctions and Gap junctions

Gap junctions permit transfer of nutrients

Final release of spermatids requires breakdown of these connections

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24
Q

Early spermatids remain joined by ___________, allowing XY sperm to transport necessary gene products to XX sperm.

A

Cytoplasmic bridges

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25
What are the functions of Sertoli cells?
Protect sperm and provide nourishment to developing sperm Absorb excess cytoplasm and wastes from developing sperm Secrete seminiferous tubule fluid to aid in flushing sperm to the epididymus Produce androgen binding protein to sequester Testosterone Release Inhibin, anti-Müllerian factor
26
Sertoli cells secrete __________ to aid in flushing sperm to epididymus
Seminiferous tubule fluid
27
Sertoli cells produce __________ to sequester testosterone
Androgen binding protein Allows for 100x more T in testes than in circulation
28
Sertoli cells are stimulated by _______ and ________ but release _________
Stimulated by T and FSH Release Inhibin (negatively feedback to reduce FSH)
29
During development, Sertoli cells secrete _________.
Anti-Müllerian Factor
30
Process by which spermatids mature into spermatozoa
Spermiogenesis
31
What happens to the head of spermatids as they mature into spermatozoa?
Head elongates, most of the cytoplasm is lost Nucleus remodels —> chromatin condensation Lysosomes aggregate to form ACROSOME
32
What happens to the midpiece of spermatids as they mature into spermatozoa?
Mitochondria sequester to midpiece —> powering spearman’s
33
What happens to the tail of spermatids as they mature into spermatozoa?
Microtubules create the flagellum tail
34
The process by which mature sperm are extruded from the Sertoli cells into the lumen of the seminiferous tubules
Spermiation From here they pass through the Rete testes for final processing and storage
35
What propels spermatozoa into the vas deferens?
Contraction of myoepithelial cells
36
Maturation area located close to the upper portion of each testicle
Epididymus
37
What do the sperm in the epididymus look like?
Not yet capable of movement or fertilization - require further maturation Concentrated Sperm are transferred to here under pressure and by smooth muscle contractions
38
What are the three steps in spermatogenesis?
1. Spermatogenesis: spermatogonia —> spermatozoa 2. Spermiogenesis: packaging and maturation of spermatozoa 3. Spermiation: release of spermatozoa from Sertoli cells into the lumen of seminiferous tubules
39
Temporal organization of the spermatogonia cycle for continuous production
Spermatogonia wave Rate is constant and not accelerated by hormones Germ cells that fail to differentiate will degenerate and be reabsorbed
40
Full cycle of spermatogenesis takes ________ and luminal migration to ejaculatory ducts takes ________.
74 days 14 days
41
How many spermatogonia begin the spermatogenesis process each day
~2 million 😳
42
How many mature sperm are produced daily?
~128 million
43
_______ seminiferous tubules per testis allow for _______m of tubule length with different waves of spermatogenesis occurring simultaneously
~500 tubules ~300m
44
The average sperm count in the western world today is ...
Between 20-40 million per ml of ejaculate
45
When do testes descend into the scrotum?
At ~7th month of gestation
46
Why does spermatogenesis require cooler temperature (1-2˚C below body temp)?
Prevents lysosomal destruction
47
Testes are kept cooler than body temp by...
Air around scrotum Contraction/relaxation of muscles (rugae) Venous blood flow (countercurrent)
48
What is the most widespread environmental factor producing low sperm counts?
Interference with ability of the scrotum to cool the testes Tight clothing, hot tubs, sitting too long (ie truck drivers)
49
What is the medical term for undescended testes?
Cryptorchidism Affected individuals are unable to produce viable sperm
50
Hormonal control of spermatogenesis is through the pulsatile release of _______.
GnRH - Gonadotropin-releasing hormone Stimulates release of FSH and LH from Anterior Pituitary
51
What is the primary target of FSH in males?
Follicle Stimulating Hormone sensitized Sertoli cells to testosterone Promotes Inhibin and Androgen binding protein (ABP) secretion from Sertoli cells
52
What is the primary target of LH in males?
Luteinizing hormone stimulates cholesterol desmolase within Leydig cells to produce testosterone
53
Testosterone regulates __________ by negative feedback
LH and LSH
54
Inhibin selectively regulates ________.
FSH
55
How does testosterone impact embryonic/fetal development
Masculinization of the reproductive tract and external genitals Promotes descent of testes into scrotum
56
How does testosterone effect sex-specific tissue after birth?
Promotes maturation of reproductive system at puberty Required for spermatogenesis Maintains reproductive tract throughout life
57
What are the reproduction-related effects of testosterone?
Increases sex drive Controls secretion of gonadotropins
58
What are the effects of testosterone on secondary sex characteristics?
Male-pattern hair growth Deepening of voice Promotes muscle growth and male adiposity
59
What are the non-reproductive effects of testosterone?
Increased protein anabolic effect Promotes bone growth at puberty Closes epiphyseal plates (via aromatase conversion to estrogen) May induce aggressive behavior Male-specific brain development (preoptic area, hippocampus, amygdala - via aromatase conversion to estrogen)
60
Testosterone is produced in ...
Leydig cells of the testes
61
The rate limiting step in the biosynthesis of testosterone
Conversion of cholesterol to pregnenolone (via cholesterol desmolase) Regulated by LH
62
Testosterone can be peripherally converted to what two things?
Dihydrotestosterone (DHT) via 5a reductase Estradiol (E2) via aromatase
63
What allows for the concentration of testosterone in the seminiferous tubules?
Binding to androgen-binding protein (ABP) produced by the Sertoli cells
64
How does testosterone circulate within the peripheral circulation?
Bound to sex-hormone binding globulin (SHBG)
65
Which hormone: Testosterone, DHT, Estradiol Beard growth Prostate growth Sebum formation
DHT
66
Which hormone: Testosterone, DHT, Estradiol Development of penis, scrotum, urethra, prostate
DHT
67
Which hormone: Testosterone, DHT, Estradiol Development of epididymis, vas deferens, seminal vesicles
Testosterone
68
Which hormone: Testosterone, DHT, Estradiol Feedback suppression of gonadotropin secretion
All three
69
Which hormone: Testosterone, DHT, Estradiol Imprint male pattern of gonadotropins, sex drive, behavior
All three
70
Which hormone: Testosterone, DHT, Estradiol Deepening of voice
Testosterone
71
Which hormone: Testosterone, DHT, Estradiol Skeletal development
Testosterone, Estradiol
72
Which hormone: Testosterone, DHT, Estradiol Abdominal visceral fat
Testosterone
73
Which hormone: Testosterone, DHT, Estradiol Increasing muscle mass
Testosterone
74
Which hormone: Testosterone, DHT, Estradiol Red blood cells
Testosterone
75
Which hormone: Testosterone, DHT, Estradiol Increased VLDL, LDL and decreased HDL
Testosterone
76
Which hormone: Testosterone, DHT, Estradiol Sperm production
All three
77
Which hormone: Testosterone, DHT, Estradiol Pubertal development of penis and seminal vesicles
Testosterone and DHT
78
Androgen effects of Testosterone
Differentiation of epididymis, vas deferens, and seminal vesicles (inner sex organs) Increased muscle mass Pubertal growth spurt Growth of penis and seminal vesicles during puberty Deepening of voice Negative feedback on anterior pituitary Libido
79
Androgen effects of DHT on target tissues
Differentiation of penis, scrotum, and prostate (outer sex organs) Male hair pattern Male pattern baldness Sebaceous gland activity Growth of prostate ****DHT is twice as potent as testosterone
80
In the prepubertal phase, secretion of LH and FSH is ...
Low, due to hippocampal inhibition of GnRH
81
During puberty, there is _________ secretion of GnRH
Increased secretion —> increased LH and FSH —> increased testosterone and spermatogenesis
82
Decreased production of testosterone and sperm with aging
Senescence
83
What are the symptoms of Androgen Deficiency in the Aging Male (ADAM)?
``` Decreased bone formation Decreased muscle mass Decreased sex drive Decreased body height Decreased hematocrit Decreased facial hair INCREASED CVD risk (incl ED) Changes in mood/energy Changes in appetite ```
84
Endocrine consequence to testosterone replacement therapy
Reductions in LH, FSH through negative feedback Reduced sperm production —> infertility Increase in free estrogens b/c exogenous T will free estrogens from binding proteins (b/c T has a higher affinity) Increased peripheral conversion of T to estrogens
85
Risks of testosterone replacement therapy
``` CVD Visceral obesity Erythrocytosis Fluid retention BPH Prostate cancer Acne Hepatotoxicity Infertility Obstructive sleep apnea Gynecomastia and breast cancer Psychosis/aggression Depressed immunity —> cancer ```
86
_____________ is sufficient to stimulate pubic and axial hair growth in both men and women
DHEA from the adrenal cortex
87
_________ stimulates hair growth in men and is the cause of male pattern hair loss
DHT (male androgenetic alopecia)
88
What happens to castrated males and eunuchoidal patients with androgen-insensitivity syndrome and those with a 5a-reductase deficiency
They don’t go bald, b/c they can’t produce DHT
89
Beard growth is stimulated by...
Synergism between DHT and IGF-1 in those cells
90
Scalp hair growth is attentuated by...
DHT and transforming growth factor ß1 (TGF-ß1)
91
What exactly happens to lead to male pattern baldness?
Hair follicle miniaturization occurs with 5a-reductase conversion of T to DHT
92
Propecia (finasteride) is used for the treatment of...
Androgenetic alopecia or enlarged prostates It’s a 5a-reductase antagonist —> binds IRREVERSIBLY to the enzyme and doesn’t let it convert T to DHT
93
Why shouldn’t women handle propecia?
Could impact fetal development of males due to it being a non-competitive inhibitor of 5a-reductase
94
Side effects of propecia (finasteride)
ED Loss of libido Reduced ejaculate
95
What are the different accessory organs for semen production?
Seminal vesicles Prostate Bulbourethral glands
96
Seminal vesicles produce _____% of the total ejaculate
60%
97
What are the different products of the seminal vesicles?
FRUCTOSE to nourish sperm PROSTAGLANDINS to stimulate male and female reproductive tract CLOTTING FACTORS
98
Prostatic fluid makes up _____% of total ejaculate
20%
99
Which accessory organ secretes alkaline fluid to counter acidic vaginal environment and pH triggers clotting to keep sperm in vagina?
Prostate
100
Bulbourethral gland secretions make up ____% of the ejaculate
10%
101
What is the purpose of the bulbourethral gland?
Secrete mucus for lubrication
102
What are the main components of semen by percentage?
Seminal fluid from seminal vesicles (60%) Prostatic fluid (20%) Bulbourethral fluid (10%) Spermies (10%)
103
Walnut sized structure that surrounds the neck of the bladder and the urethra
Prostate
104
Bacterial infection of the prostate
Prostatitis Can cause problems with urination
105
Enlarged prostate which may restrict oral urination or cause increased frequency of urination
Benign Prostatic Hyperplasia BPH No relationship between BPH and prostate cancer
106
What do we need to know about prostate cancer?
It responds to treatment when detected early No relationship between BPH and prostate cancer
107
How is male erection achieved?
Due to VASOCONGESTION of the penis with blood (NOT due to skeletal muscle contraction)
108
What are the three compartments of the penis important for the male erection?
Two corpus cavernosa One corpus spongiosum Arterioles in these compartments dilate during sexual arousal and constrict in the absence of arousal
109
How does thinking about sex —> erection?
The amygdala, medial preoptic area, paraventricular nucleus of the hypothalamus, and peri aqueductal gray matter coordinately affect penile erections
110
What is the integration site for the central nervous system control of erections?
Medial Preoptica Area (MPOA) Receives sensory input from the amygdala and sends impulses to the paraventricular nuclei and then the periaqueductal gray matter in sacral spinal cord
111
How does the erection reflex work?
1. Higher brain activity (thinking about sex) 2. Mechanical stimulation of the glans —> sensory feedback to the sacral erection generating center (sacral S2-4) 3. Periodic parasympathetic impulses from the sacral erection generating center
112
How to make an erection: Parasympathetic stimulation —> _______ release —> production of _________ —> lowering _______ Mechanical compression of _________ Parasympathetic stimulation of _______ glands
NO release —> production of cGMP —> lowering intracellular Ca2+ Mechanical compression of veins by skeletal muscles at the base of the penis Parasympathetic stimulation of the bulbourethral glands
113
Tonic sympathetic stimulation results in...
Flaccid penis
114
Concurrent sympathetic inhibition and parasympathetic stimulation can create an erection in...
As little as 5 seconds
115
In the flaccid state, blood flow into penile tissue is limited by...
Contraction of helicine arteries and trabecular smooth muscle
116
In the erect state, relaxation of _________ by NO released from nerve terminals allows blood flow into the cavernous spaces to induce penile engorgement
Helicine arteries
117
Compression of __________ reduces venous outflow, sustaining erection
Subtunical venules
118
What are the two phases of ejaculation?
Emission | Expulsion
119
What does the emission phase of ejaculation entail?
SNS impulses from L1 and L2 Semen enter urethra from the contraction of the accessory glands SNS stimulation of smooth muscle and contraction of accessory glands
120
What does the expulsion phase of ejaculation entail?
Filling of the urethra triggers somatic nervous impulses with rhythmic activation of skeletal muscles at the base of the penis
121
What is the volume of ejaculation?
2-6 ml total, after several days of abstinence 100 million sperm/ml
122
What is the pathway for ejaculation?
Vas deferens —> ampulla —> urethra —> out
123
The ________ contracts to prevent retrograde ejaculation into bladder
Internal urethral muscle (sphincter)
124
What happens during the excitement phase and how is it driven?
Flushed skin and increased muscle tone, nipples harden, blood flow to genitals increases, scrotum tightens, some lubricating emissions from the penis Driven by parasympathetic NS
125
What is the plateau phase?
Testicales are withdrawn into the scrotum, conditions of excitement phase intensify, leading to the orgasm stage
126
What is orgasm?
The intense pleasure associated with the culmination of expulsion of semen Involuntary muscle contractions, rhythmic contractions at base of penis result in ejaculation of semen. Heightened emotions, pleasure, HR, perspiration
127
What happens during the resolution phase following orgasm?
Sympathetic vasoconstrictor impulses return body to normal function Blood flow into the penis slows Temporary refractory period of variable duration
128
The failure to achieve an erection despite appropriate stimulation
Erectile dysfunction
129
What are the different pathophysiologies of ED?
``` Psychological Age Nerve damage Blood flow disturbance (atherosclerosis) Low testosterone DM Medications ``` All can result in inadequate filling of the corpus cavernosa
130
How do you treat ED?
Phosphodiesterase inhibitors (PDE5) sustain NO stimulated cGMP levels in the penis Sildenafil (Viagra), Tadalafil (Cialis), Vardenafil (Levitra)
131
At high doses, PDE5 inhibitors can also activate PDE6, which does what?
PDE6 in the retina —> visual changes
132
Alternative therapies for ED if the dude doesn’t want viagra
Prostaglandin E (alprostadil) - self-administered intraurethral therapy or needle-injected Hormone replacement therapy Penis pumps Vascular surgery Penile implants Psychological counseling and sex therapy
133
What are the different forms of birth control available to men?
Condoms “The Withdrawal Method” Vasectomy
134
How do vasectomy’s work?
Surgical cut of each vas deferens with ligation of the ends Sperm can no longer move through the ejaculatory tract and out the penis Accessory gland function unaffected but semen contain no sperm Testosterone levels unaffected Sperms are removed from the epididymis through phagocytosis
135
What is the vasectomy reversal procedure called?
Vasovasostomy
136
What is Vasalgel?
A polymer gel that is injected into each vas deferens, thus blocking movement of sperm Proposed to be effective for several years, reversible with subsequent injection Currently in human trials but still several years away from FDA approval
137
Why do the little bitch ass men complain about endocrine methods of birth control?
Acne Increased body weight Decreased HDL And just like that, it’s not available in the US
138
What does marijuana do to male fertility?
Reduces it Endocannabinoid receptors are present in the HPG axis —> suppressive effect Endocannabinoid receptors also present in sperm —> decreased numbers, altered morphology, and reduced activity

Phys II Unit III (5 decks)

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