Male Reproduction (ch. 28) Flashcards
1
Q
What is reproduction?
A
Reproduction is one of the basic life processes of living things.
2
Q
What can reproduction refer to?
A
Reproduction can refer to the formation of new cells for tissue repair, growth, or replacement.
3
Q
What does sexual reproduction involve?
A
Sexual reproduction includes the processes of fertilization of an ovum by a sperm to form a zygote, followed by repeated cell division and differentiation.
4
Q
What is the structure of the scrotum?
A
The scrotum is a bag of loose skin and subcutaneous tissue that holds the testes. It is divided into two compartments internally by the dartos muscle and a subcutaneous layer. Externally, a ridge called the raphe separates the two compartments.
5
Q
What are the muscles associated with the scrotum?
A
The scrotum contains the dartos muscle and the cremaster muscle.
6
Q
What is the function of the dartos muscle?
A
The dartos muscle wrinkles the scrotum to reduce heat loss.
7
Q
What is the function of the cremaster muscle?
A
The cremaster muscle pulls the testes closer to the body for warmth.
8
Q
What temperature is needed for normal sperm production?
A
Normal sperm production needs a temperature 2–3°C below body temperature.
9
Q
How do the muscles respond to cold temperatures?
A
In cold conditions, both the dartos and cremaster muscles contract to conserve heat. The cremaster moves the testes closer to the body, and the dartos tightens the scrotum.
10
Q
How do the muscles respond to warmth?
A
In warm conditions, these muscles relax, allowing the testes to cool.
11
Q
What is the key function of the scrotum and its muscles?
A
The scrotum and its muscles regulate testicular temperature for optimal sperm production.
12
Q
What is the scrotum?
A
A bag of loose skin that holds and protects the testes, located outside the body to maintain proper temperature for sperm production.
13
Q
What temperature is needed for sperm production?
A
2-3°C below normal body temperature.
14
Q
What are the two muscles that help regulate testicular temperature?
A
- Dartos muscle (wrinkles scrotum) 2. Cremaster muscle (moves testes closer to body)
15
Q
What are the two protective layers covering the testes?
A
- Tunica vaginalis (outer layer) 2. Tunica albuginea (inner fibrous layer)
16
Q
What is the size of normal testes?
A
About 5 cm long and 2.5 cm in diameter, weighing 10-15 grams.
17
Q
What are lobules and how many are in each testis?
A
Compartments within the testes containing seminiferous tubules; 200-300 lobules per testis.
18
Q
What happens in the seminiferous tubules?
A
Sperm production (spermatogenesis) occurs here.
19
Q
What is a hydrocele?
A
Fluid buildup in the tunica vaginalis, usually caused by injury or inflammation.
20
Q
When do testes typically descend into the scrotum during fetal development?
A
During the 7th month of pregnancy.
21
Q
What cells produce testosterone in the testes?
A
Interstitial (Leydig) cells.
22
Q
What types of cells are found in seminiferous tubules?
A
Seminiferous tubules contain two types of cells: spermatogenic cells and sustentacular cells.
23
Q
What is the function of spermatogenic cells?
A
Spermatogenic cells form sperm.
24
Q
What is the role of sustentacular cells?
A
Sustentacular cells support sperm.
25
What are spermatogonia?
Spermatogonia are spermatogenic cells that arise from primordial germ cells and remain dormant until puberty.
26
What is the progression of sperm cell maturity within spermatogenic cells?
The layers of varying maturity sperm cells begin with spermatogonia and end as mature sperm.
27
Where are sustentacular cells?
Sustentacular cells are embedded among the spermatogenic cells that extend from the basement membrane to the lumen of the tubule.
28
What is the function of sustentacular cells?
They nourish sperm and developing sperm cells and control the release of sperm into the lumen of seminiferous tubules.
29
What substances do sustentacular cells produce?
They produce fluid, inhibin, and regulate testosterone and FSH.
30
What is the blood-testis barrier?
The blood-testis barrier is formed by tight junctions of sustentacular cells and isolates developing gametes from immune responses to spermatogenic cells.
31
Why are surface antigens identified as foreign?
Surface antigens are identified as foreign due to the isolation provided by the blood-testis barrier.
32
How long does spermatogenesis take?
65-75 days
33
What cells start the process of spermatogenesis?
Spermatogonia (diploid stem cells)
34
How many chromosomes are in spermatogonia?
46 chromosomes (2n, diploid)
35
What happens to some spermatogonia during division?
They stay at the basement membrane as a backup reservoir for future sperm production
36
What do the other spermatogonia develop into?
Primary spermatocytes
37
Where are mature sperm cells released?
Into the lumen of the seminiferous tubule
38
What supports and nourishes developing sperm cells?
Sustentacular (Sertoli) cells
39
What is the blood-testis barrier?
Tight junctions between Sertoli cells that protect developing sperm from immune attack
40
Where do sperm cells mature?
In layers within the seminiferous tubules, becoming progressively more mature toward the lumen
41
What type of division do spermatogonia undergo?
Mitosis
42
What are spermatogonia?
Stem cells near the basement membrane that start sperm production through mitosis.
43
What happens when spermatogonia divide?
One remains as a stem cell; the other develops into a primary spermatocyte.
44
What type of cell is a primary spermatocyte?
Diploid (2n) cell with 46 chromosomes.
45
What happens during Meiosis I?
Primary spermatocyte divides into two haploid secondary spermatocytes.
46
How many chromosomes are in a secondary spermatocyte?
23 chromosomes (haploid, n), but each still has two chromatids.
47
What happens during Meiosis II?
Secondary spermatocytes divide to form four spermatids.
48
What is spermiogenesis?
The final stage where spermatids mature into spermatozoa (sperm cells).
49
What changes occur during spermiogenesis?
Nucleus condenses, tail develops, excess cytoplasm removed.
50
What is spermiation?
Release of mature sperm into the seminiferous tubule lumen.
51
Can sperm swim immediately after spermiation?
No, they need to travel through the male reproductive tract to gain motility.
52
How many sperm are produced daily?
About 300 million
53
How long is a sperm cell?
60 micrometers (μm)
54
What are the two main parts of a sperm?
Head and tail
55
How many chromosomes are in a sperm's nucleus?
23 chromosomes
56
What is the acrosome?
A cap on the sperm's head containing enzymes that help penetrate the egg
57
What are the four parts of the sperm's tail?
Neck, middle piece, principal piece, and end piece
58
What does the middle piece contain?
Mitochondria that produce ATP for movement
59
What's the function of the neck?
Contains centrioles and connects the head to the tail
60
How long can sperm survive in the female body?
Up to 48 hours
61
What's the main purpose of sperm?
To reach and fertilize an egg
62
What hormone does the hypothalamus release at puberty?
GnRH (Gonadotropin-Releasing Hormone)
63
What two hormones does GnRH trigger the pituitary to release?
LH (Luteinizing Hormone) and FSH (Follicle-Stimulating Hormone)
64
What does LH stimulate?
Interstitial (Leydig) cells to produce testosterone
65
What is testosterone made from?
Cholesterol
66
What is the main function of FSH?
Stimulates sperm production (spermatogenesis)
67
What is ABP?
Androgen-Binding Protein - keeps testosterone levels high near developing sperm
68
What produces inhibin?
Sertoli (nurse) cells
69
What is the function of inhibin?
Stops FSH production when enough sperm is made
70
What happens when sperm production is too low?
Less inhibin is released, allowing more FSH production
71
What is DHT?
Dihydrotestosterone - converted from testosterone in certain tissues
72
What does LH stimulate?
Testosterone production by interstitial cells in the testes.
73
How does testosterone regulate LH and GnRH?
By suppressing their release through negative feedback.
74
What does FSH do?
Works with testosterone to promote spermatogenesis.
75
What does ABP (Androgen-Binding Protein) do?
Binds testosterone to keep its levels high near developing sperm.
76
What produces inhibin?
Sertoli (nurse) cells.
77
What is the function of inhibin?
Decreases FSH release when enough sperm is made.
78
What is DHT (Dihydrotestosterone)?
A stronger androgen converted from testosterone in some tissues (like the prostate and external genitals).
79
What triggers the release of FSH and LH?
GnRH (Gonadotropin-Releasing Hormone) from the hypothalamus.
80
How does testosterone affect the body?
Drives male sex characteristics, supports sperm production, and helps with anabolic processes like protein synthesis.
81
Where do testosterone and DHT bind?
To androgen receptors in the nuclei of target cells
82
What are 3 main effects of testosterone during prenatal development?
1. Develops genital ducts 2. Controls testes descent 3. Influences brain development (when converted to estrogen)
83
What does DHT mainly control before birth?
Development of external genitals
84
Name 4 secondary sex characteristics developed at puberty:
1. Broad shoulders 2. Body/facial hair 3. Deeper voice 4. Increased muscle mass
85
What is anabolism?
Stimulation of protein synthesis, leading to increased muscle and bone mass
86
How does testosterone affect sexual function?
Controls sperm production, sexual behavior, and libido
87
What happens when testosterone levels get too high?
The body reduces GnRH and LH production to lower testosterone
88
What happens when testosterone levels get too low?
The body increases GnRH and LH production to raise testosterone
89
Does testosterone affect libido in females?
Yes, it influences sex drive in both males and females
90
What's the main difference between testosterone and DHT?
DHT is a stronger form of testosterone, especially active in developing male external features
91
What is the first duct that sperm enters after production?
Seminiferous tubules
92
What creates pressure to move sperm through the tubules?
Fluid from sustentacular (Sertoli) cells
93
What is the network of ducts after straight tubules called?
Rete testis
94
How long does sperm maturation take in the epididymis?
14 days
95
What is the length of the epididymis if stretched out?
6 meters
96
What lines the epididymis?
Stereocilia (microvilli)
97
How long can sperm be stored in the epididymis?
Several months
98
What type of movement pushes sperm through the ductus deferens?
Peristaltic contractions
99
What is the enlarged end portion of ductus deferens called?
Ampulla
100
What happens to old/damaged sperm in the epididymis?
They are reabsorbed
101
What is the path of sperm transport?
Seminiferous tubules → straight tubules → rete testis → efferent ducts → epididymis → ductus deferens
102
What is the spermatic cord?
A supporting structure that extends from the scrotum through the abdominal wall
103
Name 3 main components of the spermatic cord:
1. Ductus deferens 2. Blood vessels (testicular artery and veins) 3. Cremaster muscle
104
What other structures are in the spermatic cord?
Autonomic nerves and lymphatic vessels
105
What is the inguinal canal?
A 4-5 cm passage in the abdominal wall that the spermatic cord passes through
106
Where does the inguinal canal start and end?
Starts at the deep inguinal ring and ends at the superficial inguinal ring
107
What is the pampiniform plexus?
A network of veins that drain blood from the testes
108
What is a varicocele?
Swelling in the scrotum caused by enlarged veins; most visible when standing
109
How long is the inguinal canal?
4-5 centimeters (about 2 inches)
110
What muscle is contained in the spermatic cord?
The cremaster muscle
111
Where do the ejaculatory ducts form?
From the junction of the seminal vesicle duct and the ampulla of the ductus deferens.
112
What do the ejaculatory ducts eject?
Seminal vesicle secretions and then sperm (semen).
113
What is the function of the urethra in males?
It is a shared duct for both the reproductive and urinary systems, carrying semen and urine.
114
What substances pass through the urethra?
Semen and urine.
115
What are the three sections of the male urethra?
Prostatic urethra – Passes through the prostate gland.
Membranous urethra – Passes through the deep muscles of the perineum.
Spongy urethra – Passes through the penis.
116
What is the primary function of the ducts in the male reproductive system?
The ducts store and transport semen.
117
What percentage of the liquid portion of semen is secreted by the Seminal Vesicles?
60%
118
What percentage of the liquid portion of semen is secreted by the Prostate Gland?
25%
119
Which glands secrete the remaining liquid portion of semen?
Bulbourethral Glands
120
What are the three accessory glands in the male reproductive system?
1. Seminal vesicles
2. Prostate gland
3. Bulbourethral (Cowper's) glands
121
What do seminal vesicles secrete?
Alkaline, viscous fluid containing:
1. Fructose
2. Prostaglandins
3. Clotting proteins
122
What does the prostate gland secrete?
Milky, slightly acidic fluid containing:
1. Citric acid
2. Proteolytic enzymes
3. Acid phosphatase
4. Seminalplasmin
123
What is the main function of the prostate's secretions?
Contributes to sperm motility and viability
124
What do bulbourethral glands secrete?
Alkaline fluid and mucus for:
1. Neutralizing urine acids
2. Lubrication
3. Decreasing sperm damage
125
When do bulbourethral glands release their secretions?
During sexual arousal, before ejaculation
126
What is the shape of the prostate gland?
Donut-shaped
127
What is semen?
A mixture of sperm and seminal fluid.
128
What is the average volume of an ejaculate?
2.5-5 mL with 50–150 million sperm/mL.
129
What is the pH range of semen?
7.2–7.7.
130
What does seminal fluid provide for sperm?
A transportation medium, nutrients, and protection from hostile acid environments.
131
What happens to liquid semen after ejaculation?
It coagulates within 5 minutes and then reliquefies after about 10-20 minutes.
132
What are the two main functions of the penis?
1. Passageway for semen (reproduction)
2. Passageway for urine (excretion)
133
What is the glans?
The sensitive head (tip) of the penis covered by the prepuce (foreskin)
134
What is the prepuce?
The loose skin (foreskin) that covers the glans penis
135
What are the corpora cavernosa?
Two cylindrical structures that fill with blood during erection
136
What are the crura?
Tapered portions of the corpora cavernosa that anchor the penis to the pubic bone
137
What is the corpus spongiosum?
Tissue surrounding the urethra that prevents it from collapsing during erection
138
What is the bulb of the penis?
The rounded part at the root of the penis attached to deep muscles of the perineum
139
What is the function of the urethra in the penis?
To transport both semen and urine out of the body
140
Where is the external urethral orifice located?
At the tip of the glans penis
141
What provides structural support during erection?
The crura and the corpora cavernosa
142
What supports the penis?
Two ligaments that connect to the fascia (connective tissue) of the penis
143
How many cylindrical masses make up the penis body?
Three cylindrical masses
144
What are the two dorsolateral masses called?
Corpora cavernosa
145
What is the third cylindrical mass called?
Corpus spongiosum
146
What runs through the corpus spongiosum?
The urethra
147
What is the function of the corpora cavernosa?
They fill with blood during erection to provide rigidity
148
What is the function of the corpus spongiosum?
To protect the urethra from being compressed during erection
149
What is the protective covering around each cylindrical mass called?
Tunica albuginea
150
Where are the blood vessels and nerves located in the penis?
Along the dorsal (top) side of the penis
151
What are the main blood vessels on the dorsal side?
The deep dorsal vein and dorsal artery
152
What nerve system triggers an erection?
The parasympathetic nervous system
153
What chemical is released to start an erection?
Nitric oxide (NO)
154
What does nitric oxide do to blood vessels?
Causes vasodilation (widening) of arterioles in erectile tissue
155
What happens when arterioles dilate?
Large amounts of blood enter and fill the blood sinuses
156
What are the two main factors that cause an erection?
1. Increased blood flow 2. Widened blood sinuses
157
How is blood kept in the penis during an erection?
Expanded blood sinuses compress veins, slowing blood flow out of the penis
158
What type of sensory receptors can help trigger an erection?
Mechanoreceptors (touch receptors)
159
What is vasodilation?
The widening of blood vessels
160
Where does the increased blood flow during an erection?
Into the erectile tissue's blood sinuses
161
What maintains an erection once it occurs?
Compressed veins that slow blood from leaving the penis
162
What triggers ejaculation?
Sympathetic nervous system activation causes the powerful release of semen.
163
What muscles are involved in ejaculation?
The bulbospongiosus, ischiocavernosus, and superficial transverse perineal muscles contract to forcefully push the semen out of the urethra.
164
How is urine prevented from mixing with semen during ejaculation?
A smooth muscle sphincter at the bladder's base constricts to prevent urine from mixing with semen.
165
What happens after ejaculation?
The arterioles supplying the erectile tissues constrict, and the blood sinuses relax, allowing blood to drain from the penis.
166
What is the summary of the ejaculation process?
Ejaculation involves rhythmic muscle contractions to expel semen, a sphincter to block urine, and post-ejaculation changes to let blood flow out of the penis, ending the erection.
