Reproduction 1 - MALE Flashcards
Pathway of sperm starting from testes
Testes (seminpherous tubules)—> efferent —> epididymis —> vas defran —> prostrate gland —> bulbo-utheral gland
—> urethra
Why are testes housed in scrotum?
Keeps temp 2 degrees lower then body temp to preserve sperm cells and their development.
Descent of testes
1) 3 months: in abdominal cavity.
- no penis, gubernaculum
2) 7 months: begin to descent towards scrotal sack
3) birth: by birth they descent
What happene if balls dont drop?
Cant produce sperm, can still produce hormones
Where is the site of gamete production for sperm?
Seminpherous tubules
Cells inside the seminiferous tubules?
Spermatogenetic cells:
- space in center / lumen
Which cells are effected by mumps?
Spermatogenic cells
What happened if you get mumps in childhood ?
- Cells that line outer periphery of each seminiferous tubule becomes smaller.
- size of cells decrease
- defects sperm production ability.
- vaccine
Cells of the testes: sites of sperm production
1) leydig cells
2) sertoli cells
3) smooth muscle muscles
4) blood test is barrier
Leydig cells
(Interstitial cells)
- secrete and produce testosterone
Sertoli cells
(Epithelial cells, make up seminiferous tubules)
- support sperm production
- linked together with tight junctions (where spermatogenesis occurs)
Smooth muscle (myloid cells)
- Contractile functions = seminiferous tubules contract to move sperm cell out via peristalsis
The important of the tight junctions is that it creates a
blood-testis barrier
blood-testis barrier:
Barrier protects junction (site of spermatogenesis) form any outside chemicals or antibodies or infections cuz of the protective barrier.
The tight junctions makes the barrier via two compartments, the
- luminal compartment
- basal compartment
Basal stretches like a ring which prevents anything coming form outside to coming inside.
Functions of Sertoli Cells
- Support sperm development: “trophic role” —> secrete factors
- Secrete luminal fluid in for sperm housing
- Secrete androgen-binding protein
• Androgen buffer (binds to androgens)
• Helps maintain steady [androgens] in lumen - Act as target cells for testosterone and FSH
• Secrete paracrine factors that stimulate spermatogenesis - Secrete inhibin
• Hormone of negative feedback loop for FSH - Secrete paracrine factors that affect Leydig cell function
- Phagocytosis of old and damaged sperm
- Site of immunosuppression
(blood testis barrier)
Testosterone and FSH use __________ as their target and help in __________
Sertoli cells
sperm development
Function of gonads
– Production of sperms
– Production of hormone
Epididymis function
– Maturation of sperm
– Storage site for sperm
Vas deferens function
– Conduit
– Storage site for sperm
Accessory sex glands function
– Production of seminal fluid
At what age do testes make testosterone?
Puberty (10-14)
How are hormones secretes regulated?
By Sertoli cells by producing androgen binding proteins
maintains testosterone
inhibin function?
Hormone of negative feedback loop for FSH = decreases FSH secretion.
Who produces inhibin
Sertoli cells.
Between the basal compartment and luminal compartment, which is bigger?
The luminal a lot bigger
Corticosteroid synthesis
Cholesterol —> progesterone —-> (aldosterone, cortisol, androgens)
Steroids are synthesized by________ and secreted by the _____
adrenal cortex
gonads
Steroids are ____ soluble hormones and gets easily
lipid
diffused through target cell membrane, often found in cytoplasm and nucleus.
Production of testosterone in leydig cell pathway
Cholesterol —> pregnenolone —> progesterone —> angdrogens (testosterone)
= leaves leydig cell and into blood
Once testosterone leaves the leydig cells in the testes and enters the blood, what does it convert to?
- testosterone
- Dihydrotestosterone (required for sex organic dev)
- estrogen
Patterns of Male Reproductive Activity Over the Human Life Span
Males never stop produce testosterone, levels changes with lifespan
Describe the peaks of testosterone secretion during male life span
1) second trimester of pregnancy: huge spike of testosterone during
2) neonatal period: (right after birth) spike before the age of 1.
3) puberty: large rise, then gradual decrease after age ~60. Never reaches 0.
What does the large spike of testosterone during neonatal period do?
final maturation of reproductive structures.
What regulates testosterone secretion of the leydig cells?
Hypothalamus (release GnRH) and ant. Pit. (Release FSH)
Role of hypothalamus and anti pituitary in regulating testosterone from the leydig cells
Hypothalamus (release GnRH) —-> ant pit (release FSH) —-> leydig cells (increase sec of testosterone)
Effects of androgens
- promote Porte in synthesis in skeletal muscle (anabolic effects / build cells)
- promote: spermatogenesis, secondary sex, sex drive, GH sec = bone growth, reproductive structures during embronic stage
Spermatogenesis starts where
In the basement membrane
Where does spermatogensis end?
Luminal membrane
Spermatogenesis pathway
1) Mitosis & differentiation: Spermatogonia (2n) divide = 2 cells, one splits, the other returns to germ cell to preserve # of cells.
2) Meiosis I: primary spermatocyte divide= 2 secondary spermatocyte secondary
3) Meiosis II: secondary spermatocyte divide = 4 spermatids (n)
4) 4 spermatids develop into 4 spermatozoa with tails and remain anchored to luminal membrane.
How long does spermatogenesis take?
64 days
Mitosis Ensures
continuous supply of spermatogonia
Meiosis function is for
Chromosome number becomes half
Differentiation and Packaging
• Specialization for transport and delivery of proper genetic material
Where does spermatogenesis occur
Seminiferous tubules, form basement to luminal membrane. Between adjacent Sertoli cells
Throughout the entire cell, spermatogensis is occurring and
different cells are at different stages of the process.
What is spermiogensis
A phase within spermatogenesis. The transformation form spermatids to spermatozoa.
How long does spermiogenisis take?
24 days
Spermiogensis pathway?
1) spermatid (1week) gets across all vesicle
2) across all vesicle grows, tail appears,
3) acrosome cap dev, sheds cytoplasm
4) spermatozoa with large tails, triangular shaped head / acrosomal cap, nucleus larger (week5)
Structure of spermatazoa?
1) head:
- nucleus
- acrosome (enzymes for fertilization)
2) midpiece:
- mitochondria
3) tail: whiplike movement
Are spermatoazoa able to move after spermatogensis ?
No not right away, tails immobile
Spermatozoa released into lumen
of seminiferous tubules:
- immobile For 20 days
How are sperm cells pushed out of seminiferous tubules?
pressure generated by the fluid secreted from sertoli cells pushes
the sperm and fluid to the epididymis
What occurs while sperms cells are in the epididymis ?
- 6-12 days
- acquire motility
- wave-like movement
- fluid reabsorbed and sperm concentrated
After sperm cells are moved to epidiymas, where do they go next and how?
Vas deferans via peristalsis
What occurs in vas deferans to sperm cells?
Stored until nut
Just because spermatogensis is happening doesn’t mean that the
produced sperm cells is good in size shape and number.
Does spermatogenesis indicate fertility?
The occurrence of Spermatogensis doesn’t mean fertility, cuz deformations of cells prevents fertilization. Need VIABLE sperm.
Gonadotropins in male reproduction
1) FSH
2) LH
Function of gonadotropins like FSH and LH?
1) FSH: stimulates spermatogenesis
2) FH: stimulates androgen secretion
Pathways for hormonal control of testosterone production:
Hypo-pituitary-testicular Axis
Hypothalamus (GNRH) ——> ant pit (LH/FSH) ——> testes (LH -> leydig cells / FSH -> sertoli cells) = testosterone by leydig and ABP and inhibin by sertoli
- GnRH release via pulse generator.
FSH targets ? Result?
The Sertoli cells of testes =andorgen binding proteins (ABP) sec. and inhibin
(-) feedback with ant pit w FSH.
LH target?
Leydig cells of testes = testosterone sec
(-) feedback on both hypothalamus and ant pit.
Androgen binding proteins ABP
Helps bind to testosterone and keeps action of testosterone enough to help with spermatogenesis
Inhibin function
Works on Ant. Pit. To inhibit FSH = inhibit sertoli stimulation.
Pulse generator
frequency and amplitude of these pulses change every 90 min for males
Pulse generator function?
keep the hypo and ant pit axis active,
causes the release of LH and FSH on a volatile manner
keeping the whole axis active. A constant level of GnRH = makes ant pit insensitive to GnRH and doesn’t keep axis active.
What ultimately regulated the rate of spermatonegsis?
The pulse generator and (-) feedback on the hypo and ant pit.
accessory sex glands
1) seminal vesicle
2) prostrate gland
3) Bulbourethral Gland
Role of accessory sex gland
Secrete seminal fluid
- 60% = seminal vesicle
- 30% = prostrate gland
- 10% = Bulbourethral Gland
Seminal fluid function
1) diluted sperm
2) provide E (fructose)
3) formation of semen clot
Seminal Vesicles function
• Secrete alkaline fluid with fructose, enzymes, and prostaglandins
Prostate Gland function:
- Secrete citrate and enzymes (PSA)
* Hypertrophy, biomarker for cancer
Bulbourethral Glands function:
• Secrete viscous fluid with mucus
What’s PSA
Prostrate specific antigen
An increase in PSA in the male body can be caused by the following:
1) A benign hypertrophy of the prostate gland (prostate gland enlarges and constricts urethra=pain)
2) If cancer growth in prostate gland (used a bio marker for detecting cancer)
Prostate specific antigen function:
Anti-clotting factor outside male body, allows sperm to escape and move up female tract.
Sexual responses are under what kind of control?
Controlled by autonomic nervous system
• Spinal Reflexes
Neural control of male sexual response
1) erection (parasympathetic)
2) emission (sympathetic)
- stimulate smooth muscle of ducts
3) ejaculation (somatic)
- rapid contraction of skeletal muscle = orgasm
What kind of feedback used for parasympathetic control of erection?
(+) feedback form outflow of blood decreasing —-> increase blood vol at erectile tissue
Viagra name ?
Sildenafil
Mechanism of vasodilation in reptile response / boner action
1) parasympathetic = INC nitric oxide (NT) ——>
2) increases cGMP ——>
3) vasodilation = inc blood flow = Erection
How does viagra work to make a erection?
Sildenafil inhibits phosphodiesterase, which is an inhibitor (breakdown cGMP).
Inhibit inhibitor = erection for long time.
What accounts for the low number of sperm to reach the site of fertilization?
There are 3 main possible reason why sperm levels are so low at the site of fertilization :
- Female tract pH is acidic = kills a large portion of sperm cells. (PRIMARY)
- Sperm dont have enough energy to exert enough movement to get to the fertilization site.
- When semen clot deposited in female genital tract, and as clot starts dissolving and sperms move forward, some of the sperm are lost from the female general tract.
Approx how many sperm make it to fertilization site?
100
Capacitation process
- destabilization of sperm surface membrane = fusion points fuse together with membrane of acrosome via acrosomal reaction.
- The enzymes contained in the acrosome are released which then cause the sperm head nuclear component to be delivered.
When does capacitation occur?
Occur once sperm arrive in female tract. ONLY occur in female body.
Before sperm have been in the female tract, their movement changes, how?
Sperm activated = Movement changes from being wavelike to whiplash = help get to fertilization site.
