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What is the difference between sexual and asexual reproduction?
Sexual reproduction- requires two parents, offspring will inherit genes (1/2 DNA) from both.
Assexual reproduction: reproduction by mitosis, replicate itself by binary fission, happens in bacteria and other single cell organism.
Which cell determines gender (sperm or egg)
Y chromosome in sperm.
How many chromosomes do humans have?
Human: 46
Autosomes: 22
Sex chromosome- 1 chromosome
The mesonephruc ducts develop in which gender?
(wolfin) males reproductive tract.
The paramesonephric ducts develop in which gender?
(Mullerian) female reproductive tract.
What hormone is androgen?
Testosterone.
What is the function of SRY gene?
Sex determination in Y chromosome found only in males. SRY codes for TDF protein that initiates testes formaiton testosterone secretion begins at 8-9 wks, it also secretes mullerian=inhibiting factor that degenerates the paramesonephric ducts (X chromosome)
What does TDF do?
Initiates the development of testes
What is MIF? what does it do and where does it come from?
MIF causes degeneration of the paramesonephric ducts ( the X female chromosome) that is secreted by the testes.
When does sexual differentiation begin? end?
It begins at 5-6 wks and is completed by 10-12 wks post fertilization.
Know which embryonic tissues become what parts of the reproductive system in both genders (external) if androgen is present or not present.
Genital tubercle- glans penis if androgen is present clitoris if not present
Urogenital fold- tubes that surround urethra if androgen is present labia minora if not
Labioscrotal fold- scrotum if androgen present and labia majora if not.
What is androgen insensitivity syndrome?
A female that shows all usual changes of puberty (breast) but fails to menstruate, has presence of testes in abdomen, XY (male) chromosomes, has testosterone levels, but external genitalia has developed the female anatomy, but has no uterus therefore no menstrual cycle.
What is cryptochidism?
When 1 or both testes have not descended by birth, usually it will correct itself by the 1sr yr, of not an injection or surgery can draw the testes, of left uncorrected it may lead to sterility or testicular cancer.
What is the function of the scrotum?
(It is a puch like that holds the testes)allows teses to descend differently so they do not compress against each other, has a medium septum that divides them, has spermatic cord that contains vas deferens, blood and lymphatic vessels and testicular nerves, it also does thermal regulation.
Why do the testes have to be at a lower temperature than the core body temperature? How is this done?
Testes have to be at a cooler temp(37º) in order to produce sperm. it is regulated in 3 different ways;
Cremaster: it moves them upward (cold temp) or downward in (warm temp)
Dartos: does surface control, contracts when cold wrinkles the scrotum, holding testes against warm weather, reduces surface area of scrotum and heat loss.
Pampiniform plexus: network of veins in testes, does countercurrent heat exchange, testicular artery cools it (37º away from body and testicular vein brings the warm blood in)
What is the function of the testes?
Testes are endo/exocrine, that secrete hormones and sperm. contains the seminiferous tubules that produce sperm protected and supported by the nurse cells, the endocrine cells between tubules produce testosterone.
What does LH do in males?
it produces testosterone.
What is the correct pathway that sperm take from the testes to the urethra?
Testes contain efferent duct (moved by 12 sm ciliated ducts because sperm are not mobile yet)—> to the epididymis (site of maturation takes 12 days to mature and may be stored for 40-60 days, if not ejaculated it will be reabsorbed by epidiymis or released in urine)—> Vas deferns ( a muscular tube begins at epidiymis goes behind bladder and ends in seminal vesicle)—> Ejaculatory duct ( from vas deferens and seminal vesicle passes through prostate to empty in urethra.
What do the interstitial/leydig cells do?
they produce testosterone.
What do the sertoli/sustentacular cells do/
Cells that support and protect the sperm production.
What is the blood -testies barrier? What is its function?
Formed by tight junctions between sertoli (nurse) cells, separate sperm from immune system, they protect the sperm from beong destroyed because germ cells are immunologically different from body cells and would be destroyed by immune system.
Know the 4 spermatic ducts (in order)
Efferent ductules
Epididymis
Vas deferens
Ejaculatory duct
What is the function of the epididymus?
Site of sperm maturation (takes 12 days to mature) and storage (stores it for 40- 60 days), dies reabsorption of sperm that is not ejaculated.
What are the 3 accessory glands and what do they produce?
Seminal vesicle- main one, form 60% of components of semen
Prostate- thin milky secretion forms 30% of semen, may cause prostatic disease/ cancer
Bulbourethral glands= during arousal it produces a clear slippery fluid that lubricates the head of the penis during intercourse, protects sperm from the acidity in urine in the urethra.
(other 10% of semen are in sperm cells)
What is puberty?
Few years of adolescence until first menstrual period/first ejaculation of viable sperm in boys.
How do we define adolescence?
Onset of gonadotropin secretion and reproductive development ( full height)
What hormones trigger puberty?
Pituitary gonadotropin awakens the reproductive system leading to onset of puberty GnRH`
What are the differences between mitosis and meiosis?
Mitosis- serves as a stem cell (stencil) to keep making Type B spematogonium it remains in the tubule wall.
Meiosis- recombines genes reduces chromosome number by ½ while producing four daughter cells that become sperm cells with flagella.
What is spermatogenesis?
(formation of) process of sperm production in seminiferous tubules.
(What is the difference between type A spermatogonia and type B?
Type A spermatogonium- the stem cell that remains in the tubule wall
Type B spermatogonium- moves away from the wall to do meiosis and become secondary spermatocyte and divide and produce sperm.
What is spermiogenesis?
Changing of cell shape.
How many sperms do we get from 1 gamete cell?
4
Know the different parts of the spermatozoon and their function.
Head;
Nucleus that contains haploid set on 23 chromosomes that pair up with the 23 from the egg.
Acrosome: enzyme cap necessary to penetrate egg.
Basal body; end of nucleus where tail attaches
Tail:
Midpiece- contains mitochrondria that produces ATP and gives power to tail.
Principle piece: is axoneme surrounded by sheat of supporting fibers, makes most of tail.
End piece: tip of flagella
Know the component of semen.
60% seminal vesicle: viscous yellowish fluid, contains frucose and carbs feed mitochrondria to produce ATP and produce energy for sperm. Prostaglandins: stimulate female reproductive contraction to help move sperm up uterine tube, Proseminogelin: clotting enzyme that liquifies sperm
30% prostatic fluid: thin, milky white fluid that contains calcium, citrate, and phosphate, clotting enzymes that help it adhere to the female reproductive tract after ejaculation, also contains serine protease to reliquify semen so sperm have more motility and penetrate for fertilization.
10% sperm and spermatic duct secretion