Male Reproductive Physiology Flashcards
FSH and LH from the anterior pituitary induce the testis to form
Testosterone
Inhibin
Both inhibit GnRH
Testosterone inhibits LH
Inhibit inhibits FSH
XY or XX is _______ sex
Testes or ovaries is the ________ sex
Internal and external genitalia is the ______ sex
Genetic sex
Gonadal sex
Phenotypic sex
Male internal genitalia is under the control of what hormone
Testosterone
External male genitalia is controlled by what hormone
Dihydrotestosterone
Androgen insensitivity syndrome
XY —> Testes
No testosterone receptors - no development of male internal/external genitalia
+ antimullerian hormone —> no Fallopian tubes, uterus, or upper vagina
Phenotypic female with short vagina, labia, and clitors
Develop breasts during puberty
Must remove testis to prevent malignancy
Main structures of testis
Seminiferous tubules
Produce sperm, contains Sertoli cells, spermatogonia, spermatocytes
Connective tissue/interstitial
Leydig cells produce testosterone, also contains mast cells, macrophages, nerves, BV, LN
Leydig cells are stimulated by what hormone of the anterior pituitary
LH
Sertoli cells are stimulated by what hormone secreted by the anterior pituitary
FSH
Exocrine functions of Sertoli cells
Secrete aqueous fluid into lumen of seminiferous tubules -> sperm transport from tubules to epididydmus
Produce androgen binding proteins - binds testosterone and concentrates it in the seminiferous tubules
Endocrine functions of Sertoli cells
Produce antimullerian hormone - regression of internal female genital ducts
Produces inhibit: inhibits FSH
Produces aromatase - converts testosterone to estradiol 17b
Supportive function of Sertoli cells
Provide nutrients into differentiating sperm (transferrin, Fe, lactate)
Form tight junctions - blood testes barrier
Function of leydig cells
Synthesize and secrete testosterone
Can make cholesterol de novo or acquire from circulation
Hormonal changes at puberty
Pulsatile GnRH secretion produces pulsatile FSH and LH secretion
Leads to sex steroid hormone secretion (testosterone)
Order of affinity of androgens (on androgen receptor)
DHT > testosterone > Androstenedione (very weak but still binds)
Active androgen in most target tissues
Testosterone
Androgen made in leydig cells —> seminiferous tubules —> peritubular capillaries —> peripheral circulation
Testosterone
_______ _______ protein binds testosterone in the seminiferous tubules to concentrate testosterone there
Androgen binding protein
Testosterone production begins at ____ weeks
7-8 weeks
Testosterone causes induction of _____ sex characteristics
Secondary
What are some secondary sexual characteristics induced by testosterone
Growth spurt Closure of epiphyseal plates Acne Increased muscle ass Deepening of voice Body hair Baldness Libido Growth of penis and seminal vesicles Increased BMR Increased RBCs
_____ is made from testosterone by the action of 5alpha reductase (enzyme)
dihydrotestosterone
During development, DHT directs the formation of _____ genitalia
External genitalia
5alpha reductase deficiency
At birth, male internal genitalia (testosterone) ambiguous external genitalia (no DHT)
At puberty: testosterone levels super high- asculinization and male external genitalia
Benign prostatic hyperplasia
Poorly understood pathogenesis but requires androgens
Enlargement of periurethral prostate lobes -> compress urethra
Storage and voiding symptoms
Not premalignant
Benign prostatic hyperplasia treatment options
1st line - alpha1 antagonists - relaxes smooth muscle in bladder neck and urethra
2nd line - 5alhpa reductase inhibitors - blocks conversion of testosterone to DHT
Testosterone can be aromatized to ______
Estrogens
Actions of estradiol
Bone maturation
Growth acceleration
Breast growth
Role in spermatogenesis
Male hypogonadism
Decrease in sperm/testosterone production
Primary - problem with testis, high LH and FSH
Secondary - problem with pituitary, low LH, FSH, low testosterone and sperm
Klinefelter is an example of ____________
Hypogonadismm
Klinefelter syndrome
Primary hypogonadys
47, XXY
Y chromosome gives male phenotype
Abnormal leydig function, low test, high LH, high estrogen
Seminiferous tubule dysgenesis
Infertility, decreased inhibin causes high FSH
Secondary hypogonadis (non functioning pituitary tumors)
Pituitary compression - low LH and FSH, low test, hypogonadism
Mass effect: visual symptoms, headache
Kallmann syndrome is an example of _______ hypogonadism
Secondary hypogonadism
Kallmann syndrome
GnRH neurons fail to migrate into hypothalamus during embryonic development - low GnRH secretion - low LH, FSH - low testosterone
Delayed/absent puberty
Infertility
Impaired sense of smell ss
Spermatogenesis occurs in the _____
Seminiferous tubules
Immature male germ cells
Spermatogoniia
As sperm cell precursors mature, they move closer to lumen/basolateral membrane
Lumen
Three phases of spermatogenesis
Mitotic divisions
Meiotic divisions
Spermiogenesis
As a result of mitotic divisions of spermatogenesis, the spermatogonia forms ____ _______ cells
2 primary spermatocytes
As a result of meiotic divisions of spermatogenesis, the primary spermatocytes (2 from before) under go ____ meiotic divisions to produce ____x _____________ with X amount of chromosomes
As a result of the second round of meiotic divisions, the cell types from above produce ___x _______ with x amount of chromosomes
Primary spermatocytes
2 secondary spermatocytes each haploid
2 spermatic each haploid
Spermatids undergo spermiogenesis to become
Mature spermatozoa.
What virus can cause testicular pain, scrotal swelling, erythema
Destroys epithelium of seminiferous tubules and ay impair fertility
Mumps
Cryptorchidsm
Undescendeed testes
Affects Sertoli cells, not leydig cells therefore
Testosterone is normal
Impaired fertility
Hormonal controls of spermatogenesis
Testosterone: growth and division LH: stimulation of testostorone FSH: stimulates Sertoli cells GH: early division fo spermatogonia Estrogen: probably also essential for spermiogenesis
Describe the movement of sperm
Seminiferous tubules Epididymus Vas deferens Prostate glands Seminal vesicles Ejaculatory duct Urethra Bulbourethral glands
In the epididymus, what maturation of sperm occurs
Motility is imparted
Decapacitation - addition of molecules to membranes to prevent premature acrosomal reaction
Seminal vesicles secrete fluid containing what molecules
Fructose, citrate, prostaglandins, fibrinogen
Noursh super
Prostaglandins important for fertilization
Prostate gland secretion functions
Produces slightly alkaline fluid containing citrate, phosphate, calcium, and enzymes
Neutralizes acidity of other seminal fluids
Improves motility
Aids in fertilization
Composition of semen
10% sperm
60% fluid from seminal vesicles
30% fluid from prostate
Small amount of fluid from bulbourethral gland
Primary mode of arousal
Sensory nerve signals from glans penis —> pudendal n —> sacral spinal cord
Secondary arousal centers
Anal epithelium
Scrotum
Perineal structures
Internal structures
What are the 3 erectile bodies in the penis
2 corpora cavernous and 1 corpus spongiosum
Relax for an erection
