Reproductive System Physiology of Male Reproductive System, Summaries of Physiology

Download Reproductive System Physiology of Male Reproductive System and more Summaries Physiology in PDF only on Docsity! Human Anatomy & Physiology: Reproduction; Ziser, 2004 1 Reproductive System Function: producing offspring propagation of the species
in terms of evolution – the only reason all the other systems exist only major system that doesn’t work continuously
only activated at puberty unlike most other organisms on planet
mammals only reproduce sexually humans are dieocious
separate sexed (many animals are monoecious or hermaphrodites) in 7th week of embryonic development genes are activated that trigger differentiation of gonads Physiology of Male Reproductive System Testes primary reproductive organ of male consists of seminiferous tubules interstitial cells has dual function a. hormone secretion: interstitial cells
testosterone 1. development and maintenance of secondary sexual characteristics 2. stimulates protein synthesis 3. promotes growth of skeletal muscles b. spermatogenesis: seminiferous tubules
formation and maturation of sperm cells Male Accessory Organs three accessory glands secrete fluids that mix with the sperm = semen seminal vesicles (paired) secrete viscous liquid rich in fructose fructose serves as energy source for sperm prostate gland (single) Human Anatomy & Physiology: Reproduction; Ziser, 2004 2 surrounds ejaculatory duct at junction with urethra secretes an alkaline liquid that constitutes major portion of semen akalinity protects sperm for acidity of male urethra and female vagina bulbourethral glands (paired) small pea shaped glands below prostate also secrete alkaline fluid male hormone (=androgens) are secreted mainly by interstital cells of testes additional testosterone is secreted by Adrenal Cortex at puberty Ant Pituitary secretes FSH & large amounts of LH (ICSH) FSH & LH cause testes to increase in size and begin sperm production LH
also triggers testes to produce testosterone There are two male hormones: testosterone androstenedione main male hormone is Testosterone testosterone functions: 1. development and maintenance of secondary sexual characteristics hair pattern muscular development skeletal changes voice pitch 2. behavioral changes (~sex drive, aggression, courtship behaviors) 3. stimulates protein synthesis 4. promotes growth of skeletal muscles Androgens are also produced in women ovary & adrenal cortex relatively weak promotes protein synthesis, growth not masculinizing Negative feedback loop maintains constant level of testosterone in blood:
high testosterone levels inhibit LH Hypogonadism is present in 0.13% of males due to pituitary malfunction symptoms: retains juvenile physique; no secondary sex characteristics Human Anatomy & Physiology: Reproduction; Ziser, 2004 5 menstrual phase (days 1-6) shedding of uterie lining if no fertilization proliferative (follicular) phase (days 6-12) as follicle develops it secretes increasing amounts of estrogen endometrium cells proliferate ovulatory phase (days 12-16) ovulation
release of mature egg from ovary secretory (luteal) phase (days 16-28) follicle cells left behind after ovulation develop into corpus luteum corpus luteum secretes increasing amounts of progesterone continued increase in development of endometrium This cycle is tied to variations in several hormone Oogenesis the eggs develop within follicles under influence of FSH & LH from Ant. Pituitary egg antrum Graafian Corpus Corpus nest
follicle
develops
follicle
ovulation
Luteum
Albicans as follicle cells develop egg develops within mature (Graafian) follicle contains egg surrounded by fluid filled antrum egg undergoes meiosis but stops as secondary oocyte (metaphase II) until fertilization Mammary Glands during pregnancy breast development is stimulated by estrogen and progesterone secreted by placenta at birth shedding of placenta
cuts off source of these hormones
stimulates Ant. Pit. to secrete prolactin Prolactin stimulates lactation (devel of milk in glands) usually takes several days for full milk production Suckling of infant further stimulates secretion of prolactin oxytocin (from Post. Pituitary)
promotes ejection of milk into ducts +feedback: more suckling
more milk released Human Anatomy & Physiology: Reproduction; Ziser, 2004 6