M Physiology Basics Flashcards
What are the anatomical parts of the male reproductive system? Give a brief outline of the function of each part.
Scrotum - sac of skin which houses and protects the testicles Testis - production of sperm Epididymis - involved in the storage and transport of sperm Ductus (vans) deferens - transports sperm to the urethra Prostate - responisble for 30% of seminal secretions. Seminal Vesicle - 60% of seminal secretions Bulbourethral Gland - 5% of seminal secretions Penis - gets erect etc.
Outline the production of sperm in the testes.
The testes themselves are made of lobules of seminiferous tubules. Production occurs in the seminiferous tubules. These various tubules join at the rete testes forming efferent ductules which move into the epididymis, where sperm is stored.
How is there such a high number of sperm produced?
There is a high number of sperm produced due to the being between 300-900m worth of seminiferous tubules in the testes.
Where does the sperm go during ejaculation?
Sperm is stored initially in the epididymis. On ejaculation it moves through the ductus (vas) deferens, to seminal vesicles, prostate, bulbourethral glands and the urethra before expulsion.
What are Sertoli cells, what are their functions?
Cells found in the seminiferous tubules. - Form a blood-testis barrier (blood-seminiferous tubule barrier) - Isolate haploid spermatocytes, spermatids and spermatozoa from the immune system. - Physical movement of sperm towards lumen (Spermination). - Provides nutrients to the sperm - Removes waste from developing sperm. - Removes excess cytoplasm following cell divisions.
How long does it take to produce sperm? What important processes are occuring?
Around 75 days. Spermatocytogenesis Meiosis Spermiogenesis
How long does sperm be stored in the epididymis for? What important aspect of the sperm occurs here?
15 days The sperm become motile here. This is a very important aspect in terms of fertility.
What is the counter current heat exchange mechanism that occurs in the testes?
Arterial blood going to the testis enters a dense network of capillaries coming from the testis and epididymis before reaching the spermatic cord The arterial blood is cooled by the venous blood Helps maintain a constant testicular temperature
What are the various factors affecting spermatogenesis?
- Testis temperature - Should be 2°C below body temperature: Hyperthermia, mumps!, viral and other infections
- Endocrine: Reduction in gonadotrophins and androgens, anabolic steroids
- Loss of blood-testis barrier
- Physical damage, should not affect all seminiferous tubules
- Immunological reactions - Auto-immune reaction in men, NB sperm are haploid
- Environment: Occupation e.g. car industry, welders, plastic manufacture, pesticide sprayer, radiation
- Smoking, alcohol
- Medication - Some anti-hypertensives and anti-depressants, chemotherapy
What are the various targets in the body for androgens and what are the effects here?
Androgens go around the body and can affect various areas. Such as: - CNS - agressive behavious - Anterior Pituitary - Negative feedback, linked to release of FSH and LH - Penis - erection, copulation, ejaculatory effectiveness - Striated muscle - increased density - Prostate and seminal vesicle
What are the systemic impacts of hormone release?
Deepening of the voice Male body hair growth Increase sebaceous gland activity Protein anabolism
What are the reproductive hormones involved?
GnRH - gonadotrophin releasing hormone
Gonadotrophins: FSH and LH
Testosterone
Which cells in the testes produce testosterone?
Leydig cells
What is the role of follicle stimulating hormone in male repro?
Ultimately, spermatogenesis
What is the role of Leutenizing hormone in male repro?
To stimulate the testes to produce androgens (testosterone) which gives secondary male sex characteristics
