WEEK 12: 12.1 Overview of Male Reproduction Flashcards
(44 cards)
What are the 3 main functions of the male reproductive system?
- Production of sperm cells in the testes
- Sustaining and transfer of sperm cell to the female
- Production of male sex hormones (like testosterone) which is essential for the normal function of the reproductive system & the male body form.
What is a penis?
A specialised organ that deposits sperm into the female reproductive system
What is a primary sex organ?
they are called the gonads, where gametes and hormones are produced
What are the gonads in males? and what do they do?
the testes, they produce sperm cells and male sex hormones (androgens)
What is a secondary sex organ? give examples of them
structures that are essential in caring for and transporting sperm cells
they include ducts (urethra, ductus deferens) which transport sperm
accessory sex glands (seminal vesicles, prostate gland, bulbourethral glands), which sustain sperm and the penis
where is the scrotum located?
extends from the body behind the penis
what is the sturcture of the scrotum
it is sac-like
divided into 2 compartments
each contains a testis
contains dartos muscle (thin layer of smooth muscle) beneath scrotal skin
2 skeletal cremaster muscles that descend from the abdomen and cover each testis
rich blood & nerve supply
What are the function of the scrotum
- support and protect the testes
- help regulate the temperature of the testes, maintained at about 35 degrees for optimal sperm production & storage
What is the location of the testes?
paired testes are located within the scrotum
What is the structure of the testes?
oval shaped
divided into compartments called lobules
seminiferous tubule- long tube where sperm is produced
lined by serous membrane that reduces friction
deep CT capsule
What is the function of the testes?
sperm cells and male sex hormones are produced within the testes
Describe the 3 distinct regions of a mature sperm cell
Head: contains compact haploid nucleus with little cytoplasm.
Acrosome covers most of head, is filled with lysosomal enzymes that help sperm penetrate coats around oocyte
Mid-piece: connects the sperm head to the flagellum. contains mitochondria, which provide energy required for sperm tail motility.
Flagellum: whip-like tail that moves the sperm along
What are the seminal vesicles and what is their function?
paired, pouch-like glands attached to the ductus deferens .
they secrete 60-70% of the volume of semen
they neutralise the acidic environment of male urethra and female reproductive tract
What are prostate gland and what is their function
single donut shaped gland, inferior to bladder and surrounding urethra
secrete milky prostatic fluid, contributes 20-30% of volume of semen
What are the bulbourethral glands and what is their function?
They are paired pea-sized glands at the base of the penis, connected to the urethra
secrete alkaline mucus into the urethra prior to ejaculation that neutralises the urethra from urine and lubricates the penis
What is semen made up of?
seminal fluid from the accessory glands, combined with sperm from testes
Describe the 3 segments of the penis
- root at base of penis, internal within body
- body/shaft - elongated and composed of 3 cylindrical columns or erectile tissue: 2 large corpora cavernosa on sides of penis + 1 corpus spongiosum on underside of the penis, that surrounds urethra
- bulbous glans at end of penis, has a high concentration of nerve endings and normally covered by foreskin
What is the function of the penis
to deliver semen to the female during intercourse and transport urine out of the body
Describe the mechanism of an erection
- sexual stimulation
- parasympathetic neurons release nitric oxide. this causes dilation of arteries leading to the penis, increasing blood flow into erectile tissues
- increasing pressure of arterial blood entering the vascular spaces of the erectile tissues compresses the veins of the penis, reducing flow of venous blood away from the penis
- blood accumulates in the vascular spaces within the erectile tissues of the penis
- following orgasm, sympathetic nerves contract the central artery of the penis and contract the smooth muscles around the erectile tissues, which expel blood out of the penis
Where is testosterone produced and by what
it is produced by Leydig cells of the testes, and production increases during puberty, initiating spermatogenesis and activating characteristic physical changes.
What are the functions of testosterone?
within the testes, to initiate and maintain spermatogenesis; low levels of testosterone can lead infertility
for development of male secondary sexual characteristics & maintaining sex drive (libido)
Describe the negative feedback loop that regulates testosterone levels
- the hypothalamus initiates spermatogenesis by secreting GnRH, stimulates the anterior pituitary to secrete FSH and LH
- LH stimulates interstitial Leydig cells to secrete testosterone. FSH stimulates sustentacular cells to secrete androgen binding protein. ABP binds to testosterone and becomes more concentrated in the seminiferous tubule, ensuring testosterone levels remain high in testes
- high level stimulates spermatogenesis, which causes negative feedback on GnRH prod
- sertoli cells respond to rising sperm by secreting inhbin, inhibiting FSH secretion from anterior pituatary, negative feedback cycle
- circulating testosterone level stimulates sex drive (libido) and develop secondary sexual characteristics
Where are testes located?
externally within the scrotum
What do testes produce?
sperm & hormones
