Anatomy of the male reproductive system and Breast Flashcards
functions of the male reproductive system functions as a system
• Production, maturation, and storage of sperm
• Delivery of sperm into the female reproductive system
• Excretion of urine
Functions by organ(s)
• Gonads - Testes: produce sperm and testosterone
• Ducts: transport, store, and mature sperm
• Accessory sex glands: secrete liquid portion of semen
• Supporting structures -Penis: passage for excretion of urine and ejaculation of sperm
Structures of the male reproductive system
• Scrotum
• Testes
• Ducts:
Ductus deferens
Ejaculatory ducts
Urethra
• Accessory sex glands:
Seminal vesicles
Prostate gland
Bulbourethral glands
• Penis
Ducts of the male reproductive system
• Seminiferous tubules
• Epididymis
• Ductus (vas) Deferens
• Ejaculatory ducts
• Urethra
Ducts of the testes
• Continual release of sperm into the lumen of seminiferous tubules, and fluid secreted by the sustentacular cells propels them along the ducts
• Travel through convoluted seminiferous tubules to straight tubules distally and into a network of ducts called the rete testis
• Move then through efferent ducts into epididymis
Urethra
• The terminal duct
• Conveys both sperm and urine
• Passes through:
inferior portion of the prostate,
deep muscles of the perineum
Penis
• Opening is called the external urethral orifice
Accessory sex glands
• Seminal Vesicles
• Prostate
• Bulbourethral glands
Bulbourethral glands
• Produces fluids during arousal to protect
sperm:
- alkaline substance to neutralise acids in
urethra and vagina
- mucous to lubricate tip of penis an urethra
Penis
• Contains urethra as passageway for urine and
semen
• Method to deliver semen
• Consists of:
- Body
- Root
- Glans
• Supported by two ligaments continuous with
fascia of penis:
- Fundiform ligament; inferior part of linea alba
- Suspensory ligament of penis; from pubic
symphysis
Semen
• Mixture of sperm and semen made up of secretions from seminiferous tubules and accessory glands
• Provides medium to transport and give nutrients to sperm
• Also contains antibacterial agent to kill bacteria
Sperm production - Spermatogenesis
involves Mitosis and Meiosis
Mitosis – somatic cell division
• Stem cell (46 pairs of chromosomes) – divides into two daughter cells (23 pairs of chromosomes)
• Diploid cells – one stays a stem cell, one enters meiosis called primary spermatocyte
Meiosis – two cycles of division
• At then end of Meiosis I cells now 2 secondary
spermatocytes (23 chromosomes and a pair of
duplicate chromatids)
• Meiosis II produces 4 haploid spematids – each have 23 individual chromosomes (one from each pair)
• Last step of Spermatogenesis – each spermatid
matures into a spermatozoon (sperm) with a
flagellum (tail)
Takes about 5 weeks to complete
Breast
Male and female breast tissue is the same at birth
Normally it only functions in biological females
The changes occur due to the activity of hormones around puberty
Stimulation by oestrogen, growth hormone and insulin like growth factor (IGF-1) cause the increase in size in females
Male hormones prevent any further development
Gross anatomy of breast
• Generally, overlie the 2nd- 6th ribs
• Anterior to the pectoral muscle
Gross anatomy
• Medial border – sternum
• Lateral border – anterior or mid axillary line
• Superior border – infraclavicular fossa
• Inferior border – mid sternum
• Inframammary fold
• Breast parenchyma extends into the axilla
• Axillary tail
Gross anatomy 2
• Nipple – surrounded by areola – pigmented
• Dense fibrous tissue with smooth muscle fibres – erectile function
• Lies above the inframammary fold
• At the level of the 4th anterior rib
• The areola contains modified sweat glands
• Secretions lubricate during breast feeding
Internal anatomy
Internally there are 15-20 lobes
They are separated by connective tissue and
adipose tissue
Within each lobe there are around 20-40
lobules containing clusters of alveolar glands
The alveolar glands produce milk
Male breast tissue lacks these specialised
lobules
Internal anatomy of breast
• Milk passes from the alveolar gland to lactiferous ducts
• Lactiferous ducts open to the outside at the nipple
Ductal system
• Lined with epithelium
• Reduced friction for milk flow
• Middle myoepithelial cells aid in movement of milk
• Basement membrane outer layer of duct in contact with intralobular stroma
Blood supply
• The breast is highly vascular
• Predominantly supplied by internal mammary arteries derived from internal thoracic
artery
• Lateral thoracic and thoracoacromial arteries
(branches of the axillary artery) as well as posterior intercostal arteries (branches of the thoracic
aorta).
Venous drainage
• Venous drainage of the breast is mainly by the axillary vein
• The subclavian, intercostal, and internal thoracic veins also aid in venous drainage.
• Connections between the intercostal veins and the vertebral plexus allow metastasis of cancer to bones and to the nervous system
Lymphatic drainage
• Originates from lobules to subareolar plexus – Sappey’s Plexus
• 75% of lymph drainage to axillary nodes
• Drainage by 3 main routes
• The lymphatic drainage of the breast is of great importance in the spread of carcinoma
Lymphatic drainage route
• Axillary/Lateral
• Fed by Sappey’s plexus to pectoral group of axillarynodes
• Internal Mammary
• From lateral and medial
• Passes through pectoralis major
• May lead across median plane to contralateral
breast
• Retromammary
• Posterior part of breast
Breast development and physiology
• Mediated by levels of hormones
• Oestrogen, progesterone, prolactin, growth hormone, thyroid and parathyroid hormones, insulin and cortisol
• Oestrogen promotes increase in size by
• formation of mass of tissue under areola
• Increase in size and pigmentation of areola
• Development of lobular ducts
Cyclic
changes
- Oestrogen levels increase vascularity of breast tissue and stimulate proliferation of ductal and acinar tissue
- Effect sustained during luteal/secretory phase
- Progesterone levels increase and contribute to breast changes
- Dilation of ducts and conversion of acinar cells to secretory cells
- Breast volume may increase by 10 – 30mL
Pregnancy
• Breast remodels into milk- secreting organ
• Reaches ultimate mature developmental stage
• Increased oestrogen – lobules further differentiate
• Progesterone stimulates cells lining alveoli to produce milk
• Increased levels of prolactin – lactation
• Positive feedback
• Lactation
• Milk continuously secreted into alveolar lumen
• Stored until myoepithelial cells stimulated by
suckling – oxytocin – triggers let-down reflex
Post pregnancy
• Breast has capacity to regress to a resting stage after cessation of lactation and the undergoes same cycle of expansion and regression in subsequent pregnancies
Physiology – changes with age
- Premenopausal
- hormone levels decrease, glandular tissue shrivels or involutes, fat levels increase
- Postmenopausal
- HRT can cause glandular tissue levels to increase
- Weight loss can lead to prominence of glandular tissue due to the decrease in the amount of surrounding fatty tissue
