Reproductive Biology: Human Anatomy and Physiology

• Biomedical Perspective in Gender and Society covers aspects of anatomy and physiology of reproduction

Biological Sex

• A person with XX chromosomes usually has female sex and reproductive organs and is biologically assigned female
• A person with XY chromosomes usually has male sex and reproductive organs and is biologically assigned male

Puberty

• It is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction
• Boys and girls become sexually mature
• The menstrual cycle in females begins

Menstrual Phase

• This is the first stage of the menstrual cycle
• It happens when the ovum is unfertilized and does not implant itself into the uterine lining
• Levels of estrogen and progesterone drop

Proliferative Phase

• The proliferative phase of a woman's cycle typically lasts 14-18 days
• The lining of the tissue in the uterus proliferates
• Proliferation is when cells multiply and spread to build new tissue

Secretory Phase

• The secretory phase is the third and final phase of the uterine cycle

Female Characteristics

• Females are generally shorter than men
• Females have a greater proportion of body weight composed of fat than men
• Females have a lower mortality rate at every age and a longer projected lifespan than men

Biological Male

• Male sexual anatomy is designed for the production and delivery of sperm for fertilizing the female's ovum.
• Puberty signals the final development of primary and accessory organs that support reproduction.

Male External Genitalia

• Consists of the following structures
• Prepuce: The foreskin that covers the head of the penis, which can be removed via male circumcision
• Penis: Consists of the glans (head), shaft, and root and the glans, which is particularly sensitive to stimulation
• The length of the penis has the urethra surrounded by the spongy body and two cylindrical chambers known as the cavernous bodies, which become engorged with blood during arousal, resulting in erection
• Corona: The rim of the glans where it arises from the shaft
• Frenulum: A thin strip of skin connecting the glans and shaft on the underside of the penis
• Scrotum: The sac that encloses the two compartments housing the testes
• Urethral opening: found on the head of the penis and is the end of the tube connected to the bladder; it is used for urination and for internal structures to deliver semen when males ejaculate
• Perineum: The area of skin separating the genitalia from the anus, which is a greater distance in males than females

Male Internal Reproductive Organs

• Consists of the following structures
• Testes: Produces a large quantity of the androgen testosterone, which greatly influences male development and drives sexual motivation; it also produces countless sperm cells over the entire lifespan
• Vas deferens: Carries sperm from the testicle toward the urethra
• Seminal vesicles: Two glands that produce alkaline fluid rich in fructose sugar, comprising about 70% of semen volume; the Alkaline nature may stimulate sperm to start self-propulsion and sugar may provide sperm with nutrients; the ducts carry fluid and connects with vas deferens, forming ejaculatory ducts
• Ejaculatory ducts: Connect the vas deferens to the urethra
• Prostate: A gland producing alkaline secretions that account for about 10% of semen volume; the alkaline nature may counteract the acidic environment of the urethra and vagina, making them more hospitable for sperm; fluid passes through a series of ducts along the wall of the urethra
• Urethra: The tube within the penis that carries sperm and semen

Male Characteristics

• Males are generally taller and have a greater proportion of body weight composed of water
• Males proportionately have larger hearts and lungs to handle larger blood Quid volumes
• They have exposure to greater levels of testosterone, resulting in heavier bodies and more facial hair, but also increased frequency, degree of baldness
• They have a single X chromosome, resulting in sex-linked conditions like colorblindness and hemophilia

Male Hormones

• Testosterone is the main male hormone produced mainly by the testes, but the adrenal glands also produce some
• Even if testes are lost, the adrenal glands continue to produce testosterone to support physical male appearance
• Testosterone is responsible for growth and development during adolescence and for sperm and secondary sexual characteristics

Physical Changes in Males During Puberty

• Growth of facial and body hair
• Deepening of the voice
• Growth of the genitals
• Increase in height and muscle mass
• Development of acne