Human Development Lecture 5: Sexual Response & STDs

Vocabulary flashcards covering the phases of sexual response, erectile physiology, key researchers, drug treatments, and sexually transmitted diseases discussed in Lecture 5.

Sexual response cycle

The sequential pattern of human sexual arousal consisting of excitement, plateau, orgasm, and resolution phases.

Excitement phase

Initial stage of sexual arousal marked by vasocongestion (sex flush), increased heart rate, and heightened sensitivity of sexual organs.

Plateau phase

Intermediate stage where physiological changes intensify; breathing rate peaks and muscles may twitch or clutch.

Orgasm phase

Stage characterized by rhythmic muscular contractions and, in males, ejaculation; peak of sexual pleasure.

Resolution phase

Final stage in which blood pressure, heart rate, and breathing return to normal and the body relaxes.

Refractory period

Time after orgasm during which males (and some females) cannot be restimulated to orgasm.

Vasocongestion (sex flush)

Engorgement of tissues with blood during sexual arousal, producing a reddish skin flush.

Vasodilation

Widening of blood vessels that increases blood flow; essential for erectile responses.

Ejaculation

Expulsion of semen from the male urethra, typically occurring at orgasm.

Erectile dysfunction (ED)

Persistent inability to achieve or maintain an erection sufficient for sexual activity.

Viagra (sildenafil)

First FDA-approved oral ED drug; a PDE5 inhibitor that prolongs nitric-oxide-mediated vasodilation; lasts ~4 h.

Cialis (tadalafil)

Long-acting PDE5 inhibitor for ED; enhances nitric-oxide effects and can last ~36 h.

PDE5 inhibitor

Drug class that blocks phosphodiesterase type 5, preserving cGMP levels and promoting penile vasodilation.

Nitric oxide (NO)

Gaseous signaling molecule released by endothelial cells that relaxes smooth muscle and increases blood flow.

Corpora cavernosa

Paired erectile tissue columns in penis and clitoris that fill with blood during arousal.

Clitoris

Female erectile organ homologous to the penis; contains ~8,000 nerve endings and extensive internal structure.

Masters and Johnson

Researchers (1950s–1990s) whose work defined the human sexual response cycle; dramatized in 'Masters of Sex.'

Alfred Kinsey

Pioneer of sex research (1930s–40s) who conducted large-scale surveys of human sexual behavior.

Pathogen

Any disease-causing organism such as bacteria, viruses, protozoa, or parasites.

Sexually transmitted disease (STD)

Disease resulting from a pathogen acquired through sexual contact; may show symptoms.

Sexually transmitted infection (STI)

Infection acquired sexually; may be asymptomatic until it manifests as an STD.

Bacteria

Single-celled organisms; some cause STDs like gonorrhea, chlamydia, and syphilis.

Virus

Microscopic infectious agent; responsible for STDs such as HPV, herpes, HIV, and hepatitis B.

Protozoan

Single-celled eukaryote; can cause STIs like Trichomoniasis.

Crab louse

Parasitic insect (Pthirus pubis) that infests pubic hair and spreads through close contact.

Mites (scabies)

Tiny arthropods that burrow into skin, causing an itchy rash; can be transmitted sexually.

Syphilis

Bacterial STD caused by Treponema pallidum; progresses through primary, secondary, latent, and tertiary stages.

Gonorrhea

Bacterial STD caused by Neisseria gonorrhoeae; can infect urethra, cervix, throat, or eyes.

Chlamydia

Most frequently reported bacterial STD in the U.S.; caused by Chlamydia trachomatis and often asymptomatic.

Herpes simplex virus

Viral STI causing recurrent genital or oral lesions; exists as HSV-1 and HSV-2.

Human papillomavirus (HPV)

Most common STI; >150 types, some cause genital warts or cancers; usually cleared by immune system.

HIV / AIDS

Virus that attacks immune cells; untreated infection progresses to acquired immunodeficiency syndrome (AIDS).

Genital warts

Fleshy growths on genital tissues caused by certain low-risk HPV strains.

Cervical cancer

Malignancy of cervix strongly linked to persistent high-risk HPV infection.

Pap test

Cytological screening that detects precancerous cervical changes to prevent cervical cancer.

HPV test

Detects presence of high-risk HPV DNA on the cervix; complements or replaces Pap test in screening.

Gardasil vaccine

Recombinant HPV vaccine using viral proteins to stimulate immunity; most effective before sexual debut.

Most common STI in U.S.

HPV is the most prevalent sexually transmitted infection among sexually active Americans.

HPV prevalence

CDC estimates that ≥75 % of reproductive-age people have been exposed to sexually transmitted HPV.