1. Male Sexual Anatomy and Physiology
Chapter 4

2. Learning Objectives External Sex Organs Internal Sex Organs
Health Problems of the Urogenital System
Male Sex Functions

3. External Sex Organs The Penis
Male sex organ used in sexual intercourse
Serves as conduit for urine and sperm
Contains cylinders of spongy material

4. External Sex Organs Penis Glans Corona Frenulum Root Shaft Foreskin
Highly sensitive tip of the penis
Corona
Ridge that separates the glans from the body of the penis
Frenulum
Sensitive strip of tissue that connects the underside of the penile glans to the shaft
Root
Base of the penis that extends into the pelvis
Shaft
Body of the penis that expands as a result of vasocongestion
Foreskin
Loose skin that covers the penile glans (prepuce)

5. External Sex Organs Circumcision Surgical removal of the foreskin
Has religious roots
Performed for health reasons
Painful but not remembered
May lessen sexual sensations
What are the similarities and differences between male circumcision and female circumcision (clitoridectomy). Can one logically favor one of these practices over the other?
Critical Thinking

6. Penis Size External Sex Organs
Cultural measure of masculinity and prowess
Range in size
Flaccid – 3 to 4 inches
Erect – 5 to 7 inches
Penis Size

7. Penis Size External Sex Organs
Surveys indicated most woman (85%) are satisfied with the size of their partner’s penis
55% of men are not satisfied with the size of their penis
Penis Size

8. External Sex Organs Scrotum
Pouch of loose skin located below the penis
Contains the testes
Spermatic Cord
Suspends testicle within the scrotum
Contains vas deferens, blood vessels, nerves, cremaster muscle
Raise and lower testes in response to temperature changes
Dartos Muscle
Contracts and relaxes in response to temperature changes
Increase or decreases surface area of the scrotum

9. Internal Sex Organs Testes
Males sex glands (gonads), suspended in the scrotum
Produce sperm cells and male sex hormones

10. Internal Sex Organs Testosterone Male steroid sex hormone
Secreted by interstitial cells
Stimulates
Prenatal differentiation of male sex organs
Development of secondary sex characteristics
Production regulated by pituitary hormones
LH stimulates secretion of testosterone
FSH regulates sperm production

11. Internal Sex Organs Sperm Seminiferous tubules Spermatogenisis
Tiny, winding, sperm-producing tubes within the lobes of the testes
Spermatogenisis
Process by which sperm cells are produced and developed
Spermatozoa are mature sperm cells
Epididymis
Tube that lies against the back wall of each testicle and stores sperm

12. Internal Sex Organs Vas Deferens
Tube that conducts sperm from the testicle to the ejaculatory duct of the penis
Vasectomy
Sterilization procedure in which the vas deferens is severed
Prevents sperm from reaching the ejaculatory duct
Removes sperm but not fluids from the ejaculate

13. Internal Sex Organs Seminal Vesicles
Two small glands that lie behind the bladder and secrete fluids that combine with sperm in the ejaculatory duct
The fluids produced are rich in nutrients to help ensure sperm motility

14. Internal Sex Organs Prostrate Gland
Lies beneath the bladder and secretes fluid that gives semen its characteristic odor and texture
Prostrate fluid is alkaline
Neutralizes some acidity in vaginal tract
Prolongs life of sperm

15. Internal Sex Organs Cowper’s Gland Lies below the prostrate
Secretes clear, slippery fluid into the urethra during sexual arousal
Secretion may reduce male acidity and also lubricate passageway for sperm
Not enough produced to lubricate the vagina during intercourse
Also known as the bulbourethral glands

16. Internal Sex Organs Semen Whitish fluid that constitutes the ejaculate
Consists of sperm and the fluids secreted by the seminal vesicles, the prostate gland, and the Cowper’s glands
70% from seminal vesicle
30% sperm and other fluids
Sperm only 1%, million sperm

17. Health Problems of the Urogenital System
Bladder and urethral inflammations
Strong need to urinate
Burning sensation
Frequent urination
Penile discharge
Prevention
Drink more water, cranberry juice
Lower intake of alcohol and caffeine
Urethritis

18. Health Problems of the Urogenital System
Relatively rare
About 8,000 cases per year, 350 deaths
Most common form of solid-tumor cancer for men 20-34
No evidence cancer results form sexual over-activity or masturbation
Favorable prognosis if detected early
Five year survival rate 99% if detected before spreading
Cancer of the Testes

19. Health Problems of the Urogenital System
Self Examination of the Testes
Lump on testicle
Enlargement or swelling
Change in consistency
Dull ache in lower abdomen or groin
Self-examination is best performed shortly after a warm shower or bath, when the skin of the scrotum is most relaxed.
Roll each testicle gently between the thumb and fingers.
Lumps are generally found on the front or side of the testicle.

20. Health Problems of the Urogenital System
Non-cancerous enlargement of the prostrate due to hormonal changes associated with aging
Symptoms include
Frequent and urgent urination
Difficulty starting and stopping flow
Benign Prostatic Hyperplasia (BPH)

21. Health Problems of the Urogenital System
Inflammation of the prostate
Symptoms include
Ache or pain between scrotum and anal opening
Painful ejaculation
Prostatitis

22. Health Problems of the Urogenital System
Second most common form of cancer among men
Second leading cause of cancer deaths in men
Risk factors include age, family history, gene mutations, and race
Symptoms include problems with erection, urinary frequency and urgency, blood in urine, pain or burning when urinating, pain in lower back or extremities, loss of bladder or bowel control
Early diagnosis can provide treatment before spreading
Not necessarily lethal
Cancer of the Prostate

23. Male Sexual Functions Erection
Engorgement of the penis with blood causing it to stiffen and widen
Reverses when blood begins to flow out
Affected by psychological factors
Performance anxiety
- Feelings of dread connected with an activity
Possible throughout the lifetime

24. Male Sexual Functions Spinal Reflexes & Sexual Response
Sexual reflexes are automatic, unlearned responses to sexual stimulation
Need not try to be aroused
Spinal reflexes do not require direct participation of the brain, but brain can trigger a spinal reflex
Erection and ejaculation
Erection center is located in the sacrum
Erection is possible even with spinal injury

25. Male Sexual Functions Role of the Brain Regulates sexual responses
Sends impulses to the erection center in the upper back
Relay center between brain and penis that allows perceptual, cognitive, and emotional responses to contribute to erection
If connection is inoperable, men fail to achieve erection solely by mental stimulation
Men require more sexual excitation to achieve full erection as they age
Brain can also stifle a sexual response

26. Male Sexual Functions Role of the autonomic nervous system (ANS)
Division of the nervous system that regulates automatic bodily responses, such as erection
Sympathetic
Branch of ANS most active during emotional responses that spend the body’s energy
Largely controls ejaculation
Parasympathetic
Branch of ANS most active during processes that restore the body’s energy
Largely controls erection

27. Male Sexual Functions Pyronie’s Disease Priapism
Erectile Abnormalities
Pyronie’s Disease
Excessive curvature that makes erections painful
Priapism
Erections that persist for hours
Causes include leukemia, sickle cell disease, diseases of the spinal cord
Dangerous due to lack of oxygen to penile tissue

28. Male Sexual Function Critical Thinking
Since erection and ejaculation are reflexes, how is it that people can consciously cause them to happen?

29. Male Sexual Functions Ejaculation Spinal Reflex Orgasm
Peak of sexual excitement
Release of tension
One can ejaculate without orgasm
Ejaculation

30. Male Sexual Functions Ejaculation Emission phase
Involves contractions of prostate, seminal vesicles, and upper part of vas deferens
Fluid is propelled into the urethral tract
Expulsion Phase
Muscles at base of penis and elsewhere contract, forcing out semen and providing pleasure

31. Retrograde Ejaculation
Male Sexual Functions
Retrograde Ejaculation
Ejaculate empties into the bladder
Sphincter actions are reversed
Results in dry orgasm
Can result in infertility, but otherwise harmless