Structure and function of male?

Label the different parts of the male scrotum

• multilayer pouch

– contains and

“protects” testes

• thin outermost layer

– darker in colour

• sweat glands

• at puberty, sparsely

cover with hair

WHat does the second layer of loosely organized

muscle and fibrous tissue do as part of your scrotum?

– not under voluntary control, but contracts with cold and sexual arousal

– wrinkled when contracted, but surface fairly smooth when hanging loose

Label the different parts of the testies?

WHere do testes develop?

In the abdominal cavity

WHat is cryptorchidism?

• failure to descend [1–7% at birth]

• usually self-corrects, but treatment may be necessary [1:500 in adult

What is the main function of the scrotum?

to keep the testes at the right temperature

• design features

– lack of fat

– small blood vessels near surface

– sweat glands

– vascular heat exchange system

oabout 3° C below normal body temperature of 37° C

• if excessive cold, testes drawn closer to body for warmth

What is spermatogenesis?

– gradual maturation process thru number of stages

– mature sperm  ½ genetic material

oother half from W’s egg [ovum]

fertilization combines both

sets of genetic material

What are the male sex hormones?

• androgens

– blood-borne chemicals

– Leydig's cells [interstitial cells]

between seminiferous tubules

• testosterone

the major male sex hormone

25

– other hormones from testes

What is the function of the epididymis?

acts as storage

[6 wks] / selection chamber

– less fit crowded to centre

where absorbed

What is the function of the vas

deferens?

vas deferens  firm cord

• two ejaculatory ducts

– thru prostate gland

• urethra serves dual function

• transport sperm & urine

What is the function of the prostate gland?

size & shape of large chestnut

– part of seminal fluid

ocharacteristic odour

– neutralize acidity of vagina

– aid in sperm transport

What is the function of the seminal vesicles?

substance initiates movement in sperm

What is the function of the Cowper's glands [bulbourethral glands]

– alkaline, clear, sticky substance

– neutralizes acidity of urethra

– normally no sperm but…

opregnancy possible

penetration without ejaculation

 Ninja sperm

young often very fertile

What are General Properties of Human Semen

Creamy texture; gray to yellow in colour

• Isotonic to blood serum [i.e., same concentration of salts as blood]

• Specific gravity: 1.028 [slightly heavier than water which is 1.000]

• Average volume: ~3 ml after 3 days of abstinence [2-6 ml]

• Fertility index [minimum qualification for male fertility]

At least 20 million sperm/ml seminal plasma [M = 120 million/ml]

At least 40% sperm must show vigorous progression

At least 60% sperm must be normal in shape and size

• pH [acidity/alkalinity]: 7.35–7.50 [slightly alkaline; 7.0 is neutral]

Describe the Penis?

• penis  male organ for copulation

• 3 parallel cylinders

– 2 cavernous bodies & 1 spongy body

oridge on underside of penis when erect

• irregular cavities [like dense sponge]

– engorged with blood when aroused

otough fibrous tissue surround cavernous bodies

stiffens penis when filled with blood

openis can “break” by sudden, forceful bending

ooften in highly arousing, unusual circumstances

[affair, motorcycle, public sex

Label the form and describe the function of the glans?

– smooth, round head

ofrom spongy body

– lots of nerve endings

oexquisitely sensitive

Label the form and describe the function of the coronal ridge?

Label the form and describe the function of the frenulum?

[strip connecting glans to body of penis]

– both particularly sensitive parts of penis

Describe the prepuce, foreskin?

– ordinarily retractable

otoo tight & will not retract

phimosis [cut it away]

Describe circucision?

• for ritual or sanitary reasons

• meta-analysis found some evidence that it may

enhance sexual satisfaction and erectile function

What is smegma?

cheesy deposit

Whats the average size of an erect penise?

5.2" inchs

50% of women say circumfrence matters more than length

erection reflex centres from where? From where to where? which discs?

in spinal cord

– input from nerves in penis to sacral 2-4

Can errection be turned off?

yes, severe stimulation; psychological

Describe the 4 steps in an erection

Describe an ejaculation?

• when arousal sufficiently intense

– impulses go to ejaculation centres

osame area of spine as erection centres

• ejaculation occurs

– expulsion of semen

– fluids from various parts

– rhythmic contractions moves the semen

– contraction of bulbocavernosus muscle at base of penis

• ejaculation and orgasm usually coincide

– but can be separable events

– infants appear to orgasm, but no ejaculation

– orgasm

ototal body response with rapid release of sexual tension

omore later