Anatomy & Physiology

Unit 12: Urogenital System

Male Anatomy

Testicles: 2 per male-located within the scrotum for temperature control

Have 2 functions: 1. Endocrine function: making

testosterone Interstitial cells: distinct cells that produce

testosterone 2. Exocrine function: producing sperm

Male Anatomy

Sperm Producing Structures (within testicles)

1. Seminiferous tubules Tubes coiled together to form lobules in

the testes “Sperm-forming factories”

2. Rete testesreceives sperm from seminiferous tubules

Male Anatomy

Sperm Producing Structures (within testicles)

3. Epidydimus Highly coiled, 20 ft. tube Sperm stay here for 20 days to mature Will contract w/ stimulation to expel

sperm

Male Anatomy

Sperm Producing Structures (within testicles)

4. Vas (ductus) Deferens Functions to propel sperm from storage to

urethra Runs from testes to pelvic cavity Enclosed in spermatic cord with blood

vessels—empties into ejaculatory duct Vasectomy: small incision through

scrotum to close off vas deferens

Male Anatomy

5. Urethra Runs from base of bladder to tip of penis Function: transports urine and semen Bladder sphincter closes upon ejaculation

so no urine is expelled and no semen enters the bladder

Male Accessory Organs

All contribute to the contents of semen Semen:

Milky, white and somewhat sticky Provides a transport medium & nutrients;

contains chemicals to protect the sperm Alkaline to protect sperm against acidity of

vagina

**sperm cannot swim in acidic environments

Male Accessory Organs

1. Seminal Vesicles Produces ~ 60% of fluid volume of

semen Full of vitamin C and sugar to nourish

sperm

2. Prostate Gland Gland below the bladder which surrounds

the urethra Adds a milky fluid to semen which helps

activate the sperm

Male Accessory Organs

3. Bulbourethral Gland Pea-sized gland Produces the pre-ejaculate: clear and

thick mucus that flushes through the urethra with stimulation, cleaning away acidic urine; also a lubricant

Male Anatomy: External Genitalia

1. Scrotum: a divided sac hanging outside abdominal cavity Holds testicles Can adjust location to be closer to body

when cold, and further when hot Sperm only produced when at a

temperature 3 degrees cooler than body temperature

Male Anatomy: External Genitalia

2. Penis: designed to deliver sperm into female; consists of: A shaft Glans penis: the tip covered by prepuce

(foreskin) Internally is the urethra and erectile tissue Erectile tissue fills with blood during an

erection

Female Anatomy

Ovaries: 2 small glands located in pelvic cavity Endocrine Functions: produce estrogen

and progesterone Exocrine Functions: make ova (eggs)

Female Anatomy

Ova Producing Structures: within ovaries1. Ovarian Follicles: tiny sacs that hold oocytes

(immature eggs) Surrounded by follicle cells Oocyte will mature here

2. Graafian Follicles: a mature egg which is ready to be ejected from the ovary during ovulation

3. Corpus Luteum: the ruptured follicle after ovulation

Usually degenerates unless fertilized

Female Anatomy

Duct System1. Uterine (Fallopian) Tubes Receives an ovulated oocyte and

provides a site for fertilization Does not actually come in contact with

ovary Fimbrae: finger-like projections which

wave to create a fluid current to direct oocyte to fallopian tubes

Female Anatomy

Duct System

2. Uterus (the womb) Hollow organ that receives, retains and

nourishes a fertilized egg Size of a pear in women who have not

been pregnant Cervix: narrow outlet of uterus

Female Anatomy

Uterus Continued There are 3 layers to the walls of the

uterus Endometrium: the inner mucosa layer of

uterus where fertilized egg burrows into and resides during development (implantation)

Myometrium: the muscular, middle layer which contracts during labor

Epimetrium: the outermost layer of uterus

Female Anatomy

Duct System

3. Vagina (birth canal) Thin walled tube, ~ 3-4 inches long Provides a passageway for the delivery

of an infant and for menstrual flow to leave body

Female Anatomy: External Genitalia1. Mons Pubis: fat pad over pubic bone2. Labia Majora: large folds of skin3. Labia Minora: smaller, more interior folds of

skin4. Clitoris: erectile tissue anterior to labia

minora junction5. Urethra: opening located between clitoris and

vaginal opening6. Perineum: area of skin between vaginal

opening and anus1. Episiotomy: the surgical cutting of perineum

during childbirth

The Menstrual Cycle

On average, takes about 28 days 3 stages

1. Menses (days 1-5) thick endomerial wall detaching from

uterus causes 3-5 days of menstrual flow

(bleeding)

The Menstrual Cycle

2. Proliferative Stage (days 6-14) endometrial wall repaired and blood

supply increased in response to rising estrogen levels

vvulation occurs on day 14 because of spike of blood LH levels

The Menstrual Cycle

3. Secretory Stage (days 15-28) endometrial gland secretion increases

nutrients within uterus progesterone levels high fertilization causes embryo to produce

hormone which maintains endometrial lining

no fertilization causes endometrial blood vessels to end its supply

menses occurs at day 28

Fertilization

The egg: only viable for 12-24 hours post-ovulation

The sperm: can remain fertile in female tract for 12-48 hours (sometimes up to 72 hours) Are attracted to chemical signals from the

egg For fertilization to occur intercourse must

happen 72 hours before ovulation or within 24 hours after

Fertilization

When the sperm reaches the oocyte: acrosomes rupture releasing enzymes to break away surrounding of oocyte First sperm in WINS!

Embryonic and Fetal Development

The zygote: the first cell created from fertilization

Cleavage: early stage of embryonic development Rapid mitotic divisions occur as embryo

moves toward uterus Morula: a solid ball of cells

Enters uterus around days 5-6

Embryonic and Fetal Development

Blastocyst: 100 cell embryo Hollowed out and filled with fluid Free floats in uterus Secrets human chorionic gonadoptropin

(hCG) hCG tells corpus luteum to keep up

hormone production **hCG hormone in urine used to detect

pregnancies

Embryonic and Fetal Development

By Day 7: late blastocyst stage Starts uterine attachment—embeds into

endometrium Cells start re-arranging themselves

1. trophoblast: the fluid filled sphere

2. Inner cell mass: small cluster of cells displace to one side

Embryonic and Fetal Development

Once placenta has formed (functional by third week) the mom’s blood supply is now connected to the babies via the umbilical cord

Nutrients are fed into the amnion (fluid filled sac) where baby develops

Embryonic and Fetal Development

Germ Layers form next (3)

1. Ectoderm: make up the nervous system and skin

2. Endoderm: forms mucosa and glands

3. Mesoderm: forms all else (muscles, bones, etc.)

Embryonic and Fetal Development

Week 3: placenta functions—delivers nutrients, disposes of wastes

Week 8: placenta making progesterone and estrogen to help maintain pregnancy Organ systems groundwork established

Week 9: now a fetus Growth and organ specialization Body proportions develop

Embryonic and Fetal Development

12 weeks: sex is discernable Month 4: looks human

Can suck lips and blink eyes Month 5: limbs near full-size

More muscular activity from baby Months 6 & 7

Weight increase Eyes open

The Mom

Anatomical Changes: Uterus crowds abdominal cavity Center of gravity changes Lumbar lordosis = back pain Relaxin causes pelvis to expand (ligaments

relax) Needs 300 extra calories daily

The Mom

Physiological Changes Morning sickness due to hormonal changes Heartburn because of displacement of esophagus Frequent and urgent urination—incontinence Nasal stuffiness (estrogen) VC increases –dyspnea Blood volume increases 25-40% Varicose veins

Parturition aka childbirth

Occurs ~ 280 days after last menstrual period Labor: series of events that expel infant from

uterus Triggers to induce labor:

High estrogen and low progesterone Braxton Hicks: weak contractions aka false labor False labor becomes actual labor when oxytocin

and prostaglandins are released

Parturition aka childbirth

3 stages of labor: Stage 1: Dilation

From true contractions to full dilation of cervix (10 cm.)

Contractions move in waves from superior uterus inferiorly

Amnion ruptures (water breaks)

Parturition aka childbirth

Stage 2: Expulsion Stage From full dilation to delivery Can take from 20 mins. to 2 hours Baby should exit head first Buttocks first is called breech

Parturition aka childbirth

Stage 3: Placental Stage Delivery of placenta Occurs within 15 minutes of birth Uterine contractions decrease bleeding

and afterbirth can be removed with a tug of the umbilical cord