Anatomy Unit 5

Primary and Secondary Sex Organs

Male: primary: testes secondary: sperm cell
Female: primary: ovaries, secondary: oocyte

Fertilization

union of the male and female gametes that result in the formation of a zygote

Key differences in the male and female urethra

Male: used in both the urinary and reproductive system, common pathway for ejaculation of semen and excretion of urine
Female: used only in the urinary system, only used for urine excretion

Anatomical composition of the penis (3 cylinders)

2- corpus cavernosum (erectile tissue) 1- corpus spongiosum (surrounds spongy urethra)

Glans Penis

the distal tip of the penis that is highly innervated with sensory receptors

Prepuce

superficial structure that covers the glans penis (aka foreskin)

Scrotum

double layer sac that contains the testes and regulates their temperature.

Ductus Deferens

transports sperm from the testes to the prostate

Testicular artery

supplies oxygen rich blood to the testes and epididymis

Testes

site of spermatogenesis

Urinary bladder

stores urine

Seminal vesicle

production of alkaline, nutrient-filled fluid required by sperm for their survival and effective motility, and contributes to most semen volume.

Prostate

contributes fluid and nutrients to the semen; site of union between seminal and urinary tracts

Rectum

terminal end of the digestive system

Name the structures that travel within the spermatic cord

ductus deferens, blood and lymphatic vessels, sensory and motor nerves

Significance of temperature regulation of the testes

Spermatogenesis can only occur at a certain temperature that is less than the body temperature. Maintained from the dartos muscles, cremaster muscle and pampiniform plexus of veins

Dartos muscle

muscular layer of the scrotum; contraction of this muscle decreases the surface area of the scrotum to decrease release of heat (crunching up)

Cremaster muscle

cord-like muscle within the spermatic cord; contraction of the muscle raises the testicles toward the body to warm them (elevation/depression)

Pampiniform Plexus of Veins

venous network surrounding the arteries entering the scrotum; close relationship of the cold venous blood decreases the temperature of the warm arterial blood prior to entering the testes

Spermatogenic cells

precursors to sperm cells

Sertoli cells

nourish spermatids as they develop into sperm

Leydig cells

produce testosterone

Spermatogenesis

production of sperm via meiosis using a reservoir of stem cells

Spermiogenesis

maturation process of the sperm in preparation for ejaculation

Describe the process of spermatogenesis

This is the process of production of sperm which occurs in the seminiferous tubules of the testes.

Genetic profile of a mature sperm cell

A sperm cell is a haploid (n) gamete containing 23 single chromosomes.A zygote is a diploid (2n) containing 23 paired chromosomes (46 total)

4 key events that occur during spermiogenesis

1. shed excess cytoplasm

2. increase number of mitochondria to increase the sperms capacity to produce ATP, which powers the flagella

3. development of the acrosome (contains enzymes that help the sperm gain access to the oocyte)

4. development of the flagellum

Luteinizing hormone

stimulates Leydig cells to secrete testosterone

Follicle stimulating hormone

stimulates sertoli cells to secrete androgen binding hormone that traps testosterone in the seminiferous tubules, promoting spermatogenesis.

Inhibin

hormone produced by Sertoli cells that inhibits the secretion of follicle-stimulating hormone (FSH) from the pituitary gland.

Testosterone

regulation of muscle mass, fat distribution and RBC production in males

Steps of hormonal control of the testes

1. GnRH from the hypothalamus stimulates the anterior pituitary

2. The anterior pituitary releases FSH and LH into systemic circulation

3. LH stimulates Leydig cells of the testes to release testosterone

4. FSH stimulates sertoli cells to increase spermatogenesis and release androgen binding protein and inhibin

5. Inhibin acts in negative feedback on the anterior pituitary to decrease the release of FSH

6. Testosterone binds ABP and exerts effects systemically that result in sex characteristics

7. Testosterone acts in negative feedback on the anterior pituitary to decrease the release of LH

Erection

Parasympathetic nervous system activation leads to increased blood flow to the penis, resulting in an erection.

Ejactulation

Sympathetic nervous system activation leads to the expulsion of semen from the male reproductive tract.

Sperm pathway

seminiferous tubule, straight tubule, rete testis, efferent ductule, head of the epididymis, body of epididymis, tail of epididymis, ductus deferens, ejactulatory duct, urethra, vaginal canal

Names the 2 structures that join to form the ejaculatory duct and describe the location of this union

The ductus deferens and seminal vesicles join to form the ejaculatory duct and this is in the prostste

pH of semen

alkaline (more basic) allows for neutralization of the acidic uterine and vaginal cavities so the sperm can survive

How long can sperm survive

2 days

Testicular torsion

This is when the spermatic cord becomes twisted. This causes the flow of substances to be prevented. Can be harmful when blood flow stops, leading to the death of the testicle

Analogous structures in the male following the females
Ovaries, Labia majora, uterine tubes, oogenesis

Ovaries= testes

Labia majora= scrotum

uterine tubes= ductus deferens

oogenesis= spermatogenesis

Function of mammary glands

is to produce and secrete milk for nursing infants.

Urethra

short tube connecting the base of the urinary bladder to the vestibule of the vagina

Cervix

feature of the uterus that opens into the vaginal canal

Ovaries

lie on the bilateral sides of the uterus within the pelvis

3 functions of the vagina

1. menstrual canal

2. sexual intercourse

3. birth canal

ovaries

site of oogenesis

uterine tube

typical site of fertilization

vagina

pathway from which any contents of the uterus exits the body

Uterus

hallow, muscular organ

endometrium of the uterus

tissue that sheds during menstruation

fundus of the uterus

area opposite the distal opening

cervix

distal opening of the uterus that extends into the vaginal canal

3 arteries that supply the uterus with blood

1. Ovarian arteries

2. Uterine arteries

3. Vaginal arteries

4 parts of uterine tube

infundibulum, fimbriae, ampulla, isthmus

4 connective tissue structures

1. broad ligament

2. mesovarium

3. ovarian ligament

4. suspensory ligament

Primary follicle

surrounded by granulosa cells; surrounds a primary oocyte

secondary follicle

contains layer of granulosa cells and zona pellucida; surrounds a secondary oocyte

tertiary follicle

last stage before ovulation occurs

Oogenesis before birth

oogonia completed mitosis resulting in the production of primary oocytes that are arrested in prophase I until puberty.

Oogenesis through puberty to menopause

Primary oocytes process through meiosis 1

folliculogenesis

development of an ovarian follicle in anticipation of ovulation

7 steps of folliculogenesis

1. Primordial follicle

2. secondary follicle

3. vesicular follicle

4. reptured follicle

5. corpus luteum

6. corpus albicans

Stages of the ovarian cycle

1. Follicular phase: period between menstruation and ovulation

2. Ovulation: LH surge results in ovulation of a follicle

3. Luteal phase: period from after ovulation to the onset of menstruation

Hormones of ovulation

Puberty marks the onset of the release of GnRH from the hypothalamus

FSH and LH stimulate ovarian follicle development and trigger ovulation.

Inhibin acts in negative feedback to prevent the release of FSH and LH

Relaxin acts on connective tissue in the uterus and pubic symphysis to prepare the body for the growing uterus

Progesterone

produced and secreted by the corpus luteum after ovulation

LH

stimulates ovulation of the matured secondary oocyte

FSH

stimulates the maturation/development of an ovulated follicle

hCG

produced by the placenta; stimulates the corpus luteum to release progesterone to maintain the pregnancy

Menstrual through follicular phase

approximately 1-10 days of menstrual cycle

Pre-ovulatory through luteal phase

approximately 11-24 days of the menstrual cycle

Endometriosis

a condition in which endometrial tissue that typically lines the uterus grows outside of the uterus

PCOS

a condition in which the ovaries produce an abnormal amount of male sex hormones; also characterized by an increased number of cysts that form on the ovaries

Uterine cancer

malignant tumor growing within the uterus

Menses

the monthly discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina, also known as menstruation.

Menarche

onset of menses during early puberty in females

Two events that occur in response to fertilization/implantation

1. hCG secretion by the embryo that sustains the corpus luteum

2. Endometrium of the uterus thickens to support the implanted zygote

Fast black reaction

depolarization of the oocyte membrane in response to sperm dusion with the oocyte membrane

Slow block reaction

Ca2+ ions efflux from the oocyte triggers the cortical reaction

Morula

early embryo made of approximately 8-32 cells (forms 3-4 days post fertilization)

Blastocyst

early embryo that forms 5-6 days post fertilization

Trophoblast

specialized cells that form the outer layer of a blastocyst; essential for implantation & early embryonic development

ectopic pregnancy

event in which the zygote implants in a structure other than the endometrium of the uterus

embryonic phase

implantation- 8 weeks gestational age

placental phase

9 weeks gestational age- birth

key hormone during labor that is controlled via a positive feedback mechanism

Oxytocin

Name the hormone that functions the preparation for production of breast milk

Prolactin

Describe how hormones change throughout pregnancy

hCG initial spike during early pregnancy followed by sharp decline

Estrogen and progesterone begin relatively low but increase gradually over time; sustained at high levels from mid-pregnancy through birth

Process of implantation

1. blastocyst adheres to the endometrium

2. Syncytiotrophoblast burrows into the endometrium until the mebryo is buried in endometrial tissues

3. Successful implantation results in secretion of hCG

Process of fertilization

1. sperm reaches the egg, typically within the uterine tube

2. Sperm transverse the corona radiate surrounding the oocyte

3. sperm bind to the zona pellucida of the oocyte, initiating the acrosomal reaction

4. Plasma membranes of the oocyte and sperm head fuse, allowing the sperm to enter

5. The resulting zygote is now diploid with 23 paired chromosomes (46 total)