Endocrine System

Key Concepts


Function-To coordinate and integrate the activities of cells in the body.

Endocrine vs. Exocrine

            Exocrine-non-hormonal, sweat and salivary, has ducts

            Endocrine-empty hormones into blood or lymph, no ducts

Hormones-chemicals that travel long distances and secreted into extra-cellular fluid. 

            They regulate the metabolism of other cells

Types of hormones

            Usually amino acid based-water soluble

            Peptide-ADH-lipid soluble, made from cholesterol, steroids, need a messenger

              to cross the cell membrane

            Fats-eicosanoids-blood clotting, inflammation, uterine contraction, leukotrine,

Target cells-cell hormone is targeting or sending signal to.  If cell has receptor for

            Hormone A, it is a target for hormone A.  Steroids receptors (target) is inside

              Cell, amino acid, receptor on surface of cell outside

Mechanisms or effects of hormones

1)     to open or close ion channels

2)     stimulate protein synthesis

3)     activate or deactivate enzyme

4)     induce secretion

5)     stimulate mitosis

Types of mechanisms

            Cyclic AMP (cAMP)-2nd messenger-1st messenger is hormone, hormone binds

              to surface molecule, needs ATP and changes surface molecule to create cAMP,

              starts a chemical cascade and makes protein kinase

            PIP calcium-2nd messenger system, uses calcium for second messenger

            cAMP phoosphodiesterase- enzyme that deletes cAMP finds it and gets rid of it

Up and down regulation

            Up regulation-hormone tells cell to make more receptors for hormone

            Down regulation-doesn’t make receptors

Half-life onset and duration of hormone activity

            Steroids and thyroid hormone use carrier proteins to get around the body, travel


            Amino acid based hormones float free

            ˝ life-length of time a hormone remains in the blood. Typical ˝ life-less than

              1 minute to 30 minutes.  Steroids-hours to days before effect. Water soluble-


Onset of hormone release

            Could be immediate or take several days

            Released inactive in some hormones until something activates it, ex. Blood


            3 ways hormones interact

1)     permissiveness-hormone A makes it possible for hormone B to work

2)     synergism-working together-hormones A and B have same effect on target but more so if both are there

3)     antagonism-work against-hormone A and B have opposite effects

Control of hormone release

            Negative feed back-as hormone levels rise the cause target organ to inhibit further

              Hormone release. 

            Three kinds of stimuli:

              1)Humoral-chemestry of body fluids change

              2)Neural stimuli-nerve fibers stimulate hormone release. Nerves can tell

                   endocrine organ to release hormone

              3)Hormonal- one hormone can tell gland to release another hormone, controlled

                    by hypothalamus and pituitary

Pituitary and hypothalamus ( hypophysis)

            3 parts

1)     infundibulum-stalk-made of nerves

2)     neurohypophysis-posterior-stores and releases hormones

3)     adenohypophysis- anterior-modified oral mucosa

neurohormones-made by axons starting in the hypothalamus and ending at

  posterior pituitary

posterior lobe-part of the brain (extension of the hypothalamus), holds oxytoxin


            Anterior lobe-epithelial tissue-venous connection to hypothalamus and posterior

              pituitary, regulated by nerohormones of hypothalamus

            Tropic hormones affect other glands

Pituitary hormones: summary of regulation and effects

            Amino acid hormones:

            Antidiuretic hormone-ADH-post. Pit.-stops water loss

            Growth hormone-GH-ant. pit.-stimulates growth

            Adrenocorticotropic hormone-ACTH-ant. pit.-stimulates adrenal

            Gonadotropins-follicle-stimulating hormone-FSH and Luteinizing hormone-LH-

              Targets gonads

            Prolactin-PRL-ant.pit.-promotes lactation

            Oxytocin-post.pit.-arousal and orgasm-cuddle hormone

            Thyroid stimulating hormone-TSH-ant. pit.-stimulates thyroid

            Follicle stimulating hormone-FSH-ant.pit-women,makes hormones and stimulates


            Luteinizing hormone-LH-ant. pit-gamete production

            Aldosterone-increases reabsorption of sodium-less peeing

Thyroid gland

            Follicles-hollow chambers filled with colloid-stuff to make hormones

              Tyrosine and iodine mostly

            Follicles-walls made of follicular cells pump iodine into colloid, use the colloid

              To make TH (thyroid hormone)

            Parafollicular cells-make calcitonin-take calcium from blood goes to bone

            Thyroid hormone-made of 2 hormones T3 and T4

            T3-triiodothyronine-3 amino acids

            T4-thyroxine-4 amino acids

            Thyroid hormone-metabolism increase, maintain blood pressure and regulate

              Growth and development

Synthesis 6 steps

1)     follicle cells make thyroglobin

2)     collect iodine from blood 30 times blood level

3)     hook iodine to thyrosin

4)     enzymes hook thyrosines together

5)     take colloid of lumen of follicle w/lysosome

6)     release hormone

Parathyroid gland

            Next to thyroid-makes parathyroid hormone (PTH)-protein hormone-controls

              calcium balance in blood. Causes osteoclasts to break down bone and send

              calcium to blood.  Tells kidney to activate vitamin D, let us absorb calcium

              from food.

Adrenal gland (Lab stuff, picture on pg.625)

            Cortex-outer layer-zona glomerulosa-aldosterone-mineral corticoids-mineral

              water balance

            Zona fasciculata-glucorcorticoids-metabolic hormones that use sugar

            Zona reticularis-next to medulla-has fibers-look for spaces between fibers

              darker stain

 Function of renin-angiotension mechanism

            raise blood pressure-keep fluid in and cause vasoconstriction

            Atrial natriuretic peptide (ANP)-lower blood pressure, makes you urinate more

              How? Blocks angiotension mechanism, less Aldosterone

Glucocorticoids-cortisol-ACTH goes up, cortisol goes up, stimulated by ACTH.  Help

            Us resist stressors, steroid hormone

Gonadocorticoids (sex hormones)-mostly andogens (male hormones) raw stuff to make

            estrogen and testosterone

Adrenal medulla-makes epinephrine 80%  and norepinephrine 20%.  Same effects

            Chromaffin cells-modified neural cells in medulla responsible for epinephrine

              and norepinephrine

Notes ended refer to your notes from class
















Reproductive System


Primary sex organs

            Gonads-testes in males and ovaries in females. 

              Gametes- eggs and sperm

              Accessory reproductive organs-remaining reproductive structures-ducts, glands,

                 external genitalia





Male anatomy

            Scrotum-sac containing testes

            Septum-wall separating

            Muscles-keep temp constant

            Cremaster muscle-inside spermatic chord.  When contracts, scrotum goes towards

              The body, keeps warmer

            Dartos muscle-inside lining the skin of the scrotum.  When contraction occurs

              It wrinkles skin or wrinkles, reduces heat loss







            Tunica vaginalis-outer serous layer-2 sides from peritoneum

            Tunica albuginea-fibrous capsule of testes-outside of testes

            Lobule=1 to 4seminiferous tubules (anterior side) where spermatogenesis


            One tubulus rectus-short and straight

            Rete testis-posterior side, sperm leave the testis through the efferent ductules

              and enter the epididymis which hugs the external testis surface

            Interstitial cells (Leydig cells)-between seminiferous tubules-produce androgens,

              the male sex hormone, testosterone    

            Testicular artery branches off abdominal aorta

            Testicular veins draining the testes arise from the pampiniform plexus which

              surrounds the testicular artery.

            Muscles-Dartos-wrinkles scrotum and Cremaster raises muscle for warmth








            Consists of an attached root and a free shaft or body that ends in an enlarged tip

               The glans penis

            The Corpus spongiosum surrounds the urethra

            Corpora cavernosa are a paired dorsal erectile body







The duct system

            Epididymis-posterior side of testes-phagocized by epithelial cells of smooth

               muscle wall

            Takes 20 days for immature sperm that leave the testes to travel from the head to

              tail, they mature as they move through

            No motile microvilli absorb testicular fluid and pass nutrients to sperm in lumen

            Sperm can live several months there







Ejaculatory duct

            Vas deferens runs upward as a part of the spermatic cord through the inguinal

              canal into the pelvic cavity.

            Lies posterior side over the bladder, it expands to form the ampulla, joins with

              Seminal vesicle to form the ejaculatory duct which enter the prostate gland

              And empties into the urethra






              Prostatic (prostate)

              Membranous urethra (body wall)

              Spongy urethra (penis, corpus spongiosum

              External urethral orifice

              external urethral sphincter







Accessory glands

            Seminal vesicles-two-60% of semen volume-alkaline, neutralize acid in vagina

              fructose-energy for sperm



            Bolbourethral glands-two (cowper’s glands)-below prostate, embedded in wall

              of pelvis, thick alkaline mucous, neutralizes urine acidity in urethra before




            Prostate-one-below bladder around urethra-chemicals to activate sperm

              Citrate, enzymes, prostate specific antigen

              20-30 glands in smooth muscle, thick connective tissue capsule







            White, sticky

            Mixture of sperm and fluid

              Transport sperm-ejaculation

              Nourish sperm-seminal vessel

              Protect sperm-bulbourethric and seminal

              Activate sperm-prostate






Male sexual response

            Erection-penis gets big and stiff

            Parasympathetic nervous system triggers nitric oxide locally, nitric oxide

              vasodialtes arterioles

            corpora cavernosa and spongiosum expands and fills with blood with pinches

              veins, slows drainage and keeps erection








            Sperm stored in ducts leaves body

              Sympathetic system kicks in

1)     close internal urethral sphincter

2)     contraction: contents to urethra

3)     bulbospongiosus muscles undergo a rapid series of contractions






            Sperm formation

            Having two sets of chromosomes, one from each parent, the normal number of

              Chromosomes is referred to as the diploid chromosomal number, in humans it is

              46and diploid cells contain 23 pairs of chromosomes called homologous






            Two parts

            Meiosis I

1)     cells replicate DNA

2)     synapses-little groups of four chromatids called tetrads are formed.  During

synapses crossovers occur

3)     divide-normal amount of DNA (n) ˝ normal number of genes

Meiosis II

  Just like meiosis but without replication (n) ˝ normal number of genes






Summary of events in seminiferous tubules

            Mitosis of spermatogonia (2n) (sperm making cells

              (2n) type A-replace spermatogonia parent

                      type B-primary spermatocyte


                        Meiosis I-synapsis-tetrids and crossovers

                                         Divide into secondary spermatocyte

                        Meiosis II-each secondary spermatocyte divide into 4 spermatid












Spermiogenesis – spermatids to sperm         

            Spermatid-immobile, round and no tail

            Mature sperm- head, acrosomal process, midsection and tail





Sustentacular cells (Sertoli cells)

            Tall cells lining the seminiferous tubule wall, tight junctions with blood barrier

               Surround developing sperm cell

            Nutrients, testicular fluid, chemicals mediating spermatogenesis




Hormonal regulation of activity

1)     gonadotropin releasing hormone from hypothalamus

2)     anterior pituitary prompts GnRH to secrete FSH and LH to blood

3)     FSH stimulates spermatogenesis indirectly by stimulating Sustentacular cells

To release androgen-binding protein (ABP).  ABP prompts the spermatogenic

Cells  to bind and concentrate testosterone

4)     LH binds to interstitial cells getting them to secrete testosterone

5)     Feedback testosterone goes up GnRH goes down from hypothalamus,

Gonadotropins goes down, anterior pituitary.  Sustentacular cells-sperm count up, inhibition up, FSH and GnRH down






Testosterone mechanism and its effects

            Testosterone=steroid hormone is synthesized from cholesterol. Wants to bind at

              The nucleus



                        1)  spermatogenesis

2)     anabolic effects, growth development, male and female repro. Organs

lack of; sterile or impotent

3)     secondary sexual effects- pubic hair, deeper voice, denser bones, sex

drive up.







Female reproductive anatomy

            More complex, more roles, make gametes and nourish developing fetus


            Ovaries 2 roles

              Gametes and hormones



            Ovarian ligament-ovary to uterus

            Suspensory ligament-ovary lateral to pelvic wall

            Mesovarium-fallopian tube and uterus



Ovarian Arteries

            Branch off abdominal aorta

            Tunica albuginea-fibrous white coat over ovary

            Germinal epithelium-cuboidal epithelium-part of peritoneum

            Medulla-blood and nerves

            Cortex-gameteogenesis-sack like structures called follicles.  Each follicle

               contains one immature egg (oocyte).  Surrounding cells are follicle cells-one

               layer and granulose cells when more than one layer is present

               Primordial follicle-one layer of squamous like follicle cells surround oocyte.

               Primary follicle-two or more  layers of cuboidal granulose cell surround oocyte

               Antrum-fluid space between layers of cells

               Vesicular follicle (Graafian follicle)-follicle bulges from surface of ovary

               Ovulation-rupture of follicle

               Corpus liteum-glandular structure-some estrogen-progesterone






Female duct system


            Fallopian tubes-narrow at uterus-as narrow as a human hair-provide a site where

               fertilization can occur.

            Ampulla-wide area-fertilization usually occurs here

            Infundibulum-open funnel shaped structure bearing ciliated finger like projections

              called fimbriae that drape  over the ovary. No connection to ovaries-current to

              draw egg in tube-smooth muscle-mucosa-both ciliated and none folded-

              peristalsis-towards uterus.


            Visceral peritoneum supported by mesosalpinx-(salpin=trumpet) part of broad






Homeostatic imbalance

            Ectopic pregnancy-egg doesn’t implant in uterus-usually means fetus grows in

              fallopian tube.  These pregnancies usually naturally abort with major bleeding

            Pelvic inflammatory disease (PID)-STD microbes from reproductive tract infect

              peritoneal cavity




            Anterior to rectum and superior to bladder

            Anteverted- inclined forward

            Cervical glands-mucosa of cervical canal-thick mucosa fills canal and covers

              opening.  It is less thick in mid-cycle and allows sperm to pass through.  Also

              blocks spread of bacteria to uterus and blocks sperm




Supports of uterus

            Mesometrium-portion of the broad ligament

            Lateral cervical ligament-uterus to lateral body wall

            Round ligament-near dundus/isthmsus through inguinal canals, ties to anterior

              wall of body

            Uterosacral-uterus to sacrum

            Porlapse of the uterus-torn muscles during childbirth.  Unsupported uterus sinks

              inferiorly until the cervix protrudes through external vagina opening




Uterine Wall

            Perimentrium-outermost serous layer-visceral peritoneum

            Myometrium-bulky middle layer-smooth muscle-thick layer-contractions at birth

Endometrium-mucosal lining of uterine cavity-simple columnar epithelium.

      2 chief strata layers 1)stratum functionalis-changes hormone levels, thickens

            and sheds at period time.

            2) stratum basalis-base layer-forms a new functionalis after period






Vascular supply

            Uterine arteries branch from internal iliac in pelvis and ascend along the side of

              the uterus

            Arcuate arteries branches in metrium

            Radial arteries turn and give off straight arteries (stratum basalis) and spiral

              arteries (stratum functionalis)





Vagina (Birth canal)

            Thin wall, 8-10 cm. Long.  Between the bladder and rectum.  Wall is stretchy

              for baby to pass through

            Layers outside-


                        Muscularis-smooth muscle

                        Mucosa-rugae (ridges) stimulate the penis.  Epithelial cells of mucosa

                           Release glycogen metabolized to lactic acid by bacteria, makes it acidic

                           Aids in keeping other bacteria out

              Vaginal orifice opening to vagina, makes incomplete partition called the hymen.

               Hymen is very vascular and bleed if ruptured b sex, sports, tampons and pelvic


            Vaginal fornix-vaginal recess at upper end of vaginal canal loosely surrounded by






External genitalia

            Vulva-mons puis, labia, clitoris and vestibule

            Mons pubis-fatty mound- where pubic hair grows

            Labia majora-skin, thin and hairless-surround space “vestibule”

            Vestibular glands-release mucus into the vestibule for lubrication

            Clitoris-erectile tissue that is homologous to the penis-exposed part called the


            Prepuce-hood of clitoris

            Perineum-diamond shaped-located between pubic arch anteriorly and the coccyx

               posterior, and the ischial tuberoses laterally.  Space surrounds vestibule and






Mammary glands (breasts)

            Modified sweat glands

            Nipple-smooth muscle-erect if stimulated, cold, autonomic nervous system

            Areola-ring of pigmented skin

            Sebaceous gland-oil gland, no chapping or cracking






Internal anatomy

            15-25 lobes radiate around nipple

            Suspensory ligaments-interlobar connective tissue


                        lobules-contain glandular alveoli that produce milk

                        lactiferous ducts-open to outside at nipple

                        lactiferous sinus-where milk accumulates during nursing




Breast cancer

            Usually epithelial cells of lactiferous ducts

            Risks-early puberty, menstruation or in late menopause

                        1)  late pregnancy

2)     no pregnancy, no early pregnancy

3)     previous breast cancer

4)     family history

changes- skin texture, puckering, leaking

self exam-most common detection

mammography- should have at 40 then each 2 years






 Female physiology

            Oogenesis-making eggs

            Before birth-mitosis of oogonia (2n), enter a growth phase.  Primordial follicles

              Begin to appear as oogonia are transformed into primary oocyte, they become

              Surrounded by flattened follicle cells






            400,000 oocyte remain, only a small number of primary oocyte are activated

               each month, only one is selected each time to continue meiosis I producing

               two haploid cells.  The smaller cell is the first polar body.  The larger cell

               contains nearly all of the cytoplasm of the primary oocyte.  The second oocyte

               is released at ovulation, if fertilized it finished meiosis and yields one ovum






Ovarian cycles

            Primordial follicle are activated, directed by oocyte, the squamous like cells

               Surrounding the primary oocyte grow becoming cuboidal cells, the oocyte

               Enlarges, the follicle is now a primary follicle.

2)     They then multiply and make layers called granulose cells, they are connected

Are connected by gap junctions.  Chemicals from the granulose cells tell

The oocyte to grow

3)     A layer of connective tissue condenses around the follicle forming the

Theca folliculi (box around the follicle), makes androgens which the

Granulose cells convert to estrogen.  At the same time the cells produce a

Glycoprotein rich substance that forms a thick transparent membrane called

The zona pellcida around the oocyte.

4)     granulose cells form a fluid filled cavity called the Antrum




Secondary follicle becomes a vesicular follicle

            Antrum continues to expand with fluid until it isolates the oocyte along with

               The surrounding capsule of granulosa cells called a corona radiata.  Mound

               Of granulosa cell it sits on is cumulus oophorus






            Follicle at ovary wall ruptures and spills oocyte out into peritoneal cavity





Luteal phase

            Antrum fill with blood, corpus hemorrhagicum is  reabsorbed

            Granulosa  and theca cell form a new endocrine gland the corpus luteum

              Where estrogen and progesterone are made

            Degenerates in 10 days if no pregnancy, at this phase it is a scar called the

              Corpus albicans (white body)





Ovarian cycle

            More complicated hormones more complicated repro. System

            Childhood-growing ovaries: estrogen.  Suppresses GnRH in hypothalamus

            Puberty-hypothalamus less sensitive to estrogen releases GnRH and the pituitary

               Releases FSH and LH


            Levels increase up to 4 years until adult cycle

            The first menstrual cycle is referred to as menarche (first month)





Events 1-8 in ovarian cycle

1)     hypothalamus releases GnRH and the pituitary releases FSH and LH

2)     FSH and LH affect ovaries, follicle grows and matures and makes estrogen

             FSH exerts is effects on follicle cells and LH targets thecal cells

3)     Negative feedback on anterior pituitary inhibiting release of FSH and LH

While getting them to synthesize them.  Inhibin released by granulosa cells also exerts negative feedback on FSH

4)     estrogen levels are high has opposite effect it exerts positive feedback on

brain and pituitary

5)     High estrogen levels set a cascade of events into motion.  LH and some FSH

Are busted out, this is mid-cycle 14 days

6)     LH surge stimulates the primary oocyte of the dominant follicle to complete

Meiosis I, forming a secondary oocyte that continues on to meiosis II, then

Stops at metaphase II.  Also triggers ovulation around day 14, follicle thins and bursts.  After ovulation estrogen is down

7)     LH goes up and the ruptured follicle into a corpus luteum, the new gland

Starts producing estrogen and progesterone

8)     Rising progesterone and estrogen exert negative feedback on ant. Pituitary

Release of LH and FSH

            End of cycle LH falls and Luteal activity is down, corpus luteum degrades and

              Ovarian hormones drop







Uterine Menstrual cycle

            Ready for implantation 7 days after ovulation


1)     days 1-5- menstrual phase- 3-5 days of bleeding-shedding of

stratum functionalis.  Ovarian hormones at lowest level, gonadotropin beginning to rise, at day 5 estrogen levels up

2)     days 6-14- proliferative phase-basal builds new functional caused

caused by estrogen levels going up, progesterone receptors produced, and cervical mucous thins and crystallizes

3)     days 15-28-secretory phase-progesterone up from corpus luteum

which act on the estrogen-primed endometrium causing the spiral arteries to elaborate and converting the functional layer to a secreory mucosa.  The glands release glycogen used by the embryo before implanting

            End of secretory phase-progesterone is up, mucous plug thickens to keep bacteria


            No fertilization-LH goes down, corpus luteum degenerates, progesterone goes

               Down and spiral arteries kink-no oxygen-lysozymes burst and functional layer

               Destroys itself.  Spiral arteries unkink.  Blood rushing in breaks capillaries and

               Layer sloughs off





Extra uterine effects of estrogen and progesterone


1)     Oogenesis and follicle growth

2)     Anabolic effects on female repro. Tract

3)     Rapid growth in puberty, long bones

4)     Secondary sexual traits, breasts, hips, widening of pelvic bones

5)     Metabolic changes, cholesterol down, calcium uptake up





Sexual response

            Similar to males

            Arousal-blood fills clitoris, vaginal mucosa and breasts stimulated

            Autonomic nervous system makes nipples to be erect

            Vestibular glands (like a bulb) lubricate vestibule

            Same ANS pathways as men: arousal, orgasm, muscle tension up, pulse and

               Blood pressure up, uterine contractions.  No refractory period=multiple orgasm.