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
together
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-
fast.
Onset of hormone release
Could be immediate or take several days
Released inactive in some hormones until something activates it, ex. Blood
Chemistry
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
ADH
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
Follicles
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
Testes
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
happens
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
Penis
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
Urethra
Regions:
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
ejaculation
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
Semen
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
Ejaculation
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
Spermatogenesis
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
chromosomes.
Meiosis
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-spermatocyte=spermatid
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
Effects:
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
Gonads
Ovaries 2 roles
Gametes and hormones
Ligaments
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
Internal
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.
External
Visceral peritoneum supported by mesosalpinx-(salpin=trumpet) part of broad
ligament
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
Uterus
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-
Adventitia-fibroelastic
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
exam.
Vaginal fornix-vaginal recess at upper end of vaginal canal loosely surrounded by
cervix
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
Glans
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
anus
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
lobes
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
Puberty
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
Ovulation
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
Cycle:
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
Out.
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
Estrogen
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.