The endocrine system produces hormones that control body functions and are released by glands. The major glands include the pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries, and testes. Hormones travel through the bloodstream and bind to receptors on cells to regulate processes like metabolism, immune function, reproduction, and stress response. Endocrine disorders occur when hormone levels are too high or too low, leading to conditions such as diabetes, thyroid disorders, and reproductive issues.

1. Endocrine
• Produces chemical messages for the body
• Controls body functions with chemicals
• Chemicals are called hormones
• Location where chemicals are produced are
glands, (group of cells that make special
chemicals for the body
• Chemicals travel in the blood stream
• Operates on feedback mechanisms
• Ex: epinephrine – the fight or flight chemical
released in stressful situations

2. • Two types of hormones
• Steroid – passes directly through cell
membrane
• Binds to receptor proteins in specific cells to
form hormone receptor complex
• Enters nucleus and binds to a DNA control
sequence
• Transcription of specific genes to mRNA
• mRNA move into cytoplasm and directs protein
synthesis

3. • Nonsteroid: cannot pass through cell
membrane
• Binds to receptors on the cell membrane
• Activates enzyme on surface of cell membrane
• Enzyme activates secondary messengers that
carry hormone into cell
• cAMP, nucleotides and fatty acids can act as
secondary messengers
• Messengers can activate or inhibit cell activities

4. Glands
• Pituitary – secretes 9 hormones - (HGH)
stimulates skeletal growth, controls water levels
in blood, keeps thyroid gland functioning
properly and stimulates the process of
pregnancy
– Bean sized located in the base of the brain
• Thyroid – controls the rate of metabolism
– Located in the front of the neck, (thyroxin)
• Parathyroid – controls calcium in the blood
– Located in the neck behind the thyroid

7. • Thymus – regulates immune system to
help fight disease
• Located on top of the heart
• Adrenal – releases epinephrine and
norepinephrine that deals with stress
• Located on top of the kidneys
• Pancreas – controls blood sugar (also
part of the digestive tract

11. Endocrine disorders
• Usually caused by an imbalance (to much
or to little of a chemical)
• Insulin – controls the amount of blood
sugar in the body
• Responds when food is eaten, cells are
given instructions to take in glucose when
the blood sugar increase

12. • diabetes mellitus – conditions where the
pancreas doesn’t make enough insulin
• May require a person to take insulin shots
to help balance glucose levels
• Growth hormone – stunted growth due to
the pituitary glands failure to produce
enough growth hormone (dwarfism)

13. • Some conditions can be treated with
medication to correct if found soon
enough
• Over active pituitary glands can result in
over growth of the body (gigantism)

14. • Goiter – cause by a lack of iodine in the
diet
• Body lacks thyroxine
• Thyroxine speeds up metabolism
• Thyroxine deficient cells are less active,
can cause a body to be fatigued, weight
gain and additional problems
• Used to be called “rich mans disease”

15. Reproductive glands
• Gonads – production of gametes and
secretion of sex hormones
• Ovaries – (female) hormones for
reproduction
• Testes – (male) hormones for
reproduction

17. Reproduction
• 1st
6 weeks of development embryos are
identical in appearance
• 7th
week – primary reproductive organs
begin to develop
• Hormones released by testes
(testosterone) and ovaries (estrogen)
determine if embryo will be male or female

18. • After birth, gonads continue to produce
small amounts of sex hormones that
influence the development of reproductive
organs
• Neither the testes or ovaries can produce
active reproductive cells until puberty
• Puberty – rapid growth and sexual
maturation during which the reproductive
system becomes fully functional.

19. • Puberty varies among individuals but
usually starts between ages 9 to 15 and
starts on average 1 year earlier in females
• Hypothalamus increases production of
FSH and LH

20. Male Reproductive
• Function – produce and deliver sperm
• Primary organ is testes developed in the
abdominal cavity and will descend just
before or after birth into scrotum where
temp is about 3° lower than body temp
• Within each testis are hundreds of tubules
called seminiferous tubules where sperm
is produced (millions)

21. • Sperm moves to the epididymis where fully
mature are stored
• Sperm moves to the vas deferens extending into
the abdominal cavity and eventually merges with
the urethra
• Urethra is the tube that leads to the exterior of
the body through the penis (urine and sperm exit
body in same structure)
• Release of sperm through the penis is controlled
by the autonomic nervous system

22. Female Reproductive
• Function is to produce ova and prepare
female body for developing embryo
• Primary organ ovaries located in the pelvic
region of the abdominal cavity
• Produce one mature ovum (egg) a month
• Each ovary contains about 400,000
primary follicles, clusters of cells
surrounding a single egg

23. • Females are born with thousands of
immature eggs but only about 400 will
actually be released
• Approx. every 28 days, FSH increases
and a follicle gets larger and completes
the 1st
meiotic cell division
• When meiosis is complete, a single large
haploid egg and 3 polar bodies are
produced (where disintegrate)

24. • Egg is released in process called ovulation
• Follicle breaks open and egg enters
opening of Fallopian tube (two) and is
pushed along fluid-filled tube by cilia (egg
can be fertilized here, not good)
• After a few days, egg passes from
Fallopian tube into the uterus
• Uterus is ready to receive egg

25. • Outer part of uterus is cervix which leads
to a canal called the vagina that leads to
the outside of the body

26. • After puberty the interaction between the
reproductive and endocrine system in
females forms a complex series of events
called the menstrual cycle (continues until
mid-40’s)
• Uterus prepares for egg, if fertilized,
embryo implants and development begins
• If not, discharged with lining of uterus

27. 4 Phases
• 1) Follicular –(10 days) begins when
estrogen is low, hypothalamus stimulates
the pituitary gland to produce FSH and LH
and cause the follicle to mature
• Egg enlarges and surrounding cells
produce more estrogen and levels in
blood begin to rise causing lining of uterus
to thicken (take about 10 days)

28. • 2) Ovulation: shortest phase, (4 days),
hypothalamus sends signal releasing hormones
to tell pituitary gland to make more FSH LH and
causes the follicle to rupture and release mature
egg which is swept up into the Fallopian tube
• 3) Luteal (7days): as egg moves through
Fallopian tube, ruptured follicle turns yellow
changes to corpus luteum and begins to release
progesterone which stimulates growth and
development of blood supply and surrounding
tissue

29. • During first 2 days of luteal phase, the chances
of fertilization are the greatest (10 to 14 days
from last menstrual cycle)
• 4) Menstruation – (3 to 7 days) if fertilization
doesn’t take place, within 2 to 3 days the egg will
pass through the uterus, the corpus luteum will
disintegrate, the old follicle breaks down
producing less estrogen and progesterone and
the lining of uterus detaches from uterine wall
and all of this material is expelled out of the body
through the vagina
• Process repeats.

30. Fertilization and Development
• Fertilization: process of joining egg (haploid) and
sperm (haploid) form diploid(2N); contains a set
of chromosomes from each parent
• Fertilized egg is called zygote
• While in the Fallopian tube, the zygote
undergoes mitosis, as each cell divides the
number of cells doubles, 4 days after
fertilization, cell is a solid ball of approx. 64 cells
called a morula

31. 3 stages of early development
• Implantation: morula forms cavity in
center, forming a hollow structure with an
inner cavity called a blastocyst which in 6
to 7 days attaches to uterus
• Embryo secretes enzymes that digest a
path into the soft tissue
• Cell begins to differentiate due to gene
activation

32. • Gastrulation: formation of 3 cell layers,
ectoderm, mesoderm, endoderm called
primary germ layers: all organs and
tissues will developed from them
• Endoderm – digestive system
• Ectoderm – skin and nervous system
• Mesoderm – internal tissues and organs
• Neurulation: development of the nervous
system

33. • Extraembryonic membranes: amnion and
chorion
• Amniotic sac: fluid filled sac which
cushions and protects embryo
• Chorion: 3rd
week of development –
outermost membrane
• chorionic villi form on outer surface and
extend to uterine lining

34. • Resulting membrane is the placenta –
connection between mother and embryo and
performs respiration, nourishment and excretion
• At 8 weeks of development embryo is called a
fetus
• Stem cells – unspecialized, undifferentiated cells
found in fetal tissue and bone marrow and
brains of adults

35. Development
• At 3 months, most major organs and
tissues are fully formed, umbilical cord
connects fetus to placenta and fetus is 8
cm long and a mass of 28 grams
• 4th
5th
6th
months, tissues become more
complex and specialized and more tissues
begin to function; heart becomes audible,
bones begin changing, hair grows on skin,
movement

36. • Last 3 months, organ systems mature and
fetus grows in size and mass
• Lungs and other organs undergo series of
changes to prepare of life outside the
uterus
• Babies born before 8 months are
premature and have breathing problems
and CNS problems

37. • At 9 months oxytocin is released from
pituitary gland that will begin contractions
of large involuntary muscles in uterine wall
• As contraction become more frequent and
stronger, cervix expands, amniotic sac
breaks and is released
• Born head first, baby will cough/cry to
remove fluid from lungs, umbilical cord is
cut (navel)

38. • Infancy – 1st 2 years of life, rapid growth,
teeth appear, language is imitated and
understood
• Childhood: 2 years to 13, motor
coordination, permanent teeth, long bones
of skeletal system reach 80% of adult
length, personality, social skills, reasoning

39. • Adolescence: puberty to adulthood, sex
hormones start puberty that produces
growth spurt that will slow in mid-
adolescences as long bones stop growing
and ossification takes place, higher
thinking skills develop and personality
changes, brain fully develops around age
20

40. Diseases
• Bacterial infections: Chlamydia, syphilis
(fatal), gonorrhea (treatment, antibiotics)
• Viruses: hepatitis B, HIV, HPV, genital
herpes (no cure)

41. Multiple Births
• Two eggs released and both are fertilized
by different sperm, fraternal twins are born
• Single zygote splits apart producing
identical embryo’s, always the same sex