ENDOCRINE SYSTEM
Chapter 18
All cells in your body respond to messages sent by three major
systems:
• Nervous
• Immune
• Endocrine
All three systems works closely to coordinate the functions of your
body
Endocrine System helps to regulate growth and developmentmaking it relevant to you.
Endocrine System
Consists of a network of glands located throughout the
body
Endocrine Glands- ductless, or tubeless organs or groups
of cells that secrete hormones directly into the bloodstream
Hormones- chemical substances that are produced in
glands and help regulate many body functions
Glands secrete hormones, and then hormones are
carried to specific locations through blood stream
Hormones deliver messages to cells, which
influence mental and physical responses
• Hormones released during puberty elicit physical
responses
Pituitary Gland
Pituitary Gland- regulates and controls the activities of all
the other endocrine glands
- Known as the “master gland”
Has 3 sections, referred to as lobes
- Anterior
- Intermediate
- Posterior
About 1 cm in diameter
Anterior Lobe (front)
Produces 6 hormones
- Somatotropic (growth) hormone stimulates normal body growth and
development
- Thyroid-stimulating hormone (TSH) stimulates thyroid gland to
produce other hormones
- Adrenocorticotropic hormone (ACTH) stimulates adrenal glands to
produce hormones
Anterior Lobe (front)
- Pituitary Gland also secretes two hormones that are critical during
teenage years…. Follicle-stimulating hormone and luteinizing
hormone
- Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
control growth, development, and functions of the gonads
- Gonads- another name for testes and ovaries
- In females,
- FSH stimulates the production of estrogen the sex hormone that triggers the
development of ova
- LH is responsible for ovulation and production of progesterone
- Prolactin stimulates milk production in females who have given birth
- In males,
- LH stimulates testes to produce testosterone
- FSH controls sperm production
Intermediate Lobe (middle)
Secretes melanocyte-stimulating hormone (MSH) which
controls the darkening of the skin by stimulating skin
pigments
This is released when you go tanning
Posterior Lobe (rear)
Secretes antidiuretic hormone (ADH) which regulates
balance of water in the body
Secretes oxytocin which stimulates uterine contractions
during childbirth
Thyroid Gland
Small gland located in your neck
Produces hormones that regulate metabolism, body heat,
and bone growth.
Secretes thyroxine, which regulates the way cells release
energy from nutrients
Several disorders can result from overactive/underactive
thyroid
Thyroid
• Thyroid hormones affect
rate of metabolism
• Too little results in low
metabolism which might
make you feel cold and
tired
• Too much results in high
metabolism which might
make you nervous and
warm
Parathryoid Glands
Produce a hormone that regulates the body’s calcium and
phosphorus balance
Necessary for proper bone development
Located in the neck next to thryoid gland
Made up of four very small glands
If too little calcium in diet, parathyroid gland will take
calcium from bones to aid in nerve conduction and muscle
contraction
Hypothalamus
Links the endocrine system with the nervous system
Stimulates the pituitary gland to secrete or stop secreting
hormones
Secretes hormone-releasing hormones
Located in the brain, just above pituitary gland
Pineal Gland
Secretes melatonin, which regulates sleep cycles and is
thought to affect the onset of puberty
Scientists are still learning how the pineal gland works
Located deep in your head
Thymus Gland
Regulates the development of the immune system
- specifically the lymphoid system
Mainly active during childhood
After puberty, begins to turn into fat
Located in middle upper part of your chest
Pancreas
Gland that serves both the digestive and endocrine
systems
Secretes two hormones that regulate the level of blood
sugar:
glucagon> tells liver to release glucose
insulin> helps glucose move from
blood to cells for energy
Located mid torso behind stomach
Adrenal Glands
Adrenal Glands- two glands that help the body recover from
stress and respond to emergencies
Has 2 parts:
-Adrenal Cortex
-Adrenal Medulla
Cortex = Outer portion
Located in torso above kidneys
Medulla= inner portion
• Adrenal cortex secretes hormones that:
• aid in metabolism of fats, proteins, and carbohydrates
• help control blood sugar
• respond to stressors
• control blood volume and pressure
• inhibits amount of sodium excreted in urine
• produces some sex hormones that are important in secondary sex
characteristics
• Adrenal Medulla is controlled by the hypothalamus and
autonomic nervous system
• Produces epinephrine (adrenaline) and norepinephrine
• Epinephrine increases:
• heart rate
• Opens airways to improve oxygen intake
• Increases blood flow to muscles
• suppresses the digestive system during times of high emotion
• Norepinephrine relates to maintain normal body activity rather than
emergency situations
Problems of the Endocrine System
• Type 1 Diabetes
• Pancreas produces too little or no insulin, resulting in high blood
glucose levels.
• Symptoms include fatigue, weight loss, thirst and frequent urination
• People with Type 1 Diabetes take insulin to maintain appropriate
insulin levels
• Type 2 Diabetes
• Body resistant to the insulin in blood. Can be treated with
medication, diet and exercise.
Problems of the Endocrine System
• Grave’s Disease (Hyperthyroidism)
• Overactive and enlarged thyroid gland produces excessive thyroxine
• Symptoms include anxiety, weight loss, rapid heartbeat, and intolerance for
heat
• Swelling behind the eyes causes them to bulge
• Goiter
• Enlargement of the thyroid gland, can be caused by lack of iodine in diet
• Goiters are rare, due to iodized salt in US
• Hypothyroidism = low thyroxine production
• Causes fatigue, dry skin, weight gain, constipation and sensitivity to cold
• In children, leads to slow growth rates
Problems of the Endocrine System
• Cushing’s Disease
• Overproduction of adrenal hormones
• Symptoms include round face, humped upper back, thin and easily
bruised skin, and fragile bones.
• Growth Disorder
• Abnormal amounts of growth
hormone
• Can lead to gigantism or dwarfism or
Acromegaly (very rare) >>>
Grave’s Disease
Goiters
Cushing’s Disease
Male Reproductive System
Male Reproductive System
• Consists of internal and external organs
• Two main functions include:
• Production and storage of sperm
• Transfer of sperm to female during intercourse
• Sperm- the male reproductive cells
• Male reproductive system usually reaches maturity
around ages 12-15
Male Reproductive System
• When maturity is reached, pituitary gland begins
production of testosterone
• Testosterone is the male sex hormone
• Testosterone initiates physical changes such as
broadening of shoulders, muscle development, body hair,
deepening of voice
• Also controls sperm production
• Mature males are capable of producing sperm for the rest of their
life
External Male Reproductive Organs
• There are two external organs:
• Penis
• Scrotum
• Penis- Tube shaped organ that extends from the body,
just above the testicles
• Scrotum- external sac of skin that houses the testes
External Male Reproductive Organs
• At birth, males have a covering of loose thin skin over the
tip of the penis called a foreskin
• Some parents choose to have the foreskin removed in a
process called circumcision
• This procedure if often completed for cultural or religious purposes
• Circumcision is not considered medically necessary
External Male Reproductive Organs
Fertilization
• Sperm are produced and stored in testes
• Sperm cannot live in temperatures exceeding 98.6˚F
• When body temperature is too high, testes are lowered
• When body temperature is too low, testes move closer to body
• Ideal temperature is about 93˚F
• Sperm are secreted from the penis with a fluid called
semen
• Semen- is a thick fluid containing sperm and other
secretions from the male reproductive system
Fertilization
• The penis is composed of spongy tissue with many blood
vessels
• When aroused, the tissue becomes engorged with blood
and the penis becomes enlarged and erect
• During the height of sexual arousal, a series of muscular
contractions occurs, resulting in ejaculation, the release of
sperm and semen from the penis
• Ejaculation may result in the joining of a sperm cell and
female egg
Fertilization
• When sperm production begins, a male may experience a
nocturnal emission
• During a nocturnal emission, sperm and semen are
ejaculated while a male is asleep
• This happens to release pressure as sperm build up begins
• This is a normal body function
Male Internal Reproductive Organs
• Internal Reproductive Organs include:
• Testes- Two small glands located in the scrotum that produce sperm
• Epididymis
• Location where sperm are stored and matured
• Vas Deferens
• 2 long thin tubes sperm travel through
• Urethra
• Passageway for semen and urine to exit body
• Seminal Vesicles
• Secrete fluids that make up semen
• Prostate Gland
• Secrete fluids that make up semen, adding to a more livable environment for sperm
• Cowper’s Gland
• Secretions and lubrication of fluid into urethra
Care for Male Reproductive System
• Regular check-ups
• Bathe regularly
• Especially those who are uncircumcised, paying special attention to
foreskin
• Wear protective equipment when necessary
• Perform regular self-exams
• Checking for signs of cancer
Sexually Transmitted Diseases
• Chlamydia
• A bacterial infection that can cause a discharge from the penis and
burning sensations during urination.
• Can cause reproductive damage
• Gonorrhea
• Similar results to Chlamydia
• Syphilis
• Bacterial infection, marked by a painless red sore near site of infection
• Can spread and damage internal organs
• Genital Herpes
• Virus causing periodic blisters in the genital area
• Medications can relieve symptoms, but virus remains for life
Problems of Male Reproductive System
• Inguinal Hernia
• Inguinal canal doesn’t completely close leading to weak spot
• Separation of tissue leading to an abnormal lump in groin area
• Lump is intestine
• Requires surgery to repair
• Sterility- inability to reproduce
• Can result from having 20 million or fewer sperm per millimeter of
seminal fluid
• Results from radiation, chemical imbalances, medications, or STDs
Problems of Male Reproductive System
• Testicular Cancer
• Occurs most frequently in 15-40 year olds
• It is important to perform a self exam on a monthly basis
• With early detection, most testicular cancer is treatable
• Prostate Cancer
• 2nd most common type of cancer in American men
• Males should be screened regularly once they hit 50, unless high risk
• Very treatable if detected early
• PSA test
• Benign Prostate Hypertrophy (BPH)
• Enlarged prostate, occurs in almost all men 60+
• Prostate can become enlarged and presses against urethra causing frequent
urination
Female Reproductive System
Female Reproductive System
Endometrium
Female Reproductive System
• Female Reproductive System has two functions:
• Produce female sex hormones
• Store female reproductive – ova
• Female Reproductive System includes several organs/glands
• Ovaries
• Fallopian Tubes
• Uterus
• Cervix
• Vagina
Female Reproductive System
• Fallopian Tubes- pair of tubes with fingerlike projections
that draw in the ovum
• Cilia are hairlike projections on end of tubes to attract ovum
• Uterus- hollow, muscular, pear-shaped organ inside a
female’s body
• Protects and nourishes the fertilized ovum from conception until birth
• Vagina- Muscular, elastic passageway that extends from
the uterus to the outside of the body
• Cervix- Lower end of uterus that connects to vagina
Female Reproductive System
• Ovaries- female sex glands that store the ova and produce
female sex hormones
• At birth, females have roughly 400,000 ova (eggs)
• By puberty only around 400 remain and mature enough for fertilization
• Ovulation- the process of releasing a mature ovum into the
fallopian tube each month
• Alternates ovaries each month (right/left)
Menstruation
• Each month the female reproductive system prepares for
pregnancy
• If pregnancy doesn’t occur, the lining of the uterus,
endometrium, breaks down into blood and tissue and is
shed
• Menstruation- the shedding of the uterine lining
• After 5-7 days the menstrual cycle begins again
• When cycle first begins, it may be irregular
• After time, each females cycle will become more predictable
Menstrual Cycle
Days 1-13
New egg matures in ovary
Day 14
Mature egg is released into
fallopian tube
Days 15-20
Egg travels to uterus
Days 21-28
After 7 days if egg is not
fertilized, menstruation
begins
Care of the Female Reproductive System
• Bathe regularly
• Abstaining from high risk behavior
• Only 100% guarantee
• Breast Exams
• Check for abnormal lumps or growths on regular basis
• Breast cancer is most common cancer and 2nd leading cause of death
in American women
• Pelvic Exam
• By 18 females should have pelvic exam from their physician
• Checks for size, shape and position of pelvic organs
• Pap test to check for cancerous cells on cervix
Problems of Female Reproductive System
• Menstrual Cramps
• Can occur at beginning of menstrual cycle
• Caused by contracting of muscles as lining is expelled
• Dysmenorrhea is severe or persistent cramping
• Usually requires professional health services
• Premenstrual Syndrome (PMS)
• Caused by hormonal changes
• Experienced 1-2 weeks before menstruation
• Can be physical or emotional symptoms including:
• anxiety, irritability, bloating, weight gain, depression, mood swings, and
fatigue
Problems of Female Reproductive
System
• Toxic Shock Syndrome (TSS)
• Rare but serious bacterial infection affecting immune system and liver
• Warning signs include fever, low bp, seizures, rash, organ failure, dizziness, and muscle ache
• To reduce risk use tampons with lowest possible absorbency and change frequently
• Vaginitis
• Most common vaginal infection in women of childbearing age
• Infection of the vagina caused by bacteria
• Discharge, odor, pain, itching and burning
• Can lead to PID
• Blocked Fallopian Tubes
• Leading cause of infertility
• Does not allow for release of egg
• Ovarian Cysts
• Fluid-filled sacs on the ovary
• If large enough, may require surgery
• Cervical, Uterine, Ovarian Cancer
• Early sexual activity and STDs are related to increased risk for cervical cancer
• Getting regular check-ups are important for early detection
Infertility
• Infertility- inability to conceive a child
• Endometriosis
• Migration and overgrowth of uterine tissue into ovaries and fallopian
tubes
• Treatment includes medication, hormone therapy and surgery
• Pelvic Inflammatory Disease (PID)
• Infection of fallopian tubes, ovaries, and surrounding areas of pelvis
• Usually caused by STDs
• Sexually Transmitted Diseases
• Can cause infertility and other disorders
• Some symptoms are not evident unless a medical exam is performed