Transcript SAP 1 – Students will analyze anatomical structures in

Endocrine System
Standards:
SAP 1 – Students will analyze anatomical
structures in relationship to their
physiological functions.
SAP 3 – Students will assess the integration
and coordination of body functions
and their dependence on the
endocrine and nervous systems to
regulate physiological activities.
The endocrine system is a group of glands that
transmit chemical messengers (hormones)
throughout the body
Glands with ducts (tubes) are exocrine glands
Examples: sweat glands
digestive glands - pancreas and liver
(bile duct)
Glands without ducts secrete hormones directly
into the blood are endocrine glands
Most hormones are proteins or shorter
protein-like molecules
Others are fat-like molecules called steroids
Glands
I. Pituitary Gland – master gland
Location – attached to hypothalamus
at base of brain
• direct link between endocrine and nervous
system
• 2 major lobes: anterior and posterior
A. Anterior Pituitary Hormones
1. GH – (growth hormone) – regulates growth
•
if too much is
released during
childhood = giant
ex. Andre the Giant
• if too little is released during childhood
= midget (perfectly proportioned
individual, only smaller
•
if too much is released during adulthood, a
condition called acromegaly results
Age 16
Age 33
Age 52
These individuals exhibit a thickening of the bones
of the hands, feet, cheeks, and jaw
Age 33
Age 52
Age 16
Age 24
Age 29
Age 37
Age 42
Acromegaly
Normal
2. ACTH – (adrenocorticotropic hormone) –
stimulates adrenal cortex to secrete
cortisol
3. TSH – (thyroid stimulating hormone) –
stimulates the thyroid gland to
secrete thyroxine
4. FSH – (follicle stimulating hormone) –
stimulates egg growth and the
secretion of estrogen in females and
sperm growth in males
5. LH – (luteinizing hormone) – stimulates the
ovaries to produce estrogen and
stimulates ovulation in females
Stimulates the testes to produce
testosterone in males
6. PRL – (prolactin) – stimulates milk
production in pregnant females
• some evidence that PRL enhances testosterone
production in males
B. Posterior Pituitary Hormones
1. Oxytocin – stimulates the uterus to contract
during childbirth
2. ADH – (antidiuretic hormone) or
vasopressin – stimulates kidneys to
return water to the blood
II. Thyroid Gland
Location – in neck near lower part of
larynx
larynx
thyroid gland
• butterfly shaped
1. Thyroxine – regulates metabolism;
necessary for normal growth
•
if too much thyroxine is produced, you
have hyperthyroidism – which causes
nervousness, sleep disorders, irregular
heart rate, and weight loss
• if too little thyroxine is produced, you
have hypothyroidism
Adults with hypothyroidism will tire easily,
have dry skin, and experience weight gain
Infants with hypothyroidism are said to have
cretinism – which results in stunted growth
and mental retardation
• If your diet contains too little iodine you may
develop a goiter (= enlarged thyroid gland)
Goiter is largely a condition of the past –
today, goiter is prevented by adding
iodine to table salt
2. Calcitonin – helps regulate the amount of
calcium in the bloodstream
• when the level of calcium in the blood
is high, the thyroid gland releases
calcitonin
•
calcitonin causes calcium to be
deposited in bone tissue, removing it
from the bloodstream
III. Parathyroid Glands
Location – embedded in the back of the
thyroid gland
• pea-sized
parathyroid glands
thyroid gland
1. PTH – (parathyroid hormone) – works with
calcitonin to regulate the levels of
calcium in the blood
• PTH is released if there is too little calcium
in the bloodstream – causes bone tissue to
be broken down, releasing calcium into the
bloodstream
IV. Adrenal Gland
Location – top of each kidney
• they can be separated into 2 regions: the
adrenal cortex (outer portion) and the adrenal
medulla (inner portion)
• adrenal cortex secretes a group (about 30)
hormones called corticosteroids which aid
metabolism, helps maintain salt and water
balance, and suppresses inflammation
A. Adrenal Cortex Hormones
1. Aldosterone – increases salt concentration
in the bloodstream by causing Na+
to be absorbed from the filtrate by
the kidneys
2. Cortisol – stimulates metabolism of
carbohydrates, lipids, and proteins
• hyposecretion of aldosterone and cortisol
causes Addison’s disease
Individuals with this disease suffer from
weight loss, muscular weakness, and mental
lethargy
B. Adrenal Medulla Hormones
1. Adrenaline - epinephrine
2. Norepinephrine
• these hormones are released anytime you are
placed in a stressful situation
• they cause an increase in heart rate, an
increase in respiration rate, the pupils to
dilate, an increase in blood pressure, restrict
blood flow to the skin and digestive system,
and stimulate the liver to release glucose,
prepares the body for action (fight or flight)
V. Thymus
Location – just behind the sternum
thymus
• unusual in that it is very
large in children, but
decreases in size as we
age
1. Thymosins – aid in T cell lymphocyte
maturation
VI. Islets of Langerhans
Location – a group of scattered cells
throughout pancreas
• the pancreas is unusual in that it functions
both as an exocrine gland and endocrine
gland
• most of its cells are exocrine in function –
they secrete digestive enzymes into the
duodenum
1. Insulin – lowers blood sugar levels by
stimulating liver and muscle cells
to remove glucose from the
bloodstream and store it in the
form of glycogen
• hypoglycemia – excess insulin production
results in too little blood glucose
Individuals with hypoglycemia feel tired
and dizzy
• diabetes mellitus – too little insulin is being
produced, causing too much glucose to remain in
the bloodstream
• two types of diabetes mellitus – type I and type II
Type I diabetes occurs when the islets of
Langerhans are producing too little or no
insulin
• this type of diabetes is often called juvenile
onset diabetes because individuals who develop
it usually young
In type 2 diabetes, the levels of insulin being
produced are normal. However, cells do not
respond to it because there is something
wrong with their insulin receptors
• this type of diabetes is often called adult
onset diabetes because it usually does not
develop until later in life
• it is not known what causes type 2 diabetes;
however, we do know that heredity, obesity,
and smoking are contributing factors in its
occurrence
• type 2 diabetes is not as severe as type 1
diabetes. Type 1 can be treated only with daily
insulin injections. Type 2 can be treated by a
controlled diet
Symptoms of Type I diabetes include:
Frequent urination
Constant thirst
Extreme hunger
Weight loss
Fatigue
Irritability
Symptoms of Type II diabetes include:
Those of Type I +
Frequent infections
Blurred vision
Slow healing cuts and bruises
Tingling or numbness in the hands or feet
Recurring skin or bladder infections
2. Glucagon – raises blood sugar levels by
stimulating liver cells to convert
stored glycogen to glucose and
release it into the bloodstream
VII. Pineal Gland
Location – at the top of the brain stem
(above the pituitary)
1. Melatonin – function in humans is not
known. However, it is believed to be
involved in establishing daily biorhythms
and moods
• may be remnant from species in which day
length was important in selecting optimum
breeding times
VIII. Gonads – Testes and Ovaries
Testes
Location – in scrotum outside the body
cavity (where temperature is
lower – for normal sperm
production)
1. Androgens – the group of hormones that
the testes secrete. The main
androgen is testosterone
• testosterone stimulates development of male
secondary sex characteristics (deepening of
the voice, beard growth, body hair, broadening
of the chest, etc.) during puberty
Ovaries
Location – in the pelvic cavity
1. Estrogen – stimulates development of
female secondary sex
characteristics (growth of breasts,
widening of hips, body hair, etc.)
during puberty
2. Progesterone – prepares the uterus for
implantation of a fertilized egg
(maintains uterine lining)