Lesson 30 Outline list Lesson 32
Fundamentals of Biology
Lesson 31
The Endocrine System
I. Introduction
A. Endocrine System.
1. Definition: the ductless glands of
the body.
2. Purpose: regulate and control the
other body systems.
3. They do this by releasing chemical
messengers (hormones) into the blood stream.
4. The blood carries these hormones
to all the other parts of the body.
5. The effects are slower and
longer-lasting than those of the nervous system.
B. Hormones.
1. Chemical messengers produced in
the endocrine glands and carried by the blood to affect cells in other parts of
the body.
2. Proteins, amines, or sterols
(fats).
3. Carried by the blood.
4. Specific to one target site.
5. Secreted in small amounts.
6. Constantly removed from the blood.
a. Filtered
out by the kidneys.
b.
Deactivated by the liver or other glands.
c. Thus the
endocrine glands must continuously produce hormones to sustain their effect.
7. Quantity is usually self-regulated
by negative feedback mechanisms.
II. The Endocrine Glands.
A. Secretion.
1. Hyposecretion: abnormally low
level of production.
2. Hypersecretion: abnormally high
level of production.
B. Thyroid.
1. In front of the trachea, below the
larynx.
2. Produces thyroxin and calcitonin.
3. Thyroxin increases metabolism,
growth.
4. Regulated by thyroid stimulating
hormone from the anterior pituitary gland.
5. Calcitonin causes Ca2+
to move from the blood to the bones when blood Ca2+ gets too high.
C. Parathyroid.
1. Clusters of cells embedded in
tissue around the thyroid gland.
2. Produces parathyroid hormone.
3. Causes Ca2+ to move
from the bone to the blood.
D. Anterior pituitary.
1. In the base of the brain.
2. Growth hormone stimulates growth.
3. Thyroid stimulating hormone
regulates the thyroid gland.
4. Adrenocorticotropic hormone acts
on the adrenal cortex.
5. Gonadotropins control hormones
secreted by the reproductive organs.
6. Prolactin stimulates the breasts
to produce milk.
E. Posterior pituitary.
1. In the base of the brain.
2. Stores and releases 2 hormones
made by the hypothalamus.
3. Oxytocin causes the smooth muscles
to contract (e.g. uterus).
4. Antidiuretic hormone stimulates
the kidneys to reabsorb water..
F. Islets of Langerhans.
1. Over 1 million groups scattered
throughout the pancreas.
2. Insulin.
a. Stimulates
cells to take glucose from the blood.
b. Stimulates
conversion of glucose to glycogen.
c. Increases
movement of amino acids into cells.
3. Glucagon
a. Stimulates
liver to convert glycogen to glucose.
b. Stimulates
breakdown of fats to form glucose.
G. Adrenal.
1. On the top of each kidney.
2. Adrenal medulla (inner part)
produces epinephrine and norepinephrine (adrenaline and noradrenaline).
3. These greatly increase metabolism,
enabling stupendous physical feats.
4. Adrenal cortex produces
glucocorticoids.
5. They stimulate conversion of fats
and amino acids to glucose.
H. Sex hormones.
1. In males the testes produce
androgens, e.g. testosterone.
2. In females the ovaries produce
estrogens and progesterone.
3. The androgens and estrogens
produce secondary sex characteristics.
4. Progesterone stimulates
development of the uterus and the mammary glands.
III. Mind Control.
A. Man is one creature with two aspects: physical and
spiritual.
B. The brain is part of the physical aspect.
C. The mind is part of the spiritual aspect.
D. These two aspects are distinct, yet interrelated.
E. Thus the mind is related to the brain, but is not
identical to the brain.
F. The mind is a non-physical, spiritual part of man.
IV. Alcohol.
A. It can be a dangerous and deadly intoxicant.
B. The Bible warns us against the dangers of indulgence in
alcoholic drinks and declares the damnation of drunkards.
C. However, the Bible also portrays wine and “strong
drink” as natural elements of celebrations, notably the Lord’s Supper.
D. Principles governing the use of alcoholic beverages.
1. Drunkenness is forbidden.
2. Illegal use is forbidden (i.e.
under 21 yrs. old).
3. May be served at meals, especially
in celebrations, in moderation.
4. Must never be used in a way that
will cause others to stumble.
5. Care must be taken to avoid
dangerous activities (e.g. driving) while drinking alcoholic beverages.
6. If you are doing something so that
you may drink, you are drinking for the wrong reason.
V. Psychotropic Drugs.
A. Narcotics.
1. Produce euphoria.
2. Are physically addictive.
3. Morphine: derived from opium, the
dried sap of the opium poppy.
4. Heroin: derived from morphine.
5. Cocaine: derived from the leaves
of the coca plant.
6. Methadone: used to aid withdrawal
from other narcotics.
7. Codeine: pain killer.
B. Stimulants.
1. Increase the activity of the
central nervous system and often increase metabolism.
2. Create sense of high energy and
greater alertness.
3. Amphetamines: synthetically
produced.
4. Caffeine.
C. Depressants.
1. Slow down the central nervous
system.
2. Memory and thought are impaired.
3. Barbiturates: synthetically
produced.
4. Tranquilizers: less potent than
barbiturates.
5. Alcohol.
D. Hallucinogens.
1. Induce non-existent sensations,
visions.
2. LSD, DMT, STP: synthetic.
3. Mescaline: derived from a catus;
used in some Native American religions.
4. Marijuana: derived from the
Cannabis plant.
E. Use of psychotropic drugs.
1. They are illegal.
2. They are dangerous.
3. Their benefits are short-lived.
4. They are a substitute for God,
thus idolatrous.