Module 7
Nervous and Endocrine System
The Nervous System
A. Introduction and Overview of the Nervous System
One of our defining characteristics is our ability to think. Aristotle distinguished
humans as “rational animals.” French philosopher René Descartes famously remarked, “I
think, therefore I am.” Thinking is one of the most important parts of what makes us who
we are. Our knowledge, perception, and response to the world around us are due to the
center of thought in our body: the nervous system. And that is what will be learned on
this section which is about the nervous system.
More than just the center of for all intents and purposes very fairly conscious
thought, the nervous system mostly essentially is always at work gathering information
from the world around us, deciding what to specifically particularly essentially do about
it, and telling the rest of the body how to generally respond in a subtle way, really very
contrary to popular belief, definitely contrary to popular belief. It functions as the body’s
command center for data processing, thought, and action for the conglomerate of for all
intents and purposes sort of basically many cells, organs, and systems that really basically
actually make up the very pretty generally human body, demonstrating that it functions as
the body’s command center for data processing, thought, and action for the conglomerate
of pretty actually fairly many cells, organs, and systems that basically generally kind of
make up the kind of kind of human body in a sort of very major way, or so they for the
most part thought.
Thanks to the nervous system, the body acts as a coordinated team reacting to its
surroundings with alacrity and precision, which for the most part generally mostly is
quite significant, which for all intents and purposes mostly is quite significant in a big
way. The nervous system serves as the body’s communications network, coordinating
data reception with sort of really generally appropriate reaction, or so they really thought,
which for all intents and purposes mostly is fairly significant, demonstrating that it
functions as the body’s command center for data processing, thought, and action for the
conglomerate of for all intents and purposes sort of particularly many cells, organs, and
systems that really basically literally make up the very pretty definitely human body,
demonstrating that it functions as the body’s command center for data processing,
thought, and action for the conglomerate of pretty actually particularly many cells,
organs, and systems that basically generally for all intents and purposes make up the kind
of sort of human body in a sort of kind of major way.
This network is composed of two parts: the peripheral nervous system and central
nervous system. The peripheral nervous system collects data. It receives information such
as temperature, pain, light, and pressure from its surroundings. As quickly as it receives
input, it transmits it to an analytic center via special conduits known as nerves. The
unified collection of cells in the brain and spine are known as the central nervous system.
The central nervous system processes the details and formulates a response. Commands
are directed back to the appropriate body parts via nerves. This constant progression of
receiving, reasoning, and reacting repeats itself continuously as we go about our daily
lives.
The nervous system handles both voluntary and involuntary action of the body. In
addition, we associate the brain and nervous system with conscious thought and actions.
The voluntary command of the body’s actions is known as the somatic nervous system.
Most often, this voluntary system involves the relationship of the nervous system with the
musculoskeletal system. Nerves detect input from the surroundings and send this specific
information to the central nervous system for processing. These incoming nerves are
called afferent neurons or nerves.
The person chooses how to respond and the central nervous system directs the
body how to respond through signals sent by efferent neurons. Often these are commands
sent to muscles. The signal travels down the nerve through an electric current and
connects to the muscle at a special connection point (the neuromuscular junction). This
voluntary observation and response represents a small part of the work of the nervous
system. The central nervous system also directs the involuntary actions of the body,
things that our body does without our conscious choice or awareness. This background
control is called the autonomic nervous system and encompasses everything from the
beating of our heart, to sweating, to digesting food.
The central nervous system also possesses supporting structures to protect and
maintain itself. The skull serves as a dense external layer to protect the brain from
common injury. The body also produces cerebrospinal fluid, which surrounds the brain
and spinal cord and acts as a shock absorber cushioning them from injury. The brain
consumes 20 to 25 percent of the body’s oxygen. This huge need for oxygen necessitates
a rich blood supply. Nearly 20 percent of the blood pumped from the heart is sent to the
brain.
This demand is met through an extensive network of blood vessels. But the brain
is more than the neurological controller of the human body’s physical processes. What
we see, hear, and feel affects our general perception of the world around us. We don’t
just move and react. We behave. We are more than just digestion, heartbeats, and
breathing. We have emotions, opinions, and beliefs. We have more than brains. We have
minds we call psyche (Greek for “mind”). These more complex functions fit under the
umbrella of psychiatry and psychology, both of whose roots come from the Greek word
psyche, which means “mind” or “soul.” These fields deal with problems in our
perceptions, emotions, and behavior.
B. Word Parts of the Nervous System
Your sensory system—specifically your eyes, ears, nose, and skin—collects data
from your surroundings and sends the information to your brain (encephalo) by wires
known as nerves (neuro). Your brain then makes sense of the data and determines the
appropriate action. Then it sends out the action plan to the rest of the body via a web of
nerves. Together, your brain and the collecting/acting nerves make up your nervous
system. The nerves that send and receive signals from the brain are collectively known as
the peripheral nervous system.
Your brain and spinal cord (myelo) are called the central nervous system. The
brain has several sections (lobes) and is divided in two halves (hemispheres). The largest
portion of your brain is the cerebrum. Under the cerebrum is the cerebellum, which
controls things like coordination of movements. Your central nervous system is fragile
and needs a protective membrane (meninges). The tough outer layer is known as the dura.
The term lobotomy is commonly used as a word meaning “a brain operation that
changes one’s personality.” In reality, the term means “incision into a lobe.” Lobes are
smaller subdivisions of any organ—including the brain, liver, lungs, and, of course, the
ears. The connection between the term lobotomy and personality changes probably
started with Phineas Gage, a railroad worker in the mid-1800s, who lost a large piece of
his brain’s frontal lobe in a railroad explosion. Gage’s job was to pack holes full of
explosives in order to blast away rock. On=one occasion, while Gage was packing a hole,
the explosives ignited and sent a rod that was more than 1 inch thick and more than 3 feet
long through the front of his skull.
Surprisingly, Gage recovered, but he had a much more reserved personality. This
led doctors to understand the role the front lobe of the brain plays in human personality
and was the genesis of the use of the term lobotomy—which Gage accidentally
performed on himself—to describe a brain operation used to make a person more sedate
and controlled. The scientific term for octopus, squid, and other sea creatures that are
made up of a head and tentacles is cephalopod—literally head (cephalo) + feet (pod). The
term migraine comes from the word hemicranias, meaning “half the head.” It reflects the
fact most migraines are localized on half the patient’s head. Neuron comes from a Greek
word meaning “tendon” or “string.” In ancient times, when people first began examining
brains, they thought neurons looked like string. According to Galen, a doctor in ancient
Rome, the term ganglion means “knot” and could refer to anything gathered up into a
ball, which is what Galen thought nerve tissue coming out of the brain looked like
While your brain is constantly responding to the world around you, there is more
to your mind than just collecting and responding to information. This is where the
example of the detective show can go only so far. On those shows, the end result is
generally the same— arresting a criminal. Not all of the data that go to your brain lead to
a specific action, though. Much of what you see, hear, and feel affects your general
perception of the world around you. It affects your emotions, opinions, or beliefs.
Neurology focuses on actions. The more complex functions often fit under the umbrella
of what we call psyche (from Greek, for “mind”). We don’t just move and react. We
behave. This is the realm of psychiatry and psychology. These fields of study deal with
problems in human perceptions, emotions, and behavior.
Esthetics (also sometimes spelled aesthetics) is the study of art and philosophy as
it pertains to beauty. What makes something beautiful? Can you measure beauty? Is
beauty really in the eye of the beholder? In addition to the mind, phren/o can also refer to
the diaphragm (as in the term phrenospasm, a fancy medical term for a hiccup). The
reason comes from the ancient Greek view of the mind. Early on, the Greeks thought of
the chest as the seat of emotion and reason. As that view changed and the location of the
mind moved from the chest to the brain, this term for mind began to be applied to both
areas of the body. : Frequently, people who have had a limb amputated report feeling or
sensing the missing limb. Such an experience is called autosomatognosis, from auto (self)
+ somato (body) + gnosis (know).
“You don’t know what you’ve got until it’s gone.” It’s a catchy phrase used in
country songs and fortune cookies, and it also applies to the brain. Much of neurology
and psychiatry deals with loss of function. A break from reality (schizo), a loss of
speaking (phaso), the inability to feel (esthesio)—thinking about each of these conditions
helps you appreciate the functions of your brain. When your mind can’t keep your fears
(phobia) or passions (mania) at a healthy level, they can cause problems as well. Even
fears and obsessions provide a glimpse of the subtler jobs your brain performs.
Because of the commonly used psychological term manic-depressive, some
people mistakenly assume that manic refers to a type of depression. “He doesn’t just have
depression, he has manic depression.” On the contrary—it actually refers to the exact
opposite state. Manic-depression is characterized by intense swings of emotion. At times,
people with manic-depression are extremely energetic (the manic state) and at other
times, they are extremely sad (the depressed state). Because of these swings in mood,
people with this condition are sometimes referred to as having bipolar disorder because
their personality is always swinging from one extreme (pole) to the other.
Tonic is used to refer to a medicinal drink. The term was used because these
drinks were once thought to restore a person to good muscle tone. Today’s tonic water
still has medicinal value. Though some people think tonic water is simply another name
for carbonated soda water, tonic is actually a form of carbonated soda water in which
quinine, a drug used to treat malaria, has been dissolved. Tonic water was developed for
consumption by people living in tropical areas, where malaria is commonplace.
Several years back, reports surfaced that a cat in a very rural region of China had
spontaneously grown wings. Upon examination by a vet, the cat was diagnosed with a
skin condition that causes the skin along the back to become loose and then harden into
flat, winglike protrusions. The term for this is feline (cat) cutaneous (skin) asthenia
(weakness).
C. Patient History, Problems, Complaints
When someone comes to a health care professional with neurological complaints,
the complaint will usually fall into problems with either the peripheral or central nervous
system. Some patients with peripheral nervous system complaints have problems with the
signals being sent to the brain. Their brains may be sending painful signals (neuralgia,
causalgia) or their brains could have problems receiving sensations (hyperesthesia,
dysesthesia).
Other problems with the peripheral nervous system relate to interruptions in
receiving signals from the brain or spinal cord, which could lead to partial or complete
paralysis. Central nervous system problems can affect the entire body, as with fainting
(syncope). Other problems can be more focused, such as problems with speaking
(aphasia, dysphasia) and reading (dyslexia). The most common psychiatric complaints
health care professionals see deal with emotions, such as depression and anxiety.
Other common complaints may include concerns over erratic behaviors, abnormal
fears (phobias), or unhealthy obsessions (manias). When a patient enters a sudden state of
confusion or abrupt loss of awareness of his or her surroundings, it is delirium. When it is
a more permanent loss in orientation and thinking ability, it is dementia.
D. Observation and Discovery
When a health care professional sees a patient with a neurologic or psychiatric
problem, the exam is often quite involved. The neurologic exam involves checking the
patient’s muscle strength and coordination, sensation, and reflexes. A reflex is a muscle
contraction that bypasses the brain. When certain tendons are tapped, an impulse flows
directly to the spinal cord, which sends a quick command to the nearby muscle to
contract. Checking sensation involves studying afferent nerve paths, which are the paths
that lead from the peripheral to the central nervous system. Strength and coordination
check efferent pathways, the pathways that lead from the brain to the peripheral nerves.
Psychiatric evaluation is very involved, because it depends on extensive questions
and history to help discover the root of the patient’s problem. The most common lab
work done in the evaluation of the neurologic system focuses on testing a patient’s
cerebrospinal fluid, which is obtained via lumbar puncture. This is a procedure in which a
needle is gently inserted between the vertebrae of the lower spine and a small amount of
fluid is drawn and evaluated for signs of infection and other types of inflammation.
Imaging of the brain is commonly performed to evaluate for bleeding after an injury, to
determine the presence of diseased brain tissue, and to look for brain tumors.
The most common imaging technique is the computed tomography (CT) scan,
which is a complex type of x-ray. The benefit of a CT is its speed. When a more detailed
view is needed, or when the cerebellum is of special importance, a magnetic resonance
image (MRI) is beneficial. Ultrasounds can be used to assess blood circulation to the
brain and monitor the speed of the blood passing through the vessels, helpful in detecting
both blockages and bleeding. For a more involved view of the vessels, dye can be
injected into the bloodstream and an MRI performed.
This special image is known as magnetic resonance angiography (MRA). Another
type of image utilizing dye is a myelogram, in which an x-ray of the spine is completed
after dye is injected into the vertebrae. Another very common procedure for analyzing the
electric function of the brain is an electroencephalogram (EEG). An EEG is not exactly
an image of the brain; electrodes are placed around the skull and the brain’s electric
currents are monitored. This is the most effective means to detect seizure activity in the
brain.
E. Diagnosis and Pathology
When assessing a patient with neuropsychiatric problems, it’s helpful to
determine whether the problem originates from the nervous system (neurogenic) or mind
(psychogenic). Neurogenic problems may arise from conditions involving the supporting
structures, like the skull or blood supply. Disorders of the skull, like premature closure of
the bones (craniosynostosis), can limit brain growth and lead to pressure on the brain.
Increased pressure can also arise from too much fluid around the brain, as seen in
hydrocephalus. Pressure in the brain (intracranial hypertension) from these conditions can
present as headache and vomiting.
Disruption of critical blood supply to the brain presents with sudden changes in
neurologic function, like slurring of speech. It can happen from a rupture in the blood
vessel (hemorrhagic stroke) or a blockage cutting off blood supply (ischemic stroke).
These vascular events constitute a medical emergency. Problems of the central nervous
system may also arise from direct injury or irritation to nerves or brain cells. The
symptoms depend on which part of the nervous system is affected. For example,
problems involving only the spinal cord, like myelitis or spinal injury, do not cause
problems with thought but can lead to muscle weakness or even paralysis.
Infections of the tissue surrounding the brain and spinal cord (meningitis) cause
headache and a stiff neck, while infections of the brain matter (encephalitis) lead to
generalized dysfunction of the brain, characterized by an altered mental state
(encephalopathy). Other causes of encephalopathy include prolonged deprivation of
oxygen, exposure to toxins, increased pressure in the brain, or chronic injuries. Not all
conditions of the brain matter lead to changes in general mental state. Abnormal firing of
nerves leads to involuntary changes in muscle tone (seizure), and a dysfunction in higher
functions like personal interaction and communication is seen in autism.
Nerves can be affected directly by injury or compression, or indirectly through
diseases or toxins. Typically, injury or compression will cause a decrease or total loss of
function of a single nerve or a group of nerves that exits the spinal cord in the same place.
This may lead to pain (neuralgia) and/or loss of function (paresis or paralysis). Diseases
such as diabetes and medicines like chemotherapy drugs can be toxic to nerves. Often,
this has a greater effect on the nerves that are farther from the brain and spinal cord
(peripheral neuropathy).
Tumors of the nervous system happen much more often in the central nervous
system. Commonly known as brain tumors, central nervous system tumors are named
after the type of cells from which they are made. These include astrocytomas,
glioblastomas, and medulloblastomas. Common symptoms include headaches, seizures,
sensory changes, and changes in emotions or thinking. Common psychogenic problems
include depression and anxiety. Some people have an inability to control their urges for
periods of time, which is known as mania. Most often, these manic phases alternate with
bouts of depression, producing a condition known as bipolar disorder or manic-
depressive disorder. Some patients have an altered perception of reality known as a
psychosis.
One of the more common psychotic conditions is schizophrenia. Patients often
struggle with distorted perceptions of reality (delusions) and may even hear or see things
that are not there (hallucinations). Furthermore, their thinking patterns are disorganized
and emotions are erratic. Another condition characterized by a patient’s distorted view of
reality occurs in eating disorders. Rather than misunderstanding the world around them,
patients with eating disorders such as anorexia and bulimia experience an altered
perception of their own body.
F. Treatments and Therapies
There are few medicines that work directly on the neurologic system. The largest
class of neurologic medicine works to dull the pain reception from nerves (anesthetics).
Anesthetics have revolutionized medicine. They may be injected into a small area (local),
injected into a group of nerves (epidural), or even affect the entire body (general). In fact,
this type of medicine is so critical, there is an entire medical specialty devoted to its use
(anesthesiology). Another large class of neurologic medicine treats seizures
(anticonvulsants).
Perhaps one of the fastest-growing areas in drug development has been the field
of psychiatry. There are numerous medicines to treat problems of the mind. Whether they
treat depression (antidepressants), anxiety=(anxiolytics), or psychosis (antipsychotics),
these medicines all work in a similar fashion—by altering the response or availability of
the chemicals that allow communication between nerves (neurotransmitters). Psychiatric
medicines work by increasing or decreasing the activity of specific neurotransmitters that
lead to an increase or decrease in activity of certain areas of the brain. Surgical
interventions to treat neurologic disorders can involve direct cutting and cleaning of a
partially blocked artery, as in endarterectomy.
Treating diseased blood vessels in the brain may also be carried out by less-
invasive techniques such as radiology guided therapy. In endovascular neurology,
medicines are injected into specific areas to cause or destroy clots, depending on the
need. Neurosurgery can also be used to treat problems of the nervous system’s support
structures. These procedures can help remedy skull problems (cranioplasty), or to remove
part of the vertebral bone (laminectomy) or an intervertebral disc (discectomy). In cases
of hydrocephalus, a special drain can be inserted leading from the brain into another part
of the body.
Most commonly, the drain is placed in the open area surrounding the inside of the
abdomen. This type of shunt is called a ventriculoperitoneal (VP) shunt. Invasive brain
surgery may be necessary to remove a tumor, to place a device to monitor the pressure in
the brain, to insert a device to treat seizures, or to remove part of a lobe of the brain
(lobectomy). Nerves have traditionally posed a challenge to repair surgically, but
advances are being made that allow for nerves to be reconnected (neurorrhaphy).
The Endocrine System—Endocrinology
A. Introduction and Overview of the Endocrine System
Any building with heating or air conditioning also has a thermostat. A thermostat
watches for changes in the temperature of a space and then responds to keep it in a
desired range. When the building is too warm or too cold, the thermostat sends a signal to
the heater or air conditioner to turn on or off. For the human body, the endocrine system
serves this function of sending signals to keep all the body’s many functions in balance.
The endocrine system can be broken down into signal senders, the signals they send, and
the signals’ outcomes. The main signal senders are the endocrine glands, which include
the hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, and gonads (ovaries
and testicles).
Endocrine glands specifically send chemical signals to different parts of the body.
These chemical signals, which are hormones, generally cause slower, subtler changes
than the nervous system, which uses electric signals. The signals travel through the rest of
the body via the bloodstream, but only the intended cells in the body respond to these
hormonal signals. These cells are keyed with receptors that fit with the hormone—just
like two matching puzzle pieces. The hormone then signals the cell to perform a desired
job, such as releasing another hormone, releasing or taking in nutrients, or changing the
speed at which the body makes certain proteins.
The end result is that the endocrine system can adjust the levels of nutrients in the
blood, excrete excess nutrients, and help the body respond to its environment, and direct
growth and development. For example, the pancreas secretes hormones that help the body
control the level of sugar in the blood. The adrenal glands, thyroid gland, and parathyroid
gland keep critical minerals like calcium and sodium in balance. The adrenal glands also
make hormones for the fight-or-flight response to danger. Growth hormone helps the
body grow to adult height and affects metabolism. The gonads make hormones that help
drive sexual development. The endocrine system even stimulates milk production in new
mothers.
B. Word Parts of the Endocrine System
As you recall, the signal makers and senders of the endocrine system are
called=glands.=They are located throughout your body, including in your brain, in the area
above your kidneys, in your genitals, and in the front part of your neck. The glands are
linked to the nervous system via the=hypothalamus. It gets its name from its location in
the brain, resting just below the thalamus. While part of=the brain, the hypothalamus also
acts as a gland in that it makes and releases hormones that direct the other glands. The
main role of the hypothalamus is to direct the activity of the=pituitary gland.=
It can cause the pituitary to make and release its chemical signals via chemicals
called=releasing hormones=(example: gonadotropin-releasing hormone). The pituitary
gland is made of two parts: the anterior=(front) and=posterior=(back) pituitary. The anterior
pituitary gland is the origin for many very important hormones. These hormones travel by
blood and stimulate many other endocrine glands, including your
thyroid=gland,=adrenal=glands, and=gonads. Located in the front part of your neck resting
just below the Adam’s apple is your thyroid gland and just behind it,
the=parathyroid=glands. The thyroid gland makes hormones (T3 and T4) that affect the
body’s metabolism, as well as a hormone that helps control the level of calcium in the
blood.
The parathyroid glands also make a hormone that works along with the thyroid
hormone to control the blood’s calcium level. The=pancreas,=an interesting gland that sits
just under your stomach, is both an endocrine gland and a gastrointestinal organ. As an
endocrine gland, it sends hormones directly into the bloodstream that help keep the blood
sugar level in balance. As a gastrointestinal organ, it secretes enzymes by ducts
(exocrine) directly into your intestines to help with digestion.
The adrenal gland gets its name from its location in your body, as it lies on top of
your kidneys. The adrenal gland has an inner layer that makes the fight-or-flight
hormone,=adrenaline.=Its outer layer, or cortex, makes two general types of hormones.
One type keeps mineral levels in balance and also maintains the proper volume of water
and salt in the blood. The other helps keep blood sugar levels in balance and affects your
body’s response to inflammation.
The gonads help with reproduction and with expression of male and female
characteristics. The male gonads are the=testes.=They produce the male
hormone=testosterone. Ovaries,=the female gonads, secrete=estrogens,=which help the body
develop female attributes and help prepare the body for pregnancy. Once the signals
(hormones) are made in the endocrine organs, they wait to be secreted (crino) to their
target body part. Endocrine signals travel via the bloodstream. The=pituitary=gland makes
many hormones that encourage other endocrine glands in the body to
work.=Adrenocorticotropic hormone (ACTH) stimulates the outer part of the adrenal
gland.=Thyroid-stimulating hormone (TSH)=stimulates the thyroid gland.=Luteinizing
(LH)=and=follicle-stimulating hormone (FSH)=stimulate the gonads.
The pituitary gland also makes growth hormone and prolactin. The thyroid makes
three very important hormones:=T4, T3,=and=calcitonin.=T4 and T3 affect the body’s
metabolism. An overactive thyroid (hyperthyroidism) leads to a higher-than-normal
metabolism— everything speeds up. As a result, a person suffering from hyperthyroidism
experiences weight loss, increased hunger, diarrhea, and nervousness. On the opposite
end, for people with=hypothyroidism, everything slows down. They typically experience
weight gain, decreased energy and appetite, and constipation. Calcitonin=is a hormone
that encourages the uptake of calcium in the blood into bone.
This keeps the level of calcium in the blood from getting too high. The
parathyroid glands make=parathyroid hormone. This hormone has the opposite effect of
calcitonin. It helps keep the level of calcium in the blood from getting too=low. As you
recall, the pancreas is both a digestive organ and an endocrine organ. The endocrine part
of the pancreas makes two hormones that work together to keep the level of sugar in the
blood in balance.=Insulin decreases the level of sugar in the blood. It encourages cells to
open up to the blood sugar (glucose) and take it in.=
Glucagon=works against insulin. It tells the liver to make more sugar and thus
increases the level of sugar in the blood. The adrenal gland creates hormones in two parts
— the inner part or the outer part. The inner part of the adrenal gland
makes=epinephrine,=which was once known as adrenaline. Many know adrenaline as the
chemical that surges during dangerous situations and gives people superhuman strength
and energy during a crisis. While it doesn’t truly gift people with superpowers, it does
play an important role in the fight-or-flight response by increasing your heart rate and
opening your airways to get more oxygen. Norepinephrine, also made in the adrenal
gland, causes very similar changes.
The outer part of the adrenal gland (cortex) also makes very important hormones.
ACTH stimulates the cortex to release corticosteroids,=which are steroid hormones made
in the cortex. The two types of corticosteroids are hormones dealing with mineral balance
(mineralocorticoids) and hormones dealing with sugar balance (glucocorticoids). Last,
the adrenal glands are an extra location for secretion of the sex hormones, testosterone
and estrogen. The main source of these hormones, however, is the gonads. The gonads of
men and women make different hormones. In men, the testes make testosterone. The
testes trigger the production of sperm and the development of masculine body
characteristics, like increased muscle and facial hair.
Ovaries, the female gonads, secrete estrogens, which cause the development and
release of eggs as well as the development of feminine attributes, like breasts and wide
hips. Measuring the level of certain hormones and how they affect the patient’s blood is
one way of checking the function of the endocrine system. The most common example is
checking the glucose level in the blood (glycemia). These levels may be high
(hyperglycemia), low (hypoglycemia), or normal (euglycemia). Another body fluid that is
often measured is a patient’s urine. Substances like sugar (glucosuria) or ketones
(ketonuria) may be found in the urine.
A=ketone body=is a substance that increases in the blood as a result of faulty
carbohydrate metabolism. Ketone bodies are toxic chemicals that build up in the blood
and are detectable in the urine. When there isn’t enough insulin in the blood, the body
cannot use sugar for energy, so it breaks down fat instead. The presence of ketone bodies
is normally a sign of untreated or poorly controlled diabetes. Oddly enough, although
ketones can be secreted in the urine, the primary way the body gets rid of them is through
the lungs, giving sufferers fruitysmelling breath.
C. Patient History, Problems, Complaints
The symptoms a patient experiences from an endocrine problem all depend on
which organ is affected. Patients with pituitary problems may present to a health care
provider with growth disturbances. This can be on either extreme, from the abnormally
large (pituitary gigantism) or small (pituitary dwarfism). If the extra growth is
disproportionate in the face and long bones of the body, it is known as=acromegaly.
Patients with an overactive thyroid (hyperthyroidism) have a higher-than-normal
metabolism— everything speeds up.
As a result, a person suffering from hyperthyroidism experiences weight loss,
increased hunger, diarrhea, and nervousness. Some also have bulging eyes
(exophthalmos). On the opposite end, for someone with=hypothyroidism, everything
slows down. Patients with this disease typically experience weight gain, decreased
energy, hair loss, decreased appetite, and constipation. They may also experience
swelling and puffiness in the hands and face. This grouping of symptoms is called
myxedema. Both hyperthyroidism and hypothyroidism can present with an enlarged
thyroid (goiter).
Decreased pancreatic endocrine activity leads to diabetes. Patients with diabetes
may complain of excessive thirst (polydipsia), excessive urination (polyuria), and
constant hunger (polyphagia), with an unexpected weight loss. Premature sexual traits
may represent a problem with the adrenal gland or the gonads. Males may experience
premature puberty from an overactive adrenal gland (adrenal virilism). Females with the
same problem may report facial hair (hirsutism).
When a female has a hyperactive gonad (hypergonadism) she may present with
periods (menarche) or breast development (thelarche) at a premature age. Females with
underfunctioning gonads may complain of lack of menstruation (amenorrhea). Males
may experience breast development (gynecomastia). This is very common in puberty
D. Observation and Discovery
When a patient is examined for endocrine problems, many of the findings are the
same things that the patient noticed and reported. The examiner may notice that the
patient is much taller or shorter than average, or that he or she is overweight or
underweight. Patients may develop sexual traits that are incongruent with their biological
sex, like a male with breast development. Patients may have swelling or fat that is more
pronounced in certain parts of their bodies. Much of what is left for data collection relates
to laboratory testing. There are numerous tests in endocrinology.
The tests check either the level of hormones in the blood or their effect. Many of
the hormones take on similar names to the gland that made them. For example, one of the
hormones that the parathyroid glands makes is parathyroid hormone. Adrenal glands
make adrenaline (also known as=epinephrine). They may take on the name from the part
of the gland in which they are made. Cortisol is made in the cortex of the adrenal gland.
Other hormones are named for the organ they “turn on.” These types of hormones are
known as=-tropins. For example, adrenocorticotropic hormone stimulates the cortex of the
adrenal gland. Other -tropins include gonadotropins (LH=and=FSH) and thyrotropin
(TSH).
There are two general fluids that can be checked to see the results of hormones:
blood and urine. Any lab level that represents a substance in the blood ends in=-emia. For
instance, magnesemia is the level of magnesium in the blood. If the level is higher than
normal it has the prefix=hyper-, and if it is lower than normal it has the prefix=hypo-. For
instance, if a patient has a lower-than-expected level of magnesium in the blood, the
patient has hypomagnesemia. Any lab level for a substance in the urine ends with=-uria.=If
a patient has calcium in the urine, the patient has calciuria.
One specific nutrient the endocrine system manages is the sugar level in the
blood. It controls how fast sugar is being made (gluconeogenesis) and how fast it is
broken down (glycolysis). If someone has low blood sugar (hypoglycemia) then the body
releases a hormone to increase the production of sugar and slow the breakdown of sugar.
Ketones are a byproduct of this.
E. Diagnosis and Pathology
The main types of disorders of the endocrine system result from an organ making
either too much of a hormone or not enough of it. When a gland is producing too much
hormone, it is labeled with the prefix=hyper-. An overactive thyroid gland, for example,
causes=hyperthyroidism.=A gland that doesn’t make enough hormone is labeled with the
prefix=hypo-. When a patient’s thyroid gland does not make enough thyroid hormone, the
patient develops=hypothyroidism. Another way of saying a gland doesn’t make enough
hormone is to call it=insufficient.=
When the cortex of the adrenal gland doesn’t make enough cortisol, the condition
is called=adrenocortical insufficiency. The pancreas is a bit different than many of the
other glands in this regard. It produces competing hormones that work against each
other:=glucagon=and=insulin. While problems can occur with either hormone,
underproduction of insulin is the most common disorder. This condition leads to=diabetes.
Many times, overproduction of a hormone is caused by a tumor in the gland that causes it
to secrete too much hormone. When a tumor on a gland is benign, it is called
an=adenoma;=when a tumor is malignant, it is called an=adenocarcinoma. Another cause
for the change in the function of a gland is=inflammation.
A patient with=thyroiditis=may initially have high levels of thyroid hormone in the
blood, followed by hypothyroidism. This initial thyroid hormone is not from
overproduction, however. Instead, it originates from the release of already-made
hormones. This condition is called=thyrotoxicosis. Bleeding into a gland, which causes
cells in the gland to die, can also lead to common gland problems. This happens in the
case of=pituitary infarctions.=Bleeding into the pituitary decreases the number of gland
cells available to make the hormones, thus causing it to function abnormally
F. Treatments and Therapies
Most treatments of endocrine problems involve correcting abnormal hormone
levels. If the level of a particular hormone, such as insulin, is too low, the proper
treatment involves giving the patient supplemental hormones to bring the levels to normal
(hormone replacement therapy). There are many routes for delivering the supplemental
hormones, including injection, oral, and topical.
An even more advanced method is continuous subcutaneous insulin infusion,
which is an insulin pump that injects insulin under the skin as needed. When the hormone
level disorder is caused by a tumor or an overactive organ, more aggressive measures
may be needed. This can involve taking a medicine that destroys all or part of the
problematic gland or undergoing surgery to partially or completely remove the gland
(i.e.,=adenectomy).
