Download A quick summary: The skeletal system is made up of

Physiology for CNA's & HHA's
INTRODUCTION
Learning anatomy involves memorization but physiology requires a deeper
understanding. In anatomy, we simply learn what things are. In physiology, we learn how
they work.
A quick summary: Physiology is defined as the study of the function of the organs and
tissues of the body.
One of the key elements in becoming familiar with physiology understands the concept
of feedback. The body is constantly experiencing change so it must constantly adjust.
The body is also constantly trying to maintain a stable internal environment. In order to
respond to change and to maintain that stable internal environment, the body must be able
to self-regulate. It does this by receiving feedback and sending out feedback. This
example illustrates the concept.
When you walk quickly up a flight of stairs, your muscles work harder and need more
fuel and oxygen. Nerve receptors in the muscles send this information, this feedback – we
need more fuel and oxygen – to specific areas of the brain. In response, the brain sends
out signals – again, feedback – through the peripheral nerves to the blood vessels, the
heart, and the lungs. The signals cause the blood vessels to dilate so they can deliver
more blood, they cause the heart to pump faster and stronger, and they increase the rate at
which you breathe.
A quick summary: The basic mechanism of physiology by which the body responds to
change and maintains a stable internal environment is feedback.
OBJECTIVES
When the student has finished this module, he/she will be able to:
1. Identify a definition of physiology.
2. Identify the basic mechanism of physiology that the body uses to respond to change.
3. Identify the basic function of the nervous system.
4. Identify the basic functions of the circulatory system.
5. Explain how the respiratory system regulates oxygen and carbon dioxide levels.
6. Identify an important function of the respiratory system.
7. Identify the two basic functions of the digestive system.
8. Identify two important functions of the liver.
9. Identify the basic function of the pancreas.
10. Identify the function of insulin.
Skeletal System, Muscles, and Skin
The bones of the skeletal system and their associated structures, the three types of
muscle, and the skin are physiologically active. However, aside from the cardiac muscle
(which will be discussed later), the basic functions of these structures and how they work
is not crucial knowledge for Cans and won’t be covered in this module.
Nervous System
The nervous system coordinates and controls the body at the most basic level by
providing us with the ability to see, smell, taste, hear, and touch. The nervous system
gives us the ability to speak, the ability to detect pain and changes in temperature, and the
ability to oversee and regulate our vital organs such as the heart, kidneys, lungs, etc.
All of these functions are controlled by special areas in the brain. The peripheral
nerves send messages to the brain about our external and internal environment. In
response, these special areas of the brains send out signals through the spinal cord and the
peripheral nerves to all of these parts of the body. If there are changes in our external
environment (a change in room temperature) or changes in our internal environment
(when we have pain or one of our organs is not functioning properly), the brain receives
this information, then can make corrections so our body can operate efficiently and we
remain healthy and safe.
Learning Break: A stroke is a common neurological disaster that occurs when a blood
vessel in the brain ruptures, or a blood clot obstructs an important blood vessel in the
brain. In either case, the brain no longer receives oxygen and nutrients. Brain tissue dies
and depending on the location in the brain of the stroke, the person may suffer paralysis,
lose the power of speech, or some other deficit.
But the nervous system also coordinates and controls our bodies in very sophisticated
ways. The brain gives us the powers of memory, problem solving, and abstract thought, it
enables us to plan for the future, and it is the place where our emotions are generated.
A quick summary: The nervous system controls the parts of the body that function
automatically such as breathing, heart beat, digestion, etc., and the parts of the body that
allow us to be awake, conscious, and avoid danger.
Learning Break: Damage to the nervous system can take many forms. One of the most
common is Alzheimer’s disease. This disease causes destruction of the parts of the brain
that control memory, the ability to plan, and language. A person who is suffering from
Alzheimer’s disease often cannot remember people he/she has known for years, cannot
remember simple facts such as his/her home address, and has difficulty in expressing
thoughts and feelings.
Circulatory System
The heart beats rhythmically and automatically. Each time the heart beats, it sends out
a volume of blood through the arteries, capillaries, and veins. (Note: A normal heart rate
is 60 to 100 beats a minute). The two basic functions of the circulatory system are to a)
circulate the blood to the organs and tissues so they can process the fuel they need to
operate and to eliminate waste products that would stop normal body functioning, and b)
carry nutrients and drugs to the body.
Both of these are absolutely vital. Our bodies need fuel to operate. We need the energy
that we get from that fuel (carbohydrates, fats, proteins, vitamins, minerals, etc.) for the
muscles to work, for the brain and nervous system to operate, and for all of the normal
processes such as breathing, growth, repair and recovery from injuries/disease, and
fighting off illnesses. However, without oxygen, we cannot process the fuel and the
nutrients that we take in with our diets, so the circulatory system is absolutely vital.
We also generate waste products from metabolism and all of these body processes. If
these are allowed to accumulate, our bodies would cease to work. Some of them can be
eliminated through the digestive system and the renal system, but many are eliminated
through the lungs by way of the circulation. The waste products combine with the blood
(after the blood has delivered its load of oxygen) and then this blood is pumped back to
the lungs. As mentioned previously, at that point, these waste products move from the
blood into the alveoli and they are removed when we exhale.
Finally, the drugs we take and the nutrients we ingest are absorbed by the blood which
is then circulated throughout the body, delivering them to where they are needed.
The circulatory system is not under conscious control. Instead, it operates
automatically by using feedback mechanisms. For example, when the body senses that
more oxygen is needed, or that waste products are building up, signals are sent back to
the brain. The brain responds by activating nerve pathways that increase the heart rate
and the blood pressure. Heart rate and blood pressure also respond by slowing down and
decreasing when we are less active.
A quick summary: The basic functions of the circulatory system are to a) circulate the
blood to the organs and the tissue so they can process the fuel they need to operate and to
eliminate waste products that would stop normal body functioning, and b) carry nutrients
and drugs to the body.
Learning Break: People with heart disease (atherosclerosis) often have arteries in the
heart that have become narrowed with cholesterol deposits. Because of this, blood supply
and oxygen delivery to the heart is decreased. If someone with heart disease and clogged
arteries experiences a situation in which the body needs more oxygen (emotional stress,
intense physical activity, etc.), the heart must pump faster and harder. But when the heart
has to work harder, it needs more oxygen, too. And if the arteries are clogged and can’t
deliver blood with oxygen, the heart muscle can be damaged or die – in short, the person
can have a heart attack or a cardiac arrest.
Respiratory System
The respiratory system delivers oxygen to the blood when we inhale and allows for
waste products to be removed when we exhale. It functions as the entry point of oxygen
to our bodies and as the exit point for waste products. We normally breathe about 12 to
20 breaths a minute, and the respiratory system is not under conscious control. Instead,
like the other body systems, it operates by feedback mechanisms. When the body senses
that more oxygen is needed, or that waste products are building up, signals are sent back
to the brain. The brain responds by activating nerve pathways that increase the rate of
breathing and the depth of each breath. (Note: The most important waste product that is
eliminated when we exhale is carbon dioxide). The faster and deeper we breathe, the
more oxygen we take in and the more carbon dioxide we eliminate.
A quick summary: The basic functions of the respiratory system are to deliver oxygen
to the blood and remove carbon dioxide from the blood. The lungs do this by regulating
the rate and depth of breathing so enough oxygen reaches the body and enough carbon
dioxide is removed.
Learning Break: People who have developed emphysema (also called chronic
obstructive pulmonary disease, or COPD) from years of cigarette smoking have damaged
lungs. When a person with COPD inhales, oxygen cannot pass through damaged and
scarred lung tissue into the blood. When that person exhales, carbon dioxide cannot leave
the blood. The lack of oxygen and the buildup of carbon dioxide cause shortness of
breath and an inability to perform simple physical tasks.
Digestive System
The digestive system is in place to deliver food, nutrients, and fluids to the body. Once
these are in the stomach and the small bowel, the digestive system uses secretions that it
produces to break them down so they can be used. It also is an important pathway for
elimination of the parts of food we cannot digest (some fibers, for example) and for the
elimination of certain waste products (parts of drugs that have been taken and byproducts
of metabolism) by way of defecation (expelling bowel movements). The liver has many
complex functions. It stores blood sugar, it makes products that help the blood clot if we
bleed, and most importantly, it metabolizes drugs and breaks down metabolic wastes. The
digestive system is not under conscious control.
A quick summary: The digestive system allows for entry of food, nutrients, and fluids to
the body. Its two basic functions are absorption and breakdown of the food we eat and
the elimination of undigested food and waste products. The most important functions of
the liver are to metabolize drugs and break down metabolic wastes.
Learning Break: The digestive system eliminates waste by expelling stools. If the
digestive system is not functioning properly, stool can be retained in the digestive tract
(constipation) or stool can be excessively formed and eliminated (diarrhea). In either
situation, the patient’s basic health can be impacted. Constipation can cause hemorrhoids
or anal tears, and diarrhea can cause dehydration.
Renal System
The renal system is complex. It is responsible for excreting most of the waste products
of metabolism. It is responsible for maintaining the proper balance of fluid in the body. It
makes sure that the blood has exactly the right amount of acidity, and it excretes or
retains certain substances such as potassium and sodium in order to maintain their proper
concentration in the blood. The renal system accomplishes all of these functions by
producing urine, and controlling the amount and the composition of the urine that it
makes.
Once again, the renal system is a body system that operates using feedback. A major
part of the blood flow in the body moves through the kidneys. As the blood passes
through the kidneys, urine is formed and delivered to the body. Sophisticated sensors in
the kidneys can detect when there is an excess of waste products and increase their rate of
elimination in the urine. Other feedback mechanisms sense when the body is dehydrated
or when there is a fluid overload. If either of these two situations occurs, the kidneys can
respond by making more or less urine. And if the level of sodium, potassium, or acids
(these are produced by metabolism) is too high, the kidneys can sense this and change the
composition of the urine so that these substances are eliminated or conserved.
A quick summary: The renal system is responsible for excreting the waste products of
metabolism, for maintaining the proper fluid balance in the body, and for controlling the
levels of acids and minerals in the blood. The two basic functions of the renal system are
making urine and changing the amount and the composition of the urine that is formed.
Learning Break: Severe kidney disease damages the renal system and the kidneys can
no loner make urine. Often, these patients need dialysis. People undergoing dialysis have
a catheter permanently placed in a vein that allows for the removal of toxins that they
cannot eliminate by urinating.
Endocrine System
Although the endocrine system is relatively complicated and comprised of many
different glands, we will focus exclusively on the pancreas. This is, by far, the part of the
endocrine system that is most important for CNAs to be familiar with.
The major function of the pancreas is to produce insulin. Insulin is a hormone, and the
body cannot function without insulin. When we digest food, a large part of what we eat is
changed into glucose, also known as blood sugar. Our organs and tissues require glucose
and oxygen to function and survive, but glucose cannot enter the cells without insulin.
Our body also converts fats and proteins that we have stored into energy, but again, this
process requires insulin.
The pancreas can sense when the glucose level in the blood is too high or too low and
can adjust the amount of insulin it produces. It can also sense when fats and proteins need
to be converted into glucose and secret more insulin.
A quick summary: The pancreas produces insulin. Insulin is a hormone that carries
glucose into the cells and converts stored fats and proteins into energy. The two most
important functions of the pancreas of the endocrine system are regulation of blood
sugar levels and converting fats and proteins into blood glucose.
Learning Break: Diabetes is a very common disease. People with diabetes do not
produce enough insulin, and some don’t produce any insulin. As a result, their blood
sugars levels need to be constantly measured, and these levels can fluctuate wildly. If the
blood sugar is too low, the body – especially the brain – is deprived of fuel. As a CNA,
you will need to know how to recognize the signs and symptoms that the body does not
have sufficient energy to function because of low blood sugar. Most often, you will
observe sweating, pale skin, rapid heart rate, weakness, and confusion.
Reproductive System
It would be unusual for a CNA to need to actively monitor the functioning of a
patient’s/client’s reproductive system. However, CNAs should have a basic knowledge of
reproduction and the normal functioning of these organs.