Physiology for CNA's & HHA's

Transcription

1 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

2 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

3 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

4 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

5 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

6 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.