Medical Assistant Physiology & Microbiology Terminology

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Daymar College

The medical assistant must become familiar with physiology and microbiology terminology. They must know about common diseases and the signs, symptoms and etiology of those diseases. The medical assistant must be aware of diagnostic measures and treatment modalities. They need to learn about disease incidence, prevalence, mortality and morbidity. The medical assistant also should know what constitutes an epidemic or pandemic.

The medical assistant will need to understand microbiology as it pertains to medical assisting. They must become familiar with cell structure, pathogens, non-pathogens, organisms, and microorganisms. The medical assistant will need to learn about infectious agents, their chain of infection and conditions of growth. They will need to become experts at Pathophysiology.

Pathophysiology and Disease Processes

Pathophysiology is a convergence of pathology and physiology. Pathology describes conditions observed during a disease. Physiology describes processes or mechanisms operation within an organism.

Signs, Symptoms, and Etiology of Common Diseases, Conditions, and Injuries

Arthritis – disease that affects joints, the tissues surrounding the joint and other connective tissue.

  • Signs of Arthritis – unusual fatigue, morning stiffness, joint stiffness, joint pain, minor joint swelling, fever, numbness and tingling, difficulty sleeping, loss of appetite and weight loss.
  • Symptoms of Arthritis – pain and stiffness in and around one or more joints. Also, swelling and reduced range of motion in the joints, ankle, back, fingers, hands, muscles, neck or wrist.
  • Etiology of Arthritis – Normal wear and tear. An infection or injury to the joints can break down the cartilage tissue or it can occur when the body’s immune system attacks the tissues of the body.

Asthma – a chronic condition that causes inflammation and narrowing of the bronchial tubes, where air enters and leaves the lungs.

  • Signs of Asthma - the frequent experience of shortness of breath or a wheezy sound in the chest when breathing. Tightness of muscles around the airway.
  • Symptoms of Asthma – coughing, shortness of breath and chest tightness.
  • Etiology of Asthma – exposure to various irritants and substances that trigger allergies

Chronic Obstructive Pulmonary Disease (COPD) – a collection of lung diseases that cause breathing problems and airflow obstruction.

  • Signs of COPD – an ongoing cough that produces a lot of mucus, shortness of breath, wheezing or a whistling sound when breathing and blueness of the lips or fingernail beds. Frequent respiratory infections, lack of energy, unintended weight loss, and swelling of the ankles, and feet or legs.
  • Symptoms of COPD – wheezing, chest tightness, ongoing cough, increased mucus, shortness of breath and fatigue.
  • Etiology of COPD – long-term exposure to lung irritants that damage the lungs including breathing in secondhand smoke, air pollution, or chemical fumes or dusts from the environment or workplace.

Type 2 Diabetes – the production of some insulin but not enough for the body to allow glucose to enter into the body’s cells.

  • Signs of Type 2 Diabetes – Initially there may be no signs of pre-diabetes. Slow-healing sores or cuts, itching of the skin usually in the groin area, frequent yeast infections, recent weight gain, velvety dark skin, numbness and tingling of the hands and feet, decreased vision and erectile dysfunction.
  • Symptoms of Type 2 Diabetes – increased thirst, dry mouth, unexplained weight gain, headaches, frequent urination, hunger, fatigue and blurred vision.
  • Etiology of Type 2 Diabetes – having too much sugar in the blood system. Genetics plays a role in Type 2 diabetes. People that are overweight and have a sedentary lifestyle may be more susceptible to Type 2 diabetes.

Heart Disease – heart conditions that include diseased vessels, structural problems and blood clots.

  • Signs of Heart Disease – most common sign of heart disease is chest pain. A discomfort, heaviness, pressure, aching, burning, fullness, squeezing or painful feeling in the chest.
  • Symptoms of Heart Disease – shortness of breath, palpitations, faster heartbeat, weakness, dizziness, nausea, and sweating.
  • Etiology of Heart Disease – plaque buildup thickens and stiffens artery walls that can inhibit the flow of blood to the arteries, organs and tissues. It can also be cause by unhealthy diet, lack of exercise, being overweight and smoking.

Hepatitis – an inflammation of the liver.

  • Signs of Hepatitis – Sometimes there aren’t any signs or the signs can be similar to the flu. Loss of appetite, fatigue, mild fever, muscle or joint aches, nausea, vomiting and pain in the belly.
  • Symptoms of Hepatitis – Dark urine, light-colored stool, jaundice, itchy feeling, mental changes or bleeding inside the body.
  • Etiology of Hepatitis – hepatitis viruses are the most common cause but other infections, toxic substances and autoimmune disease can also cause hepatitis. Hepatitis A is present in the feces of infected persons and is transmitted through consumption of contaminated water or food. Hepatitis B is transmitted through exposure to infected blood, semen or other bodily fluids. Hepatitis C is transmitted through exposure to infected blood. Hepatitis D occurs only in those who are infected with HBV. Hepatitis E is transmitted through the consumption of contaminated water or food.

Kidney Disease – can affect the way the body cleans the blood, filters extra water out in the blood and controls blood pressure.

  • Signs of Kidney Disease – swelling in the ankles, vomiting, weakness, poor sleep and shortness of breath.
  • Symptoms of Kidney Disease – fatigue, high blood pressure, loss of appetite, malaise, and water-electrolyte imbalance.
  • Etiology of Kidney Disease – can happen after a traumatic injury with blood loss, dehydration of the muscle tissue sending too much protein into the bloodstream, going into shock because of a severe infection, enlarge prostate that blocks the urine from flowing properly, certain drugs or toxins and complication during a pregnancy.

Meningitis – inflammation of the brain and spinal cord membranes.

  • Signs of Meningitis – pain in the back, muscles or neck, sudden high fever, severe headache that seems different than normal, irritability, seizures, sleepiness, light sensitivity, headaches, mental confusion and fear of loud sounds.
  • Symptoms of Meningitis – fever, chills, lethargy, loss of appetite, malaise, shivering, nausea, vomiting, blotchy or red rashes.
  • Etiology of Meningitis – typically caused by an infection. These infections include:
  • Pneumococcus – caused by pneumonia or ear/sinus infection.
  • Meningococcus – caused by meningococcal meningitis entering the bloodstream from an upper respiratory infection.
  • Haemophilus – caused by flu bacteria.
  • Listeria – caused by bacteria that is present in unpasteurized cheese, hot dogs and luncheon meats.

Obesity – excessive body fat that increases the risk of health problems.

  • Signs of Obesity – high body mass index (BMI) and an unhealthy body fat distribution. Having a body mass index over 30.
  • Symptoms of Obesity – there are no specific symptoms of obesity but can cause shortness of breath during exercise and fatigue.
  • Etiology of Obesity – contributed to metabolic factors, diet and physical activity. Can result from an energy imbalance, genes, metabolism, environment, culture and socioeconomic status.

Stroke – damage to the brain from an interruption of blood.

  • Signs of a Stroke – face dropping, arm weakness, confusion, double vision, vertigo and speech difficulty.
  • Symptoms of Stroke – numbness, weakness, tingling and/or vision loss/change.
  • Etiology of Stroke – people at risk include those with high blood pressure, high cholesterol, diabetes and those that smoke. Those with advanced aging and have had an immediate family member that had a stroke are also more susceptible.

Tuberculosis (TB) – an infectious bacterial disease that affects the lungs.

  • Signs of Tuberculosis – many of those infected with the bacteria don’t have signs. Others will experience coughing (sometimes blood-tinged), weight loss, night sweats and fever.
  • Symptoms of Tuberculosis – pain in the chest, cough, chills, fatigue, fever, loss of appetite, malaise, night sweats, sweating, loss of muscle, shortness of breath or swollen lymph nodes.
  • Etiology of Tuberculosis – caused by mycobacterium tuberculosis bacterium. It can spread through the air when a person with TB coughs, sneezes, spits, laughs or talks.

Alzheimer’s Disease – a progressive disease that destroys memory and other mental functions

  • Signs of Alzheimer’s Disease – aggression, agitation, difficulty with self-care, irritability, meaningless repetition of words, personality changes, lack of restraint or wandering and getting lost.
  • Symptoms of Alzheimer’s Disease – mental decline, difficulty thinking and understanding, confusion in the evening hours, delusions, disorientation, forgetfulness, making things up, mental confusion, difficulty concentrating, inability to do simple math or inability to recognize common things. Symptoms also include anger, apathy, general discontent, loneliness, mood swings, depression, paranoia, loss of appetite or restlessness.
  • Etiology of Alzheimer’s Disease – caused by brain cell death and the shrinking of the brain as the person has progressively fewer nerve cells and connections. Risk factors include aging, a family history and carrying certain genes.

Pneumonia – an infection of the lungs causing the lungs to be inflamed and the lungs to fill up with fluid.

  • Signs of Pneumonia – green phlegm, headache, muscle pain, confusion, purplish skin color.
  • Symptoms of Pneumonia – cough, fever, fast breathing, shortness of breath, shaking chills, chest pain, fast heartbeat, fatigue, weakness, nausea, vomiting, diarrhea, and sweating.
  • Etiology of Pneumonia – Can start with a bacteria, virus or fungal infection. Can be caused by many different types of bacteria, the most common is pneumococcal pneumonia. The bacteria and viruses that cause pneumonia are usually inhaled. They can be passed through coughing and sneezing or onto shared objects through touch.

Diagnostic Measures

Samples of body fluids can reveal evidence of particular microbe that is causing an illness. Other diagnostic measures include imaging scans and biopsies.

Blood Tests – the taking of blood from a patients’ vein by inserting a needle.

Urine Tests – the urination of a patient into a container.

Throat Swabs – use of a sterile swab to get a sample from the throat or other moist areas of the body.

Stool Sample – the collection of stool to observe for parasites and other organisms.

Spinal Tap – the collection of cerebrospinal fluid from a needle inserted between the bones of the lower spine.

Imaging Scans – use of X-ray, computerized tomography and magnetic resonance imaging

Biopsies – removal of a tiny sample of tissue from an internal organ for testing

Treatment Modalities

There are many different ways to treat diseases, conditions and injuries including medication, surgery, radiation therapy, education and medical devices.

Medication – a substance which has a physiological effect when ingested or introduced into the body.

Knowing what type of germ is causing an illness makes it easier for the physician to choose appropriate treatment.

  • Antibiotics – certain types of bacteria are susceptible to particular classes of antibiotics.
  • Antivirals – drugs developed to treat viruses including HIV, Herpes, Hepatitis and Influenza.
  • Antifungals – topical medications used to treat skin or nail infections caused by fungi.
  • Anti-Parasitics – for diseases caused by tiny parasites.

Surgery – the treatment of an injury or disorder of the body by incision or manipulation.

Radiation Therapy – the use of high-energy radiation to shrink tumors and kill cancer cells

Education & Therapy – conditions like obesity can be treated with a lifestyle change of diet and exercise.

Medical Devices – may include a stent or pacemaker to temporarily assist the body in maintaining healthy function.

Disease Incidence

A measure of disease that allows us to determine a person’s probability of being diagnosed with a specific disease in a given period of time. The number of newly diagnosed cases of a disease. An incidence rate is the number of new cases divided by the number of persons at risk.

Disease Prevalence

A measure of disease that allows us to determine a person’s likelihood of having a disease. The number of prevalent cases is the total number of cases of disease that exist in a population. A prevalence rate is the total number of cases existing in a population divided by the total population.

Disease Mortality

A term for death. A mortality rate is the number of deaths due to a disease divided by the total population.

  • Risk Factors for High Mortality Rates – genetics, cleanliness, vaccination rates and sexual activity.
  • Top 10 Causes of Death, according to the CDC – Heart Disease, Cancer, Chronic Lower Respiratory Disease, Stroke, Unintentional Injuries, Alzheimer’s Disease, Diabetes Mellitus, Pneumonia and Influenza, Kidney Disease, and Suicide.


Disease Morbidity

A term for illness. A person can have several co-morbidities at the same time. Prevalence is a measure to determine the level of morbidity in a population.

  • Risk Factors for High Morbidity Rates – smoking, obesity, level of physical activity, control of blood pressure and cholesterol.

Epidemics and Pandemics

An epidemic is when a disease spreads rapidly to many people whereas a pandemic is an outbreak of a disease across a whole country or world. A flu pandemic occurs when a new virus arises and humans have little to no immunity to it so everyone is at risk. The virus spreads easily throughout the population through airborne means including sneezing or coughing. A pandemic occurs when a virus causes serious illness worldwide.

Pandemics in history include the Spanish Flu in 1918 which killed over 40 million people, the Asian Flu in 1957 which killed over 1 million people, and the Hong Kong Flu in 1968 that killed over 1 million people.


Microbiology is the scientific study of microorganisms. Microorganisms are organisms too small to see with the naked eye. Some microorganisms that cause illness include bacteria, fungi and viruses. Microbiologists study these organisms using microscopes, genetics and culturing. Microscopes allow scientists the ability to magnify cells. Genetics helps scientists understand the evolutionary relationships between microbes and their habitat. Culturing describes the growing of microbes to test them and see what they like to eat or what conditions they can live in.

Cell structure

Humans are composed of molecules made from chemical elements including Carbon, Hydrogen, Oxygen and Nitrogen. The organization of these molecules create cells. Cells are the basic unit of structure and function in an organism. Cells only come from the replication of existing cells. A cell consists of three parts, the cell membrane, the nucleus and the cytoplasm. Included in the cell are many different structures including ribosomes, mitochondria, lysosomes and nucleolus.

  • Nucleus – the largest organelle, but not the brain. The nucleus contains the cell’s chromosomes.
  • Cell Membrane – a barrier separating every cell from its external environment. It regulates what passes into and out of the cell.
  • Cytoplasm – everything within the cell membrane that is not the nucleus. Cytosol + Organelles = Cytoplasm. Organelles carry out specific functions within cells. Cytosol holds the organelles in the Cytoplasm.
  • Ribosomes – are the site of protein synthesis in a cell and translates mRNA into proteins.
  • Mitochondria – found in the cytosol where energy from organic compounds is transferred to ATP.
  • Lysosomes – small spherical organelles that enclose hydrolytic enzymes within a single membrane.
  • Nucleolus – a small spherical structure in the nucleus of a cell during interphase.
  • Vacuole – stores food, water and waste in a cell
  • Endoplasmic Reticulum (ER) – a system of membranous tubules and sacs that act as an internal transport system, allowing molecules to move from one part of a cell to another.
  • Golgi Apparatus – the processing, packaging and secreting organelle of the cell.
  • Cytoskeleton – acts as a cell skeleton to maintain shape and size.
  • Cilia and Flagellate – structures that project from the cell to assist in movement.


The microbes in the body that make us sick. The immune system’s reaction to the foreign microbial that give us the symptoms. There are a few common pathogens that cause infectious diseases in humans, they include:

  • Streptococcus – mainly causes strip throat in humans. If untreated it can cause rheumatic fever of the heart valves and glomerulonephritis of the kidneys.
  • Neisseria – found in the mouth and female genital tract. The most common is gonorrhea which is transmitted through sexual activity. If untreated the infection can lead to gonococcal arthritis and pelvic inflammatory disease.


Organisms that are harmless to their host and can actually be beneficial. However, some non-pathogenic bacteria can inhibit the growth and reproduction of harmful bacteria.

  • Staphylococcus Epidermidis – a normal part of the skin that can cause superficial and systemic infections.
  • The Gram-Negative Bacilli – found in the intestinal tract that prevents overgrowth of optional pathogens. If they get out of the intestine, they can cause life-threatening disease. The most common disease caused by gram-negative bacilli is E. coli. E. coli can cause serious diarrhea and kidney damage. Other diseases caused by gram-negative bacilli include Salmonella and Shigella. Salmonella is caused by food poisoning and Shigella is caused by dysentery.
  • Bifidobacteria – part of the normal colon flora. Used in the food industry to make probiotic products.

Organisms and Microorganisms

An organism is any individual entity that exhibits the properties of life. Organisms are classified into multicellular animals, plants and fungi. Microorganisms are protists, bacteria and archaea. All types of organisms are capable of reproduction, growth and development, maintenance and stimuli. An organism is either a prokaryote or a eukaryote.

  • Prokaryote – includes bacteria and archaea.
  • Eukaryotic – characterized by the presence of a membrane-bound cell nucleus and containing organelles.
  • Protists – any eukaryotic organism that is not an animal, plant or fugus including algae and invertebrates.
  • Archaea – single-celled microorganisms that have no cell nucleus or any other membrane-bound organelles.

Infectious Agents

Infectious agents replicate in their hosts and fall into five groups including viruses, bacteria, fungi, protozoa and helminths.

  • Viruses – a biological agent that reproduces inside the cell of living hosts. The host cell is forced to produce thousands of identical copies of the virus.
  • Bacteria – tiny living beings. Bacteria comes in three shapes, spherical, rod shaped, and spiral. Bacteria is found everywhere.
  • Fungi – there are over 100,000 species of fungi and obtain nutrients from dead organic matter.
  • Protozoa – are non-phototrophic, one celled, eukaryotic microorganisms with no cell walls. Can cause disease in humans including:
    • Plasmodium – causes malaria
    • Trichomonas – causes sexually transmitted diseases
  • Helminths – large multicellular organisms commonly known as parasitic worms. The groups of parasitic helminths include:
    • Platyhelminths – flatworms
    • Acanthocephalans – thorny-headed worms
    • Cestodes – tapeworms
    • Trematodes – flukes
    • Nematodes – roundworms

Infectious Agents: Chain of Infection

Transmission occurs when the infectious agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission and then enters through an appropriate portal of entry to infect a susceptible host.

  • Reservoir – the habitat where the infection lives, grows and multiplies.
  • Portal of Exit – the path by which a pathogen leaves its host.
  • Modes of Transmission – transmission from its natural reservoir to a susceptible host.
    • Direct – the infectious agent is transferred from a reservoir to a susceptible host by direct contact or droplet spread.
    • Direct Contact – occurs through skin-to-skin contact, kissing and sexual intercourse.
      • Droplet Spread – occurs through sneezing, coughing or talking.
    • Indirect – the transfer of an infectious agent from a reservoir to a host by suspended air particles, inanimate objects or animate intermediaries.
      • Airborne – the infectious agent is carried by dust or droplet suspended in air.
      • Vehicleborne – occurs through food, water, blood and fomites
      • Vectorborne – mechanical or biologic including mosquitoes, fleas, and ticks.
  • Portal of Entry – refers to the manner in which a pathogen enters a susceptible host.
  • Host – the final link in the chain of infection. Susceptibility depends on genetic or constitutional factures including immunity.

Infectious Agents: Conditions for Growth

The growth requirements for microorganisms includes both chemical and physical characteristics. The chemical requirements for a microorganism to grow is first a supply of water for elements of oxygen. The microorganism is made up of carbon and obtain their energy and produce their nutrients from carbon dioxide. The other chemical elements include nitrogen for synthesis of proteins, amino acids, DNA and RNA. Lastly, a microorganism may need trace elements of iron, copper and zinc used for the synthesis of enzymes. The physical requirement for microorganisms to grow include temperature, pH, and osmotic pressure.

Bacteria grow in diverse conditions and are good at adapting to their environment. The conditions for growth of bacteria include temperature, moisture, pH and environmental oxygen. Most disease-causing bacteria thrive in warm temperature including the human body. Bacteria needs water to grow. The pH of an environment or its acidity or alkalinity is important for bacterial growth. Most bacteria prefer to grow in conditions with a neutral pH. Lastly, the presence of oxygen can greatly affect growth of bacteria. Bacteria likes to grow in oxygen-rich environments.

Does Physiology and Microbiology interest you? Want to become a medical assistant? The Medical Assisting program at Daymar College is designed to prepare current and future employees for the fast-paced changes encountered in the health care industry, and to help develop training, skills and attitudes necessary to excel in medical assisting. Contact us to learn more about a great opportunity to become a medical assistant.