Finals Flashcards
Understand the major functions of cells and the difference between viruses, bacteria
Bacteria and viruses are both microbes. Bacteria are alive, but Viruses are not. Bacteria can be seen with the naked eye when piled up on one another, and viruses cannot. Viruses enter a cell, take over its mechanism, and make it do things it should not. Some microbes are pathogenic and have molecular tools that can cause disease by attaching to cells and cloaking themselves from the immune system. But most are not. Our bodies contain many microbes.
Your body is comprised of various kinds of cells: muscle cells, lung cells, kidney cells, and urinary tract cells. They all function differently and allow different things to flow in and out.
Stem cells, the architects of regeneration, can grow into new cells, ensuring that our body is constantly being renewed.
Cells can become damaged enough to die, and when the outer layer of a cell membrane is damaged, the contents of the cell leak out.
Explain protein synthesis and the role of DNA, mRNA, tRNA, ribosomes
The chromosome contains long strands of DNA, tightly packaged around proteins called histones. Within the DNA are sections called genes. These genes contain the instructions for making proteins. When a gene is switched on, an enzyme called RNA polymerase attaches to the start of the gene.
It moves along the DNA, making a strand of messenger RNA out of free bases in the nucleus. The DNA code determines the order in which the free bases are added to the messenger RNA, a process called transcription. Before the messenger RNA can be used as a template for the production of proteins, it needs to be processed.
This involves removing and adding sections of RNA. The messenger RNA then moves out of the nucleus, into the cytoplasm. Protein factories in the cytoplasm called ribosomes bind to the messenger RNA. The ribosome reads the code in the messenger RNA to produce a chain made up of amino acids.
There are 20 different types of amino acids. Transfer RNA molecules carry the amino acids to the ribosome. The messenger RNA is read three bases at a time. As each triplet is read, a transfer RNA delivers the corresponding amino acid.
This is added to a growing chain of amino acids. Once the last amino acid has been added, the chain folds into a complex 3D shape to form the protein.
And proteins are important because they make up every basic function of your body, such as the immune system.
Explain how biological and genetic factors can influence our response to environmental hazards
Individual point mutations in our DNA molecules make us different from one another. This comes from the copies of chromosomes from the pairs created by your parents’ sperm and egg. These changes can change the functions of various proteins in our bodies. Sometimes, that change is for the better, and other times, it can be for the worse. For example, some Europeans have a gene function that makes them more susceptible to being addicted to opioids.
Explain the role of the microbiome and its role in disease prevention
Bacteria and viruses are both microbes. Bacteria and Viruses enter a cell, take over its mechanism, and make it do things it should not. Some microbes are pathogenic and have molecular tools that can cause disease by attaching to cells and cloaking themselves from the immune system. Frank pathogens, such as the flu, can cause diseases in even the healthiest person. Opportunistic pathogens cause disease when they move to a particular area of the body. Ecoli can exist in your intestines and not make you sick, but if it is in your urinary tract, it can give you an infection. Most microbes are non-pathogenic and exist in our bodies. Our goal in public health is to promote good pathogens and try to demote destructive pathogens.
Microbes have different properties that cause them to thrive or die. For example, some microbes die at certain temperatures, such as when we cook food. Some die when we use hand sanitizer and soap; some cannot survive UV rays. Microbes may thrive in environments like insects where they can make the insect a vector to attack other beings. Others thrive in the water, such as cholera or salmonella. Understanding microbes and how they thrive or die can help us prevent the spread of disease.
Explain how environmental factors influence genetic expression (i.e., epigenetics)
External exposures can change our genetics; chemicals, diet, and stress can alter genetic modifications and be passed down to future generations. One example would be how some Europeans are immune to the Black Plague because their ancestors caught it and became immune, and they, therefore, have immunity to some other diseases.
Explain various types of genetic mutations that can occur
Genotypic change- Change in the genetic sequence of an organism. These changes are only noticeable if they cause a change in phenotype, known as a change in function.
Non-noticeable Mutations are mutations that do not make a difference.
Mutations are not all bad. They are the raw materials of evolution.
Explain the difference between genotoxic versus non-genotoxic carcinogens.
Genotoxic carcinogens, otherwise known as mutagens, can interact with and alter DNA. They can also alter point mutations that can lead to changes in the genetic sequence or cause chromosomal aberrations that damage the structure of chromosomes.
Nongenotoxic carcinogens are thought to act by increasing the rate of cell division. If you have more cell division in the presence of a chemical than you have without it, you’re going to have more of those replication errors and more chances for, just randomly, a bad mutation to occur that can move a cell along. So that’s how something that isn’t directly causing mutations can still increase the rate of mutation and increase the likelihood of cancer.
Know the three cancer types in the US that cause the highest mortality.
Lung Cancer, Colon Cancer, Pancreatic Cancer
Explain the difference between innate versus adaptive immunity
Innate immunity doesn’t care what the invader is. It’s ready to go. The first part is the physical barriers that keep things from entering your body. And that’s your skin, the mucous membranes of the inside of your mouth and inside of your nose, and even the very acidic conditions of your stomach are part of protecting your body. Not a lot of things can survive the acidic conditions in your stomach. But if cells get in, there are specific kinds of cells in the innate immunity system that can directly attack these invaders
Adaptive immunity is the immunity that is made for you to deal with something that you’ve seen before. It allows your body to build up a defense for some kind of an organism, some kind of invader, that might come along again. Adaptive immune system detects specific molecules on the surface of cells. And these molecules are usually proteins, but they can be other kinds of molecules as well. And what happens is the immune system distinguishes between itsef and antigens that may be coming from a virus or bacteria.
Explain the antibody/antigen reactions and the types of defense reactions they trigger
An antigen is a substance that can provoke an immune response. Antigens may be found on things like fungi, bacteria, other foreign bodies, and even self-cells. Different types of cells work together to recognize and neutralize antigens carrying invaders.
Antibodies are in your body’s makeup by the millions. Antibodies are proteins that are coded in genes. Each one of these antibodies has a specific binding domain. And that binding domain would react with some particular antigen. Each immune cell makes only one antibody. So you’ve got cells making antibodies, but they’re making just one. The important thing about these antibodies is that they recognize a specific antigen with great specificity.
Explain how vaccines use the body’s natural immune system to protect from diseases.
The body is exposed to a weakened form, usually of some pathogen, and the innate immune system takes care of things. But we’re really trying to go up along that top side and get the body to form those memory cells for antibodies that react to antigens on that pathogen. So we’re making a memory of exposure to that particular organism so that, when it’s reencountered, the body can mount a faster and stronger response.
Explain the importance of “herd immunity” in protecting a population from the spread of disease.
What herd immunity does is put, in the middle of the population, people who will not be able to transmit the disease–that is, they have been made immune to that disease. So, on the bottom, you can see how the presence of people immune to a disease, made immune to that disease by vaccines, can prevent transmission. So you see that a transmitting case comes in contact with a person who has been immunized and is immune. That person essentially stops that transmission route. Some people may not be vaccinated because of compromised immune systems or other medical conditions. But if we have our herd immunity high enough, if we have enough people vaccinated, those people are protected, too. Let’s look at this just one more time.
Describe absorption
Absorption: All pollutants must cross a cell membrane to enter the body. The membrane barrier influences which molecules can cross through. Uncharged hydrophobic molecules can cross, but most charged or polar molecules cannot. Protein channels and pores facilitate the absorption of some materials your body wants to absorb that it would typically not be able to absorb.
Passive diffusion occurs when a material dissolves and crosses the membrane; no energy is needed. All it has to do is flow following what’s called its concentration gradient, which goes from an area of high concentration to an area of low concentration. Three things will determine whether passive diffusion is the way in which a chemical enters the body: membrane. No en size, hydrophobicity, and ionization (charge). Different parts of your body are more polar or non-polar. Blood-more polar Fats-Less polar, if we know about a pollutant solvability, it can help us determine where it will end up in the body.
Facilitated Diffusion-uses protein pores or carrier proteins to help a molecule get across the cell membrane. So things are going to move from where the concentration is high to where the concentration is low. These pores are very specific for the molecule that it is helping across.
Active Transport- the cell putting in energy to move a molecule from outside to inside or inside to outside. Normally, it does it against a concentration gradient, so energy is needed. One example is pottasium.
Describe Metabolism
Metabolism, also called biotransformation, is the enzymatic alteration of a molecule’s chemical structure. Biotransformation is usually assumed to make molecules easier to excrete. There are two primary systems of elimination.
Phase 1 reactions expose or add polar groups. Polar groups make the substrate more likely to be dissolved in water. A family of enzymes that can react with many different chemicals. Add polar groups, increase urine excretion, or reactive groups to set up for phase 2. These chemicals are inducible. Introduction to the substrate can increase enzyme production.
Phase 2 reactions conjuction make bigger and less reactive. Adding another molecule to the molecule we are trying to excrete to influence how it will be excreted. Increase biliary or urinary excretion. Enzymes are inducible.
Describe Distribution
Important membrane barriers:
GI Tract organs have different PHs that can influence the absorption of a chemical.
Skin: everything that is absorbed is through passive diffusion. Skin thickness and the amount of hair can influence how things are absorbed in the body as well.
Lungs: Gases and vapors are materials that are truly dissolved in the air. They are primarily absorbed through passive diffusion. Think of Oxygen and carbon dioxide. Aerosols and particles are carried along in the air. The size determines where in the respiratory tract it will be deposited.
Materials enter the body and are distributed throughout it by the blood. As the blood passes through the various organs and tissues, sometimes the chemical can stay in a certain organ or tissue, depending on what is in the organ and what is in the material.
First-pass effect—For every bit of material absorbed from your GI tract, your body has a special circulatory system that takes everything to your liver. The liver has extensive metabolic capacity to change the chemical form of a molecule, which can also change its activity.
Describe Excretion
Sometimes, it is called elimination. Molecules are leaving the body. Sometimes, parts of food are not used as nutrients, drugs, etc. The majority of materials go through the kidney and out through urine. They are very soluble, so they can be carried through blood, into plasma, and into urine. Other material is carried from the liver to the GI tract and then excreted. Some material is eliminated through the lungs. This is going to be all passive diffusion. Like breathalizer test the concentration of ethanol in alcohol you drank because it is being breathed out when blood passes the alveoli. Some chemicals leave through hair, nails, tears, and sweat. The rate at which something can exit the body will have an effect on its reactions in the body.
Discuss pros and cons of toxicology and epidemiology in determining toxicity
Toxicology studies the adverse responses in biological systems caused by chemical or physical agents. Its two basic functions are:
Assess the likelihood of the occurrence of adverse effects.
Study the nature and mechanisms of adverse effects.
Pros: Well-controlled experiments, controlled doses, and no confounding exposures. It gives us a perspective. For example, pesticides are tested before being exposed to human environments.
Cons: Generalizations across species, high dose to low dose extrapolation for animals being tested actual dose to humans. Definition of response to a toxic exposure.
Differentiate between acute and chronic toxicity
Acute toxicity is things that happen in a very short amount of time. This is most like poisoning a single dose.
Subchronic toxicity is a toxicity that might occur with exposures in humans that last from weeks to months to a year or so.
Chronic toxicity is a toxicity that occurs because of very long-term exposure over many, many years, or even a lifetime.
Explain how different people may handle toxicants differently based on enzymatic makeup
Some people will have a high-level response to toxins, and others will have a low-level response. There are genetic differences in metabolizing toxins across populations. This can be due to nutritional status, existing diseases, prior exposures, and a variety of other things. However, the notion is that there is variability in the population.
Define key toxicology terms and concepts (e.g., NOAEL, LOAEL, LD50, RfD, slope factor, etc.)
LD50 is a standard test of acute toxicity. It is the dose that is required to be lethal.
LC50 is the lethal concentration in ppm or mass/volume lethal to 50% of test animals.
NOAEL: no observed adverse effect level, the highest dose administered for which no harmful effects are observed. The EPA uses this to establish a referenced dose (RfD).
RfD- Reference dose, which is an estimate of the daily oral dose of a chemical that is likely to be without appreciable risk for an individual over a lifetime of exposure.
Characterize the primary routes of human exposure (oral, inhalation, dermal)
Dermal exposure: through the skin. Everything that is absorbed is through passive diffusion. Skin thickness and the amount of hair can influence how things are absorbed in the body as well.
Ingestion is done through the mouth, through the GI tract. Organs in the GI system have different pHs that can influence the absorption of a chemical.
Inhalation-by breathing into the lungs. Gases and vapors are materials that are truly dissolved in the air. They are primarily absorbed through passive diffusion. Think of Oxygen and carbon dioxide. Aerosols and particles are carried along in the air. The size determines where in the respiratory tract it will be deposited.
Explain the role of liver in breaking down food, microbes and chemical toxicants
The liver has extensive metabolic capacity to change a molecule’s chemical form, which can also change its activity. Following gastrointestinal absorption, compounds are carried to the liver by blood and filtered. Thus, excretion into the bile is potentially a rapid and efficient process. Toxicants secreted with the bile enter the gastrointestinal tract and, unless reabsorbed, are secreted with the feces.
