In the absence of leptin, you might never feel satisfied from a meal. The result of either problem is overeating, which may result in obesity and, in uncorrected, diabetes.
Calcium ions are crucial for proper nerve and muscle function. Your thyroid and parathyroid glands regulate blood calcium levels by their effect on of calcium homeostasis. The thyroid gland causes a decrease in blood calcium levels, while the parathyroid gland helps increase calcium in the blood.
If calcium levels drop too low, this results in hypocalcemia, which can cause seizures, muscle spasms or an abnormal heart rhythm. When this happens, you could experience nausea, vomiting, abdominal pain, constipation, weakness, confusion, excessive thirst or loss of appetite. Water balance is essential for proper functioning of nerves and many organs.
The brain detects the amount of water in the blood and the kidney senses your blood pressure, which is determined to some degree by the volume of your blood. When water levels in the body are low, you can become dehydrated. These substances are typically packaged into membrane-bound vesicles within the cell. When the vesicle membrane fuses with the cell membrane, the vesicle releases it contents into the interstitial fluid. The vesicle membrane then becomes part of the cell membrane.
Cells of the stomach and pancreas produce and secrete digestive enzymes through exocytosis Figure 8. Endocrine cells produce and secrete hormones that are sent throughout the body, and certain immune cells produce and secrete large amounts of histamine, a chemical important for immune responses. To ensure that you understand the material in this chapter, you should review the meanings of the bold terms in the following summary and ask yourself how they relate to the topics in the chapter.
A solution is a homogeneous mixture. The major component is the solvent , while the minor component is the solute.
Solutions can have any phase; for example, an alloy is a solid solution. Solutes are soluble or insoluble , meaning they dissolve or do not dissolve in a particular solvent. The terms miscible and immiscible , instead of soluble and insoluble, are used for liquid solutes and solvents.
The statement like dissolves like is a useful guide to predicting whether a solute will dissolve in a given solvent. Dissolving occurs by solvation , the process in which particles of a solvent surround the individual particles of a solute, separating them to make a solution.
For water solutions, the word hydration is used. If the solute is molecular, it dissolves into individual molecules. If the solute is ionic, the individual ions separate from each other, forming a solution that conducts electricity. Such solutions are called electrolytes.
If the dissociation of ions is complete, the solution is a strong electrolyte. If the dissociation is only partial, the solution is a weak electrolyte.
Solutions of molecules do not conduct electricity and are called nonelectrolytes. The amount of solute in a solution is represented by the concentration of the solution. The maximum amount of solute that will dissolve in a given amount of solvent is called the solubility of the solute. Such solutions are saturated. Solutions that have less than the maximum amount are unsaturated. Most solutions are unsaturated, and there are various ways of stating their concentrations.
Parts per million ppm and parts per billion ppb are used to describe very small concentrations of a solute. Molarity , defined as the number of moles of solute per liter of solution, is a common concentration unit in the chemistry laboratory. Equivalents express concentrations in terms of moles of charge on ions.
When a solution is diluted, we use the fact that the amount of solute remains constant to be able to determine the volume or concentration of the final diluted solution. Solutions of known concentration can be prepared either by dissolving a known mass of solute in a solvent and diluting to a desired final volume or by diluting the appropriate volume of a more concentrated solution a stock solution to the desired final volume. The cell membrane provides a barrier around the cell, separating its internal components from the extracellular environment.
The cell membrane is selectively permeable, allowing only a limited number of materials to diffuse through its lipid bilayer. All materials that cross the membrane do so using passive non energy-requiring or active energy-requiring transport processes. During passive transport, materials move by simple diffusion or by facilitated diffusion through the membrane, down their concentration gradient.
Water passes through the membrane in a diffusion process called osmosis. During active transport, energy is expended to assist material movement across the membrane in a direction against their concentration gradient.
Active transport may take place with the help of protein pumps or through the use of vesicles. What materials can easily diffuse through the lipid bilayer, and why?
Why is receptor-mediated endocytosis said to be more selective than phagocytosis or pinocytosis? What do osmosis, diffusion, filtration, and the movement of ions away from like charge all have in common?
In what way do they differ? Which of the representations best corresponds to a 1 M aqueous solution of each compound? Justify your answers. Which of the representations shown in Problem 1 best corresponds to a 1 M aqueous solution of each compound?
Would you expect a 1. Why or why not? An alternative way to define the concentration of a solution is molality , abbreviated m. Molality is defined as the number of moles of solute in 1 kg of solvent. How is this different from molarity? Would you expect a 1 M solution of sucrose to be more or less concentrated than a 1 m solution of sucrose? Explain your answer.
What are the advantages of using solutions for quantitative calculations? If the amount of a substance required for a reaction is too small to be weighed accurately, the use of a solution of the substance, in which the solute is dispersed in a much larger mass of solvent, allows chemists to measure the quantity of the substance more accurately. Calculate the number of grams of solute in 1. If all solutions contain the same solute, which solution contains the greater mass of solute?
Complete the following table for mL of solution. What is the concentration of each species present in the following aqueous solutions?
What is the molar concentration of each solution? Give the concentration of each reactant in the following equations, assuming An experiment required A stock solution of Na 2 CrO 4 containing Describe how to prepare Calcium hypochlorite [Ca OCl 2 ] is an effective disinfectant for clothing and bedding.
If a solution has a Ca OCl 2 concentration of 3. Phenol C 6 H 5 OH is often used as an antiseptic in mouthwashes and throat lozenges. If a mouthwash has a phenol concentration of 1. If a tablet containing mg of caffeine C 8 H 10 N 4 O 2 is dissolved in water to give A certain drug label carries instructions to add If a patient has a prescribed dose of The major component of the solution is called the solvent , and the minor component s are called the solute. When a gaseous or solid material dissolves in a liquid, the gas or solid material is called the solute.
When two liquids dissolve in each other, the major component is called the solvent and the minor component is called the solute. Many chemical reactions are carried out in solutions, and solutions are also closely related to our everyday lives.
The air we breathe, the liquids we drink, and the fluids in our body are all solutions. Furthermore, we are surrounded by solutions such as the air and waters in rivers, lakes and oceans.
Back to the Top Types of Solutions Material exists in three states: solid, liquid, and gas. Solutions also exist in all these states: Gaseous mixtures are usually homogeneous and are commonly gas-gas solutions. For quantitative treatment of this type of solutions, we will devote a unit to gases. The atmosphere is a gaseous solution that consists of nitrogen, oxygen, argon, carbon dioxide, water, methane, and some other minor components.
Some of these components, such as water, oxygen, and carbon dioxide may vary in concentration in different locations on the Earth depending on factors such as temperature and altitude. When molecules of gas, solid or liquid are dispersed and mixed with those of liquid, the homogeneous uniform states are called liquid solutions.
Solids, liquids and gases dissolve in a liquid solvent to form liquid solutions. In this chapter, most of the chemistry that we will discuss occurs in liquid solutions where water is the solvent. Many alloys, ceramics, and polymer blends are solid solutions. Within a certain range, copper and zinc dissolve in each other and harden to give solid solutions called brass. Silver, gold, and copper form many different alloys with unique colors and appearances.
Alloys and other solid solutions are important in the world of materials chemistry. For example: In special circumstances, a solution may be supersaturated.
Asked for: amount of solute in moles Strategy: 1 Rearrange the equation above to solve for the desired unit, in this case for moles. Solution: 1 Rearrange the equation above to solve for moles. Example Molarity Calculation The solution in Figure 7. Given: mass of solute and volume of solution Asked for: concentration M Strategy: 1. To calculate Molarity, we need to express: the mass in the form of moles the volume in the form of Liters Plug both into the equation above and calculate Solution: Converting the mass into moles.
Convert the volume into Liters 3. Plug values into the Molarity equation:. Example of Dilution Calculations What volume of a 3. Given: volume and molarity of dilute solution, and molarity of stock solution Asked for: volume of stock solution Strategy and Solution: For Dilution problems, as long as you know 3 of the variables, you can solve for the 4th variable.
Start by rearranging the equation to solve for the variable that you want to find. In this case, you want to find the volume of the stock solution, V s 2. Example 1 What are the concentrations of all ionic species derived from the solutes in these aqueous solutions?
Solution: 1. Maintaining Homeostasis The process in which organ systems work to maintain a stable internal environment is called homeostasis. Here are just three of the many ways that human organ systems help the body maintain homeostasis: Respiratory system: A high concentration of carbon dioxide in the blood triggers faster breathing. The lungs exhale more frequently, which removes carbon dioxide from the body more quickly.
Excretory system: A low level of water in the blood triggers retention of water by the kidneys. The kidneys produce more concentrated urine, so less water is lost from the body. Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas.
Insulin is a hormone that helps cells absorb sugar from the blood. Positive Feedback Some processes in the body are regulated by positive feedback. Failure of Homeostasis Many homeostatic mechanisms such as these work continuously to maintain stable conditions in the human body. Summary All of the organ systems of the body work together to maintain homeostasis of the organism.
If homeostasis fails, death or disease may result. Review What is homeostasis? Describe how one of the human organ systems helps maintain homeostasis. A house has several systems, such as the electrical system, plumbing system, and heating and cooling system.
In what ways are the systems of a house similar to human body systems? For example, older people may have a harder time regulating their body temperature. This is one reason they are more likely than younger people to develop heat stroke and other diseases caused by the body overheating.
Older people also have a harder time fighting off many infectious diseases and cancer. Although virtually all diseases involve homeostatic imbalances in some way, there are many different underlying causes of disease. For example, some diseases are caused by pathogens, whereas others are not. Pathogens are agents — usually microorganisms — that cause disease. Diseases caused by pathogens are called infectious, or communicable, diseases because pathogens can spread the diseases by moving from host to host.
Examples of infectious diseases include the common cold, influenza, chickenpox, cholera, and malaria. Some infectious diseases are spread only or mainly through sexual contact.
These diseases are called sexually transmitted infections STIs and include gonorrhea and syphilis see the concept of Sexually Transmitted Infections to learn more.
Diseases that are not caused by pathogens are called noninfectious diseases. They are also called non-communicable diseases because they do not spread from person to person. Examples of noninfectious diseases include diabetes, most types of cancer, and cardiovascular diseases. There are numerous possible causes of noninfectious diseases. They include inherited mutations, exposure to environmental toxins such as air pollution, and unhealthy lifestyle choices such as overeating or smoking.
Most infectious diseases are also acute diseases. An acute disease is a short-term disease. After a person gets sick, an acute disease either runs its course with or without medical intervention until the person gets better, or the disease leads to the death of the infected individual.
Many noninfectious diseases are chronic diseases. Chronic disease is a long-term or even lifelong disease. For example, people who develop type 1 diabetes have the disease for life as do most people who develop cardiovascular diseases. Some noninfectious diseases, such as cancer, may be cured or they may be kept under control as chronic diseases with medications. Certain infectious diseases are also chronic rather than acute diseases because they are caused by pathogens that the body cannot eliminate.
Examples are the viruses that cause herpes and AIDS. Some infectious diseases spread through a population from time to time as large-scale disease outbreaks called epidemics, but are not always present in the population, at least not at high levels.
Such diseases are called epidemic diseases. An example is the flu influenza. In the United States, flu spreads through the population at a certain time each year generally, from November through April , but is not commonly found at other times of the year.
Some epidemic diseases lead to pandemics. A pandemic is an epidemic that spreads across multiple populations, often across continents or even worldwide. Throughout human history, there have been many pandemics of infectious diseases. One of the most devastating pandemics was the Black Death bubonic plague pandemic that spread throughout Europe and much of Asia in the mids.
In this pandemic, an estimated 75 million people died. More recent pandemics include influenza pandemics that occurred in and see Explore More below. By April , it killed 3. Some diseases are always present in a population. Such diseases are referred to as endemic diseases.
0コメント