DTW GED PREP

Body Systems

The human body is made up of organ systems that work together to carry out all the functions needed for life. Each system has specialized organs and functions.

Circulatory System: Transports nutrients and oxygen to cells, removes waste.

Digestive System: Breaks down food into nutrients the body can use.

Respiratory System: Brings in oxygen and removes carbon dioxide. etc.

Interaction Between Body Systems

Most tasks in the body require two or more organ systems to work together. For example: The respiratory, digestive, and circulatory systems work together during cellular respiration. The respiratory system brings oxygen into the lungs. The digestive system breaks food into nutrients such as glucose. The circulatory system transports oxygen and glucose to cells and carries carbon dioxide waste back to the lungs. Another example of body system teamwork is movement: The muscular, skeletal, and nervous systems cooperate to allow you to walk, run, or lift objects. The nervous system sends signals. The skeletal system provides structure and joints. The muscular system contracts to move bones.

Homeostasis

Homeostasis is the body’s ability to maintain a stable internal environment, even when external conditions change. Humans can live in a wide range of environments because our bodies have feedback controls that constantly monitor and adjust conditions. Even small events, like a scrape on your arm, trigger responses to restore balance and maintain homeostasis.

Types of Feedback Loops

There are two main types of feedback loops:

1.  Negative Feedback Slows down or stops a process when it is no longer needed.

Example: Your stomach stops churning when you are not eating.

2. Positive Feedback Encourages or amplifies a physiological process.

Example: The production of the digestive enzyme pepsin.

Your stomach secretes inactive pepsinogen. Once some pepsin forms, it helps convert more pepsinogen to pepsin in a rapid cascade, ensuring enough enzyme is available to digest proteins.

This diagram should illustrate both negative and positive feedback examples.

Effects of External Environments

Your body also uses homeostatic feedback to respond to external changes like temperature. Example: Overheating. Standing in the hot sun raises body temperature. Skin receptors sense the change and send messages to the brain. The brain signals sweat glands to release sweat. Sweating cools the body, reducing temperature and restoring homeostasis.

 Example: Cold Exposure, going outside without a coat on a cold day trigger:

Hair follicles on arms tighten and stand up to trap heat. Muscles shiver to generate heat through movement. These actions help maintain a normal 98.6 °F (37 °C) body temperature. Failure of these responses can lead to hypothermia, a dangerous drop in body temperature.

Nutrients and Homeostasis

Your body’s ability to maintain homeostasis relies on having the right nutrients to fuel chemical reactions and body processes.

Functions of the food nutrients above:

• Proteins: Build and repair tissues (found in meat, beans).
• Carbohydrates: Provide quick energy (bread, fruits).
• Fats: Store energy, insulate (oils, nuts).
• Vitamins: Regulate body processes (vegetables, fruits).
• Minerals: Build bones, carry oxygen (dairy, leafy greens).
• Water: Transports nutrients and wastes, regulates temperature.

Eating the right amount of each nutrient is essential for health.

Deficiencies can cause health problems. Excesses can also be harmful.

Too much protein can produce toxins that stress the kidneys. Too much fat can lead to obesity. Reading Food Labels You can find information about nutrients in packaged foods by reading nutrition labels.

This illustration should point out important details like:

Serving size, Number of calories per serving, Amounts of proteins, carbohydrates, fats, Vitamins and minerals Learning to read food labels helps you make healthy choices and maintain a balanced diet.

Disease and Pathogens

The stability of the human body, known as homeostasis, can be disrupted by many factors, including disease. Diseases are often caused by harmful agents known as pathogens. Pathogens are microorganisms or viruses that invade the body and cause illness.

Types of Pathogens and Their Transmission

Pathogens can enter the body through various routes and spread from person to person or through environmental contact. The five most common modes of pathogen transmission include direct contact, airborne droplets, contaminated food or water, vector organisms (like mosquitoes), and contaminated surfaces. Example: Airborne droplets: nfluenza virus it can be spread through coughing or sneezing

Prevention of Disease

Many diseases can be prevented by adopting simple health and hygiene practices. These include: Washing hands regularly with soap and water. Covering the mouth and nose when coughing or sneezing. Preparing and storing food safely. Avoiding contact with sick individuals when possible.

One of the most effective ways to prevent certain diseases is through immunization. Vaccines prepare the body’s immune system to recognize and fight specific pathogens. They allow a person to develop immunity without experiencing the illness itself.

Effects of Disease on Populations

Infectious diseases have not only affected individuals but have also dramatically shaped human history. Before vaccines were available, outbreaks of viral and bacterial diseases caused widespread suffering and death.

One historical example is the impact of European colonization on Native American populations. Between the 15th and 18th centuries, diseases such as smallpox, measles, and influenza were introduced to the Americas. Lacking immunity, many Indigenous populations experienced mortality rates as high as 80%. These population collapses significantly altered the balance of power and made conquest easier for colonizers.

> 📉 Diagram Placeholder: “Historical Population Decline Due to Disease (15th–18th Century)”

(Graph showing steep decline in Indigenous populations due to outbreaks)

Even today, epidemics and pandemics can cause massive societal and demographic shifts. Uncontrolled disease outbreaks can threaten public health, destabilize economies, and even contribute to species extinction if vulnerable populations are affected.