Disease and Body Responses

Disease

• Our world is full of all kinds of microorganisms, called pathogens, that cause disease

• Diseases can be mildly uncomfortable, hinder normal functioning or even cause death

Types of Pathogens

• Viruses

• Bacteria

• Parasites

Viral Diseases

• Common Cold

• Influenza (Flu)

• West Nile Virus

• Chicken Pox

• HIV

• Can you think of any others?

Bacterial Diseases

• Cholera

• Tetanus

• Pneumonia

• Tuberculosis

• Bubonic Plague

• Lyme Disease

• Others?

Diseases Caused By Parasites

• Malaria

• Dysentery

• Typhus

• Chagas Disease

• Others?

Disease

• Diseases harm our bodies by disrupting homeostasis

• What is homeostasis?

Homeostasis

• Homeostasis is the state of balance in the body

• Your body works to maintain homeostasis by responding to various stimuli

Stimuli

• Stimuli can come in both internal and external forms

• An internal stimulus is one that comes from within the body while an external stimulus comes from the environment

Examples of Stimuli

• Internal– Hunger/Thirst– pH Levels– Electrolyte

concentrations– Blood sugar levels

• External– A pinch on the arm– Temperature– Atmospheric oxygen

levels– Toxins– Light– Pathogens entering

the body (Diseases)

Let’s Look at an Example

• Your body has a certain desired amount of glucose that it needs in its system at any given time

• If your body detects an imbalance in these blood glucose levels, an organ called the pancreas responds by releasing two hormones, insulin and glucagon, to bring it back to the proper level

Example Cont.

• If for any reason the pancreas is unable to produce enough of either of these hormones, diabetes can result

Ways the Human Body Responds to Infection

• Runny Nose

• Fatigue

• Fever

• Nausea

• Vomiting

Runny Nose• Normally, your nose

makes mucus to keep things like dirt, pollen and germs out of your lungs

• When you’re sick, you get a runny nose because your body is trying to keep more pathogens from getting in by making a lot more mucus than usual

Fatigue• Often when an infection

sets in, the body wants to conserve as much energy as possible

• The feeling of fatigue makes you want to rest and sleep, reserving energy for your body to fight off pathogens, the disease-causing agents

Fever• Most disease-causing

pathogens function very well at normal body temperatures

• By increasing your body temperature with a fever, your body is trying to hinder the pathogen’s reproduction

Nausea and Vomiting

• Sometimes sickness is caused by eating contaminated food (also spoiled food and toxins). To keep you from ingesting more of what could be causing your illness, you feel nausea.

• Vomiting is an attempt to get rid of the source of your illness

Anatomy of Vomiting

• Increased salivation to protect the enamel coating of your teeth from stomach acids.

• The middle of your small intestine contracts, followed by your abdominal muscles which pushes the stomach contents into your esophagus.

• Increased heart rate and sweating occurs.

• The brain has a center for controlling your body’s reaction.

Other Body Responses

• Our bodies respond to more than just diseases. Other common responses:– Shortness of breath– Changes in pulse rate– Shivering– Feeling hungry

• What is each of these responses there for? What does it accomplish?

Other body responses• Think about what happens when you

exercise• Muscles need oxygen, and they make CO2

as waste. When they are being worked, the levels

of oxygen and CO2 in the bloodstream are thrown off balance

• To get more oxygen to the muscles and carry away the CO2, the brain knows to increase breathing and pulse rates

Other Body Responses

• During heart failure, the heart isn’t pumping enough blood

• To compensate, the body response is:– Blood vessels constrict– Blood pressure increases– Tissues retain more water and sodium– Heart enlarges