The surprising reason you feel awful when you're sick - Marco A. Sotomayor

Summary

The flu’s unpleasant symptoms, like fever, body aches, and fatigue, are actually caused by the body’s immune response. When a virus infects you, macrophages attack the invaders and release cytokines to recruit more immune cells. These cytokines trigger symptoms like fever and sleepiness, which may help the body fight off the infection. The body’s discomfort is a result of its defense mechanisms at work, not the virus itself. While autoimmune diseases occur when the body mistakenly attacks itself, the immune system is usually finely tuned to protect us, ensuring survival for generations.

Takeaways

• 😀 The flu begins with common symptoms like a sore throat, cough, muscle aches, irritability, and loss of appetite.
• 😀 The flu virus infects cells in the body, but the body’s immune response plays a key role in the symptoms you experience.
• 😀 Macrophages are the first line of defense, attacking and destroying viruses and infected cells.
• 😀 Cytokines are proteins released by macrophages that help organize the immune response and recruit more virus-fighting cells.
• 😀 If the infection spreads, the immune system coordinates with the brain to launch a stronger attack, triggering flu-like symptoms.
• 😀 Fever, aches, and sleepiness occur as the immune system increases the production of cytokines, which communicate with the brain.
• 😀 The hypothalamus is responsible for regulating temperature, hunger, and sleep during illness, triggering symptoms to help fight infection.
• 😀 The rise in body temperature may slow down bacteria and aid in immune function, while loss of appetite helps deprive bacteria of iron.
• 😀 Mild dehydration from reduced thirst may decrease pathogen transmission through bodily fluids like coughs or sneezes.
• 😀 Irritability, sadness, and confusion are common during illness, caused by cytokines affecting neurotransmitter activity in the brain.
• 😀 While the immune system is mostly helpful, autoimmune diseases occur when the body attacks itself, mistaking healthy cells for threats.

Q & A

What is the first sign that you have the flu?

The first sign of the flu is often a tickle in your throat, which quickly turns into a cough. This is followed by muscle aches, irritability, and a loss of appetite.

Why does your body experience symptoms like fever, aches, and fatigue when you get sick?

These symptoms are caused by your immune system's response to infection. Cytokines, released by immune cells like macrophages, trigger processes in your brain that cause fever, pain, sleepiness, and loss of appetite as part of the defense mechanism.

How does the immune system defend the body against viruses like the flu?

When a virus infects the body, macrophages are the first immune cells to attack, seeking out and destroying the virus. They then release cytokines to recruit more immune cells, coordinating a stronger defense against the infection.

What role does the hypothalamus play when you are sick?

The hypothalamus controls various bodily functions, including temperature regulation, sleep, and hunger. During an infection, it receives signals from cytokines and produces prostaglandin E2, which leads to fever, fatigue, and a decrease in appetite and thirst to help the body fight the infection.

What is the purpose of a fever when you're sick?

A fever helps slow down the growth of bacteria and supports the immune system's efforts to destroy pathogens. The rise in body temperature can inhibit bacterial reproduction, aiding in faster recovery.

Why does the body make you sleep when you're sick?

Sleep helps the body conserve energy so it can focus more resources on fighting the infection. It allows the immune system to work more efficiently and helps with the healing process.

How does not eating help in fighting an infection?

When you stop eating, your liver absorbs much of the iron in your blood. Since iron is essential for bacterial survival, this effectively starves the bacteria, helping to weaken the infection.

How does dehydration help reduce the spread of illness?

Mild dehydration reduces the moisture in mucus and other fluids, which can decrease the transmission of viruses through sneezing, coughing, or other bodily fluids. However, severe dehydration can be dangerous and should be avoided.

Why do we feel irritable or sad when we're sick?

Cytokines and prostaglandin can affect neurotransmitters in the brain, such as serotonin and dopamine. This disrupts emotional regulation, leading to irritability, sadness, and sometimes confusion during illness.

Why do autoimmune diseases occur, and how do they differ from typical immune responses?

Autoimmune diseases happen when the immune system mistakenly targets healthy cells in the body, treating them as threats. This differs from normal immune responses, where the body only attacks harmful invaders like viruses and bacteria.

How has the human immune system evolved to protect against illness?

Over millions of years, the immune system has evolved to recognize and defend against a wide range of pathogens. This finely-tuned response helps the body fight infections more efficiently, despite the discomfort caused by symptoms like fever and fatigue.