Control and Information Processing Chapter Notes | Science for Grade 6 PDF Download

Introduction

This chapter is all about how our body and even plants respond to the world around them. It explains how the nervous system helps us control our actions, balance, and react to things like sound, light, touch, taste, and smell. You'll learn how messages travel through our body, how our senses work, and even how plants respond to things like light and touch. The chapter also talks about a disease called ALS and how it affects the body. By the end, you'll understand how our body and brain work together to help us interact with our environment!

What controls the body's functions?

The nervous system is the part of an organism that gathers, processes, and responds to information. The basic working units of the nervous system are called nerve cells, or neurons.

• Sensory Information and Brain Function:
  • The nervous system receives information through the senses — including vision, hearing, smell, taste, and touch.
  • Sense receptors detect stimuli and send signals through neurons to the brain.
  • The brain acts as the control center of the body. It:
    • Receives and processes information
    • Sends out responses
    • Stores some information as memories
• Parts of the Nervous System: The nervous system has two main parts:
  1. Central Nervous System (CNS):
     • The CNS includes the brain and the spinal cord.
     • It receives, processes, stores, and transfers information.
     • The spinal cord is a tubelike structure made of neurons.
     • These neurons extend throughout the body, helping transmit information to and from the brain.
  2. Peripheral Nervous System (PNS):
     • The PNS includes sensory neurons and motor neurons.
     • These neurons carry information between the CNS and the rest of the body.

A Closer Look: Amyotrophic Lateral Sclerosis

• Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease, is a condition that affects nerve cells in the brain and spinal cord.
• It makes muscles weak and hard to control, and symptoms can include muscle cramps, twitching, weakness, and trouble speaking or swallowing.
• ALS progresses differently for each person and has no cure, but medicine and therapy can help slow it down and ease symptoms.
• About 20,000 people in the United States live with ALS.
• Stephen Hawking, a famous scientist, had ALS and became paralyzed over time but used a computer-based communication system to continue his work.
• He wrote important books like A Brief History of Time and made major contributions to science despite his condition.

How does your body receive information?

• The sensory system is a part of the nervous system that helps detect or sense the environment.
• Humans use their five main senses — vision, hearing, smell, taste, and touch — to understand and respond to their surroundings.
• In addition to the main senses, there are other senses, such as the sense of balance and sense of direction.
• Every part of the sensory system has special structures called receptors. These receptors detect stimuli, and each sense uses different types of receptors to detect specific kinds of information.

How does your body receive information through taste and smell?

• The senses of taste and smell work together using chemoreceptors, which are special receptors that detect chemicals.
• Chemoreceptors in the nose detect odor molecules, and there are hundreds of different receptors for smells.
• Chemoreceptors on the tongue, called taste buds, detect chemicals in food and drinks.
• The nose and mouth chemoreceptors send messages to the brain, which processes the information.
• This can lead to immediate reactions, like spitting out bad food, or create memories, like remembering the smell of rotten milk.

How does your body receive information through touch?

• The skin has millions of nerve endings that detect touch, temperature, pain, and pressure.
• Touch receptors send messages to the brain, which processes the information and can create memories, like remembering the pain of touching something hot.
• The sense of touch helps maintain homeostasis (keeping the body balanced) by detecting harmful stimuli, like heat or cold, so the body can respond.

How does your body receive information through sound?

• Hearing happens when sound waves, created by vibrating matter, travel through air or other substances.
• Sound waves enter the ear and are detected by auditory receptors.
• The waves are amplified in the ear, moving hair cells that send information to the brain.
• The brain processes the loudness and tone of the sound, allowing you to hear.
• The inner ear also helps with balance.

Did You Know? 

The formula for speed is: Speed (m/s) = Distance (m) / Time (s).

How does your body receive information through sight?

• The visual system uses photoreceptors in the eye to detect light (electromagnetic signals) and form vision.
• Light enters the eye through the cornea, a thin membrane that both protects the eye and bends the light rays.
• Iris and Pupil:
  • The colored part of the eye is called the iris.
  • Light passes through the pupil, an opening in the iris.
  • The iris controls how much light enters the eye by changing the size of the pupil:
    • In bright light, the iris contracts, making the pupil smaller to reduce light.
    • In dim light, the iris relaxes, making the pupil larger to let in more light.
• Lens and Retina:
  • After passing through the pupil, light goes through the lens, a clear structure that works with the cornea to focus light.
  • The retina is located at the back of the eye and contains two types of photoreceptor cells:
    • Rod cells
    • Cone cells
  • The retina converts light into electric signals and sends them through the optic nerve to the brain.
  • The brain processes these signals and forms a picture of what you are seeing.

Night Vision Goggle: Would you like to be able to see in the dark?

• Even in the dark, objects give off or reflect infrared light, which humans cannot see.
• Night vision goggles collect infrared light and convert it to visible light.
• Infrared light enters the goggles’ objective lens, is turned into electrons, and sped up in an image intensifier tube.
• The electrons hit a phosphor screen, which converts them back into photons, creating a visible image.
• Owls see better in dim light than humans because they have more rod cells in their retinas, which are sensitive to low light.

How do plants respond to stimuli?

• Plants respond to stimuli, but their responses are often very slow, making them difficult to observe.
• Some responses can take hours or even days to become noticeable.
• Response to Light:
  • Light is a type of stimulus.
  • A plant responds to light by growing toward the light source.
  • This growth happens gradually over several hours.
• Response to Touch:
  • Some plant responses are quick, such as in the Venus flytrap.
  • When an insect touches the trap, it snaps shut immediately, trapping the insect.
• Response to Gravity: Plants also respond to gravity by adjusting their growth direction — for example, roots grow downward and stems grow upward.