Infographics: Nervous System | Science Class 10 PDF Download

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Human Nervous System
While the spinal cord handles reflex actions, the human brain serves as the body's master 
control center, orchestrating everything from conscious thoughts to involuntary functions. 
This remarkable organ, working alongside the spinal cord as part of the central nervous 
system, processes information from throughout the body and coordinates our responses to 
the world around us.
The Human Brain
Fore-brain
The main thinking region 
that processes sensory 
information from sight, 
hearing, smell, and 
touch. It makes decisions 
and controls voluntary 
muscle movements like 
walking or writing.
Mid-brain
Controls involuntary 
actions that we don't 
consciously think about, 
working with the hind-
brain to manage 
automatic body 
functions.
Hind-brain
Contains the medulla 
(controlling blood 
pressure, breathing, 
digestion) and 
cerebellum (maintaining 
balance and coordinating 
precise movements).
Three Types of Actions
1. Reflex Actions
Automatic responses like 
pupil dilation that happen 
without conscious thought 
through spinal cord 
pathways.
2. Voluntary Actions
Conscious decisions we 
make and control, like 
writing, talking, or moving 
objects around us.
3. Involuntary 
Actions
Automatic body functions 
like heartbeat, breathing, 
and digestion that we 
cannot easily control 
through thinking.
The peripheral nervous system, consisting of cranial nerves from the brain and spinal nerves from the 
spinal cord, facilitates communication between the central nervous system and the rest of the body.
Role of Spinal Cord 
The spinal cord helps the body respond quickly to danger through reflex actions. These are 
automatic, involuntary reactions4like pulling your hand away from something hot4where 
the body acts before the brain even processes the event. This rapid response protects us 
from harm.
The Journey of a Reflex Arc
Receptor
Specialized nerve endings in your skin detect the dangerous heat and convert it into an electrical 
signal.
Sensory Neuron
This nerve carries the "danger" message from your hand toward your spinal cord at incredible speed.
Integration Center
In your spinal cord, the sensory neuron connects directly to a motor neuron, bypassing the brain 
entirely.
Motor Neuron
This nerve carries the "withdraw" command from your spinal cord back to the muscles in your arm.
Effector
Your arm muscles contract instantly, pulling your hand away from the dangerous heat source.
Some Other Examples of Reflex Arc
1. Pupillary Light Reflex
When bright light enters your eyes, your pupils quickly shrink to protect your retinas. This 
happens automatically4the retina senses the light and signals the brain, which then tells the 
iris muscles to constrict the pupils
2. Knee-Jerk Reflex
When a doctor taps below your kneecap, your leg kicks forward automatically. The tap 
stretches tendons, activating receptors that send signals to your spinal cord, which then 
makes your thigh muscles contract. This checks if your reflexes are working properly.