How do Stimulations Trigger Responses: Stimulus, Sensation, Feeling, and Response

Stimuli, sensation, emotion, feeling, and responses represent a chronological and psychological sequence of how our body reacts to the outer world.

What are Stimuli and How Do They Function

A stimulus is a sensation in the body, whether it originates from the skin, eye, nose, or tongue. We often experience touch sensations, tingling, and prickling, etc.

When a specific nerve or muscle gets agitated, you feel the sensation in a precise spot because your nervous system is wired like a highly organized electrical grid. As a result, your body reacts through multiple channels.

Here is how this localized stimulus works:

Our Body Contains Specific Neural Pathways

• Each patch of skin connects to a unique nerve fiber that travels along specific pathways in the spinal cord.
• These fibers reach a designated area in the brain's sensory map, the somatosensory cortex.
• This map accurately indicates the location on your body where the signal originated, allowing the brain to determine the precise source based on which nerve fiber is active.

Dermatomes of the Human Body's Skin

Our skin is divided into distinct anatomical zones called dermatomes.

Each dermatome is monitored by a unique spinal nerve root.

Pressing or tapping a nerve in your neck can cause tingling in your thumb.

Pinching a nerve root in your lower back can send pain vibrating straight to your big toe.

Trigger Points and Referred Pain

Sometimes, muscles and internal organs can deceive the brain through referred pain caused by nerve convergence.

What is Nerve Convergence?

Multiple nerve fibers from various body parts often converge into the same pathway in the spinal cord. This is known as Nerve Convergence.

When a deep muscle trigger point or an internal organ is irritated, the brain might become confused and interpret the sensation as coming from a different skin area.

The brain might not precisely identify the exact position of the triggering point.

Sensation: the Result of Stimulus or Stimuli

Stimuli send sensations to your brain. So, sensation is the raw physical data. It is the physical input.

Sensory organs such as the skin, eye, ear, and gut send this raw data through the connected nerves to the brain. 

Examples: cold, eye strain, ringing in the ear, or hunger pangs.

The data travels from the nerve endings to the brain. It is entirely neutral before the brain processes it.         

Why is the Gut a Sensory Organ?

The gut is considered a sensory organ because it monitors the food we consume, detecting nutrients, toxins, quantity, pressure, harmful bacteria, and beneficial organisms, and then relays this information to the brain through the nervous system.

Emotion (Body Reactions)

Emotions are the body's physiological responses to raw stimuli received immediately. Emotions are automatic, even though the brain triggers them.

Emotions can be measured by the heart rate, blood flow, and facial expressions.

Feelings

Feelings are the outcome of a conscious awareness of the triggering points and emotions.

These are the outcomes of the conscious mind's thorough interpretation of the data. The mind links physiological experiences to stored brain data. The brain processes this information using our past experiences and acquired knowledge.

While emotion is an automatic limbic response, feeling is the result of conscious mental interpretation and labeling of the data.

Feelings are long-lasting (even for weeks or years), whereas emotions are temporary.

Feelings become linked to your thoughts, past experiences, and memories. They are influenced by your personal history, cultural background, and surroundings.

Response

Response is the outcome of our resulting behaviour.

The stimuli reach the brain, the limbic system triggers emotions and feelings, and we respond to that data in a certain way.

We show anger, get violent, and begin throwing or hitting something. Otherwise, we express joy, excitement, love, and care, and may hug somebody. These are the responses that we show.

Reference;

https://psychology.town/motivation-emotion/emotion-vs-feeling-depth-sensation/

Fingers vs Toes

Your fingers and toes contain bones called phalanges, connected by the joints between them.

Phalanges are the small/long bones that make up our fingers and toes.

We have 14 phalanges in each hand and foot, making a total of 56. 

• The thumb and the big toe have exactly two phalanges. 
• The other fingers and toes have three phalanges each.

So, 3*4 = 12 + 2 = 14. (Twelve in four fingers/toes, plus two in the thumb/big toe)

• The phalanges in the four fingers and toes are known as proximal, middle, and distal (distal being the tip of the finger or toe).
• The phalanges in the thumb or big toe are proximal and distal. They have no middle phalange.

Functional Differences of  Hands (Fingers) and Feet (Toes)

Hands provide you with mobility.

Feet provide stability on the ground.

Hands help you grip, grasp, and handle tasks like writing, typing, stitching, etc.

Feet provide stability, balance, and support when you stand, walk, or run.

Thumb and Big Toe  

Anatomically and structurally, the big toe is the evolutionary equivalent of the thumb.

Both serve as the "first digit" on their respective limbs and share nearly identical bone structures.

Although they share the same genetic blueprint, they evolved differently to serve opposite purposes, as outlined below:

The Thumb serves mobility: 

It has evolved an opposable saddle joint at the base. A saddle joint is one in which one bone is concave-based and the other is convex-based. This allows it to rotate in opposing directions, touch the tips of every other finger, and grip tools.

The Big Toe serves stability: 

It locks in line with the other toes. This provides a rigid lever to bear weight, absorb shock, and push your body forward when walking.

• In alternative therapies like Accupressure and Reflexology, the big toe and the thumb share a functional link. 
• Both points are connected directly to the head, brain, and nervous system. 
• Traditionally, massaging or pressing these digits helps alleviate headaches, lessen mental fatigue, and soothe the mind.

References:

https://en.wikipedia.org/wiki/Hand

https://en.wikipedia.org/wiki/Foot

What is Gravity and How to Measure Gravity?

Gravity is the force exerted by Earth or other planets to pull an object towards their surface.

The acceleration due to gravity on Earth's surface is g = 9.8 meters per each squaresecond.

In physics, g stands for the acceleration due to gravity, and its standard value on Earth is 9.8 m/s². 

This means that when an object is falling freely, its speed increases by 9.8 meters per second (every single second), ignoring air resistance. 

This value forms the foundation for many important concepts in classical mechanics, a branch of physics that studies how objects move and the forces affecting their movement.

Here are some of those fields where the formula for 'g' is used: 

1) Gravitational Field Calculations: 

It is often written as 9.8 m/s² (meters per second squared) or 9.8 N/kg (Newtons per kilogram) when referring to gravitational field strength. 

• Newton is the force needed to accelerate a one-kilogram mass at the rate of one meter per second squared.
• It is expressed as N = 1 kg x 9.8 (m/per Second Squared) = 9.8 Newtons per 1kg of mass. So, the force needed to throw a 1kg mass is 9.8 Newtons.
• The name Newton was chosen to honour Sir Isaac Newton, who established the Three Laws of Motion.

2) Weight Calculation: 

You can calculate the gravitational force (weight) of any object by multiplying its mass by g, using the formula w= mg. 

3) Calculation of Motion in a Vacuum: 

In kinematics, equations for falling objects use g to determine how fast they drop or how high they can travel against Earth's pull.

Approximation of g:

Although the standard value is 9.81 m/s², the commonly used approximation in many physics textbooks and classroom problems is 9.8 m per square second.

Why is Gravity mentioned in Square Seconds?

Gravity is measured in "square seconds" because it describes an acceleration, which is the rate at which speed changes over time.

 

Acceleration measures the change in an object's speed in meters per second over each second.

 

When you write this out as a fraction, it looks like this:

Acceleration = (Change in Speed)\Time = Meters\Second\Second (where change in speed is measured in meters and time in seconds)

In mathematics, dividing a fraction by a variable multiplies the denominators together:

So, it becomes m per second squared.

But in Real Life,

A "square second" does not exist as a physical shape like a square foot of land. 

Instead, it is an abbreviation of "per second, per second."

If you drop a rock from a cliff, Earth's gravity accelerates it at roughly 9.8 m per second each second:

• At 0 seconds: The rock is stationary
• After 1 second: The rock falls at 9.8m/s
• After 2 seconds: The rock falls at the rate of 19.6 meters per second
• After 3 seconds: The rock falls at the speed of 29.4 meters, and so on

The speed increases at the rate of 9.8 m/s for each extra second that passes.

Does it mean that speed increases every second? 

Or does it mean that high-altitude objects fall at greater speeds than low-altitude objects?

It does not mean that gravity is higher at higher altitudes.

It means that speed increases every second while an object falls to the ground.

As long as an object is dropping, gravity continuously adds more speed to it. 

High-altitude objects hit the ground at much higher speeds because they have a longer distance to fall, giving gravity more time (seconds) to accelerate their speed.

• A rock dropped from a 5-meter roof falls for about 1 second and hits the ground at 9.8 m/s
• A rock dropped from a 45-meter cliff falls for about 3 seconds and hits the ground at 29.4 m/s. 

The cliff-rock drops faster at impact because gravity had 2 extra seconds to build up its speed, not because gravity itself was stronger up high.

A Twist in the Story?

In actual physics, Earth's gravity decreases as an object's altitude increases because of the greater distance from the center of the Earth.

• At sea level, g is about 9.81m/per suare second
• At the top of Mount Everest, g drops to about 9.77 meters per second squared.

An object starting at a high altitude actually accelerates a tiny bit slower at first. However, because it has so much time to fall and accumulate speed, it still hits the ground much faster than an object dropped from a lower altitude.

References:

https://byjus.com/physics/value-of-g/

https://www.vedantu.com/jee-main/si-unit-of-acceleration-due-to-gravity-physics-question-answer

https://study.com](https://study.com/academy/lesson/newtons-laws-and-weight-mass-gravity.html

https://www.sciencebuddies.org/stem-activities/speedy-science-how-does-constant-acceleration-affect-distances-traveled

Mass vs Weight

 Mass is the amount of matter in an object, measured in kilograms (kg). It never changes based on your location. 

Weight is the gravitational force acting on that mass, measured in Newtons (N). Weight varies depending on the area's local gravitational force (e.g., you would weigh less on the Moon than on Earth).

Here are some specific differences in how they are defined, measured, and calculated:

The Core Differences Between Mass and Weight

Mass: 

Mass is a fundamental measure of the amount of matter (or material contained) in an object. It is a scalar quantity, meaning it has only size and magnitude, and it remains the same whether you are on Earth, the Moon, or floating in deep space. Additionally, mass measures an object's inertia (its resistance to change in motion), which is its resistance to being moved or accelerated.

Weight: 

Weight refers to the force exerted on a mass by gravity.
Because it is a force (vector quantity), it has both magnitude and direction (pulling downward toward the center of the planet).
Your weight will change if you travel to a location with stronger or weaker gravity, even though your mass never changes. That's why you are lighter on the moon.
Your weight on a mountaintop is lesser as you are farther from the Earth's gravitational force.

The Physics Formula for Gravity and Mass

In physics, weight and mass are linked by Newton's second law of motion (F = ma). 

For gravity, the formula is:

W = mg 

Where:

W is the Weight (in Newtons, N)

M is the Mass (in kilograms, kg)

G is the Acceleration due to Gravity 

On Earth, g is approximately 9.8 m/s². 

Therefore, an object with a mass of 10 kg has a weight of 98 N (10 kg × 9.8 m/s²)

How Do They Measure Mass or Weight

Measuring Mass: 

Use a pan balance or an electronic digital balance.
These tools measure the unknown mass of the object by comparing it to a known standard mass.

Measuring Weight: 

They use a spring balance.
The spring stretches based on the downward pull of the gravitational force acting on the object. 

Example:

Consider a person with a mass of 60 kg:

On Earth, the gravity is strong (9.8 m/s²), so their weight is (60 X 9.8), ie., 588 Newtons (N).

On the Moon, the gravity is only about 1.6 m/s² (roughly one-sixth as strong as Earth). Their mass is still 60 kg, but their weight drops to roughly 98 N from 588 N.

Rice Bag Example:

When you buy a 50 kg bag of rice, the label is actually showing you its mass, not its physical weight in Newtons. So, the weight can change when you travel to a place where the gravitational force is weak.

Even though everyday language uses the word "weight," science and commerce treat it differently.

In real life, Mass is the focus. The manufacturer tells you exactly how much physical rice (matter) is inside the bag.

 

The kilogram (kg) is strictly a unit of mass. If it were a true measurement of weight in physics, it would be labeled in Newtons (N), not in Kgs.

So, in daily life, "to weigh" simply means to put something on a scale.
Because Earth's gravity is relatively constant everywhere we shop, society uses the terms interchangeably.

What the Rice Bag Measures in Physics:

If you want to look at that 50 kg bag of rice through a strict physics lens, the two concepts split:

Its Mass is exactly 50 kg. This stays the same whether you buy the rice in New York, on top of Mount Everest, or on Mars.

Its True Weight is approximately 490 Newtons.
This is calculated by multiplying the mass (50 kg) by Earth's gravity (9.8 m/s²). It will weigh less on a mountaintop or on the Moon.

References:

https://byjus.com/physics/mass-and-weight

https://en.wikipedia.org/wiki/Mass_versus_weight

https://www.vedantu.com/physics/measurement-of-mass-weight