Human sensation

📚 Article Contents

  The organism's need for sensation

Learning objectives

Distinguishing between the main functions of the nervous system: sensation, integration, and response.

After examining the components of nerve tissue and the basic anatomy of the nervous system, the next step is understanding how nerve tissues communicate within the nervous system.

A comprehensive study of the nervous system

 Preparation and coordinationExpert researcher Mohamed Abdel Ghani Abdel Hamid, Arabic Biology Blogs – Biomouhagan

 All rights reserved to the researcher. Republishing or reusing the content without express written permission is prohibited. Use of the content for non-commercial educational purposes is permitted with attribution to the source. .

📑 General Index of the Study

1.  Introduction to the nervous system and its vital functions
2.  The anatomical structure of the nervous system (CNS and PNS)
3.  Types of neurons and glial cells and their functions
4. Brain nutrition and neurocirculatory system
5. Electrophysiology and neurochemical transport
6. Common neurological diseases (stroke, Parkinson's, Alzheimer's...)
7. Modern neurodiagnostic techniques
8. Artificial intelligence and neuroregeneration applications
9. Brain structure, lobes, and functions
10. The spinal cord and its neurological and sensory functions
11. Neurotransmitters, synapses, and the role of related drugs
12. Development of the embryonic nervous system
13. Neurodevelopmental disorders in children
14. Neurological drugs and their effect on the brain
15. Lifestyle and its support for nervous system health
16. The relationship between the nervous system and the endocrine glands
17. Perception, memory, and higher brain functions
18. The emotional brain and processing emotions
19. Neuroplasticity and learning from experience
20. The future of neuroscience research and upcoming challenges

Scientific introduction to the nervous system

When we mention the nervous system, we are talking about a biological system that rivals, and even surpasses, the greatest technologies devised by the human mind. The human nervous system is the central communication network, the source of perception, sensation, and thought, and the link that connects us to the outside world..

What distinguishes humans from other living beings is their highly complex nervous system, which allows them to interact precisely with their environment, direct their movements, and shape their thoughts and feelings. This system does not function merely as a collection of connected wires, but as a biological system with internal intelligence, coordinating all conscious and unconscious bodily activities and translating external stimuli into precise internal responses..

This research explores the detailed structure of the nervous system, reveals its vital functions, and examines its mechanisms at the cellular and molecular levels, including neurotransmission, neuroplasticity, and the integration between the brain and peripheral nerves. It also delves into neurological diseases, their diagnosis and treatment, and the future of neuroscience in light of advancements in artificial intelligence and modern biotechnology..

Chemical coordination in the life of a living organism

One of the most important developments in multicellular organisms is the emergence of a means of communication and understanding between these cells. This allows for the coordinated activities and functions of organs and tissues, enabling the organism to achieve its goals of survival and continuity. There are two methods of cell communication in vertebrates:

neural regulation, which relies on the nervous system,

and hormonal regulation, which relies on hormonal secretions from the endocrine glands.

Although hormonal and neural regulation perform the same essential function, there are three key differences in how they carry out this function:

Hormonal regulation is slower in responding to stimuli than neural regulation. Nerve impulses travel very quickly through nerves when stimulated and do not take long to reach neighboring cells. Consequently, the message reaches the affected organ very rapidly. Hormones, on the other hand, secreted in response to a stimulus, travel through the bloodstream to the target organ at a relatively slow speed compared to the speed of nerve impulses.

Hormonal regulation is generally longer-lasting and more sustainable than neural regulation. A stimulus triggers the release of a neurotransmitter, which directly or indirectly elicits a response in the target organ, but the neurotransmitter is quickly broken down, and the response ceases. Hormonally, however, after being transported through the bloodstream to the target organ, the released hormone binds to specific receptors on the cell membrane of that organ, enters the cells, and exerts its effects through a series of activities. This makes hormonal regulation more sustainable than neural regulation. Furthermore,

hormonal regulation has a broader impact than neural regulation. Nerves release neurotransmitters that affect a neighboring nerve or muscle cell, triggering a response in one or more cells within the organ they reach. Hormones, once released, reach the bloodstream, where they are transported to all tissues of the body without exception.

Hormone chemistry: Hormones belong to one of the following hormonal groups:

Amino hormones 

These are amino acid-derived hormones, the smallest hormones in terms of molecular weight. Examples include epinephrine, norepinephrine, and thyroxine. They are water-soluble.

Steroidal hormones

They have a greater molecular weight than amino acids, and examples include male and female sex hormones, all of which are derived from cholesterol (fats), so they are soluble in fats.

Peptide hormones

Larger than the previous two types, these hormones consist of chains of amino acids ranging in number from 3 to 198 and include most known hormones such as TRH and prolactin. They are water-soluble.

Glycoprotein hormones are the largest in size and consist of chains of amino acids linked to sugars. Examples include FSH, LH, and TSH. They are also water-soluble.

Time events necessary for hormones to function

Water-soluble hormones take less time to exert their effects, usually within seconds or minutes, but their effects are short-lived. Steroid hormones, on the other hand, take longer, sometimes days, to become active, but their effects last much longer than those of water-soluble hormones.

Hormone breakdown and inactivation: Most hormones are secreted in an active form, capable of performing their functions immediately after release. However, some hormones are secreted in an inactive or dormant form and are then activated outside the cells that secrete them, such as thyroxine and vitamin D3. When a hormone is released into the bloodstream to exert its required physiological effect, it remains there for a period that can vary in length. Afterward, it is removed from the bloodstream by enzymatic systems located primarily in the liver and kidneys, or in the blood itself. The usable components are reused, while the unusable breakdown products are eliminated by the kidneys through urine or by bile through feces.

Sensation is more pronounced in animals than in plants.

 Because an animal moves from place to place, it is exposed to a large number of stimuli and therefore provides a large number of clear responses, whereas a plant does not move from its position, so the stimuli surrounding it do not change, and therefore it does not respond clearly.

 The human body shivers when exposed to extreme cold.

To provide the body with warmth so that the protoplasm does not freeze.

 Sensation is essential for connection and coordination. 

 The organs work as a harmonious unit, and communication between them is achieved through a network of nerves and nerve centers. The human body consists of several systems (digestive, circulatory, respiratory, excretory, etc.). These systems do not function independently of the other systems; rather, any change in an organ affects the functions of the other organs.

Example: Performing manual work that requires strenuous muscular activity requires more oxygen and nutrients. Therefore, the nervous system alerts the heart to increase its beats, so blood flows to the organ carrying nutrients and oxygen, and it alerts the lungs to increase the rate of breathing (inhalation and exhalation). This is linked to the skin's activity to expel sweat to (get rid of body heat and combustion waste). That is, the systems work as a harmonious unit, and communication between them is achieved through a network of nerves and nerve centers.

How can different bodily functions be controlled?

Control over the various bodily functions occurs as a result of the integration between the nervous system and the endocrine system.

The thing that connects the two systems is the hypothalamus region of the brain.

How does the nervous system differ from the endocrine system?

The nervous system differs from the endocrine system in terms of the speed and duration of its effects:

Sensation works to connect the body of a living organism with the environment in order to adapt to its conditions, and to connect the body's organs with each other in order to coordinate the different types of activity they perform.

1. The nervous system is the group of cells and organs that specialize in receiving stimuli and providing appropriate responses to them. 
2. The nervous system and the endocrine system control all the different bodily functions in humans.
3.  Controlling all activities and rapid reactions such as muscle contraction and coordinating their actions with extreme precision.
4. Receiving internal or external information from the various sense organs, through stimuli via the receptors, and then responding to them by sending nerve impulses (which are electrochemical signals to the various organs of the body).

The goal is:

1. Enabling humans to maintain constant and direct contact with their internal and external environments.

2. Maintaining the balance of the human body's internal environment.

3. The pinnacle of evolution is found in humans because their nervous system is the most highly evolved of all living organisms.

endocrine system 

It is the group of endocrine glands that specialize in carrying out certain responses ordered by the nervous system by secreting hormones {chemical compounds that are released into the blood until they reach the target element and regulate vital processes and reactions such as metabolism and food transformation processes in the body}.

 Synergy Nervous

It is much faster than hormonal synergy because it occurs through the network of nerves that make up the nervous system and are distributed throughout the body, and the command originates from the nervous system itself. Hormonal synergy, on the other hand, occurs through the endocrine glands, which receive their commands from the nervous system (i.e., it requires two systems), unlike the former, which occurs directly through the nervous system.

3) The nervous system maintains the body's balance in cooperation with the endocrine system, thus keeping the internal state of the human body stable and balanced.

4) The autonomic nervous system is connected to involuntary muscles and glands, and therefore it controls involuntary sensations.

5) The nervous system reaches its highest degree of development in vertebrates and its highest degree of sophistication in humans.

6) The nerve cell is the building block of the nervous system.

7) The reflex arc is the building block of nervous activity.

8) The central nervous system includes the brain and spinal cord.

9) The peripheral nervous system includes cranial nerves (12 pairs) and spinal nerves (31 pairs).

The nervous system :  It regulates the neural responses to stimuli that arrive via the body's organs at a very high speed and last for a shorter period, so it adapts and adjusts accordingly.

The hormonal system :  Its effect is slow but lasts for a longer period as the hormones travel from the secreting gland with the blood until they reach the areas of effect.

 What is feeling in humans?

1- Sensation is one of the characteristics of a living organism, and it is more evident in animals than in plants. 

2- Sensation is essential for adaptation because it is influenced by the external and internal conditions of the organism. It is the beginning of a complex process that starts with being alert to a stimulus, then perceiving it, and then responding appropriately in order to achieve adaptation.

3- Sensation is essential for the connection and coordination between the different organs and systems of the body, as each organ senses the condition of the other organ. It is also essential for establishing communication between the body and the environment.

How does the control of different body functions occur? 

This occurs as a result of the integration between the nervous system and the endocrine system. The hypothalamus in the brain connects the two systems.

The nervous system, in cooperation with the endocrine system, maintains the body's balance, thus keeping the internal state of the human body stable and balanced.

 The autonomic nervous system is linked to involuntary muscles and glands, and therefore controls involuntary sensations.

 The nervous system reaches its highest level of development in vertebrates and its highest degree of sophistication in humans.

 the reviewer 

1)      Dr. Abdullah Hassan Khalaf– Lectures in Nervous System Physiology, Faculty of Graduate Studies – Cairo University[

2)      Concepts of Biology – First Canadian Edition, Chapter 16.1– Nerve cells and glial cells

3)      Abstracts of Modern Neuroscience from Peer-Reviewed Journals between 2022–2024

4)      Expert researcher Mohamed Abdel Ghani Abdel Hamid

5)      Biology blogs (Arabic biology) – Biomouhagan

6)      Neuro-artificial intelligence studies and researchBCI published in Nature Neuroscience

7)      Neurotrophic and plasticity data from Harvard Medical Neuroscience Publications

  expert researcherSource : Muhammad Abdulghani Abdulhamid   , Arabic Biology Blogs  – Biomohagan. All rights reserved.