Physical Basis of Mental Life: NBSE Class 12 Education
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Summary
Our minds and bodies are closely linked. What happens to our body can affect our thoughts, and our thoughts can affect our body. This connection is managed by the nervous system, which acts like the body’s main communication network. It has two main divisions. The Central Nervous System, or CNS, is made up of the brain and the spinal cord. It is the body’s main control center. The Peripheral Nervous System, or PNS, consists of all the nerves that branch out from the CNS to the rest of the body, connecting it to the outside world.
The brain is the most complex part of the nervous system. It is protected by the skull and has several important regions. The cerebrum is the largest part and is responsible for thinking, memory, and voluntary actions. The cerebellum, located at the back, controls balance and coordinates our movements. The brain stem connects the brain to the spinal cord and manages vital automatic functions like breathing and heartbeat. The brain works by sending and receiving signals to control everything we do.
The nervous system is made of billions of special cells called neurons. A neuron receives signals through branches called dendrites and sends signals out through a long fiber called an axon. The small gap where a signal passes from one neuron to another is called a synapse. Sometimes the body needs to react very quickly without thinking, like when you touch something hot. This is a reflex. The signal for a reflex travels along a simple path called a reflex arc, from a sense organ to the spinal cord and then directly to a muscle.
We learn about the world through our senses. The process of our sense organs, like our eyes and ears, gathering basic information is called sensation. Sensation is like receiving raw data. For example, your eyes detect light and color, and your ears detect sound waves. After sensation comes perception, which is how our brain organizes and interprets this data to give it meaning. Perception turns the raw data of light and color into the image of a friend’s face.
Our past experiences and expectations can change how we perceive things. Sometimes, our brain can misinterpret information, which is called an illusion. For example, a rope in a dark room might be perceived as a snake. Beyond perception, we form concepts. A concept is a general idea that helps us group things together, like the concept of “dog” which includes all different breeds. Sensation, perception, and conception work together to help us understand and interact with our environment.
Textual
Very Short Answer Questions
1. Expand the terms CNS and PNS.
Answer: CNS stands for the central nervous system and PNS stands for the peripheral nervous system.
2. Name the specific subdivisions of the autonomic nervous system concerned with the following:
(a) Slowing down the heart beat
(b) Increasing salivary secretion
(c) Dilatation of the pupil
(d) Increasing intestinal peristalsis
(e) Muscle contraction of the urinary bladder giving of the feeling the need for urination.
Answer: The specific subdivisions of the autonomic nervous system are:
(a) The parasympathetic nervous system is concerned with slowing down the heart beat.
(b) The parasympathetic nervous system is concerned with increasing salivary secretion.
(c) The sympathetic nervous system is concerned with the dilatation of the pupil.
(d) The parasympathetic nervous system is concerned with increasing intestinal peristalsis.
(e) The parasympathetic nervous system is concerned with the muscle contraction of the urinary bladder, which gives the feeling of the need for urination.
3. Name the two divisions of the nervous system.
Answer: The two major divisions of the nervous system are the central nervous system (CNS) and the peripheral nervous system (PNS).
4. Name the chemical involved in the transmission of nerve impulse across a synapse.
Answer: The chemical involved in the transmission of nerve impulse across a synapse is acetylcholine.
5. State the functions of the following parts of the eye:
(a) Iris
(b) Ciliary muscles
(c) Pupil
(d) Vitreous humour
(e) Retina
Answer: The functions of the parts of the eye are:
(a) The iris is the colored part of the eye, responsible for controlling the size of the pupil and, therefore, regulating the amount of light entering the eye.
(b) These muscles are attached to the lens and change its shape, allowing the eye to focus on objects at different distances. When the ciliary muscles contract, the lens becomes thicker, decreasing its focal length for focusing on near objects. When the muscles relax, the lens becomes thinner, increasing its focal length for viewing distant objects.
(c) The pupil is the black opening in the center of the iris through which light enters the eye. Its size is controlled by the iris muscles to regulate the amount of light reaching the retina.
(d) The vitreous humour is involved in the transmission of light, as reflected light rays from an object enter the eyes through it.
(e) The retina is the innermost sensitive layer where an image is formed. It contains two kinds of sensory cells: the rods, which are sensitive to dim light, and the cones, which are sensitive to bright light and colours.
6. Name the following:
(a) Area of sharp vision in the eye
(b) The kind of lens used for correcting near-sightedness
(c) The condition in which the lens of the eye turns opaque
(d) The capacity of the eye to focus objects at different distances
Answer: The names are as follows:
(a) Area of sharp vision in the eye: The Fovea (also called Fovea Centralis).
(b) The kind of lens used for correcting near-sightedness: Concave lens.
(c) The condition in which the lens of the eye turns opaque: Cataract.
(d) The capacity of the eye to focus objects at different distances: Accommodation (or Power of Accommodation).
7. Name the following:
(a) The part into which the sound waves are directed by the ear pinna.
(b) The kind of balance with which the semi-circular canals are concerned.
(c) Any two sensations felt through free nerve endings in the skin.
Answer: The names are as follows:
(a) The ear pinna directs sound waves into the auditory canal.
(b) The semi-circular canals are concerned with the physical balance of the body.
(c) Two sensations felt through the skin are pain and heat.
Short Answer Questions
1. Give brief details of the nervous system.
Answer: The nervous system has three main functions: sensory input, integration of data, and motor output. Sensory input is when the body gathers information or data through neurons, glia, and synapses. The nervous system is composed of excitable nerve cells called neurons and synapses that connect them to centres throughout the body. It consists of about 100 billion neurons, which are its simplest parts, and the neuron is the structural unit of the nervous system. The nervous system is comprised of two major parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
2. Give a brief classification of the nervous system.
Answer: The nervous system is comprised of two major parts or subdivisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
The Central Nervous System (CNS) includes the brain and the spinal cord.
The Peripheral Nervous System (PNS) consists of all nerves arising from the brain and the spinal cord. It includes nerves and ganglion. The PNS consists of two kinds of pathways: the afferent (receiving) sensory pathways and the efferent (carrying away) motor pathways. The efferent pathway is subdivided into the somatic nervous system and the autonomic nervous system. The autonomic nervous system consists of two parts: the sympathetic nervous system and the parasympathetic nervous system.
3. Name the main parts of the brain.
Answer: The brain consists of three main regions:
- Forebrain consisting of cerebrum and diencephalon,
- Midbrain, a small tubular part between the fore and the hindbrain, and
- Hindbrain consists of cerebellum, pons, and medulla oblongata.
4. What are the two subdivisions of the autonomic nervous system?
Answer: The autonomic nervous system consists of two parts: (a) Sympathetic nervous system and (b) Parasympathetic nervous system.
5. What is gray matter?
Answer: The outer region of the cerebral hemispheres, called the cerebral cortex, contains cell bodies of the nerve cells and because it is grayish in colour it is called gray matter.
6. Mention the one function each of (a) Cerebrum (b) Cerebellum (c) Medulla oblongata (d) Hypothalamus
Answer:
(a) Cerebrum: It carries out mental activities of thinking, reasoning, planning, and memorising.
(b) Cerebellum: It helps to maintain the balance of the body.
(c) Medulla oblongata: It is the centre for breathing, coughing, and swallowing.
(d) Hypothalamus: It controls motivated behaviour such as eating, drinking, and sex.
7. Give two examples of sensory nerves.
Answer: Two examples of sensory nerves are the optic nerve, which is stimulated by photon waves, and the auditory nerve, which carries impulses from the ear to the brain.
8. Name the respective areas of the retina concerned with best vision and no vision.
Answer: The area of the retina concerned with the best vision is the yellow spot. The area concerned with no vision is the blind spot, as there are no sensory cells at this point.
9. State the alternative terms for sensory and motor nerves.
Answer: The alternative term for sensory nerves is afferent, and the alternative term for motor nerves is efferent.
10. What is the role of the eustachian tube in the ear?
Answer: The Eustachian tube connects the tympanic cavity with the pharynx. Its role is to equalise the pressure on both sides of the eardrum or tympanum.
11. List the functions of medulla oblongata.
Answer: The functions of the medulla oblongata are:
- It is the centre for breathing, coughing, swallowing, etc.
- It controls heartbeat, the movement of the alimentary canal, and many other involuntary actions.
Long Answer Questions
1. Name and explain the event that happens immediately when a nerve fibre gets stimulated.
Answer: When a neuron is stimulated, a nervous impulse of an electrical character is produced. This event is the immediate result of stimulation. A nerve impulse is an energy change within the neuron itself.
Stimulation is defined as a “change in the environment of nervous tissue which is sufficient to excite it.” This does not mean that energy is transmitted into the nerve cell from the outside. Instead, the energy change is contained within the neuron and is released by the dendrites. This impulse is then transmitted by way of the axon. The nature of this nervous impulse is partly electrical, partly chemical, and partly thermal. It is also called a nerve current because electrochemical waves are produced during nervous action.
2. Differentiate between sympathetic and parasympathetic nervous systems.
Answer: The sympathetic and parasympathetic nervous systems are the two subdivisions of the autonomic nervous system. The main difference between them is their function in the body. The sympathetic nervous system prepares the body for facing emergency situations. In contrast, the parasympathetic nervous system reestablishes the normal conditions once the emergency is over.
The opposite effects of these two systems on different organs are listed in the table below:
| Organ | Effect of Sympathetic Activity | Effect of Parasympathetic Activity |
| 1. Eye pupil | Dilated | Constricted |
| 2. Heart beat | Speeded up | Slowed down |
| 3. Blood vessels | ||
| a. on skin | Constricted | Dilated |
| b. on muscles | Dilated | No effect |
| 4. Bronchioles | Dilated | Constricted |
| 5. Urinary bladder | Muscles relaxed | Muscles contract (feeling of urination) |
| 6. Sweat secretion | Sphincter contracted | Sphincter relaxed |
| 7. Blood sugar | Increased | No effect |
| 8. Salivary secretion | Stops | Increased |
| 9. Tear glands | Activated | Slowed down |
| 10. Erector muscles of skin hair | Stimulated (hair raised) | Relaxed (hair flattened) |
| 11. Adrenal glands | Increased secretion of adrenalin | No effect |
| 12. Intestine | Peristalsis decreased | Peristalsis increased |
| 13. Stomach glands | Decreased secretion | Increased secretion |
3. Explain the following terms: (a) Synapse (b) Stimulus (c) Impulse
Answer:
(a) Synapse: A synapse is the form of connection between neurons, which is by contact only. It is not a physical object like a neuron but is the point of junction between the axon of one neuron and the dendron of the next neuron in the conduction path of a nerve impulse. The function of a synapse is to resist the nervous impulse as it is conducted from one neuron to another.
(b) Stimulus: A stimulus is a “change in the environment of nervous tissue which is sufficient to excite it.” For example, the eye reacts to light, and the skin to temperature changes.
(c) Impulse: A nervous impulse is an energy change of an electrical character that is produced when a neuron is stimulated. This impulse is contained within the neuron and is released by the dendrites and transmitted by the axon. The nature of the nervous impulse is partly electrical, partly chemical, and partly thermal, and it is also called a nerve current because electrochemical waves are produced in the process of nervous action.
4. Nervous system is the basis for mental life. Justify.
Answer: The nervous system is the basis for mental life because there is a close relation between the mind and the body.
This connection is evident in several ways. For instance, an injury to or disease of a part of the brain can produce a mental disorder or loss of consciousness. The influence of bodily conditions on mental processes is also a matter of common observation; for example, drinking strong coffee causes mental stimulation, and sleeping drugs have a sedative influence.
Conversely, mental processes can influence bodily conditions. Under hypnotic suggestion, a strong pinprick may not hurt at all. The advancement of behaviour in animals is connected with the development of their nervous system, and the evolution of the brain corresponds to the evolution of intelligence. Furthermore, emotional life is closely connected with parts of the nervous system like the thalamus, sympathetic, and parasympathetic systems.
5. Differentiate among perception, sensation and conception in cognitive development.
Answer: Sensation, perception, and conception are distinct but related processes that play an important role in cognitive development.
Sensation is the process by which our senses gather information from the environment and send it to the brain. It is the initial step that allows a child to gather information through seeing, hearing, tasting, and smelling. Sensation is a normal, initial mental process that begins with a stimulus and is based on external conditions.
Perception refers to the interpretation of what we take in through our senses. It is the way we make sense of the raw information provided by sensation. For example, perception allows a child to take in sensory information and convert it into a signal that the brain can understand and act upon. Perception is a complex and refined mental activity that is linked with actual life experience and is influenced by internal mental conditions and past experiences.
Conception involves making meaning out of all the incoming information from sensation and perception. Concepts are mental categories used to group objects, events, and information. Conception organises the interpreted information into these categories for better understanding and comprehension, reducing our experience of the world down to the fundamentals.
6. Draw a neat labelled diagram of neuron and mention its function.
Answer: A neuron is a nerve cell and the structural unit of the nervous system. Its function is to receive and transmit nerve impulses.
A neuron has two types of branches: a single axon and a number of dendrites. The function of the dendron (or dendrite) is to receive the nerve impulse and transmit it to the cell body. The function of the axon is to conduct the nerve impulse away from the cell body to a muscle or gland.
From a functional point of view, neurons can be of two kinds: sensory (or afferent) and motor (or efferent). Sensory neurons carry impulses from a sense organ to the central nervous system, while motor neurons carry impulses from the central nervous system to muscles or glands. There are also connective neurons, which connect the afferent and efferent neurons.
Additional
Extra Questions and Answers
1. What is the theory of psychophysical parallelism?
Answer: The theory of psychophysical parallelism states that mind and body, being two entirely different entities in nature, move in parallel lines. Parallelism in its extreme form asserts a strict point-to-point correspondence between mental processes and a certain group of physical processes, but denies interaction between the two series.
89. Discuss the mind-body problem. Elaborate on the theories of psychophysical parallelism and interactionism.
Answer: The final relation between mind and body is a metaphysical problem because it is difficult to understand how mind and body, being two entirely different entities in nature, could act and interact upon one another. The solution to this problem is beyond the scope of psychology. There are different theories regarding this relation, primarily psychophysical parallelism and interactionism.
Psychophysical parallelism was proposed by the philosopher Spinoza. This theory suggests that mind and body, both being expressions of God, the ultimate reality, move in parallel lines. In its extreme form, parallelism asserts a strict point-to-point correspondence between mental processes and a certain group of physical processes but denies any interaction between the two series.
- Difficulties with Parallelism: While there is a certain parallelism between physical and mental change, the doctrine of strict point-to-point correspondence is not borne out by empirical evidence. Furthermore, it leaves the connection of body and mind wholly mysterious.
Interactionism is the alternative theory. The doctrine of interaction couples the assertion of causal interaction with the denial of parallelism. Interactionists contend that either certain mental occurrences have no bodily correlative or that certain characteristic features in conscious life have no parallel in the bodily process.
- Difficulties with Interactionism: The doctrine of interaction is not without its difficulties. If interaction occurs, it is of an entirely different kind from the interaction of physical things. Ultimately, the connection is as mysterious as it is on the alternative theory of parallelism.
Neither parallelism nor interactionism, in the forms in which they have generally been expressed, provides a satisfactory account of the relations between physical and psychical facts. The problem is largely extra-psychological, and its solution depends in part on metaphysical questions regarding the nature of causation and the ultimate nature of matter and mind.
Extra MCQs: Knowledge-Based
1. What is the largest part of the human brain, responsible for intelligence?
A. Cerebellum
B. Medulla oblongata
C. Cerebrum
D. Diencephalon
Answer: C. Cerebrum
31. The __________ is the part of the eye where the optic nerve connects, and it has no sensory cells.
A. yellow spot
B. retina
C. pupil
D. blind spot
Answer: D. blind spot
Extra MCQs: Competency-Based
32. Cerebrum: Intelligence :: Cerebellum: __________
A. Emotion
B. Balance
C. Breathing
D. Memory
Answer: B. Balance
46. (I) The medulla oblongata controls involuntary actions.
(II) Breathing and heartbeat are regulated without conscious thought.
A. I is a contradiction of II.
B. I and II are unrelated.
C. II is an example of the principle stated in I.
D. I is the result of II.
Answer: C. II is an example of the principle stated in I.
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