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Important Questions for Class 11 Chapter 21 Neural Control and Coordination are covered in this article. Some of the important topics in Neural Control and Coordination chapter of biology class 11 syllabus include Neural System, Peripheral Nervous System, Forebrain, Hindbrain, Mechanism of vision and Reflex action.
Neural Control and Coordination have an important role in maintaining homeostasis where the functions of the organ system/system in the human body should be coordinated and managed. The interplay of two or more organs that complement each other's functions is called coordination in biology. In the human body, the brain and endocrine systems work together to perform specialised functions.
Given below are some important questions on Control and Coordination for Class 11 students. Conceptual understanding of nerve impulse and action potential will help to understand this chapter better and score higher marks in the upcoming examinations.
Very Short Answers [1 mark]
Ques. How does an impulse travel across a synapse?
Ans. The impulse travels across a synapse from the axons to the cell body and dendrites to the next neuron.
Ques. In the human brain, where does the hunger centre reside?
Ans. The hypothalamus is called hunger centre present near the pituitary gland at the bottom of brain.
Ques. Which of the human eye's three layers are you familiar with?
Ans. The human eye consists of three layers: lens, aqueous humour, and vitreous humour.
Ques. What component of the human eye is photosensitive?
Ans. The retina, which lines the interior of the eye, is mostly made up of light-sensitive cells known as rods and cones.
Ques. What is the distinction between efferent and afferent and neuron?
Ans. Efferent nerve fibres or neurons carry impulses from the Central nervous system (CNS) to the peripheral tissues or organs, whereas afferent nerve fibres carry impulses from the CNS to the peripheral tissues or organs.
Ques. What part of the nervous system is responsible for maintaining balance and coordination of body movements?
Ans. The cerebellum processes all of the information and, in collaboration with the cortex, coordinates muscular action and sends signals to the muscles to modify.
Short Answer [2 marks]
Ques. Make a list of the brain's protective structures.
Ans. The soft and delicate human brain is surrounded by three layers which protect the brain from external shocks and pressure. Thus, the three protective layers of the brain are as follows:
- Cranial Bones: The hard outer covering for the brain is formed by the cranial bones, which are made up of eight bones.
- Meninges: The meninges are three membranes that cover the brain. The pia mater, arachnoid membrane, and dura mater are three layers of tissue that make up the brain.
- Cerebrospinal Fluid: The cerebrospinal fluid or CSF absorbs shocks and is found in the gaps between the meninges.
Ques. What are receptors?
Ans. Peripheral nerve endings in the skin or specific sense organs are called receptors. They become activated after receiving external or internal stimulus and convert it into electrical potential, and ultimately send it to the CNS through afferent neurons.
Ques. Define synapse.
Ans. A synapse is a point where a neuron's axon terminals meet the dendrites or cell bodies of another neuron. At the synaptic junction, a thin fluid-filled area known as the Synaptic Cleft separates axon terminals and dendrites. As a result, the synapse formed by two neurons does not create true continuity between the neurons.
Ques. What biological purposes do the fibres of the dorsal and ventral spinal nerve roots serve?
Ans. Dorsal spinal nerve root fibres carry impulses from peripheral tissues, resulting in sensations like touch, warmth, and pain, as well as involuntary spontaneous activities known as Reflexes.
Ventral spinal nerve root fibres: Some root fibres go directly to skeletal muscle fibres to stimulate or inhibit their activity, while others go to the autonomic ganglia and finish there.
Ques. What does a neuron's action potential mean? Is it true that all neurons have the same action potential?
Ans. Depolarization is induced by a rapid change in membrane permeability, which results in a shift in the ion balance. If the ion shift and subsequent electrical charge shift are adequate, a wave of brief membrane depolarization known as a nerve impulse or Action potential is triggered. Varied neurons have variable concentrations of Na+ ion channels, and their action potentials are different. The action potential of any neuron, on the other hand, is always the same.
Long Answers [3 marks]
Ques. What is the definition of a reflex action? What neural system components are included in a typical vertebrate reflex arc?
Ans. Reflex action is a spontaneous, reflexive, mechanical, nerve-mediated response elicited at the unconscious level by the stimulation of any specific receptor without an organism exercising willpower.
There are around 200 reflexes "wired" into our neurological system, all of which follow the stimulus-to-response sequence along the unique neuronal circuit that makes up the reflex arc. The most basic reflex arc involves a specific receptor, an afferent sensory neuron, sending information to an aggregation of nerve tissue, such as a ganglion or the spinal cord.
Ques. What is the Eustachian tube's function?
Ans. Following are some of the important functions of eustachian tube present in humans:
- It connects the pharynx and the middle ear cavity, allowing pressures on both sections of the eardrum to be equalized.
- The tube has a valve near the pharyngeal opening that is generally closed.
- It opens after swallowing, yawning or a sudden change in altitude when air escapes or enters the tympanic cavity so that the air pressure on both sides of the tympanic membrane is balanced.
Ques. What distinguishes the central and peripheral nervous systems?
Ans. The PNS sends impulses to the CNS, which analyses the information and sends responses to various body locations. The primary differences between CNS and PNS are listed below:
| Central Nervous System (CNS) | Peripheral Nervous System (PNS) |
|---|---|
| The central nervous system consists of the brain and spinal cord (CNS). | The spinal and cranial nerves make up the peripheral nervous system (PNS). |
| No subdivisions in the CNS. | The peripheral nervous system is divided into two parts: the autonomic nervous system and the somatic nervous system, |
Very Long Answers [5 marks]
Ques. How does a depolarization wave travel along with a nerve fibre?
Ans: Nerve cells have polarised membranes, which have a variation in electrical potential across them. The trigger zone of a neuron is the area of the membrane where voltage-gated channels are most densely crowded. When a voltage-gated Na+ ion channel is triggered, a transient, highly localized, but rapid inflow of Na+ ions into the cells occurs, wiping out the local electrical potential difference. This is referred to as depolarization.
When the charge difference between the stimulation site and the membrane surface around it is less, small, localized current forms in the immediate area, causing neighbouring Na+ channels to open and depolarize these cells.
As a result, the depolarization spreads, generating a local current that causes passive Na+ channels to open, depolarizing the near percent site. In this approach, initial depolarization extends outward over the membrane and throughout the nerve fibre, from dendron to axon, in all directions.
Also read: Human Nervous System
Ques. Why is it advantageous for a non-myelinated neuron to carry electrical impulses along a myelinated neuron? What is the name of this sort of conduction?
Ans. In conveying impulses, myelinated nerve fibres are 20 times faster than non-myelinated nerve fibres. This stops impulses from diffusing into nearby fibres. The myelin coating works as a highly insulating barrier, preventing ions from entering the axon from the fluid outside.
In non-myelinated fibres, ionic charges and depolarization are repeated over the membrane and action potentials flow along the entire length of the fibre. Only at the nodes of myelinated axons do ionic changes and depolarization occur again. As a result, the impulse in myelinated fibres is faster and consumes less energy. Saltatory conduction of nerve impulses refers to the hopping of depolarization from node to node.
Ques. Draw a diagram to depict the reflex arc.
Ans. The Reflex Arc is made up of neurons that construct the pathway that nerve impulses take during reflex action.
The reflex arc consists of following:
- Receptor
- From the receptor to the CN system, an afferent neuron or sensory neuron.
- A motor neuron's efferent neuron from the central nervous system to specific muscle fibres or gland cells.
- Afferent to efferent neurons are connected by a series of connectors or intermediate neurons.
When a specific stimulus is delivered to a collection of receptors, the receptor is stimulated, causing a nerve impulse to be initiated along the afferent neurons. The afferent connection and efferent neurons carry this impulse to an effector-muscle or gland for that reflex. As a result, in a reflex arc, the flow of impulse can only be in one direction, i.e.
Stimulus → Receptor → Sensory neuron → Interneuron → Motor neuron → Effector → Response
Ques. Give an account of a man's spinal nerves.
Ans. In a man, there are 31 pairs of spinal nerves. There are two spinal nerves for each section of the spinal cord. Each spinal nerve is a mixed nerve, consisting sensory and motor nerve fibres. It connects the spinal cord to the surrounding tissue. The motor or ventral root and the sensory or dorsal root connect the spinal nerve to the spinal cord.
The Dorsal Root contains sensory or afferent fibres and is surrounded by a dorsal root ganglion. A motor or efferent nerve fibre is found in the Ventral Root. The dorsal root fibres carry impulses from peripheral tissue, resulting in sensations such as touch, warmth, and pain.
The fibres of the ventral nerve root transmit impulses to muscles and glands in the peripheral tissues. The spinal nerve is named after its connection to the vertebral column. These are:
- Cervical Nerves: 8 pairs
- Thoracic Nerves: 12 pairs
- Lumber Nerves: 5 pairs
- Sacral Nerves: 5 pairs
- Coccygeal or caudal Nerves: 1 pair
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