Punjab State Board PSEB 11th Class Biology Important Questions Chapter 21 Neural Control and Coordination Important Questions and Answers.
PSEB 11th Class Biology Important Questions Chapter 21 Neural Control and Coordination
Very Short Answer Type Questions
Which part of the neuron is considered as afferent process?
Dendrites conduct nerve impulses towards the cell body and are called afferent processes (receiving processes).
Give the name of the chemicals, which are released at the synaptic junction. [NCERT Exemplar]
Name the small protein tubular structures between the two neurons.
Which is the largest and most complex of all, the parts of the human brain?
What is the role of afferent nerve fibers in the neural system?
It transmits impulse (sensory) from tissues/organs to the CNS and form, the sensory or afferent pathway.
How does the efferent fibers work?
The efferent nerve fibers transmit motor impulses from CNS to the concerned tissues/organs and form the motor or efferent pathway.
The autonomic neural system is considered as involuntary neural system. Why?
This system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body. So, it is also called involuntary neural system.
How does the somatic neural system works?
The somatic neural system controls the movements of the body by acting on the skeletal muscles (i.e., relays voluntary impulses from the CNS to skeletal muscles).
Give the name of the covering that maintains the shape of the eyeball.
Sclera (outermost layer).
Which is the bluish (pigmented) layer present beneath the sclera?
Which part of our body helps us in maintaining the body balance?
Which of the photoreceptors is responsible for twilight vision?
Short Answer Type Questions
Give a brief description of the neural system.
The neural system is composed of specialized cells called neurons. It detects stimuli and transmits neural signals. The neural system of complex animals is composed of two parts, viz. central neural system and peripheral neural system. The brain and nerve cord comprise the central neural system and other nerves comprise the peripheral neural system.
Explain parasympathetic neural system.
The parasympathetic neural system is part of autonomic neural system. This system has some sort of inhibitory effect. The inhibitory effect minimises the over-functioning of certain functions. Functions, like salivating, digestion, are under control of parasympathetic neural system.
Give a description of the structure of neuron.
A neuron is a microscopic structure composed of three major parts, namely, cell body, dendrites and axon.
Cell Body: The cell body contains cytoplasm with typical cell organelles and certain granular bodies called Nissl’s granules.
Dendrites: Short fibers which branch repeatedly, and project out of the cell body also contain Nissl’s granules and are called dendrites. These fibers transmit impulses towards the cell body.
Axon: The axon is a long fibre, the distal end of which is branched. Each branch terminates as a bulb-like structure called synaptic knob which possess synaptic vesicles containing chemicals called neurotransmitters. The axons transmit nerve impulses away from the cell body to a synapse or to a neuromuscular junction.
Describe reflex action.
The entire process of response to a peripheral neural stimulation, that occurs involuntarily, i.e., without conscious effort or thought and requires the involvement of a part of the central neural system is called a reflex action.
The reflex pathway comprises at least one afferent neuron (receptor) and one efferent (effector or excitor) neuron appropriately arranged in a series.
The afferent neuron receives signals from a sensory organ and transmits the impulse via a dorsal nerve root into the CNS (at the level of spinal cord). The efferent neuron then carries signals from CNS to the effector. The stimulus and response thus forms a reflex arc.
What do you understand by olfactory receptors?
The nose contains mucus-coated receptors which are specialized for receiving the sense of smell and are called olfactory receptors. These are made up of olfactory epithelium which consists of three kinds of cells. The neurons of the olfactory epithelium extend from the outside environment directly into a pair of broad bean-sized organs called olfactory bulb. Olfactory bulbs are extensions of the brain’s limbic system.
Long Answer Type Questions
(a) Give an account of spinal nerves in man.
(b) What biological functions are served by the skeletal system?
(a) There are 31 pairs of spinal nerve in man. From each segment of the spinal cord, there arises two spinal nerves. Each spinal nerve is a mixed nerve, containing both sensory’ and motor nerve fibres. It runs between the spinal cord and peripheral tissue. The two roots, i. e., motor or ventral and sensory or dorsal connect the spinal nerve to the spinal cord.
The DORSAL ROOT carries sensory or afferent fibre and has dorsal root ganglion at its middle. The VENTRAL, ROOT contains motor or efferent nerve fibers. The dorsal root fibres bring impulses from the peripheral tissue and give rise to sensations like touch, temperature, and pain. The ventral nerve root fibres pass impulses to muscles and glands in the peripheral tissues. The spinal nerve has been named according to their relation with the vertebral column.
- Eight pairs of cervical,
- 12 pairs of thoracic,
- 5 pairs of lumbar,
- 5 pairs of sacral and
- a pair of coccygeal or caudal.
- The skeletal system forms the rigid structural framework of the body and supports the weight of the body along with its limbs.
- It affords protection to the internal organs against mechanical injury by forming cage-like compartments, e.g., skull.
- It serves as a storage depot for calcium and phosphate, which are released for a number of functions of the body.
- It participates in movement and locomotion.