Medulla oblongata controls
- Smelling
- Beating of heart and respiratory movement
- Intelligence and will power
- Balancing of the body
Answer
Beating of heart and respiratory movement
Reason — Medulla oblongata controls breathing, heart function, blood vessel function, digestion, sneezing, and peristalsis of the alimentary canal, etc.
Balance of body is controlled by
- Spinal cord
- Cerebellum
- Cerebrum
- Medulla
Answer
Cerebellum
Reason — Body balance and muscular coordination is controlled by the cerebellum of the brain.
The smell of good food causes watering of your mouth. It is
- Natural reflex
- Acquired reflex
- Inborn reflex
- Ordinary reflex
Answer
Acquired reflex
Reason — Salivation on smelling good food is an acquired reflex that occurs because our brain remembers the taste of the food due to a previous experience.
The structural and functional unit of nervous system is
- Axon
- Nephron
- Neuron
- Dendron
Answer
Neuron
Reason — Neurons are the structural and functional unit of the nervous system.
Name:
(a) The long, extended process of a neuron.
(b) The point of contact between two neurons.
(c) The kind of nerve which carries both sensory and motor neurons.
(d) The nerve which connects the eyes to the brain.
(e) The nerve which connects the nose to the brain.
(f) The nerve which connects the ears to the brain.
(g) Two sub-divisions of the peripheral nervous system.
(h) Two parts of the autonomic nervous system.
Answer
(a) Axon
(b) Synapse
(c) Mixed nerve
(d) The Optic nerve
(e) Olfactory nerve
(f) Auditory nerve
(g) Somatic nervous system and Autonomic nervous system.
(h) Sympathetic and Parasympathetic systems
You are driving your bicycle at a fast speed. Suddenly, a small boy comes in front of your cycle and without wasting any time in thinking, you immediately apply the brakes and the accident is avoided. What name is given to such an action ?
Answer
This is a Conditioned or Acquired Reflex action. This reflex is one which is developed during the lifetime due to experience or learning.
Name the three kinds of neurons
Answer
Three kinds of neurons:
- Sensory Neurons
- Motor Neurons
- Association Neurons
Name the three kinds of nerves
Answer
Three kinds of nerves:
- Sensory Nerves
- Motor Nerves
- Mixed Nerves
Name the three main parts of the brain
Answer
Three main parts of the brain:
- Cerebrum
- Cerebellum
- Medulla Oblongata
Name the two types of reflexes
Answer
Two types of reflexes:
- Natural reflexes
- Conditioned reflexes
Name the two types of effectors
Answer
Two types of effectors:
- Muscle
- Gland
Define Coordination.
Answer
The interlinking of various activities and organs of a living being as per the needs of the body internally or externally is called coordination.
Define Synapse.
Answer
A synapse is a small junction used for communication between two neurons.
Define Impulse.
Answer
A wave of electrical disturbance that runs through the nerves.
Define Reflex action.
Answer
Reflex action is the quick, immediate and automatic involuntary action in the body brought about by a stimulus without the involvement of the brain.
Define Reflex arc.
Answer
The shortest pathway of the nerve impulse from a receptor to the effector which makes a reflex action possible is called a reflex arc.
Write one important role of Cerebrum.
Answer
Intelligence and memory.
Write one important role of Cerebellum.
Answer
Muscular Coordination.
Write one important role of Medulla oblongata.
Answer
Breathing and digestion.
Write one important role of Receptors.
Answer
Receive the stimulus.
Write one important role of Spinal cord.
Answer
Control reflexes below neck.
Write the specific terms/structures for the ‘pathway of a reflex arc’ in a proper logical sequence, starting with stimulus and ending with response/reflex action.
Answer
'Pathway of a reflex arc' is shown below:
Differentiate between the following pairs of terms on the basis of what is indicated within the brackets :
(a) Stimulus and response (definition)
(b) Receptor and effector (examples)
(c) Motor nerve and sensory nerve (function)
(d) Cranial and spinal nerves (number in pairs)
(e) Cerebrum and medulla oblongata (function)
(f) Cerebrum and spinal cord (arrangement of white and grey matter)
Answer
(a) Difference between Stimulus and Response (definition)
| Stimulus | Response |
|---|---|
| Any change in the environment that usually results in change in the activity of the body. | The activity of the body due to the stimulus. |
(b) Difference between Receptor and Effector (examples)
| Receptor | Effector |
|---|---|
| The nerve cells in the skin that receives the stimulus is the receptor. | The muscle of the hand receiving the command from the brain is an effector. |
(c) Difference between Motor nerve and Sensory nerve (function)
| Motor Nerve | Sensory Nerve |
|---|---|
| Motor nerve carries impulses from the brain and spinal cord to the muscles and glands. | Sensory nerve carries impulses from the sense organs to the spinal cord or brain. |
(d) Difference between Cranial and Spinal nerves (number in pairs)
| Cranial Nerves | Spinal Nerves |
|---|---|
| There are 12 pairs of cranial nerves. | There are 31 pairs of spinal nerves. |
(e) Difference between Cerebrum and Medulla oblongata (function)
| Cerebrum | Medulla oblongata |
|---|---|
| The cerebrum is the seat of intelligence, consciousness and will power. It controls all the voluntary activities. | Medulla oblongata controls the activities of the internal organs. |
(f) Difference between Cerebrum and Spinal cord (arrangement of white and grey matter)
| Cerebrum | Spinal cord |
|---|---|
| In Cerebrum, the outer portion contains grey matter and inner portion contains white matter. | In Spinal cord, the inner part contains grey matter and the outer part contains white matter. |
Draw a neat and labeled diagram of a neuron and answer the following questions :
(a) What are the two main parts of a neuron?
(b) Is this structure unicellular or multicellular?
(c) Which part of the neuron contains nucleus?
(d) Name the two parts of the human body where neurons are found abundantly.
(e) How are neurons significant to us?
Answer
Labeled diagram of a neuron is shown below:
(a) Axon and Cyton
(b) Unicellular
(c) Cyton
(d) Brain and Spinal cord
(e) Neurons are significant to us as they are the fundamental building blocks of the nervous system. Neurons carry impulses between sense organs and brain or spinal cord as well as between themselves. They keep us informed about the outside world and bring about control and coordination in our body. They also help in regulating our involuntary activities.
With the help of a suitable example, describe reflex action.
Answer
The peripheral nervous system and spinal cord together control certain actions where the brain is not involved, e.g. when we touch a hot object or get pricked by a pointed object, we instantly remove our hand, without thinking about it. Such an action is called a reflex action.
Briefly differentiate between the following by giving examples:
(a) Voluntary and involuntary action.
(b) Inborn and acquired reflexes.
Answer
(a) Difference between Voluntary and involuntary action
| Voluntary Action | Involuntary Action |
|---|---|
| Voluntary actions occur knowingly. | Involuntary actions occur unknowingly. |
| Cerebrum controls voluntary actions. | Medulla oblongata and Spinal cord controls involuntary actions. |
| Eating apple, watching TV are examples of voluntary actions. | Breathing, beating of heart are examples of involuntary actions. |
(b) Difference between Inborn and acquired reflexes.
| Inborn Reflexes | Acquired Reflexes |
|---|---|
| No previous experience or learning is required for inborn reflexes. | Acquired reflexes develop with experience and learning during the lifetime. |
| Blinking, coughing, sneezing, vomiting are examples of inborn reflexes. | Typing on the keyboard, playing a musical instrument are examples of acquired reflexes. |