Nervous System Flashcards
What is Coordination?
Coordination is interlinking of various activities like digestion respiration excretion etcetera going on in the body as per the needs internally or externally.
How is chemical coordination brought about?
Chemical coordination is brought about the chemical messengers called hormones produced by endocrine glands.
What are the functions of the nervous system?
1.It keeps us informed about the outside world.
2. It enables us to think remember and reason out
3. It controls in harmonizes all voluntary muscular activities.
4. It regulates involuntary activities such as beating of heart breathing etc.
Name the structural and functional unit of the nervous system
Neuron
What are the main parts of the neuron
- Cyton / cell body / perikaryon
- Dendron and dendrites
- Axon
- Axon Terminals
Why have nerve cells lost the ability to divide?
Centrosome is absent in the cell body hence the nerve cells have lost ability to divide.
What are association neurons
Association neurons are located in the brain and spinal cord which interconnect the sensory and motor neurons of the body and conduct nerve impulses to the cyton.
What is an Axon
It is a long process from the cell body in most neurons it is surrounded by a white insulating sheet called mylin sheet and shows a gap through the length called node of ranvier.
Axon terminals are place near the dendrite of another neuron but are not connected.
Define synapse
The point of contact between the terminal endings of the neuron with the dendrites of another neuron separated by a fine gap is called synapse.
What is the direction of impulse in sensory neurons.
Sensory neurons carry impulse from a receptor sense organs to the CNS to he brain or spinal cord.
What is the direction of impulse in motor neurons.
They carry impulse from the CNS to the effector organ.
Define a nerve
Formed of a bundle of axons enclosed in a tubular medullary sheath.
What are the three types of nerves and what type of the fibres do they contain?
- Sensory nerve: contains only sensory nerve fibres. 2. Motor nerve: contains only motor nerve fibres.
- Mixed nerve: carries both sensory and motor nerve fibres
What are the parts of the brain
- Cerebellum
- Medulla oblongata
- Cerebrum
Write a short note on cerebrum
– It is the largest portion of the brain.
– It is divided into two cerebral cerebral hemispheres. – Outer surface is highly converted with ridges and grooves called gyri and sulci.
– Each hemisphere is internally hollow though the middle and the walls have two regions - outer cortex containing cyton of the neuron grayish in color called gray matter, and Inner medulla containing axon= white matter.
What is function of the cerebrum
It is seat of intelligence centre of consciousness will power and controls all voluntary actions.
Why the outer surface of brain highly convolulted?
To increase surface area to accommodate more neurons.
Location of the cerebellum
It is a smaller area of brain located at the base and under the cerebrum.
State function of the cerebellum
It coordinates the muscular activity and balance of the body.
Give reason why alcoholic person when drunk walk clumsily
Alcohol affects cerebellum which coordinates the muscular activities and maintains the balance of the body. As the balance of the body is lost the person walks clumsily.
Location of medulla oblongata
It is the lowest portion of the brain located at the base of the skull.
It is continued behind the spinal cord.
What is the function of the medulla oblongata
It controls all involuntary activities such as breathing, heartbeat etc.
Why does injury to the medulla oblongata results in death.
Medula oblongata controls involuntary actions hence when medulla oblongata is injured the movements like breathing and beating of heart stops and the person dies.
What is the location of the spinal cord
Extends from the medulla oblongata to the end of the second lumbar vertebrae and lies within the neural canal of the vertebrae.
How is the arrangement of the neurons in the spinal cord
Outer portion is white matter made up of axon and inner portion is grey matter made up of cyton.
Functions of the spinal cord
- Conducts reflexes below the neck.
- Conduct sensory impulses from the skin and the muscles to the brain.
- Conducts motor responses from the brain to the muscles of the trunk and the limbs.
What is the function of the peripheral nervous system
It consists of nerves which connect the central nervous system to all parts of the body.
What is the difference between the cranial and spinal nerves of the somatic nervous system.
The cranial nerves emerge from the brain
they are 12 pairs of cranial nerves
hey can be sensory nerves motor nerves or mixed nerves
Spinal nerves emerge from the spinal cord there are 31 pairs of spinal nerves and every spinal nerve is a mixed nerve.
What is the difference between the sympathetic and the parasympathetic nervous system parts of the autonomic nervous system
Sympathetic is stimulated by hormone adrenaline and prepare the body for emergency actions.
Parasympathetic nervous system is brought back to normal conditions by hormone nor-adrenaline and re-establises normal conditions.
What is stimulus
Any change in the environment that can cause a response or reaction in the body.
Response
Response is changed an organism resulting due to stimulus.
What is an impulse
It is a wave of electrical disturbance that runs through the nerves.
What are receptors
Highly specialised sensory cells on neurons that are sensitive to a specific stimulus.
What are effectors
Muscle or gland that responds to motor nerve impulse.
What is a reflex arc
It is a shortest route that can be taken by an impulse from a receptor to an effector.
What is reflex action
It is a sudden, spontaneous and involuntary action in the body brought about by a stimulus.
What are the two types of reflexes
Natural or simple reflex which is inborn and conditioned reflex which is acquired.
Natural reflex short note
–No previous experience is required
–directly related to the stimulus
–similar in all humans
Conditioned reflex short note
– Develops due to experience or learning
– unrelated to stimulus
– differs in different individuals.
