The Nervous System Flashcards
Why do we need nervous system ?
1] Keeps us informed about the outside world
2] Enables us to think ,to remember ,to reason out
3] Controls and harmonises all the voluntary muscular activities
4] Regulates involuntary activities
Mention features of a Axon.
1] It is a long process from cell body.
2] It is covered by a white insulating sheath called myelin sheath
3] myelin sheath was covered by a thin sheath called neurolemma
4] myelin sheath shows gaps throughout the length called Nodes of Ranvier.
Define stimulus
An agent or a sudden change of the external or internal environment that results in a change in an organism or any of its body parts.
Define Response
The change in an organism resulting due to stimulus.
Define Impulse
A wave of irritability (electrical disturbance)
Define Receptors
The specialised epithelial cells which on receiving the stimulus ,set up waves of impulses towards the central nervous system.
Define Effectors
Muscles or glands which on receiving the impulse from the brain or spinal cord, contract or secrete substances
Define Synapse
Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap
What are types of neuron?
1] SENSORY NEURONS convey the impulse from the receptors to main nervous system
2] MOTOR NEURONS carry the impulse from main nervous system to an effector.
3] ASSOCIATION NEURONS are located in the brain and spinal cord , which interconnect the sensory and motor neurons.
Define Nerve. What are types of nerves ?
Nerve is a bundle of nerve fibres of separate neurons , enclosed in a tubular sheath.
Types of nerves :
1] SENSORY nerves contain only sensory fibres.
2] MOTOR nerves contain only motor fibres.
3] MIXED nerves are those who contain both sensory and motor fibres
What are division of nervous system and what do they consist of?
The 2 major divisions of nervous system are
Central nervous system and Peripheral nervous system.
Central nervous system consists of the brain and spinal cord.
Peripheral Nervous system is further divided in Somatic and Autonomic Nervous system.
Somatic nervous system consists of cranial nerves, spinal nervous. Autonomic nervous system is further divided into Sympathetic and Parasympathetic system
Write a brief note on the Human Brain.
- In proportion, to the size to the size of body human brain is the largest among all the animals
- The brain is covered by 3 membranous coverings called MENINGES
- The inflammation of meninges is called Meningitis
- Dura meter is the outermost layer, Arachnoid is the thin middle layer, Pia meter is the innermost layer with very rich supply of blood.
- It has 3 parts called CEREBRUM, CEREBELUM , MEDULLA OBLONGATA.
What are 3 regions brain is divided in? What are the parts in these regions and mention there functions ?
1] FOREBRAIN
Cerebrum - seat of intelligence , consciousness, will power, etc.
Diencephalon - Thalamus(relays pain and pressure impulses to cerebrum).Hypothalamus(controls the body temperature and pituitary)
2] MIDBRAIN
A small tubular part - reflexes involving eyes and ears
3] HINDBRAIN
Cerebellum - coordinates muscular activity, balance of the body.
Pons - located in the center of the brain below cerebellum to the other hemisphere and coordinates muscle movements.
Medulla Oblongata - controls internal organs, heartbeat breathing, etc.
How many cranial and spinal nerves do we have ?
- There are 12 pairs of cranial nerves
- There are 31 pairs of spinal nerves
8 nerves in the neck region
12 pairs in thorax
5 pairs in lumbar region
5 pairs in sacral
1 pair in coccygeal parts
What are functions of Sympathetic and Parasympathetic nervous system.
- Sympathetic nervous system accelerates heart beat, dilates pupil, constricts blood vessels, etc.
- Parasympathetic nervous system restores normal body condition.
