Nervous System Flashcards
State three uses of nervous system
- Enables us to remember and think
- Informs us about our surroundings
- Regulates involuntary activities
What are the three main parts of neuron?
- Cell body (peri karyon or cyton)
- Dendrites
- Axon
State two characteristics of Cell body
- It has well-defined nucleus
- Lost centrosome
State two characteristics of Axon
- It has gaps throughout length called nodes of ranvier
- It is covered by insulating sheath called Myelin or medullary sheath. This sheath is covered by an even thinner sheath known as Neurolemma
Define Stimulus
A sudden change in external and internal environment that evokes a response in an organism.
Define receptors
These are parts of NS that gather environmental signals or perceive the stimuli and pass them to CNS for interpretation.
Define effectors
Muscles or glands which on receiving the impulse from the brain or spinal cord, contract or secrete substances
Conduction of nerve impulse is a wave of _____ followed by ______
- Depolarization
- Repolarization
Define synapse
It is the point of contact between the axon of a neuron and the dendrite of another neuron
What are the three types of neurons?
- Sensory neurons - receptor to CNS
- Motor neuron - CNS to effector
- Association (connecting) neurons - interconnect Motor and sensory
Define nerves
Nerve is a bundle of nerve fibers (axons) of secrete neurons, enclosed in a tubular sheath
State the three kinds of nerves:
- Sensory nerves - optic nerve
- Motor nerve - nerve from brain to eye
- Mixed nerve - spinal nerve
Define ganglia
Ganglia are the aggregates of the futons or cell boxes of nerve cells from which the nerve fibers may arise or enter into.
What are the two major divisions of Nervous system?
- Central Nervous system - brain and spinal cord (contained within vertebral column)
- Peripheral nervous system - includes nerves that emerge from and enter into Brian and spinal cord.
Name the two subdivisions of PNS
- Somatic nervous system - conveys info to skeletal (voluntary) muscles
- Autonomic nervous system - involuntary actions (heart muscles, glands)
What is the brain protected by?
Brain box or cranium
Name the meninges of the brain
- Outermost - Dura Mater
- Middle - Arachanoid
- Innermost- Pia Mater
What is meningitis
Meningitis is the inflammation of the meninges
State the function of cerebrospinal fluid
Protects the brain and spinal cord from mechanical shocks
Name the 3 parts of the brain and state functions of each.
- Cerebrum : consciousness, voluntary actions
- Cerebellum : balance of body, coordination of muscular activity.
- Medulla oblongata : controls activities of internal organs , peristaltic movements, breathing, beating of heart
What is outer (cortex) of Brian called
Gray matter
What is inner layer of brain called?
White matter
What connects the two cerebral hemispheres in the cerebrum?
Corpus Callosum (hard body)
What are the fold and grooves in cerebrum called?
- Folds - gyri
- Grooves - sulci
What cerebellum also called?
Little brain
What are the three primary regions of brain?
- Forebrain - a) cerebrum
b) diencephalon - Midbrain
- Hindbrain - a) cerebellum
b) pons
c) medulla oblongata
What layer lies inside and outside of the spinal cord? State two functions of spinal cord:
- Inside - gray matter
- Outside - white matter
Two functions -
a) reflexes below the neck
b) conducts sensory and motor responses
Name the two divisions of the Peripheral Nervous System
- Somatic
A) cranial nerves - 12 pairs
B) spinal nerves - 31 pairs - Autonomic
A) sympathetic
B) parasympathetic
Which hormone stimulates the SNS?
Adrenaline secreted by Adrenal Glands
What is the function of sympathetic system and parasympathetic system?
Sympathetic - prepares body for violent action against abnormal conditions
Parasympathetic - concerned with re-establishing normal conditions after violent act is over
Define Reflex Action
It is an automatic/quick/immediate involuntary action in the body brought about by a stimulus.
What are the two types of reflexes and give two examples of each.
- Inborn or natural reflexes
No prior experience is required
E.g. blinking, coughing, salivation, peristalsis - Conditioned or acquired reflexes
Involuntary spontaneous automatic response brought about due to previously learned experience.
E.g. salivation at seeing familiar food
What is a reflex arc?
A reflex arc is the shortest route that can be taken by an impulse from a receptor to an effector.
State the reflex arc in humans:
Stimulate —> receptor —> sensory neuron —> brain or spinal cord —> motor neuron —> effector —> response
