The nervous system Flashcards
What is a stimulus and a response
A change in environement that is detected by your body
response is your bodies reaction to that stimulus
What is a nerve cell?
a neuron
What is a bundle of neurons called?
a nerve
define a neuron ? (2)
a cell that uses electrical signals (impulses) to communicate with other cells in the body
- the impulse moves through the body at very fast rate, allowing for quick response
Name the parts of the neuron
what is a synapse?
large cell body (contains nucleus)
short dendrites (carry signals from outside the neuron
towards the cell body)
a single long axon (carries impulse away from cell body and
towards other cells)
some axons are covered with a myelin sheath which allows
the impulses to travel even faster.
terminal knobs at the ends of the axon attach the neuron to other neurons
or muscle cells and allows the impulse to reach its target.
the connection between the terminal knob of a neuron’s axon and a
dendrite of an adjacent neuron or muscle cell is called a synapse
Types of neurons
1) Sensory neurons carry impulses from receptors in the eyes
(sight), ears (hearing), tongue (taste), skin
(heat and pressure) to the brain.
- Interneurons neurons in the brain or spinal cord that link the
sensory neurons and the motor neurons. - Motor neurons carry impulses from the brain to the muscles (for
movement) or a gland (for hormone secretion)
what is a reflex arc
Reflex arc produces a very fast response to stimuli and is automatic.
example of how the process works (the three types of neurons)
If you smell pizza when hungry (stimulus), your nose
receptors send impulse through sensory neurons to
brain, where they synapse with interneurons, which then
connect to motor neurons that send the impulse to the
salivary glands to start secretion of saliva (response).
The nervous system is divided into two parts:
the central nervous system and the peripheral nervous system.
Central Nervous System
includes the _____________________
co-ordinates all ________________________________________
Peripheral Nervous System
includes _________________________
is further divided into two separate parts…
Central Nervous System
includes the brain and the spinal cord
co-ordinates all components of the nervous system (both the CNS &
PNS).
Peripheral Nervous System
includes all other nerves in the body
is further divided into two separate parts called somatic nervous system and the Autonomic Nervous System
Somatic Nervous System
what does this system include and what is an example of it
includes motor neurons that are under conscious control and all of
the sensory neurons in your body
Example: sensory neurons in your nose tell your brain your
nose is itchy, and you motor neurons move your muscles for
you to scratch it.
Autonomic Nervous System
what does this system include and what is an example of it
includes only motor neurons that function without conscious control
Example: muscles of your heart that control heart-muscle contraction.
The Autonomic nervous system includes two completely separate
nerves for each body part it controls;
Sympathetic nerves explain what it is
Parasympathetic nerves explain what it is
example of how the two counteract eachother
nerves that prepare the body for danger
nerves that returns the body to a
normal state after a stressful
situation
Fight or flight
Example: sympathetic nerves increase the size of pupils, speed
up heart rate, and slow down digestion. Parasympathetic
nerves decrease size of pupils, slow down heart rate, and
speed up digestion.
example 2, touching hot/ sharp substance
what is this an example of
why does the impulse not go to brain
a sensory neuron senses stimulus –>a tack(sharp) or a hot plate and sends an impulse to spinal cord
a interneuron in the spinal cord transfers the impulse to the motor neuron without involving the brain directly
a motor neuron carries the response impulse to a muscle cell causing it to contract. Brain eventually senses pain although finger is already removed
a reflex arc (automatic reaction)
its faster to go to spinal cord then brain, decreasing the time your body is in danger
