The nervous system
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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