The Nervous System Flashcards
What does the nervous system do?
The central nervous system (CNS) coordinates a response
It is where all the information from the sense organs is sent, and where reflex responses and other actions are coordinated
What does the CNS consist of
It consists of the brain and spinal chord
What are the 3 main parts of a nervous response
Stimulus - a chance is detected in the environment
Sensory receptors - group of cells that detect the sensory change
Effectors - muscle glands that respond to the sensory change
What is the structure of a motor neurone
- dendraites
- cell body below dendrites
- axon length
- made up of axon running through myelin sheath
- nodes of ranvier
- axon terminal
What is the structure of a sensory neurone
Dendrites at the end
Cell body located in the axon terminal, between the Schwann cells
What do sensory receptors do
They are a group of cells that detect the sensory change
What is the function of effectors
They are muscle or glands that work together to respond to a nervous impulse/change in stimuli
What do receptor cells do
They change the stimulus form the surrounding to electrical impulses, different receptors detect different stimulus
Function of sensory neurones
Carry electrical impulses from receptor cells to the CNS
What do relay neurones do
Carey electrical impulses from sensory neurones to the motor neurones
What does the motor neurone do
Carries electrical impulses from the CNS to the effectors
How does the impulse travel through a neurone
The impulse goes from the dendrites to to the axon
What is a reflex action
A reflex action is an automatic (involuntary) reaction, which occur without the impulse being transmitted to the Brain
How does a reflex action occur
Stimulus -> receptor cells -> sensory neurone -> spinal chord -> motor neurone -> effector -> response
How does a regular reaction occur
Stimulus -> receptor cells -> sensory neurone -> spinal chord -> brain -> spinal chord -> motor neurone -> effector -> response
Why is a reflex action faster than a voluntary action
A reflex action is coordinated in the spinal chord, meaning that the impulse doesn’t not need to travel to the brain, meaning it is able to be carried out much faster than a voluntary action
What do the receptor cells do
They change the stimulus (change in surrounding) into electrical impulses. Different receptors detect different stimuli
How is an impulse carried from one neurone to another
1) The impulse travels along the axon and is sped up by the myelin sheath.
2) When it reaches the end of the axon, the impulse arrives at a place called the axon terminal, and the gap between this neuron and the next is called the synaptic cleft.
3) The neurons never touch and instead communicate by releasing chemicals through the synaptic cleft.
4) At the axon terminal, the arrival of the impulse causes special structures called synaptic vesicles to release chemicals called neurotransmitters.
5) These neurotransmitters diffuse across the synaptic cleft to start the impulse in the next neuron
How do relay neurones carry implisees from the sensory neurone to the motor neurone
1) Stimulus Detection: A sensory neuron detects a stimulus (like heat or light) and generates an electrical signal called an action potential.
2) Transmission to CNS: The sensory neuron transmits this action potential along its axon to the central nervous system (CNS), which includes the brain and spinal cord.
3) Synapse Connection: When the action potential reaches the end of the sensory neuron, it crosses a small gap called a synapse by releasing chemicals known as neurotransmitters.
4) Relay Neuron Activation: The neurotransmitters bind to receptors on a relay neuron. This binding can trigger an action potential in the relay neuron, allowing it to send the signal forward.
5) Continuing the Signal: The relay neuron processes the information and quickly transmits the action potential along its axon toward a motor neuron.
6) Motor Neuron Response: Finally, the motor neuron receives the impulse and sends it to the appropriate muscle or gland, causing a reaction (like moving away from heat).
Why does the sensory neurone not connect to the motor neurone directly
Relay neurones serve as connections that allow for more flexible responses and modulation, which would not be possible if the connection was direct.
What is the PNS
- peripheral nervous system
- detects a stimulus from its surrounding environment
- part of nervous system other than brain and spinal chord
What are effectors
Muscles or glands that respond to a change in stimuli. Muscles contract, and glands respond by releasing hormones
What’s the name of the gal between two neurons
Synapse
Describe the sequence of events that Happen during a simple reflex arc
-> sensory receptors detect change in stimulus
-> send electrical impulse along sensory neurones to the CNS
-> in the spinal chord, sensory neurone synapses with motor neurone and the CNS coordinates a response
-> motor neurone then transmits electrical impulses across motor nierones
-> the motor neurones send signals to effectors (such as muscle or gland)
-> response takes place by the effector
