Nervous System Flashcards
Nervous System
Network of nerves transmitting signals throughout the body.
What are the four main functions of the nervous system?
- Reception of general sensory information (touch, pressure, temperature, pain, vibration)
- Receiving and perceiving special sensations (taste, smell, vision, sounds)
- Integration of sensory information from different parts of the body and processing them
- Response generation
Neurons
Specialized cells that gather and transmit information, interpret the information, and react to it.
Dendrites
Dendrites receive information from other neurons and pass the signal received via electrical impulses
Cell body
Contains the nucleus of the neuron.
Axon
Transmit signals on to the other neurons or muscles.
Synapses
Small gap between the axon of one neuron and a dendrite of another neuron that allows the transmission of messages between.
Neurotransmitters
Chemical messengers that move signals across synapses to neighboring dendrites. At dendrite, the chemical signal converts back into electrical signal.
How do neurons communicate with each other?
Electrical Signal: An action potential travels down the axon.
Neurotransmitter Release: At the synaptic terminal, the action potential triggers the release of chemical messengers (neurotransmitters) into the synaptic cleft.
Signal Reception: Neurotransmitters bind to receptors on the receiving neuron’s dendrites, initiating a new electrical signal.
This sequence repeats, transmitting information throughout the nervous system.
What is the myelin sheath?
Myelin sheaths insulate nerve cell axons to prevent electrical impulses from leaking and enabling longer-distance communication.
What are the nodes of Ranvier
Exposed portion of the axon.
How are signals passed?
When neurotransmitters bind to receptors, they open ion channels on the receiving neuron’s membrane. This causes specific ions (like sodium or potassium) to flow in or out, changing the neuron’s voltage. If the voltage change is strong enough, it triggers an action potential, passing the signal along.
Types of Neurons
Motor Neurons
Transmit messages from the brain to the muscles to generate movement.
Types of Neurons
Sensory neurons
Detect light, sound, odour, taste, pressure, heat, and send messages about the stimulants to the brain.
Types of Neurons
Glial Cells
on-neuron cell that supports neutrons to;
* Help support and hold neurons in place
* Protect neurons
* Create insulation called myelin, which helps move nerve impulses
* Repair neurons and help restore neuron function
* Trim out dead neurons
* Regulate neurotransmitters
Types of Glial Cells
Satellite Glial Cells
Respond to chemical messengers to optimize them so that vital responses go as smoothly as possible.
In the sensory nervous system, satellite cells regulate potassium levels and the neurons’ response to evoked potentials without the presence of neurotransmitters.
Types of Glial Cells
Schwann Cells
Schwann cells (neurolemma) of the PNS mirror the role of oligodendrocytes in the central nervous system; they myelinate the axons of neurons and modulate extracellular fluid.
Types of Glial Cells
Microglia
Clear debris and support brain immunity.
Types of Glial Cells
Oligodendrocytes
Manufacture, repair, and arrange myelin sheaths around neuron axons. Oligodendrocytes also support the metabolic needs of the nerve cell axon.
Types of Glial Cells
Ependymal Cells
Produce cerbrospinal fluid (CFS). The microvilli of ependymal cells can absorb CSF and influence its flow and let certain substances in and out of the brain. Depending on where they are located, ependymal cells also help to distribute neurotransmitters and hormones associated with the central nervous system.
Types of Glial Cells
Astrocytes
Maintain the permeability of blood-brain barrier where they sense glucose and ion levels inside the brain and regulate their flow in and out of it.
Nervous System Organization
CNS
Includes the brain and spinal cord.
Cerebralspinal fluid
cushions the brain and spinal cord from injury, transports chemicals, and removes wastes that are produced in the brain
Nervous System Organization
PNS
Connects the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body.
Somatic Nervous System
Controls voluntary movement and reflexes.
Autonomic Nervous System
Regulates involuntary movement in the body. And carries impulses from the central nervous system to the heart and other internal organs.
Sympathetic nervous system
Activates during times of stress or emergency, when the heart rate or breathing rate increases.
Parasympathetic Nervous System
Promotes relaxation and digestion processes.
The Brain
Called the control center of the entire body
Divided into the cerebrum, the cerebellum, and the brain stem
Functions: thought processes (learning), memory, language, speech, voluntary body movements, and sensory perception.
Spinal Cord
Carries nerve signals from the brain to the rest of the body and back.
