Nervous System Flashcards
Nervous System
organ system that carries signals throughout the body. Divided into 2 systems: CNS and PNS
Central Nervous System
Nerve tissue in the brain and spinal cord
Peripheral Nervous System
Nerve tissues outside the central nervous system
Neurons
Nerve cells that transmit electrical impulses that travel in one direction; from the dendrites to the axon terminal. Connect to and from muscles and glands
Axon
Long, narrow ‘arm’ that carries electrical signals (like wires)
Dendrites
Short, branched fibers that transmits signals to other cells
Cell body
Contains the nucleus and majority of the organelles and cytoplasm
Motor Neurons
4th in the stimulus-response model. Carry messages from CNS to effectors
Myelin
A white, fatty substance that encases the axon, allowing messages to pass along it and insulating it much like the plastic coating on electrical wire
Axon terminal
Nerve endings
Muscle fibres
In motor neurons, the endings connect directly to muscle fibres instead of a sensory receptor
Sensory receptor
Specialized nerve endings in sensory neurons that are sensitive to a particular stimuli such as heat, pressure or light
Synapse
The space between the neurons
Neurotransmitter
An electrical signal that goes through the neurons. When it travels through the synapse, it is converted to a chemical. It carries the message from the axon of one neuron to the dendrite of the next neuron.
Nerves
Neurons that are bundles together
White matter
Parts of the CNS containing neurons covered in myelin
Grey matter
Parts of the CNA that are mainly cell bodies
Synaptic clef
Gap between the cells
How many neurons does the human brain contain
about 100 billion
Volume of the human brain
1200-1400 mL
MRI (magnetic resonance imaging)
Uses strong magnetic fields to distinguish different types of body tissue.
Cerebrum
Controls the conscious thoughts, the intentional movement of every body part, and receives sensory messages from each body part. It occupies more than 80% of the brain and contains over 10 billion neurons. It has many folds that increases the surface area by 3.
Left and right hemisphere of cerebrum
LHS of cerebrum controls RHS of body and vice versa in actions such as running or hitting a ball. Both sides are used for most activities. One side usually dominates in a task.
Cerebellum
At the base of the cerebrum where your skull curves inwards. Responsible for coordination and balance.
Medulla
Lower part of the brain stem where the spinal cord widens. Controls the body’s vital functions (breathing, blood pressure, heart rate)
Cranium
Protective bone that covers the brain
Vertebrae
Protects the spinal cord
Receptor
1st in the stimulus-response model. Stimulates the sensory nerves
Sensory nerves
2nd in the stimulus-response model. Send a message to the brain. Carry messages from cells in receptors (eg. eyes or tounge) to the brain and spinal cord
Brain
3rd in the stimulus-response model. Controls you
Relay neurons
Pass the message to motor neurons in the spinal cord. 3rd in the reflex arc
Stimulus
What causes your receptors to feel stuff e.g. sun causes temperature receptors so feel hot
Effectors
Impulses are sent to them after relay neurons pass the message along. Muscles or glands - tissues that secrete chemicals - that put the messages into effect. 4th in the reflex arc. 5th in the stimuli-response model.
