Nervous System Flashcards
What does the nervous system send and receive?
Information about the activities within the body
What does the nervous system monitor
It monitors and responds to changes in the environment
What is a stimulus?
a change in the environment that causes a response
What are some involuntary responses to a stimulus?
increased heart rate, pupil response to light, blinking, sneezing, and knee jerk
neuron
a message carrying cell
About how many messages make their way through the body each second?
100s
What is another name for neuron?
nerve cells
Nerve cells
the basic units of structure and function in the nervous system
What is unique about neurons?
They cannot regenerate (be replaced if damaged or destroyed)
What part of the neuron is the “door” into the neuron?
the dendrites
How do things exit the neuron?
through the axon terminals
neurotransmitter
ferries (or moves) nerve impulses across the synapse
What happens as the impulse nears the synapse?
a chemical signal pours from the ends of the neuron (axon terminals)
What happens to the electrical signal when the chemical signal takes over?
The electrical signal shuts down
What is the job of the chemical signal?
It takes the impulse to the next neuron…moving across the synapse
What is a synapse?
a gap between neurons
What happens to this electrical/chemical signal process?
It repeats until the impulse reaches its destination
What crosses the synapse?
a neurotransmitter and salt
What carries the electrical signal?
an axon
What is the job of the myelin sheath?
it protects the axon and facilitates conduction of electrical signals
What are the parts of a neuron?
cell body, dendrites, axon
cell body
contains nucleus which controls the cell’s activities
dendrites
carry messages to many cell bodies
axon
carries messages away from only one cell body (1mm to 1 m)
What are axon terminals?
ends of axons
What is the job of axon terminals?
they pass on the message to the dendrites of another neuron
receptors
receive information from your surroundings
What are the 3 types of neurons in the Nervous System?
- sensory, 2. interneurons, 3. motor neurons
sensory neurons
take messages from receptor to spinal cord and brain
interneurons
found in the brain, connects sensory to motor
motor neurons
take messages from the brain and spinal cord to a muscle or gland cell
effector
the cell that is stimulated, or affected, by the motor neuron
nerve impulse
a pathway that the messages take from the sensory neurons to the interneurons to the motor neurons
What form to the nerve impulses take as they travel along the neurons?
electrical and chemical signals
The impulses enter the neuron through what?
the dendrites (door)
The impulses travel along the length of what?
the axon (exit)
How fast can impulses travel?
120 m/s
synapse
gape between the ends of neurons
What are the two main divisions of the nervous system?
- central nervous system 2. peripheral nervous system
central nervous system (CNS)
brain and spinal cord….controls the center of the body
peripheral nervous system
network of nerves outside the central nervous system
How can you describe the activities within the CNS
they are very complex
brain
control center that transmits and receives messages
spinal cord
link between the brain and the rest of the body
Why does most of the brain appear grey?
as a result of the presence of the cell bodies of billions of neurons
What is under the grey matter of the brain?
white material…made of bundles of axons
What is the mass of the brain?
1.4 kg
What protects the brain?
the skull (cranium)
meninges
three layers of connective tissue that protect and nourish the brain
inner layer
pia matter…a thin inner layer that adheres to the folds
middle layer (arachnoid)
separated from the inner layer by a watery fluid that funtions as a shock absorber
outer layer
dura matter…makes contact with the skull….think and tough for protection
meningitis
infection of the meninges (is often fatal)
What is the layer order of the head
skin of scalp, periosteum, bone of skull, periosteal layer, meningeal layer
vertebra
a series of bones that protect the spinal cord
How many spinal nerves are there?
31
What is the job of the spinal nerves
Connect the brain with the rest of the nervous system
reflex
simple response to a stimulus
Where are interneurons located?
located in the spinal cord
What is the job of the interneurons?
they receive the nerve impulse and send the impulse to the motor neurons
What is the job of the motor neurons?
they stimulate the effectors
Why is it possible for reflexes to be lightning fast and automatic?
the impulses travel only to the spinal cord
cerebrum
(drum) largest part of the brain
What does the cerebrum look like?
lines with grooves and folds that increase the surface area
How is the cerebrum divided?
into two hemisphere
What are the jobs of the two hemispheres of the brain
each hemisphere controls movement of the OPPOSITE side of the body
What is the job of the cerebrum?
it is the area of learning, intelligence, voluntary motion, thinking and cognitive ability
cerebellum
(belle) below and behind the cerebrum
What is the second largest part of the brain?
cerebellum
What is the job of the cerebellum?
SUBCONSCIOUS movement of skeletal muscles (blinking), maintains balance
medulla oblongata
(dull) below the cerebellum
What does the medulla oblongata connect?
the brain to the spinal cord
What is the job of the medulla oblongata?
controls INVOLUNTARY actions-heartbeat, breathing, reflex centers for coughing and swallowing
What is the job of the peripheral nervous system?
link between the central nervous system and the rest of the body
The peripheral nervous system is made up of how many nerves?
43 pairs of nerves (31 spinal nerves, 12 cranial nerves)
Where do the peripheral nerves run from?
the brain and spinal cord to the ORGANS throughout the rest of the body
autonomic nervous system
controls body functions that are involuntary (digestion, circulatino)
How many different groups can the autonomic nervous system be divided into?
2 groups
What are the jobs of each group int he autonomic nervous system?
- triggers and action by an organ 2. slows down or stops the action
What are some examples of homeostasis?
perfect balance, sweating until you have cooled off
How do the nerves of the autonomic nervous system work?
they work AGAINST each other to keep bodily activities in homeostatis
