Nervous Flashcards
Neurons examples:
*Cell body
* Dendrites
* Axon
*Myelin sheath
* Nodes of Ranvier
—gaps between
myelin sheath on the axon fiber
*Cell body
contains nucleus and other
organelles
Dendrites
fan out to receive signals
from sensory receptors or other
neurons
Axon
fibers longer than dendrites,
conducts impulses away from cell body
Myelin sheath
formed from
membranes of tightly spiraled cells,
helps impulses travel faster on long
axons, makes nerves look white
Nodes of Ranvier
gaps between
myelin sheath on the axon fiber
The nerve impulse is dependent on ____ _____
concentration gradients
concentration gradients are maintained by ___-____ _____
sodium-potassium pump
sodium-potassium pump
Actively transports sodium ions (Na+) outside axon and
actively transports potassium ions (K+) inside
* This creates: the charge difference!
- Charge difference
inside of axon negative compared to
outside
* Due to unequal distribution of sodium and potassium
cause the inside to have an overall – charge where the
outside has an overall positive charge.
Action potential
or a nerve impulse uses this charge
difference to trigger quick responses throughout the body
Communication between cells
Dendrites receive the signal –> Signal travels to cell body
and is integrated –> Axons carry the signal out of cell body
–> Signal travels down axon to axon terminal where
neurotransmitters are released across synapse to
dendrites of another neural cell
Synapse
region where axon meets its target cell
Neurotransmitters
chemical messages allowing neurons
to communicate
Presynaptic cell
transmits the signal carrying the
message
Postsynaptic cell
– receives signal from presynaptic cell
Synaptic cleft
space between pre and postsynaptic cell
Nervous system is divided into two parts:
central nervous system (CNS) and
peripheral nervous system (PNS)
central nervous system (CNS)
brain and spinal cord
* White and gray matter organization
* Cerebrum and spinal cord structure
peripheral nervous system (PNS)
autonomic and somatic divisions
peripheral nervous system (PNS) – autonomic
controls smooth & cardiac muscles, glands, functions
“automatically”
PNS somatic divisions
- Controls voluntary motor movements of skeletal muscles
PNS autonomic –> Sympathetic
Activates the fight-or-flight response. Works reciprocally with the
parasympathetic system to maintain homeostasis
PNS autonomic –> Parasympathetic
devoted to resting and digesting
The Cerebrum (Telencephalon) is the most developed area of the brain
and is responsible for ______
higher mental capabilities.
Frontal Lobe
controls motor functions and permits voluntary muscle control; is
responsible for abilities to think, problem solve, speak, and smell
Parietal lobe
receives information from sensory receptor located in the skin and
the taste receptors in the mouth (somatosensory cortex)
Occipital Lobe
Interprets visual input and combines visual images with other
sensory experiences. The optic nerves split.
Temporal lobe
has sensory areas for hearing and smelling. Processes auditory
information and language comprehension
Ventricles:
The
interconnecting spaces that
produce and serve as a
reservoir for cerebrospinal
fluid, which cushions the
brain
Cerebrum
Communicates with, and coordinates the activities of, the other parts of the
brain.
Two halves (hemispheres), each half has a
number of lobes
* Most of the ____ is white matter (long axons of
interneurons taking impulses to and from
_____)
cerebrum
Cerebral cortex
- Ensures coordinated, smooth, voluntary movements
highly convoluted outer layer
of gray matter covering the cerebrum
* Contains over a billion cell bodies
* Region that interprets and initiates sensation,
voluntary movement, and higher thought processes
Diencephalon is composed of:
Thalamus and Hypothalamus
Thalamus
- Receiving end for all sensory input except smell
- Integrates information and sends it to appropriate place in cerebrum
Hypothalamus
- Integrating center that helps maintain homeostasis by regulating sleep, hunger, thirst, body
temperature, and water balance
Brain stem contains ___, ___,____
midbrain, pons, and medulla oblongata
The brain stem connects _____
- Connects rest of the brain to spinal cord
Contains tracts that ascend or descend between spinal cord and higher
brain centers
Midbrain contains
important visual and auditory reflex centers
Pons links ___ with ____, sleep and dreaming
medulla with midbrain
Medulla oblongata contains reflex centers for
regulating heartbeat,
breathing, and vasoconstriction
Reflexes are triggered by a ____ and result in a ____ response.
stimulus, predictable
Reflexes are ___ and ___
fast and invlountary
Reflexes have four to five main components.
1.Receptor
2. Afferent (sensory) neuron
3. Efferent (motor) neuron
4. Effector
Receptor
A receptor detects the appropriate stimulus. pain receptors in the skin
Afferent (sensory) neuron
The sensory neuron conducts the signal from the receptor to the spinal cord.
Afferent (sensory) neuron –> Interneuron
maybe located within the spinal cord to receive the
signal from the sensory neuron.
The presence of an interneuron indicates a
polysynaptic reflex (aka the signal entering the interneuron triggers several responses – reaction to burning is a good example/ all your hand and arm muscles respond).
Efferent (motor) neuron:
The motor neuron receives a signal from either the sensory or interneuron and carries the signal to the effector.
* If the signal passes directly from the sensory neuron to the motor neuron, it is a
monosynaptic reflex (aka a single motor response - knee jerk reaction is a good example).
Effector
muscle response, The effector (what gets acted on) executes the response of the reflex. In the spinal reflexes tested in this activity, the effectors are
skeletal muscles (biceps, triceps, etc).
Several different monosynaptic reflexes:
biceps brachii reflex
triceps brachii reflex
patellar reflex
calcaneal reflex
plantar reflex
