Chap 24 The Nervous System and the Senses Flashcards
The vertebrate nervous system is complex?
yes
The nervous system forms what?
a rapid communication network
What is fundamental to the function of the animal nervous system?
rapid communication between cells
What travels so fast the effects seem almost instantaneous in the nervous system?
electrochemical impulses
What are the functional units of the nervous system?
neurons
What do neurons communicate with?
muscles, glands, and other neurons
All neurons have the same basic parts, what are they?
cell body
dendrites
axon
The nervous system is made up of how many classes of neurons?
3
What are the three classes of neurons based on?
their function
What are the different functions of neurons?
sensory
inter
motor
Each neuron in this network sends a message to the next via what?
action potential
What is a neural impulse?
a series of action potentials that spread along the axon
What functions are in the peripheral nervous system?
sensory input
motor response
What functions are in the central nervous system?
sensory integration
What makes up the central nervous system?
brain and spinal cord
Neurons use ions to maintain what?
a resting membrane potential
Chemically what do neurons work to do?
keep K+ concentration higher inside the cell than outside
keep the Na+ concentration higher outside the cell than inside
Stimulation of neurons does what?
opens Na+ channels
The more stimulation the more…?
channels open and for a longer time
Na+ ions enter the cells and collect where doing what?
near the membrane
reverse the charge
The charge inside the neuron is switched from what to what?
negative to positive
Na+ ions accumulate to start…?
an action potential
What happens once the action potential begins?
more Na+ channels open, allowing more Na+ ions into the cell
What happens to the charge on the membrane during an action potential?
now has a positive charge on the inside
What do K+ ions do?
reestablish resting potential within milliseconds
Chemically speaking what does the K+ ion do?
diffuses out of the cell as the Na+ channels close, returning the membrane to its resting potential
After the action potential and during the resting potential what is the charge on the membrane?
the inside of the axon is negative relative to the outside
Neurons pass …
the message along
How do neurons form a communication network?
by passing information to other cells
In what two ways is the formation of the communication network formed?
electrical impulses
chemical signals
Neurotransmitters do what?
pass the message from cell to cell
Do neurons directly touch?
no
Instead of touching what do neurons form?
a structure called a synapse where chemical signals (neurotransmitters) are released
What is a synapse?
a specialized junction between a neuron and another cell
What does the synapse include?
a sending neuron
a synaptic cleft
a receiving cell
What is the sending neuron?
a neuron that releases neurotransmitters
What is the synaptic cleft?
area between neuron membrane and the membrane of the other cell
What is the receiving cell?
could be a neuron, muscle cell, or gland cell
What do action potentials cause?
neurotransmitter release
Neurotransmitters are released where?
into the synaptic cleft as vesicles in the sending neuron and fuse with the cell membrane
The neurotransmitters move across the cleft and do what?
bind to receptor proteins on the receiving cell
What is the equation for reaction time/how fast nerve impulses are?
rxn time = sqrt(2*distance/980)
What are the knowns in the rxn time equation?
gravitational acceleration: 980 cm/s2
distance
The peripheral nervous system consists mainly of what?
nerves
What are nerves?
bundles of axons encased in connective tissue
In most nerves, the sensory and motor nerve fibers are…?
bundled together into a single cable
What do sensory nerves do?
bring sensory info to the brain
What do motor nerves do?
carry instructions for muscle and glands
What is the central nervous system made of?
brains and spinal cord
What two types of nervous tissue make up the central nervous system?
gray matter
white matter
What is gray matter?
neuron cell bodies and dendrites, along with their synapses.
this is where information processing occurs
What is white matter?
myelinated axons that transmit information throughout the central nervous system
What is in the hindbrain?
medulla oblongata
pons
cerebellum
What does the medulla oblongata do?
regulates essential physiological processes such as blood pressure, heartbeat, and breathing
What does the pons do?
connects forebrain with medulla and cerebellum
What does the cerebellum do?
controls posture and balance; coordinated subconscious muscular movements
What does the midbrain do?
relays information about voluntary movements from forebrain to spinal cord
What is in the forebrain?
thalamus
hypothalamus
cerebrum
What does the thalamus do?
processes information and relays it to the cerebrum
What does the hypothalamus do?
homeostatic control of most organs
What is in the cerebrum?
white matter grey matter (cerebral cortex)
What does white matter do in the cerebrum?
transmits information within the brain
What does gray matter do in the cerebrum?
sensory, motor, and association areas
What are the three main structures of the brain?
Forebrain
Midbrain
Hindbrain
The senses do what?
connect the nervous system to the outside world
What are the two types of senses?
General senses
Special senses
What are general senses?
all over the body (e.g. touch, temperature, pain)
What are special senses?
restricted to the head (e.g. hearing and equilibrium, vision, smell, taste)
Sense organs have what?
sensory receptor cells that respond the stimuli
Sensory receptor cells contain what?
a variety of different sensory receptor proteins
Receptors in the skin detect what?
general senses
What do the general senses detect?
touch
temperature
pain
(each of these senses uses its own type of receptors)
Sensing smell and taste is what?
detecting chemicals
What responds to molecules dissolved in a water solution, such as saliva or the moist lining of the nasal passage?
chemoreceptors
What are chemoreceptors located?
in the nose and tongue
Where does the sense of taste begin?
in the taste buds
What do we use taste buds for?
to detect molecules at close range when we put them in our mouth
What are taste buds?
organs in our tongues
The tongues surface is covered in what?
bumps called papillae
What are inside the papillae?
the taste buds
Vision depends on what?
light-sensitive cells
The sense of vision detects what?
light
What happens in vision?
specialized cells in the eye send signals to the brain, which interprets those signals as an image
Where do hearing begin?
in the ears
What happens in hearing?
vibrations in the air are funneled through the auditory canal toward the eardrum.
eardrum vibrations, in turn, vibrate three small middle ear bones?
What are the three small middle ear bones?
hammer
anvil
stirrup
