Test 7- Nervous System Flashcards
Whats the function of the nervous system
To coordinate and regulate the functioning of the body’s other systems
What are the two main branches of the nervous system and what sets them apart
Central nervous system includes brain and spinal cord
Peripheral nervous system includes spinal and cranial nerves
Which way do dendrites and axons carry nerve impulses
Dendrites: towards cell body
Axon: away from cell body
What do neuroglia cells do and what are two of them
Support and nourish neurons, maintain homeostasis, and form myelin
Oligodendrocytes and schwaan
What do neurons do and what are the three types
Transmit nerve impulses between parts of the nervous system
Sensory, interneuron, and motor
What type of endings do sensory neurons have and what do they do, in which areas are sensory neurons in the cns and pns, what is it myelinated by
Have specialized ending called sensory receptors near dendrite end, which detect changes in the environment and carry the messages to the cns, detecting changes in temperature and pressure
Most of sensory neuron in pns, while axon terminal is in cns
Myelinated by schwaan cells
What is the function of the interneuron and which parts are found in the cns and pns, what is it myelinated by
Found completely in the cns
Receives messages from sensory neurons, sums up the messages received and communicates with motor neurons
Myelinated by oligodendrocytes
What do motor neurons do, which parts are in the cns and pns, and what are they myelinated by
Myelinated by schwaan cells
Carry the message from the cns to an effector (muscle, organ, glands)
Cell body in cns, axon and axon terminal in pns
What does myelin do, what is myelin, where is it from
Lipids found in the membranes of schwaan cells
Increases speed of nerve impulse transmissions and aid in nerve regeneration in the pns
Whatre nodes of ranvier
Gaps between myelin sheath that allows for nerve impulses to jump from one to the other
Whats saltatory conduction
Faster transmission speeds via nodes of ranvier
Which systems are schwaan and oligodendrocytes found
Schwaan found in pns, oligodendrocytes found in cns
Whatre tracts and nerves
Tracts: bundles of myelinated axons in cns (white matter)
Nerves: bundles of myelinated axons and dendrites in the pns
What is an action potential and what does it do
A rapid change in polarity across an axon
Carries the message from one end of the neuron to the other
Whatre the four steps in nerve impulses
Resting potential, depolarization, repolarization, recovery/refractory period
What is the resting potential of a neuron and why is it that way
-70 mv
Because theres more na+ outside (causing it to be more negative inside), and theres cl- and large, negatively charged proteins inside
Where is na+ and k+ found during resting potential and during repolarization
Resting: k+ inside, na+ outside
Repolarization: k+ outside, na+ inside
What happens during depolarization and why does this happen
How negative does it start and end in this step
Na+ channels open after threshold is reached, na+ enters due to concentration and electrochemical gradient, making the neuron more positive.
Starts at -55, ends at 40
How negative does a neuron need to be for na+, k+ ca2+ channels to open
Na+: -55 mv
K+: 40 mv
Ca 2+: -55 mv
How negative does a neuron need to be for na+, k+, and sodium potassium pump to close
Na+: 40 mv
K+: -70
Pump: -70
What happens during repolarization and why
K+ channels open after na+ closes, k+ leaves neurons due to concentration and electrochemical gradient
Neuron becomes more negative
Why does hyperpolarization occur and at what negativity
-85
During repolarization, k+ channels are slow to close at -70 mv, causing more k+ to rush out and making it more negative than needed
What happens during the recovery period, how many na+ are moved out and how many k+ are moved in
Sodium potassium pump moves 3 na+ out, 2k+ in because ions are on wrong side of neuron
Restores ion distribution so nerve impulse can start again
Whats a synapse
A region where the axon of one neuron is close to/ communicates with the cell body/dendrite of another
What do neurotransmitters do
Carry the action potential across the synaptic cleft
How do voltage gated ca 2+ channels open
Once the nerve impulse reaches the axon terminal of the first neuron, depolarizes it
What does ca2+ do
Diffuse into the neuron via channel, interacting with proteins that cause vesicles with neurotransmitters to merge with the presynaptic membrane
How do neurotransmitters enter the synaptic cleft
Via exocytosis
How do neurotransmitters move across the cleft
Diffuses across the cleft to the receptors on the na+ channels on the post synaptic membrane (Dendrite/ cell body of next neuron)
What happens when nts bind to the receptors of the post synaptic membrane
Alters the potential of post synaptiv membrane depending on the nt and receptor
Whatre the two types of nts and what do they do
Excitatory: cause neuron to get closer to its threshold required in order for it to fire by opening na+ channels (becomes more positive/depolarize)
Inhibitory: cause neuron to get further away from its threshold by opening up K+ or Cl- channels (becomes more negative/repolarize)
What happens to the neurotransmitters after theyve done their job
Reabsorbed by presynaptic membrane/digested by enzymes in the synaptic cleft
Whatre the two neurotransmitters used and where are they used
Acetylcholine (ach) used in somatic and autonomic systems of the pns
Norepinephrine used in the sympathetic division of the autonomic system
What breaks down ach
Acetylcholinesterase
What is different about the action potential for stronger stimuli
More neurons will fire, neurons will fire more frequently
How can drugs affect the nervous system and synapses
1.Stimulates release of nts
2.Blocks the release of nts
3.Combines with nts to prevent them from being broken down by enzyme
4.Mimics nts, binding to receptors (Causing impulses/blocks nts from binding)
5. Prevents uptake of nt from presynaptic membrane (neuron continues to fire=continuous impulses)
What happens when excitatory and inhibitory nts are blocked
Excitatory: paralysis
Inhibitory: convulsions
Where does the spinal cord leave the skull from
From the foramen magnum
Wheres cerebrospinal fluid found and what does it do
Cushions brain and spinal cord
Between the meninges, in brain ventricles, and central canal
Whatre the meninges
Protective three membrane layers around the brain and spinal cord
For spinal cord, is gray matter on the inside or the outside, what is it also called
The inside
The cortex
For the brain, is gray matter on the inside or the outside
Outside
What does the gray matter of the spinal cord contain, what is it responsible for
Where synapses occur, where commmunication between sensory and motor neurons occurs
Contains cell bodies/dendrites of motor neurons, axons of sensory neurons, and cell bodies of interneurons
Axons found here are nonmyelinated
What is the white matter in the spinal cord responsible for, what does it contain
Interneurons bundled together in tracts (just the myelinated axons)
Communication between the brain and pns
Whatre the four main parts of the brain
Cerebrum, diencephalon, cerebellum, brain stem
what is the cerbral cortex responsible for
For sensation, voluntary movement, and thought
What divides the l and r hemispheres of the cerebrum
The longitudinal fissure
Whats different about the l and r hemisphere
L: more specific
R: more as a whole
Whatre the four lobes of the cerebrum
Frontal, parietal, occipital, temporal
What is the frontal lobe responsible for and contain
Contains the primary motor cortex, controlling voluntary skeletal muscles
Allows humans to thnk critically and formulate appropriate behaviours (behaviour/emotional control center, responsible for personality)
Contains brocas area (only in lh), which refines grammar and controls speech
What does the parietal lobe do and contain
Contains the somatosensory cortex, receives sensory info (touch, temp., pain), from skin and skeletal muscles
Analyzes information from skin, muscles, and cerebellum
What does the homunculus represent in the brain and why
Somatosensory cortex
Represents how the cortex receives more input from some areas (the hands, lips) than others
What is the occipital lobe for
For sight and recognizing sights by comparing
What is the temporal lobe for
For receiving info from the ears and nose, recognizing sounds by comparing, and understandning written and spoken word via the wenickes area (lh only)
What does the cerebellum do
Receives sensory input from joints and muscles
Controls balance and maintains posture
Works with cerebral (motor) cortex to ensure smooth complex muscle movement, also working with the parietal and frontal lobe
What does the diencephalon contain
Hypothalamus, thalamus, pineal gland
What does the thalamus do
Receives sensory input (taste, audio, visual), from pns and sends it to the cerebrum (Relay station)
Involved in higher mental functions like memory and emotions with the limbic system
What does the hypothalamus do and control, what does it regulate
Controls the pituitary glands
Maintains homeostasis by secreting hormones
Regulates sleep, thirst, hunger, body temperature, blood pressure, water balance
What does the pineal gland do
Secrete melatonin, regulating the bodys sleep and wake cycles
What does the brainstem contain
Midbrain, pons, medulla oblongata
What does the midbrain do and contain
Relay station (passes info) between the cerebrum and the spinal cord/cerebellum
Contains reflex processing centers for certain visual and auditory responses
What do the pons do and contain
Contains axons that travel from the cerebellum to the rest of the cns
Works with medulla oblongata to control breathing
What does the medulla oblongata do and what reflex centers does it have
Controls many reflex centers for heartbeat, respiration, vasoconstriction, coughing, swalllowing, vomiting, sneezing, hiccuping
What does the corpus callosum do/ is
Is a bridge of white matter, that passes info between the left and right cerebral hemisphere
What does the limbic system do and contain
Contains the hippocampus and amygdala
Functions in learning and memory
Amygdala also functions in responding to and displaying anger and fear
Prompts release of adrenaline from adrenal glands
How many cranial nerves are there and what neurons do they contain
12 pairs
Sensory, motor, mixed
What do cranial nerves operate
Brain, neck, face, internal organs
How many spinal nerves are there and what neurons do they contain, what branches do they have
31 pairs
All mixed
Dorsal (for sensory neurons), and ventral (for motor)
What does the somatic nervous system operate, which nt is used
The skin, muscles, and tendons
Ach
Are ach and ne excitatory or inhibitory
Excitatory
What does the autonomic system operate
Heart, glands, internal organs
Whats the pathway of information in the autonomic system
Receptor/sensory neuron
Motor (preganglionic)
Ach
Ganglion
Motor (postganglionic)
Ach/ne
Effector
Where do nerves leave in the sympathetic division
Leaves the middle (thoracic lumbar) part of the spinal cord
Is the preganglionic motor neuron shorter or longer in the sympathetic division, what nts are used
Shorter, ach and ne
What does the adrenal medulla release, why, and in what division
Sympathetic
Stimulated by neuron
Release norepinephrine and adrenaline
Where do nerves leave in the parasympathetic division
Leave the cranium/ sacral (bottom) of spinal cord
Is the preganglionic motor neuron shorter or longer in the parasympathetic division
Longer
Where is the ganglia often found in the parasympathetic division
Above the effector/organ
What nt is used in the parasympathetic division
Ach only
What is special about a reflex, is it in the gray or white matter
It doesnt involve the brain, is only in the gray matter of the spinal cord
