The Nervous System Flashcards
What are the three main overlapping Functions? Explain.
1) Sensory Input: monitor changes occuring inside and outside of the body using sensory receptors
2) Integration: process and interpret the sensory input to decide on a required action
3) Motor Output: causes a response by activating muscles or glands (effectors)
How many types of cells are there in the nervous system? What are they?
2 types Supporting Cells (Glia) Neurons
What are the functions of Glia?
Functions include support, insulation, and protection
Can Glia transport impulses?
No
Do Glia lose their ability to divide?
No
Do Neurons transport impulses? (Explain why)
Yes. Trasmit impulses in your nervous system from one part of the body to another.
What are nerves composed of?
Many individual neurons bundled together.
What are neurons made up of?
- cell body
- dendrites
- axon
What does the cell body contain?
Nucleus and metabolic center
What does the cell body lack? What does this mean?
Lacks centrioles (doesn’t divide).
What are dendrites?
Projections or extensions that receive signals from other neurons and carry impulses toward the cell body.
Are dendrites high or low branched?
High
What is the axon?
A single, very thin projection from the cell body
Does the axon carry impulses towards or away from the cell body?
Away from the cell body.
How does a axon end?
Ends in a series of branches with slight enlargments on their ends.
What are the enlargments on the end of axons called?
Axon terminals
Neurons conduct electrical impulses taht allow what to detect and respond to stimuli?
Cells, tissues, and organs.
What is the myelin sheath?
Schwann cells in the peripheral nervous system form a shiny white fatty protein wrapped around axon.
What form myelin in the central nervous system?
Oligodendrocytes
What are the three main functions of the myelin sheath?
1) functions in the protection of the nerve fibre
2) serves as a good insulator
3) increases the rate of tranmission of the nerve impulse along the axon
Are their gaps between teh sections of teh myelin sheath? If yes, what are they called?
- Yes
- Nodes of Ranvier
Do impulses jump from node to node at a fast or slow rate?
Very fast rate
Do nerve impulses travel faster along myelinated nerves than nonmyelinated ones?
Myelinated nerves
What do sensory neurons carry impulses from? Where do they carry them to?
Specialized nerve endings called receptors to the spinal cord or brain.
What can these receptors be specialized for? (sensory neurons).
Heat, light, presure, sound waves, chemicals in food, air, etc.
Whare is the cell body of the sensory neuron located? What is it next to?
Clusters called ganglia, next to the spinal cord.
Where do the axons terminate?
Interneurons
Where are interneurons found?
The central nervous system
What is integrative function?
Information is brought together (interpreted to create sensations, thought, add to memory, make decisions, etc.).
What body parts might some interpretation of the sensory information have to occur in before an appropriate responce is decided on?
Spinal cord or brain
who do sensory neurons and other interneurons stimulate?
Interneurons
Interneurons integrate the ___ and relay appropriate ___ to the _____ or other ______.
- date
- impulses
- brain
- motor neurons
What are motor neurons?
Muscles or glands cause reactions or responses to stimuli.
What are effector organs?
muscles or glands cause reactions or responses to stimuli.
What do motor neurons carry?
Impulses from the interneuron in the brain or the spinal cord to an effector that causes a reason in that gland or muscle.
Where is the cell body of a motor neuron located?
Within the spinal cord or brain.
Do motor neurons have long or short axons? Why?
Long lince the impulses travel away from teh cell bodies.
What do individula fibres do?
Very frequently come together to lie side-by-side in collective bundles more commonly known as nerves.
Thousands of individual____make up the nerves leading to and from body areas.
-neurons
What is a reflex arc?
The most basic of nervous responses by orgamisms having a nervous system
What are the five parts of the reflex?
1) the receptor
2) the sensory neuron
3) the interneuron in the spinal cord
4) the motor neuron
5) the effector (muscles)
Many reflex arcs are ______or______actions.
- withdrawal
- protective
Does the brain have to participate in relex arc?
No, but some interneurons do carry impulses to the brain so that it does become aware of an action.
What are some common reflex arcs?
Startle response, blinking, knee jerk, sneezing, coughing, and the changing of pupil size.
Nerve ending before the impulse:
Where is an electric potential?
Between the outside surfac e and the inner area of a neuron.
Before impulse:
This_____develops when an uneven distribution of_____builds up.
- polarization
- ions
On the outside surface, there is a high concentration of what ion?
Sodium (Na+)
On the inside surface, there is a high concentration of what ions?
- potassium (K+)
- chlorine (Cl-)
- negatively charged protein molecules
Diffusion of ____and ____is happening BUT______pumps within the____membrance actively transport____out and___in are working to conteract diffusion.
- K+
- Na+
- sodium-potassium
- neuron
- Na+
- K+
How many Na+ are out for every K+ in?
3 Na+ for every 2 K+.
What happends to the nerve membraine to start an impulse?
- stimulatin initiate an action potential in a nerve cell
- stimulation casue a membrance to become more permeable to the sodium ion due to channels in membrance opening
- rapid inward movement of sodium ions causes carge reversal (depolarization) of membrance
- if stimulus is strong enough, activates neuron to transmit signal called action potential
- when impulse occurs, inward movement of sodium ions cause other channels through plasma membrance to open and K+ ions leave the cells restoring the positive charge outside the cell (repolatization)
The much greater concentration of positive sodium ions on the outside to the potassium ions inside creates what and between what?
Creates a potential difference (about -70 to -90 millivolts) between the positive outside and the negative inside.
The electrochemical reaction or impulse may travel up to how many meters per second in myelinated enrve fivres?
150 m/s
How long, after an impulse passes, does it take to regenerate the original potential?
.001 to .002 seconds
How many impulses can a nerve fibre conduct in one second?
500 to 1000
Once a nerve impulse starts what does it move along? Does it move with stimulation?
- moves along a fibre
- no stimulation
What does a change in membrance permeability trigger?
A change in teh adjoining section as te impulse moves along.
In a myelinated fibre, depolarization occurs only at the what?
-the nodes of Ranvier
What does depolarization of one nerve immediately trigger? Why?
- the next node
- Na+ and K+ cannot diffuse through muelin
What does an impulse actually do in a myelinated fibre as opposed to a non-myelinated fibre?
Jumps from node to node instead of moving continuously.
How many times faster are movements in myelinated fibres?
4 times faster.
What most occur for a neuron to conduct another impulse
Repolarization
What is a synaptic cleft?
neurons are not directly connected to other neurons at their ends. Instead a space exists between them–the synaptic cleft.
How do impulses get across teh sunaptic space?
When impulse reaches the end of an axon, vesicles release a neurotransmitter which diffuses across the synapse to the membrance of the dendrite of the next cell.
What is a neurotransmitter?
chemical released via exocytosis
What does the neurotransmitter do?
alter the permeability of the dendrite’s membrane to sodium ions and a new impulse in initiated.
Where does the neurotransmitter go when its job is finished?
As soon as it is released, some of it is reabsorbed by the dendrite. Enzymes released by the axon terminal break down the rest.
Prevents firing or triggerin gimpulses at the dendrite.
Certain features of___and___result in impulses travelling from neuron to neuron in only one direction.
- neurons
- synapses
Only______releases the chemical transmitters and only____are sensitive to them?
- axon terminals
- dendrites
Impulses only move from_______to______and not the other way around.
- axon terminals
- dendrites
The nervous system of a vertebrate organism consists of____major divisions
2
What are the two divisions?
- central nervous system
- peripheral nervous system
What is the central nervous system made up of?
- brain
- spinal cord
- interneurons carrying info in and out
What kind of centres does the central nervous system have?
integrating and command centers
What does the central nervous system interpret sensory information based on?
past experience and current conditions
What is the peripheral nervous system made up of?
- nerves that carry info between the organs in the body and the central nervous system
- communication lines
How many neurons does the brain contain?
-over 100 billion
How many hemispheres does the brain have?
2
How many protective membrances does the brain have? What are they made up of? What covers the entire organ?
- 3
- connective tissue
- meninges
What do these membranes provide? What is it helped by?
- cushioning effect
- helped by cerebrospinal bluid between second and third layer
What is cerbrospinal fluid secreted by?
clusters of capillaries within the fluid filled cavities of the brain
What does the cerbrospinal fluid also function in?
- nutrient distribution
- waste removal
- movment of hormones
- movement of WBC
What are the three regions of the brain?
- forebrain
- midbrain
- hindbrain
What is the hindbrain made up of?
cerebellum, pons, medulla oblongata
What is teh medulla oblongata? What can injury to this area result in?
Nerve impulses controlling some of the vital body brocesses that are involuntary. Heavy blow or injury to this areas can result in quick death?
What is the pons?
- relay station passing info between cerebellum and cerebrum
- pathway connecting the catious parts of the brain with each other
- important in breathing
What does the cerebellum coordinate?
-muscle actions, balance, posture
How doe we maintain balance?
Muscle “instruction” from the cerebrum and nerve impulses from body parts enter cerebellum where they are coordinated so that we can maintain balance
What is teh cerebellum vital in?
carrying out such asctions auch as jumping or spinning
The cerebellum is also important in____and _____ motor responses?
- learning
- remembering
What is teh midbrain?
major function seems to be that of relaying nerve impulses betweent the forebrain and hindbrain. Relays impulses between the forebrain and the eyes and ears.
What is the brain stem made up of? What does it serve as and why?
- medulla oblongata, pons, and the midbrain
- all infor must pass through on way to higher brain regions so it serves as a filter
What is the largest part of the brain? What makes up most of it? What are the other parts?
-forebrain
-cerebrum
Other parts:
-thalamus
-hypothalamus
What does the cerebrum divide into?
-left and right cerebral hemispheres (from outside each is seen to consist of many folds and creases).
What does the deepest crease create and what does it extend down to?
the two hemispheres. extends down to the corpus callosum.
What is teh corpus callosum?
where nerve bundles cross over from one hemisphere to the other allowing communication betweent the right and left cerebral hemispheres
What do the other deep creases or fissures divide?
each hemisphere into four segments or lobes: frontal, parietal, occipital, temporal.
What are the 3 basic regions in the cerebrum?
1) cerebral cortex (gray matter)
2) Thalamus
3) Hypothalamus
What is the cerebral cortex responsible for?
speech, memory, logic, emotional response, interpretation of voluntary movement, interpretaion of sensation, consciousness
What is the thalamus responsible for and where is it?
- below the cerebrum
- areas where sensory messages to cerebrum pass which enable individuals to become aware of such things as pressure, pain, or temperature extremes
What is the hypothalamus responsible for and where is it located?
- below the thalamus
- regulates the pituitary gland
- controls water adn salt concentration in blood
- regulates body temp, blood rpessure, thirst, sex drive, figh or flight, helps us experience emotions
- maintaisn daily biorhythmus (sleep and hungar)
- biological clock
What is white matter?
fiber tracts (connections)
What is basal nuclei?
patches of gray matter that helps regulate the stopping of voluntary motor activities
What is the spinal cord?
the other major coordinating center and part of the central nervous system
How many way pathway to and from the brain is the spinal cord?
Two-way
The spinal cord is a major what center?
Reflex
What is the spinal cord surronded by?
meminges
How many pairs of spinal nerves arise from the cord? What do they serve as?
- 31 pairs
- serve as a link between all the peripheral nerves and brain
What can damages to the gray matter result in?
flaccid paralysis (nerve impulses do not reach the muscles affected and muscles will atrophy).
What can damage to the white amtter result in?
spastic paralysis (muscles still stimulated by spinal arcs, but movement in involuntary and not controllable and loss of feeling occurs).
What is a nerve?
Structure of neuron fivers outside of the CNS.
How are nerves classified?
according to which way they transmit impulses.
What do mixed nerves contain?
contain both sensory and motor nerurons. All spinal nerves are mixed.
What do sensory nerves carry?
only carry impulses towards the CNS.
What do motor nerves carry?
carry impulses away from the CNS.
What are the two nerves of the peripheral nervous system?
- somatic nerves
- automatic nerves
Many of the ____and _____nerves are____ nerves and are part of the_____system.
- cranial
- spinal
- voluntary
- somatic
What does the somatic system carry? Does the body have conscience control over these?
- messages for voluntary actions back and forth between the body parts and brain.
- yes
What does the somatic system control?
skeletal muscle, bones, and skin
Can the actions or responses carried out by the autonomic nervous system be conscieously controlled?
no (happen automatically or involuntarily)
What does the autonomic system regulate and how?
conditions in the internal environment inside the body by controlling actions of organs or glands.
What kind of muscle is the autonomic nerves known to control?
- smooth muscle (surrounds organs and blood vessels.
- known to control cardiac muscle (heart muscle)
What organs does the autonomic nervous system control?
organs of the digestive, circulatory, excretory, adn endocrine systems
What does the autonomic system work to maintain?
relative stability of your internal environment (breathing rate, stomach secretions).
How many sets of neurons with opposing effects on body organs make up the autonomic nervous system? What are they?
Two:
- sympathetic division
- parasympathetic division
Where do nerves of the sympathetic system come from?
-come from thoracic and lumbar vertebrae
What is the sympathetic system involved in?
all internal adjustments that prepares the body for action or increased levels of stress
How do nerves of the parasympathetic system leave the brain?
directly or from either the cervical or caudal sections of the spinal cord.
What do the parasympathetic nerves carry out?
Impulses that return a body to normal funcctioning after a period of stress is over. Allows us to conserve energy.
What do sympathetic and parasympathetic nerves do to eachother? What is this an example of?
- counterbalance eachother activities
- homeostasis occuring within the body
Why are fin adjustments continually being made? (sympathetic and parasympathetic).
So that glands and organs are functioning at levels appropriate to a body at a particular time.
