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.