Nervous System Flashcards
What is the purpose of the nervous system?
It is responsible for maintaining homeostasis in the body, with 5 general functions:
1. Reception: receiving info from other external and internal sources
2. Conduction: the passage of info around the body or brain
3. Interpretation: organizing sensory input (past or present sensation)
4. Organization: coordinating thought or actions in response to stimulus
5. Transmission: sending info to execute reaction to stimulus
Endocrine system VS Nervous System
The nervous system is fast acting and short lasting while the endocrine system is long-acting and long lasting
What is the Central Nervous system
Made up of the brain and the spinal cord. It is the body’s coordinating center for chemical and mechanical actions. Responsible for processing and organizing information.
What is the peripheral nervous system?
Consists of nerves that carry information between the organs of the body and the CNS.
What are the two major divisions of the PNS?
- Somatic Nervous system - contains all the nerves that serve the musculoskeletal system and the sensory organs, actions are conscious and deliberate.
- Autonomic Nervous System - Contains all the nerves that serve the internal organ,actions are unconscious and autonomic.
What are the two divisions of the autonomic nervous system?
Sympathetic - responsible for the flight, fight or freeze response. STRESS. Dialton of pupils, increased heart and breathing rate, slowed digestion, etc.
Parasympathetic - responsible for the relaxation response (after flight or freeze). PEACE. (Rest and Digest)
What is the sensory neuron?
Carries impulses to the central nervous system from receptors
What are motor neurons?
Carries impulses from the brain (CNS) to the muscles and glands (effector)
What are interneurons?
The neuron of thE CNS connects with the sensory, motor and other interneurons to relay sensory input with motor output. Carries impulses within the central nervous system
What is a dendrite?
Receives stimulus carries impulses toward the cell body
What is the cell body
It contains the neucleus
What is the axon?
Carries impulses away from the body (transmits the impulse)
What are Schwann cells?
They produce myelin cells
What is the myelin sheath?
Insulated covering over the axon of a nerve cell and it speeds up transmission.
What are the nodes of Ranvier?
gaps between sections of myelin sheath along the axon
What is the neurilemma?
Regenerates damaged axons asnd a delicate memebrane that surrounds the axon of some nerve cells
What is the synapse?
A region between neurons, or between neurons and receptors; synaptic cleft
What is grey matter?
Contains unmyelinated nerve cells (slower transmission)
What is white matter
Contains myelinated nerve cells (faster transmission)
What are reflexes (reflex arc) and how do they work
They are automatic and involuntary responses that happen so quickly that the brain is not involved, a pathway of conduction called a reflex arc. This begins with the SENSORY RECEPTOR - modified dendrites activated by the stimulus. Then the SENSORY NEURON - carries the impulse to the CNS. the INTERNEURON - connects other neurons to integrate sensory input with motor output. So then the MOTOR NEURON - carries info from the CNS to an effector. And finally the EFFECTOR - produces a physiological response when stimulated by the nerve impulse.
How does an impulse travel down a neuron?
The stages of actions potential begin at:
1. Resting potential with a polarized membrane. More potassium inside the membrane and more sodium on the outside. As the sodium-potassium pump that pumps Na and K against their gradient to maintain a polarized membrane
2. Depolarization then happens where there is a change that causes the Sodium ion gates to open causing Na ions to rush in, where the outside is now less positive.
3. Repolarization then happens when the electrical potential causes the potassium channels to open so the potassium rushes out of the cell
4. For the neuron to fire again resting potential needs to be restored and the K and Na gradients need to be restored. So K ions are pumped back into and Na ions are pumped out.
And then resting potential is restored
What is the all or none response?
If the complete threshold level is not reached the action potential will not occur. It only happens if the threshold potential is met or exceeded.
What are Threshold levels?
Minimum depolarization that must be met before sufficient voltage-gated Na ion channels will open to launch
What is summation?
Whether or not the neuron fires depends upon the net effect of either the exhibitory or inhibitory neurotransmitters received. If there is adequate excitation to reach threshold the neuron will fire.
