Lecture 11: Nervous Systems Flashcards
Describe a neuron
Neurons are specialized nerve cells of the nervous system
Describe dendrites and their role
branch-like filaments attached to a cell body that receive nerve signals from connecting cells (can be other nerve cells too)
Describe the cell body and its role
contains the nucleus and most organelles
Describe axons and their role
the long extension from an individual nerve cell that transmits signals received by dendrites to other neurons
Describe myelin sheath and its role
A tissue that surrounds axons of many neurons to function as insulation. By providing insulation, myelin sheaths allow axons to transfer neurons much faster
Define brain
A group of neurons forming a higher-order processing unit and is the location of the integration (analysis and interpretation) of sensory information
What are the 3 basic stages of information processing? Describe them
- Sensory input: sensory receptors (eyes) see the stimulus
- Integration: processing unit (brain or in simpler organisms, ganglion) analyzes and interprets the stimulus and decides a response
- Motor output: processing unit sends a signal to muscles to perform an action
What are the 3 main types of neurons? Define structure and function
- interneuron: brain and spinal column neurons
- highly branched axons and dendrites to receive a ton of information (more SA). - sensory neuron (afferent):
- cell body is part way along the axon - motor neuron (efferent):
- highly branched dendrites for receiving a lot of information from brain and carrying info down the axon
Describe the central nervous system and outline its role
The central nervous system is made up of steps:
- sensory receptors perceive external stimulus
- afferent/sensory neurons send information of stimulus to the brain
- central nervous system receives the message and makes a decision in the processing unit
- efferent or motor neurons of the SOMATIC nervous system perform an action.
Sensory system –> central nervous system –> somatic nervous system
Describe the peripheral nervous system and outline its role
Includes:
- sensory system
- somatic nervous system
- autonomic nervous system
function: transmits information to and from the CNS.
In the second stage of information processing (Integration), which neurons are at work? And what is the outcome?
INTERNEURONS in the brain analyze and interpret sensory information to initiate MOTOR RESPONSES (basically, make a decision).
In the third stage of information processing (motor output), what occurs? which neurons are activated? what is the outcome?
Information from the processing unit (brain) is carried by MOTOR NEURONS to trigger EFFECTORS to performing an action.
Describe the somatic nervous system and outline its role
movements directed by the CNS that are typically under voluntary control (includes reflexes)
Describe the autonomic nervous system and outline its role
one of the PNS.
coordinates the INVOLUNTARY movement and controls movements of the smooth and cardiac muscles
Describe the sympathetic nervous system and outline its role
the REACTIONARY division of the ANS.
it is involved in the fight or flight responses
Describe the parasympathetic nervous system and outline its role
the COOL DOWN division of the ANS.
It is involved in maintenance and calming and balances out the sympathetic reactions
What is a reflex? What is a reflex’s significance to survival?
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Outline a cnidarian nervous system
- radial symmetry
do not contain an actual CNS, but instead their interconnected nerve cells form a DIFFUSE NERVE NET
Function of nerve net: controls contraction and expansion of GVC to help with digestion and/or movement of motile cnidarians (jellies) by pulling in or pushing out water of the GVC.
Outline a platyhelminthes nervous system
flatworms have the simplest CNS.
- a simple brain and two longitudinal nerve cords
Outline an annelid nervous system
segmented invertebrates like annelids and arthropods have more complex brains
and a SINGLE VENTRAL NERVE CORD (along the front body/stomach) with GANGLIA in EACH SEGMENT to control the different segments
ganglia function as the control centers to process information and coordinate movement
Outline an arthropod nervous system
- bilateral symmetry
- much more complex nervous system that includes a CNS
- axons bundled into nerves that direct the flow of information
- cephalization: clustering of sensory and interneurons in the head of the body (might not be a brain, but some sort of processing unit)
Outline a vertebrate/chordates nervous system
vertebrates have the most complex nervous systems (because they have the most complex movements)
CNS with a complex BRAIN with regional specialization (ex. brainstem, central cortex, regions of the brain) and a DORSAL CORD (spinal cord)
A PNS with nerves and ganglia that coordinate muscle contractions
How do nerve cells transmit signals?
- signals can be received by either dendrites or the cell body itself.
- The signals travel along axons as an ELECTRICAL IMPULSE until they reach a SYNAPSE
- when an electrical impulse reaches the end of an axon, it triggers the release of neurotransmitters
- neurotransmitter connects to and then sends the signal across the synaptic cleft between two cells
- neurotransmitter binds to a transport protein on the receiving cell’s membrane
- the binding triggers the protein to open channels to allow the charged ions to move into the new cell
T or F: the structure of a neuron varies according to their function? why/why not?
TRUE. The structure of a neuron is highly related to its function
