The nervous system I Flashcards
What is a nervous system?
It is a structure that enables us to react/respond to a situation/stimulus
Typical nervous system order
- stimulus presented
- assesment
- preperation
- communication
- response
Response to stimuli in single cells and single-celled organisms is achieved by what?
membrane receptors
Single-celled organisms can detect changes in their environment and respond to stimuli using what?
receptor proteins embedded in their cell membranes
What do individual cells respond via?
receptors and signaling cascades but the responses of individual cells may be accumulated, they are then sent to effector organs whose actions are coordinated by the NS to mediate a response
What does the hippocampal trisynaptic circuit do?
play a role in learning, forming memories and retrieving them
What is neural plasticity?
the ability of the brain or neuron to adjust in response to a new situation or environment
What is short-term memory accessed via?
the hippocampus
What does the hippocampus also play a role in?
long-term memory
Where is long-term memory stored?
the cerebral cortex
What is a nerve set?
a series of interconnected nerve cells
Describe the simplest animals’ nervous systems
they have neurons arranged in nerve nets; no ganglia and no centralisation
Describe a sea star nerve net
they have a nerve net in each arm connected by radial nerves to a central nerve ring
What is cephalization?
the clustering of sensory organs at the front end of the body
What type of animals exhibit cephalization?
bilaterally symmetrical animals
What are cephalized animal’s nervous system like?
nerve net connected by nerve cords connected to ganglia
What does the CNS consist of?
a brain and longitudinal nerve cords
What are ganglia?
segmentally arranged clusters of neurons called ganglia
Ladder system with the development of:
- paired longitudinal nerve cords
- cephalisation and development of paired cerebral ganglia
Insect nervous system:
- cenetralised brain and many organs
- receptors for taste and smell and on antennae and legs
- antennae can detect odors or touch objects
- simple and compound eyes
Earthworm nervous system:
ventral nerve cord developed from fusion of the two longitudinal cords in ladder system, ganglia in each segment coordinate movement and anterior ganglia control more complex behavior
squid nervous system:
more complex behaviors are served by collections of neurons in specialist ganglia that process and integrate information
What is the peripheral nervous system composed of?
nerves and ganglia
What does the spinal cord do?
conveys info from and to the brain and produces reflexes independently of the brain
What do the spinal cord and brain develop from?
the embryonic nerve cord
Where are most cells of the NS found?
the brain and spinal cord
What does the PNS do?
transmits info to and from the CNS and regulates movement and the internal environment
In the PNS what do afferent neurons transmit?
info to the CNS
In the PNS what do efferent neurons transmit?
info away from the CNS
What are the 2 efferent components of the PNS
- motor system
- autonomic nervous system
What does the motor system do in the PNS?
carries signals to skeletal muscles and is voluntary
What does the autonomic nervous system do in the PNS?
regulates smooth and cardiac muscles and is generally involuntary
What is the autonomic nervous system composed of?
sympathetic, parasympathetic, and enteric divisions
What does the sympathetic division of the ANS regulate?
arousal and energy generation(fight or flight)
What does the parasympathetic division of the ANS do?
has antagonistic effects on target organs and promotes calling and a return to “rest and digest” functions
What does the enteric division of the ANS control?
activity of the digestive tract, pancreas, and gallbladder
When does vertebrate brain arise?
during embryonic development
What are the central canal of the spinal cord and the ventricles of the brain filled with?
cerebrospinal fluid
What is the cerebrospinal fluid filtered by?
blood
What is the function of cerebrospinal fluid?
to cushion the brain and spinal cord as well as to provide nutrients and remove wastes
Gray matter:
consists of neuron cell bodies, dendrites, and unmyelinated axons
White matter:
consists of bundles of myelinated axons
Developing arteries invaginate the roof of the ventricle to form what?
choroid fissure
The involuted ependymal cells along with the vessels enlarge into villi and formwhat?
the choroid plexus
Where is the choroid plexus in the adult brain found?
the 3rd, 4th and lateral ventricles
What is the choroid plexus?
networks of capillaries in walls of ventricles
How are the ventricles connected?
Lateral - third - fourth - subarachnoid space
Where is CSF formed?
in choroid plexuses of each lateral ventricle
Function of glia?
have numerous functions to support, and rgulate neurons
Embryonic radial glia form tracks along which newly formed what migrate?
neurons
What do astrocytes do?
induce cells lining capillaries in the CNSto form tight junctions,resulting in a blood-brain barrier and restricting the entry of most substances into the brain
