Nervous System
Belen Esparza
Period: 2
Major Subdividions of the Nervous Systems
Classification of Neurons
Compare & Contrast the Autonomic Nervous System
Spinal Nerves
The main branches of spinal nerves, except in the thoracic region, form networks called plexus
Action Potential & Nerve Impulse
Major Functions of the Nervous System
Neurotransmitters
Major Parts and Functions of the Spinal Cord
Based on Structure
Based on Function
Central Nervous Systems
Responsible for integration of information and decision-making
Brain - receives and processes sensory information
Spinal cord - conducts signals to and from the brain, controls reflex activities
Peripheral Nervous Systems
Connect the CNS to the rest of body
Autonomic Nervous System
Controls involuntary effectors
(smooth & cardiac muscles/glands)
Somatic Nervous System
Controls voluntary skeletal muscles
Motor Neurons
Location: In the spinal cord
Function: Conduct impulses to effectors (muscles/glands
Interneurons
Location: Multipolar neurons lying within the CNS
Function: Interconnect sensory with motor neurons, and are located in the Central Nervous System.
Sensory Neurons
Location: Outside the spinal cord .
Function: Conduct impulses from peripheral receptors to the CNS; usually unipolar, although some are bipolar.
1)Action potential passes along the axon and over the surface of the synaptic knob
General Functions
General Aspects
Sensory Input
Integration
Processing (decision making)
Motor Output (response)
Motor Function
- Nerve impulses (CNS) are conducted along motor neurons to effectors
- Effectors - Muscles or glands that respond to decisions made in CNS
Integrative Function
- Coordination of sensory information to CNS
- Processing of info is basis of decision-making
Sensory Function
- Provided by sensory receptors
- Info travels from receptors to sensory neurons, that transport to CNS
Bipolar Neurons
Structure: 2 processes extending from soma, a dendrite+axon
Ulipolar Neurons
Structure: Have one process extending from soma and splits into 2
peripheral process has dendrites near a peripheral body and central process runs into the CNS
Multipolar Neurons
Structure: Many dendrites but one axon rising form their soma
Parts
Function
Sympathetic Division - Active of conditions of emergency or stress (fight or flight)
Parasympathetic Division - Active in normal restful conditions (Rest and digest)
The two divisions of the ANS exert opposing effects on target organs
Spinal Cord
Begins at the base of the brain
Cervical Enlargement
Thickened area near the top of the spinal cord
Provides nerves to upper limbs
Lumbar Enlargement - A thickened region near the bottom of the spinal cord
Gives rise to the nerves that serve the lower limbs
Luanda Equina
Horse's tail that forms where the spinal cord points inferiority
Consists of spinal nerves in the lumbar and sacral regions
Ascending Tracts - carry sensory info to the brain
Descending Tracts - Carry motor info from brain to muscles and glands (effectors)
Transmit impulses to and from the brain and house spinal reflexes
Spinal Reflexes - Controlled by reflex arcs that pass through the spinal cord
Brichial Plaxus (C5-T1) - arise from lower cervical and upper thoracic nerves, supply muscles of skin of arms, forearms.
Lumbosacreal Plexus (L1-S5) - Supply muscle and skin of the lower area
Cervical Plexus (C1 -C4) - lie on either side of the neck, supply muscles and skin of neck, and also control the diaphragm
Nerve Impulse
Continuous Conduction
Occurs in unmylinated axons
Conduct impulses subsequently over entire length of their membrane
Salatory Conduction
Occurs in myelinated axons
The myelin sheath insluated axons
Impulses "jump" from one node of ranvier to another
Action Potential
Upon reaching threshold potential there is a change to +30Mv, and through all-or-nothing respose
2) Synaptic knob membrane becomes more permeable to calcium ion, and htey diffuse inward
3) In the presence of calcium ions, synaptic vesicles fuse to synaptic knob membrane
4) Synaptic vesicles release their neurotransmitters into synaptic cleft