Nervous System Flashcards
What is an interneuron
Circuit neuron of the CNS that relays information between afferent (sensory) and efferent (motor) neurons
Differentiate somatic system and autonomic system
BOTH are subdivisions of efferent system composed of efferent neurons
Somatic: communicates with skeletal muscles, voluntary
Autonomic: communicates with smooth muscle and glands, involuntary
Sympathetic vs parasympathetic division
Sympathetic: increases energy consumption and prepares body for action
Parasympathetic: stimulates body activities that squire and conserve energy
List the stages of the neural circuit
Receptor Afferent neuron Interneuron Efferent neuron Effector
Describe what happens when you touch something hot
Pain receptors in finger tips stimulate an afferent neuron
The afferent neuron transmits the impulse to the spinal chord
Interneurons integrate the information
One efferent neuron stimulates flexor muscles to contract, another EN sends signal that keeps extensor muscle from contracting
Hand is pulled away
Nervous system is divided into what 2 parts?
Central nervous system: brain, spinal chord
Peripheral nervous system:
Nervous, gangli
Includes 31 pairs of spinal nerves, 12 pairs of cranial nerves
Includes somatic nervous system and autonomic nervous system
What are the 3 basic functions of the nervous system?
SENSORY - gather info about changes within body. Send nerve impulses to CNS
INTEGRATIVE - information “brought together” and interpreted (memory, thoughts, decision making) (association neuron or interneuron)
MOTOR - responses to impulses to maintain homeostasis ex shivering
What are the 2 major portions of a neuron and their function?
DENDRITES - receptor. Along with cell body they form receptive surfaces of neurons
AXON - conducts impulses away from cell body, sometimes branched (collaterals) and end has many branches
What are the 5 types of neuroglial cells?
Microglial cells Oligodendrocytes Astrocytes Ependymal cells Schwann cells
Microglial cells
Scattered throughout, digest debris or bacteria
Oligodendrocytes
Provide insulation around axons in CNS (only brain and spinal chord)
Astrocytes
Connect blood vessels to neurons important cause neurons need oxygen to carry messages
Ependymal cells
Form a membrane that covers certain cavities in the brain
Shwann cells
Form insulation
What are myelin sheaths for?
Necessary for insulation of neuron
What’s the difference between oligodendrocytes and shwann cells?
Olig- only in CNS
Shwann- peripheral, make up myosin sheaths
Myelin
Insulation surrounding axons
Nodes of ranvier
Gaps in the insulation, where signals jump
Differentiate white matter and grey matter
White matter - myelinated axons (protected)
Grey matter - Unmyelinated axons (no protections)
What is nerve impulse
- series of action potentials along nerve fibre
- very weak electric current
Differentiate afferent and efferent neuron
Afferent: carries impulses from sensory receptors TOWARDS central nervous system
Efferent: caddies impulses FROM central nervous system to skeletal muscles (motor neuron)
Describe resting potential
- inside of a neurons membrane has a negative charge
- sodium and potassium use energy from ATP to pump sodium out of the cell and potassium into the cell
- the inside of the membrane builds up a net negative charge relative to the outside called a membrane potential
- if electrodes placed across the cell membrane the resting membrane potential is -70mv
- this difference in charge means the membrane is polarized (unequal distribution of charges)
How does a sodium -potassium pump work?
- for every 3 Na+ out, 2 K+ come in
- uses ATP (splits into ADP and inorganic phosphate) to alter pump shape
Describe the action potential process
- Neuron membrane maintains resting potential (-70mv)
- Threshold stimulus is received (hitting hand)
- Voltage hated Na+ channels open
- **Na+ ions diffuse inwards, depolarization (+40mv) inside of membrane is now positive
- Na+ channels close, K+ channels open
- K+ ions diffuse outwards, repolarizing the membrane (trying to make it negative again)
- Membrane becomes hyper polarized (passes resting potential point) to -90mv
- K+ channels close
- Na/K pump restores resting potential by calmly working
- During refractory period, membrane cannot go through another action potential. Entire process continues along length of axon until it reaches the end
