Nervous System Anatomy & Physiology Flashcards
What two major structures make up the CNS?
brain and spinal cord
What one type of structure makes up the PNS?
All the nerves that connect the rest of your body to the brain and spinal cord
3 main structural divisions of the brain
Cerebrum, cerebellum, brainstem
Major functions of the cerebrum
Responsible for higher-level functions like thought and memory, and complex processing of sensory and motor information
Major functions of the cerebellum
Regulates motor control
Major functions of the brainstem
Controls many vital functions (e.g. cardiac and respiratory)
Gray matter
Made up of neuron cell bodies (dorsal and ventral horns)
White matter
Made up of myelinated axons
Tracts
Groups of axons running up and down the spinal cord
Ascending tracts
carry sensory information from the body (skin, muscles, organs, etc) to the brain (AFFERENT PATHWAYS)
Descending tracts
carry motor signals from the brain to the body (EFFERENT PATHWAYS)
What tough membrane protects the brain and spinal cord?
Meninges
What tough membrane protects the nerves?
Epineurium, perineurium and endoneurium
What are the two main functions of CSF?
- Provides cushioning and support
- Clears waste out of the CNS
What are the two main divisions of the PNS?
Somatic and autonomic
Major functions of the somatic sensory system?
Collects information about pressure, temperature, proprioception and pain
Major functions of the somatic motor system
Controls all of the voluntary muscle movements in the body
Somatic nervous system
Nerves that innervate skin, joints and voluntary muscles
Autonomic nervous system
The nerves that control involuntary functions (e.g. blood pressure, intestinal function, gland secretions); consists of sensory and motor elements
What are the major 2 categories of cells in the nervous system?
Neurons and glial cells
Function of neurons
They process and transmit information electrochemically
Functions of glial cells
Considered support cells
4 structural elements that make neuronal cells different from most non-nervous system cells (by allowing directional flow of information)
- Dendrites (receive information)
- Axons (sends information)
- Specialized cell membrane that allows them to be electrically excitable
- Synaptic terminals (release neurotransmitters)
Name 4 types of glial cells
- Astrocytes
- Myelinating cells
- Microglia
- Ependymal cells
Functions of astrocytes
Regulation of chemical content of the CNS extracellular space (by taking up or releasing ions, nutrients, neurotransmitters, etc. as needed)
2 types of myelinating cells and where they’re found
Oligodendrocytes (in the CNS)
Schwann cells (in the PNS)
Functions of Myelinating cells
Wrap around neuron axons in many layers, providing electrical insulation
Which two types of cells make white matter white?
Schwann cells and oligodendrocytes
Functions of microglia
The brain’s main form of immune defense; dispose of damaged neurons, infectious agents and other debris in the CNS; shape changes based on location and current level of activity
Functions of ependymal cells
- Line the fluid-filled cavities of the brain (ventricles) and spinal cord (central canal)
- Produce and reabsorb CSF and move it around by beating their cilia
- Makes up choroid plexus, a structure that produces most of the CSF in the body
Define resting membrane potential and if negative or positively charged
- The charge inside of a neuron at rest
- Negatively charge (-70mV)
Inhibitory synapse
Synapses where the neurotransmitter binding to the receptor causes postsynaptic cell to become more negative
Excitatory synapse
Synapses where the neurotransmitter binding to the receptor causes postsynaptic cell to become more positive
What type of ion flow is responsible for bringing the membrane potential from the threshold value to a positive value?
When the membrane potential reaches -55mV, voltage-gated sodium ion channels open, allowing sodium ions to flow into the cell
What happens at the action potential peak?
Voltage-gated sodium channels close, and voltage gated potassium ions open (allowing potassium to flow out of the cell)
What happens once an action potential reaches the synaptic terminal?
Voltage-gated calcium channels open, allowing calcium ions to flow in which causes neurotransmitters to be released into the synaptic cleft
Two main functions of myelin sheaths
electrically insulates and increases the speed of the action potential
Saltatory conduction
Action potential jumps from node to node since no voltage-gated channels live under the myelin sheaths; makes the AP faster
