Nervous System Flashcards
What are the two main anatomical divisions of the nervous system?
The central nervous system (CNS) and the peripheral nervous system (PNS)
What makes up the CNS?
The brain and spinal cord
What do the brain and spinal cord contain?
Neural tissue, connective tissues, and blood vessels
What are the two main functions of the CNS?
Processing and coordinating
What are the three things the CNS processes and coordinates?
It processes and coordinates: sensory data from both inside and outside the body, motor commands that control the activities of peripheral organs (like skeletal muscle), and higher functions of the brain like intelligence, memory, learning, and emotion.
What makes up the PNS?
All neural tissue outside of the brain and spinal cord
What are some structures of the PNS?
Sensors, motor neurons, and nerves
What are the functions of the PNS?
Deliver sensory info to the CNS and carry motor commands to peripheral tissue + systems
What’s the difference between afferent and efferent?
Afferent is to CNS, efferent is from CNS
What does the afferent division do?
It carries sensory info form the PNS sensory receptors to the CNS. Receptors
What does the efferent division do?
It carries motor commands from the CNS to the PNS to the effectors (muscles and glands). Effectors
What are the two divisions of the PNS?
The somatic nervous system (SNS) and the automatic nervous system (ANS)
What are the two divisions of the ANS?
The sympathetic division and the parasympathetic division
What does the SNS do?
It controls skeletal muscle contractions/ voluntary contractions
What does the ANS do?
It controls subconscious contractions/ contractions of smooth and cardiac muscle
What is the effect of the sympathetic division?
It has a stimulating effect
What is the effect of the parasympathetic division?
It has a relaxing effect
What are the two types of neural tissues?
Neurons and neuroglia
What are neurons?
They’re neural tissues that send and receive signals and and are the basic functional units of the nervous system
What are neuroglia?
They’re neural tissues that support and protect neurons
Where are neurons commonly found?
In the central nervous system (CNS)
What do neurons look like?
They have a cell body, short branched dendrites, and a long single axon
What are makes up neural tissue cells and neurons?
They have a large nucleus and nucleolus, cytoplasm, mitochondria, RER and ribosomes that make up the nissl bodies, and a cytoskeleton
What don’t neural tissue cells and neurons have?
They don’t have centrioles
What do nissl bodies do?
They produce neurotransmitters
What is a characteristic of dendrites?
They’re highly branched
What do dendrites make up?
Dendrites make up 80-90% of neuron surface area
What do dendrites do?
They receive information from other neurons
What is a characteristic of axons?
They’re long
What do axons do?
They carry electrical signals (action potentials) to the target
What different parts do axons have?
They have axon hillocks, collaterals, and synaptic terminals
What is an axon hillock?
It’s a thick section of an axon cell’s body and it attaches to the initial segment
What is a collateral?
The branches of a single axon
What are synaptic terminals?
They’re the tips of an axon, and are also known as axon terminals
What is a characteristic of bipolar neurons?
They’re small
What makes up a bipolar neuron?
One dendrite and one axon
Where are bipolar neurons found?
They’re found in special sensory organs
What are very long axons?
Unipolar neurons
What are unipolar neurons?
Very long axons
What are unipolar neurons fused to?
Dendrites and an axon
What’s a characteristic of unipolar neurons?
The cell body is to one side
Where are unipolar neurons found?
In sensory parts of the PNS
What’s a characteristic of multipolar neurons?
They have multiple dendrites and one axon
Where are multipolar neurons commonly found?
In the CNS, and it includes all skeletal muscle motor neurons
What are the three functional classifications of neurons?
Sensory neurons, motor neurons, and interneurons
What are sensory neurons?
Afferent neurons of the PNS
What are motor neurons?
Efferent neurons of the PNS
What are interneurons?
Association neurons
What are cells that support and protect neurons?
Neuroglia
What are cells that send and receive signals?
Neurons
What are the basic functional units of the nervous system?
Neurons
What carries electrical signals to the target?
Axons
What part of the axon attaches to the initial segment?
The axon hillock
What are branches of a single axon called?
Collaterals
What are the tips of an axon called?
Synaptic terminals
What type of neurons are afferent neurons of the PNS?
Sensory neurons
What are efferent neurons of the PNS called?
Motor neurons
What are association neurons called?
Interneurons
What is the area where a neuron communicates with another cell called?
A synapse
What is a synapse?
The place where a neuron communicates with another cell
What is a presynaptic cell/neuron?
The neuron that sends the message
What is a postsynaptic cell?
The cell that receives the message
What is the synaptic cleft?
The small gap that separates the presynaptic and postsynaptic membranes
What is the small gap that separates the presynaptic and postsynaptic membranes called?
The synaptic cleft
What are neurotransmitters?
Chemical messengers
Where are neurotransmitters released?
At the presynaptic membrane
What do neurotransmitters affect?
They affect the receptors of the postsynaptic membrane
What breaks down neurotransmitters?
Enzymes break down neurotransmitters and recycle them
What makes up nearly half the volume of the nervous system?
The neuroglia
What are the different types of neuroglia in the CNS?
Ependymal cells, astrocytes, microglia, and ogliodendrocytes
What are the different types of neuroglia in the PNS?
Satellite cells and Schwann cells
What forms the epithelium called the ependema?
Ependymal cells
What do ependymal cells form?
The epithelium called the ependyma
What do ependymal cells line?
They line the central canal of the spinal cord and the ventricles of the brain
What do ependymal cells secrete?
They secrete cerebrospinal fluid (CSF)
What secretes cerebrospinal fluid?
Ependymal cells
What do ependymal cells have?
They have cilia or microvilli that circulate the CSF
What do ependymal cells monitor?
The CSF (cerebrospinal fluid)
What do ependymal cells/ the ependyma contain?
They contain stem cells for repair
What do astrocytes maintain?
They maintain the blood-brain barrier
What do astrocytes repair?
They repair damaged neural tissue
What do astrocytes guide?
They guide neuron development
What are astrocytes called in the PNS?
Satellite cells
What do astrocytes do?
They maintain the blood-brain barrier, they repair damaged neural tissue, and they guide neuron development
Where do microglia migrate?
Through neural tissue
What migrates through neural tissue?
Microglia
What do microglia do?
They clean up cellular waste, debris, and pathogens
What cleans up cellular waste, debris, and pathogens?
Microglia
What do ogliodendrocytes do?
They wrap around axons to form a myelin sheath
What does the myelin sheath do?
It increases the speed of action potentials and makes nerves appear white
What do Schwann cells form?
They form the myelin sheath around peripheral axons
What makes up the myelin sheath around peripheral axons?
Schwann cells
What are internodes?
Myelinated segments of the axon
What are the myelinated segments of the axon called?
Internodes
What are nodes also called?
The Nodes of Ranvier
What are the nodes of ranvier?
The exposed parts of axons
Where may axons branch?
At the nodes of ranvier
What may happen at the nodes of ranvier?
The axons may branch
What is the electrochemical gradient?
The sum of chemical and electrical forces acting on the ion across the cell membrane
What is the electrochemical gradient a form of?
It’s a form of potential energy
What is an example of a form of potential energy?
The electrochemical gradient
What are some examples of ions that have electrochemical gradients?
Na+ and K+
What are the two different types of ion channels?
Passive and active
What type of ion channels is leaky and always open?
Passive
What are some characteristics of passive ion channels?
They’re leaky and always open, and their permeability changes with conditions
What are some characteristics of active ion channels?
They’re gated channels and open/ close in response to stimuli
What are gated channels also called?
Active ion channels
What are the three types of active channels?
Chemical, voltage, and mechanical
When do chemically gated channels open?
When they’re bound to chemicals
Where are chemically gated channels found?
On the neuron cell body and dendrites
What makes voltage gated channels open?
With electricity
Where are voltage gated channels found?
They’re found in the axons, sarcolemma, and the heart
What makes mechanically gated channels open?
They respond to membrane distortion
Where are mechanically gated channels found?
They’re found in sensory receptors
What are graded potentials?
Changes in transmembrane potential that can’t spread far from the site of stimulation
What are changes in transmembrane potential called?
Graded potentials
What produces a graded potential?
Any stimulus that opens a graded channel
What happens when the stimulus is removed?
The transmembrane potential returns to normal
What is step 1 of a graded potential?
The resting membrane is exposed to a chemical, and the sodium ion channel opens. Sodium ions enter true cell, and transmembrane potential rises, causing depolarization
What is step 2 of a graded potential?
The movement of Na+ ions through the channel produces a local current, which depolarizes the nearby cell membrane (graded potential).
What is proportional to the change in potential?
The stimulus is proportional to the change in potential
What powers the sodium potassium pump?
ATP
What exchanges 3Na+ for 2K+?
The sodium potassium pump
What does the sodium potassium pump exchange?
It exchanges 3Na+ for 2K+
What does the sodium potassium pump do (as a whole)?
It maintains and restores the resting potential of -70mV
What does hyperpolarization do?
It increases the negativity of the resting potential
What results in hyperpolarizartion?
The opening of a potassium channel results in hyperpolarization
During hyperpolarization, what happens to the positive ions?
The positive ions move out, not into the cell
What is the opposite effect of opening a sodium channel?
Hyperpolarization
The opening of what channel has the opposite effect of opening a sodium channel?
The opening of a potassium channel creates the opposite effect of opening a sodium channel
