L6- Test 2 Flashcards
What is the function of the nervous system?
To control/ coordinate body functions
What is the nervous systems goal?
To maintain homeostasis
The functional unit of the nervous system are ________
Neurons
What are the 2 types of signals?
Chemical and electrical
Electrical signaling
Happens in a neuron
Chemical signals
Happen between 2 neurons
Central (CNS) nervous system
Brain and spinal cord
Peripheral (PNS) nervous system
Nerves and ganglia
Tracts (CNS)
Bundle of neuron axons
Nuclei (CNS)
Cluster of neuron cell bodies
Nerve (PNS)
Bundle of neuron axons
Ganglia (PNS)
Cluster of neuron cell bodies
What are axon collaterals?
Branching of axon - allowing communication w/ many neurons
What are the 3 structural classifications of neurons?
- unipolar, multipolar, bipolar
Structural classifications of neurons are based on ________ of cell bodies
Polarity
What are the 3 functional classifications of neurons?
Sensory, interneuron, motor neuron
Interneurons are found where and tend to be what structural cell?
Completely in cell ; multipolar
Motor neuron somatic found where
In skeletal muscle; multipolar
Motor neuron are found where
Cardiac muscle, smooth muscle, and glands ; multipolar
What do sensory neurons do?
They sense the environment
What do interneurons do?
They integrate sensory input and initiates motor output
What do motor neurons do?
They carry out the signal from the interneuron
Synapses
Junction/ communication b/w 2 cells
What are the two types of neural pathways and how are they different?
Simple - processing by 1 interneuron
Complex - processing by a chain of interneurons
Afferent
Arrive (sensory)
Efferent
Exit/ motor
Reflex arc includes….
- Receptor
- Sensory neuron
- Interneuron
- Motor neuron
- Effector
The 2 cell types of the nervous system include _________ and ___________
Neurons - conduct electrical signals
& neuroglial cells - doesn’t conduct electrical signals
Astrocytes form…..
The blood brain barrier in CNS
Schwann cells form….
Myelin in PNS
Oligodendrocytes form….
Myelin in CNS
Communication of a neuron
- Cell body/ dendrites - integrate physical/ chemical input
- Axon - conduct electrical signals
- Axon terminals - release neurotransmitters
How do neurons create electrical signals of communication?
Changes in membrane potential
How do neurons communicate with each other ➡️ create neural pathways
Neurotransmitters bind to receptors in synapse
Membrane potential
The voltage difference across a membrane
What cause the -70mv resting membrane potential?
- the Na+/K+ pump ; 3 Na+ out and 2 k+ in
- more k+ leak channels than Na+ channels
- having large negatively charged proteins stuck inside cell
Depolarization
Membrane becomes less polar
- na+ voltage gated channel opens
Repolarization
Membrane returns to the resting membrane potential
Hyperpolarization
Membrane becomes more polar
- k+ continue moving out while ca+ channel closed
REFRACTORY PERIOD
Threshold potential
Change in membrane potential required to generate an action potential
Action potential (Ap)
Temporary and transient all or none change in RMP
Graded potential (Gp)
Small change in membrane potential (hyperpolarizing/ depolarizing)
Generation of action potentials occur at
Cell bodies
- needs to get at threshold potential in order to release action potential
Initial segment is found at _________
The beginning of axon
Excitatory postsynaptic potential (Epsp)
Moves resting membrane potential closer to threshold potential
Inhibitory post synaptic potential (Ipsp)
Moves resting membrane potential further from threshold potential
What causes change in resting membrane potential?
Regulated opening/closing of specific gated ion channels
➡️ voltage gated ion channels
What ions are responsible for action potentials during depolarization? Repolarization? Hyperpolarization?
Depolarization — voltage gated Na+ channels open ( initiated by graded potentials)
Repolarization — voltage gated k+ channels open (initiated by depolarization)
Hyperpolarization — k+ continues to move out (producing refractory period)
Significance of refractory period (RP)
- Ensures each action potential is an individual event
- Prevents action potentials from moving backwards in an axon
What are the two types of refractory periods?
Absolute refractory period — voltage gated Na+ channels = inactive/ can’t open
Relative resting potential— voltage gated Na+ channels = closed but can open w/ strong stimulus
Myelinated vs unmyelinated axons (AP propagation)
Unmyelinated — cycle based ➡️ depolarization, Repolarization, resting membrane
myelinated — faster ; contain node of ranvier w/ voltage gated na+ channels
Action potential
Propagation speed down neurons axon
What factors increase an action potentials propagation speed?
Myelin ( saltatory conduction) & larger axon diameter
Slow neurons vs fast neurons
Slow - thin unmyelinated fibers
Fast - think myelinated fibers
How is a week signal distinguished from an intense signal?
The intensity of stimulus depends on the frequency
By increasing stimulus frequency it ________ action potential frequency
Increases
Decreasing stimulus frequency it _________ action potential frequency
Decreases
What is the difference between a single action potential and a propagation of action potentials?
Action potential = all or none event that happens once and takes place on small part of axons membrane (not traveling down)
Propagation = one action potential initiates (through influx of na+) a depolarization in adjacent downstream axon membrane creating an Ap ➡️….. NERVE SIGNAL
What is the nerve signal that reaches your brain?
Action potentials
