Coordination and Regulation- Nervous Systems Flashcards
3 General Roles of Nervous System
- collects info from internal or external environment using sensory neurons
- Process and integrate info- evaluates based on past experiance or genetics
- Transmits info- coordinates/ regulates effector organ/ cells
What are Neurons
Generate bioelectric signals which are used to transmit info to other cells
What are Glia
“support cells””- assist neuronal signalling, produce cerebrospinal fluid, maintain environment around neurons
Neuron
individual cells
nerve
a bundle of axons
axons
nerve fiber
synapses
connection between axon terminal and effector cell
effector
can be a neuron, muscle cell, any other cell
bioelectricity
happens all around membrane
potential
difference in electrical charged between regions- measured in volts or millivolts
current
flow of electrical charge between regions- opposites attract, likes repel
membrane potential
unequal charge distribution across a cell membrane
electrical potentials
used to initiate an AP in axon hillock and used to conduct AP along axon -current (ions) travel along surface of membrane, small, can depolarize or hyperpolarize, can only travel short distance
Depolarization
more +ve inside of cell, makes cell less negative
Hyperpolarization
more -ve inside cell, makes cell more negative
Resting Membrane Potential
measured when neuron is inactive -about -70mV in neurons and muscle cells
Electrotonic Potential
passive change in membrane potential -amplitude decreases with distance from point of initiation
Action Potential
initiated at axon hillock region, are all or nothing but short
Unmyelinated axon
reduce threshold at axon hillock, concentration of Na+v channels and spreads along membrane toward terminals
-axon diameter determines speed of conduction (large=faster)
Myelinated axon
surrounded by myelin insulation preventing ions from crossing membrane
Electrical Synapses
gap junctions directly connect to cytoplasm of each cell, ions flow between cells, rapid flow of current
Chemical Synapses
pre and postsynaptic neurons seperated by synaptic cells
Main difference between chemical synapse and electrical synapse
neurotransmitter binds to postsynaptic receptors, channels open, depolarization (excitatory) or hyperpolarization (inhibitory)
Neurotransmitters
stimulates skeletal muscle contraction
Ionotropic Receptors
ligand gated ion channels, post synaptic response depends on ion current
Na+ channels are depolarized by what
acetylcholine
Cl- channel is
hyperpolarized by GABA
Sponges
no neurons but still have basic cell physiology
Ganglia
collections of neuronal cell bodies= sites of integration
Cephalization
concentration of neurons/ ganglia in a “head” or region
Somatic
voluntary control, drives skeletal muscle
Autonomic
involuntary control, helps coordinate includes sympathetic and parasympathetic
Parasympathetic
organ specific, “rest and digest”, activity targets organs, controls smooth muscles and different glands
Preganglionic Neurons
-in CNS -brainstem or spinal cord
-myelinated axons
-transmit signals from CNS to autonomic ganglia (ganglia outside CNS)
Postganglionic Neurons
-neurons located in autonomic ganglia (outside CNS) and part of PNS
-unmyelinated axons
-transmit signals from autonomic ganglia to target organs -smooth, cardiac muscle or glands
Neurotransmitter
-chemical messenger released by neurons that can transmit signals across synapses to target cells
-classified into; acetylcholine, norepinephrine, dopamine, serotonin, etc
-excitatory or inhibitory effects on target cell, depending on type of cell
Receptors
-protein molecule located on surface of or within target cell that can bind specifically to a neurotransmitter or hormone
-mediate biological effects of neurotransmitters or hormones by initiating intracellular signaling pathways when activated by the binding of a neurotransmitter or hormone
-classified by structure, function, and type of signaling molecule they bind to
