Nervous System by Claude Magno N1G Flashcards
what is the master controlling and communicating system of the body?
the nervous system
what are the functions of the nervous system?
- sensory input
- integration
- control of muscles and glands
- homeostasis
- center for mental activities
what are the divisions of the nervous system?
central nervous system (CNS) and peripheral nervous system (PNS)
what is the function of the CNS?
processes, integrates, stores, and responds to information from the PNS
what are the organs of CNS
brain and spinal cord
what is the function of the peripheral nervous system?
- detects stimuli and sends it to the CNS
- the PNS with receive and transmit the information to the affected area after the CNS processes the information
what are the organs/structures of the PNS?
nervous tissue outside of the CNS, sensory receptors, and nerves
what are the divisions of the peripheral nervous system?
- sensory division
- motor division
what is the function of the sensory division?
transmits action potentials from sensory receptors to the CNS
what is the function of the motor division?
carries action potentials away from CNS in cranial or spinal nerves
what are the 2 subdivisions of the motor division?
somatic nervous system and autonomic nervous system
what is the function of the somatic nervous system?
innervates skeletal muscles
what is the function of the autonomic nervous system?
innervates cardiac muscle, smooth muscle, and glands
does the autonomic nervous system have subdivisions?
yes, it has 3 subdivisions namely sympathetic, parasympathetic, and enteric
what is the sympathetic nervous system?
active during physical activity
what is the parasympathetic nervous system?
regulates resting functions
what is the enteric nervous system?
controls digestive system
what are neurons?
excitable cells that transmit electrical signals, receive stimuli, and transmit action potentials
what are the 3 components of neurons?
cell body (stroma), dendrites, axon
what is the cell body/soma?
contains the nucleus and a nucleolus, as well as the golgi apparatus, mitochondria, and other organelles
what are axons?
cytoplasmic extension of the cell body that transmits action potentials to other cells
what are dendrites?
short, branched cytoplasmic extensions of the cell body that usually conduct electrical signals toward the cell body
what are the different types of neurons?
- Multipolar Neurons (Motor) - have several dendrites and a single axon
- Bipolar Neurons - 1 axon and dendrite (components of sensory organs)
- Unipolar Neurons - have a single axon; most sensory neurons
what are Non-neural Cells (Glial Cells)?
provide a supportive scaffolding for neurons and also segregate and insulate them
what are Astrocytes?
- most abundant, versatile
highly branched - clings to neurons and their synaptic endings
- cover capillaries
- support and brace neurons and blood vessels (anchor neurons to their nutrient supplies)
- influence the functioning of the blood-brain barrier
what are Ependymal Cells?
cells that line the ventricles of the brain and the central canal of the spinal cord and produce cerebrospinal fluid (CSF)
what is Oligodendrocytes?
they form myelin sheaths around the axons of several CNS neurons
what are Schwann cells?
cells that form myelin sheaths around the part of the axon of the PNS neuron
what is a Myelinated axon?
an axon with a myelin sheath (whitish, fatty (protein-lipid), segmented sheath around most long axons) produced by oligodendrocytes or schwann cells
what is the function of a myelin sheath?
it increases the speed of nerve impulse transmission and protects the axon
what is the rode of ranvier?
it is the gaps in the myelin sheath
what is the difference of the white matter from gray matter?
white matter consists of myelinated axons that propagate action potentials
and forms nerve tracts in the CNS and nerves in the PNS
gray matter is collections of neuron cell bodies or unmyelinated axons that forms cortex and nuclei in the CNS and ganglia in the PNS
what is the Concentration Differences Across the Plasma Membrane
Na+, Ca^2+, and Cl- ions are greater outside the cell than inside while K+ ions and negatively charged molecules are greater inside
what is Resting Membrane Potential (RMP)?
the charge difference across the plasma membrane when the cell is not being stimulated (the inside of the cell is negatively charged compared with the outside cell)
what is Depolarization?
decrease in K+ concentration gradient and increase in Na+ and Ca^2+ membrane permeability making the charge of the inside of the cell more positive
what is Hyperpolarization?
increase in K+ concentration gradient and decrease in Na+ and Ca^2+ membrane permeability making the charge of the inside of the cell more negative
what are the phases of action potentials?
- Depolarization Phase
- Repolarization Phase
- Afterpotential
what is Absolute Refractory Period?
time during an action potential when a stimulus cannot initiate another action potential
what is Relative Refractory Period?
time during which a stimulus is stronger than threshold can evoke another action potential
what is Action Potential Frequency?
it is the number of action potentials produced per unit time in response to stimuli
what are Synapses?
junction between 2 cells where communication takes place
what is a Presynaptic Cell?
it transmits signal towards a synapse
what is a Postsynaptic Cell?
it receives the signal after it crossed a synapse
what are the Types of Synapses?
- Electrical Synapse
- Chemical Synapse
what is an Electrical Synapse?
gap junctions in which tubular proteins called connexons allow ionic currents to move between cells and is common in cardiac muscles and other muscles with coordinated contractions
what is a Chemical Synapse?
type of synapse which uses neurotransmitters released in the synaptic cleft to convert signal from presynaptic neuron to postsynaptic neuron
what are the components of a chemical synapse?
- presynaptic terminals
2.postsynaptic terminals - synaptic cleft
what is a presynaptic inhibition?
decreases neurotransmitter release
what is Presynaptic Facilitation?
increases neurotransmitter release
what is Excitatory Postsynaptic Potential (EPSP)?
depolarizing graded potential of the postsynaptic membrane
what is Inhibitory Postsynaptic Potential?
hyperpolarizing graded potential of the postsynaptic membrane
what is Spatial Summation?
occurs when 2 or more presynaptic terminals simultaneously stimulate a postsynaptic neuron
what is Temporal Summation?
occurs when 2 or more action potentials arrive in succession at a single presynaptic terminal
what is Convergent Pathways?
many neurons synapsing with few neurons and have collateral branches of postsynaptic neurons synapsing with presynaptic neurons
what is Divergent Pathways?
few neurons synapsing with many neurons
what is a Junction?
junction between two cells where communication takes place
what is the difference between somatic and autonomic nervous system?
somatic: controlled consciously; axons extend to skeletal muscles and have and excitatory effects
autonomic: controlled unconsciously; found in smooth muscle, cardiac muscles, and glands
what is Sympathetic division?
it controls body’s “fight or flight” response; preganglionic cells bodies are in lateral horns of the spinal cord gray matter from T1 to L2 and pass through ventral roots to white rami communicates to sympathetic chain ganglia
what is Parasympathetic division?
controls the body’s response to rest; preganglionic cell bodies are in nuclei in brainstem or lateral parts of spinal cord gray matter from S2 to S4 and pass to the ganglia through cranial nerves
what is the Enteric Nervous System?
consists of nerve plexuses in the wall of the digestive tract
what is the Neurotransmitters of the ANS?
- Acetylcholine
- Norepinephrine (epinephrine)
what releases Acetylcholine?
- cholinergic neurons
- all preganglionic neurons
- all parasympathetic postganglionic
- some sympathetic postganglionic
what released Norepinephrine?
- adrenergic neurons
- most sympathetic postganglionic neurons
what does Norepinephrine bind to?
Alpha and beta receptors
found in most sympathetic effector organs
what does Acetylcholine bind to?
Nicotinic receptor (found in all postganglionic neurons
excitatory) and Muscarinic receptors (found in all parasympathetic effector organs)
what can Autonomic reflex activity be influenced by?
hypothalamus and higher brain center
what can Sympathetic and parasympathetic division influence?
activities of the enteric nervous system through autonomic reflexes
Does the Enteric nervous system function independently or dependently?
Enteric nervous system can function independently of the CNS through local reflexes