Human Phys Exam 3 Flashcards
what is the central nervous system composed of?
brain, spinal cord
what are the pathways within the peripheral nervous system
afferent and efferent pathways
difference betweeen afferent and efferent pathways?
afferent: go toward CNS
efferent: send info from CNS
what are the two systems within the efferent pathways?
autonomic and somatic nervous system
difference between autonomic and somatic nervous systems?
autonomic: symathetic (excitatory) division, paraympathetic (inhibiotry) division
somatic: stimulates skeletal muscle contraction
what are afferent neurons
originiate in the periphery of the body via a sesory or visceral receptor and travel toward CNS
what are efferent neurons
originate in CNS and travel to periphery to produce an effect in the body (efferent neurons towards effector organ)
what are interneurons
found in CNS, allow communication btw afferent and efferent neurons
what are excitable cells
cell that can produce electrical signals
what are action potentials
electrical signals produced by excictable cells
what are neurons
excitable cells in the nervous system
what are glial cells
structural cells found in the nervous system, pack and keep cells together (90% of cells)
what is the basic structure of a neruon?
cell body, dendrites, axon, axon terminal
what is myelination? effect?
- due to Schwann cells wrapping around axon, creates myelin sheath that acts as insulation
- myelination increases conduction velocity of nerve impulse
what is the membrane potential?
electrical potential difference are created in excitable cells by separating oppositely charged ions
what is the resting membrane potiental
-70mv
how does depolarization occur?
when an excitable cells membrane permeability is altered, the membrane potiental changes
-spread of depolarization is called an action potential
what is the resting membrane potential crated from?
K+ leaking out of the cell faster than Na+ leak into the cell (3 Na pumped out, 2K pumped in)
depolarization refers to?
a change in the membrane potiental from its resting negative value to a more positive value
where are gated ion channels found?
dendrites, cell body, axon hilock region of a neuron
what activates gated ion channels?
volatage changes, ligand/recetpor interactions, mechanical stimulation
what are voltage gated cahnnels?
open with change in voltage in axon hilock, getting shocked, action potentials
what are ligand gated channels?
open due to binding of ligand to membrane recetpor in dendrites, neurotransmitter from another neuron binds to a receptor
what are mechanically gated channels?
open due to mechanical stimuli on dendrite or cell body
-pressure, force
what is hyperpolarization?
if the membrane potiental becomes more negatiave
what is repolarization?
a return to the rsting membrane potiental
what are graded potientals?
small changes in the membrane potential due to ion channels opening or closing following stimulation by another source
when do graded potientails create action potentials?
if they change membrane potential above threshold
if depolarization occurs these are called ______, if hyperpolarzation occurs ______
excitatory graded potentials, inhibitory graded potentials
the graded potential sends a stiumulus to the axon hillock but it has to be strong enough so the axon hillock can reach a threshold at ___
-55mv
what are the phases of an action potential?
depolarization, repolarization, after hyperpolarization
what is the all or none principle
if membrane potential goes above threshold an action potential is produced that is always the same magnitude
can a stimulues generate a second action potnetial during the absolute refractory period
no
what is the refractory period
when the membrane is less excitable than at rest
explain action potentials in unmyelinated axons
- action potential propagates down an axon
- pos charges move from the area that has been depolarized to the adhacent area on the membrane
- current flows to adhacent areas based on electronic conduction
do larger or smaller diameter axons have faster conduction velocities?
larger diameter axons
-have less resistance to current flow down axon
how do ions propagate down the axon?
the sites enter a refractory state after it is depolarized
explain action potentials in myelinated axons
- saltatory conduction is used to propagate action potentials
- action potentials cannot be produced ina reas where myelin is present so the current flows from node to node very quickly
- fastest conduction velocities are found in large diameter myelinated axons
what happens at the synaptic transmission?
the action potential reaches the axon terminal which stimulates vesicular movement to terminal membrane by opening Ca channels
-neurotransmitter diffuses to postsynaptic memebrane and binds to receptors
what are excitatory synapses?
bring postsynaptic neurons closer to thershold for AP to occur
-depolarization is called an excitatory postsynaptic potential
what is the difference between a fast and slow excitatory respose?
fast excitatory response is when a neurotransmitter opens ion channels allowing for a rapid depolarization
-slow is when a neurotransmitter activates a Gprotein/2nd messenger cascade that is slower to create a depolarizaiton
what do inhibitory synapses cause?
causes postsynaptic neuron membrane potentials to be hyperpolarized or stabilized
-IPSP
what is convergence summation?
when a number of presynaptic neurons synapse on one postsynaptic neuron
what is temporal summation?
when 2+ postsynaptic potentials are produced in rapid succession at the same synapse and are additive to create a greater depolarization
what is spacial summation
2+ postsynaptic potentials from different synapses overlap are are additive
what are modulatory synapses
regulate communication across another synapse
what are axoxaxonic synapses
form btw axon terminals of 2 diff neurons, modulatory synapses
-neurotransmittor induces a change in the amount of Ca that enters the axon terminal in response to an action potential
what is presynaptic facilitation?
increaes releases of neurotransmitter from the postsynaptic neuron
what is presynaptic inhibition?
decreases release of neurotransmitter form postsynaptic neuron
what are the different classes of neurotransmitters?
choline derivative, biogenic amines, amino acids, neuropeptides, others
what is the choline derivative neurotransmitter?
acetylcholine
- released from neruons in CNS,PNS
- produced from acetyl coA and choline
- binds to cholinergic recpetors
what enzyme coverges acetly coa and choline?
choline acetyl transferase
what are the 2 types of cholinergic receptors
nicotinic and msucarinic
what are nicotinic cholinergic receptors?
Ach binding to nicotinic receptors causes opening of Na and K channels causing EPSP
- found in PNS
- muscle cells, autonomic neurons
what are muscarinic cholinergic receptors?
- metabotropic
- works via 2nd messenger system in postsynaptic cell
- main receptor in CNS and found on effector organs in body to cause an inhibiting effect
what are the neurotransmitter that are biogenic amines?
catecholamines, serotonin, histamine
-all have an amine group and dervied from amino acids
what are catecholamines?
epinephrine, norepinephrine, dopamine
what are the receptors for EPI, NE and dopamine?
epi and ne: adrenergic
dopamine: dopaminergic
what are the 2 main classes of adrenergic receptors
alpha and beta
- epi: high affinity beta2
- ne: alpha and beta1
what 2 enzymes degrade catecholamines?
monoamine oxidase and catechol O methyltransferase
-occurs at synapses
what degradation of catecholamines can be inhibited?
monoamine oxidase can be inhibited, reuptake molecule cannot
where in the CNS is serotonin found?
brainstem
-regulating sleep and emotions
where in the CNS is is histamine found
hypothalmus
what does the monoamise oxidase enzyme do?
breaksdown neurotransmitter after it has been released so it doesnt stay in the stimulus too long and over stimulate the postsynaptic neuron
what is the effect of the monoamine oxidase inhibitor?
use the drug to inhibit the monoamise oxidase enzyme to create a greater effect
whats an example of a reuptake moleucle inhibitor?
SSRI, more serotonin in the synapse so theres a greater response, helps with production of serotonin
what are the amino acid neurotransmitters?
glutamate, aspartate, GABA, glycine
which amino acids are excitatory? inhibitory?
excitatory: glutamate, asparate (more likely to have an action potential in postsynaptic neuron
inhibitory: GABA, glycine
what is an example of when an excitatory aa being used
when you get hot glutamate and aspartate would be realsed to stimulate the hypothalms to tell the sweat glands to sweat
what are neuropeptides?
short chains or AAs that are found in neurons and likely function as neurotransmitters and hormones
what are other chemical substances that function as neurotransmitters?
nitric oxide and ATP
what fluid makes up the central nervous system?
cerebrospinal fluid, similar composition to plasma (IF)
what percent of blood pumped by the heart is recieved to the CNS?
15%, due to high metabolism
what percent of O2 and glucose does the brain consumed?
o2: 20
glucose: 50
what is not produced in the CNS?
glycogen not stored, fatty acids, cant produce energy anaerobically
what is the bloodbrain barrier?
- protects CNS from harmful substances
- o2, glucose and other materials exchange through the capillaries
- formed by tight junctions btw endothelial cells of cerebral capillaires
why is gluclose and proteins less in CSF compared to plasma?
CSF uses gluclose immediately and lower proteins bc they are restricted from entering the blood within the brain
what are the 3 parts of the brain
forebrain, cerebellum, brain stem
what is the forebrain consist of?
right/left hemispheres
-cerebrum and cerebral cortex
what is the cerebrum
contains the cerebral cortex (surface) and subcortical nuclei (deeper)
what happens in the cerebral cortex?
carries out highest level of neural processing: perceptions, ideas, memory, motor control
-integrating center that recieves and processes sensory info to formulate thoughts and actions
what does the diencephalon contain?
thalamus and hypothalamus
what does the thalamus do?
filters and refines sensory info before it reaches the cerebral cortex, involved in motor movement control
what does the hypothalamus do?
releases tropic hormones to anterior pituitary and controls posterior pituitary hormone release
- produces hunger and thirst and inolved in emotions
- regulates body temp
what does the cerebellum do?
- inferior to the forebrain and posterior to brainstem
- motor coordination balance and procide feedback to produce smooth motor movements
what does the brainstem do and include?
- connects cerebrum and cerebellum to spinal cord
- 3 regions: midbrain, pons, medulla oblongata
what autonomic functions does the brainstem regulate
cardiovascular and respiratory control
what does the brainstem control?
- sleep wake cycles, consciousness, arousal of the cerebral cortex via retiuclar formation
- process cranial nerve info
what are the functional areas of the cerebral cortex?
- primary motor cortex
- premotor cortex
- central sulcus
- primary somatosensory and cortex
- sensory association areas
- visual association areas
- primary visual cortex
- wernickes area
- auditory association areas
- primary aduitory cortex
- limbic association cortex
- olfactory cortex
- brocas area
- prefrontal association areas
what does the limbic system do? different areas?
- collection of areats that function in learning and emotions, controls basic drives
- areas: amygdala, hippocampus, fornix, cingulate gyrus, hypothalamus, thalamus
what processes make up voluntary motor control?
- idea or intention to move
- development of a program of motor commands
- execution of the program of motor commands
- continual feedback to assess and refine the movement
how does the cerebellum help voluntary movements?
functions to correct movements as they occurs, maintain muscle tone, and store info to allow for enhanced coordination of a movement with practice
how are emotions produced?
sensory input and memories
stimuli from both the internal and external environments are detected by
sensory receptots
what are external stimuli detected by?
somatosensory system (skin), proprioceptors(limb position/motion), special sensory ( vision, smell, taste, hearing, balance, equlibrium) system
what are internal stimuli detected by?
visceral receptors that transmit signals to the CNS via visceral afferents
what do receptors in the somatosensory system respond to?
pressure, pain, temp, body position
what do mechanoreceptors respond to?
pressure, force, vibration
what do thermoreceptors respond to?
temperature
waht do nociceptors respond to?
injurious stimuli (pain)
what are modalitiy for mochanoreceptors?
light touch, pressure, vibration, bending of hair, pressure
what are modalities for thermorecptors?
increase in skin temp, decrease in skin temp
what are modalities for nociceptors?
intesne mechanical stimulus, intense hot or cold stimulus, intense mechanical or thermal stimulus, specific chems
what is the difference between fast and slow pain?
fast pain: sharp, pricking, well localized
slow: dull, aching, poorly localized, general
what is visceral pain
detected by nociceptors that are stimulated by tissue damage in internal strucutures
-heart, lungs, live, GI
what is referred pain
result of visceral pain
-occurs due to second order neurons reciving signals from somatic afferents along the visceral afferent
what is the gate control theory of pain
inhibitory interneurons in the spinal cord stimulated by skin mechanorecptors can inhibit the 2nd orderneurons in the spinal cord that transmit pain info (rubbing skin)
what is the endogenous analgesia system
neurotransmitter enkephalin is released from inhibitoy interneurons to inhibit synaptic transmission from the nociceptive afferent to the 2nd order neuron
