Psychology Flashcards
Memorize all people and laws/terms
Anterograde movement
Forward (ex. kinesin)
Retrograde movement
Backwards
Kinesin
Protein
Drives movement of vesicles and organelles along microtubules in axons
Drives anterograde movement (from soma to axon terminus)
Resting Membrane Potential
~-70mV, inside of cell negatively charged and outside of cell positively charged
Membrane proteins required to establish this: Na+/K+ ATPase (with hydrolysis of 1 ATP molecule) and K+ leak channels (allow K+ to flow down gradient out of the cell)
This leaves interior of cell with net negative charge
Cell is polarized (- inside), the becomes depolarized from AP
Change in membrane potential=from movement through ion channels into and out of the neuron=electrochemical impulse
Depolarization
Voltage-gated Na+ channels: open and allow Na+ to flow down gradient and into the cell to depolarize the membrane
Opened from depolarization of membrane from -70mV to threshold potential of -50mV, and then Na+ flow in until reaches ~35mV before inactivating
Once threshold is reached, channels are opened fully, but below threshold they are closed
Depolarization gets passed down the axon with voltage-gated Na+ channels opening when depolarization in neighboring membrane reaches potential (-50mV)
Can AP run out of energy?
NO, it will continue to propagate until it reaches end/synapse
Repolarization
Re-establishes RMP
Voltage-gated Na+ channels inactivate and voltage-gated K+ channels open (but open more slowly than Na+ channels and stay open longer)
VG K+ channels open in response to membrane depolarization
RMP overshoots to ~-90mV and voltage-gated K+ channels close
K+ leak channels and Na+/K+ ATPase continue to function to bring membrane back to resting potential
Schwann Cells
PNS, form myelin (no ions can enter where myelin is present
Oligodendrocytes
CNS, form myelin
Glial Cells
Specialized, non-neuronal cells that typically provide structural and metabolic support to neurons
Maintain a RMP but do not generate APs
Astrocytes
CNS, Guide neuronal development
Regulate synaptic communication via regulation of neurotransmitter levels
Microglia
CNS, remove dead cells and debris
Ependymal Cells
CNS, Produce and circulate CSF
Equilibrium Potential
No net movement
Ex. Na+
-Chemical gradient drives Na+ in and electrochemical gradient drives Na+ out (because inside of cell is too positive)-balance each other at 50mV
-K+ has negative equilibrium potential and driven out by conc. gradient, electrical gradient drives K+ in because inside of cell is too negative and they are attracted, chemical gradient drives K+ out
Equilibrium potential equation
Nernst: E(ion)=RT/zF ln(conc. inside/conc. outside)
- -> Relative concentrations of the ion on each side of the membrane create the chemical gradient
- -> Valence (charge of the ion) creates the electrical gradient
Absolute Refractory period
Na+ channels inactivated (NOT the same as closed)
Can’t be opened again until they return to closed state and membrane reaches resting potential
No AP
Due to inability of voltage-gated Na+ channels to open
Relative Refractory Period
Na+ channels from inactivated to closed
Membrane hyperpolarized, so needs greater depolarization
K+ channels that haven’t closed yet cause membrane potential to be more negative than resting potential
Synapses
Can be btw 2 neurons or neuron and organ
2 types: electrical and chemical
Electrical Synapses
Occur when the cytoplasms of 2 cells are joined by gap junctions
AP spreads directly from one cell to the other
More important in smooth and cardiac muscle
Chemical Synapses
Found at ends of axons where they meet target cell
Here, AP is converted into a chemical signal
Ex. neuromuscular junction
Transmission of signal across chemical synapse steps
- Ap reaches end of axon/synaptic knob
- Depolarization of presynaptic membrane open voltage-gated Ca2+ channels
- Ca2+ influx into presynaptic cell causes exocytosis of NT stored in secretory vesicles
- NT molecules diffuse across narrow synaptic cleft
- NT binds to receptor proteins in postsynaptic membrane. Receptors are ligand-gated ion channels
- Opening of ion channels (ions enter postsynaptic cell) in postsynaptic cell alters the membrane polarization (increases or decreases it)
- If membrane depolarization of postsynaptic cell reaches the threshold of voltage-gated Na+ channels, an AP is initiated
- NT in synaptic cleft is degraded and/or removed to terminate signal
Neuromuscular junction
NT released: ACh
When AP reaches synapse, ACH is released into synaptic cleft
ACH bind to ACh receptor on surface of postsynaptic membrane
When ACh binds to receptor, receptor opens Na+ channels and postsynaptic cell membrane gets depolarized
ACh left in synaptic cleft gets degraded by AChE (enzyme: acetylcholinesterase)
Other NTs
GABA, serotonin, dopamine, norepinephrine
Excitatory or inhibitory=depends on receptor, not NT
Ex. inhibitory=NT causes entry of Cl- into cell, which makes postsynaptic potential more NEGATIVE, or HYPERPOLARIZED, so NT=inhibitory
Summation
Addition of stimuli, multiple neurons that lead to synapse, how postsynaptic neuron “decides” to fire AP or not
Temporal Summation
Presynaptic neuron fires APs so rapidly that EPSPs and IPSPs pile up on each other
Spatial Summation
EPSPs and IPSPs from all synapses on postsynaptic membrane are summed at a given moment in time
PNS
Sensory function of nervous system Motor function (acting on info)
CNS
Integrative (processing info)
2 types of effectors
Muscles and glands (motor neuron that carry info AWAY nervous system)
Afferent neurons
Sensory neurons, carry info TO CNS
Muscle Stretch Reflex
Sensory neuron detects stretching of muscle , transmits an impulse to a motor neuron cell body in spinal cord
Sensory neuron synapses with a motor neuron for quads and also with an inhibitory interneuron (for hamstring motor neuron)
Monosynaptic Reflex Arc
Reflex involving only 2 neurons and one synapse
Reciprocal Inhibition
Ex. Relaxation of hamstring with contraction of quads
PNS Organization
Somatic (voluntary movement of skeletal muscle) and Autonomic (digestion, metabolism, circulation, perspiration, and other involuntary processes)
–> autonomic to (efferent portion): sympathetic (fight or flight) and parasympathetic (slow, rest and digest)
Cell bodies are ganglia
CNS
Neuronal cell bodies and bunched together to form structures called nuclei
3 Subdivisions of Brain
For, mid, and hindbrain
Spinal Cord
Site for info integration and processing
Responsible for simple spinal reflexes (muscle stretch reflex) and primitive processing like walking, urination, and sex organ functions
Hindbrain
Medulla, pons, and cerebellum
Medulla
Below pons, connects to spinal cord, relays info to other parts of the brain, regulates vital autonomic functions like blood pressure and digestive functions, also has respiratory rhythmicity center
Pons
Below midbrain, above medulla, connection point btw brain stem and cerebellum, controls some autonomic functions are coordinates movement, plays a role in balance and antigravity posture
Cerebellum
Behind pons, where complex movements are coordinated, instruction for movement from forebrain must be sent here
Damage results in poor hand-eye coordination and balance
Both this and pons receive info from vestibular apparatus in inner ear, which monitor acceleration and position relative to gravity
Midbrain
Relay for visual and auditory info and contains much of the reticular activating system (RAS), which is responsible for arousal and wakefulness
Forebrain
Includes diencephalon and telencephalon
Diencephalon
Hypothalamus and thalamus
Thalamus
Contains relay and processing centers for sensory info
Hypothalamus
Interacts directly with many parts of brain, contains center for controlling emotions, and autonomic functions, has major role in hormone production and release, primary link btw nervous and endocrine system, controls pituitary gland, so is fundamental control center for endocrine system
Telencephalon
2 separate cerebral hemispheres
Cerebrum
consists of the large, paired cerebral hemispheres
Hemispheres of cerebrum consists of cerebral cortex-outer layer of gray matter, plus an inner core of white matter connecting cortex to diencephalon
Gray matter=somas/cell bodies
White matter=myelinated axons
Frontal Lobe
Initiates all voluntary movement and is involved in complex reasoning skills and problem solving
Parietal Lobes
Involved in general sensations (touch, temperature, pressure, vibration, etc.) and in gustation (taste)
Temporal Lobes
Process auditory and factory sensation and a reimbursement involved in short-term memory, language comprehension, and emotion
Occipital Lobes
Process visual sensation
Broca’s Area
Speech Production
Wernicke’s Area
Language Comprehension
Basal Nuclei
Composed of gray matter and located deep within cerebral hemispheres
Include several functional subdivisions, but broadly function in voluntary motor control and procedural learning related to habits
Basal nuclei and cerebellum work together to process and coordinate movement initiated by the primary motor cortex; basal nuclei are INHIBITORY (prevent excess movement), while cerebellum is EXCITATORY
Limbic System
Btw cerebrum and diencephalon
Includes several substructures (amygdala, cingulate gyrus, and hippocampus) and works closely with parts of cerebrum, diencephalon, and midbrain
Important in emotion and memory