Nervous System Flashcards
Why myelin sheath?
To prevent signal loss and to speed up signals
Name of cell body in nervous system
Soma
What produces myelin?
Oligodendrocytes in the central nervous system and Schwann cells in the periphery
Resting membrane potential
-70, the inside is more negative
Which ion is in a high concentration inside the neuron
[K+]
What restores the potential after action potential
Na+, K+ ATPase
What is the ratio of Na K movement when restoring gradient
Three Na+ out for every 2 K+ in
Inhibitory inputs cause
Hyper polarization because it makes the cell more negative
Threshold value
-55 to -40 will make an action potential go
What is the first step of depolarization
Na+ channels open and follow a strong electric and chemical gradient for sodium to move into the cell. This causes the cell potential to become positive.
At what point do the sodium channels close after depolarization
+35
What is the trigger for potassium gates channels to open
Positive potential caused by opened Ca channels
When do potassium channels close after depolarization
Once membrane potential is restored, although sometimes it is overshot resulting in hyper polarization
The movement down an axon terminal is called
Pulse propagation
The longer the axon, the ____ the resistance and the ___ the conduction
Higher, slower
Is the entire membrane permeable?
No only at nodes of ranvier, causing skipping
What is the skipping down the membrane called
Saltatory conduction
How are neurotransmitters broken down in the synaptic cleft?
Some are broken down by enzymatic reactions some use reputable carriers to be recycled back into the presynaptic neuron
Afferent neurons
Neurons that carry information from the periphery to the brain or spinal cord.
Efferent neuron
Carry info from the spinal cord or brain to the body
Interneurons
Only involved in local circuits
Neural cell bodies that cluster in the peripheral nervous system
Ganglia
Neural cell bodies that cluster in the central nervous system
Nuclei
Components of the central nervous system
Brain and spinal cord
White matter
Unmyelinated axons
Components of the forebrain
Telencephalon and diencephalon
Gray matter
Unmyelinated cell bodies and dendrites
Components of telencephalon
Frontal, parietal, occipital, and temporal lobes
Function of cerebral cortex
Gray matter for highest level functioning including creative thought and future planning. Integrates thought and controls movement.
How to hemispheres communicate
Corpus callosum
Components of the diencephalon
Thalamus and hypothalamus
Function of the thalamus
Gateway for all sensory information
Function of hindbrain
Many involuntary functions
Components of the hindbrain
Cerebellum, pond, and medulla which make up brain stem
Function of cerebellum
Quality control agent. Checks that the motor signal sent from the cortex is in agreement with the sensory information from the body
The most highly conserved part of the brain
Medulla
Function of medulla
Ventilation rate, heart rate, gastrointestinal tone
Why do people stumble when drink
It has massive effects on cerebellum
Four regions of the spinal cord
Cervical, thoracic, lumbar, and sacral
Monosynaptic reflex arc
Single synapse.
Polysynaptic reflex arc
At least one interneuron between the sensory and motor neuron.
Major difference between SNS and ANS
ANS is a two neuron system. The first is preganglionic and the second is postganglionic
What do the neurons use in the sympathetic nervous system
Preganglionic uses acetylcholine and postganglionic uses norepinephrine
What neurotransmitters does the parasympathetic nervous system use
Acetylcholine, the vagus nerve is also responsible for many thoracic and abdominal effects.
How is pain detected
Nociceptors
How is the eye supplied with nutrients and oxygen
Choroid
What adjusts the thickness of the lens
Ciliary muscles
What are the two eye photoreceptors and what do they detect
Rods - transmission of black an white images and low intensity illumination. Only pigment is rhodopsin
Cones - color images
After excitation with light how to photoreceptors relay signals
Send signal to bipolar cells which send info to retinal ganglion cells which bundle to form optic nerve
Function of the outer ear
Collects waves and channels them to the tympanic membrane
Three components of the middle ear
Malleus, incus, and stapes
Function of midear
The midear vibrates and sends sounds to the cochlea and semicircular canals
Function of hair cells in inner ear
They are depolarized and send an electric signal to the auditory nerve of the brain
Which part is a key for balance
Semicircular canals filled with endolymph
Where do sensory neurons synapse
Dorsal spinal cord
Where do motor neurons synapse
Ventral spinal cord
Which structure in the ear transducers pressure wars to action potentials
Organ of corti
