Bio: The Nervous and Endocrine Systems, Neurotransmitters, Parts of Brain Flashcards
Dendrites Soma Myelin (what is it actually?) Schwann cells oligodendrocyte Axon hillock The impulse is send from what to what?
Dendrites send impulse to soma
Soma is basically where nucleus is and protein is made
Myelin = a CELL and insulator, so can increase speed of impulse transmission (Schwann cells serve as the myelinating cell of the PNS (they literally make the myelin) vs oligodendrocyte is name of myelin in CNS)
and “jumps” over nodes of ranvier -> saltatory conduction
Axon hillock connects soma to axon
impulse send from dendrites to axon terminus and all the way to the synaptic knobs
What is the difference b/w unipolar, multipolar, and bipolar neurons
Unipolar -> Looks like soma in middle with regular axon terminal and multiple dendrites (sensory neuron)
Multipolar -> neurons with many dendrites (one we’re used to) (motor neuron)
Bipolar -> neurons with one dendrite (interneuron)
What is resting membrane potential and what perspective is it always from? That is threshold when Na+ voltage gated channels and K+ voltage gated channels open? Describe the channels you see in membrane and how this allows for this specific resting membrane potential
What happens when threshold is reached to Na+ and K+ voltage gated channels?
RMP = - 70mV
Threshold is -50mV
NOKIA321
Na+/K+ ATPase pumps out one net positive ion out
Na+/K+ ATPase establishes Na+ and K+ concentration gradients
many pos ions are lost through K+ leak channels (K+ leaks out of cell) (like “K bye”)
end result is that cell is more neg inside than out (-70mV)
in addition to these channels, there is K+ voltage gated channel and Na+ voltage gated channel but these only open when threshold is reached (-50mV) -> **When hit threshold Na channel works right away but K channel delayed, feel effect of Na first and it rushes inside down gradient
Depolarization, hyperpolarization, repolarization
Equilibrium potential
What does the action potential look like, using the top 3 terms above?
Impulse is all or nothing
Depol -> move away from rest potential in the pos direction
Hyperpol -> move away from rest potential in neg direction
Repol -> return to rest potential
Equilibrium potential -> potential at which there is no driving force on an ion
Action potential:
Depolarization -> repolarization -> hyperpolarization -> repolarization
Why is the impulse unidirectional?
What is the absolute and relative refractory period/ what is open/closed/inactivated? when do they occur?
What happens if add electrode in middle of axon?
Absolute refractory period -> absolutely impossible to fire another action potential, Na+ channels are inactivated, cell is too positive, near Na+ equilibrium potential
Relative refractory period -> possible but difficult to fire a second action potential, Na+ channels are now closed, cell it too neg, further from threshold, near K+ equilibrium potential
The impulse is unidirectional bc of the refractory period which begins when Na channels are inactivated (when membrane potential is repolarizing) and a neuron CANNOT fire another action potential no matter how strong a membrane potential depolarization is bc the voltage gates Na+ channels are inactivated after depolarization. They will not be able to be opened again until the membrane potential reaches the resting potential and the Na+ channels have returned to their “closed” state.
During the relative refractory period (right after the absolute refractory period), a neuron can be induced to transmit an action potential, but the depol required is greater than normal bc the membrane is hyperpolarized
If added electrode to middle of axon, impulse can go in either direction -> neither side is in refractory period
Electrical synapses are ___junctions, always/sometimes excitatory, bidirectional, unregulated/regulated
common/rare in nervous system
very important to the organ system(s):
Electrical synapses are gap junctions, always excitatory, bidirectional (either cell can be pre/post synaptic, unregulated
Rare in nervous system, VERY IMPORTANT IN CARDIAC MUSCLE CELLS and smooth muscle
Chemical synapse Are excitatory/inhibitory, Synapsin bonds? Cytoskeleton filaments? How is Ca2+ involved?
Chemical synapse is opposite of electrical synapse
Can be excitatory or inhibitory, normal thing we find in nervous system
Synapsin bonds Keeps cytosketeton filaments and vesicles bound and these synapsin bonds can be broken by Ca2+
- There are Ca2+ voltage gated channel so that only when action potential arrives, can stimulate these voltage gated channels to open, so that Ca2+ (commonly found outside of cell) can go inside to break these bonds
What is SSRI (selective serotonin re-uptake inhibitory?
Given: K+, Na+, Cl-, Mg2+, PO4 3-, Ca2+ -> where can the greatest concentration of these be found, inside or outside of neuron?
SSRI -> serotonin can stay in synaptic cleft for longer
Inside: k+, Mg2+, PO43-
Outside: Na+, Cl-, Ca2+
and these ions flow from high to low concentrations once certain channels open
*If you want to know how post synaptic cell will respond, what do you need to look at?
What is the difference between an inhibitory and excitatory neurotransmitters?
If a neurotransmitter causes entry of chloride into the postsynaptic cell, is the neurotransmitter excitatory or inhibitory?
NEED TO LOOK AT RECEPTOR, NOT NEUROTRANSMITTER -> EX GABA -> has “inhib effects” bc it bind to chlorine receptors
If a neurotransmitter such as acetylcholine is released at neuromuscular junction (b/w neuron and muscle cell) binds to its receptor on post synapic membrane, the receptor opens its associated sodium channel, allowing sodium to flow down its gradient into the cell, depolarizing the postsynaptic cell membrane . If a neurotransmitter such as acetylcholine opens a channel that depolarizes the postsynaptic membrane, the neurotransmitter is termed excitatory
Other neurotransmitters however, have the opposite effect, making the post synaptic membrane potential more negative than the resting potential or hyperpolarized so these neurotransmitters are called inhibitory
Chloride ions are negatively charged so entry into the cell would make the postsynaptic potential more negative, or
What does Acetylcholinesterase do?
degrades acetylcholine
Neurons make one/more than one NT, and can respond to one/many
T/F: the amount of time neurotransmitter is in synaptic cleft adjusts response
T/F: takes more than one NT to have a significant effect on the postsynaptic cell
Neurons make one NT, and can respond to many
T
T
IPSP (inhibitory postsynaptic potentials) and EPSP (excitatory postsynaptic potential)
See printed out diagram
Get a mini depolarization from lil bit of neurotransmitter dumped to open ex. Na channel (green in diagram) = EPSP
But if dump more and more neurotransmitter to bind and open Na channel (green) then get past threshold and get large action potential peak
Get mini hyperpolarizaiton for chlorine receptor bc Cl-makes membrane potential more neg (red in diagram) =IPSP
But when bombarded with neurotransmitter to chlorine receptor get large hyperpolarization
What is idea of summation?
Spatial vs Temporal?
What influences the intensity of a action potential?
Action potential is an all or nothing event
A post-synaptic neuron has many different neurons with synapses leading to it, however, each of these synapses can release neutrotransmitter many times per second. The “decision” by a possynaptic neuron whether to fire an action potential is determined by adding the effect of all of the of the synapses impinging on a neuron, both excitatory and inhibitory. This addition of stimuli is termed summation.
Spatial summation -> add up EPSPs and IPSPs from all the synapses on the post synaptic membrane are summed at a moment in time and majority rules (will tell you if overall excitatory or inhibitory)
Temporal summation -> add up frequent impulses from a single source, so basically a presynaptic neuron fires action potentials so rapidly that EPSPs or IPSPs
Intensity is coded by frequency
What happens if an inhibitor of acetylcholinesterase is added to the neuromuscular junction, then the postsynaptic membrane will…
a) be depolarized by action potentials more frequently
b) be depolarized longer with each action potential
c) spontaneously depolarize
B
What does afferent/efferent neuron mean? Where do they come from/go and why? Afferent neuron? Ventral root? Dorsal root?
afferent neurons = approaching the CNS from PNS
Efferent neurons = exit CNS to PNS
Dorsal = “enter through doors” and enter CNS
Ventral root = “leave through vents” and leave CNS
- Sensory info coming into CNS from PNS and carried on sensory neurons = afferent neurons (dorsal)
- Integration in CNS -> decision making, interneurons (entirely contained within CNS)
- Motor output (PNS) -> commands sent out to the body and carried on motor neurons (efferent neurons) exiting the CNS
What are you able to feel/do if you cut dorsal root and get thumb injury?
If cut dorsal root, you can’t feel thumb but can move it
Reflex -> what part of nervous system does it include?
What type of neuron is sensory neuron?
Motor neuron = _____neuron
Sensory neuron =____neuron
rapid integration to avoid potential injury
connects muscle to spinal coral
Sensory neuron is unipolar (weird looking one with head in middle)
For kick flip reflex -> you sense pressure from sensory neuron (afferent neuron), signal sent to spinal cord, and directly to motor neuron (efferent neuron) which causes quad muscle to contract and at the same time sensory neuron also sends signal to inhibitory interneuron which then sends signal to efferent motor neuron to relax the hamstring muscle, both of these actions cause you to kick up
Reflex -> what part of nervous system does it include? What type of neuron is sensory neuron? Reciprocal inhibition (book) Motor neuron = \_\_\_\_\_neuron Sensory neuron =\_\_\_\_neuron
rapid integration to avoid potential injury
connects muscle to spinal coral
Sensory neuron is unipolar (weird looking one with head in middle)
For kick flip reflex -> you sense pressure from sensory neuron (afferent neuron), signal sent to spinal cord, and directly to motor neuron (efferent neuron) which causes quad muscle to contract and at the same time sensory neuron also sends signal to inhibitory interneuron which then sends signal to efferent motor neuron to relax the hamstring muscle, both of these actions cause you to kick up
This is called reciprocal inhibition
Motor neuron = efferent neuron
Sensory neuron = afferent neuron
Dicephalon Hypothalamus Pons Medulla Spinal cord Cerebellum Midbrain Limbic system Telencephalon Corpus callosum
continues on next card
These can be labeled counter clockwise on brain diagram starting from top left
Dicephalon -> forebrain and includes thalamus and hypothalamus
- thalamus contains relay and processing center for sensory info
- Hypothalamus interacts with various parts of brain -> Maintains body homeostasis, contains centers for controlling emotions and autonomic functions and hormone regulation, controls pituitary gland
Telencephalon -> consists of two separate cerebral hemispheres, the cerebral hemispheres are connected by a thick bundle of axons called the corpus callosum
The telencephalon consists of two separate cerebral hemispheres, generally speaking the areas of the left and right hemispheres have the same functions. But the the left hemisphere controls the motor functions of the right side of the body, and the right hemisphere controls those of the left side. The left side of the brain is said to be dom and is responsible for speech, right hemisphere more concerned with visual-spatial reasoning and music.
Pons -> facial movement, balance, posture
Medulla -> basic vital/involuntary functions -> controls autonomic processes such as blood pressure, blood flow, HR, respiratory rate, swallowing, vomiting, cough, hiccup
Spinal cord -> simple reflexes, controls primitive processes such as walking, urination, and sex organ function
Cerebellum -> coordination of complex movement, BALANCE
(damage here result in poor hand eye coordination and balance)
Midbrain -> visual and auditory info, wakefulness and consciousness, startle reflex
Limbic system -> psychological response to emotional stimuli, helps memory storage
Cerebrum/Cerebral cortex
*cerebral cortex is the outer layer of the cerebrum
cerebral cortex is an outer layer of gray matter plus an inner core of white matter connecting the cortex to the diencephalon
Cerebral cortex -> divided into 4 lobes (frontal, parietal, temporal, and occipital with specialized functions)
Frontal lobes initiate all voluntary movement, involved in complex, reasoning skills (judgement) and problem solving
Parietal lobes are involved in sensations (such as touch, temperature, pressure, vibration, etc.) and gustation (taste)
The temporal lobes process auditory (hearing), olfactory sensation and are involved in short-term memory, language comprehension, and emotion
The occipital lobes process visual sensation
What makes the brain stem?
Midbrain, Pons, Medulla
Epithalamus
Thalamus
Hypothalamus
Epithalamus -> pineal gland secretes melatonin - involved in sleep/wake cycles
Thalamus -> sensory relay station: sensory info come here first then gets distributed, relay info b/w spinal cord and cerebral cortex, EXCEPT: olfactory info (smell goes to olfactory bulbs)
Hypothalamus - (repeated from previous flashcard) interacts with various parts of brain -> Maintains body homeostasis, contains centers for controlling emotions and autonomic functions and hormone regulation, controls pituitary gland
*White matter (IMPORTANT)
Gray matter
Memorize where white and gray matter is found in CNS vs PNS
White matter - myelinated portions of the nervous system (axon), cell to cell communication
CNS-brain = tract
CNS- spinal cord = tract/column (looks like outside portion of spinal cord lighter in diagrams)
PNS = nerve (duh)
Gray matter - soma; unmyelinated cell bodies and dendrites; (integration stations)
CNS-deep brain = nucleus (a cluster of neurons in the central nervous system, located deep within the cerebral hemispheres and brainstem)
CNS-brain surface = cortex
CNS- spinal cord = horn (looks inside portion of spinal cord darker in diagrams)
PNS = ganglion (leads to spinal cord)
*What does a brocas injury do? Wernickes area injury?
What is a nerve tract?
A brocas injury -> can’t make speech
Wernickes area injury -> can’t comprehend speech
-> Makes yo say what?! Left temporal lobe
CNS is organized in bundles called tracts, or fasciculi. Ascending tracts carry impulses along the spinal cord toward the brain, and descending tracts carry them from the brain or higher regions in the spinal cord to lower regions.
Nervous splits into CNS vs PNS then what does PNS split into? Then what does one of those options split into?
CNS vs PNS
PNS -> somatic (voluntary control of skeletal muscle) vs Autonomic (involuntary control of glands and smooth muscle)
Autonomic -> Sympathetic (“fight or flight”) vs parasympathetic (“rest and digest”)
Somatic vs autonomic: Voluntary/invol? What types of organs/tissues involved? What neurotransmitters involved? Excitatory, inhibitory? How does signal get sent from CNS to target in terms of number neurons?
Dorsal root ganglion
Somatic -> voluntary, muscles, acetylcholine ONLY, excitatory, single neuron from CNS to target organ and all somatic sensory neurons have a long dendrite extending from the sensory receptor toward the soma, which is located outside the CNS in a dorsal root ganglion
Autonomic -> involuntary, all other organs, acetylcholine or norepinephrine (also known as noradrenaline)
-> For autonomic there are 2 neurons -> one ends in norepinephrine (sympathetic) and the other in acetylcholine (parasympathetic) (either stimulate or inhibit)
Acetylcholine vs norepinephrine
When, where is epinephrine/adrenaline released?
Acetylcholine = parasympathetic, rest and digest Norepinephrine = sympathetic, fight or flight
Upon activation of the sympathetic system, the adrenal gland is stimulated to release epinephrine, also known as adrenaline
Golgi tendon organs
Golgi tendon organs sense tension in tendons when lift something
It responds to increased muscle tension or contraction as exerted on the tendon, by inhibiting further muscle contraction.
5 classes of Sensory Receptors: Mechanoreceptors Chemoreceptors Thermoreceptors Nociceptors Photoreceptors/Electromagnetic receptors
Where would muscle spindle, O2 receptors, taste buds, olfactory sensors, golgi organs, rods/cones fit?
Mechanoreceptors -> stim by physical shape changes e.g. baroreceptors, golgi tendon organs, touch receptors, muscle spindle (detect muscle stretch) etc.
Chemoreceptors -> stimulated by chemicals
e.g. olfactory sensors, taste buds are gustatory receptors, pH receptors, O2 receptors, etc.
Thermoreceptors -> stimulated by temperature
e.g. hot and cold receptors
Nociceptors: stimulated by pain
free nerve endings that respond to touch, chemicals, heat, etc.
Photoreceptors/Electromagnetic receptors: stimulated by light e.g. rods and cones
Absolute threshold
Difference threshold
Absolute threshold -> MINIMUM stimulus required to trigger a receptor
ex. Dog has lower absolute threshold and can smell better
Difference threshold -> amount of change that is required to occur before we notice it ex. you forgot you were wearing clothes bc no change detected. The minimal noticable difference b/w any two sensory stimuli
Sensory Adaption
Bottom-Up processing
Top-Down processing
Sensory Adaption -> is a decrease in firing frequency when the intensity of a stimulus remains constant, ignore unchanging stimuli, can be retriggered if stimulus change
Bottom-Up processing ->
- Sensory receptors register info
- Sensory neuron send info to the bran
- Brain identifies the info
Top-Down processing
- Brain applies prior knowledge and experience
- Forms a holistic view of what’s going on
Iris
Lens
Cornea
Pupil
Iris -> colored part of eye. regulates the diameter of pupil
Lens -> biconvex structure that focuses light on the retina
Cornea -> external transparent layer of eye
Pupil -> black opening in middle of eye
Ciliary Muscles Fovea centralis retina optic disk optic nerve
Ciliary Muscles -> muscles that regulate the curvature of the lens
Fovea centralis -> responsible for extreme visual acuity (highest density of cones) when you look directly at something, you focus its image on the fovea
retina -> layer at the back of eye sensitive to light
optic disk -> blind spot. Place on retina where optic nerve forms -> Blind spot has many ganglion cells so blocks light and you are blind there
optic nerve -> bundle of axons leaving the eye towards the brain
Where does the signal go from retna?
Goes to photoreceptors (rods or cones) then to bipolar cells then to ganglion cells then to occipital lobe of cerebral cortex (image processing)
No light can pass through region when ganglions are bc blocks
Where does the signal go from retna?
What happen in dark vs light and on center vs off center?
Goes to photoreceptors (rods or cones) then to bipolar cells then to ganglion cells then to occipital lobe of cerebral cortex (image processing)
No light can pass through region when ganglions are bc blocks
Bc of the rods and cones depolarization in the dark, both types of photoreceptors release the neurotransmitter glutamate onto the bipolar cells. Upon the absorption of a photon of light and subsequent hyperpolarization, the photoreceptor release less glutamate, or stop releasing it altogether
Some bipolar cells are “on center” and are inhibited by glutamate. This means that when the photoreceptor is in the dark and releasing glutamate, the on-center bipolar cell releases very little or no neurotransmitter. However, when the photoreceptor is in the light (light is ON the center), and stops releasing glutamate, the inhibition of the on-center bipolar cell stops, and the bipolar cell increases its release of neurotransmitter. “Off center” bipolar cells work in the opposite manner; they are stimulated by the glutamate released when the photoreceptor is in the dark, and inhibited when glutamate stops being released in the light
Dark, on center -> no action potential
Dark, off center -> action potential
Light, on center -> action potential
Light, off center -> no action potential
Ear terms (know parts of ear) Pinna Auditory canal Typanic membrane Ossicles Malleus Incus Stapes Semicircular canals Cochlea Eustachian tube
The pinna and auditory canal = outer ear Typanic membrane = ear drum Three small bones -> called ossicles = Malleus, Incus, Stapes Eustachian tube (auditory tube) -> connects throat with middle ear, allows pressure to be equalized
How do we hear?
Perilymph and endolymph?
Basilar membrane
Tectorial membrane
- Sound waves go down auditory canal and bounce on timpanic membrane
- This causes auditory ossciles to vibrate back and forth
- Which sends waves to fluid in cochlea (the outer structures filled with fluid called perilymph), waves sent to perilymph which then send waves down central region called endolymph
- Then we get vibration in basilar membrane (supports receptors called hair cells) and movement of hair cells
- The hair cells are in contact with the tectorial membrane (stationary) and cilia of hair cells are dragged across the tectorial membrane
- hairs get bent and since they are mechanoreceptors, they release neurotransmitter onto auditory nerve
- Auditory neuron transmits the signal to the brain
How do we determine pitch from loudness?
These are determined by which region of basolar membrane that gets stimulated most strongly
high pitch tones are high freq
and low pitch tones are low freq
Thick at “base” and thin at “leaves” like a tree
at the beginnign part of basolar membrane, it is very stiff and thick and at end it’s thinner, floppy
a low freq pitch/tone do not have enough strength to vibrate the thick part of membrane
and high freq tone are better at vibrating the thicker beginning part of membrane
Depending on which region of basolar membrane is most stimulated, the brain can interpret pitch
Loudness is determined by amplitude -> soft sound, small amplitude, loud sound, larger amplitude
Semicircular canals
Vestibule
Semicircular canals -> important for rotational equilibrium/dynamic equilibrium ex. 3D space of head, head turning, spinning
Vestibule -> important for static equilibrium ex. forward momentum, no spinning but plane of equilibrium shifting when chair you were sitting in started leaning backwards
Summary: From sound to Hearing
Sound waves -> auricle -> external auditory canal -> tympanic membrane -> malleus -> incus -> stapes -> oval window -> perilymph -> endolymph -> basilar membrane -> auditory hair cells -> tectorial membrane -> neurotransmitters stim bipolar auditory neurons -> brain -> perception
Vestibular complex
Semicircular canals
Vestibule
Semicircular canals -> important for rotational equilibrium/dynamic equilibrium ex. 3D space of head, head turning, spinning
Vestibule -> important for static equilibrium ex. forward momentum, no spinning but plane of equilibrium shifting when chair you were sitting in started leaning backwards
Equilibrium potential for K+?
*Gray vs White matter? Horn? Tract? Column? Nucleus?
-90mV
White matter = myelinated axons in CNS and PNS
White matter in brain = a tract
White matter in spinal cord = tract or column
White matter in PNS = nerve
Gray matter = Unmyelinated cell bodies in CNS and PNS
nucleus = gray matter in brain
Cortex = gray matter on the surface of brain
Horn = gray matter in spinal cord
Ganglion = gray matter in PNS
What is a proprioreceptor?
Muscle spindle?
Proprioreceptor refers to awareness of self (i.e. awareness of body part position) and is known as your kinesthetic sense
An important example of a proprioreceptor is the muscle spindle, a mechanoreceptor that detects muscle stretch
Other proprioreceptor includes Golig tendon organs which detect tension in tendons
extra?
Myopia
Hyperopia
Myopia -> nearsightedness, too much refraction at the lens or an abnormally long eyeball results in a focal length that is too short
Hyperopia -> farsightedness, too little refraction at the lens or an abnormally short eyeball results in a focal length that is too long
What does the posterior pituitary do? Anterior? Do they make/secrete hormones?
posterior -> composed of axons which descend from the hypothalamus, these hypothalamus neurons are an example of neuroendocrine cells (neurons which secrete hormones into the bloodstream) doesn’t make hormones, it just stores ADH and oxytocin for later release
anterior is a normal endocrine gland and is controlled by hypothalamic releasing and inhibiting factors (tropic hormones)
Basal nuclei (also called "cerebral nuclei" or basal ganglia function?
composed of gray matter and located deep in cerebral hemispheres
Regulate body movement and muscle tone, coordination of learned movement patterns, general rhythm movements (arm and leg movements when walking)
The basal nuclei and cerebellum work together to process and coordinate movement initiated by the primary motor cortex; the basal nuclei are inhibitory (preventing movement), while cerebellum is excitatory
Name function of following neurotransmitter(s):
Dopamine
Seratonin
Melatonin
Dopamine -> reward, mood, pleasure, smooth motor movements, focus and attention, shortages can lead to depression, lethargy and difficulty coordinating motion
Seratonin -> Mood stabilizer, Mood, digestion, sleep, memory, sexual desire, shortages can lead to: aggression, compulsive behavior, overeating, and depression
Melatonin -> circadian rhythm, sleepiness, sleep initiation (melatonin is technically a “neurotransmitter-like substance”, shortages lead to insomnia
Name function of following neurotransmitter(s):
Gamma Aminobutyric Acid (GABA)
Acetylcholine
GABA -> Primary inhibitory neurotransmitter in the brain, shortages can lead to stress and anxiety, depression, ADHD, Panic Disorders, etc
Acetylcholine -> excitation at neuromuscular junction, parasympathetic nervous system activity
Shortages can lead to dysfunction of Gi tract and paralysis
Name function of following neurotransmitter(s):
Epinephrine (adrenaline)
Norepinephrine (noradrenaline)
Glutamate
Two similar molecules both involved in fight or flight response, sympathetic nervous system activation (both are hormones and neurotransmitters)
Shortages can lead to fatigue, lack of focus, apathy
Glutamate -> primary excitatory neurotransmitter in brain, learning, memory, long-term potentiation
Shortages can lead to fatigue, low concentration and energy
