Lecture Test 5

monitor the internal environment

monitor the exterior environment

are always open and allow specific ions to flow across.

is the maintenance of this separation of electrical charge across the membrane while the cell is at rest (or not conducting an action potential).

allow for the control of ion flow across the membrane

• 1. Chemically gated channels
• 2. Voltage gated channels
• 3. Mechanically gated channels

open and close in response to the presence of specific chemicals like neurotransmitters and drugs (ie. nicotine, caffeine).

Think of a locked door as the channel and the key as the drug or NT.

open at specific voltages and close at specific voltages.

Think of pass keys to electrical gates at an apartment complex.

open in response to mechanical or physical distortions of the cell membrane.

Think of the air nozzle on a child's arm floats.

stimulus to open/close: always open

comment: establish RMP

stimulus to open/close: excititory Neurotransmitter

comment: they can depolarize neurons

stimulus to open/close: inhibitory neurotransmitters

comment: they hyperpolarize neurons

stimulus to open/close: -60 mv open / +30mv close

comment: they cause action potentials

stimulus to open/close: +30mv open / -70mv close

comment: they are part of the action potential

stimulus to open/close: open with action potential and close with action potential is gone.

comment: they are at the synaptic knob

stimulus to open/close: open in response to mechanical or physical distortions of the cell membrane.

the voltage necessary to begin opening voltage gated channels

a small localized change in the RMP

if the NT opens a sodium channel, sodium ions will enter the cell, the neuron will become more positive inside and is said to excite or become depolarized or have an EPSP

if the NT opens potassium channels, potassium ions will exit the cell; the neuron will become more negative and is said to hyperpolarize or have an ISP.

adding several graded potentials together to increase the strength

• 1. temporal
• 2. spatial

one synapse, over a period of time, can continually release NT, holding chemically gated channels open for extended periods.

results from simultaneous stimulation of numerous synapses to add either EPSP's or IPSP's together

occurs when a chemical (drug or NT) raises the RMP closer to threshold for a period of time.

anything that alters resting membrane potential

is a self-propagating (pushing) wave of voltage that will pass down the entire length of the neuron.

is the level of depolarization (millivoltage) necessary to cause an action potential

any stimulus that brings the neuron to threshold will cause an action potential.

there is no turning back

• 1. depolarized to threshold
• 2. rapid depolarization
• 3. repolarization
• 4. hyperpolarization
• 5. return to RMP

a chemical stimulus opens chemically gated sodium channels to open, causing a depolarizing graded potential. If the graded potential reaches threshold (-60mV), voltage gated sodium channels begin to open.

sodium ions enter the cell making it more positively charged inside. The depolarizing continues to +30mV, the voltage at which all voltage gated sodium channels are closed.

at +30mV potassium channels are opening and potassium ions are flowing out of the cell making it less positively charged inside. This continues until the cell reaches -70mV.

at -70mV potassium channels begin to close, but do so very slowly, allowing excess potassium ions to leak out of the cell causing it to hyperpolarize to -90mV.

the sodium/potassium pump restores resting membrane potential

the period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied

the period shortly after the firing of a nerve fiber when partial repolarization has occurred and a greater than normal stimulus can stimulate a second response

is when enough voltage spreads it can cause the next patch of membrane (floor tile) to reach threshold potential and fire an action potential identical to the last one. This will then cause the next patch (tile) and the next and the next to spread this action potential across the entire cell (floor).

is the spreading of the action potential across the cell

once an action potential is started in one patch of membrane it will automatically spread down the entire axon, and there is no turning back or stoppig it until it reaches the synaptic knob

action potential velocity is dependent upon the flow of ions (voltage) through the axon.

the larger the axon diameter, the faster the action potential can travel down the axon.

form a sheath around peripheral axon. And are filled with a fatty substance called myelin

a small gap between the Schwann cells

is when the action potential jumps from one node of Ranvier to another

• 1. an action potential arrives at a synaptic knob and opens voltage gated Ca⁺ channel.
• 2. Ca⁺ ions diffuse into the synaptic knob and cause synaptic vesicles filled with neurotransmitter to bind to the cell membrane, releasing NT into the clef.
• 3. the NT diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane, altering RMP of the postsynaptic cell.
• 4. the postssynaptic membrane releases an enzyme to break down the NT, ending the signal. The postsynaptic cell returns to RMP.

• mechanism of action:
• excitatory in Sk Muscle (opens Na⁺ channels)
• inhibitory in cardiac muscle (opens K⁺ channels)

distribution (CNS, PNS):

CNS & PNS

mechanism of action:

usually excitatory (opens Na⁺ channels)

distribution (CNS, PNS):

CNS & PNS (sympathetic)

mechanism of action:

• inhibitory to motor neurons (low- Parkinson's)
• excitatory in emotional & pleasure centers (feel good NT)

distribution (CNS, PNS)

CNS

form blood/brain barrier

monitor and alter (form) CNF (cerebrospinal fluid). found lining ventricles & central canal of the spinal cord

myelinate axons in central nervous system

modified immune cells that remove debris, toxins, and pathogens from the central nervous system

surround neuron cell bodies in ganglia

nucleus or center

ganglion

is made up of somata (cell bodies of neurons) and unmyelinated axons. it appears darker or gray in color due to the lack of myelination.

is made up of myelinated axons

cantains nuclei and centers that control basic vital functions like breathing, heart rate, and digestive functions

is a bridge to the cerebellum. houses to centers that are involved in regulating respiratory rhythms

it coordinates somatic motor patterns and muscle memory like dancing, juggling, shooting a basketball, playing a musical instrument, etc. it also controls posture and balance and make rapid adjustments in body position to maintain balance for standing and walking.

• 1. Medulla
• 2. Pons
• 3. Cerebellum
• 4. Midbrain
• 5. Diencephalon

contains the corpora quadrigemina

coordinate visual reflexes (this would include turning your head when something moves in the periphery to see if it is possible mate or predator)

coordinate auditory reflexes (this would include turning your head toward a loud noise to see what caused it)

hypothalamus and thalamus

contains numerous center or nuclei that regulate the internal environment including body temperature, hunger, sex drives, and hormones. it secretes several hormones (endocrine secretions) and therefore coordinates the activities of the nervous and endocrine systems.

filtering and relaying sensory information to the cerebral cortex

it secretes a hormone called melatonin that helps regulate circadian (day/night) rythms

• 1. establish out emotional state
• 2. facilitate conversion of short term memory into long-term memory
• 3. storage of long-term memory
• 4. retrieval of memory

converts short-term memories into long-term memories also, stores long-term memories and functions in memory recall

performs intellectual functions like thinking and problem solving and is cered by the outer gray matter (the "thinking" neurons

contains the primary motor cortex and control voluntary (somatic) motor movements.

is the primary sensory cortex and receives sensory information

interprets smells, and auditory cortex that interprets sounds

visual cortex that interprets what we see

area that lies just anterior to the precentral gyrus called the premotor cortex and coordinates contractions of muscles necessary to vocalize (speak)

sequential events (what happens first, next, and then last) and cause and effect situations (if I do this, then that happens)

interpreting speech, reading, and writing, as well as analytical tasks like math, logic, and science.

interpreting non-verval sounds (music, bird chirps, barking dogs) and visual information (shapes, colors, forms)

• 1. deliver nutrients, ions, and oxygen to neurons and glia
• 2. removes waste and toxins
• 3. acts as a shock absorber

CSF is filtered out of the blood at a special network of capillaries called the choroid plexus and then circulates in the two latteral ventricles.

it then drains through the interventricular foramen into the third ventricle.

from the third ventricle it drains through the cerebral aqueduct (also called the mesencephalic aqueduct) into the fourth ventricle.

when CSF leaves the fourth ventricle it flows into the central canal and through openings called apertures into the subarachnoid space.

CSF is reabsorbed into veins surrounding the brain and then into the superior sagittal sinus.