BS -1 Neuro (part one)

Neuroglia
-definiton

non-neuronal cells in the nervous system that provide support and protection for neurons.

List the neuroglia cells:

1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ependymal cells
5. Schwann cells
6. Non-myelinated Schwann cells
7. Satellite Glial cells

Astrocytes
-function x 6

-fill the spaces between neurons and surround the blood vessels in the CNS
-transport of nutrients
-glycogen storage
-component of blood-brain barrier
-maintenance of extracellular K+ (keep K+ low extracellularly by absorbing it-- so that K+ is higher inside cells)
-information processing and memory storage

Oligodendroglia
-fx x 3

-Cells that make and maintain myelin within the CNS
-A single oligodendrocyte myelinates MANY neurons

Can oligodendrocytes regenerate?

-No ability to regenerate --> multiple sclerosis

One oligodendrocyte has touch points on (one or multiple) neurons

Multiple

Microalgia are:

specialized macrophages that remove debris / pathogens in the CNS

Ependymal cells fx x 3

-line the ventricles and choroid plexuses (columnar epithelial cells w/ cilia)
-Involved in production of CSF
-Helps circulate CSF

Schwann cells fx x 2

-form and maintain the myelin sheath (like oligodendrocytes) but in the PNS
-A single Schwann cell myelinates a single neuron (1:1 ratio unlike oligos)

Can Schwann cells regenerate?

YES! Schwann cells can regenerate...

Non-myelinating schwann cells:

Metabolic support and regeneration

Satellite glial cells fx x 1

-similar to astrocytes but in the PNS

Neurons

-electrically excitable cells
-primary info and communication cells of nervous system
-variable size and structure and polarity

Neurons cellular constituents:

1. microtubules
2. neurofibrils
3. nissl substances

________ are cellular constituents in neurons that give structural support

neurofibrils

________ are cellular constituents in neurons that allow them to transport

microtubules

________ are cellular constituents in neurons that allow for protein synthesis

Nissl substances (basically rough ER in neurons)

The three components of neurons:

1. Cell body
2. Dendrites
3. Axon

Cell bodies of neurons are mainly in the:

CNS (Brain and spinal cord)

______ are densely packed cell bodies in the CNS

Nuclei

_________ and _________ are groups of cell bodies and fibers (tracts) in the PNS

ganglia and plexus

_______ are the receptive portion of neurons that send impulses toward cell body

Dendrites

___________ contain the nucleus and are responsible for maintaining the neuron and processing signals

cell bodies

_______ transport materials to and from cell body and carry nerve impulses away from cell body

Axons

___________ area where the axon leaves the cell body

Axon hillock

Axon hillock:

-Axon hillock is the most electrically sensitive part of the neuron bc it has the highest number of voltage gated channels

Axon hillock has the (lowest or highest) threshold for excitation

LOWEST --> most electrically sensitive

Action potentials typically begin at:

Axon Hillock

______ is the segmented layer of insulating lipid material that INCREASES the speed of electrical conduction

Myelin

Myelin is formed and maintained by:
_______ in the PNS
_______ in the CNS

Myelin is formed and maintained by
-Schwann cells in the PNS
-Oligodendrocytes in the CNS

________ are regular interruptions of the myelin sheath that allow the electrical signal to jump from place to place

Nodes of Ranvier

___________ is the process by which electrical impulses "jump" from one Node of Ranvier to the next along a myelinated axon that significantly increases the speed of nerve impulse transmission

Saltatory conduction

_________ is where the action potential terminates

Axon terminal

What happens at the axon terminal once the action potential terminates

-AP reaches the axon terminal
-triggers Voltage-gated calcium (Ca²⁺) channels to open: Ca²⁺ ions to flow INTO axon terminal.
-synaptic vesicles in axon terminal fuse with cell membrane of axon terminal and release NT into synapse
-signal continues to next neuron or target

___________ is when a single neuron sends signals to multiple target neurons, essentially spreading the information.

Divergence

___________ is when multiple neurons send signals to a single neuron, concentrating the information.

convergence
(being bulled by a con! ): )

Sensory (afferent neurons) transmit impulses from _______ to _______

Sensory afferent neurons transmit impulses from PERIPHERAL SENSORY receptors to the CNS

Motor (efferent) neurons transmit impulses from the ______ to _______

Motor (efferent) neurons transmit impulses from the the CNS to an EFFECTOR ORGAN

_______________ are the connection between sensory and motor neurons that transmit impulses from neuron to neuron

interneurons

unipolar neuron

a neuron with one process extending from its cell body

Bipolar neuron

Cell body in the middle with the dendrite on one side and axon on the other

________ neurons are most common

multipolar

_________ neuron has one cell body and MULTIPLE dendrites

multipolar

________ cell body is off to the side. A single process extends from the cell body, which then splits into two branches:
One branch acts like a dendrite, receiving sensory information from the periphery.
The other branch acts like an axon, transmitting the signal toward the CNS

psuedounipolar

______ and _________ neurons are mostly sensory

-bipolar
-psuedounipolar

Neurons generate and conduct ___________

electrical impulses or action potentials

Neurons influence nearby neurons by the release of ________

NTs

An action potential is generated when the ____________________ (the difference in charge between the inside and outside of the neuron) is raised to a certain threshold level.

membrane potential

_______________ is the electrical potential difference (voltage) between the inside and outside of an excitable cell when it is not firing an AP

resting membrane potential

At resting membrane potential, the outside is more _________ (+ or -) relative to the inside

Outside: more positive

Depolarization:

-Making the inside of the cell less negative via influx of Na+

Hyperpolarization:

-Making the inside of the cell more negative (via K+ leaving the cell)

resting membrane potential is due to ____________

the maintenance of the ion conc. gradient by the Na+ potassium pump

___________ is a rapid sequence of changes in the voltage across a membrane

action potential

To generate an AP, the inside of the cell must reach a set voltage aka ____________

threshold potential

In order to generate an AP, we must reach the threshold potential via: depolarization OR hyper polarization

Depolarization: make the inside of the cell less negative

Membrane potential is manipulated by by ______________

changing the flow of ions in/out of the cell through ion channels

Is action potential all-or-none response?

YES, AP only occurs when the stimulus is strong enough, if it is too weak --> the membrane stays unexcited

___________ are regions between adjacent neurons / the junctions where neurons communicate with each other or with other target cells

synapses

Neurons transmit signals across the synapse by two types of conduction:

1. chemical conductions (NT--> most common)
2. electrical conduction (propagation of an electrical signal directly to a cell via gap junction--> cardiac muscle)

____________ allow connections between presynaptic and post synaptic neurons

synapses

In this type of synapse, the axon of the presynaptic neuron forms a connection with the cell body (soma) of the postsynaptic neuron. (axon to cell body)

AXOSOMATIC synapse

The axon of the presynaptic neuron connects to the dendrite of the postsynaptic neuron. (axon to dendrite)

AXODENDRITIC synapse
-most common!

The axon of the presynaptic neuron forms a synapse with the axon of another neuron. (between axons)

AXOAXONIC synapse

The dendrite of one neuron forms a synapse with the dendrite of another neuron. (dendrite to dendrite)

Dendrodendritic synapse

NTs are formed in the _________ and stored in _____________

-cell body of the neuron
-synaptic boutons (vesicles)

If an AP reaches axon terminal, NTs are ____________

released across the synaptic cleft and bind to receptors on the post synaptic neurons (opening or closing ion channels)

Excitatory post synaptic potentials make it (easier or harder) to generate AP

easier

Inhibitory post synaptic potentials make it (easier or harder) to generate AP

harder

When you bring the membrane potential of a neuron closer to threshold, you are ___________ it

depolarizing it, make it less negative (excitatory)

When you bring the membrane potential of a neuron further away from threshold, you are ___________ it

hyper polarizing it, make it more negative (inhibitory)

____________ is the combined effects of multiple inputs at the synapse that determine whether the neuron's membrane potential reaches the threshold to trigger an action potential.

summation

True or false: One release of neurotransmitter (NT) is often not enough to depolarize the postsynaptic neuron to threshold on its own. Therefore, multiple signals need to be integrated for sufficient depolarization.

TRUE baby

________________: occurs when ONE NEURON rapid fires NT. Repeated release of neurotransmitters at short intervals allows --> postsynaptic potential to add up --> inside of the neuron less negative (depolarized)---> increases the likelihood of reaching the threshold for an action potential

Temporal summation

-you can say this one neuron has a short TEMPER....AL

_____________: involves simultaneous signals from multiple neurons ---> increases the likelihood of reaching the threshold for an action potential

Spatial summation

TRUE OR FALSE
Presynaptic neurons CAN make more than one kind of NT

TRUE

Post synaptic neurons have receptors for:
-one kind of NT
-more than one kind of NT

-more than one kind of NT --> allows for modulation

What are the three major divisions of the Brain?

1. Forebrain
2. Midbrain
3. Hindbrain

The forebrain is composed of the ___________

cerebrum and diencephalon

The cerebral cortex is the outer layer of the brain and has ________ control of Bodily functions

contralateral (meaning the left hemisphere controls the right side of the body and vice versa)

Subcortical structures:
-location
-include which 2 important structures

-located under the cerebral cortex and include important structures like the basal ganglia (involved in movement) and the limbic system (involved in emotion and memory).

Gyri (bumps), sulci (grooves), and fissures (deep grooves) ___________________

increase the brain's surface area, allowing for more neurons

The cerebral cortex is made up of ______ matter that is outer and _______ matter that is inner

-Gray matter (nuclei) is outer layer of cerebral cortex
-white matter (myelinated axons/tracts that connect the diff parts of the brain) are the inner layer of cortex

_________ of the cerebral cortex are regions that correlate with specific functions in the brain.

Brodmann's areas

Primary motor cortex is (pre or post) central gyrus

pre-central gyrus

(pre: you MOVE first to reach something)

Primary sensory cortex is (pre or post) central gyrus

post-central gyrus

(post: you FEEL something after you move u reach for it)

prefrontal cortex
-which lobe?
-It controls?

-Frontal lobe
-Controls goal-oriented behavior, reasoning, cognition, personality, short term or recall memory

TIP: Prefrontal cortex = CEO of your brain. It controls planning, thinking, and personality.

primary motor cortex
-location:
-which lobe?
-What does it control?

-precentral gyrus
-frontal lobe
-controls voluntary movement

premotor cortex
-which lobe?
-What does it control?

-frontal lobe
-movement planning and coordinating complex movements

-TIP: Pre-motor = prepares movement

Broca's area
-which lobe?
-What does it control?
-Usually on L or R side

-frontal lobe
-motor aspect of speech
-Usually on L side

primary somatosensory cortex
-which lobe?
-location
-what does it control?

-parietal lobe
-post central gyrus
- processing somatic (sensory) sensation from the body, object identification, spatial relationships, integration of sight smell, touch and information, attention

Primary auditory cortex
-which lobe?
-what does it control?

-temporal lobe
-awareness of sound
-recognition of sound and relating it to memory

Primary olfactory cortex
-which lobe?
-what does it control?

-temporal lobe
-awareness of smell
-recognition of smell and relating it to memory

Wernicke's area
-which lobe?
-what does it control?

-temporal lobe
-reception and interpretation of speech and written language

Deep structures of the temporal lobe are involved in ______ and _________

-long-term memory
-some processing of emotions

Primary visual cortex
-which lobe?
-what does it control?

-occipital lobe
-awareness of vision and recognition and analysis of visual stimuli

__________ connects the two cerebral hemispheres

corpus callosum

True or false: Both the primary motor cortex and the primary somatosensory cortex operate in a contralateral manner.

TRUE

_____________ is involved in processing VISCERAL sensations from the internal organs

insula

Tip: brains INternal sensor of whats happening in organs

____________ of the insula is responsible for balance and spatial awareness

Vesibular cortex of the insula