2025 bio 13 exam 4

Cell body

Contains the nucleus

Dendrites

Short, branching projections. Many clusters, and close to cell body

Axon

Single long projections, can be up to 3 feet long, and arisies from the cell body called the axon hillock

Myelin Sheath

white, fatty, segmented layer that may be on the axon

Axon terminals

Distal tip of the acon, it holds and releases neurotransmitter

Astrocytes

CNS, most abundant and versatile support cells

Microglia

CNA, fixed macrophages - constantly clears dead cells, respond to infections, and maintains brain health

Ependymal Cells

CNS, lines the ventricles, in the spinal cord, produces and regulate CSF

Oligodendrocytes

CNS. Wraps around neurons to form the myelin sheath

Satelite Cells

PNS. Attached to neuron cell bodies, general support cells

Schwann Cells

PNS. Weaps around axons and forms the myelin sheath

Voltage V

Measures the potential energy of seperated charges. Measured in Volts

Current I

Measures the electrical charge from 1 point to another. Measured in amperes

Charges Q

Measures the total number of charged particles by a current. Measured in coulumbs

Ohms Law

V=I x R

Depolarization

Moves voltage toward omV

Hyperpolarization

Moves voltage away from omV

Repolarization

Move voltage back to resting

Group A fibers

Large diameter axon, heavily myelinated, 300 MPH, used by somatic pathways

Group B fibers

Small diameter axon, light myelinated, conducts at 30 mph, autonomic pathways

Group C fibers

Smallest diameter axon, not myelinated, conduct at 2 MPH, autonomic pathways

Electrical synapses

Channels that are similar to gap junctions, no control

Chemical synapses

Uses neurotransmitters,

Presynaptic cell

The neuron before synapse, Axon terminals communice, they send signals

Postsynaptic cell

The neuron after synapse, dendrites connect, they recieve the signal

EPSP

A depolarizing grading potential. Close to -55 mV

IPSP

Huperpolarizing graded potential. Futher away frol -55 mV

Axodendritic synapses

Connects to postsynaptic dendrites

Axosomativ synapses

Connects to postsynaptic cell body

Axonaxonic synapses

Connects to postsynaptic axon hillock

Acetylcholine

Most abundant, alters organ function

Norepinephrine

Alters organ function, pleasure neurotransmitter

Dopamin

Pleasure neurotransmitter

Serotonin

Regulates mood, release is linked to eating. Ecstacy

GABA

Main inhibitory neurotransmitter, opens ligand-gated Cl channels, effects are augments by alcohol

Glutamate

Main excitory neurotransmitter, used for learning and memory

Endorphins

Natural inhibitor of pain, released under stressful conditions

Kinins

Transmit pain signals, released from damaged cells

Ventricles

Filled with CSF, lined with ependymal cells, interconnected

Folding

Increases surface area which means more neurons also meaning high intelligence

Gyrus (gyri)

Eleveated ridge of brakn tissue

Sulcus (sulci)

Shalllow groove in brain tissue

Function areas

Motor, sensory, association areas

Left brain

Math, logic, analytic and language

Right brain

Artisitc, creative, visual, nonverbal, and communication

Primary motor cortex

In frontal lobe, contains pyramidal cells, stimulates skeletal muscles to contract

Mapping

Neurons that control a particular body part are located together

Epilepsy

When Abnormal and excessive electrical discharges is generated in the brain

Petit grand mal

Blank facial expression, facial muscle tics

Grand mal

Body convulsions and loss of consciousness

Premotor cortex

In frontal lobe, used for coordinated movements of several muscle groups

Frontal eye field

Frontal love, aims the eye voluntarily

Brocas area

Frontal lobe, only on the left side, motor area for muslce involved in speech

Primary somatosensory cortex

Parietal lobe, involved with localizing touch

Somatosensory association cortex

Parietal lobe, integrates somatosensory input (touch), recognizing keys in pocket

Primary visual cortex

Occipital lobe, vision is the largest and uses the most energy

Bisual association areas

Occipital lobe, allows us to use past visual experiences to identify

Primary auditory cortex

Temporal lobe, converts actipn potential from east to south

Auditory association area

Temporal lobe, associates currenr sound with known sounds

Gustatory area

Insula, taste

Olfactory area

Temporal, smell

Vestibular cortex

Insula sense of balance

Visceral sensory

insula, crude perception of organ discomfort

Somatic sensory

Conscious information from skin and muscles

Somatic motor

Conscious commands

Autonomic motor

Subconscious commands

Nervous tissue

High rate of metabolism, poor capacity for repair, highly cellular

Neurons

Also called neurocytes, nerve cells, functional unit of the nervous system, long and thin projections, human body contains 10^12 neurons

Na+ Ion movement

Out of the cell, 3 of these are expelled from the cell

K+ ion movement

Into the cell, 2 of these are brought into the cell

Membrane potential at rest

-70 mV, active transport and selective permability

Action potential

A brief reversal of membrane potential woth a total amplitude of about 100 mV

Absolutely refractory period

Begins with opening of the Na channels and ends when the Na channels begin to reset

Relative refractory period

Most Na channels are still open and repolarization is occuring

ATPase pump

It helps restore the original ion gradients after action potential ends

Graded potential

It can have amplitudes of various sizes

Subthreshold potential

Very weak EPSP

Temporal summation

Use more at the same time

Spatial summation

Use the same repeatedly

Lateral ventricle

Largest ventrical, located deep to cerebral hemisphere

Cerebral cortex

Gray matter, located outer layer od the cerebral hemisphere

Cerebral white matter

White, located beneath the cortex

Basal nuclei

Gray, deep within the white matter of the cerebral hemisphere

Contralateral

Refers to the opposite side of the body

Ipislateral

Refers to the same side of the body

Pyramidal neuron

To send long range signals in the brain and spinal

Voltage- gated sodium channels

Channel opens due to a change on local charge disturbance, high conductance

Ligand-gated channels

A small chemical that comes and binds, opens when a particular chemical binds to it, low conductance

Leak channel

Always open, low conductance, mostly K+ to pass

Mechanically-gated channels

Channels opens in response to a physical stimulus

Third ventricle

Thin channel deep to diencephalon

Fourth ventricle

Diamond-shaped deep to brain stem, connects to central canal cord

Efferent

Information from the CNS to muscle groups

Afferent

Information from the CNS to the skin, muscle and body organs