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67 Cards in this Set

  • Front
  • Back
What are the functional units of the nervous system?
What do neurons do?
Converts stimuli into electrochemical signals that are conducted through the nervous system.
What are the structures of a nuron?
Dendrites - Recieve signal
Soma - Cell Body
Axon - Sends signal on further
What are most neurons insulated with and what does it do?
Myelin sheeths cause the propagation of the signal to go faster
What type of cells produce myelin?
Glial cells
What type of cells produce myelin in the CNS?
What type of cells produce myeling in the PNS?
Schwann cells
What are the gaps between sections of myelin called?
Nodes of ranvier
What is released between neurons and what is this gap called.
Neurotransmitters are released into the synapse
What are action potentials?
Impulses that travel the length of axons.
What is the resting potential?
Potential difference between the extracellular space and the intracellular space

~ -70 millivolts

Inside is more negative
How is the resting potential maintained?
Selective ionic permeability of the neuronal cell membrane and is maintained by the active transport by the Na+/K+ pump (AKA Na+/K+ ATPase)
At resting potential, what are the relative concentration of K+ and Na+ inside and outside the axon?
K+ is higher inside
Na+ is higher outside

Negatively charged proteins are trapped inside the cell.

Created because neuron is selectively permeable to K+, so K+ diffuses down its concentration gradient, leaving a net negative charge.

Neurons are impermeable to Na+.
How is the resting potential restored following polarization?
Gradients must be restored by the Na+/K+ pump.

Uses ATP

Transports 3 Na+ out, for every 2 K+ transports into the cell
How does the action potential begin?
The minimum threshold membrane potential must be achieved (usually around -50 mV)

Nerve cells can receive both excitatory and inhibitory impulses from other cells that bring it closer or farther from the threshold.
After the threshold stimulus has been reached, how is the signal initiated?
Ion channels located in nerve cell membrane open in response to the changes in voltage => voltage gated channels open

Voltage-gated Na+ channels open => Na+ rushes in causing further depolarization.

Na+ channels close, and K+ channels open => K+ rushes down gradient out of the neuron

Returns axon to initial polarization, often passed original value (hyperpolarization)
What is the refractory period?
Period following an initial stimulus in which the neuron can not respond to and initiate a new stimulus.
How is stimulus intensity code in action potentials?
FREQUENCY, not value.

Increased frequency causes in an increase in final output.
What are some important details of Impulse Propagation?
Information transfer can theoretically occur bidirectionally but occurs in only one direction due to refractory period.
What types of neurons can transmit signals the fastest?
Large diameter and heavily myelinated neurons have faster impulses.
What are the neurons before and after the synapse called?
Presynaptic neuron - Neuron before synapse

Postsynaptic neuron - Neuron after synapse
How are neurotransmitters removed from the synapse?
Taken back up into the nerve terminal where it can be reused or degraded

Degraded within the synapse by enzymes (acetylcholinesterase inactivates acetylcholine)

Simple diffusion out of the synapse
What types of drugs can effect the nervous system?
Curane - Blocks post-synaptic acetylcholine receptors so that acetylcholine is unable to interact with the receptor. Lead to paralysis by blocking nerve impulses to muscles.

Botulism Toxin - Prevents release of acetylcholine from presynaptic membrane and results in paralysis.

Anti-cholinesterases - Inhibit the activity of acetylcholinesterase enzyme. Acetylcholine is not degraded and post-synaptic neuron is still effected, with no coordinated motor activity.
Describe the nervous system of the Protozoa?
Unicellular organisms possess no organized nervous system

May responde to touch, heat, light, chemicals
Describe the nervous system of the Cnidaria?
Simple nervous system called a nerve net

Network may have limited coordination

Some jellyfish have clusters of cells and pathways that coordinate the relatively complex movements of swimming
Describe the nervous system of the Annelida?
Earthworms possess a primitive central nervous system consisting of a defined ventral nerve cord, and an anterior "brain" of fused ganglia.

Definite nerve pathways lead from receptors to effectors.
Describe the nervous system of the Arthropoda?
Arthropoda brains are similar to those of annelids, but have more specialized organs present

Compound or simple eyes

Tympanum for detecting sound
What are the three main types of neurons in a vertebrate nervous system?
Afferent Neurons - Sense external or interal environment and send to CNS

Efferent Neurons - Carry motor signals from CNS to the body

Interneurons - participate only in local circuits. linking sensory and motor neurons
What are nerves?
Bundles of axons covered with connective tissue
What is a network of nerve fibers called?
What are clusters of neuronal cell bodies in the PNS called?
What are clusters of neuronal cell bodies in the CNS called?
What are the two major systems of the nervous system called?

Central Nervous System (Brain and Spinal Cord)
What is the nervous system tree diagram?
1) Nervous System
2) Peripheral & Central
3) P - Sensory & Motor
4) M - Somatic & Autonomic
5) A - Sympathetic & Parasympathetic
What are the two components of the central nervous system?
Brain and Spinal Cord
What are the two portions of the brain?
Outer portion called gray matter (cell bodies)

Inner portion called white matter (myelinated axons)
What are the three regions of brain important for the DAT?
Forebrain, Midbrain, Hindbrain
What is within the forebrain?
Telencephalon - Contains cerebral cortex (highly convoluted gray matter that can be seen on surface of brain and is responsible for processing and integrating sensory input and motor responses)

Diencephalon - Contains thalamus (relay and integration center for spinal cord and cerebral cortex) and hypothalamus (controls visceral functions, hunger, thirst, sex drive, water balance, BP, temp regulation and important role in indocrine system control)
What is within the midbrain?
Relay center for visual and auditory impulses

Important role in motor control
What is in the Hindbrain?
Cerebellum, pons, medulla (all constitute the brain stem)

Cerebellum - Modulate motor impulses initiated by cerebral cortex, important in maintenance of balance, hand-eye coordination, timing of rapid movements.

Pons - Relay center to allow cortex to communicate with the cerebellum.

Medulla - Controls breathing, heart rate, GI activity
How does sensory information enter and leave the spinal cord?
Enter (afferent) - Dorsal Horn
Leave (efferent) - Ventral Horn
What is the cross section of the spinal cord look like?
Outer white matter
Inner grey matter
What are the two divisions of the PNS?
Somatic Nervous System

Autonomic Nervous System
What is the somatic nervous system?
Innervates skeletal muscles and is responsible for voluntary movement.
What is the autonomic nervous system?
AKA involuntary nervous system

Regulates body's internal environment

Innervates cardiac and smooth muscle

Two subdivisions:
What is the sympathetic nervous system?
Subgroup of Autonomic Nervous System

Responsible for "flight or fight"

Increased BP, heart rate, and blood flow to skeletal muscles, decreases blood flow to gut.

Dilates bronchioles to increase gas exchange

Norepinephrine is primary neurotransmitter
What is the parasympathetic nervous system?
Subgroup of Autonomic Nervous System

Acts to conserve energy and restore body to resting levels for "rest and digest"

Lower heart rate, increase blood flow to gut.

One very important parasympathetic nerve which innervates many of the thoracic and abdominal viscera is called the vagus nerve and uses acetylcholine as primary neurotransmitter.
How does the eye detect light?
By detecting energy in the form of photons and conveys intensity, color, and shape to brain.
What are the layers of the eye in->out?
Vitreous Humor -> Retina -> Choroid -> Sclera
What is the pathway of light through the eye?
Cornea -> AQ. Humor -> Pupil -> Lens -> Vitreous Humor -> Retina
What is the sclera?
Thick, opaque layer, white
What is the choroid?
Helps supply retina with blood

Dark pigmented to minimize reflection within the eye
What is the retina?
Innermost layer of eye

Contains photoreceptors that sense light
What is the cornea and what does it do?
Transparent at front of eye

Bends and focuses light rays
What is the pupil and how is its size controlled?
Pupil controls the amount of light that enters the eye and is controlled by the muscular/pigmented Iris.
What does the lens do and how is it controlled?
Lens focuses light correctly on the retina by action of the ciliary muscles
What are the two types of photoreceptors within the eye?
Rods - Rhodopsin, black and white, low intensity illumination, single wavelength,

Cones - color, high intensity illumination, 3 wavelengths (red, green, blue)
What is the pathway from retina to brain?
Photoreceptor Cells -> bipolar cells -> ganglion cells -> bundle to form optic nerves -> brain
What is the fovea?
Area of increased acuity on retina
Why is there a blindspot on the eye?
Area where optic nerve leaves eye
Which can be replaced, Aqueous Humor or Vitreous Humor?
Aqueous humor is constantly being secreted and emptied
What is myopia?

image is focused in front of the retina

"my" disease
What is hyperopia?

image is focused behind the retina
What is astigmatism?
Caused by irregular shaped cornea
What are cataracts?
Develop when lens becomes opaque, light cannot enter and blindness results
What is glaucoma?
Increase of pressure in eye due to blocking of the outflow of the Aq. humor
What is the pathway of sound to the brain?
Outer ear -> tympanic membrane -> ossicles (malleus, incus, stapes) -> oval window -> cochlea -> vestibular apparatus -> basilar membrane -> electrical signal -> brain