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Flashcards in Nervous System Deck (49):
1

What are neuroglia cells?

-AKA glial cells
-Secrete myelin
-Supply oxygen and nutrients to neurons
-Protect and support neurons

2

What are the components of a neuron?

-Dendrite, cell body, axon

3

Dendrites...

...are cytoplasmic extensions that receive information and transmit to cell body.

4

Axons...

...transmit action potentials away from the cell body.
-Mostly sheathed by myelin
-End in synaptic terminal

5

What is the purpose of mylein sheath?

-Prevent leakage of signal from axon
-Faster conduction of signal

6

Nodes of Ranvier...

...gaps between myelin sheath.
-Signal propagates by saltutory conduction

7

Oligodendrocytes...

-Type of glial cells
-Produce myelin in CNS

8

What type of cell produces myelin in the PNS?

-Schwann cells

9

Where are neurotransmitters released?

-From axon terminals into synapse to an adjacent dendrite

10

What are astrocytes?

-In CNS
-Maintain integrity of blood-brain barrier
-Regulate nutrient and dissolved gas conc
-Absorb/recycle neurotransmitters

11

What are microglia?

-In CNS
-Remove cell debris and pathogens

12

What are ependymal cells?

-Line brain ventricles
-Make/maintain cerebral fluid

13

What are satellite cells?

-In PNS
-Surround neuron cell bodies in ganglia (autonomic nervous system)

14

What is the resting potential of a neuron?

-Polarized (-70mV)
-Maintained by Na+/K+ pump
-Membrane more permeable to K+, diffuse back out

15

Describe the transmission of action potentials.

-Causes depolarization (more positive inside cell)
-Reach threshold potential
-Na+ to flow down gradient --> depolarize more of axon
-Reach synaptic terminal --> Ca++ flow in
-Exocytosis of synaptic vesicles with neurotransmitters

16

Describe repolarization.

-High voltage causes K+ channels to open
-K+ rush down gradient and out of cell
-Voltage gated Na+ channel closes
-Na+/K+ begins again

17

Describe hyperpolarization.

-Repolarized past resting potential due to K+ still being permeable
-Allows time for regeneration of neurotransmitters
-Potential only moves forward
-Refractory period

18

What is the stimulus intensity coded by?

-Frequency NOT magnitude of action potential

19

What are factors that allow faster propagation of stimuls?

-More myelinated (only permeable to ions in Nodes of Ranvier)
-Larger diameter of axon

20

What are the ways neurotransmitters are removed from the synapse?

-Taken back up into the nerve terminal (reused/degraded)
-Degraded by enzymes in synapse
-Diffuse out of synapse

21

What are afferent neurons?

-Carry sensory information from external/internal environment to brain/spinal cord

22

What are efferent neurons?

-Carry motor commands from brain/spinal cord to body

23

What are interneurons?

-Participate only in local circuits
-Linking sensory and motor neurons

24

Organization of nerves

-Bundle of axons covered with connective tissue (nerves)
-Nerve fibers = plexus
-Neuronal cell body clusters = ganglia(PNS) or nuclei (CNS)

25

What is the difference between gray and white matter?

-Gray matter is outer portion of cell bodies
-White matter is inner portion of myelinated axons

26

Forebrain

-Telencephalon and diencephalon

27

Telencephalon

-Cerebral cortex process/integrate sensory/motor
-Memory/Creative thought
-Olfactory bulb

28

Diencephalon

-Thalamus integrate spinal cord and cerebral cortex
-Hypothalamus controls visceral functions (hunger/thirst/sex/temp)

29

Midbrain

-Relay center for visual and auditory impulses
-Motor control

30

Hindbrain

-Cerebellum, the pons, medulla

31

Cerebellum

-Balance, hand-eye coordination, modulate motor impulses by cerebral cortex

32

Pons

-Relay center to allow cortex to communicate with cerebellum

33

Medulla

-Vital functions (breathing, HR, GI)

34

What makes up the brainstem?

-Midbrain, pons, medulla

35

Spinal Cord

-Outer white matter, inner gray
-Can integrate motor responses itself

36

How does sensory information enter spinal cord?

-Through the dorsal horn (dorsal root ganglia) and exits ventral horn

37

What does the PNS consist of?

-Somatic and Autonomic

38

Somatic Nervous System

-Innervate skeletal muscles
-Voluntary movement and reflex arcs

39

Autonomic Nervous System

-Involuntary - cardiac and smooth muscles
-Sympathetic and parasympathetic

40

Where is smooth muscles located?

-Blood vessels, digestive tract, bladder, bronchi

41

Sympathetic Nervous System

-"Fight or Flight"
-Increase bp, HR, blood flow to skeletal muscle
-Decrease gut motility
-Dilate bronchioles to increase gas exchange
-Norepinephrine

42

What is the primary neurotransmitter for sympathetic nervous system? Parasympathetic?

-Norepinephrine
-Acetylcholine

43

Parasympathetic Nervous System

-"Rest and digest"
-Lowers hr, increase digestion
-Vagus nerve - innervate thoracic and abdominal viscera
-Acetylcholine

44

What bends and focuses light?

-Cornea

45

What controls the diameter of the pupil?

-Iris by responding to intensity of light

46

Lens...

...focuses image onto retina.

47

Describe the synaptic pathway of photoreceptors.

Synapse onto bipolar cells --> ganglion cells --> optic nerve --> brain

48

What causes action potentials to transmit to brain in hearing?

-Ossicles vibrate and exert pressure on inner ear fluid which stimulates hair cells in basilar membrane
-Pressure --> action potential

49

Motor unit

-All muscle fibers innervated by one nerve fiber