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Anatomy and Physiology > Chapter 12 Central Nervous System > Flashcards

Chapter 12 Central Nervous System Flashcards

1
Q

The nervous system

A

Brain and spinal cord
Receptors of sense organs (eyes, ears, etc.)
Nerves that connect to other systems

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2
Q

Nervous tissue contains two kinds of cells

A

Neurons for intercellular communication
Neuroglia (glial cells)

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3
Q

Neuroglia (glial cells)

A

Essential to survival and function of neurons
Preserve structure of nervous tissue

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4
Q

Anatomical divisions of the nervous system

A

Central nervous system
Peripheral nervous system

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5
Q

Central nervous system (CNS)

A

Brain and spinal cord
Consists of nervous tissue, connective tissue, and blood vessels
Functions to process and coordinate sensory data from inside and outside body
Motor commands control activities of peripheral organs (e.g., skeletal muscles)
Higher functions of brain include intelligence, memory, learning, and emotion

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6
Q

Special Sensory Receptors Path

A

Smell, Taste, Vision, Balance, Hearing - to Afferent Div of the PNS then to brain (CNS)

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7
Q

Visceral Sensory Receptors Path

A

Monitors internal organs, to Afferent Div of the PNS then to brain

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8
Q

Somatic Sensory Receptors Path

A

Skeletal, Muscle, Joints, Skin to Afferent Div of PNS and then to brain

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9
Q

From Brain (CNS) to Skeletal Syst

A

Brain to Motor Command then to Somatic Nervous Syst (SNS), to Skeletal syst.

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10
Q

From Brain to Parasympathetic System

A

Brain, Motor Commands, Autonomic Nervous Syst (ANS), Parasympathetic Syst to Smooth Muscle, Cardiac Muscle and Glands

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11
Q

From Brain to Sympathetic Nervous Syst

A

Brain, Motor Commands, Autonomic Nervous Syst (ANS), Sympathetic Syst. to Smooth Muscle, Cardiac Muscle, Glands and Adipose Tissue

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12
Q

Neurons

A

Basic functional units of the nervous system
Send and receive signals
Function in communication, information processing, and control

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13
Q

Cell body (soma)

A

Large nucleus and nucleolus
Perikaryon (cytoplasm)
Mitochondria (produce energy)
RER (Rough Endoplasmic Reticulum) and ribosomes (synthesize proteins)

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14
Q

Cytoskeleton of perikaryon

A

Neurofilaments and neurotubules
Similar to intermediate filaments and microtubules
Neurofibrils
Bundles of neurofilaments that provide support for dendrites and axon

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15
Q

Nissl bodies

A

Dense areas of RER and ribosomes in perikaryon
Make nervous tissue appear gray (gray matter)

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16
Q

Dendrites

A

Short and highly branched processes extending from cell body

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17
Q

Dendritic spines

A

Fine processes on dendrites
Receive information from other neurons
80–90 percent of neuron surface area

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18
Q

Axon

A

Single, long cytoplasmic process
Propagates electrical signals (action potentials)

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19
Q

Axoplasm

A

Cytoplasm of axon
Contains neurofibrils, neurotubules, enzymes, and organelles

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20
Q

Structures of the axon

A

Axolemma - Plasma membrane of the axon and Covers the axoplasm

Initial segment - Base of axon

Axon hillock - Thick region that attaches initial segment to cell body

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21
Q

Structures of the axon pt 2

A

Collaterals
Branches of the axon
Telodendria
Fine extensions of distal axon
Axon terminals (synaptic terminals)
Tips of telodendria

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22
Q

Neurons - Axonal (axoplasmic) transport

A

Movement of materials between cell body and axon terminals
Materials move along neurotubules within axon
Powered by mitochondria, kinesin, and dynein

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23
Q

Structural classification of neurons

A

Anaxonic neurons - May have more than 2 processes
Small and may all be Dendrites
All cell processes look similar, Axons not Obvious
Found in brain and special sense organs
Bipolar neurons - 2 processes, Seperated by Cell Body
Small and rare
One dendrite and one axon
Found in special sense organs (sight, smell, hearing)

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24
Q

Structural classification of neurons pt 2

A

Unipolar neurons (pseudounipolar neurons)
Single Elongated Process off to the side
Axon and dendrites are fused
Cell body to one side
Most sensory neurons of PNS
Multipolar neurons - have more than 2 processes
Has single long axon and multiple dendrites
Common in the CNS
All motor neurons that control skeletal muscles

25
Q

Sensory neurons (afferent neurons)

A

Unipolar
Cell bodies grouped in sensory ganglia
Processes (afferent fibers) extend from sensory receptors to CNS

26
Q

Somatic sensory neurons

A

Monitor external environment

27
Q

Visceral sensory neurons

A

Monitor internal environment

28
Q

Ganglia

A

Nerve cell cluster or a group of nerve cell bodies located in the autonomic nervous system and sensory system
ganglia house the cells bodies of afferent nerves and efferent nerves

29
Q

Types of sensory receptors

A

Interoceptors
Monitor internal systems (e.g., digestive, urinary)
Internal senses (stretch, deep pressure, pain)
Exteroceptors
Monitor external environment (e.g., temperature)
Complex senses (e.g., sight, smell, hearing)
Proprioceptors
Monitor position and movement of skeletal muscles and joints

30
Q

Types of sensory receptors pt 2

A

Proprioceptors (cont)
Carry instructions from CNS to peripheral effectors
Via efferent fibers (axons)
Somatic motor neurons of SNS
Innervate skeletal muscles
Visceral motor neurons of ANS
Innervate all other peripheral effectors
Smooth and cardiac muscle, glands, adipose tissue

31
Q

Motor neurons

A

Signals from CNS to visceral effectors cross autonomic ganglia that divide axons into
Preganglionic fibers
Postganglionic fibers

32
Q

Interneurons

A

Most are in brain and spinal cord
Some in autonomic ganglia
Located between sensory and motor neurons
Responsible for
Distribution of sensory information
Coordination of motor activity
Involved in higher functions
Memory, planning, learning

33
Q

Neuroglia

A

Support and protect neurons
Make up half the volume of the nervous system
Many types in CNS and PNS

34
Q

Neuroglia

A

Types of NEUROGLIA
Astrocytes
Ependymal
Oligodendrites
Microgila

35
Q

Astrocytes (Brain) Star Shaped, anchor to capillaries

A

Blood Brain Barrier, structural support, regulate ion, neutrient, gas concentrations, absorb recycle neurotransmitters, scar tissue after injury
Have large cell bodies with many processes
Function to
Maintain blood brain barrier (BBB)
Create three-dimensional framework for CNS
Repair damaged nervous tissue
Guide neuron development
Control interstitial environment

36
Q

Ependymals (Brain) - simple cuboidal epithelial cells that line fluid-
filled passageways within the brain and spinal
cord

A

line the ventricles + central canal (spinal cord), assist with cerebrospinal fluid
Form epithelium that lines central canal of spinal cord and ventricles of brain
Produce and monitor cerebrospinal fluid (CSF)
Have cilia that help circulate CSF

37
Q

Oligodendrites (Brain)

A

structural framework, myelinate sheet like process that surrounds CNS Axons, increases speed of action potentials. Nerves appear white.
Internodes—myelinated segments of axon
Nodes (nodes of Ranvier) lie between internodes
Where axons may branch
White matter
Regions of CNS with many myelinated axons
Gray matter of CNS
Contains unmyelinated axons, neuron cell bodies, and dendrites

38
Q

Microgila (Brain) - are phagocytes

A

Smallest and least numerous neuroglia
Have many fine-branched processes
Migrate through nervous tissue
Clean up cellular debris, wastes, and pathogens by phagocytosis

39
Q

Neural responses to injuries

A

Wallerian degeneration
Axon distal to injury degenerates
Schwann cells
Form path for new growth
Wrap around new axon

40
Q

Nerve regeneration in CNS

A

Limited by astrocytes, which
Produce scar tissue
Release chemicals that block regrowth

41
Q

All plasma (cell) membranes produce electrical signals by ion movements

A

Membrane potential is particularly important to neurons

42
Q

Resting membrane potential

A

Three important concepts
The extracellular fluid (ECF) and intracellular
fluid (cytosol) differ greatly in ionic composition
Extracellular fluid contains high concentrations of Na+ and
Cl–
Cytosol contains high concentrations of K+ and negatively
charged proteins
Cells have selectively permeable membranes
Membrane permeability varies by ion

43
Q

Graded potential

A

Temporary, localized change in resting potential
Caused by a stimulus

44
Q

Action potential (nerve impulses)
All-or-none principle
Any stimulus that changes the membrane potential to threshold
Will cause an action potential
All action potentials are the same
No matter how large the stimulus
An action potential is either triggered or not

A

Is an electrical impulse
Produced by graded potential
Propagates along surface of axon to synapse
Propagated changes in membrane potential
Affect an entire excitable membrane
Begin at initial segment of axon
Do not diminish as they move away from source
Stimulated by a graded potential that depolarizes the axolemma to threshold
Threshold for an axon is –60 to –55 mV

45
Q

Passive processes acting across cell membrane

A

Current
Movement of charges to eliminate a potential difference
Resistance
How much the membrane restricts ion movement
If resistance is high, current is small

46
Q

Passive processes acting across cell membrane

A

Chemical gradients
Concentration gradients of ions (Na+, K+)
Electrical gradients
Charges are separated by cell membrane
Cytosol is negative relative to extracellular fluid

47
Q

Electrochemical gradient

A

Sum of chemical and electrical forces acting on an ion across the membrane
A form of potential energy

48
Q

Equilibrium potential

A

Membrane potential at which there is no net movement of a particular ion across cell membrane
K+ = –90 mV
Na+ = +66 mV
Plasma membrane is highly permeable to K+
Explains similarity of equilibrium potential for K+ and resting membrane potential (–70 mV)
Resting membrane’s permeability to Na+ is very low
So Na+ has a small effect on resting potential

49
Q

Resting membrane potential exists because:
Cytosol differs from extracellular fluid in chemical and ionic composition
Plasma membrane is selectively permeable

A

Membrane potential changes in response to temporary changes in membrane permeability
Results from opening or closing of specific membrane channels
In response to stimuli

50
Q

Na+ and K+ are the primary determinants of membrane potential

A

Passive ion channels (leak channels)
Are always open
Permeability changes with conditions
Active ion channels (gated ion channels)
Open and close in response to stimuli
At resting membrane potential, most are closed

51
Q

Chemically Gated Ion Channel - (Active Channel)

A

Called Ligand - Gated Ion Channel.
Opens when it binds to specific Chems (ie ACh)
Found on cell bodies and dendrites of neurons

52
Q

Voltage-gated ion channels

A

Respond to changes in membrane potential
Found in axons of neurons and sarcolemma of skeletal and cardiac muscle cells
Activation gate opens when stimulated
Inactivation gate closes to stop ion movement
Three possible states
Closed but capable of opening
Open (activated)
Closed and incapable of opening (inactivated)

53
Q

Mechanically gated ion channels

A

Respond to membrane distortion
Found in sensory receptors that respond to touch, pressure, or vibration

54
Q

Graded potentials (local potentials) -
Characteristics
Membrane potential is most changed at site of stimulation; effect
decreases with distance
Effect spreads passively, due to local currents
Graded change in membrane potential may involve depolarization
or hyperpolarization
Stronger stimuli produce greater changes in membrane potential
and affect a larger area

A

Changes in membrane potential
That cannot spread far from site of stimulation
Produced by any stimulus that opens gated channels
Example: a resting membrane is exposed to a chemical
Chemically gated Na+ channels open
Sodium ions enter cell
Membrane potential rises (depolarization)

55
Q

Graded potentials - Repolarization
When the stimulus is removed,
membrane potential returns to normal
Hyperpolarization
Results from opening potassium ion channels
Positive ions move out, not into cell
Opposite effect of opening sodium ion
channels
Increases the negativity of the resting potential

A

Sodium ions move parallel to plasma membrane
Producing local current
Which depolarizes nearby regions of plasma membrane (graded
potential)
Change in potential is proportional to stimulus
Often trigger specific cell functions
Example: exocytosis of glandular secretions
ACh causes graded potential at motor end plate at neuromuscular junction

56
Q

Resting membrane with closed chemically gated sodium ion channels

A

-70mv

57
Q

Membrane exposed to chemical that opens the sodium ion channels

A

-65mv

58
Q

Generation of action potentials
Step 1: Depolarization to threshold
Step 2: Activation of voltage-gated Na channels
Na+ rushes into cytosol
Inner membrane surface changes from negative to positive
Results in rapid depolarization

A

Generation of action potentials
Step 3: Inactivation of Na channels and activation of K+ channels
At +30 mV, inactivation gates of voltage-gated Na+ channels close
Voltage-gated K+ channels open
K+ moves out of cytosol
Repolarization begins

59
Q
A

Anatomy and Physiology (15 decks)

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