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4a Introducing The Nervous System Flashcards

1
Q

What is the nervous system?

A

A body system that integrates and generates appropriate rapid responses to maintain homeostasis

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2
Q

What are the functions of the nervous system?

A

Sensory input: detecting changes (stimuli) occurring inside and outside the body
Integration: processes and interprets sensory input and determines course of action
Motor output: a response or effect that activates muscles or glands
SIM

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3
Q

What kind of stimuli could be considered sensory input?

A

Changes in: pressure, light, taste, blood pH, sound and hormone levels
Basically anything detected by the 5 senses

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4
Q

What kind of response can be considered a motor output?

A

Movement
Changes in heart rate
Release of hormones
Sweating
Release/storage of glucose

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5
Q

What is a motor output caused by?

A

Caused by an electrochemical signal transmitted to organs from the CNS that is converted into some form of action
Nerve fibers that carry impulses away from CNS organs to effector organs

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6
Q

What components are the nervous system divided into? Be specific.

A

Structural:
-Central Nervous System: brain and spinal cord
-Peripheral Nervous System: cranial and spinal nerves

Functional:
Parasympathetic and sympathetic systems

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7
Q

What type of motor outputs are there?

A

Somatic: voluntary
Autonomic: involuntary

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8
Q

What do cranial and spinal nerves do?

A

Carry nerve impulses to and from the brain and spinal cord respectively

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9
Q

What is the function of the CNS vs the PNS?

A

CNS: integration (command center), interprets incoming sensory information, issues outgoing instructions
PNS: serves as communication lines among sensory organs, the brain and spinal cord, and glands or muscles

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10
Q

What are the two sensory divisions? Are they afférent or efferent?

A

Both afferent
Somatic sensory: fibers carry info from skin, skeletal muscles and joints
Visceral sensory: fibers carry info from visceral organs

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11
Q

What are the two motor divisions? Are they afferent or efferent?

A

Both efferent
Somatic nervous system: conscious or voluntary, controls skeletal muscles
Autonomic nervous system: automatic or involuntary, controls smooth and cardiac muscles and glands

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12
Q

What is the autonomic nervous system further divided into?

A

Sympathetic (fight or flight) and Parasympathetic (rest and digest)

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13
Q

Describe the path a stimulus would take to elicit a response from the body.

A
  1. Sensory organs detect the stimulus
  2. Sensory receptors send the information to the CNS (command center) via the nerves of the PNS
  3. The CNS integrates and processes the information, decides the appropriate response
  4. CNS sends a motor signal through the PNS to either a component of the parasympathetic or sympathetic nervous system
  5. If a quick reaction is required, it’ll be the sympathetic nervous system
    - if it is not required, it’ll be the parasympathetic nervous system
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14
Q

What are the types of nerve cells/tissues? Describe.

A

Neuroglia: supporting cells, providing structural support, protection, growth factors and insulating sheaths
Neurons: excitable cells that generate and transmit nerve impulses

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15
Q

What is a nerve impulse?

A

An electrochemical signal or message

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16
Q

What is the ratio of Neuroglia to neurons?

A

10:1

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17
Q

What are the types of Neuroglia (CNS)?

A

-Astrocytes
-Microglial cells
-Ependymal cells
-Oligodendrocytes

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18
Q

Shape of astrocytes? Function?

A

Abundant, star shaped
Function:
-Brace and anchor neurons to blood capillaries
-Absorb excess k+ and neurotransmitter released from neurons
-Mediate exchanges between blood capillaries and neurons
-Provides nutrients to neurons
(BAMP)

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19
Q

What are microglial cells? Function?

A

Phagocytes that defend CNS cells
Monitor health of nearby neurons
Engulf debris (dead brain cells) and bacteria (défense)

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20
Q

What are ependymal cells? Function?

A

Line cerebrospinal fluid-filled cavities (brain and spinal cord)
Produce cerebrospinal fluid
Ciliated: cilia assist with circulation of cerebrospinal fluid

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21
Q

What is CSF?

A

Cerebrospinal fluid
For protection, regulation of blood pressure and chemical transport for brain
Derived from blood plasma so many of the same constituents as blood

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22
Q

What are oligodendrocytes? Function?

A

Produce myelin sheaths to wrap around multiple nerve fibers

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23
Q

What is the purpose/function of myelin sheaths?

A

Speed up conduction of nerve impulses

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24
Q

What are the types of Neuroglia in the PNS?

A

Satellite cells and Schwann cells

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25
What do satellite cells do?
Protective cushioning of neuron cell bodies, literally a cushy blanket cocoon
26
What do Schwann cells do?
Produce myelin sheaths around nerve fibers
27
What are the differences and similarities between schwann cells and oligodendrocytes?
Schwann cells wrap around one axon, its protection is limited and localized to that axon Oligodendrocytes wrap around multiple axons Both produce myelin sheaths and speed up signaling
28
What are neurons? Characteristics and functions?
Functional unit of nervous system High metabolic rate, requires continuous supply of O2 and glucose Generates and conducts nerve impulses Results in excitation or inhibition of neighbouring neuron, muscle or gland
29
What is the structure of a neuron?
Cell body: metabolic center, has organelles, neurofibrils for cell shape but no centrioles Dendrites: fibers conducting impulses toward the cell body, a single neuron may have hundreds of dendrites Axon: fibre conducts impulse away from cell body, a neuron has only 1 axon
30
Why do neurons, specifically the cell body, not have centrioles?
Because they are non-mitotic (will not divide)
31
Where does the axon of the neuron begin? End? Whats in between?
Begin: axon hillock (little tail from cell body leading to axon, before the myelin sheath) End: axon terminals, contain neurotransmitters Between the end of a neuron and the beginning of the next: synapse or synaptic cleft
32
What is a myelin sheath?
A white fatty material that covers most of the axons in the PNS and some in the CNS
33
What is an axon covered in myelin sheaths called?
Myelinated axons
34
What type of cells form myelin sheaths in the CNS? PNS?
CNS: Oligodendrocytes PNS: Schwann cells
35
Describe myelin sheath formation in Schwann cells and oligodendrocytes.
Schwann Schwann cell rolls around the axon at the same spot in layers The cytoplasm and nucleus are forced to the outer region of the cell (external to the sheath) called the neurilemma Oligodendrocytes Same as Schwann process except there is no neurilemma
36
Why is there no neurilemma in the myelin sheaths in the CNS? Consequences?
Myelin sheaths in the CNS are formed by oligodendrocytes which do not fully wrap around the axon but rather their extensions do, so the nucleus and cytoplasm doesnt wrap as in Schwann cells Consequence: the axons and myelin sheaths in the CNS are not capable of regeneration, but those in the PNS are to some extent
37
What is the function of myelin sheaths?
To protect the axon Ions cannot enter or exit the axon in regions surrounded by myelin -This provides electrical insulation that increases the rate of conduction of a nerve impulse (faster communication)
38
What are the gaps between schwann cells called and what is their purpose?
Nodes of Ranvier To allow Saltatory conduction
39
What is saltatory conduction?
The transmission of electrical signals by “jumping” from gap to gap to increase the speed of conduction
40
What is MS?
Multiple Sclerosis An autoimmune disease in which the myelin sheaths in the brain and spinal cord are progressively destroyed in a process called demyelination The scars (scleroses) slow the transmission of nerve impulses and eventually stop the transmission altogether
41
What are the consequences of MS? Treatment?
Can result in paralysis and loss of sensation Loss of vision Affects primarily young adults Treatment: drugs that modify immune system
42
What differentiates the different structural classifications of neurons and what are they?
The number of processes that extend from the cell body Multipolar: multiple processes Bipolar: 2 processes extending from body Unipolar: only one process extending from cell body into dendrites
43
Where can you find multipolar neurons?
In motorneurons and interneurons
44
Where can you find bipolar neurons?
Special sense organs (nose, eyes, ear) Special note: rare in adults
45
Characteristic of unipolar neurons?
Majority of sensory neurons
46
What are the functional classifications of neurons?
Sensory neurons Interneurons Motor neuron
47
What does the sensory neuron do and is it afférent or efferent?
Afférent Carries impulse from sensory receptors to CNS Note: all receptors, dendrites and cell bodies are located in PNS, only axons are occasionally in the CNS
48
What does the motor neuron do and is it efferent or afférent?
Efferent Carries impulses from CNS to visceral, muscles and glands Note: dendrites and cell body located in CNS (to talk to interneurons)
49
What do the interneurons do and what are they also known as?
Association neurons Connect sensory and motor neurons Cell bodies located in the CNS, whole thing
50
What are sensory receptors and what are the types?
Specialized receptors formed by dendritic ends of sensory neurons Cutaneous receptors and proprioreceptors
51
Where are cutaneous receptors located?
Located in skin (touch, pain, temperature, pressure)
52
Where are proprioreceptors located?
Located in muscles and tendons (stretching and tension)
53
How many motor and inter neurons are there typically?
Interneuron: 1-3 Motor neuron: 1-2
54
What words are used to describe clusters of cell bodies in both the CNS and PNS?
CNS: nuclei PNS: ganglia
55
What words are used to describe the bundles of fibres running together in the PNS and CNS?
CNS: tract PNS: nerve
56
What words are used to describe large area of nuclei (and unmyelinated axons) in the CNS and PNS?
CNS: gray matter PNS: no term
57
What words are used to describe large areas of tracts in the CNS and PNS?
CNS: White matter PNS: no term
58
Describe the organization of a nerve from small to big.
Endoneurium: connective tissue sheath that surrounds each myelinated axon Perineurium: wraps around groups of fibres (endoneuriums) bound into a fascicle Epineurium: binds groups of fascicles
59
What is a mixed nerve?
A nerve that contains both sensory and motor fibres Ex: spinal cord contains mixed nerves
60
Differentiate gray matter from white matter.
Gray: unmyelinated, mainly cell bodies and dendrites, very little axon White: shiny, white, has myelin

Anatomy (19 decks)

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