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BIO 181-171 > CH 13: 10-04-13 (BIO 181) > Flashcards

CH 13: 10-04-13 (BIO 181) Flashcards

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Biology 101 flashcards
1
Q
  • Rapid, automatic nerve responses triggered by specific stimuli
  • Controlled by spinal cord alone, not the brain
A

• Spinal Reflexes

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2
Q
  • Ends between vertebrae L1 and L2
  • Bilaterally symmetrical and is divided into left and right by grooves
  • Posterior median sulcus: on posterior (dorsal) side
  • Anterior median fissure: on anterior (ventral) side
  • Enlargements of the Spinal Cord
  • Are seen at regions that are involved with the sensory/motor control of the limbs
  • These expanded regions have more gray matter per segment than other regions
  • Cervical enlargement
  • Provides innervation to shoulders and upper limbs
  • Lumbar enlargement
  • Provides innervation to pelvis and lower limbs
  • Total of 31 Spinal Cord Segments
  • Nomenclature is based on vertebrae where spinal nerves originate
A

Spinal Cord

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3
Q
  • Specialized membranes that isolate spinal cord from surroundings and is continuous with cranial meninges
  • Functions of the spinal meninges include
  • Protect spinal cord
  • Carry blood supply
A

Spinal Meninges

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4
Q

• Viral or bacterial infection of meninges

A

• Meningitis:

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5
Q

• Outer layer of spinal cord

A

dura mater

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6
Q

middle meningeal layer

A

arachnoid mater

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7
Q

inner meningeal layer

A

pia mater

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8
Q
  • Between spinal dura mater and walls of vertebral canal
  • Contains loose connective and adipose tissue
  • Represents the anesthetic injection site
A

• Epidural Space

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9
Q
  • Between arachnoid mater and pia mater
  • Contains a network of collagen/elastin fibers
  • Filled with cerebrospinal fluid (CSF)
  • Represents site of Spinal tap (withdrawal of CSF from lumbar region)
A

• Subarachnoid space

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10
Q
  • posterior
  • For sensory functions
  • contain sensory nuclei that connect to peripheral receptors
A

dorsal spinal segment

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11
Q
  • anterior
  • For motor functions
  • contain motor nuclei that connect to peripheral effectors
A

ventral spinal segment

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12
Q
  • Carries information from place to place

* Contains primarily myelinated axons (and less unmyelinated axons)

A

• White Matter (outer region)

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13
Q
  • Region of integration and motor command initiation
  • Contains neuron cell bodies, neuroglia, unmyelinated axons
  • Has projections (gray horns)
A

• Gray Matter (inner region)

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14
Q
  • Posterior (dorsal) gray horns contain somatic and visceral sensory nuclei
  • Anterior (ventral) gray horns contain somatic motor nuclei
  • Lateral gray horns: are in thoracic and lumbar segments; contain visceral motor nuclei
A

• Organization of gray horns

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15
Q

• Axons that cross from one side of cord to the other before reaching a particular destination in the gray matter

A

• Gray commissures

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16
Q
  • afferent fibers originate at sensory receptors in the skin and project to the dorsal horn (one on each side) of the gray matter
  • Cell bodies of afferent fibers are located outside of the spinal cord – in the Dorsal Root Ganglia
A

gray matter• Dorsal: (posterior)sensory functions (afferent fibers)

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17
Q
  • efferent fibers travel from the ventral horn (one on each side) of the gray matter to the target muscle
  • Cell bodies of efferent fibers are located within the spinal cord
A

gray matter• Ventral: (anterior) motor functions (efferent fibers)

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18
Q
  • Both the afferent and efferent fibers come together to form the spinal nerve (not too far away from the spinal cord)
  • Thus, all spinal nerves are___
A

mixed

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19
Q

consist of bilateral fiber tracts that transmit information between the brain and spinal cord

A

white matter

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20
Q

from the spinal cord to the brain

A

ascending tracts

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21
Q

from the brain to the spinal cord

A

descending tracts

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22
Q

___ and ___Tracts are made up of axon bundles called Tracts or fasciculi

A

ascending and descending

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23
Q

• between posterior gray horns and posterior median sulcus

A

• Posterior white columns in white matter

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24
Q
  • lie between anterior gray horns and anterior median fissure
  • Anterior white commissure: area where axons cross from one side of spinal cord to the other
A

• Anterior white columns in white matter

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25
Q

• located on each side of spinal cord between anterior and posterior columns

A

• Lateral white columns in white matter

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26
Q
  • Originate in sensory touch receptors in the skin
  • Communicate sensory information to the thalamus
  • Terminate in the somatosensory cortex
A

dorsal columns ascending tracts

27
Q
  • Originate in the primary motor cortex

* Terminate in the ventral horn of the spinal cord and communicate to motor neurons of skeletal muscle

A

Descending Tracts - Example

• Pyramidal Tracts

28
Q
  • Fibers originating in the dorsal and ventral horns are called dorsal and ventral roots, respectively.
  • Dorsal and ventral roots join to form a spinal nerve
  • Each spinal nerve divides into a dorsal and ventral ramus
A

spinal nerves

29
Q

___rami innervate the skin and muscles of the back

A

dorsal

30
Q

____rami innervate the limbs and the rest of the trunk

A

ventral

31
Q
  • From the spinal cord, axons of spinal nerves must enter Sympathetic Ganglion at the Sympathetic Chain (outside of spinal cord)
  • At sympathetic ganglion, these preganglionic neurons synapse onto postganglionic neurons, which then go to effector organs
  • As the spinal nerves extend into the periphery, they branch out to form the PERIPHERAL NERVES that ultimately innervate the body tissues and organs.
  • Therefore, peripheral nerves are interconnecting branches of spinal nerves that form at the region where the dorsal (sensory) and ventral (motor) roots unite
  • Thus, peripheral nerves are made up of motor AND sensory fibers
  • Each pair of spinal nerves innervates a SPECIFIC region of skin on the body
  • Therefore, it is possible to MAP OUT the body’s surface into different sensory regions called Dermatomes
A

Peripheral Distribution of Spinal Nerves

32
Q

• Bilateral region of skin that is innervated or monitored by specific pair of spinal nerves

A

• Dermatomes

33
Q

• Loss of sensation of a particular ____ (or skin region) indicates damage to the corresponding spinal nerves

A

dermatome

34
Q
  • The peripheral distribution of spinal nerves discussed so far apply mainly to the THORACIC nerves
  • This distribution is different in nerves that control the skeletal muscles of the neck and upper/lower limbs (cervical, lumbar, and sacral nerves)
  • Distribution of Cervical, sacral, and Lumbar spinal nerves
  • The ventral rami of these regions form a complex interwoven network of nerve fibers called a Nerve Plexus
A

Spinal Nerves and Plexuses

35
Q
  • The intermixing or blending of fibers of ventral rami of one spinal nerve with adjacent spinal nerves
  • Ultimately give rise to specific nerves that control skeletal muscles of the neck and limbs
A

• Nerve Plexuses

36
Q
  • Includes ventral rami of spinal nerves C1–C5
  • Innervates neck, thoracic cavity, diaphragmatic muscles
  • Major nerve (but not the only)
  • Phrenic nerve (controls diaphragm)
A

• The Cervical Plexus

37
Q
  • Includes ventral rami of spinal nerves C5–T1

* Innervates pectoral muscles and upper limbs

A

• The Brachial Plexus

38
Q
  • Includes ventral rami of spinal nerves T12–L4

* Innervate pelvic area and lower limbs)

A

• The Lumbar Plexus

39
Q
  • Includes ventral rami of spinal nerves L4–S4
  • Innervate lower limbs and feet
  • Major nerves
  • Sciatic nerve and some of its branches
  • Fibular nerve
  • Tibial nerve
A

• The Sacral Plexus

40
Q
  • About 10 million

* Deliver information to CNS

A

• Sensory neurons

41
Q
  • About 1/2 million

* Deliver commands to peripheral effectors

A

• Motor neurons

42
Q
  • Only in CNS
  • About 20 billion
  • Interpret, plan, and coordinate incoming and outgoing signals
A

• Interneurons

43
Q

• Functional groups of interconnected neurons (interneurons)
• Can involve neurons in one or several brain or spinal cord regions
• Pattern of organization of neuronal pools =
» NEURAL CIRCUIT

A

• Interneurons are organized into Neuronal Pools

44
Q

• An axon of one neuron has several collaterals that communicate with several neurons

A

• Divergence

45
Q

• A neuron receives communication from many neurons

A

• Convergence

46
Q
  • Moves information in single line or a stepwise fashion

* Neurons or pools work sequentially

A

• Serial processing

47
Q

• Moves same information along several paths simultaneously

A

• Parallel processing

48
Q
  • Positive feedback mechanism whereby axons go back to the source of the impulse to further stimulate neurons
  • Functions (keeps going) until inhibited
A

• Reverberation

49
Q

• The various interconnections that occur among neurons and between neuronal pools produce

A

simple AND complex reflexes

50
Q
  • Rapid, automatic responses to specific stimuli
  • Coordinated in the spinal cord
  • One neural reflex produces one motor response that typically does not vary
  • Basic building blocks of neural function
A

Neural Reflexes

51
Q
  • The wiring of a single reflex
  • Beginning at receptor
  • Ending at peripheral effector
  • Generally opposes original stimulus (negative feedback)
A

• Reflex arc

52
Q
  • Step 1: Arrival of stimulus, activation of receptor
  • Physical or chemical changes
  • Step 2: Activation of sensory neuron
  • Graded depolarization (graded, not action, potential)
  • Step 3: Information processing in the CNS
  • Triggered by neurotransmitters
  • Step 4: Activation of motor neuron
  • Action potential
  • Step 5: Response of peripheral effector
  • Triggered by neurotransmitters
A

Five Steps in Neural Reflexes

53
Q
  • Sensory receptor
  • Afferent neuron
  • Integration center
  • Efferent neuron
  • Effector organ
A

Summary of the Neural Pathway for a Reflex

Consists of Five Components

54
Q

• Reflex arc: 1) muscle spindle → 2) Afferent neurons

→ 3) Spinal cord → 4) Efferent neurons → 5) Quadriceps muscle

A

• Knee jerk reflex

55
Q

• Reflex arc: 1) Photoreceptors → 2) Afferent neurons

→ 3) Midbrain nuclei → 4) Efferent neurons → 5) Pupils

A

• Pupillary reflex

56
Q
  • Integration occurs in the spinal cord

* Example: muscle spindle stretch reflex (knee-jerk reflex)

A

• Spinal (by site of information processing)

57
Q
  • Integration occurs in the brain

* Example: pupillary reflex (pupil constricts in response to light)

A

• Cranial (by site of information processing)

58
Q
  • basic neural reflexes formed before birth
  • Inborn reflexes that all neurologically normal people are born with
  • Example: pupillary reflex (pupil constricts in response to light)
A

• Innate reflexes (by early development)

59
Q
  • learned motor patterns
  • Reflexes that develop as a result of experience – these differ according to each person’s life experiences
  • Example: salivation of Pavlov’s dog
A

• Acquired reflexes(by early development) :

60
Q
  • Involve signals sent to skeletal muscles via somatic neurons
  • Example: muscle spindle stretch reflex (knee-jerk reflex)
A

• Somatic (skeletal) (by motor response)

61
Q
  • Involve signals sent to smooth muscle, cardiac muscle, and glands via autonomic neurons
  • Example: baroreceptor reflex to control blood pressure
A

• Automatic (Visceral) (by motor response)

62
Q

• Reflexes which involve a neural pathway consisting of only two neurons and one synapse
• Example:
– muscle spindle stretch reflex (knee-jerk reflex)
– Postural reflex

A

• Monosynaptic (by complexity of neural circuit)

63
Q

• Reflexes which involve more than two neurons and multiple synapses (and more complex)
• Examples are most other reflexes
– Tendon reflex
– Withdrawal reflex

A

• Polysynaptic (by complexity of neural circuit)

BIO 181-171 (12 decks)

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