Bio Lecture 9

Question 1

_______– all neurons have the ability to respond to environmental changes

Answer 1

Excitability

Question 2

________– Neurons produce traveling electrical signals that quickly reach other cells at distant locations

Answer 2

Conductivity

Question 3

________– when the electrical signal reaches the end of a nerve fiber, the neuron usually secretes a chemical called a neurotransmitter that stimulates the next cell

Answer 3

Secretion

Question 4

__________ neurons – neurons specialized to detect stimuli such as light, temperature, or pressure and to transmit information about them towards the CNS

Answer 4

Sensory (afferent)

Question 5

________ (association neurons) – neurons located entirely within the brain or spinal cord

Answer 5

Interneurons

Question 6

These neurons carry out the integrative function of the nervous system – they process, store and retrieve information, and “make decisions” about how the body responds to stimuli

_________

Answer 6

Interneurons

Question 7

________ (efferent) neurons – neurons that send signals to muscle or gland cells, sending signals away from the central nervous system

Answer 7

Motor

Question 8

_____ (cell body) – control center of the neuron

Has a nucleus and cytoplasm containing organelles like other cells

Answer 8

Soma

Question 9

________- processes of a neuron that receives information from other cells or from environmental stimuli

It conducts signals toward the soma

________ are usually shorter, more branched, and more numerous than the axon

Answer 9

Dendrites

Question 10

_____ – process of a neuron that conducts action potentials away from the soma

Each neuron has only one ____

Answer 10

Axon

Question 11

The _____ end of an axon usually has termina arborization

Terminal arborization is an extensive complex of fine branches

Answer 11

distal

Question 12

Each branch ends in a _______ _____ (terminal button)

Swollen tip of the distal end of an axon; the site of synaptic vesicles and neurotransmitter release

Answer 12

synaptic knob

Question 13

_______ neurons – Have one axon and two or more dendrites

This type is common in the brain and spinal cord

Answer 13

Multipolar

Question 14

______ neurons – have one axon and one dendrite

Includes olfactory cells and sensory cells of the inner ear

Answer 14

Bipolar

Question 15

______ neurons – have only one process leading away from the soma

Also called pseudounipolar neurons

Includes neurons that carry signals to the spinal cord

Answer 15

Unipolar

Question 16

_______ neurons – have multiple dendrites but no axon

This type is found in the brain and retina

Answer 16

Anaxonic

Question 17

__________ – Forms a myelin sheath around nerve fibers in the central nervous system

Answer 17

Oligodendrocytes

Question 18

_________ – form the blood-brain barrier that controls which substances are able to get from the bloodstream into the brain tissue

Answer 18

Astrocytes

Question 19

________ Cells – produce cerebrospinal fluid and help to circulate cerebrospinal fluid

Answer 19

Ependymal

Question 20

_______– develop from white blood cells and phagocytize dead nervous tissue, microorganisms, and other foreign matter

Answer 20

Microglia

Question 21

________ Cells – envelop peripheral nervous system fibers with myelin and assist in the regeneration of damaged fibers

Answer 21

Schwann

Question 22

Insulating layer around a nerve fiber

Formed by oligodendrocytes in the CNS and Schwann cells in the PNS

_________

Answer 22

Myelin

Question 23

Axons are covered in segments

Gaps between segments are called nodes of Ranvier

Myelin-covered areas between nodes of Ranvier are called internodes

Answer 23

Axons are covered in segments

Gaps between segments are called nodes of Ranvier

Myelin-covered areas between nodes of Ranvier are called internodes

Question 24

In an unmyelinated nerve fiber, the signal spreads by diffusion of sodium and potassium ions through the plasma membrane at every point along the fiber

The ion movement creates a sudden voltage change called an action potential at each point

Answer 24

Each action potential triggers another one just ahead of it

The nerve signal consists of a wave of action potentials traveling down the axon

This signal travels at about .5 to 2 m/sec

Question 25

In a myelinated nerve fiber, the ion movements through the membrane occur only at the ____ __ _______ (gaps between segments of myelin)

Answer 25

nodes of Ranvier

Question 26

In the _______ (myelin covered portions), signals travel by a much faster process of ion diffusion along the length of the nerve fiber immediately under the plasma membrane the signal can travel as fast as 120 m/sec

Answer 26

internodes

Question 27

________– the meetings between neurons and any other cells

Answer 27

Synapses

Question 28

________ _______ – junctions in which the presynaptic neuron releases a neurotransmitter to stimulate the postsynaptic cell

Answer 28

Chemical synapses

Question 29

At a chemical synapse, a terminal branch of a presynaptic fiber ends in a swelling called the synaptic knob

Answer 29

Between the synaptic knob and the next cell there is a 20-40 nm gap called the synaptic cleft A nerve signal arrives at the end of the presynaptic neuron and triggers the release of neurotransmitters that either excite or inhibit the postsynaptic cell

Question 30

______ ________ – junctions in which adjacent cells are joined by gap junctions Ions diffuse directly from one cell to the next for quick transmission

Answer 30

Electrical synapses

Question 31

________– the spinal cord contains fibers that conduct information up and down the body It enables sensory information to reach the brain It enables motor commands to reach the receptors Input received at one level of the spinal cord can affect output at another level

Answer 31

Conduction

Question 32

_________– the simple repetitive muscle contractions that put one foot in front of another are controlled by central pattern generators in the spinal cord The spinal cord does not control the speed or direction of locomotion (those are under control of the motor neurons in the brain)

Answer 32

Locomotion

Question 33

________– the spinal cord is responsible for involuntary stereotyped responses to stimuli

Answer 33

Reflexes

Question 34

31 pairs of spinal nerves over five regions 8 Cervical (C1-C8) 12 Thoracic (T1-T12) 5 Lumbar (L1-L5) 5 Sacral (S1-S5) 1 Coccygeal

Answer 34

31 pairs of spinal nerves over five regions 8 Cervical (C1-C8) 12 Thoracic (T1-T12) 5 Lumbar (L1-L5) 5 Sacral (S1-S5) 1 Coccygeal

Question 35

The diameter of the spinal cord is relatively constant except for the cervical enlargement and lumbar enlargement

Answer 35

The diameter of the spinal cord is relatively constant except for the cervical enlargement and lumbar enlargement

Question 36

________ ___________ Location in which the cord tapers to a point below the lumbar enlargement

Answer 36

Conus medullaris

Question 37

______ _______ Bundle of nerves resembling a horse’s tail that innervates the pelvic organs and lower limbs

Answer 37

Cauda equina

Question 38

___ _______ – outermost meninx that forms a dural sheath around the spinal cord

Answer 38

Dura mater

Question 39

______ space is found between the sheath and the vertebral bone * It is a space filled with blood vessels, loose connective tissue, and adipose tissue * It is a site where anesthetics are sometime introduced to block pain signals

Answer 39

Epidural

Question 40

______- middle meninx that adheres to the inside of the dura mater composed of a loose mesh of collagenous and elastic fibers

Answer 40

Arachnoid

Question 41

___________ space is the gap between the arachnoid and the pia mater Filled with cerebrospinal fluid

Answer 41

Subarachnoid

Question 42

________ _______ is a (subarachnoid) space occupied by the cauda equina below the medullary cone

Answer 42

Lumbar cistern

Question 43

___ ______ – innermost layer of the meninges that closely follows the contours of the spinal cord

Answer 43

Pia mater

Question 44

____ matter – has a dull color because it contains very little myelin Contains the somas, dendrites, and proximal parts of the axons of neurons

Answer 44

Gray

Question 45

______ matter – has a pearly white color because it contain myelin Composed of axons that carry signals from one part of the CNS to another

Answer 45

White

Question 46

Spinal Tracts: (2)

Answer 46

Ascending tracts Descending tracts

Question 47

_____– cordlike organ composed of axons bound together by connective tissue

Answer 47

Nerve

Question 48

_____ nerve – consists of both sensory and motor fibers and transmits signals in two directions (but any one fiber transmits in only one direction)

Answer 48

Mixed

Question 49

______ nerve – consists of sensory axons, including those of the olfactory and optic nerves

Answer 49

Sensory

Question 50

_____ nerve – consists of motor fibers only Many motor nerves are actually mixed nerves because they also carry sensory signals from muscles back to the CNS

Answer 50

motor

Question 51

_______– a cluster of cell bodies outside the CNS (resembling a knot).

Answer 51

Ganglion

Question 52

Proximal Branches (2)

Answer 52

Dorsal root- afferent signals Ventral root- efferent signals

Question 53

_____ _____ – innervates the muscles and joints in that region to the spine and the skin of the back

Answer 53

Dorsal ramus

Question 54

______ ____ – innervates the ventral and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs In the thoracic region, it forms the intercostals nerve

Answer 54

Ventral ramus

Question 55

Except in the thoracic region, the ventral rami form web-like nerve plexuses which carry signals from bones, joints, muscles, and the skin

Answer 55

Except in the thoracic region, the ventral rami form web-like nerve plexuses which carry signals from bones, joints, muscles, and the skin

Question 56

o ______ Plexus (C1-C5) – Great Auricular nerve (sensory nerve of skin of and around the ear) Transverse Cervical nerve (sensory nerve of skin of ventral and lateral neck) Ansa Cervicalis (motor nerve of omohyoid, sternohyoid, and sternothyroid) Phrenic nerve (motor nerve of the diaphragm)

Answer 56

Cervical

Question 57

_______ Plexus (C5-T1) Axillary nerve Radial nerve Musculocutaneous nerve Median nerve Ulnar nerve

Answer 57

Brachial

Question 58

________ Plexus (L1-L4) Ilioinguinal nerve Lateral femoral cutaneous nerve Femoral nerve Obturator nerve

Answer 58

Lumbar

Question 59

______Plexus (L4-S4) Superior gluteal nerve Inferior gluteal nerve Sciatic nerve Tibial nerve Common fibular (peroneal) nerve

Answer 59

Sacral

Question 60

Each spinal nerve receives sensory input from a specific area of skin called a dermatome

Answer 60

Dermatomes overlap at their edges by as much as 50%, so severing one sensory nerve root does not entirely deaden sensation from a dermatome

Question 61

Reflexes Require stimulation – they are responses to sensory input They are quick – they involve few if any interneurons and minimal synaptic delay Involuntary – they occur without intent, often without our awareness, and they are difficult to suppress Stereotyped – they occur in essentially the same way every time, in a predictable manner

Answer 61

Reflexes Require stimulation – they are responses to sensory input They are quick – they involve few if any interneurons and minimal synaptic delay Involuntary – they occur without intent, often without our awareness, and they are difficult to suppress Stereotyped – they occur in essentially the same way every time, in a predictable manner

Question 62

_______ reflexes use simple neural pathways called reflex arcs that send signals from the sensory nerve ending to the spinal cord or brainstem and back to a skeletal muscle

Answer 62

Somatic

Question 63

_______ reflex arc – simplest type of reflex arc, consisting only of a sensory neuron and a motor neuron (with just one synapse between neurons)

Answer 63

Monosynaptic

Question 64

________reflex arc – reflex arc containing one or more association neurons

Answer 64

Polysynaptic

Question 65

_________ reflex – CNS input and output are on the same side of the body

Answer 65

Ipsilateral

Question 66

________ reflex – sensory input enters the spinal cord on one side of the body and the motor output leaves from the opposite side

Answer 66

Contralateral

Question 67

__________reflex – Sensory signal enters the spinal cord at one level, and the motor output leaves the cord from a higher or lower level.

Answer 67

Intersegmental