Chapters 10-12 Study Guide Flashcards
1
Q
What are the four general functions of the nervous system?
A
-Detect changes (sensory)
-Make decisions (integrative)
-Stimulate muscles and glands to respond (motor response)
-Maintain homeostasis
2
Q
Describe the sensory division?
A
Utilizes sensory receptors to receive information and the relays that information to the CNS
3
Q
Describe the motor division?
A
It is comprised of the somatic and the autonomic divisions. It puts decisions into action by carrying impulses to effectors (muscles/glands)
4
Q
What are the names of the cell body of a neuron?
A
-Cell body
-Soma
-Perikaryon
5
Q
What are the 9 structures of a neuron?
A
-Cell body
-Dendrites
-Axon hillock
-Axon
-Synaptic knob
-Schwann cell
-Myelin
-Myelin sheath
-Node of Ranvier
6
Q
What are the five roles of neuroglia?
A
-Provide structural support
-Guide embryonic neurons into position
-Produce growth factors to nourish neurons
-Assists in the formation of synapses
-Clears excess ions and neurotransmitters
7
Q
What are the four neuroglia of the CNS?
A
-Astrocytes
-Oligodendrocytes
-Microglia
-Ependyma
8
Q
What are the two neuroglia of the PNS?
A
-Schwann cells
-Satellite cells
9
Q
What are the five functions of astrocytes?
A
-Connects neurons to blood vessels
-Exchange nutrients and growth factors
-Form scar tissue
-Regulate ion concentration
-Part of BBB
10
Q
What are the two functions of oligodendrocytes?
A
-Myelinate CNS axons
-Provide structural support
11
Q
Describe microglia?
A
-Phagocytic cell
-Provide structural support
12
Q
Describe ependyma?
A
-Line central canal of the spinal cord
-Line ventricles of the brain
-Regulates composition of cerebrospinal fluid (CSF)
-Made of ciliated cuboidal/columnar cells
13
Q
What is the function of schwann cells?
A
Produce the myelin sheath found on some peripheral axons which speeds up nerve impulse transmission
14
Q
What is the function of satellite cells?
A
Support clusters of neuron cells bodies (ganglia)
15
Q
Describe sensory neurons?
A
Afferent neurons that carry impulses to the CNS. (unipolar but some are bipolar)
16
Q
How are neurons classified?
A
By the number of extensions radiating from their cell body
17
Q
What are the different classifications of neurons by type?
A
-Multipolar
-Bipolar
-Unipolar
18
Q
Describe multipolar neurons?
A
-99% of neurons
-Many processes
-Most neurons of the CNS
19
Q
Describe bipolar neurons?
A
-Two process
-associated with special senses (eyes, ears, nose)
20
Q
Describe unipolar neurons?
A
-One process
-Cell bodies are in ganglia
-Sensory
21
Q
What are the three classes of neurons by function?
A
-Sensory
-Interneurons
-Motor neurons
22
Q
Describe sensory neurons?
A
-Afferent neurons
-Carry impulses to CNS
-Some are bipolar
23
Q
Describe interneurons?
A
-Links neurons together
-multipolar
-located within the CNS
24
Q
Describe motor neurons?
A
-Efferent
-Multipolar
-Carry impulses away from the CNS
-Deliver signals to effectors
25
How do neurons respond to stimuli?
-Neurons are excitable cells
-They detect stimuli and respond by changing their resting potential
-The common response is the opening of a gated ion channel
-The causes the resting potential to become less negative (depolarization)
-If depolarization reaches -55mV then the threshold potential has been reached and an action potential results
26
What are the five phases of neurons responding to stimuli?
-Resting potential
-Depolarization
-Repolarization
-Hyperpolarization
-Resting potential reestablished
27
Describe membrane potential and distribution of ions?
The resting membrane potential is the potential difference in charge across the axon membrane which is the -70mV being on the inside which means the membrane is polarized. The inside contains K+ (potassium) while the outside contains Na+ (Sodium) and Cl- (chlorine)
28
What are the eight steps that lead to an impulse conduction or the generation of an action potential?
1. Nerve cell membrane maintains resting potential by diffusion of Na+ and K+ down their concentration gradients as the cell pumps them up the gradeints
2. Neurons receive stimulation, causing local potentials, which may sum to reach a threshold
3. Sodium channels in the trigger zone of the axon open
4. Sodium ions diffuse inward, depolarizing the membrane
5. Potassium channels in the membrane open
6. Potassium ions diffuse outward, repolarizing the membrane
7. The resulting action potential causes an electric current that stimulates adjacent portions of the membrane
8. Action potentials occur sequentially along the length of the axon
29
What does all-or-none response mean?
If an axon responds at all, it responds completely with an action potential
30
All impulses carried on an axon are the ____ ____?
Same strength
31
Stimulus of greater intensity produces ____ ___ of action potentials, not stronger impulses?
Higher frequency
32
Threshold potential?
Level of potential at which an action potential is triggered in a neuron or muscle fiber.
33
Saltatory conduction?
Impulse conduction along a myelinated axon that seems to jump from one node to the next
34
How does conduction in myelinated and unmyelinated neurons vary?
Myelin helps increase the conduction velocity of a nerve impulse and uses saltatory conduction
35
Depolarization?
The membrane of a neuron becoming less negative (more positive) than the resting potential
36
Repolarization?
The process of a membrane becoming polarized once again
37
What are the two refractory periods?
Absolute refractory period and relative refractory period
38
Absolute refractory period?
Time when threshold stimulus cannot generate another action potential due to voltage-gated Na+ channels being unresponsive
39
Relative refractory period?
The time when only high-intensity stimulus can generate another action potential. This is when repolarisation is not complete and the membrane is still re-establishing resting potential
40
Neurotransmitter?
A chemical that an axon secretes into a synapse that stimulates or inhibits an effort (muscle or gland) or other neuron
41
Excitatory neurotransmitter?
A neurotransmitter that increases postsynaptic membrane permeability to sodium ions which bring the postsynaptic membrane closer to threshold
42
Inhibitory neurotransmitter?
A neurotransmitter that makes an impulse less likely to occur
43
Synapse?
A site at which a neuron transmits a nerve impulse to another neuron
44
Synaptic potential?
A change in the membrane potential of the postsynaptic cell
45
What is convergence?
Two or more presynaptic neurons forming synapses with the same postsynaptic neuron
46
What is divergence?
A single neuron having synapses with two or more post synaptic cells
47
Describe the structure of the spinal cord longitudinally?
The spinal cord is a slender column of nervous tissue that runs continuously with the brainstem.
-Begins at the foramen magnum
-Has a cervical enlargement
-Extends down through the vertebral canal and has 31 segments each of which branches into a pair of spinal nerves
-Has a lumbar enlargement
-Conus medullaris: terminates at L1 & L2 vertebrae
-Cauda equina: horse's tail
-Filum terminale
48
Describe the structure of the spinal cord from a cross-sectional view?
Composed of gray and white matter and divided which looks like a butterfly in the center.
Center
-Anterior median fissure
-Central canal
-Gray commissure
-Posterior median sulcus
Gray (butterfly)
-Anterior horn
-Lateral horn
-Posterior horn
White (outside)
-Anterior funiculus
-Lateral funiculus
-Posterior funiculus
Surronding structures
-Ventral root
-Dorsal root
-Dorsal root ganglion
49
Functions of the spinal cord?
-Pathway for impulses to and from the brain
-Center for spinal reflexes
50
What is a refelx?
An automatic, subconscious response to stimuli within or outside the body
51
What is a reflex arc?
A neural pathway that consists of a sensory receptor + 2 or more neurons + an effector
52
What is a simple reflex arc?
Sensory and motor neuron
53
What is the most common type of reflex arc composed of?
Sensory neuron, interneuron, and motor neuron
54
Describe the knee-jerk reflex?
A monosynaptic (stretch) reflex consists of only one synapse and two neurons (sensory + motor)
55
Describe a withdrawal reflex?
Occurs when you touch or step on something painful. It helps prevent tissue damage by removing the limb from the source of the injury. It is a polysynaptic pathway (sensory neuron + [synapse] + interneuron + [sysnpase] + motor neuron)
56
What is reciprocal innervation?
-Flexors contract
-Extensors are inhibited
57
Describe reflex behavior or a reflex?
Reflexes are automatic responses to stimuli inside or outside the body. They help maintain homeostasis by controlling many involuntary processes such as heart rate, breathing rate, blood pressure, and digestion. They consist of monosynaptic reflexes, withdrawal reflexes, and crossed-extensor reflexes
58
What is a crossed extensor reflex?
This occurs when flexors on the affected side contract and extensors on the contralateral side also contact to stabilize the body during the withdrawal reflex. It helps shift weight to ensure one does not fall during a withdrawal reflex
59
What are the parts of a reflex arc?
-Receptor (sensitive to change)
-Sensory neuron (conducts impulse to CNS)
-Interneuron (processing center/conducts impulse)
-Motor neuron (conducts impulse from CNS to effector)
-Effector (muscle or gland which responds to stimulation)
60
Describe ascending tracts?
Conduct sensory impulses to the brain.
-Fasciculus gracilis
-Fasciculus cuneatus
-Spinothalamic tracts (lateral and anterior)
-Spinocerebellar tracts (posterior and anterior)
61
Describe descending tracts?
Conduct motor impulses from the brain to motor neurons reaching muscels or glands.
-Corticospinal tracts (lateral and anterio)
-Reticulospinal tracts (lateral and medial)
-Rubrospinal tracts
62
Describe the PNS?
Composed of cranial and spinal nerves
PNS
/\
Sensory Motor
/\
Somatic Autonomic
Somatic: Cranial and spinal nerves that connect CNS to skin and skeletal muscle for voluntary action
Autonomic: Cranial and spinal nerves that connect CNS to viscera for involuntary action
63
Describe the structure of peripheral nerves?
-Epineurium
-Nerve
-Perineurium
-Fascicle
-Endoneurium
-Neuron with motor ending and sensory receptor
64
What are the general features of cranial nerves?
-12 pairs
-Attached to the brainstem except for the 1st and 2nd pairs
65
What are the twelve cranial nerves and their type?
I-Olfactory-Sensory
II-Optic-Sensory
III-Oculomotor-Motor
IV-Trochlear-Motor
V-Trigeminal-Both
VI-Abducens-Motor
VII-Facial-Both
VIII-Vestibulocochlear-Sensory
IX-Glossopharyngeal-Both
X-Vagus-Both
XI-Accessory-Motor
XII-Hypoglossal-Motor
66
Describe spinal nerves?
All 31 pairs are mixed nerves except the first pair.
-8 cervical
-12 thoracic
-5 lumbar
-5 sacral
-1 coccygeal
Each spinal nerve splits into a dorsal/posterior/sensory root (has dorsal root ganglion) and a ventral/anterior/motor root(cell bodies in the spinal cord)
Spinal nerves= ventral + dorsal (the union)
67
What is the cauda equina?
Formed from descending roots of lumbar, sacral, and coccygeal nerves
68
What is the cauda equina?
Formed from descending roots of lumbar, sacral, and coccygeal nerves
69
Describe cranial nerve I?
Olfactory nerve (I):
-sensory nerve only
-associated with sense of smell
-bipolar neurons; pass through cribriform plate of ethmoid bone, and enter olfactory bulbs
70
Describe cranial nerve II?
Optic nerve (II):
-sensory nerve only
-associated with sense of vision
-neuron cell bodies form ganglion layers of retina, and pass through optic foramina of the orbits
71
Describe cranial nerve III?
Oculomotor nerve (III):
-primarily motor nerve
-motor impulses to several voluntary muscles that raise eyelids, move the eyes
-motor impulses to involuntary muscles that focus lens, adjust light entering eye (part of autonomic nervous system)
-small sensory component (proprioceptive fibers)
72
Describe cranial nerve IV?
Trochlear nerve (IV):
-smallest pair of cranial nerves
-primarily motor nerve
-motor impulses to one pair of muscles that move the eyes
-small sensory component (proprioceptive fibers)
73
Describe cranial nerve V?
Trigeminal nerve (V):
-mixed nerve
-largest pair of cranial nerves
-3 large sensory branches:
Ophthalmic division: Sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
Maxillary division: Sensory from upper teeth, upper gum, upper lip, palate, and skin of face
Mandibular division: Sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip
Motor to muscles of mastication
74
Describe cranial nerve VI?
Abducens nerve (VI):
-primarily motor nerve
-motor impulses to one pair of muscles that move the eyes
-some sensory (proprioceptive fibers)
75
Describe cranial nerve VII?
Facial nerve (VII):
-mixed nerve
-sensory from taste receptors Motor to muscles of facial expression, tear glands, and salivary glands
76
Describe cranial nerve VIII?
Vestibulocochlear nerve (VIII):
-acoustic or auditory nerve
-sensory nerve only
2 branches:
Vestibular branch:
Sensory from equilibrium receptors of ear.
Cochlear branch:
Sensory from hearing receptors.
77
Describe cranial nerve IX?
Glossopharyngeal nerve (IX):
-mixed nerve
-sensory from pharynx, tonsils, part of tongue (the region posterior to the nasal cavity, the oral cavity and the larynx)
-motor to salivary glands and muscles of pharynx (for swallowing)
78
Describe cranial nerve X?
Vagus nerve (X):
-mixed nerve
-somatic motor to muscles of speech and swallowing
-autonomic motor to heart, other viscera of thorax and abdomen
-sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
79
Describe cranial nerve XI?
Accessory nerve (XI):
-primarily motor nerve
-formerly called “Spinal Accessory”
contain cranial and spinal branches:
cranial branch:
-Join Vagus N.; motor to muscles of soft palate, pharynx and larynx.
spinal branch:
-Motor to muscles of neck and back.
-Small sensory component (proprioceptive fibers).
80
Describe cranial nerve XII?
Hypoglossal nerve (XII):
-primarily motor
-motor to muscles of the tongue for speaking, chewing, swallowing
-small sensory component (proprioceptive fibers)
81
Describe plexuses?
A complex network formed by ventral rami of spinal nerves. Plexus comes from the greek word for "braided."
82
What plexes does each segment of the spinal cord divide into?
-C1-C4 cervical plexus
-C5-T1 brachial plexus
-T2-T12 become intercostal nerves
-L1-S4 lumbosacral plexus
83
Describe the brachial plexus?
Between C5-T1 and lies deep in the shoulder. Has five branches
-Musculocutaneous nerves (muscles of anterior arms and skin of forearms)
-Ulnar and median nerves (Muscles of forearms and hand; skin of hands)
-Radial nerve (Posterior muscles of arms and skin of forearms and hands)
-Axillary nerve (muscle and skin of anterior and lateral and posterior arms)
84
Describe the lumbosacral plexus?
Formed from L1-S4 and extends from the lumbar region into the pelvic cavity. Has three divisions.
-Obturator nerves (supplies motor impulse to adductors of the thigh)
-Femoral nerve (Supplies motor impulse to muscles of anterior thigh and sensory impulses from skin and legs)
-Sciatic nerve (supplies muscle and skin of thighs, legs, and feet; largest and longest nerve in the body)
85
Describe the ANS?
Branch of the PNS which is involuntarily controlled.
-Controls visceral activities
-Regulates smooth and cardiac muscles; and glands
-Helps maintain homeostasis
-Helps the body respond to stress
-Prepares the body for intense physical activity
Can be divided into the sympathetic and parasympathetic divisions
Unlike the somatic pathways, the ANS uses four neurons in its reflex arc
86
What are the four neurons in the reflex arc of the ANS?
-Sensory neuron
-Interneuron
-Preganglioinic neuron
-Postganglionic neuron
87
What are the two types of ANS neurotransmitters?
Acetylcholine and norepinephrine
88
What are the four types of ANS neurotransmitter receptors?
Cholinergic receptors (bind to acetylcholine)
-Muscarinic receptors: excitatory and slow
-Nicotinic receptors: excitatory and rapid
Adrenergic receptors (bind to epinephrine and norepinephrine)
-Alpha receptors
-Beta receptors
89
What are five different categories of neurotransmitters in the ANS?
-Acetylcholine (controls muscle action)
-Norepinephrine (sense of well-being increases HR and BP)
-Epinephrine (adrenaline)
-Dopamine (sense of well-being)
-Serotonin (Inhibitory leads to sleepiness)
90
What are the five different types of receptors?
-Chemoreceptors
-Nociceptors
-Thermoreceptors
-Mechanoreceptors
-Photoreceptors
91
Describe cholinergic receptors?
Cholinergic receptors bind to acetylcholine and have two types:
-Muscarinic receptors; excitatory, slow
-Nicotinic receptors; excitatory, rapid
92
Describe adrenergic receptors?
Bind to epinephrine and norepinephrine and have two types:
-Alpha receptors
-Beta receptors
93
Describe a preganglionic neuron?
-Neuron cell bodies are in the CNS
94
Describe a postganglionic neuron?
Neuron cell bodies are in the ganglia; extend to the visceral effector
95
Describe the sympathetic division?
-AKA thoracolumbar division (T1-L2)
-Have sympathetic trunks
96
Describe preganglionic neurons in the sympathetic division?
-synapse with a postganglionic neuron in a paravertebral ganglion
-continue through a paravertebral ganglion, and synapse at another sympathetic ganglion
-pass through to collateral ganglia to synapse there
97
Describe postganglionic fibers in the sympathetic division?
-extend from sympathetic ganglia to visceral effector organs
-postganglionic fibers that originate at paravertebral ganglia usually pass through gray rami & return to a spinal nerve before proceeding to an effector
-EXCEPTION: preganglionic fibers pass through sympathetic ganglia & extend to adrenal medulla; these terminate on hormone-secreting cells that release epinephrine & norepinephrine (ie., adrenaline)
98
The function of sympathetic division?
-fight or flight response
-speeds body up
-most active under energy-requiring, stressful situations
99
The function of the parasympathetic division?
-resting & digesting
-slows body down
-most active under resting, non-stressful conditions
100
Describe the parasympathetic division?
-AKA the craniosacral division (brainstem and S2-S4
-Preganglionic fibers extend out on cranial or sacral nerves to terminal ganglia the short postganglionic fibers continue to specific muscles or glands
101
The autonomic division is controlled mostly by the ____ via ____ processes?
Hypothalamus via involunatary
102
____ ____ regulates cardiac, vasomotor, and respiratory activities?
Medulla oblangata
103
Sensation?
An awareness that impulses associated with a sensory event have reached the brain
104
Perception?
Mental interpretation of sensory stimulation
105
Projection?
The process by which the cerebral cortex interprets the sensation as being derived from certain receptors (allows the person to pinpoint the region being stimulated)
106
Sensory adaptation?
Represents the ability to ignore unimportant or continuous stimuli
-Peripheral adaptation: receptor level
-Central adaptation: pathways leading to the cerebral cortex
107
Pressure sensing?
-Detected by lamellated/pacinian corpuscles which are common in deep subcutaneous tissues, tendons, and ligaments
-Heavy pressure and vibrations
108
Touch sensing?
-Detected by tactile/meissner's corpuscles which are abundant in hairless portion of the skin and lips
-Fine touch and texture
109
Describe temperature senses?
Thermoreceptors exist as free nerve ending in the skin and have three levels
-Warm receptors 25C-45C (77F-113F)
-Cold receptors 10C-20C (50F-68F)
-Nociceptors/pain receptors <10C (55F) freezing sensation...45C (113F)< burning sensation
110
Describe pain receptors?
-AKA nocireceptors
-Widely distributed (lacking in nervous tissue of brain)
-Stimulated by tissue damage, chemical, mechanical forces or temperature extremes
-Minimally adaptive
-Pain receptors produce sensations in the viscera
111
Naturally produced pain-inhibiting substances?
-Enkephalins
-Serotonin
-Endorphins
112
Exteroceptive senses?
-Body surfaces
-Touch, pressure, temperature, and pain
113
Interoceptive senses?
-AKA visceroceptive senses
-Associated with viscera
-ef., blood pressure stretching vessels
114
Proprioceptive senses?
-Associated with changes in muscles, tendons, and joints
115
Referred pain?
-Pain that feels as if it is originating from a part other than the site being stimulated
-The result of a visceral organ and skin area synapsing with the CNS neuron
116
Describe the two types of pain pathways?
Fast pain/A-delta fibers
-Myelinated
-Conduct impulses rapidly (up to 30m/s)
-Sharp/acute pain in a localized area
-Stops when stimulus ceases
Slow pain/C fibers
-Unmyelinated
-Conduct impulses slowly (up to 2m/s)
-Dull, aching, chronic pain
-difficult to localize
-Continues after stimulation stops
117
How is pain naturally regulated?
1. Thalamus (begins sensation of pain)
2. Cerebral cortex (judges intensity, locates sources, produces emotional and motor response)
3. Brainstem: gray matter (Regulates flom of impulses from the spinal cord)
Inhibitory substances are secreted such as:
-Enkephalins
-Serotonin
-Endorphins
118
Describe muscle spindles?
-Mechanoreceptors that sense changes in muscle length
-Stretch receptors in skeletal muscles
-Initiate stretch reflexes to cause muscle contraction
119
Describe the golgi tendon organ?
-Stretch receptors in tendons
-Stimulate reflexes that oppose stretch reflexes
-Help maintain posture; prevent tearing away of muscles from the insertion
120
Describe visceral senses?
-The receptors of internal organs
-eg., lamellated corpuscles and free nerve endings
-Conveys information such as sense of fullness, discomfort of intestinal gas, pain that signals a heart attack
121
What are the five special senses?
-Smell
-Taste
-Hearing
-Equalibrium
-Sight
122
Describe olfactory receptors?
-Olfactory receptors are a type of chemoreceptor
-They respond to chemicals dissolved in fluids
-Sense of smell provides 75-80% of taste
123
Describe the pathway of olfactory receptors?
-Olfactory nerves
-Olfactory bulbs
-Olfactory tracts
-Brain
124
Describe olfactory stimulation?
Each olfactory receptor cell contains 1 0f 400 membrane proteins that bind to several odorants. The interprets these olfactory codes for the smell. Olfactory receptors undergo adaptation rapidly (50% after 1 minute) and are easily damaged.
125
What is gustation?
The sense of taste
126
Describe taste receptors?
-Taste buds are the organs of taste and are located on the papillae of the tongue, roof of the mouth, linings of cheeks, and walls of the pharynx
-10,000 taste buds each with 50-150 taste cells
-Taste cells are modified epithelial cells that function as receptors that feature taste hairs, a type of microvilli that protrude from taste cells through pores of taste buds
-Taste receptors are a type of chemoreceptors which are replaced every three days
127
What are the five taste sensation?
-Sweet (stimulated by carbohydrates)
-Sour (stimulated by acids)
-Salty (ionized inorganic salts)
-Bitter (organic compounds, many chemicals)
-Umami/delicious (binding to certain amino acids)
128
What are the pathways that taste uses?
-Sensory impulses from taste receptors cells on the anterior 2/3s of the tongue travel on fibers of the facial nerve
-Impulses from receptors on the posterior 1/3 of the tongue travel on the glossopharyngeal nerve
-Impulses from the receptors at the base of the tongue and the pharynx travel on the vagus nerve
These cranial nerves send impulses into the medulla oblongata->thalamus->gustatory cortex of the cerebrum (insula)
