Chapter 13 & 14

Question 0

Peripheral Nervous System

Answer 0

Provides links from and to world outside body. PNS is the part of the nervous system that consists of the nerves and ganglia (a nerve cell cluster) outside of the brain and spinal cord. Sensory receptors, peripheral nerve endings, efferent motor endings (carry nerve impulses AWAY from the central nervous system to effectors such as muscles or glands).

Question 1

Sensory receptors

Answer 1

specialized to respond to changes in environment (stimuli), activation results in graded potentials that trigger nerve impulses.

Question 2

Sensation

Answer 2

awareness of stimuli. the awareness of changes in the internal and external environment.

Question 3

Perception

Answer 3

interpretation of meaning of stimulus

Question 4

Classification of receptors

Answer 4

based on

• type of stimulus they detect
• location in body

Question 5

Mechanoresceptros

Answer 5

respond to touch, pressure, vibration and stretch

Question 6

thermoreceptors

Answer 6

sensitive to changes in temperature

Question 7

photoreceptors

Answer 7

respond to light energy (e.g. retina)

Question 8

chemoreceptors

Answer 8

respond to chemicals (smell, taste, changes in blood chemistry)

Question 9

nociceptors

Answer 9

sensitive to pain-causing stimuli (extreme heat or cold, excessive pressure, inflammatory chemicals)

Question 10

Exteroceptors (location sensory receptors)

Answer 10

respond to stimuli arising outside of body, receptors in skin for touch, pressure, pain and temperature. Most special sense organs.

Question 11

Interoceptors (Location of sensory receptor)

Answer 11

respond to stimuli arising in internal viscera and blood vessels. Sensitive to chemical changes, tissue stretch and temperature changes. Sometimes cause discomfort but usually unaware of their workings.

Question 12

Proprioceptors (Location of sensory receptor)

Answer 12

respond to stretch in skeletal muscles, tendons, joints, ligaments and connective tissue coverings of bones and muscles. Inform brain of one’s movements

Question 13

tactile corpuscles

Answer 13

dicriminative touch

Question 14

lamellar corpuscles

Answer 14

deep pressure and vibration

Question 15

bulbous corpuscles

Answer 15

deep continuous pressure

Question 16

muscle spindles

Answer 16

muscle strech

Question 17

Sensation

Answer 17

the awareness of changes in the internal and external environment

Question 18

perception

Answer 18

the conscious interpretation of those stimuli

Question 19

Levels of neural integration in sensory systems:

Answer 19

receptor level: sensory receptors reside
circuit level: processing in ascending pathways
Perceptual level-processing in cortical sensory areas

Question 20

Processing at the 3 levels

Answer 20

Level one: Stimulus -> Graded potential/generator potential in afferent neuron ->action potential

Level two: Conduction of sensory impulses upward (first, second, third order sensory neurons

Level three: interpretation of input base on location of target neurons in sensory cortex

Question 21

Perceptual detection

Answer 21

ability to detect a stimulus has occurred

Question 22

Magnitude estimation

Answer 22

ability to detect how intense stimulus is

Question 23

Spatial descrimination

Answer 23

identify the site or patter of stimulation (two-point discrimination)

Question 24

Feature abstraction

Answer 24

mechanism for which a neuron/circuit is tuned to one feature of a stimulus in preference to another.

Question 25

Perception of Pain

Answer 25

warns of actual or impending tissue damage. Stimuli include extreme pressure and temperature, histamine K+, ATP, acids and Bradykinin. Impulses travel on fibers that reales neurotransmitters glutamate and substance P. In times of danger, some pain impulses are blocked by in endogenous opioids.

Question 26

Visceral Pain

Answer 26

stimulation of visceral organ receptors. Felt as vague aching, gnawing, burning. activated by tissue stretching, ischemia, chemicals, muscle spasms

Question 27

Referred pain

Answer 27

pain from one body region but perceived from a different region. (left arm pain during a heart attack.)

Question 28

Structure of the Nerve

Answer 28

cordlike organ of the PNS. Axon wrapped in myelin sheath. Each nerve is wrapped in endoneurium. Bundles of endoneurium, fascicles, wrapped in perineurium.

Question 29

Ganglia

Answer 29

Contain neuron cell bodies associated with nerves in PNS. Ganglia associated with afferent nerve fibers contain cell bodies of sensory neurons. Ganglia associated with efferent nerve fibers contain autonomic motor neurons.

Question 30

Regeneration of nerve fibers

Answer 30

Mature neurons are amitotic (related to the division of a cell nucleus into two parts by constriction) but if soma of damaged nerve is intact, peripheral axon may regenerate. Greater distance betwen severed ends-less change of regeneration. Most CNS fibers never regenerate, CNS oligodendrocytes bear growth-inhibiting proteins that prevent CNS fiber regeneration

Question 31

Spinal nerves

Answer 31

31 pairs of mixed nerves named for point of issue from spinal cord. Supply all body parts but head and part of neck. 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal.

Question 32

Ventral Roots

Answer 32

Contain Motor (efferent) fibers from ventral horn motor neurons

Question 33

Dorsal Roots

Answer 33

Contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia and conduct impulses from peripheral recpetors

Question 34

Sacral Plexus

Answer 34

arises from L4-S4, serves the buttock, lower limb, pelvic structures and perineum. Sciatic nerve resides in the sacral plexus-longest and thickest nerve of body, innervates hamstring muscles, adductor magnus, and most muscles in leg and foot, composed of two nerves: tibial and common fibular.

Question 35

Dermatome

Answer 35

area of skin innervated by cutaneous branches of single spinal nerve. All spinal nerves except for C1 participate in dermatomes. extent of spinal cord injuries ascertained from dermatomes. Most dermatomes overlap, so destruction of a single spinal nerve will not cause complete numbness.

Question 36

Reflex activity

Answer 36

Inborn reflex- rapid, involuntary, predictable motor response to stimulus Learned reflexes- result from practice or repetition. example- driving skills

Question 37

somatic reflexes

Answer 37

activation of skeletal muscle

Question 38

autonomic reflexes

Answer 38

activate visceral effectors (smooth or cardiac muscle or glands)

Question 39

Spinal somatic reflexes

Answer 39

integration center in spinal cord. Effectors are skeletal muscle. Testing of somatic reflexes important clinically to assess condition of nervous system

Question 40

Stretch and Tendon reflexes

Answer 40

to smoothly coordinate skeletal muscle, nervous system must receive proprioceptor input regarding; length of muscle-from muscle spindles amount of tension in muscle-from tendon organs

Question 41

the stretch reflex

Answer 41

maintains muscle tone in large postural muscles. How stretch reflex works: ->stretch activates muscle spindle -> sensory neurons synapse directly with a motor .........

Question 42

The tendon reflex

Answer 42

polysynaptic reflexes. helps prevent damage due to excessive stretch. important for smooth onset and termination of muscle contraction. Produce muscle relaxation (lengthening) in response to tension.

Question 43

Reflexes to know (4)

Answer 43

stretch, cross-extensors, tendon, flexor

Question 44

Crossed extensor reflex

Answer 44

occurs with flexor reflexes in weight-bearing limbs to maintain balance.

Question 45

Autonomic Nervous system

Answer 45

consists of motor neurons that innervate smooth and cardiac muscle and glands. Makes adjustments to ensure optimal support for body activities. Operate via subconscious control. also called involuntary nervous system or general visceral motor system. one part of the PNS, the other part is the somatic nervous system. involuntary actions such as breathing and digestion

Question 46

Somatic versus autonomic nervous systems

Answer 46

both have motor fibers. Differ in effector organs, efferent pathways.....

Question 47

effector in somatic nervous system

Answer 47

skeletal muscle

Question 48

effector in sympathetic nervous system

Answer 48

organs

Question 49

effector in parasympathetic nervous system

Answer 49

organs

Question 50

Role of the parasympathetci division

Answer 50

promotes maintenance activities and conserves body energy. Directs digestion, diuresis, defecation. As in person relaxing and reading after a meal. Blood pressure, heart rate and respiratory rates are low

Question 51

role of sympathetic division

Answer 51

mobilizes body during activity; fight or flight system. Exercise, excitement, emergency, embarrassment. Increased heart rate; dry mouth; cold, sweaty skin; dilated pupils

Question 52

Parasympathetic (crainosacral) division

Answer 52

long preganglionic fivers from brain stem and sacrum. Extend from CNS almost to target organs. Synapse with postganglionic neurons in terminal ganglia close to/within target organs. Short postganglionic fibers synapse with effectors.

Question 53

Cholinergic receptors

Answer 53

2 types of recpetors bind ACh ->nicotinic, muscarinic. Names after drugs that bind them and mimic ACh effects.

Question 54

Control of the ANS function

Answer 54

hypothalamus-main integrative center of ANS activity. Subconscious cerebral input via limbic system structures on hypothalamic centers

Question 55

Hypertension (high blood pressure)

Answer 55

overactive sympathetic vasoconstrictor response to stress. Treated with adrenergic receptor-blocking drugs

Question 56

Autonomic dysreflexia

Answer 56

uncontrolled activation of autonomic neurons in quadriplegics and those with spinal cord injuries above T6. Blood pressure skyrockets. Life-threatening.

Question 57

General structure of a spinal nerve

Answer 57

Each spinal nerve connects to spinal cord viw two roots->ventral roots and dorsal roots.

Question 58

Rami

Answer 58

each spinal nerves branched into mixed rami (dorsal ramus and ventral ramus)

Question 59

Cervical Plexus

Answer 59

in neck, C1-C5. Supplies neck and phrenic nerve to the diaphragm.

Question 60

Brachial Plexus

Answer 60

in armpit, C5 to T1. Supplies upper limb and some shoulder/neck.

Question 61

Lumbar plexus

Answer 61

In lower back, L1 to L4. Supples abdominal wall, anterior thigh and genitalia.

Question 62

Plexus

Answer 62

a network of nerves or vessels in the body.

Question 63

Components of a reflex arc

Answer 63

1. Receptor 2. sensory neuron 3. integration center 4. motor neuron 5. effector

Question 64

Flexor reflex

Answer 64

a spinal reflex in which a painful (pressure) stimulus applied to a toe, results in a flexion, or withdrawal, of the leg. Also called withdrawal reflex.