nervous system PNS and special senses

Question 1

the anatomy of peripheral nerves (PNS nerves)

Answer 1

they are structures that contain bundles of neuronal axons, blood vessels and connective tissue layers.

Question 2

features of cranial nerves

Answer 2

some nerves have only sensory or only motor neurons
innervate head and neck only
12 pairs

Question 3

features of spinal nerves

Answer 3

innervate neck and body 
contain dorsal root ganglia 
all nerves contain sensory and motor neurons 
nerves form intricate nerve plexuses 
31 pairs

Question 4

dorsal (posterior) root in spinal cord

Answer 4

contains axons of incoming sensory neurons.

Question 5

ventral (anterior) root

Answer 5

contains the axons of the outgoing motor neurons

Question 6

what is a dorsal root ganglion

Answer 6

a swelling on the dorsal root where all the cell bodies of the sensory neurons sit

Question 7

what is sensory division of the PNS

Answer 7

a major division in the PNS, it includes all of the sensory receptors and the sensory nerves carrying information to the CNS

Question 8

what are sensory receptors

Answer 8

they are on the receptive region of the primary sensory neurons

Question 9

exteroceptors (sensory receptor)

Answer 9

all sensory receptors located near the surface of the body and within the special sense organs. they respond to stimuli from the external environment

Question 10

proprioceptors (sensory receptors)

Answer 10

all sensory receptors located within the skeletal muscles, tendons, ligaments and joints. they respond to stimuli related to the activities of these structures such as movement and changes in position

Question 11

interoceptors (sensory receptor)

Answer 11

all the sensory receptors located in or near the viscera (smooth muscle, cardiac muscle and glands) of the body. they respond to stimuli within the internal environment of the body.

Question 12

what do chemoreceptors respond to

Answer 12

chemicals or changes in chemical concentrations

Question 13

what do thermoreceptors respond to

Answer 13

to changes in temperature

Question 14

what do nociceptors respond to

Answer 14

to harmful or potentially harmful stimuli

Question 15

what do photoreceptors respond to

Answer 15

to light waves

Question 16

what do mechanoreceptors respond to

Answer 16

to stimuli that distort the plasma membrane e.g. stretch, compression, touch, vibration etc.

Question 17

what are primary sensory neurons

Answer 17

they are afferent (conducting) neurons that carry nerve signals from sensory receptors to the CNS.

Question 18

what kind of neuron is a primary sensory neuron

Answer 18

it is a unipolar neuron. their cell bodies reside in the dorsal root ganglia of spinal nerves and their axon terminals terminate in the spinal cord or brainstem.

Question 19

PNS to CNS interaction

Answer 19

the CNS recieves thousands of afferent signals from the PNS sensory neurons every minute. each primary sensory neuron has a specific type of sensory receptor, located in a particular part of the body which follows a specific pathway to a specific region of the brain. this way the brain is able to distinguish the type of stimulus and the location of that stimulus. the greater the frequency, the stronger the stimulus (strength, pattern and duration)

Question 20

what is the functionalities of lower motor neurons

Answer 20

lower motor neurons receive innervation from upper motor neurons under voluntary control.

Question 21

what is the anatomy and functionalities of motor units

Answer 21

a motor unit is one lower motor neuron and all the muscle fibers it innervates. the anatomy of a motor unit is a muscle made up of lots of muscle fibers

Question 22

what is the somatic nervous system

Answer 22

one of 2 subdivisions of the motor division of the PNS. The somatic nervous system consists of all the motor neurons that innervate skeletal muscles. somatic motor neurons are referred to as lower motor neurons.
it is voluntary movement

Question 23

what does the strength of the muscle contraction depend on

Answer 23

frequency- the greater the frequency the stronger the contractions
recruitment- the number of motor units stimulated. the greater number recruited, the more muscle fibers being stimulated to contract and therefore greater overall strength of the muscle contraction.

Question 24

what is a somatic motor reflex

Answer 24

they are involuntary movements of skeletal muscles in response to particular sensory stimuli. CNS integration of these movements occurs within the spinal cord or brainstem

Question 25

what is a reflex arc

Answer 25

how somatic reflexes occur. it is the involuntary movements of skeletal muscles in response to particular sensory stimuli. 1. sensory receptor 2. sensory neuron 3. integration system 4. motor system 5. effector

Question 26

what is the autonomic nervous system

Answer 26

it is a subdivision of motor division (the other is somatic nervous system). it is composed of neurons that innervate the viscera of the body. ANS motor neurons work under involuntary control directed mostly by the hypothalamus and brainstem, also involving cerebral cortex, limbic system and spinal cord. ANS control is through autonomic reflexes.

Question 27

what are autonomic reflexes

Answer 27

just like somatic reflexes. it has an arc where sensory neurons communicate directly with autonomic motor neurons in the brainstem, or spinal cord

Question 28

characteristics of sympathetic system

Answer 28

active when anxious or nervous, flight or fight system, high energy use, prepares body for action, heart rate increases, pupils dilate, blood vessels dilate

Question 29

characteristics of parasympathetic system

Answer 29

active when reading a book, facilitates housekeeping functions, low energy use, rest and digest system, pupils constrict, heart rate is low

Question 30

both parasympathetic and sympathetic pathways have what

Answer 30

a two neuron relay from the spinal cord to the viscera (organ). they have preganglionic neuron and a postganglionic neuron that synapse with each other in the ganglia outside the spinal cord.

Question 31

what are the differences between parasympathetic and sympathetic pathways

Answer 31

- they differ by the effect they have on the viscera - the spinal cord level where their preganglionic neurons exit - the location of their associated ganglia - the length of their 2 neurons - the neurotransmitters they release at the viscera.

Question 32

parasympathetic nervous system neurons

Answer 32

preganglionic neurons exit at the CNS via the cranial and sacral nerves. ganglia is located in or near the viscera (preganglionic neurons are long and postganglionic neurons are short) the postganglionic neurons release Ach which may be excitatiry or inhibitory depending on the type of effector containing the muscarinic receptors

Question 33

sympathetic nervous system neurons

Answer 33

preganglionic neurons exit the CNS via thoracic and lumbar nerves. ganglia is located in a chain alongside the spinal cord (preganglionic neurons are short and postganglionic neurons are long) postganglionic neurons release epinephrine (NE) which may be excitatory or inhibitory depending on the subtype of adrenergic receptors in the viscera

Question 34

physiological effects of the sympathetic pathway

Answer 34

pupils dilate, increased heart rate, sweating, increased blood sugar levels, increased blood flow to skin

Question 35

physiological effects of the parasympathetic pathways

Answer 35

pupils constrict, decreased heart rate, crying, erection, increased urine production, increase blood flow to digestive system

Question 36

what are special senses

Answer 36

refers to the groups of sensory receptors located within the specialised organs of the head and neck that respond to very particular types of external stimuli

Question 37

vision sensory receptors and where they are found

Answer 37

occurs via detection of light by light receptors called photoreceptors. photoreceptors are located in the retina of the eye. the 2 types of photoreceptors are - cones; provide high- acuity colour vision - rodes; allows peripheral vision.

Question 38

functions of eye structures | cornea, sclera, choroid, iris, lens, cilary body, retina

Answer 38

cornea- allowing light in and bending it sclera- protection and muscle attachment choriod- absorbs light and distributes blood supply iris- controlling diameter of the pupil lens- refracts light to focus it on retina cilary body- holds the lens in place and alters the shape of the lens and produces aqueous humour retina- containing the photoreceptors

Question 39

hearing receptors and where they are found

Answer 39

they are specialized hair cells, responding to mechanical stimuli that are in the cochlea of the inner ear.

Question 40

equilibrium receptors and where they are found

Answer 40

they are specialized mechanoreceptor hair cells found in the vestibule and semicircular canals (the inner ear)

Question 41

functions of ear structures | auricle, ear canal, ear drum, auditory ossicles, auditory tube, vestibule, semicircular canals, cochlea

Answer 41

auricle- collects and funnels sound waves ear canal- transmits sound waves to the tympanic membrane ear drum- vibrates when hit by sound waves, transmitting vibrations to the ossicles auditory ossicles- transmit vibrations to the inner ear auditory tube- allow equalisation of pressure on either side of the tympanic membrane vestibule- containing fluid and receptors for equilibrium semicircular canals- fluid filled canals containing receptors for equilibrium cochlea- fluid filled canal containing the receptors for hearing

Question 42

taste receptors and where they are found

Answer 42

taste occurs via the detection of dissolved chemicals in food or drink by gustatory chemoreceptors in taste buds. taste buds are located on the tongue, cheeks, soft palate, pharynx and epiglottis.

Question 43

the taste buds consist of 3 types of cells

Answer 43

basal cells- stem cells which can differentiate into supporting cells supporting cells- surround and support gustatory cells. they are the precursor to gustatory cells gustatory cells- they contain microvilli that pick up chemicals dissolved in saliva which stimulate chemoreceptors on the cell

Question 44

what are the 5 basic taste sensations

Answer 44

sweet- sugars, alcohol and some amino acids sour- acids salty- metal ions bitter- alkaloids, and some specific non alkaloids umami- amino acids glutamate and aspartate

Question 45

what is the receptor for smell and where is it found

Answer 45

olfactory receptors a type of chemoreceptor found within the olfactory epithelium on the roof of the nasal cavity.

Question 46

neurons of the sympathetic nervous system arise from the _____ region of the spinal cord while neurons from the parasympathetic nervous system arise from the _____ region. despite this, both divisions innervate the same viscera, but generally have the ____ effects on the viscera

Answer 46

1. thoracolumbar 2. craniosacral 3. same 4. opposite

Question 47

order the structure within a nerve from superficial to deep

Answer 47

1. epineurium tissue 2. perineurium tissue 3. endoneurium tissue 4. myelin 5. axon