Anatomy & Physiology (LAB 8b & 9) - PNS & Skin Sensory Receptors, Olfaction, & Gustation

cervical nerves

C1-C8 (8 pair)

thoracic nerves

T1-T12 (12 pair)

lumbar nerves

L1-L5 (5 pair)

sacral nerves

S1-S5 (5 pair)

coccygeal nerves

Co1 (1 pair)

cervical plexus

C1-C4

major nerve: phrenic nerve

brachial plexus

C5-T1

major nerves: “rum in the am”

lumbar plexus

L1-L4

major nerves: ilioinguinal, obturator, femoral, genitofemoral

sacral plexus

L5-S4

dermatomes

area of skin supplied w/ sensory innervation by particular pair of spinal nerves

reflexes

rapid, predictable, involuntary motor responses to stimuli

autonomic reflexes

not under conscious control; activate smooth muscles, cardiac muscle, & glands; regulate digestion, BP, & salivation

somatic reflexes

stimulation of skeletal muscles & withdrawal response

motor tracts

sensory tracts

dorsal root ganglion

dorsal horn

lateral horn

ventral horn

dorsal funiculus

lateral funiculus

ventral funiculus

central canal

ventral median fissure

dorsal median sulcus

afferent neuron

carries sensory action potential from receptor to CNS

efferent neuron

carries motor action potentials from integration center to effector organ

control/integration center

single/multiple synapses bw sensory & motor neurons; always in CNS

exteroceptors

located on surface of body & respond to external stimuli

interoceptors

located internally, respond to internal stimuli (temp, stretching, & chem level changes)

proprioceptors

located in skeletal muscles, tendons, ligaments, & CT coverings; respond to being stretched and send messages to brain about movements & position (“aware” of position & movement)

mechanoreceptors

stimulated by mechanical force (stretch, vibration, pressure, itch)

thermoreceptors

respond to temperature changes

photoreceptors

respond to light (retina)

chemoreceptors

stimulated by chemicals/chemical level changes, special senses of smell & taste

osmoreceptors

detect chemistry of blood (pH, CO₂ , O₂ )

nocireceptors

pain receptors, respond to tissue damage

gustation

taste buds are main taste sense organs

fungiform

“mushroom-shaped”, scattered all over surface of tongue & contain most of taste buds

circumvallate

“round shaped”, largest, but least numerous of papillae, found near back of tongue & arranged in V shape

filiform

“filamentous”, mechanical function (no taste buds)

supportive cells

form bulk of taste bud & help insulate & support the other cells

gustatory cells (taste cells)

respond to food chemical stimulants, their microvilli (gustatory hairs) are sensitive & extend into taste pores on tongue

basal cells (stem cells)

divide & differentiate into new gustatory cells, important since taste buds cells are subjected to friction & burning, replaces taste cells in 1 week

salty

due to metals/salts Na⁺

sour

due to acids H⁺

sweet

due to organic substances (sugars, alcohols)

bitter

due to alkaloids

umami

elicited by amino acids-glutamate; responsible for beefy taste of beef & tanginess of aged cheese

olfaction

smell

olfactory cells

specialized chemoreceptors which react to ordorants

pathway 1

thru thalamus to piriform of olfactory fortex & uncus of temporal lobes

pathway 2

subcortical limbic system (hypothalamus & amygdala) - trigger emotions & memories

olfaction tests

sniff aromatic volatile substance (coffee, vanilla, lavender)

gustation tests

sweet, sour, salty, & bitter tests

segmental branches

hypoglossal nerve (12)

lesser occipital nerve

greater auricular nerve

transverse cervical nerve

ansa cervicalis

accessory nerve (11)

phrenic nerve

supraclavicular nerves

axillary nerve

radial nerve

musculocutaneous nerve

ulnar nerve

median nerve

iliohypogastric

ilioinguinal

genitofemoral

lateral femoral cutaneous

obturator

femoral

lumbosacral trunk

iliohypogastric

ilioinguinal

femoral

lateral femoral cutaneous

obturator

anterior femoral cutaneous

saphenous

superior gluteal

inferior gluteal

pudendal

sciatic

posterior femoral cutaneous

common fibular

tibial nerve

sural (cut)

deep fibular

superficial fibular

plantar branches

superior gluteal

lumbosacral trunk

inferior gluteal

common fibular

tibial

posterior femoral cutaneous