Test 5 CH 13 & 14 Flashcards
function of pns?
provides link to and from world outside body
function of sensory receptors?
respond to changes in environment; activation results in graded potentials that trigger nerve impulses
What are the 5 Classifications of receptors?
Mechanoreceptors, thermoceptors, photoreceptors, chemoreceptors, nociceptors
What do chemoreceptors respond to?
chemicals, smell. taste, changes in blood chemistry
What do photoreceptors respond to?
light energy ex. retina ..proteins change shape due to the sun
What receptors are responsible for pain?
Nociceptors
What are the 3 location of receptors?
Exteroceptors, interoceptors, and proprioceptors
What structure of nerve ending is found nearly everywhere throughout the body?
Free nerve endings
What stimulus does a modified free nerve ending respond to?
Mechanoreceptors/light pressure slow adapting
Do nociceptors adapt?
no
Where are hair follicle receptors located?
Exteroceptors
What is phasic adaptation?
signal beginning or the end of stimulus
What does tonic receptor do?
sustained response; adapts slowly or not at all…eg. nociceptors
Encapsulated nerves?
easy to stimulate; fiber terminals enclosed in a CT covering
Two types of peripheral nerves
Cranial and spinal nerves
Sensory nerves impulse goes …
toward the CNS
Mixed nerves are..
both sensory and motor fibers mixed with signals going to and from the CNS
motor nerves impulses…
away from the CNS
Most nerves are…
mixed nerves
Are pure sensory nerves rare?
yes
What is the function of the cranial nerves mnemonic?
Some say marry money but my brother says big brains matter more
How many pairs of spinal nerves are there?
31 pairs of mixed nerves
how many cervical nerves?
Thoracic?
Lumbar?
Sacral?
Coccygeal?
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
What does Dorsal Root contain?
contain sensory fibers from sensory neruons in dorsal root ganglion – carry afferent impulses
What does Ventral Root contain?
contains motor fibers from ventral horn motor neurons–fibers innervate skeletal and visceral muscles
what does each spinal nerve branch into?
a mixed ramus/rami
4 areas spinal nerves branch into:
Dorsal Ramus
Ventral Ramus
Meningeal Branch
Rami Communicantes
What is a plexus?
fibers criss cross form interlacing nerve networks; all ventral rami except T1 and T2; each branch contains fibers from several spinal nerves
Cervical Plexus?
innervate skin of neck and ear
Phrenic nerve innervates?
The diaphragm; only motor output to diaphragm—think backpack nerve
Brachial plexus function?
Gives rise to nerves that innervate upper limb
Axillary nerve innervates?
muscles and skin of shoulder
Radial nerve innervates?
posterior skin of limb; extensor forearm muscles
Musculocutaneous nerve innervates?
proximal arm muscles; sensory input from lateral forearm
Ulnar Nerve innervates?
flexor muscle forearm and muscles + skin of hand
Median Nerve innervates?
skin of anterior forearm
Lumbar Plexus innervates?
innervates thigh, abdominal wall..
Femoral nerve innervates?
innervates quads, skin of anterior thigh, and medial surface of leg
LARGEST nerve of lumbar plexus
Obturator Nerve innervates?
passes through obturator foramen to innervate adductor muscle
Sacral Plexus?
serves the buttock and lower limb; pelvic structures and perineum
Sciatic Nerve innervates?
innervates hamstrings, adductor magnus, and most muscles in leg and foot
What is a reflex?
an automatic response to stimuli
What is a visceral refelc?
Activate visceral effectors such as smooth/cardiac muscle and glands…ex blood pressure
Somatic reflexes?
Activate skeletal muscle
Intrinsic Reflex?
Rapid and predictable motor response; unlearned and involuntary; built into our neural anatomy
Acquired Reflex?
reflexes from practice or repitition
What are the components of the reflex arc?
- receptor
- Sensory neuron
- Integration center
- Motor neuron
- Effector
What is the function of a receptor?
responds to a specific stimulus by producing a graded potential
What is the function of sensory neuron?
transmits afferent impulses to the CNS; action potential travels along axon to gray matter of spinal cord or brain
Integration center function?
point of connection between afferent and efferent pathways; monosynaptic is the simplest
Sensory neuron synapses with?
Motor neuron
Motor neuron..
conducts impulses from integration center to effector organ
Effector responds to…
efferent impulse…muscle fibers contract or glands secrete
Is cranial reflex ipsilateral or contralateral?
Ipsilateral
nervous system must receive ….. to coordinate smooth muscle mvmnt
proprioceptor input
length of muscle =
muscle spindles
muscle spindles are the receptors of…
the stretch reflex
noncontractile filaments means lack of…
myofilaments
what is the stimulus of stretch reflex? What is the response?
Stimulus: stretch causes increased rate of impulses to the spinal cord
Response: contracting muscles reduces tension on muscle spindle
What is an example of the stretch reflex?
Knee-jerk reflex
all stretch reflexes are…. and ….
monosynaptic and ipsilateral
what is the stimulus of a tendon reflex?
over-contraction
What is the response of a tendon reflex?
force relaxation
reciprocal reaction of a tendon reflex?
increase tension
are tendon organ proprioceptors?
yes
where are tendon organs located
in tendons close to skeletal muscle; sensory terminals coil between and around collagen
what initiates a flexor reflex?
painful stimulus; causes automatic withdrawal of body due to threatened body part
can brain override the flexor reflex?
yes
what is the crossed-extensor reflex?
occurs with flexor reflexes in weight-bearing limbs-maintains balance
What is the function of the autonomic nervous system?
general visceral motor systems; make adjustments to ensure optimal support, operate via subconscious control; motor neurons innervate smooth and cardiac muscle and glands
What are the divisions of the PNS?
PNS=sensory and motor division
Motor division= somatic nervous system and autonomic nervous system.
Autonomic NS= parasympathetic and sympathetic
What do the somatic and autonomic NS have in common?
Both have motor fibers
How are the somatic and autonomic NS different?
Effectors are different; efferent pathways and ganglia; target organ responds to neurotransmitters
what is the effector of the somatic nervous system?
skeletal muscle
Where is the cell body of the somatic nervous system?
in CNS
are the fibers of the somatic nervous system myelinated or nonmyelinated?
myelinated and thick
effects of the somatic nervous system are always..
stimulatory
ANS uses two….
neuron chain
what is dual innervation?
all visceral organs served by both divisions but cause opposite effects
What maintains homeostasis between the two divisions?
Dynamic Antagonism
What is closer to the effector in the parasympathetic ns?
ganglia
Where are the cell bodies in the cranial part of the the PNS?
in the brain stem
what cranial nerves are in the preganglionic fibers in the cranial part of the PNS?
oculomotor, facial, glossopharyngeal, and vagus nerve
What do Ciliary Ganglia innervate?
smooth muscles of eye
function of preganglionic axons of otic ganglion?
innervate salivary glands
the pterygopalatine and submandibular postganglionic axons within the facial nerve innervate (5)
nasal mucosa, palate, pharynx, lacrimal glands, and salivary glands
what does the sacral part of the PNS serve?
pelvic organs and distal half of large intestine
what is the only cranial nerve that leaves head and neck area?
Vagus nerve
What does rami communicants coontain?
Grey and white matter
Reflex Classifications:
spinal/cranial
monosynaptic/polysynaptic
ipsilateral/contralateral
somatic/visceral
What type of ganglion does the oculomotor nerve have?
Ciliary
What type of ganglion do the facial nerve have?
PTEROGOPALATINE AND SUBMANDIBULAR
What type of ganglia does the vagus nerve have?
terminal ganglia
Are postganglionic neurons myelinated or not myelinated?
NOT myelinated
Cholinergic nerve fibers release:
ACh
Example: somatic motor neuron
Adrenergic nerve fibers release:
Norepinephrine (NE)
Example: sympathetic postganglionic neuron
where are cholinergic receptors located?
somatic effectors, ALL postganglionic neurons, parasympathetic effectors
Adrenergic receptors are sympathetic or parasympathetic?
sympathetic effectors
What are the two types of cholinergic receptors?
nicotinic and muscurinic
Preganglionic neurons have …. axons
short axons
Postganglionic neurons have … axons
long axons
Where does a preganglionic neuron synapse?
always in the ganglion
upon entering the sympathetic trunk, what may a short preganglionic fiber do?
- Synapse with the ganglionic neuron in same trunk ganglion
- Ascend or descend the sympathetic trunk to synapse in another trunk ganglion
- Pass through trunk ganglion and emerge without synapsing
What is a cholinergic fiber and adrenergic fiber examples of?
Neurotransmitters
Postganglionic cholinergic axons have …. axons ONLY
parasympathetic
Nicotinic receptors are found on all…
postganglionic neurons (sympathetic and parasympathetic)
Muscuranic receptors found on…
all effector cells stimulated by postganglionic cholinergic fibers
What are the two major classes of adrenergic receptors?
Alpha and Beta
What are A1 and B1 responsible for?
Activation and Excitation
What are A2 and B2 responsible for?
Inhibit and Relax
What is a kinase?
An enzyme that transfers a phosphate group from ATP to a specific substance;
Ability to turn enzymes on or off
What is phosphorylation?
the attachment of a phosphate group to a molecule
Used to activate or deactivate enzymes
ATP broken down is =
ADP + P= ATP
A1 function?
blood vessel constriction
A2 function?
inhibits insulin secretion
B1 function?
increase insulin secretion
B2 function?
dilates blood vessels, relaxes smooth muscles of GI tract
B3 receptors are only found where?
in adipose tissue of animals that hibernate
What does Atropin do to body?
relaxes muscle tone and blocks muscunaric ACh receptors
Example: dilating pupils at eye doctor
Function of Neostigmine?
Inhibits Acetylcholinesterase—ACh lingers
prevents breakdown of ACh
Used to treat myasthenia gravis
Function of Sympathomimetics?
sympathetic mimiking drugs; stimulate A1 adrenergic receptors to constrict blood vessels in nasal mucosa
inhibits secretion of mucus
example: epinephrine
Beta-Antagonists function?
drugs that attach to B2 receptors to dilate lung bronchioles in asthmatics—relaxes muscle back to normal
Beta-Blockers function?
drugs attach to B1 receptors to prevent their activation;
Avoid excitement and stage fright, calm heart beat and circulation
