Exam 4 Nervous

bipolar layer (retina)

(Middle layer)

rods and cones (retina)

(Next to choroid)

ganglionic layer (retina)

(Next to vitreous humor)

meninges (brain models)

- 3 specialized membranes surrounding spinal cord and brain - functions: 1. phys stability 2. shock absorption 3. carry blood supply (oxygen and nutrients)

meninges (spinal cord model)

- 3 specialized membranes surrounding spinal cord and brain - functions: 1. phys stability 2. shock absorption 3. carry blood supply (oxygen and nutrients)

vestibulocochlear (cranial nerve function)

- ONLY sensory - special sensory: hearing and balance - 2 branches 1. vestibular (balance) 2. cochlear (hearing)

PNS neuroglia

- SEULE two types - Schwann cells - satellite cells

reticular activating system (RAS)

- a dense network of neurons found in the core of the brain stem; it arouses the cortex and screens incoming information - not work = unconscious

continuous propagation

- action potential appears to move step by step through entire axon - in unmyelinated axons - slower

dermatome

- area of skin innervated by a spinal nerve - not face (CN V trigeminal) or scalp - some boundaries overlap

visceral reflexes

- autonomic reflexes - control involuntary effectors (smooth, cardiac, glands, adipose)

unmyelinated axons

- axons w/o myelin sheath - CNS gray matter - cell bodies, dendrites - continuous nonmyelinating scwhann cells, lack of nodes of ranvier

astrocytes

- blood-brain barrier - maintain ion, nutrient, gas concentrations - take up excess neurotransmitters - produce scar tissue that can block axon growth in damaged area - release chemicals that block axon regrowth - CNS neuroglia cell

inferior colliculi (brain models)

- bottom bump - reflex of head and neck in response to auditory stimulus

subarachnoid space (spinal cord model)

- btn arachnoid mater and pia mater - cerebrospinal fluid (shock absorber, diffusion of gases, nutrients, etc) - blood vessels for spinal cord

epidural space

- btn dura mater and vertebrae

ventricles

- chambers formed by neural tube expansion during dvlpmt - filled with CSF; lined by ependymal cells - protect brain and spinal cord (mechanical protection, homeostasis, circulation)

microglia

- clear cell debris, waste products - engulf invading microbes - CNS neuroglia cell

brainstem (brain models)

- comprised of the midbrain, pons, and medulla oblongata - connects spinal cord to thalamus

infundibulum (brain models)

- connects hypothalamus to pituitary gland

central canal (spinal cord slide)

- contains cerebrospinal fluid

spinal reflexes

- controlled in the spinal cord - no brain input - control some of your most rapid reactions to environmental changes

cerebellum (brain models)

- coordinate complex movements - maintain normal muscle tone - regulate posture, balance - fine tuning movements (conscious and subconscious)

saltatory propagation

- depolarizes only at nodes - in myelinated axons - faster - speed varies with axon diameter

hypothalamus (brain models)

- emotions - autonomic function - hormone production - part of diencephalon - major homeostasis regulator (ANS controller) - stimulated by sensory info, changes in CSF, and chemicals in blood

pineal gland (brain models)

- endocrine structure - secretes melatonin - regulates day-night cycle and reproductive functions

prefrontal cortex

- from sensory association areas - performs intellectual functions

Excitatory postsynaptic potential (EPSP)

- graded depolarization - shifts membrane potential closer to threshold

inhibitory postsynaptic potential (IPSP)

- graded hyperpolarization - shifts membrane potential farther away from threshold

myelinated axons

- have myelin sheaths - created by Schwann cells - CNS white matter

auditory cortex

- hearing - primary auditory cortex (monitors auditory info) - auditory association area (recognizes different sounds (such as speech))

summation

- integration of effects of graded potentials - collective effects of both EPSPs and IPSPs - net effect may be no change in membrane potential

chemical synapse

- most abundant type of synapse - neurotransmitter - cholinergic synapses (ACh)

cholinergic synapses

- most common - release acetylcholine - chem'l synapse

gray matter (spinal cord model)

- mostly neuron cell bodies, neuroglia, unmyelinated axons - site for integration of postsynaptic potentials (IPSPs and EPSPs)

Broca's area

- motor speech area - speech production

cervical plexus (flat man nerve model)

- neck and diaphragm - anterior rami of spinal nerves C1-C5 - phrenic nerve

cauda equina

- nerve roots from spinal cord to lower intervertebral foramen to exit - L2-S5 and filum terminale

Schwann cells

- neurolemmocytes - cover peripheral axons - produce myelin - a single Schwann cell wraps a single internode - PNS neuroglia

electrical synapses

- only between neurons - gap junctions - synchronization of neurons - rare

nociceptors

- pain receptors - free nerve endings with large receptive fields and broad sensitivity - do not adapt quickly

brachial plexus (flat man nerve model)

- pectoral girdle, upper limb - anterior rami of C5-T1 - innervates skin/muscles of pectoral girdle, upper back, and upper limbs

sacral plexus (flat man nerve model)

- pelvic girdle, lower limb - anterior rami L4-S4 - innervate skin and muscles of lower trunk, pelvic girdle, lower limbs

lumbar plexus (flat man nerve model)

- pelvic girdle, lower limb - anterior rami T12-L4 - innervate skin and muscles of lower trunk, pelvic girdle, lower limbs

filum terminale

- pia mater - anchor spinal cord to S2

hypoglossal (cranial nerve function)

- primarily motor - somatic motor: muscs of tongue

accessory (cranial nerve function)

- primarily motor - somatic motor: trapezius, sternocleidomastoid, some muscles of pharynx

sensory cortex

- primary somatosensory cortex (receives sense info) - somatosensory association area (recognizes different sensations)

cranial reflexes

- processing occurs in brain

spinal reflexes are

- processing occurs in spinal cord only - 1+ spinal cord levels

ependymal cells

- produce cerebrospinal fluid - lines central canal (spine) and ventricles (brain) - CNS neuroglia cell

integrative centers

- receive info frm association areas - direct motor activities - perform analytical functions - in lobes/cortical areas of both cerebral hemispheres - language areas typically left hemisphere

interneurons

- receive info from PNS and CNS - responsible for higher functions (mem, learning)

interoceptors sensory receptor type

- receptors in blood vessels, visceral organs - info about internal environment

exteroceptors sensory receptor type

- receptors on or near body surface - info abt external environ

medulla oblongata (brain models)

- relays sensory info from brainstem to the thalamus - all ascending and descending tracts - cardiovascular center (rate, force of heartbeat, blood vessel diameter) - respiratory center (breathing, reflexes of vomiting, coughing, sneezing) - nuclei for CN VIII-XII - contains autonomic centers for vital functions

locomotion

- repetitive, coordinated actions of several muscle groups - neurons controlling flexor and extensor muscles

red nucleus

- rich in blood supply - subconscious motor commands to upper limbs to maintain muscle tone

epithalamus

- roof of diencephalon; superior to third ventricle - contains extensice choroid plexus that extends through interventricular foramina

motor neurons

- sends signals from CNS to muscs and glands

thalamus (brain models)

- sensory relay/processing for everything coming up from spinal cord - part of diencephalon - receives sensory info, integrates it, sends it to cerebral cortex - major role in cogniion (awareness, knowledge acquisition) - role in emotions and mem

somatic motor neurons

- skeletal muscles - cell body lies in CNS

olfactory cortex

- smell

visceral motor neurons

- smooth muscle, cardiac muscle, glands, adipose tissue - CNS and PNS - cell bodies in autonomic ganglia

abducens (cranial nerve function)

- somatic motor (1 extrinsic eye muscle) - general sensory (proprioception)

trochlear (cranial nerve function)

- somatic motor (1 extrinsic eye muscle) - general sensory (proprioception)

oculomotor (cranial nerve function)

- somatic motor (4 extrinsic eye muscles) - autonomic motor (smooth muscle: iris pupil diameter, ciliary body lens shape) - general sensory (proprioception)

facial (cranial nerve function)

- special sensory: taste - general sensory: external ear, proprioception - somatic motor: muscles of facial expression - autonomic motor: salivary and lacrimal glands

glossopharyngeal (cranial nerve function)

- special sensory: taste - general sensory: middle ear - somatic motor: muscles of pharynx - autonomic motor: parotid gland

vagus (cranial nerve function)

- special sensory: taste from base of tongue, epiglottis, pharynx - general sensory: proprioception from pharynx - visceral sensory: stretch and chemoreception - somatic motor: muscles of throat and neck - autonomic motor: smooth musc, cardiac msuc

corpora quadrigemina (brain models)

- startle reflex

diencephalon

- structural/functional link btn cerebral hemispheres and rest of CNS - two parts: thalamus and hypothalamus

oligodendrocytes

- supp fibers w/n CNS - produce myelin - CNS neuroglia cell

neuroglia

- supp, protect, nourish neurons - 1/2 the total vol of nervous sys - undergo cell division in mature nervous sys

satellite cell

- surround peripheral cell bodies - regulate environment around neurons - PNS neuroglia

gustatory cortex

- taste

cerebral cortex

- thin superficial layer of gray matter - major cortical functions (conscious thought, mem storage and processing, sensory processing, control of skele muscs)

free nerve endings

- tips of branching dendrites of sensory neurons - simplest receptors - respond to many different stimuli, so not much receptor specificity

superior colliculi (brain models)

- top bump - visual info frm thalamus, manages reflex from our eyes and head and neck

dura mater (spinal cord model)

- toughest and most durable - collagen fibers (str and flexibility)

dura mater (brain models)

- toughest and most durable - collagen fibers (str and flexibility) - involved in separating sections of the brain (L/R cerbrum and L/R cerebellum)

olfactory (cranial nerve function)

- tract, not true nerve - cribriform plate - purely sensory - smell

optic (cranial nerve function)

- tract, not true nerve - from retina - optic foramen - purely sensory

pons (brain models)

- tracts and relay centers for bringing up info to thalamus for processing - 4 groups of structures: 1. ascending, descending, and transverse tracts 2. nuclei controlling respiration 3. CN V-VIII 4. nuclei/tracts that process/relay info sent to/frm cerebellum

shingles

- varicella-zoster virus (VZV) herpes virus; causes chickenpox and shingles - attacks neurons in posterior roots and sensory ganglia

visual cortex

- vision - primary visual cortex (visual info from lateral geniculate bodies) - visual association area (interprets the info)

midbrain (brain models)

- visual and auditory processing - direct complex motor patterns - influ lvl of activity in entire nervous sys

motor cortex

- voluntary - primary motor cortex (directs voluntary movement) - premotor cortex (coordinates learned movements)

lumbar puncture (spinal tap)

- withdraw sample of cerebrospinal fluid - needle inserted into subarachnoid space, lumbar region, below conus medullaris to avoid spinal cord

polysynaptic reflexes

-More complex neural pathway -More than one synapse involving interneurons within the reflex arc - 1+ interneuron

monosynaptic reflexes

-single synapse- simplest reflex arcs -sensory neuron synapses directly with motor neuron (no interneuron) -fast response - not very common

How many coccygeal spinal cord segments?

1

4 major nerve plexuses

1. cervical 2. brachial 3. lumbar 4. sacral

Classification of reflexes into 4 classes

1. development of reflexes (innate, acquired) 2. nature of response (somatic, visceral) 3. complexity of circuit (monosynaptic, polysynaptic) 4. processing site (spinal, cranial)

6 functional categories of the cerebral cortex

1. motor 2. sensory 3. visual 4. auditory 5. olfactory 6. gustatory

How many thoracic spinal cord segments?

12

spinal cord # of segments

31 (8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal)

How many lumbar spinal cord segments?

5

How many sacral spinal cord segments?

5

How many cervical spinal cord segments?

8

myelin

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

relative refractory period

A period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual

unipolar neuron

CNS to PNS

multipolar neuron

CNS to motor neurons

denticulate ligaments

Specializations of the pia mater that anchor the spinal cord to the dura mater and limit the movement of the cord (prevent lateral movement)

absolute refractory period

The minimum length of time after an action potential during which another action potential cannot begin.

trigeminal (cranial nerve function)

V1. ophthalmic (general sensory: upper eyelid, forehead, scalp) V2. maxillary (general sensory: skin of cheek, nose, upper dentition) V3: mandibular (somatic motor: muscles of mastication; general sensory: mandible area, lower dentition, proprioception)

propagation

action potential at one site triggers action potential at adjacent site; process continues to end of axon

receptive field

area monitored by single receptor cell

innate reflexes

basic neural reflexes formed before birth

conduction

carry information up and down spinal cord

conus medullaris

cone shaped end of spinal cord at L1-L2

association fibers

connect areas in same cerebral hemisphere

commissural fibers

connect the two cerebral hemispheres - (corpus callosum, anterior commissure)

perception

conscious awareness of a sensation

cerebral peduncles

contain fibers that carry motor output from cerebrum to other regions of CNS

frontal eye field

controls learned eye movements - red

decussation

crossing of the midline that occurs in many tracts so that brain senses and controls contralateral side of body

falx cerebelli

dural fold that separates R/L cerebellum

tentorium cerebelli

dural fold that separates cerebrum from cerebellum

falx cerebri

dural fold that separates the two cerebral hemispheres

folia (brain models)

folds of the surface

cerebellar folia

folds on the surface of the cerebellum, similar to, but thinner than cerebral gyri

phrenic nerve

formed by C3-C5 to the diaphragm (breathing)

somatotopy

functional map of primary somatosensory cortex

cerebrospinal fluid (CSF)

functions 1. supp weight of brain 2. cushion brain/spinal cord from physical trauma 3. transport nutrients, chemical messengers, wastes - produced/maintained by choroid plexus in ventricles - circulates from choroid plexus through ventricles into central canal of spinal cord

nodes of ranvier

gaps in the myelin sheath between internodes

postsynaptic potentials

graded potentials in postsynaptic membrane in response to a neurotransmitter

olfactory foramina

holes in cribriform plate

sensation

information carried by a sensory pathway

somatic reflexes

involuntary control of skeletal muscles (withdrawal reflex)

wernicke's area

language comprehension

projection fibers

link cerebral cortex to diencephalon, brainstem, cerebellum, and spinal cord - all pass through diencephalon

exteroceptors

monitor external environment

visceral sensory neurons

monitor internal conditions and the status of other organ systems

interoceptors

monitor internal organs/systems

proprioceptors

monitor position/mvmt of skele muscs/joints

somatic sensory neurons

monitor the outside world and our position within it

local current

movement of positive charges parallel to the inner and outer surfaces of the membrane (depolarization)

internodes

myelin covered segments from one gap to the next

nerve plexus

network of interweaving anterior rami of spinal nerves

Proprioception

our sense of body position

acquired reflexes (conditioned reflexes)

rapid, automatic learned motor patterns

mechanoreceptors

respond to physical distortion of their plasma membranes 1. proprioceptors (POSITION) 2. baroreceptors (CHANGES IN PRESSURE) 3. tactile receptors (FINE TOUCH) - mechanically gated ion channels

chemoreceptors

respond to water-soluble and lipid-soluble substances dissolved in body fluids

sciatic (sacral plexus) (flat man nerve model)

splits at the knee into tibial and fibular nerves

reflex arc components

stimulus, sensory receptor, sensory neuron, integration center, motor neuron, effector organ

cerebellar cortex

surface covered by thin layer fo gray matter

epineurium

surround entire nerve

perineurium

surrounds groups of axons (fascicles)

endoneurium

surrounds individual axons

thermoreceptors

temperature receptures