A&P Exam 4

Subarachnoid space

Between arachnoid and pia mater. -Filled with CSF.

Somatic Sensory Division

Carries signals from receptors in skin, muscles, bones and joints

Visceral Sensory Division

Carries signals mainly from the viscera of the thoracic and abdominal cavities. For example, heart, lungs, stomach and urinary bladder.

Visceral Motor Division (Autonomic Nervous System ANS)

Carries signals to glands, cardiac muscle and smooth muscle that are usually involuntary.

Somatic Motor Division

Carries signals to skeletal muscles that produces voluntary muscle contractions.

Sensory (afferent) neurons

Carry signals from receptors and transmit the information from stimuli in the PNS to the CNS. The receptors may be a cell or nerve endings of the neuron.

Excitatory neurotransmitters

Cause Depolarization of postsynaptic membranes. -Promote Action Potentials

Inhibitory neurotransmitters

Cause Hyperpolarization of postsynaptic membranes. -Suppress Action Potentials

Upper Motor Neuron

Cell body in CNS -Synapses on lower motor neuron -Can facilitate or inhibit lower motor neuron

Lower Motor Neuron

Cell body in nuclei of brain stem or spinal cord -Triggers contraction

Vestibular Projection Pathways in the Brain.

Cerebellum, Nuclei of Oculomotor trochlear and abducens cranial nerves, Reticular formation, Spinal cord, Thalamus (Cerebral cortex

Parts of the brain

Cerebrum, Cerebellum, Diencephalon- Thalamus Hypothalamus, Epithalamus, Midbrain, Pons, Medulla oblongata

Descending tracts of the spinal cord

- lateral reticulospinal tract - lateral corticospinal tract - rubrospinal tract - medial reticulospinal tract - ventral corticospinal tract - vestibulospinal tract - tectospinal tract

Neuropeptides

Chains of 2-40 amino acids that are stored in secretory granules rather than vesicles. Some function as hormones or neuromodulators

classifications of membrane channels

Chemically Gated Channels- open by chemical binding. Voltage Gated Channels- open by change in membrane potential. Mechanically Gated Channels- open by pressure on channel.

Excitatory Cholinergic Synapse

Cholinergic use Acetylcholine (ACh) and can be excitatory or inhibitory

eyelids

Close for protection and lubricate eyeballs when blinked.

states of gated channels

Closed (but capable of opening) Open/Activated Closed/Inactivated (not capable of opening)

external ear

Collects and directs sound waves.

Ascending, descending , white matter

Columns contain _________ (info up to the brain) and ___________tracts (motor commands to the spinal cord) of ______________.

Anterior cavity

-filled with aqueous humor secreted by the ciliary body. --Anterior chamber- cornea to iris --Posterior chamber- iris to lens.

Spinal tap

A needle is inserted into the subarachnoid space in the inferior lumbar region to remove Cerebrospinal fluid. used to detect abnormalities like infections and can be used in therapeutic procedures.

inhibited.

A neuron becomes ______________ as IPSPs accumulate= Away from threshold so an AP is more difficult to produce. (Less than -70 mV).

facilitated

A neuron becomes ___________as EPSPs accumulate= Close to threshold and an AP can be produced.

Sensory Division (Afferent Division)

carries signals from receptors to inform the CNS of stimuli within and around the body

Motor Division (Efferent Division)

carries signals from the CNS mainly to gland and muscles cells of that carry out the body's responses

Effectors

cause responses that alter conditions in the internal environment

sympathetic responses

Increased metabolic rate, Increased heart rate & blood pressure, Decreased digestive & urinary functions, Activation of sweat glands, Increased respiratory rate & dilation of airways, Heightened mental awareness, Energy reserves activated

step 1 nerve regeneration

Normal nerve fiber.

Purines

Nucleic acids that include adenosine and ATP.

Hyperpolarization

Potential becomes more negative (K+ leave)

eyelashes

Prevent foreign matter from reaching the eyeball

eyebrows

Protect eye from glare & sweat. Enhance facial expression.

Cranial Meninges

Protect the brain and provide a structural framework its arteries and veins. Layers are similar the spinal meninges. Pia Mater Arachnoid Mater Dura Mater- Has 2 layers

Purpose of the Myelination of axons

Protects neurons, Increases the speed of the Action Potential

Orbital fat

Provides padding for the eyeball.

step 1 membrane process

Resting Membrane Potential (RMP)= This is the Potential of undisturbed neuron. Example -70 millivolt millivolt=mv

taste cells

Sense of taste through ______________ located in the tongue and pharynx.

Mechanoreceptors

Sensitive to stimuli that distort the plasma membrane. 3 types Proprioceptors (Position), Baroreceptors (Pressure), Tactile receptors (Touch).

Relative Refractory Period

The membrane can only respond to a stronger stimulus because the membrane is hyperpolarized.

•Absolute Refractory Period

The membrane cannot respond to a stimulus because Na+ channels are inactivated.

Autonomic Efferent Pathways

The neuron (preganglionic) from the synapse synapses with a postganglionic neuron. This neuron reaches the target organ Cell body of preganglionic neuron in the lateral gray horn. Post ganglionic neuron in PNS

step 2 action potential generation

The local potential must reach threshold (change of -70mV to -55mV) to open Na + voltage gated channels.

Peripheral Nervous System (PNS)

all the rest of the nervous tissue found in the human body outside of the brain and spinal cord.

visceral reflexes

automatic motor responses by the ANS that regulate visceral activity and can be modified, facilitated by higher centers

Axoaxonic synapse

axon to axon

Axosomatic synapse

axon to soma

Anterior Root

axons of motor neurons

posterior root

axons of sensory neurons Posterior and Anterior roots join to form a spinal nerve.

Gray Commissures

axons that cross from one side to the other side of the cord before reaching the gray matter.

terminal arborization

branches at the distal end of an axon that ends in an axon terminal

axon collaterals

branches of axon

roots

branches of spinal nerves

Neurofibrils

bundles of actin filaments in soma

Tracts

bundles of axons in the CNS

pupil

lets light in, size is controlled by smooth muscles in the iris.

Spinal blood vessels

located along the pia mater and within the subarachnoid space

rotation

location: Semicircular Ducts receptor area: Crist ampullaris

Gravity and Acceleration

location: Utricle and Saccule receptor area: Maculae

Neurotubules

microtubules in soma

Arachnoid Mater

middle layer of the meninges

white matter

myelinated axons

Saltatory propagation

myelinated neurons, faster as the AP jumps from node of Ranvier to node of Ranvier.

myopia

nearsightedness; lack of foresight

neural tube

origin of the tube. becomes primary and then secondary brain structures.

Subdivisions of the Autonomic Nervous System

parasympathetic, sympathetic

Refractory Periods

periods during an AP that ensure the AP moves in only one direction.

Neuroglia Cells function

protect and support neurons

Adaptation

reduction in sensitivity to a constant and painless stimuli.

Motor (efferent) neurons

send signals from CNS to effectors in the PNS.

PNS divisions

sensory and motor

dural folds

separate major areas of the brain but also stabilize their connection

Falx cerebelli

separates cerebellar hemispheres below the tentorium cerebelli

Tentorium cerebelli

separates cerebrum from cerebellum

sulci

shallow grooves that separate gyri

stereocilia

small hairlike projections on the tops of inner and outer hair cells

Main parts of the neuron

soma (cell body), axons (transmit info), dendrites (receive info)

Subdivisions of motor division

somatic motor division, visceral motor division

Subdivision of Sensory Division of PNS

somatic sensory division, visceral sensory division

Subdural space

space between the arachnoid and dura mater layers of the meninges

Dermatomes

specific bilateral regions of the skin surface. Each spinal nerve except C1 receives information from a dermatome. are clinically important to assess extent of nervous damage

aspartate location and action

spinal cord, affects similar to those of glutamate

creation of local potential

stimulated by opening of chemically gated channels in dendrites and end of axons.

taste buds

structures that contain taste cells. associated with epithelial projections (lingual papillae) on the superior surface of the tongue.

Norepinephrine location and action

sympathetic nervous system, cerebral cortex, hypothalamus, brain stem, cerebellum, and spinal cord, involved in dreaming walking and mood excites cardiac muscles, can excite or inhibit smooth muscle and glands depending on location

visiceral motor divisions of motor divisions

sympathetic, parasympathetic

Axodendritic synapse

synapses between the axon endings of one neuron and the dendrites of other neurons

Inhibitory GABA-ergic Synapse

synapses work the same way as Excitatory Cholinergic Synapses with two significant differences

GABA location and action

thalamus hypothalamus cerebellum, occipital lobes of cerebrum and retina, the most common inhibitory neurotransmitter in the brain

Dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Summation

the collective effects of both EPSPs and IPSPs. -The total will determine if threshold is reached to generate an Action potential.

bony labyrinth of inner ear

tube spaces that are in the bone in our skull; vestibule- inside the window, the neck; semicircular canals on one side of the vestibule, cochlea on the other; lined by membranous labyrinth;

astrocytes, oligodendrocytes, microglia, ependymal

types of neuroglial cells in the CNS

Membrane Potential

unequal distribution of charge (voltage) on the inside vs. the outside of the plasma membrane of a cell.

Classification of Neurons by Structure

unipolar, bipolar, multipolar, anaxonic

gray matter

unmyelinated nerves

Continuous propagation

unmyelinated neurons, slower as it travels along the entire axon.

Excitatory Adrenergic Synapses

use Norepinephrine (NE) and act through 2nd messenger systems like Cyclic AMP (cAMP).

perilymph

very thin fluid between the bone and the membranous labyrinth

Motor Divison of PNS

visceral and somatic

sensory division of PNS

visceral, somatic

synapse

when a signal reaches the end of an axon it reaches a

Presynaptic facilitation

when another neuron enhances the effect of the presynaptic neuron.

Presynaptic inhibition

when another neuron suppresses the effect of the presynaptic neuron.

Anterior White Commissures

where axons cross form right to left.

cochela

where hearing is sensed

Sclera

white fibrous connective tissue that protects and provides attachment point of extrinsic eye muscles.

Anterior median fissure

wide, deep crease along the ventral surface of the spinal cord

Cerebrospinal Fluid Production and Circulation

•CSF flows through the ventricles as well as the rest of the CNS driven by its own pressure and the cilia of ependymal cells. •CSF is produced by the brain (ependymal cells) and reabsorbed into venous circulation. •CSF is produced in the subarachnoid space, general ependymal lining and the choroid plexus.

receptors for hearing

•Each sterocillium has a K+ channel (mechanically gated) at its tip to allow K+ into the cell when vibrated. •When pressure is applied K+ channels open and a depolarization occurs. •In response to depolarization, hair cells release neurotransmitters that bind nerve endings.

propagation

•Generation of an action potential at the axon hillock is moved along the entire axon by ____________Opening of voltage gated channels and the influx of Na+ stimulates the opening of more voltage gated channels downstream.

Crossed Extensor Reflex

•Polysynaptic, Contralateral reflex arc •Additional motor response on the opposite side of the stimuli. •Example- Straightening of leg in response to flexor reflex when stepping on a tack.

Midbrain

•Processes visual and auditory data. •Generates reflexive somatic motor responses. •Maintains consciousness.

sodium potassium pump

•The pump ejects 3 Na+ ions out of the cell for every 2 K + that come into the cell. •This requires energy (ATP) since the ions are pumped against their concentration gradient.

Periosteal Layer

equivalent to periosteum of bone.

neuron physiological properties

excitability, conductivity, secretion

hair cells

mechanoreceptor cells found in the inner ear that transduce stimuli for the senses of hearing and balance

brainstem

medulla oblongata, pons, midbrain

membranous labyrinth

membrane-covered tubes inside the bony labyrinth

three dural folds

falx cerebri, tentorium cerebelli, falx cerebelli

presbyopia

farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

Spinal meninges

fibrous membranes that surround the spinal cord to give the spinal cord stability and provide shock absorption.

tastants

five primary taste sensations or chemical stimuli sweet, salty, sour, bitter, umani

endolymph

fluid within the membranous labyrinth

gyri

folds in the brain

pitch

frequency at which the source of the sound vibrates and is measured by frequency. This is expressed in hertz (Hz).

ascending (sensory) tracts

gracile fasciculus, cuneate fasciculus, spinothalamic, spinoreticular, posterior spinocerebellar, anterior spinocerebellar

histamine location and action

hypothalamus, also potent vasodilator released by mast cells of connective tissue and basophils of the blood

serotonin location and action

hypothalamus, limbic system, cerebellum, retina, and spinal cord, also secreted by blood platelets and intestinal cells, involved in sleepiness alertness thermal regulation and mood

dopamine location and action

hypothalamus, limbic system, cerebral cortex, and retina, highly concentrated in substantia nigra of the midbrain involved in elevation of mood and control of skeletal muscles

enkephalins location and action

hypothalamus, limbic system, pituitary, pain pathways of spinal cord, and nerve endings of digestive tract as analgesics by inhibiting substance P inhibit intestinal mobility, secretion increases sharply and women in labor

epinephrine location and action

hypothalamus, thalamus, spinal cord, and adrenal medulla, affect similar to those of norepinephrine

eyeball cavities

important for the focusing of light and pressure of the eyeball

Meningitis

inflammation of the meninges due to bacterial or viral infection.

glycine location and action

inhibitory neurons of the brain, spinal cord, and retina, most common inhibitory neurotransmitter in the spinal cord

visceral fibers

innervate blood vessels, glands, and viscera

special fibers

innervate more localized organs in the head, including the eyes, ears, olfactory and taste receptors, and muscles of chewing, swallowing, and facial expression

somatic fibers

innervate skin, skeletal muscles, bones, and joints

general fibers

innervate widespread organs such as muscles, skin, glands, viscera, and blood vessels

Neurofilaments

intermediate filaments in soma

descending motor tracts

lateral corticospinal, anterior corticospinal, tectospinal, lateral reticulospinal, medial reticulospinal, lateral vestibulospinal, medial vestibulospinal

Palpebral conjunctiva

Portion that covers the inner surface of eyelid.

changes in membrane potential

Temporary changes in membrane permeability. (Opening and closing of membrane channels due to stimuli)

sympathetic division of ANS

Tends to arouse the body for action. For example to increase heartbeat.

Parasympathetic Division of ANS

Tends to have a calming effect. For example to slow the heartbeat.

Preganglionic neuron synapses on 6-8 ganglionic neurons located

Terminal Ganglion -near target organ 2. Intramural ganglion -embedded in tissues of target organ •The preganglionic fibers leave the brain as cranial nerves (III, VII, IX, X) or leave spinal cord at the sacral level.

Diencephalon

Thalamus- Relays and processes sensory information. Hypothalamus- Controls emotions, autonomic functions, and hormone production.

31

The Spinal cord is divided into ___Segments (bilateral) based on the origin of spinal nerves.

stronger greater

The _____________the stimulus, the ____________ the change in potential and the larger the area affected

Nerve (fibers)

collection of axons in the PNS

Ganglia

collection of cell bodies in the PNS

choroid plexus

combo of ependymal cells and capillaries CSF serves 3 purposes: -Buoyancy -Protection -Chemical Stability

plexus

complex interwoven network of nerves formed from blended fibers of anterior rami of adjacent spinal nerves. They allow multiple spinal nerves to supply the same structures. can contain sensory and motor fibers

water receptors

concentrated in pharynx for water homeostasis

functions of the spinal cord

conduction, neural integration, locomotion, reflexes

Posterior Cavity

contains a gelatinous fluid called the vitreous humor.

medullary cone

cord tapers to a point inferior to lumbar enlargement

axoplasm

cytoplasm of axon

Perikaryon

cytoplasm of soma

RER and ribosomes

(Nissl bodies) make neurotransmitters in soma

Preganglionic neurons

(T1-L2 of spinal cord) synapse with ganglionic neurons located within: -Sympathetic Chain -Collateral ganglia -Adrenal medulla Releases neurotransmitters (NE and E) into blood stream.

Gray matter

(cell bodies of neurons, neuroglia and unmyelinated axons) forms an H shape and surrounds the central canal of the spinal cord.

Ascending tracts of the spinal cord

- Gracile fasciculus - Cuneate fasciculus - Spinothalamic tract - Posterior (dorsal) and anterior (ventral) spinocerebellar tracts

Specialized Areas of the Cerebellum

-Automatic Processing Centers For balance/equilibrium and fine motor movements. -Cerebellar cortex has highly branched Purkinje cells that receive input and relay motor commands. -Arbor vitae-branching array of internal white matter that relays connects the cerebellar cortex to the cerebellar peduncles. -Cerebellar peduncles- collection of tracts that link the cerebellum to other areas of the brain.

Epidural space

-Between dura mater and vertebral canal. -Anesthetic injection site.

Specialized Areas of the Diencephalon

-Pineal gland in Epithalamus -secretes melatonin -Anterior, Ventral, Lateral and Posterior nuclei in Thalamus -Suprachiasmatic nucleus of Hypothalamus- coordinates day/night cycles -Mammilary bodies of Hypothalamus-feeding reflexes

Specialized Areas of the Medulla Oblongata

-autonomic nuclei, includes reticular formation cardiovascular center and respiratory rhythmicity center -Sensory and motor nuclei of cranial nerves -Relay stations along sensory and motor pathways - includes the nucleus gracilis, nucleus cuneatus, solitary nucleus and olivary nuclei

Tunics of the Eyeball

Fibrous layer - sclera and cornea Vascular layer - choroid, ciliary body and iris Internal layer - retina and optic nerve

Steps in Photoreception Active State (In the Light)

1. Light focuses on back of retina. (Pigmented layer) 2. Light is absorbed by retina and photoreceptors. 3.Photoreceptor hyperpolarize.-40mV to -70mV 4.Photoreceptor stop releasing neurotransmitter. 5. Bipolar cells depolarize and release neurotransmitter into synapse with ganglion cells. 6. Ganglion cells depolarize and converge into the optic nerve. Action Potential to CNS!

Photoreception Resting State (Darkness)

1. Photoreceptor cells are at -40mV. (NOT -70mV!!) 2.Photoreceptor cells release neurotransmitter at synapse with bipolar cell. 3. The photoreceptor cell inhibits depolarization of the bipolar cell. NO Signal is stimulated in the optic nerve.

Main Membrane Processes

1. Resting Membrane Potential (RMP)= This is the Potential of undisturbed neuron. Example -70 millivolt millivolt=mv 2. Local (Graded) Potential= A Temporary, local change in membrane potential. 3. Action Potential= Change in potential that spreads along the axon to the axon terminal. Initiated by a Local Potential. 4. Synaptic Transmission= Release and binding of neurotransmitters creates a Local Potential on postsynaptic membrane. 5. Information Processing= Response by the postsynaptic cell.

4 types of papillae

Filiform, Foliate, Fungiform and Vallate Papillae.

Visual pathway (sensory)

1.1st order neuron is the bipolar neuron. 2.2nd order neuron is the retinal ganglion cell whose axons are the fibers of the optic nerve. 3.Optic nerve fibers converge at the optic chiasm and decuss before they reach the thalamus. 4.The 3rd order neuron at the thalamus takes the information to the primary visual cortex.

Brain structures that are or may be involved in memory consolidation

1.Amygdaloid body (limbic system) 2.Hippocampus (limbic system) 3.Tracts from amygdaloid body to hypothalamus- may link memories to specific emotions. 4.Tracts from hippocampus, amygdaloid body, cerebral cortex areas to nucleus basalis- may play role in memory storage and retrieval.

Five Steps of a Reflex Arc

1.Arrival of a Stimulus, activation of a receptor 2.Activation of a sensory neuron (By local depolarization) 3.Information processing in the CNS. 4.Activation of a motor neuron (Action potential) 5.Response by a peripheral effector

Steps at an Excitatory Cholinergic Synapse

1.Arrival of signal at axon terminal opens Ca2+ gated channels. 2.Ca2+ enters and triggers exocytosis of synaptic vesicles which releases ACh. 3.Empty vesicles refill with ACh in axoplasm. 4.ACh binds ACh receptors which are Na+ channels. 5.Depolarization of the membrane occurs. It is a Local potential and if large enough stimulates an Action potential.

Cessation of the Signal steps

1.Breakdown the neurotransmitter by an enzyme in the synaptic cleft. 2.The neurotransmitter or its parts are transported back into the presynaptic cell. 3.Or the neurotransmitter diffuses away.

The Cerebrum Specialized Areas

1.Cerebral Cortex- gray matter divided into hemispheres and lobes. Frontal, Parietal, Temporal, Occipital, Insula 2.Basal nuclei-gray matter deep to lateral ventricle -Control of subconscious activities. 3. White matter- found deep to the cerebral cortex -tracts of fibers interconnecting the brain.

Effects of aging result in

1.Decrease in memory consolidation. 2.Decrease in hearing, balance, vision, smell and taste. 3.Decrease in reaction rates. 4.Decrease in precise motor control

Accessory Structures of the Eye

1.Eyebrows 2.Eyelashes 3.Eyelids 4.Lacrimal caruncle 5.Tarsal Glands 6.Conjunctiva 7.Orbital Fat 8.Lacrimal Apparatus 9.Eye Muscles

Inhibitory GABA-ergic synapses steps

1.GABA is used as the neurotransmitter. 2.GABA binds the GABA receptor on the post synaptic membrane. The GABA receptor is a chloride ion channel and when opened Cl- enters the cell making it more negative (hyperpolarization).

auditory pathway

1.Hair cells release neurotransmitter into synapses with cochlear nerve fibers. These fibers become the cochlear nerve and join the vestibular branch. 2.Auditory information is taken to cochlear nuclei in the medulla oblongata and synapse with secondary neurons that take the signal to the pons. There the info is relayed back to the inner ear for tuning, processed and relayed to the midbrain. 3.At the midbrain the info is processed and through a third order neuron sent to the thalamus. 4.At the thalamus a fourth order neuron sends the signal to the primary auditory cortex.

Autonomic Nervous System Organization

1.Integrative Centers (hypothalamus) 2.Visceral Motor Neurons called preganglionic neurons. - Cell bodies are located in the Central Nervous System and synapses with the postganglionic neurons. 3. Visceral Motor Neurons called postganglionic neurons. -Cell bodies in autonomic ganglia, synapses with preganglionic neuron and innervates visceral effectors. 4. Visceral Effectors- Targets that are stimulated by a diffuse release of neurotransmitter into the tissue possibly affecting many cells simultaneously.

pathway of tears

1.Lacrimal punctum 2.Lacrimal canaliculus 3.Lacrimal sac 4.Nasolacrimal duct

Steps to Generate an Action Potential (AP)

1.Local current generated by a local potential arrives at the axon hillock of the axon. 2.The local potential must reach threshold (change of -70mV to -55mV) to open Na + voltage gated channels. 3.Na+ enters the cell changing the membrane potential to 0 mV. 4.Na+ gated channels are inactivated at 0 mV and by the time inflow stops the membrane potential is +35 mV. Positive membrane potential. 5.By this time K+ voltage gated channels open with the positive membrane potential and K+ leaves the cell to repolarize the membrane. 6.More K+ leaves the cell than is needed to reach -70 mV so the membrane potential is more negative= Hyperpolarization. 7.RMP is restored through leaky channels and the Na + / K + pump.

Equilibrium Pathway

1.Movement of the stereocilia and a kinocilum on the hair cell results in depolarization of the hair cell and its release of neurotransmitter into its synaptic cleft with a fiber of the vestibular nerve (branch of CNVIII). 2.The signal from vestibular nerve fibers is taken to four vestibular nuclei on each SIDE of the pons and medulla oblongata. 3.These four nuclei process the information and relay it to five additional targets shown in figure 16.22 for further integration. Cerebellum (1st order , 2nd order), Nuclei of oculomotor, trochlear, abducens nerves (midbrain), reticular formation (pons_, spinal cord and thalamus (to cerebral cortex).

Excitatory Adrenergic Synapses steps

1.NE receptor is bound to a G protein. 2.NE binds receptor and G protein leaves receptor. 3.G protein bind adenylate cyclase which converts ATP to cAMP. cAMP has several possible effects. Open ion channels from inside the cell and cause depolarization at membrane. Activate enzymes to cause metabolic changes in the cell. Gene transcription of new enzymes to cause metabolic changes in cell.

steps of Nerve Regeneration After Injury

1.Normal nerve fiber. 2.Injury- Macrophages clean up site at point of injury and area distal to break. 3.Degeneration of severed fiber.- Proximal stump of injury sprouts growth processes while the distal end shrinks. 4.Early regeneration- Schwann cells help form a regeneration tube, one growth process finds its way to this tube. 5.Late regeneration-The regeneration tube connects to the distal stump. 6.Regenerated fiber- With contact reinnervated nerve fiber grow.

Olfaction pathway

1.Odorant binds receptor which activates a 2nd messenger system to cause depolarization. 2.Depolarization triggers an action potential and the signal is transmitted to the primary olfactory cortex (and insula, orbitofrontal cortex.)

Parts of the Sensory Pathway (Afferent Division)

1.Receptors Specialized cells that monitor conditions internally or externally. 2. Sensory Neurons Part of the sensory pathway to connect the receptor stimuli to the Central Nervous system. 3. Sensory Pathways Deliver Sensory information to the Central Nervous System using nerves, nuclei and tracts.

Visceral Reflex Arc

1.Receptors- Nerve endings. 2.Afferent neurons-Take sensory information to the CNS. 3.Integrating Center-Signal is taken to interneurons in autonomic centers in CNS. 4.Efferent neuron- Carry motor signals away from the CNS. 5.Effector-Carries out the end response.

hearing pathway

1.Sound waves are collected by the external ear and arrive at the tympanic membrane. 2.Movement of the tympanic membrane displaces the auditory ossicles. 3.Movement of the stapes at the oval window produces pressure waves in the perilymph of the cochlea of the inner ear in the scala vestibuli. 4.On the way to the scala tympani the pressure waves distort the basilar membrane in the spiral organ. 5.Distortion of the basilar membrane causes vibration of the hair cells against the tectorial membrane which depolarizes the hair cells. 6.The hair cells release neurotransmitter which stimulates the cochlear nerve. This information is relayed to the CNS.

General Senses

1.Temperature 2.Pain 3.Touch 4.Pressure 5.Vibration 6.Proprioception

The Gustatory Pathway

1.The tastant stimulates the taste cell that synapses with a sensory neuron. 2.Stimulation of the taste cell causes its depolarization and release of neurotransmitters into its synapse with the first order neuron. 3.The neurotransmitters bind receptors on the dendrites of the cranial nerves (V, IX, X) to result in a local depolarization and then an action potential that takes the signal (info) to the medulla oblongata. 4.Second order neurons then relay the information to: a. the hypothalamus and amygdala b. the thalamus 5.A third order neuron at the thalamus relays the signal to the primary gustatory cortex. This info is integrated at orbitofrontal cortex with info from nose and eyes.

neurons in a sensory pathway

1st order neuron- A sensory neuron 2nd order neuron- An interneuron in CNS that synapses with the 1st. 3rd order neuron- Synapses with the 2nd in the thalamus

Segments of Spinal cord

8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccyx

Enteric Nervous System (ENS)

A 3rd division of the Autonomic Nervous System (ANS) An extensive network in digestive tract walls. Coordinates complex visceral reflexes locally.

Cerebral Aqueduct

A canal that connects the third and fourth ventricles.

hyperopia

A condition in which visual images come to a focus behind the retina of the eye and vision is better for distant than for near objects -- called also farsightedness.

Conjunctiva

A layer of tissue that covers the surfaces of the inner eyelids and anterior eyeball.

tectorial membrane

A membrane located above the basilar membrane; serves as a shelf against which the cilia of the auditory hair cells move

inhibited

A more negative potential is less likely to produces an action potential because the membrane is further away from threshold (-55mV) and thus ___________

classes of neurotransmitters

Acetylcholine, Amino Acid, Monoamines (biogenic amines), Purines, Gases, Neuropeptides

step 3 membrane process

Action Potential= Change in potential that spreads along the axon to the axon terminal. Initiated by a Local Potential.

propagate

Action Potentials (AP) once generated, ___________changes in membrane potential along the axon.

middle ear

Air filled chamber that amplifies sound waves. (Tympanic membrane and auditory ossicles (Malleus, Incus, Stapes) -Auditory tube that goes to the nasopharynx to aid in pressure regulation.

excitability of neurons

All cells respond to environmental changes known as stimuli.

Passive Channels (Leak Channels)

Always open. Permeability can change with condition.

Memories may be made by developing a circuit (memory engram) by:

An increase in the amount of neurotransmitter released at a synapse. Facilitation at a synapse- Synapse is closer to threshold. Making additional synaptic connections between neurons

Ciliary body

Anterior extension of choroid that forms a muscular ring around lens.

cornea

Anterior portion that is clear to let light in.

look at the diagram

Ascending and Descending Tracts in the Spinal Column

touch

At a chemical synapse the cells do not _________ and transmission of the signal is by neurotransmitter.

neurotransmitters

At the synapse, the signal triggers the release of __________ that stimulates a local potential in the next cell

axon structure

Axon Hillock, Axoplasm, Axolemma, Axon Collaterals, Terminal arborization, Axon terminals

Fourth Ventricle

Becomes the central canal of the spinal cord

Cessation of the Signal

Binding of the neurotransmitter to its receptor on the post synaptic membrane is quick (1ms) and then it leaves to be replaced by another neurotransmitter.

Blood Brain Barrier

Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out lets water, glucose and lipid substances through easily and slightly permeable to ions like sodium and potassium as wells as waste products leaving.

Central Nervous System (CNS)

Brain and Spinal that are enclosed in the Dorsal Cavity

Electroencephalogram

Brain waves indicate electrical activity, An electroencephalogram (EEG) is a record of this activity.

step 5 action potential generation

By this time K+ voltage gated channels open with the positive membrane potential and K+ leaves the cell to repolarize the membrane.

2 entries of blood brain barrier

Capillaries throughout brain tissue and the capillaries of the choroid plexus.

Axon Hillock

Cone shaped region of an axon where it joins the cell body.

Cerebrum

Conscious thought processes, intellectual functions. Memory storage and processing. Conscious and subconscious regulation of skeletal muscle contractions.

Posterior Gray Horns

Contain sensory nuclei (incoming info from receptors)

Anterior Gray Horns

Contain somatic motor nuclei (Outgoing info to effectors)

Lateral Gray Horns

Contain visceral motor nuclei (Outgoing info to effectors)

inner ear

Contains sensory organs for hearing and equilibrium. - Divided into the bony and membranous labyrinth separated by fluid called perilymph.

Cerebellum

Coordinates complex somatic motor patterns. Adjusts output of other somatic motor centers in brain and spinal cord.

Brain Support and Protected

Cranial Bones of the Skull Cranial Meninges Ventricles and Cerebrospinal fluid (CSF) Blood-brain barrier

Aging and the Nervous System

Decline in the nervous system begins by age 30 and is noticeable by age 65. This includes: -Reduction in brain size and weight. -Reduction in # of neurons. -Decrease in blood flow to brain due to arteriosclerosis (fat build up). -Changes in synaptic organization of the brain. -Intra and extra cellular changes in CNS neurons. Ex. Accumulation of lipofuscin, neurofibrillary tangles and plaques (mat of fibrillar proteins that appear in the hippocampus).

Parasympathetic responses

Decreased metabolic rate, Decreased heart rate & blood pressure, Stimulation of urination & defecation, Increased secretion by the salivary and digestive glands, Increased mobility and blood flow to digestive tract REST AND DIGEST

landmarks of the cerebral cortex

Deep Longitudinal Fissure, Central Sulcus, Lateral Sulcus, Parieto-occipital Sulcus, Cingulate Gyrus, Precentral and Postcentral Gyrus

fissures

Deep grooves that subdivide the hemisphere.

step 3 nerve regeneration

Degeneration of severed fiber., Proximal stump of injury sprouts growth processes while the distal end shrinks.

Epineurium

Dense outer network of collagen fibers.

step 4 nerve regeneration

Early regeneration, Schwann cells help form a regeneration tube, one growth process finds its way to this tube.

features of autonomic nervous system

Efferent Division. -no conscious instruction -visceral effectors -coordinates system functions. (like respiration, digestion)

Interneurons

Entirely within the CNS and receive information from sensory neurons. They process the information, determine the response and then send instructions to the appropriate Motor (efferent) neuron.

lens

Focuses light from visual image to photoreceptors in retina, held in place by ciliary body.

Astrocytes

Form supportive framework for the nervous tissue. Form the blood-brain barrier. Monitor neuron activity. Provide nourishment for neurons. Regulate nerve development. Influence communication between neurons. Regulate composition of nervous tissue fluid. Form scar tissue in CNS

Acetylcholine

Formed from acetic acid and choline.

denticulate ligaments

From pia to dura mater are paired ________________ that stabilize side to side movement by anchoring the pia mater to the dura mater.

Amino Acids

Glycine, glutamate, aspartate and gamma-aminobutyric acid (GABA) are amino acids that are neurotransmitters.

local potential characteristics

Graded- Vary according to the strength of stimulus. Local potentials get weaker as they spread from the point of origin. They are reversible if stimulation ceases. Can be excitatory (depolarization) or inhibitory (hyperpolarization.

Choroid

Highly vascularized located behind retina.

Parasympathetic Division

In control during resting conditions Preganglionic Fibers: long Postganglionic Fibers: short Synapse Location: In ganglia close to or within target organ.

step 5 membrane process

Information Processing= Response by the postsynaptic cell.

step 2 nerve regeneration

Injury, Macrophages clean up site at point of injury and area distal to break.

Endoneurium

Innermost layer that surrounds individual neurons.

pia mater

Innermost, delicate mesh-like layer that is firmly bound to neural tissue.

converging circuit

Input from many neurons is funneled to fewer.

parallel after discharge circuit

Input neuron diverges and stimulates several chains. Signal reconverges on output neuron from each chain at different times. Continued firing after the stimulus stops is referred to as after-discharge. Example- Seeing the image of a lamp after closing eyes.

The Sympathetic Division

Kicks in during exertion, stress or emergency. Preganglionic Fibers: short Postganglionic Fibers: long Synapse Location: In ganglia near spinal cord

Long term

Last much longer. Secondary memory- Fades with time and requires effort to recall. Tertiary memory-Present for a lifetime and easy to recall.

step 5 nerve regeneration

Late regeneration, The regeneration tube connects to the distal stump.

step 3 action potential generation

Na+ enters the cell changing the membrane potential to 0 mV.

step 4 action potential generation

Na+ gated channels are inactivated at 0 mV and by the time inflow stops the membrane potential is +35 mV. Positive membrane potential

Skill Memories

Learned motor behaviors. Innate (brainstem) Complex (basal nuclei, cerebral cortex and cerebellum)

Ependymal Cells

Lines the dorsal cavity, produces and circulates Cerebrospinal fluid (CNS).

step 2 membrane process

Local (Graded) Potential= A Temporary, local change in membrane potential.

step 1 action potential generation

Local current generated by a local potential arrives at the axon hillock of the axon.

Lacrimal caruncle

Located at a medial angle, produces a thick secretion to trap deposits.

Axon

Long structure that carries a signal (action potential) to target

Monoamines

Made from amino acids by removal of the carboxy group.

resting membrane potential

Na+ ions are more concentrated outside the cell but diffuse into the cell by leaky channels in the membrane. K+ ions are more concentrated inside the cell but diffuse out of the cell by leaky channels in the membrane. The RMP is stabilized by the active force of the sodium-potassium exchange pump.

electrochemical gradients

Membrane potentials are established by ____________

Perineurium

Middle layer that separates nerve into fascicles (axon bundles)

Tarsal Glands

Modified sebaceous glands that prevent eyelids sticking by secretion of product.

Neurotransmitters

Molecules made by a neuron, released when a signal reaches the end of the neuron and have an effect on receiving cells physiology.

Stretch Reflex

Monosynaptic- uses one synapse. Regulation of skeletal muscle cell length. Example- The Patellar Reflex aka Knee jerk Example- Postural Reflex- helps maintain upright position

step 6 action potential generation

More K+ leaves the cell than is needed to reach -70 mV so the membrane potential is more negative= Hyperpolarization.

Somatic Nervous System in the Efferent Division

Motor neurons and pathways that control skeletal muscles. -Nuclei (collection of cell bodies in CNS) -Motor tracts (collection of efferent axons in CNS) -Motor neurons

Anaxonic neuron

Multiple dendrites but no axon. Found in the brain as interneurons and in the eye and adrenal medulla.

internodes, nodes of Ranvier.

Myelin sheaths form around segments of the axon called ____________with spaces in between called ____________.

do not

Neurons ________divide and if a cell body is damaged the neuron is lost, if only the nerve is damaged it repairs

electrical signals

Neurons are able to communicate using ____________

Reverberating

Neurons are stimulated in a linear sequence but some of the neurons may send branches back to stimulate neurons earlier in the pathway.

neural pools, neural circuits

Neurons function in larger groups called _______________ that form different pathways of neurons called _____________. These are extensive in the brain.

Conductivity of neurons

Neurons respond to stimuli by producing electric signals that are quickly transferred to other cells at different locations.

postsynaptic potentials

Neurotransmitter messages are received by many dendrites on a neuron at the same time. These are Local (Graded) Potentials that are called ______________

Gases

Nitric Oxide (NO) and carbon monoxide (CO) are synthesized as needed rather than stored in synaptic vesicles.

special senses

Olfaction- Smell Gustation- Taste Vision Equilibrium Hearing

Multipolar neurons

One axon and multiple dendrites. Most common type

Bipolar neurons

One axon and one dendrite. Rare but most notably found in the nose, eye and ear.

Unipolar neurons

One long axon that at one end branches into many dendrites. Sensory neurons are unipolar, stimuli is received by the dendrites and taken to the CNS by the axon.

somatic pathway

One neuron from CNS reaches target organ. Cell body of motor neuron in th anterior gray horn

diverging circuit

One neuron sends signals to many.

Active Channels (Gated Channels)

Open and Close in Response to Stimuli. Closed at resting potential.

Dura Mater

Outermost, tough, fibrous

loudness

Perception of sound energy, intensity or amplitude of vibration. This is expressed in decibels (dB).

parts of the soma

Perikaryon, Neurofilaments, Neurotubules, Neurofibrils, Mitochondria, RER and ribosomes, Large nucleus and nucleolus

Microglia cells

Phagocytize and destroy microorganisms , foreign matter and dead nervous tissue- immune function.

neurons of the retina

Photoreceptors, Bipolar Cells, Ganglion Cells

iris

Pigmented structure that controls the diameter of the pupil.

Flexor (Withdrawal) Reflex

Polysynaptic Movement of body part away from stimulus. Response strength depends on intensity and location of stimulus Example- Moving hand away from a hot stove.

Ocular conjunctiva

Portion that covers the anterior eyeball.

step 7 action potential generation

RMP is restored through leaky channels and the Na + / K + pump.

Temporal Summation

Rapid, repeated stimuli at 1 synapse.

vestibular branch

Receptor cells transmit sound to the ___________ _______of the Vestibulocochlear Nerve (Cranial Nerve VIII).

Chemoreceptors

Receptors for soluble substances dissolve in body fluid. Example- Glucose

Thermoreceptors

Receptors that sense a change in temperature.

Nociceptors

Receptors that sense painful stimuli

step 6 nerve regeneration

Regenerated fiber, With contact reinnervated nerve fiber grow.

Lateral & Medial Commissures

Region where upper and lower eyelids meet.

Tendon Reflex

Regulates the length of skeletal muscle. Receptors are activated in response to excessive tension to ensure the tendon's attachment to bone or muscle. Stimulates an inhibitory response. Polysynaptic.

Pons

Relays sensory information to cerebellum and thalamus. Contains subconscious somatic and visceral motor centers.

Medulla Oblongata

Relays sensory information to thalamus and to other portions of the brain stem. Contains autonomic centers for regulation of visceral function: Cardiovascular, Respiratory, and Digestive System Activities.

reflexes

Require stimulation. Take place quickly. Involuntary Stereotyped- Occur in the same way each time.

higher order functions

Require the cerebral cortex to function. Involve conscious and unconscious information processing Subject to adjustment over time. They are not innate. Focus on Memory * Other Examples: Sleep, Cognition, emotion, sensation, motor control, language.

Specialized Area of the Pons

Sensory and Motor Nuclei of Cranial Nerves. Reticular formation that contains 2 respiratory centers. Nuclei and tracts to relay info from and to the cerebellum. Ascending, descending and transverse tracts.

Cervical Plexus (C1-C5)

Sensory input from skin of head/neck/shoulder Motor output to neck muscles Phrenic nerve supplies diaphragm

Brachial Plexus (C5-T1)

Sensory input from skin of upper limbs Motor output to muscles of upper limbs

Lumbar Plexus (L1-L4)

Sensory input from skin over the inferior abdomen, buttocks, genitalia and lower limbs. Motor output to muscles of the lower limbs, outer genitalia and abdominal wall.

Sacral Plexus (L4-S4)

Sensory input lower limb and genitalia. Motor output to muscles of the buttocks and lower limbs like the sciatic nerve

Lateral Ventricles

Separated by the septum pellucidum.

presynaptic cell, postsynaptic cell

Signals arrive at the synapse via the ________________ and the _________________ responds to the neurotransmitter release.

Spatial Summation

Simultaneous stimuli at multiple synapses.

Short term

Small bits of information that do not last long but can be recalled easily.

reflex arc

Somatic Reflexes are reflexes of skeletal muscles and the overall process of a reflex is called a

Fact Memories

Specific bits of information.

Specialized Areas of the Midbrain

Tectum (roof) - contain sensory nuclei Superior colliculus (visual) Inferior colliculus (auditory) Tegmentum (walls and floor) Red nucleus -Substantia nigra -Reticular formation Cerebral peduncles

Satellite cells

Surround cell bodies in ganglia. Provide insulation to cell bodies and regulate the chemical environment of those neurons

Divisions of the Autonomic Nervous System

Sympathetic Division Parasympathetic Division Enteric Nervous System

step 4 membrane process

Synaptic Transmission= Release and binding of neurotransmitters creates a Local Potential on postsynaptic membrane.

refraction

The bending of a wave as it passes at an angle from one medium to another

an anterior root

The cell bodies of ____________ _______________ ______________ are located within the spinal cord and these carry motor information to effectors.

Palpebral fissure

The gap between upper and lower eyelids.

Third Ventricle

The interventricular foramen connects the third ventricle to the lateral ventricles.

Lacrimal apparatus

The lacrimal gland produces tears that contain antibiotics. Tears drain to nasal cavity.

normal membrane potential

The permeability for Na+ ions is low. The permeability for K+ ions is high.

vestibule

The portion of the inner ear that senses the position of the head. Its sensory epithelium is contained in two saclike spaces: the utricle and the saccule.

Information processing

the response of the postsynaptic cell.

Synaptic Fatigue

The synapse eventually becomes inactive because the neurotransmitters are not recycled fast enough.

limbic system

These are nuclei and tracts found between the cerebrum and diencephalon Functional grouping that -Establishes emotional states. -Links function from cerebrum to brain stem. -Facilitates memory storage and retrieval

Extrinsic Eye Muscles

These attach to the surface of the eye and do not control the lens shape or pupil. There are six in total Superior, Inferior, medial and lateral rectus Superior and inferior oblique

kinocilium

This is a large hair cell important in the detection of the head's position. Whether the displacement of the stereocilia is towards or away from this determines whether it is excitatory or inhibitory.

synaptic delay

Transmission at a synapse takes about 0.5 ms which is referred to as a

Schwann cells, Satellite cells

Types of neuroglia cells in the PNS

ACh

Used for release of ______at motor end plates, trigger cellular function like glandular secretion and to stimulate an action potential.

dual innervation

When both Parasympathetic and Sympathetic Divisions reach the same targets. Example: dilation and constriction of pupil

secretion of neurons

When the signal the neuron carries reaches the end of the neuron in most cases it releases a neurotransmitter that stimulates the next cell.

Posterior, Lateral and Anterior Columns

White matter in the spinal cord is superficial to Gray Matter and organized into ____________

cauda equine

a bundle of nerve roots that occupies the vertebral canal below L2, looks like a horse's tail, hence the name

astigmatism

a condition in which the eye does not focus properly because of uneven curvatures of the cornea

Meningeal Layer

a layer continuous with the spinal cord layer and has in places within into the cranial cavity called dural folds

Posterior median sulcus

a shallow vertical groove dividing the spinal cord throughout its whole length in the midline posteriorly.

neuron

a specialized cell transmitting nerve impulses; a nerve cell.

basilar membrane

a structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid

Fovea centralis of the macula

area in the back of the retina with the highest concentration of photoreceptors

substance p location and action

basal nuclei, midbrain, hypothalamus, cerebral cortex, small intestine, and pain receptor neurons, mediates pain transmission

classes of neurons

based upon the movement of the signal in the nervous system. sensory (afferent), motor (efferent), interneurons

falx cerebri

between cerebral hemispheres

2nd largest part of the brain

cerebellum

Gluamate location and action

cerebral cortex and brainstem accounts for about 75% of all excitatory synaptic transmission in the brain, involved in learning and memory

cholecystokinin location and action

cerebral cortex and small intestine. suppressed appetite

largest part of the adult brain

cerebrum

types of plexuses

cervical, brachial, lumbar, sacral

Ventricles

chambers formed during development that are filled with Cerebrospinal fluid (CSF) and are lined with ependymal cells. CSF is a clear fluid fills the ventricles and circulates throughout the dorsal cavity

posterior root ganglion

cluster of cell bodies for sensory neurons

nuclei

clusters of cell bodies in the CNS

B-endorphin location and action

digestive tract, spinal cord, and many parts of the brain, all secreted by a hormone in the pituitary, suppresses pain reduces perception of fatigue and may produce runners high in athletes

odorants

dissolved chemicals that stimulate olfactory receptors

Types of neural circuits

diverging, converging, reverberating, parallel after discharge

grooves

divide the spinal cord into left and right

axon terminal

ends of the axon that form part of the synapse.

mixed nerves

nerves carrying both sensory and motor fibers

efferent fibers

nerves composed of only motor axons from cns to effectors

afferent fibers

nerves composed of only sensory axons carry sensory signals from receptors to the cns

acetylcholine location and action

neuromuscular junctions most synopsis of auto gnomic nervous system, retina, and many parts of the brain, excite skeletal muscle, inhibits cardiac muscle, and has excitatory or inhibitory effects on smooth muscle and glands depending on location

Hearing and Equilibrium

occur in the inner ear which is a maze of fluid filled passages with receptor cells that are stimulated by sound waves.

dural sinus

places where the 2 layers are separated. contain collecting veins.

Axolemma

plasma membrane of axon

Depolarization

positive change in potential (Na+ enter)

optic nerve

posterior to the eyeball, leaves the retina at the blind spot.

Memory Consolidation

process of storing memories.

brain stem

processes information between the spinal cord and the cerebrum or cerebellum

Oligodendrocytes

produce myelin in CNS

Schwann cells

produce myelin in PNS assist in regeneration of nerve fibers.

local potential

produced by gated channels on the dendrites and soma may be positive (depolarizing) or negative (hyperpolarizing) voltage change. Graded proportional to stimulus strength. Reversible returned to RPM if stimulation ceases before threshold is reached. Local has effects for only a short distance from point of origin. decremental: signal grows weaker with distance

action potential

produced by voltage gated channels on the triggers zone and axon always begins with depolarization either does not occur at all or exhibits the same peak voltage regardless of stimulus strength irreversible, goes to completion once it begins self propagating has effects of a great distance from the point of origin signal maintains same strength regardless of distance

Olfactory receptors

the dendrites of specialized neurons embedded in the olfactory mucosa.

retina

the innermost layers that contains photoreceptor cells and the beginning of the optic nerve

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina

diencephalon

the structural and functional link between the cerebrum and the rest of the brain.

Oleogustus

the taste of fat

Optical Components

transparent elements that are responsible for focusing images on the retina cornea, aqueous humor, lens and vitreous humor

neuromodulators

•chemicals released at axon terminals that may alter rate of release of neurotransmitter or response by the postsynaptic cell. •Can have a longer term effect than a neurotransmitter on a neuron or groups of neurons. •They can be released from the presynaptic membrane alone or with a neurotransmitter. Some are considered neurotransmitters. •Example- Nitric Oxide (NO)- Relaxes smooth muscle.