• touch 
• pressure
• pain
• tempurature
• itch

• smell
• taste
• sight
• hearing
• balance

general sense

somatic

• provides info about body and environment

general sense

visceral

• provides information about interrnal organs, pain pressure

Respond to painful stimuli, temp, itch, or movement 

in epidermis

Detect light tough and superficial pressure

in epidermis and dermis

Detects light touch 

in dermis 

Involved in fine, descrimive touch 

in dermis 

Detects continuous touch or pressure

( holding hands )

in dermis

Detects deep pressure, vibration, and position

in deep dermis

• Deep tissue neurons coverage with ascending neurons of superficial areas 
• Brain can't distinguish signals 

How does olfaction work? 

Process

• Odorants dissolve in mucus 
• Cilia on dendrites of olfactory neurons pick up on odor
• Depolarize 
• AP to axon in olfactory bulb (cranial nerve 1) 
• Synapse with interneurons 
• Olfactory cortex

1. Taste hairs of taste cells
2. Sensory neurons 
3. Cerebral cortex

Neurons: facial (7), glossopharyngeal (9), vagus (10)

• Sweet
• Sour
• Salty 
• Bitter
• Umami 

Help move eyeball

4 rectus (long) and 2 oblique (around)

Produces tears

gland at top of eye

1. Retina nervous tunic... deep
2. choroid vascular tunic ... mid
3. sclera fibrous tunic ...superficial

filled with vitreous humor (jelly like substance)

behind the lens

helps maintain pressure, holds lens and retinal in place, refracts light

filled with aqueous humor (water like)

separated by the iris

between cornea and lens

helps maintain pressure, refracts light, and provides nutrients to inner surface of eye

produced by the ciliary body, reabsorbed by venous ring in cornea and blockage causes glaucoma

firm white outer part of eye

helps maintain eye shape, provides attachment sites, protects internal structures

fibrous tunic (superficial)

transparent structure that covers iris and pupil

allows light to enter and focuses light

fibrous tunic (superficial)

black part (melanin) prevents reflection

delievers O2 and nutrients to retina

vascular tunic (mid)

helps hold lens in place via ciliary muscles and suspensory ligaments

vascular tunic (mid)

colored part

surrounds and regulates pupil

vascular tunic (mid)

functional in low light and are part of the sympathetic system

dilate the pupil

functional in hight light

constrict the pupil

pigmented: outer layer; prevents light from reflecting back into the eye

sensory: contains photoreceptors (rods and cones) and interneurons

nervous tunic (deep)

photoreceptor sensitive to light

can function in dim light

no color vision

photoreceptor provide color vision

3 types: blue, green, red

needs lots of light

composed of opsin (colorless protein)  and retinal (requires vit A and is yellow pigment)

works in the disc of a photoreceptor

1. retinal attaches inside opsin making rhodopsin
2. light activates rhodopsin by causing retinal to change shape, opsin thus changes shape
3. activated rhodopsin stimulates cell changes that result in vision
4. following rhodopsin activation, retinal detaches from opsin
5. energy from ATP is required to bring retinal back to its original form
6. retinal attaches to opsin to from rhodopsin

1. light
2. rods and cones
3. bipolar cells and horizontal cells of sensory retina (these are interneurons)
4. ganglion cells
5. Ganglion cell's axons coverge to form optic nerve
6. connect outside cranial cavity to optic chasm

blood vessels enter eye and spread over retinal

axons exit as optic nerve

no photoreceptors so called blind spot

• cilliary muscles in the cillary body are relaxed
• tension in suspensory ligaments is high
• Lens flattened

• cilliary muscles in the cillary body contract, moving cilliary body toward lens
• tension in suspensory ligaments is low
• Lens thickened

nerves to face

ganglia

nerves to upper limb

nerves to lower limb

unconscious control

transmits action potential from the CNS to

cardiac muscles

smooth muscles (digestion)

glands

 goes through an autonomic ganglion outside the CNS

divides pre and post ganglionic nerves

 exception: preganglionic neuron that extends to the adreanal gland...postganglionic neurons are the hormone secreting glands in this case

two parts sympathetic and parasympathetic divisions

they recieve signals in the dendrites and conduct AP through thier axons

sensory neurons to CNS to motor neurons

transmit signals

motor neurons

multiple dendrites

nasal cavity 

one dendrite

sensory neurons

no dendrites

nonneuronal cells of the CNS and PNS

more numerous than neurons

retain the ability to divide (neurons can't)

5 types: astrocyte, ependymal cells, microglia cells, oligodendrocyte, and schwann cells

highly branched

provieds support

regulates neuronal signaling

contriute to blood-brain barrier

help with neural repair

epithelial-like

line ventricles of brain and central canal of the spinal cord

circulate cerebrospinal fluid (cilia)

some form choroid plexuses

which produce CSF

small, mobile cells

protect CNS from infection (immune cells of CNS)

become phagocytic in response to inflammation

cells with processes that can souround several axons

cell processes form myelin sheaths around axons or enclose unmyelinated axons in the CNS

single cells surrounding axons

form myelin sheaths around axons or enclose unmyelinated axons in the PNS

gaps in the myelin sheaths that occur about every millimeter between oligodendryocyte segments or between individual schwann cells

allows ion movement across

increases the speed and efficienty of an action potential generated along the axon

prevents ion movement which then must only occure at the nodes of Ranvier

groups of neuron cell bodies and their dendrites, very little myelin

Cerebral cortex: grey matter on the ouside

Spinal cord: grey matter on the inside shaped like an H and has horns (anterior, posterior and lateral)

bundles of parallel axons with myelin sheaths (white color) forms nerve tracts which propagate action potentials from one area of the CNS to another

cerebral cortex: inside cortex on neurons

brainstem: outside cortex on neurons

inside is negative compared to the outside creating polarized membrane.

higher concentration of K+ immediately inside the cell membrane

higher concentration of Na+ immediatlely outside the cell membrane

greater permeability of cell membrane to K+ than to Na+

permeability depends on number of open ion channels

are alway open... ions leak down thier concentration gradient

many more K leak channels so K have a greater contribution to the resting membrane potential

closed until opened by specific signals

chemically gated (neurotransmiters or other chemicals open) and voltage gated (change in membrane potential opens)

when open voltage gated channels change the membrane potential and thus are responsible for AP

maintains greater Na+ concentration outside the cell and greater K+ inside

uses alot of energy

AP conducted slow

AP in one part of cell membrane stimulates local currrents in adjacent parts of cell membrane that then produce an AP

AP conducted along entire axon

AP at one node of ranvier causes a local current to flow throught the surrounding extracellular fluid and through the cytoplasm of the axon to the next node stimulating the AP at the node of Ranvier

AP "jump" along length of axon = faster

junction where the axon of one neuron interacts with another neuron or with cells of effector organs

binding of neurotranmitters from the postsynaptic membrane to the postsynaptic membrane can either inhibit (K+ or Cl- channels open the inside of the postsynaptic cell tends to become more negative or hyperpolarized) or stimulate (Na+ channels open the postsynaptic cell becomes depolarized) the action potential.

local current

(muscle and nerve cells)

movement of Na+

when a stimulus is applied to a muscle/nerve cell following the resulting neurotransmitter activation of chemically gated channals, Na+ channels open briefly allowing Na+ to difuse into the cell 

inside of cell becomes positive (depolarization) resulting in local potential

action potentials occur in all or nothing fashion but what determins if the AP is all or nothing?

(muscle and nerve cells)

after a stimulus has caused chemically gated channals to allow Na+ to move in (local current) and depolarize the membrane (+) resulting in a local potential

the local potential can either continue or stop depending on if the depolarization was strong enough or not

if depolarization is strong enough the local potential will reach a threshold causing Na+ gated channels to open (axon of hillock, near cell body) causing 600-fold increase in permeability to Na+ (K+ also opens), reversal in charge occures (inside +)...channels reverse Repolarization and hyperpolarization occures briefly

acetylcholine (ACh)

neurotransmitter

released from CNS synapses, ANS synapses and neuromuscular junctions

effect: excitatory or inhibitory

autonomic neurotransmitter

released: selected CNS synapses and some ANS synapses

Function: excitatory

autonomic neurotransmitter

released: CNS synapses

Effect: generally inhibitory

released: selected CNS synapses and some ANS synapses

Function: inhibitory

released: CNS synapses

function: inhibitory

release: CNS synapses

Function: inhibitory

Released: descending pain pathway

Function: inhibitory

basic functional unit of the nervous system

sensory receptor, sensory neuron, interneurons, motor neuron, and effector organ

occur in the spine or brainstem and the simplest dont include interneurons

many presynaptic action potentials needed to cause an effect.

spatinal summation: local otentials originate from different locations on the postsynaptic neuron (from converging pathways)

Temporal summation: local potentials overlap in time

both can either inhibit or stimulate

foramen magnum at base of skull to second lumbar vertebra

end by 2nd lumbar vertebra is called the cauda equina (looks like a horse)

Ascending: consists of axons that conduct AP toward brain (prefix spino-) most consist of 2-3 neurons and end in the thalamus (spinothalamic  and dorsal column takes AP from thalaumus to cerebral cortex)

Descending: away from brain, named based on origin and termination. Direct extend directly from upper motor neurons in teh cerebral cortex to lower motor neurons in spinal cord (lateral and anterior corticospinal)

indirect no direct connection between cortical and spinal neurons (rubrospinal, reticulospinal, vestibulospinal and tectospinal)

grey matter H with posterior, anterior and lateral horns

sensory axons in dorsal root

motor axons in ventral root

somatic and autonomic neurons lay side by side in spinal nerve

arise along the spinal cord from the union of the dorsal roots and ventral roots

contain axons of both sensory and somatic motor neurons (dubbed mixed nerves)

exit vertebral column between adjacent vertebrae

31 pairs

three plexuses: Cervical (C1-C4), Brachial (C5-T1), and Lumbosacral (L1-S4)

spinal nerve

Phrenic

(neck and diaphragm)

 spinal nerves

axillary

radial

muscolocutaneous

ulnar

median

spinal nerves

obturator

femoral

tibial

common fibular

midbrain 

pons

medulla oblongata

contains several nuclei involved in vital body functions (heart rate, blood pressure, breathing)

minor damage can cause death

part of brainstem

continuous with spinal cord

regulates heart rate, blood vessel diameter, breathing, swallowing, vomiting, hiccupping, coughing, sneezing, balance

anterior surface exist two pyramids (descending nerve tracts)

part of brainstem

above medulla, bridge between cerebrum and cerebellum

breathing, chewing, salivation, swallowing

part of brainstem (smallest part)

above pons

coordinate eye movement, pupil diameter, turning head toward noise

dorsal consists of four mounds called colliculi (inferior: major relay centers for auditory nerve pathways in the CNS, superior: visual reflexes and receive touch and auditory output)

substantia nigra (black nuclear mass, regulates general body movement)

thalamus

epithalamus

hypothalamus

largest portion of diencephalon

influences mood and detects pain (unlocalized pain)

interthalamic adhesion connects the center of the two lateral parts

above and behind thalamus

emotional and visceral response to odors and pineal gland (function in the onset of puberty)

below thalamus

controls pituitary gland and is connected to it by infundibulum

controls homeostasis, body temp, thirst, hunger, fear, rage, and sexual emotions

mammillary bodies: postieror portion envolved in

emotional responses to odors and in memory

largest part of brain

fissures: deep indentations or sulci

sulci: superficial indentations

Gyri: folds on cerebral cortex that increase surface area

frontal lobe: front: voluntary motor functions, aggression, moods, smell

top: evaluates sensory input such as touch, taste, and pain

occipital lobe: vision

temporal lobe: hearing,smell, memory

cerebral cortex: surface of cerebrum composed of gray matter

controls thinking, communication, remembering, understanding, and initiates involuntary movement

lower part of brain by brain stem (the comparator-sensing device comparing data fom tow sources, motor cortex and peripheral structures)

cortex is composed of gyri, sulci, gray matter

it controls balance, muscle tone, coordination of fine motor movement (closing eyes)

white matter on inside

drinking stops cell firing this is why a drunk person cant find thier nose with thier eyes closed

cerebellar peduncles connect to brainstem and provide communication between cerebellum and other parts of the CNS

where ascending tracts project

where sensations are perceived

 in cerebral cortex

primary somatic sensory cortex (general sensory area)

in the frontal lobe

control voluntary motor movement

AP created here will control voluntary movement of skeletal muscles

premotor area-decides which muscles to contract

prefrontal area-motivation and foresight to plan and initiate movements

corpus striatum: within cerebrum

substantia nigra: midbrain, darkly pigmented cells

important in planing, organizing and coordinating moto movement and posture

diseases: parkinson, huntington and cerebral palsy

measured by electroencephalogram (EEG)

alpha: resting but awake

beta: mental activity

theta: child resting or adult during frustration

Delta: deep sleep in infants...signals epilepsy in adults

three connective tissue membranes surrounding and protecting the brain and spinal cord

epidural space (epidural anethesia) in spine only

dura mater (superficial and thick)

subdural space (spinal block and spinal tap-small amount serous fluid)

arachnoid mater (thin)

subarachnoid space (CSF and blood vessels)

pia mater (lightly bound to brain and spinal cord

thickest and most superficial layer of the menings

two layers-dural folds and dural venous sinuses

folds: extend into longitudianl fissures between the cerebrum and cerebellum, hold brain in place within the skull

sinuses collect blood from small veins of brain and empty into the internal jugular veins to exit the skull

fluid filled cavities of the CNS

lateral: large in each hemishpere

third: smaller midline cavity in center of diencephalon between thalamus halves and connectef by foramina to the lateral ventricles

fourth: base of cerebellum and connected to third by narrow canal (cerebral aqueduct) and also the subarachnoid space of the spinal cord

central canal: fourth continuous with it

bathes brain and spinal cord, providing a protective cushion around CNS

produced by choroid plexus in the ventricles

from lateral ventricles to 3rd ventricle through cerebral aqueduct to 4th ventricle then enters the subarachnoid space and also some into the central canal of the spinal cord. Finally it flows from the subarachnoid space to the arachnoid granulations in the superior sagittal sinus, where it enters teh venous circulation

preganglion are in lateral horn of spinal cord gray matter located between T1-L2 vertebre and exit through the ventral roots and into either sympathetic chain ganglia or collateral ganglia

postganglionic cell bodies in sympathetic chain ganglia or collateral ganglia

fight or fligh function: prepares body for physical activity

located in cranial nerves III, VII, IX, X and S2-S4 spinal nerves

postganglionic cell bodies in terminal ganglia or near or embedded in the walls of target organs

stimulates involuntary activities of the body at rest

sypathetic chain ganglia

(autonomic nervous system)

Collateral ganglia

(autonomic nervous system)

splanchnic nerves

(autonomic nervous system)

consists of plexuses within the wall of the digestive tract which include

sensory neurons that connect the digestive tract to the CNS

sypathetic and parasympathetic neurons that connect the CNS to the digestive tract

enteric neurons located entirely withing the enteric plexuses

capable of independently monertering/controlling digestiong tract however the two generally work together

epithelium

papilla: enlargments on the surface of the tongue

taste bud

supporting cell

taste cell

taste hair: where molecules or ions bind to receptors to initiate AP

taste pore

AP to insula of cerebral cortex

influenced by olfaction

auricle

external auditory canal

tympanic membrane (vibrates)

malleus strokes incus that moves foot plate of the stapes (which vibrates in the oval window)

inner ear; perilymph in scala vestibuli vibrates causing vestibular membrane to vibrate and thus

endolymph of cochlear duct which displaces the basilar membrane

cilia of hair cells (of spiral organ) detects movement of (hairs attached to) basilar membrane

AP in cochlear nere

auditory cortex

auricle

external auditory canal

ceruminous gland (produces cerumen or earwax)

tympanic membrane (eardrum, separating external ear from middle ear) thin layer of connective tissue sandwiched between two epithelial layers

oval window and round window connect middle ear with inner ear

three ossicles: malleus (hammer-attached to medial surface of tympanic membrane), incus (anvil-connects), stapes (stirrup-base set in oval window surrounded by flexable ligament) amplifiction center

these bones transmit vibrations from tympanic membrane to oval window

muscles attaced to malleus and staples dampen sound to protect inner ear structures

two unblocked openings one to the mastoid process of temporal other auditory tube, opens to pharyns and enables air pressure to be equalized between outside and middle ear cavity (unbalance = hard to hear)

interconnecting tunnels and chambers in the temporal bone-bony labyrinth

three sections:

cochlea-shaped like a snail shell contains a bony core shaped like a screw with threads called spiral lamina which has three parts:

scala vestibuli:extends from the oval window to the apex of cochlea

scala tympani-extends parallel to scala vestibuli from apex back to round window

cochlear duct: space between vestibular membrane and basilar membrane (endolymph)

vestibular membrane- balance

semicirular canals- dynamic equilibrium/balance

membranous labyrinth is the smaller membranous tunnels inside the bony labyrinth (filled with clear fluid-endolymph)

perilymph fills space between bony labryinth and membranous labyrinth

static equalibrium-associated with vestibule (evaluating position of head relative to gravity)

Dynamic equilibrium-associated with semicirular canals and involved in evaluating changes in direction and rate of head movement