Physiology Exam 2

describe the different parts of a neuron

A = dendrites

B = cell body

C = Axon Hillock

D = Axon

F = axon terminal

nervous system organization

Central nervous system — brain + spinal cord (integration center)

Peripherial nervous system — crainal & spinal nerves

define afferent neuron, efferent neuron, & interneuron

afferent = SENSORY

• conduct impulses INTO CNS →

efferent = MOTOR (2 types)

• conduct impulses ← OUT CNS

• 1. somatic — voluntary / reflex

• 2. autonomic — involuntary

interneuron = CNS neuron in between afferent & efferent

the flow of information in a neuron

1. sensory receptor detects something is happening

2. sends a information up the AFFERENT neuron

3. signal reaches CNS thru an interneuron

4. CNS sends signal down the EFFERENT neuron

5. reaches effector organ to carry out the movement

what are the effects of myelination on a neuron

can send signal much faster

allows it to skip thru axon in nodes of ranvier

different types of neurons & functions

1. afferent

2. efferent

   1. somatic

   2. autonomic

3. interneurons

different types of neuroglial cells & functions

supporting cells

1. shwann cells — PNS & MYELINATE PNS

2. oligodendrocytes — CNS & MYELINATE CNS

3. astrocytes

4. microglia — phagocytic

5. ependymal cells — line the CNS

difference in the PNS & CNS for neural regeneration

CNS — doesnt regenerate

PNS — can regenerate from schwann cells

how is an AP produced

excitable tissue

compare & contrast action potentials & graded potentials

graded: doesnt reach threshold

A.P.: able to reach threshold and continue w/ stimulus

characteristics of graded potentials

can be either depolarizing or hyperpolarizing

never reaches threshold

decremental (decreases)

how are action potentials conducted & characteristics of them

they reach threshold (-50 @ axon hillock)

not decremental (always the same magnitude)

all or none

describe the refractory period

absolute: cannot make more AP

• either when Na+ channels are open / inactivated

• prevents overlap of signals

relative: can send another AP

• but you need a STRONGER stimulus & to get this you need higher frequencies of AP

• hyperpolarized, more difficult to get it to threshold

define depolarization

less negative (than -70)

Na+ channels opening → Na+ rushes IN

define repolarization

returning back to RMP (-70)

Na+/K+ pumps maintain this process

define overshoot

when the membrane potential goes above 0 mV & becomes POSITIVE

define hyperpolarization

more negative (than -70)

Na+ channels inactivated & K+ channels activate → K+ rushes out

permeability of K+ & Na+ during AP & how does this change affect membrane potential

depolarization = Na+ most permeable & K+ least permeable

repolarization = Na+ least permeable & K+ most permeable

Na+ v. K+ gating channels

Na+ VOLTAGE gated channels

• open: during depolarization

• inactivated: during peak of AP

• closed: at rest

K+ Voltage gated channels

what does “all or none” principle for AP

its either at threshold or it is not

what is saltatory conduction

when action potentials jump thru rodes of Rav.

dont happen in myleine

electrical v. chemical synapses

Electrical synapse

• Cells are directly connected

• Signal passes straight from cell to cell

• Very fast

• Uses gap junctions

• Electrical = direct + fast

Chemical synapse

• Cells are NOT directly connected

• One cell releases a neurotransmitter

• Neurotransmitter crosses the small gap to the next cell

• Slower than electrical

what does propagation mean

moving down the axon

what is the sequence of events in neural communication across a synapse

1. Action potential reaches terminal end of the presynaptic neuron

2. triggers Ca2+ to rush IN thru Ca2+ voltage gated channels

3. Ca2+ triggers neurotransmitters to get exocytosed out synaptic vesicles

4. neurotransmitters bind to ligand gated channels on the POSTsynaptic neuron

5. induces synaptic potential & causes Na+ to rush in

   1. can cause the next neuron to send or inhibit AP

excitatory v. inhibitory postsynaptic potentials

EPSP — less negative / depolarize (Na+ rushes IN)

• can be strong enough to reach threshold & AP forms on postsynaptic cell

IPSP — more negative / hyperpolarizes (Cl- rushses IN)

• more difficult to send AP and reach threshold

• GABA opens ligand gated channels

differentiate: temporal v. spatial summation

WILL ALWAYS BE EXCITATORY

temporal: if 1 presynaptic input sends multiple outputs to reaches threshold

spatial: if +2 send a signal at SAME TIME, they get added together to reach threshold

what is a ligand gated channel

where neurotransmitter binds to

compare: actions of an excitatory neurotransmitter & an inhibitory neurotransmitter on the POST synaptic neuron

mechanically gated channel:

excitatory — opens Na+ channels & rushes in → depolarize & can reach AP

inhibitatory — opens Cl- channgels & rushes in → hyperpolarize & cannot reach AP

action of acetylcholinesterase

breaks down acetyl choline & found in synaptic cleft

contains neurotransmitter reuptake receptor

how do G protein coupled signal pathways produce synaptic potentials

polar molecule binds to receptor

G proteins released

G protein binds to channel

opens channel

describe protection of the CNS

bone is the thickest layer & outermost layer

meninges: 3 layers

• dura mater by bone = solid matter

• arachnoid matter = middle

  • subarachnoid space

• pia mater = directly on the brain

what is the function of cerebral spinal fluid (CSF)

buoyancy

protection

maintenance of chemical environment

what produces CSF

epidenmal cells

what connects the right & left hemisphere

corpus callosum

what are the 5 lobes of the cerebral cortex

what are the function of all of them

1. occipital — VISUAL

   1. perception and interpretation of visual images

2. temporal — AUDITORY

   1. perception & interpretation of auditory info

3. parietal — SENSORY

   1. somatosensory — receives info

   2. perception of senses

4. frontal — MOTOR

   1. voluntary movements

   2. executive reasonings

5. insula — VISCERAL RESPONSES

   1. deepest layer / on inside

what divides the frontal and parietal lobe

precentral gryus — frontal

postcentral gryus — parietal

functions of the right hemisphere v. functions of the left hemisphere

which one is dominant

Right — depth perception (visuospatial) & patterns/reading maps

Left — language & analytical ability

• THE MOST DOMINANT

what is the difference between broca’s area v. wernicke’s area

brocas area: frontal lobe

• fine motor functions involved in speech

wenickes area: in between pariteal/occipital/temporal region

• hearing & understanding language

• formulating words

what is aphasia?

• broca’s aphasia

• wernicke’s aphasia

aphasia: a brain-related language disorder that makes it hard to speak/understand speech/read/write

• Broccas Aphasia: cannot talk/difficult responding BUT can understand what is spoken

• Wernickes Aphasia: cannot understand spoken/written language BUT can speak using made up words

what are the different types of memory

Memory:

1. short term: <30 sec

2. long term: >30 sec

   1. non-decalarative: memory of simple skills (ex: tying shoes)

   2. declarative: memory of facts & events (ex: where were you…?)

what are the different types of memory consolidation

temporal lobes (amygdala & hippocampus) involved in converting short term → long term

• sleep is needed for this

STRESS IMPAIRS THIS

locations & functions of the thalamus & hypothalamus

location: diencephalon

functions:

• body temp

• thirst & urine

• food intake

• pituitary hormone

• circadian rhythm

• control ANS

what are the structures & functions of the midbrain

motor movements of the eye

auditory processing

what are the 2 proteins that impact alzheimers disease

1. beta amyoild plaques

2. tau

these both inhibit & alter movement of ions

what are the structures & functions of the brainstem

critical link between between spinal cord & higher brain regions

vegetative funcitons = involuntary functions that keep you alive

made up of:

1. midbrain (top) — eye movement

2. pons — relay information station

3. medulla (bottom) — basal survival functions (breathing, heartbeat, dilation of blood)

function of the cerebellum?

planning, initiating, & timing motor movements

learning skilled motor tasks

ataxia

damage to cerebellum

UNCOORDINATED MOVEMENT

function of the limbic system

hippocampus + amygdala

• emotions

• aggression

• fear

• smell

• goal directed behavior

what are the structures & functions of the reticular activating system

Structure: midbrain, pons, medulla

Fire to keep you awake & brain awake

• inhibited: brain isnt awake

phases of sleep?

REM — rapid eye movement // eyes moving very fast

• brain is buidling memories

Stages:

1. go into sleep

2. longer & deeper stage & body temp drops

3. GOLDEN STAGE = want to be here& body is repairing

4. cycling back to REM

what is the difference between: ascending v. descending tracts of the spinal cord

ascending: dorsal root

• carry sensory information UP to brain (afferent)

ascending: ventral root

• carry motor information DOWN to effector (efferent)

structures of the spinal nerve v. neural pathways of the reflex arc

PNS

all are mixed nerves: sensory & motor

• dorsal root = sensory (afferent pathway)

• ventral root = motor (efferent pathway)

Pathway:

1. stimulus is detected thru receptor neuron →

2. receptor sends singal thru dorsal root

3. signal enters intregating center (interneuron)

4. response gets sent thru ventral root

5. signal gets to effector & a response happens

what are the components of the withdrawal reflex

nociceptor detects pain

AP goest thru afferent pathway

hits integration center

AP sent by integration center thru efferent pathway

stimulates motor control

• stimulate flexors

• inhibits extensors

classification of cranial nerves

part of the PNS

12 pairs

what are the divisions of the efferent division of the PNS

1. somatic nervous system — voluntary

   1. pre&postsynaptic

2. autonomic nervous system — involuntary

   1. pre&postganglionic

organization of the AUTOnomic motor neurons

both are on, but which one is innervating MORE

sympathetic: stress

parasympathetic: rest

what is the structure of the sympathetic nervous system

• ganglia

• preganglionic v. post ganglionic

• pathway

thoracolumbar region

SHORT pre & LONG post

preganglionic release acetyl choline & bind to nicotinic receptors on post

Postganglionic release norepinenorepinephrinephrine into adrenergic receptors on effector

what is the relationship between the sympathetic nervous system & adrenal medulla

modified part of the sympathetic system

preganglionic fibers secrete hormones into BLOOD

• more epinephrine > compared to norepinephrine

structure & innervation pathways of the parasympathetic division of the ANS

craniosacral region

LONG pre & SHORT post

preganglionic release acetyl choline & bind to nicotinic receptors on post

Postganglionic release acetyle choline into muscarinic receptors on effector

cholinergic receptors v. adrenergic receptors

cholinergic receptors = nicotinic & muscrainic

• parasympathetic

adrenergic receptors = nicotinic & adrenergic

• sympathetic

what are the effects of adrenergic stimulation on different organs & what are the different types of receptors involved

Alpha & beta receptors on SYMPATHETIC

• release NE & epinephrine

how does albuterol work in ANS

b2 agonist = BETA = sympathetic

inhaling N.E.

how does atropine work in ANS

blocks muscrainic receptors = parasympathetic

dilate pupils

how does beta-blockers work in ANS

block beta-adrenergic receptors

• sympathetic

antagonistic & cooperative actions of the sympathetic & parasympathetic divisions of the ANS

parasympathetic & sympathetic work in OPPOSITION = ANTAGONISTIC

• EX: parasympathetic = increase heart rate & sympathetic = decrease heart rate

cooperative effects: saliva & urination

what innervates an organ without dual innervation

ONLY SYMPATHETIC (increase or decrease)

EX: sweat glands

explain the term sensory transduction

converting a stimulus into an electrical signal (AP) so the brain can understand it

phasic v. tonic receptors

tonic: CNS is continually getting info

• dont adapt

• or adapt slowly

• you know & understand the stimulus is there

phasic: you forget the stimulus is there once applied, but remember its there when its gone

• constantly adapt

• touch receptors in the skin

describe the nature & significance of the receptor potential

electrical change that happens in a sensory receptor when it senses a stimulus

can lead to an AP

influx of Na+ can produce receptor potentials

differentiate between sensation v. perception

sensation: collection of info (RECEPTORS)

perception: interpretation of what is sensed (where AP are sent)

4 steps of perception

1. stimulus

2. transduction: converting stimulus → AP

3. conduction: axons; conducting AP/electrical signals

4. perception: integrating center

define sensory acuity & explain factors that affect acuity

sensory: ability to tell two things apart when touching you

high: able to tell very specifics

low: able to tell general area

affect:

• field size

• # of receptors

• area of somatosensory

what are the different types of sensory receptors

• photoreceptors - light

• mechanoreceptors - mechanical energy

• thermoreceptors - temp regulation

• osmoreceptors - osmolarity

• chemoreceptors - specific chemicals

• nociceptors - pain

• proprioceptors - position of your body

• externoreceptors - outside your body

• interoreceptors - inside your body

what are cutaneous sensations

temp, touch, pressure, pain

contralateral - terminates here

what are the modalities of taste

chemoreceptors detect taste — housed in taste buds

tastant: taste chemical that dissolves thru salvia

1. salty — caused by chemical salts (NaCl)

2. sour — caused by acids

3. sweet — caused by glucose

4. bitter — caused by chemically diverse group of tastants

5. umami — savory taste

how is taste produce + conveyed in the brain

produce: binding of tastant w/ receptor cell & produces receptor potential

brain: insula detects gustatory & somatosensory cortex moves tongue

how do odorant molecules stimulate their receptors (polarity?) & how the information is conveyed to the brain

odorants — chemcial molecules that can be smelled

• POLAR = water soluble solvents that dissolve into mucus layer & stimulate the olfactory bulb by binding to MEMBRANE bound receptors

smell reaches the limbic system & thats how you form memories w/ smells

describe hertz

number of cycles / second

what are the structures of the vestibular apparatus & how do they function to produce a sense of:

• balance

• equilibrium

• position of the head

1. semicircular canals - ROTATIONAL MOVEMENT

   1. anterior canals: head moves forward / back (nodding)

   2. posterior canals: head is tilting left / right

   3. lateral canals: spinning

2. otolithic organs - LINEAR MOVEMENT

   1. utricle: left & right

   2. saccule: up & down

what are the semicircular canals

bending of hair cells embedded in cupula = KINOCILIUM

what are the otolithic organs

utricle - horizontal (moving forward/backward) or left/right

saccule - vertical (up/down)

contain otoliths - crystals found in gelatinous substance that provides mass & helps move against gravity

neural pathways of the vestibular system

input: goes to vestibular nuceli in brain

cerebellum helps w/ balance

how do sound waves result in movements of the oval window & the basilar membrane

sound wave travels thru → hits the tympanic membrane → malleus → incus → stapes → hits oval window → oval window causes perilymph fluid to move in cochlea → fluid causes basilar membrane to deflect → the hairs on the basilar membrane move → sends AP

low pitch v. high pitch

• higher frequency (#) = higher pitch

• lower frequency (#) = lower pitch

soft sound v. loud sound

• soft sound = smaller amplitude (height)

• louder sound = larger amplitude (height)

how are loudness & pitch discrimminated

pitch:

• low = distal (further) = helicotrema

• high = against oval window (closer)

loudness

• soft = hairs bent softer & closer

• louder = hairs bent harder & further away = helicotrema

what are the structures of the eye

sclera - white portion of eye

cornea

iris - colored portion

pupil - black

vitreous humor - makes the shape & inside cell

aqueous humor - carries nutrients for cornea & lens

retina - rods & cones

how do the structures of the eye focus light onto the retina

1. cornea - where light first enters thru and bends

2. iris - controls the amount of light entering eye by changing pupil size

   1. circular muscle

   2. radial muscle

3. pupil - light passes thru here; doesnt move,, hte iris around it moves & adjusts the size

4. lens - changes shape helps to refract light on retina

   1. flattens - near

   2. rounder - far

5. retina - rods and cones

what is refraction

bending of light as it moves thru areas

cornea does this

what is accomodation

changing shape of lens for near/far away items

how to direct the bent light into eye

how is accommodation at different distances accomplished?

is this parasympathetic, sympathetic, or dual innervation?

REFRACTION OF LIGHT THRU ACCOMMODATION

near items: lens becomes rounder → parasympathetic INCREASES

• ciliary muscles contract

• suspensory ligaments slacken

far away items: lens becomes flatter → parasympathetic DECREASES

• ciliary muscles relax

• suspensory ligaments get pulled

how does the iris innervate & change

HOW MUCH LIGHT ENTERS

contains 2 muscles

• circular muscle: CONSTRICT via parasympathetic nervous system

  • INNERMOST AREA

  • becomes smaller in bright light

• radial muscle: DILATES via sympathetic nervous system

  • OUTERMOST AREA

  • becomes larger in dim light

common disorders of:

• refraction

• glaucoma

• cataracts

cataracts: opacity of lens

glaucoma: increased pressure of built up aqueous humor in eye, causes damage to optic nerve

refraction:

• myopia: nearsighted

  • unable to see far things

  • lens is too long, you need concave lens

• hyeropia: farsighted

  • unable to see close up things

  • lens is too short, you need convex lens

• presbyopia: stiffness of lens as you age

  • decrease in accomodation

what are the 3 layers of the retina

1. outermost layer = RODS & CONES

2. middle layer = bipolar cells

3. inner layer = ganglion cells

how does light affect rods & cones

outer segment detects light, inner segment = mitochondria, & synaptic terminal is where they release neurotransmitter

• rods = night/gray colors

• cones = day/color

describe dark & light adapatation

DARK:

• AT PHOTORECEPTOR:

  • Na+ channels open

  • release neurotransmitter = GABA

• GABA inhibits bipolar cell

• No EPSP

• No AP sent = cannot view anything in dark

LIGHT:

• AT PHOTORECEPTOR

  • light closes Na+ channels

  • membrane becomes hyperpolarized & doesnt allow GABA to be sent

• because GABA isnt sent, bipolar & ganglion cells can send messages

• become EPSP →

• there is AP in visual cortex & you are able to see light

compare the functions of rods & cones

(photopigments)

similarities:

• consists of 2 components — opsin & retinal

  • opsin = protein that retinal binds to

  • retinal = absorbs light

    • cis or trans

Differences:

• 4 different types of photopigments

  • rods (1) = rhodopsin

    • absorbs all visible wavelengths

    • gray colors

  • cone (3) = red, green, blue

rods v. cones:

• which has higher sensitivity & lower sensitivity

• which has higher acuity & lower acuity

Rods: higher sensitivity because it has more receptors & low acuity

• receptors CONVERGE into 1 pathway

• larger number of receptors but they all converge

Cones: higher acuity because each cone has their own receptor / does not converge & low sensitivity

• no convergence happening

• receptors are their own individual one

• smaller # of receptors

what is the importance of the fovea centralis

contains rods and cones

vision is best at fovea centralis

how is color perceived

depends on the amount of cones you have

• red is the longest wavelength

• green is middle

• blue is shortest wavelength

the color you see is the light that is being reflected