Biol 319 exam 4 Lee

Some of our "neuro" material we have been talking about from day one, so please do not overlook subjects such as:term-163

Neuron vs nerve, Nervous tissue as an excitable tissue, etc.

neuron

single nervous system cell

nerve

bundle of axons (neurons)

nervous tissue is excitable

-generate AP from RMP

-excitable=allow signals to transmit fast, immediate response to stimuli

3 major sections of the brain

hindbrain, midbrain, forebrain

forebrain

prosencephalon

A. -Diencephalon: thalamus, hypothalamus,

-epithalamus, pineal gland=melatonin

B. Telencephalon = cerebral hemispheres (cortex), basal nuclei and limbic system

Midbrain

Mesencephalon-Reticular Activating Centers (RAC)= Wakefulness (caffeine (adenosine receptor antagonist) hits receptors here)

hindbrain

rhombencephalon (brain stem - medulla and pons)

Medulla oblongata: Heart rate, breathing rate, blood pressure, blood flow, vomiting, swallowing

Pons: balance & posture (also cerebellum)

Cerebellum: coordination, intricate movements, spatial equilibrium

Reticular Activating Centers function

a network of neurons that regulate sleep-wake transition and arousal

Reticular Activating Centers location

-brainstem (above the spinal cord)

-midbrain

Reticular Activating Centers neurotransmitters

acetylcholine, serotonin, dopamine, histamine

Medulla Oblongata

controls HR,BP,RR,blood flow swallowing,and vomiting

Sulcus

depression=increase in surface area=greater number of neurons that can be packed into the cerebral cortex

fissure

deeper and more prominent than a sulcus

location of central sulcus

between frontal and parietal lobes

Location of longitudinal fissure

The space between the right and left hemisphere. It is located in the cerebral cortex. It divides the cerebral cortex.

Brainstem

medulla oblongata, pons, midbrain

the brainstem connects

brain and spinal cord

Cerebellum

coordination, muscle tone, & spatial equilibrium

Female brain vs male brain

-female brain is better at multitasking

-increase in corpus callosum

-increase in synapse connections

substantia nigra (black substance)

Basal ganglia structure in mid brain

a modulator for the pyramidal tracts which is the main pathway for voluntary movement being sent to the spinal cord

substantia nigra produces

dopamine which helps fine-tune movement signals sent by pyramidal tracts

Parkinson's disease

dopamine-producing neurons are lost in the substantia nigra, which means pyramidal tracts can't send out signals properly, resulting in impaired motor control (tremors)

pyramidal tracts

-of the midbrain

-looks like pyramids

Limbic System: Amygdala

-also known as paleomammalian cortex (old)

-made up of the amygdala (plays a role in memory, decision making, and emotional responses), mammillary bodies, stria medullaris, ventral nuclei of gudden

-interacts with basal ganglia (see something scary)

-processes and regulates emotions, behaivors, motivation, forming memories, influence autonomic nervous system (includes HR and BP), playing a key role in fight or flight or sympathetic system

Why is it important that we have an emotional response and brain re-wiring when experiencing something scary?

it gets you ready to either face the threat or escape from it (fight or flight; sympathetic NS)

Lobes of the brain

frontal lobe, parietal lobe, occipital lobe, temporal lobe

frontal lobe

voluntary movements, voluntary thought, cognition, thinking, engaging in reason/cause-effect, long-term memory, personality

parietal lobe

PMC (primary motor cortex - taste, temperature, touch, ) PSSC (Primary somatosensory cortex- pressure, vibration detection)

occipital lobe

vision

temporal lobe

short-term memory, emotions, speech, smell (olfaction), auditory stimuli

cerebellum

balance and posture (also pons works with this), muscle tone, coordination→spatial equilibrium

midbrain function

alert, awake, conscious

pons

balance and posture (also cerebellum works with this)

spinal cord

reflexes, walking, urination, sex organ function

Primary motor cortex

-anterior

-controls voluntary muscle movements

somatic sensory cortex

-posterior

-receives and provides sensory information from the body

the central sulcus divides

the primary motor complex and the somatic sensory complex

Hypothalamus

Part of the diencephalon in charge of body homeostasis, temperature regulation, endocrine functions, metabolism, circadian rhythms

6 functions of the medulla oblongata

BP,HR,RR,Blood flow, vomiting, swallowing

cerebrospinal fluid function

"cushion" the brain and provide nutrients

cerebrospinal fluid location

-in/around the brain and spinal cord

-within the ventricles of the brain

-subarachnoid space between the arachnoid matter and the pia matter

Meninges

-the dura matter, arachnoid matter, and the pia matter

-protect CNS

Meningitis.....bones......pressure......If they find WBCs in the CSF.....

If WBC's are in CSF then that could signify meningitis

meningitis

inflammation of the meninges of the brain and spinal cord

effects of meningitis

-purulent labrynthitis

-deteriorates the organ of Corti

-can cause ossification of the cochlea

-severe-to-profound sensorineural hearing loss

signs of meningitis

high fever, stiff neck, drowsiness, and intense headache; may progress to coma then death within hours of onset

caines

mepivacaine, ropivacaine, levobupivacaine, chloroprocaine

opioids

fentanyl, morphine, hydromorphone, oxycodone, sufentanil

*** Neuro-pharmacology in general!! ***

local pain blockers and systematic pain blockers

local pain blockers

-anaesthetics

-"caine" blocks VG Na+ so that there is no depolarization and no signal at the source of pain (signal never sent to brain)

systematic pain blockers

-opiates/narcotics

-lead to pleasure/reward pathways

-FLATPEG

-E= endorphins,endrogenous

**** "-caines"; narcotics/opiates; SSRIs vs SRIs

Selective Serotonin Reuptake Inhibitors (SSRI)- legal, block serotonin from going back home (brain) causes us to feel happy (antidepressants) only blocked in brain and this a slow process

Serotonin Reuptake Inhibitor (SRI) - not legal, Amphetamines - 3,4 MDMA also known as molly ooooo drugs,

Caines - Fast voltage gated Na+ channels, these will block the depolarization/ signal before it occurs and its localized

Opoids/Narcotics - Doesnt care as it will block all signals and hyperpolarize causing no processing of any pain signals. This is not localized and it is all over the body

SSRI

-take a long time to be effective (2-4 weeks)

-selective serotonin reuptake inhibitor

-selective=only in brain

-elevates serotonin levels in brain

drug examples of SSRI

Zoloft (generic: sertraline), Prozac (fluoxetine), Lexapro (escitalopram)

SRI

-works very fast and short-term

-serotonin reuptake inhibitor

-illegal

-blocks all over body

-leads to feedback inhibition

-body stops production

-elevates dopamine levels in brain (plays into addiction centers in brain) because fast dopamine hit = brain happy -> brain wants easy happy feeling more)

examples of SRI

methamphetamine

both SSRi and SRi elevate

mood (dopamine and serotonin)

Proprioception...inner ear fluid....CN VIII....

-Vestibulocochlear Nerve (CN VIII)

- the semicircular canals of the ear have fluid that plays a role in balance in detection of acceleration/ deceleration

Cranial nerves

olfactory nerve I, optic nerve II,Oculomotor nerve III, Trochlear IV, Trigeminal Nerve 5,Abducens nerve VI, Facial Nerve VII, Vestibulocochlear nerve VIII,Glossopharyngeal nerve IX, Vagus nerve X, Accessory nerve XI, Hypoglossal nerve XII

Olfactory nerve I

-Larger in vertebrates with a better sense of smell

-Proprioception is a sensory function

-Smell and taste are linked and are both chemoreceptors

-Smell is linked to memory

-issues (lesions) - inability to smell

Optic Nerve II

-Vision

-Optic chiasm: part of the brain where optic nerves cross

-Vision centers are in the occipital lobe

-Issues = blindness on the affected side

Oculomotor nerve III

-Double vision and blurred vision and drooping eyelids (ptosis)

-Superior, inferior, medial rectus and inferior oblique = proprioceptive

-Parasympathetic to the sphincter of the pupil(constriction) and ciliary muscles (accomodation)

Trochlear Nerve IV

-Superior oblique, motor and proprioceptive

-Some of the smallest motor units are found within the muscle of the eye

-Lens mineralize= cataract

-Double vision

Trigeminal Nerve V

-Mastication = chewing (mainly V3)

V1 - Ophthalmic - sensory from nose to scalp

V2 - Maxillary - sensory from upper jaw to upper lip

-V3= mandibular branch = masseter, temporalis, medial and lateral pterygoids

-issues include Trigeminal neuralgia - intense pain along the course of branch of nerve; loss of tactile sensation in face or weakness or clenching jaw

Abducens Nerve VI

-Double vision

-Lateral rectus

Facial Nerve VII

-Facial expressions

-Facial palsy

-(facial palsy) -Loss of taste sensation on anterior 2/3 tongues = decreased salvation

Vestibulocochlear Nerve VII

-Semicircular canals of the ear have fluid that plays a role in balance and detection of acceleration/deceleration

-Cochlea play a role in hearing

-Lesions = loss of hearing (cochlear nerve), loss of balance and equilibrium; nausea, vertigo and vomiting (vestibular nerve)

Glossopharyngeal Nerve IX

-Parasympathetic increases salivary gland secretion

-Motor to pharyngeal muscle

-Proprioceptive to pharyngeal

-Issues - difficulty swallowing loss of tase sensation posterior 1/3 of tongue; decreased salvation

Vagus Nerve X

-"To wander"

-Vagus nerve goes all over the body; Only nerve to extend beyond head and neck to visceral organs in thorax and abdomen

-Parasympathetic to SA node of the heart= HR down

-Remember, the SA node will fire twice per second without "vagal tone"

-Difficulty swallowing and/or hoarseness; uvula deviates away from side of the dysfunction

Accessory Nerve XI

-Most posterior

-Sternocleidomastoid

-Trapezius

-Issues are difficulty elevating the scapula or rotating neck

hypoglossal nerve XII

-"Under tongue"

-Intrinsic tongue muscles are entirely within the tongue

-Extrinsic tongue muscle attach the tongue to other structures

**Cranial nerves associated with vision ***

optic nerve II

**Cranial nerves associated with double vision ***

Oculomotor Nerve lll, Trochlear nerve lV, Abducens nerve Vl

Motor units are BACK on CN IV! Why the need for such small motor units associated with the eye??

-Smaller motor units create finer motion

-Smallest motor units are used in eye muscles (small movements and help with focusing sight)

sympathetic

-Regulates arousal and energy generation

-Fight or flight

-Stronger: hormone from adrenal medulla

-Thoraco-lumbar nervous system

parsympathetic

-antagonistic effects on target organs and promotes calming and a return to "rest and digest" functions

-default system

-Cranio-sacral nervous system

CN V - branches

-Ophthalmic (V1)

-Maxillary branch (V2)

-Mandibular branch (V3)

.....teeth.....dentist......"-caines"....This question is writing itself!!!

-Canines=local anesthesia

-Blocks voltage-gated sodium channels

-No depolarization

Both parasympathetic and sympathetic

PNS
-have pre and post-ganglionic

-Acetylcholine=pre and post NT

CNS

-Acetylcholine= ONLY post ganglionic

CN X.....parasympathetic.....heart rate.....NT (?)......NOT a nicotinic ACH

receptor....which means the same binding molecule can have different effects of different tissue...? And one's answer must be more than "a different receptor"!

-all over the body

-parasympathetic to SA (sinoatrial) node of the heart = HR down

-remember the SA node will fire twice per second without "vagal tone"

CN XI....muscles....medical condition

-sternocleidomastoid and trapezius

-difficulty elevating the scapula or rotating the neck

Graded Potential

-barrage of EPSPs

-determine if an AP is generated

-Na+, Cl-, K+

-summation

Action Potential

-transmit signals over long distances

-Na+, K+

-no summation

Leak Channel

-ion channel that is always open, allowing ions and substances to pass through

-aka passive channels or non-gated channels

Carrier

-membrane protein that moves molecules across a cell membrane

Pump

-generate a membrane potential by creating an electrochemical gradient across the membrane (against the concentration gradient)

LIGAND GATED RECEPTOR/CHANNEL

-protein embedded in a cell membrane that acts as a gate, allowing specific ions to pass through only when a signaling molecule (called a ligand) binds to it

-opening the channel by triggering a conformational change in the receptor protein

VG CHANNEL

-transmembrane protein that opens and closes in response to changes in a cell's electrical potential

sympathetic fibers

pre-ganglionic: short

post-ganglionic: long

sympathetic NTs

Acetylcholine is pre

sympathetic location of origination within spinal cord

thoracic and lumbar

why is sympathetic stronger?

due to release of Ach on adrenal medulla, which releases norepinephrine

Parasympathetic fibers

pre-ganglionic: long

post-ganglionic: short

Parasympathetic NTs

Acetylcholine is pre and post

Parasympathetic location of origination within spinal cord

sacrum and coccyx

Myelination....APCV

-Myelinated sheaths are faster sheaths

-Length doesn't matter (hence the myelination=saltatory conduction)

-BUT diameter does matter

-fastest ever recorded is 250mph

release of NT

Step 1: An AP arrives at the axon terminal

Step 2: voltage gated Ca2+ channels open and Ca2+ diffuses into axon terminal

Step 3: the calcium ions stimulate vesicles to release their NT via exocytosis

Step 4: The NT crosses the cleft via diffusion

Step 5: The NT binds to its receptors on the postsynaptic cell and causes chemical gated channels to open, iniating graded potential

Step 6: NT activities cease when:

a. neurotransmitter reuptake back into axon occurs

b. the NT diffuses away from its receptor

c. enzymes degrade or break up NT

Fate of NT

Can be enzymatically degraded

Ex) acetylcholinesterase: can be inhibited by SARIN nerve gas, ach levels for WAY up = intense skeletal muscle contraction

Part or all of the NT can be taken up by reuptake proteins on the presynaptic side

Ex) FE- SSRI- selective serotonin reuptake inhibitors, serotonin levels go up in the brain slowly and only in the brain

Sometimes NTs escape from the synapse and are usually scavenged by astrocytes

summation

-graded potentials between resting and threshold