AP 1 Lecture Exam 4

cells of the nervous system

neuroglial cells

neurons

hippocampus

forms longterm memories

where neurogenesis occurs

amygdaloid body

emotional response

aspects of emotion

reponse to fear

CSF formation

blood plasma is filtered from the blood capillaries across capillary wall and pia mater

its composition is modified by the ependymal cell as it moves through these cells

fluid is released into a ventricle and now referred to as CSF

types of neurons

sensory

motor

interneurons

types of neuroglial cells (of the CNS)

astrocytes

ependymal cells

microglial cells

oligodendrocytes

types of neuroglial cells (of the PNS)

satellite cells

neurolemmocytes

what does the CNS consist of

brain

spinal cord

what does the PNS consist of

nerves

ganglia

structure of cranial nerves (number of pairs)

structure of spinal nerves (number of pairs)

extend from brain (12 pairs)

extend from spinal cord (31 pairs)

functional classification of neurons

sensory neurons: contain sensory neurons sending sensory input from somatic or visceral receptor signals to CNS

motor neurons: contain motor neurons sending output from CNS to the somatic and autonomic (visceral) effectors

interneurons (association neurons): located in CNS receive sensory input from sensory neurons and inititates motor output to motor neurons

what is the structural unit of the nervous system

neuron is the unit

multipolar neurons

all motor neurons

*most interneurons

*multiple processes extend directly from the cell body; many dendrites and 1 axon; most common type of neuron

bioplar neurons

some sensory neurons

*2 processes extend directly from the cell body; 1 dendrite and 1 axon; relatively limited in where they are located

unipolar neurons

most sensory neurons

*single short process extends from cell body and looks like a T as a result of the fusion of two processes into 1 long axon

anaxonic neurons

interneurons

*only dendrites

*no axons

astrocyte function (CNS)

helps BBB

regulates interstitial fluid consumption

provides structural support and organization to the CNS

*assists with neuronal development

*alters synaptic activity

*replicates to occupy space of dying neurons

brings blood and oxygen to BBB

enpendymal cell function (CNS)

lines ventricles of brain and central canal of spinal cord

assists in production and circulation of the CSF

microglial cell function (CNS)

immunity cell (wandering)

*phagocytizes substances in the CNS

*protects the CNS by engulfing infectious agents and other potentially harmful substances

oligodendrocyte function (CNS)

myelinates and insulates CNS axons

*allows for faster action potential propogation along axons in the CNS

satellite cell function (PNS)

electrically insulates PNS cell bodies

regulates nutrient and waste exchange for cell bodies in ganglia

neurolemmocyte function (PNS)

myelinates and insulates PNS axons

allows faster action potential propogration along an axon in the PNS

neuronal pools

groups of neurons arranged in specific patterns

4 types of circuits

converging

diverging

reverberating

parallel-after-discharge

what happens in a coverging circuit

inputs converge at a signle postsynaptic neuron

*receives input from several presynaptic neurons

*ex: sights, sounds, smells of cooking → salivation

what happens in a diverging circuit

spreads information from one presynaptic neron to several postsynaptic neurons

*ex: walking, proper balance, posture, and motion

what happens in a reverberating circuit

use feedback to produce repeated, cyclical activity

*ex: breathing regularly while we sleep

what happens in parallel-after-discharge circuit

input transmitted simultaneously along several paths to a postsynaptic cell

*ex: involved in higher order thinking

what are neurotransmitters (4 steps in neurotransmission)

synthesized by neurons and stored within vesicles in synaptic knobs

released from vesicles when action potential triggers calcium entry into synaptic knob

binds to a receptor in a target cell

triggers a physiologic response in the target cell

4 classes of neurotransmitters

acetylcholine

biogenic amines (monoamines)

amino acids

neuropeptides

what are biogenic amines

what are the 2 types

amino acids that are slightly modified to synthesize the transmitter

1. catecholamines

ex: dopamine → tyrosine (amino acid)

2. indolamines

ex: seritonin → histodine and tryptophan

what is the sensory nervous system (afferent) responsible for

detecting stimuli by receptors and relaying information from the receptor to the CNS (ascending)

what is the sensory nervous system subdivided into

somatic sensory

*consicious perception (five senses and proprioreceptors)

visceral sensory

*subconcious perception (internal organs and blood vessels)

what is the motor nervous system (efferent) used for

controls effectors and is responsible for initating and transmitting information from the CNS to the effectors (descending)

what is the motor nervous system subdivded into

somatic motor

*initiates and transmits motor output from the CNS to the only type of effector that can be voluntarily controlled (skeletal muscles)

autonomic motor

*innvervates and regulates the other types of effectors that are involuntarily controlled (cardiac muscle, smooth muscle, and glands)

what is the stimulus/receptor (receptive segment) part of a neuron

dendrites and cell body

*binding of neurotransmitter released from presynaptic neurons; production of graded potentials

what is the control center (initial segment) of the neuron

axon hillock

*summation of graded potentials; initiation of action potential

what is the signal propagation (conductive segment) part of the neuron

axon

*propagation of action potential or sending end

what is the effector (transmissive segment) part of the neuron

synaptic bulb

*action potential causes release of neurotransmitter

function of myelin

faster propagation and efficeincy of action potentials along axons

acts as electrical insulation

current flow under myelin is very fast

what does action potentials involve and what law do they obey

action potential involves depoalrization (Na in) and repolarization (K out) and is propagated along the axon

they obey the all-or-none law because any voltage sufficient to open the voltage-gated channels initiates an action potential

what are graded (local) potentials

occur in neurons receptive region due to ion flow through chemically gated channels

can be positive or negative changes in charge

*have larger potential change to strong sitmulus

what is the nerve impulse in a neuron

action potential in a neuron

what is frequency in hearing

rate of vibrations (measured in Hz)

what is pitch in hearing

frequency of vibrating object

what are chemoreceptors

detect chemicals dissolved in fluid

*smell of food

*blood pH

what are proprioreceptors

detect stimuli within skeletal muscles, tendons, and joints that monitor body movement

*6th sense

what are baroreceptors

example of a mechanoreceptor that are within blood vessel walls and heart

*mechanoreceptor: detect physical deformation of the plasma membrance due to touch, pressure, vibration and stretch

what are rods

more numerous than cones

primarily located within peripheral retina

specialized in dim light, night vision

cannot distinguish color, lacks sharpness of vision

what are cones

less numerous than rods

primarily located within fovea centralis

respond to stimulation by bright light

specialized for color and recognition and sharpness of vision

subdivided into blue, green, and red cones

what is the general difference between sympathetic and parasympathetic

parasympathetic:

craniosacral, brings body to homeostasis in conditions of “rest-and-digest” and conserves energy and replenishes nutrient stores

*long preganglionic axon/short postganglionic axon

sympathetic division:

thoracolumbar, brings body to homeostasis in conditions of “fight-or-flight” and increases alertness and metabolic activities

*short preganglionic axon/long postganglionic axon

what are the sympathetic trunks

extends lateral to the vertebral column

appearance of pearl necklace

strings are bundles of axons, where pearls are sympathetic trunk ganglia which house cell bodies of sympathetic ganglionic neurons

what are white and gray rami communicantes

white and gray rami connect spinal nerves to trunk

white rami: entrance ramps for spinal nerves to trunk (myelinated preganglionic sympathetic axons)

gray rami: exit ramps from trunk to spinal nerves (unmyelinated postganglionic sympathetic axons)

what is the sensory pathway for 1st order neurons

extends form the sensory receptor to the CNS (brain or spinal cord) where it synapses with a secondary neuron

what is the sensory pathway for 2nd order neurons

interneuron that extends from the primary neuron to tertiary neuron or cerebellum

what is the sensory pathway for 3rd order neurons

interneuron that extends from the secondary neuron to the cerebellum (primary somatosensory cortex of parietal lobe)

*pathways to cerebellum do not have tertiary neuron

where is the upper motor neurons getting information from

in cerebral cortex, cerebral nuclei or brainstem nucleus

*direct (to lower motor neurons) or indirect pathways (interneurons then lower motor neurons)

where is ther lower motor neuron getting information from

in cranial nerve nucleus or spinal cord anterior horn or upper motor neruon

what are upper motor neurons able to do

excite or inhibit activity of lower motor neurons

what are lower motor neurons able to do

always excites skeletal muscle fibers to contract

development of neural tissue

neural plate develops neural groove

neural groove deepends as folds rise and approach one another

neural crest cells separate from neural folds

by end of 3rd week, folds meet and form neural tube surrounding neural canal

*thickening of a portion of the ectoderm (neural plate)

what is dual innervation

organ receives input from both the sympathetic and parasympathetic divisions

*have antagonistic or cooperative effects

where are sensory pathways coming from and where are they going

sensory neurons that relay sensory input from sensory receptors to the brain

where are motor pathways coming from and where are they going

series of motor neurons that relay motor output from brain to effectors

what is nearsightedness (myopia)

can see nearby objects but far objects are blurry

eyeball too long

what is farsightedness (hyperopia)

can see far objects but nearby objects are blurry

eyeball too short

what are the 4 higher order functions of the cortex of the cerebrum

intelligence and reasoning

thought, memory, and judgement

voluntary control of skeletal muscle

conscious perception of senses

what is the general process of reflex arcs

stimulus activates receptor

nerve signal is propogated through sensory neuron to the spinal cord

nerve signal is processed in the integration center by interneurons (this is a polysynaptic reflex)

nerve signal propogated by motor neuron to effector

effector responds

what is micturition

mechanism leading to urine emptying from the bladder

*mechanoreceptors detect stretching of bladder wall when urine fills the bladder, then initiate signals that are relayed along sensory neurons to the spinal cord, sensory input inhibits sympathetic output and activates parasympathetic output along motor neurons that innervate the bladder, reflec results in contraction of smooth muscle in bladder wall and relaxationg of urinary sphincters and urination occurs

what is the brachial plexus organization

*from anterior rami of C5-T1

composed in order of: roots (anterior rami), trunks, divisions, cords

what is the diencephalon

from prosencephalon

forms the thalamus, hypothalamus, and epithalamus

3rd ventricle

what is it called when there are functional differences between 2 brain hemispheres

cerebral lateralization

what does CSF fomation, circulation, reabsorption, and removal consist of

produced by choroid plexus (composed of blood capillaries, pia mater, ependymal cells) in the ventricles

CSF flows from lateral ventricles through interventricular foramen into the 3rd ventricle and then through cerebral aqueduct into 4th ventricle

CSF in 4th ventricle passes through the paired lateral apertures or the single median aperture and into the subarachnoid space as well as the central canal of the spinal cord

as CSF flows through the subarachnoid space it provides buoyancy to support the brain

CSF flows into arachnoid villi then drains into the dural venous sinuses

what are the different tastes

sweet

salt: ions

sour: acids

bitter

umami: amino acids

*water

what is the vasomotor center (what does it do with blood vessels)

controls contraction and relaxation of smooth muscle within walls of the smallest arteries to alter vessels’ diameter

what does the vasomotor center do with regulation of blood pressure in relation to the brain

both cardiac output and blood vessel diameter influence blood pressure which is controlled by the medulla oblongata

what is the realtionship between the limbic system and the prefrontal cortex

the relationship is the prefrontal cortex reasons through emoitions, manages impulse control, and conveys expressed emotions from the limbic system

what is memory in the brain

processing system of receiving, storing, and retrieving information

CN I

olfactory nerve

smell

CN II

optic nerve

vision

CN V

trigeminal

general sensory from anterior scalp, nasal cavity, nasopharynx, entire face, most of oral cavity, teeth, anterior 2/3s of tongue; part of auricle of ear; meninges

CN VII

facial

taste from anterior 2/3s of tongue

CN VIII

vestibulocholear

hearing; equilibrium

CN IX

glossopharyngeal

taste and general sensation from posterior 1/3 of tongue; general sensory from part of pharyx, visceral sensory from carotid bodies

CN X

vagus

visceral sensory information from thoracic organs and most abdominal organs

general sensory information from external acoustic meatus, tympanic membrane, part of pharynx, laryngopharynx and larynx

what is the reticular activating system

sensory component of the reticular formation responsible for altering the cerebrum to incoming sensory information

what is the structure of the reticular activating system

within the reticular formation: loosely organized gray matter of brainstem

RAS contains sensory axons that project to the cerebral cortex

what is are the 2 functions of the reticular activating system

processes visual, auditory, and touch stimuli and uses this information to keep us in a state of mental alertness

wakes us up from sleep

*highest state of consciousness is alertness

what is resting potential in neurons

there is an electrical charge difference across the plasma membrane (-70mV)

ion concentration gradients exist for K, Na, and Cl across plasma membrane

Ca concentration exists at synaptic knob

gated channels are closed

primary motor cortex (somatic motor area)

located in precentral gyrus

controls skeletal muscle activity on oppostie side of body

primary somatosensory cortex

located in postcentral gyrus

proprioreceptors, touch, pressure, pain, temperature receptors

prefrontal cortex

located rostral to premotor cortex

complex thought, judgment, personality, planning, deciding

*develops in adolescence

wernicke area

located in left hemisphere

involved in language comprehension

thalamus

information filter

focus on sound

hypothalamus

master control of autonomic nervous system

control of endocrine system

regulation of body temperature

food intake

water intake

sleep-wake rhythms

emotional behavior

pons

sensory and motor tracts are located here

medulla oblongata

rhythmicity centers: cardiovascular center and respiratory center

cerebellum

coordinates and “fine-tunes” movements

motor speech (broca) area

initiates speech motor program