Exam 4
Brain
makes of 97% of bodys nervous system in adulthood avg 1.4 kg
Nerve repair
mature neurons are incapable of cell division damage can be permanent neurons have limited capacity to repair themselves
tympanic membrane
The eardrum A structure that separates the outer ear from the middle ear and vibrates in response to sound waves.
Baroreceptor
mechanoreceptor detect pressure changes in blood vessels and in digestive, respiratory, and urinary tracts
Proprioreceptor
mechanoreceptor monitor position of joints and skeletal muscles
Tactile receptor
mechanoreceptor provides sensations of... touch (shape or texture) pressure (degree of mechanical distortion) vibration (pulsing pressure)
Perineurium
middle connective tissue layer of spinal nerves separates nerve into fascicles (axon bundles)
Facial nerves (VII)
mixed sensory (taste) and motor of face
Trigeminal nerve (V)
mixed sensory and motor of face
glossopharyngeal nerve (IX)
mixed sensory and motor of head and neck
Interneurons
most are in brain and spinal cord some ar ein autonomic ganglia located between sensory and motor neurons responsible for distribution of sensory info, coordination of motor activity involved in higher functions (memory, learning, planning)
Efferent division
motor division of PNS carries motor commands from CNS to muscles, glands, and adipose tissue
Abducens nerve (VI)
motor eye movement
oculomotor nerve (III)
motor eye movement
Accessory nerves (XI)
motor to muscles of neck and upper back
Hypoglossal nerves (XII)
motor tongue movements
Trochlear nerve (IV)
motor, eye movement
White matter
Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths. myelinated and unmyelinated axons
Type B fibers
myelenated medium diameter transmit info at intermediate speeds
Type A fibers
myelinated large diameter transmit info to and from CNS rapidly transmits critical info
Dorsal root ganglion
a nodule on a dorsal root that contains cell bodies of afferent spinal nerve neurons swelling at the dorsal root of each spinal nerve
subarachnoid space
a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid
Reflex action
near instantaneous response that does not involve the brain
Oligodendrocytes
neuroglia in CNS small cell bodies and few processes cooperate to form myelin sheath
Microglia
neuroglia in CNS smallest and least numerous neuroglia many fine branched processes migrate through nervous tissue clean cell debris, waste, pathogens
Schwann cells
neuroglia in PNS form myelin sheath or indented folds of plasma around axons- only around one axon, sometimes the whole axon Neurolemma is outer cell wall
Satellite cells
neuroglia in PNS surround ganglia regulate interstitial fluid around neurons
Two kinds of nervous system cells
neurons and neuroglia
Structural classifications of neurons
anaxonic neurons bipolar neurons unipolar neurons multipolar neurons
Two branches of spinal nerves
anterior/ventral root and posterior/dorsal root
Types of neuroglia in the CNS
astrocytes ependymal cells oligodendrocytes microglia
Unipolar neurons
axon and dendrites are fused cell body to one side make up most sensory neurons of PNS
anterior/ventral root
axons of motor neurons
posterior/dorsal root
axons of sensory neurons
Physical protection of the brain
bones of the cranium cranial meninges cerebrospinal fluid
Central nervous system organs
brain and spinal cord
Nervous system organs
brain and spinal cord receptors of sense organs nerves that connect to other systems (cranial, spinal, peripheral nerves)
Somatic sensory division
carries feedback info to somatic integration systems in CNS part of PNS and SNS neurons monitor external environment
Somatic motor division
carries info to somatic effectors (skeletal muscle) part of PNS and SNS
Motor neurons
carry instructions from CNS to peripheral effectors via efferent fibers (axons) includes somatic motor neurons of SNS, visceral motor neurons of ANS
Excitatory neurotransmitters
cause depolarization of postsynaptic membranes promote action potentials gas
Inhibitory neurotransmitters
cause hyperpolorization of postsynaptic membranes suppress action potentials brakes
Soma
cell body of a neuron contains nucleus and organelles
Phrenic nerve
cervical plexus nerve C3-C5 innervates/controls diaphragm
spinal plexuses
cervical, brachial, lumbar, sacral
Neurotransmitters
chemical messengers contained in synaptic vesicles in axon terminal of presynaptic neuron released into synaptic cleft affect receptors of postsynaptic membrane broken down by enzymes reabsorbed and reassembled by axon terminal
Carpel tunnel syndrome
compression of median nerve usually when adjacent tendons are swollen repetitive stress causes changes or loss of sensation in the areas supplied by the median nerve
Medulla oblongata
connects brain to spinal cord inferior portion has narrow central canal relays sensory info regulates autonomic functions (heart rate, BP, digestion)
Pons
connects cerebellum to brainstem sensory and motor nuclei of cranial nerves nuclei involved in respiration
Conscious or subconscious motor commands
controls skeletal muscles by traveling over three integrated motor pathways : corticospinal medial lateral
Cerebellum
coordinates repetitive body movements second largest part of brain two hemispheres covered by gray matter adjust postural muscles, program and fine tune conscious and subconscious movements
General sensory receptors
nociceptors (pain) thermoreceptors (temperature) mechanoreceptors (physical distortion) chemoreceptors (chemical concentration)
Acetylcholine
(ACh) a neurotransmitter that enables learning and memory and also triggers muscle contraction.
Ataxia
disorder of the cerebellum disturbance in muscular coordination caused by trauma or stroke, intoxication
CSF circulation order
1 Choiroid plexus 2 through ventricles to fill central canal of spinal cord (materials diffuse between the CSF and interstitial fluid of CNS across ependymal cells) 3 CSF reaches subarrachnoid space through two lateral apertures and single median aperture in roof of 4th ventricle 4 CSF flows through subarrachnoid space surrounding brain, spinal cord, and cauda equinaSp
6 Steps in process of hearing
1 Sound waves arrive at tympanic membrane 2 Movement of tympanic membrane displaces auditory ossicles 3 Movement of stapes at oval window produces pressure waves in perilymph of scala vestibuli 4 Pressure waves distort basilar membrane on their way to round window of scala tympani 5 Vibration of basilar membrane causes hair cells to vibrate against tectorial membrane 6 Information about stimulation is relayed to CNS over cochlear nerve
Coccygeal nerve pairs
1 pair
Cranial meninges layers
dura matter arachnoid matter pia matter
Thoracic nerve pairs
12 pairs T1-T12
Gross anatomy of spinal cord
18 in long, 1/2 inch wide from brain to L1 and L2
Lumbar nerve pairs
5 pairs L1-L5
Sacral nerve pairs
5 pairs S1-S5
Cervical nerve pairs
8 pairs C1-C8
Dopamine
A CNS neurotransmitter May be excitatory or inhibitory Involved in Parkinson's disease and cocaine use
Functional divisions of the PNS
Afferent division, efferent division
Blood brain barrier
BBB isolates CNS from general circulation formed by network of tight junctions regulated by astrocytes which release chemicals that control permeability of endothelium
benign paraoxysmal positional vertigo
BPPV vertigo triggered by a certain change in head position, such as tipping head up or down
Gray matter
Brain and spinal cord tissue that appears gray with the naked eye cell bodies of neurons, neuroglia and unmyelinated axons consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons
Anatomical divisions of the nervous system
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
Regions of brain
Cerebrum Cerebellum Dienchephalon Brainstem
Ventricles of brain
each cerebral hemisphere contains one large lateral ventricle third ventricle is in diencephalon which communicates with each lateral ventricle fourth ventricle extends into medulla oblongata and joins central canal of spinal cord
Action potential
electrical impulse on a plasma membrane via ion movement produced by graded potential propagates along surface of axon to synapse Na+ and K+ are primary determinants of membrane potential Na+ and K+ channels are either active or passive
Gyri
elevated ridges of the brain
Three connective tissue layers of spinal nerves
epineurium, perineurium, endoneurium
Neurons
excitable cells that initiate and conduct impulses that make possible all nervous system functions intercellular communication basic functional units of nervous system send and receive signals function in communication, info processing, and control
Referred pain
feeling pain in an uninjured part of the body when pain originates in another location visceral pain can manifest as pain in body surface e.g. heart attack in left arm
Myelin
formed by oligodendrocytes, shchwann cells insulates myelinated axons increases speed of action potential makes nerve appear white because of fat
Neuroglia
glial cells essential to survival and functions of neurons preserve functions of nervous tissue many types in PNS and CNS make up half the volume of the nervous system
Multipolar neurons
have one long axon and two or more dendrites common in the CNS all motor neurons that control skeletal muscles
CSF circulation
From choroid plexus (where its produced) Through ventricles To central canal of spinal cord Into subarachnoid space via two lateral apertures and one median aperture around the brain, spinal cord, and cauda equina
Gamma-aminobutyric acid (GABA)
Inhibitory effectFunctions in CNS are not well understood
Spinal cord
housed within protective membrane (meninges) and vertebral column carries sensory and motor info between brain and body gives rise to spinal nerves
Peripheral nervous system (PNS)
includes all neural tissue outside the CNS delivers sensory info to CNS carries motor command to tissues
Vagus nerves (X)
Mixed (sensory and motor), widely distributed in the thorax and abdomen
Endoneurium
innermost connective tissue layer of spinal nerves surrounds individual axons
Types of neuroglia in the PNS
insulate neuronal cell bodies and most axons satellite cells schwann cells
Diencephalon
integrates sensory info with motor commands made of thalamus, hypothalamus, epithalamus
Seratonin
NS neurotransmitter Affects attention and emotional states
Ependymal cells
Neuroglia in CNS form epithelium that lines central canal of spinal cord and ventricles of brain produce and process cerebrospinal fluid have cilia that help circulate CSF
Astrocytes
Neuroglia in CNS large cell bodies with many processes function to maintain blood brain barrier create 3D framework for CNS repair damaged nervous system guide neuron development control interstitial environment
Special senses
Olfaction (smell) Gustation (taste) Vision Equilibrium (balance) Hearing
Parasympathetic ANS responses
Pupil constriction Saliva production increased Blood vessel constriction Heart rate decreased Bronchial muscle contracted Digestion increased Increased urine secretion
Sympathetic ANS responses
Pupil dilation Saliva production reduced Blood vessel dilation Heart rate increased Bronchial muscle relaxed Digestion decreased Decreased urine secretion
Babinski reflex
Reflex in which a newborn fans out the toes when the sole of the foot is touched occurs without descending inhibition
Cholinergic synapses
Release acetylcholine (ACh) at All neuromuscular junctions involving skeletal muscle fibers Many synapses in CNS All neuron-to-neuron synapses in PNS All neuromuscular and neuroglandular junctions in parasympathetic division of ANS
Norepinephrine
Released by adrenergic synapses Excitatory and depolarizing effect Widely distributed in brain and portions of ANS
Cerebrum
largest part of brain controls all conscious thoughts and intellectual function processes somatic and sensory info divided into left and right hemispheres
Pia matter
layer of cranial meninges attached to brain surface by astrocytes
Arachniod matter
layer of the cranial meninges attaches to dura matter covers brain
autonomic nervous system
operates without conscious instruction coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions regulate heartbeat, smooth muscle contraction, gland secretions for homeostasis 2 divisions: sympathetic and parasympathetic divisions
Epineurium
outermost connective tissue layer of spinal nerves network of collagen fibers
Dura matter
outermost layer of the cranial meninges surrounding the brain and spinal cord fused to periosteum
Cranial nerves
part of PNS connect to brain 12 pairs connected to brain
Autonomic nervous system (ANS)
part of PNS involuntary response to physiological functions
Parasympathetic division
part of PNS and ANS coordinates the bodys normal resting activities sometimes called the "rest and repair" division or "rest and digest" conserve energy maintain metabolic rate
Enteric nervous system
part of PNS and ANS millions of neurons in digestive tract intiates and coordinates visceral reflexes without CNS
Sympathetic division
part of PNS and ANS prepares the body to deal with immediate threats/emergencies to the internal environment produces fight or flight response increase alertness, metabolic rate, muscular abiltiy
Epithalamus
part of diencephalon pineal gland
Thalamus
part of diencephalon relays and processes sensory info regulation of consciousness, sleep, and alertness
Hypothalamus
part of diencephalon secretes ADH and ocytocin regulates circadian rythm produces emotion and behavioral drives (hunger, thirst, food intake) has pituitary gland
Spinal nerves
part of pns attach to spinal cord all spinal nerves are mixed nerves
Midbrain
processes sight, sound, and associated reflexes maintains consciousness
Brainstem
relays info between spinal cord and cerebrum or cerebellum made of midbrain, pons, and medulla oblongata
Afferent division
sensory division of PNS carries sensory info from receptors in peripheral tissues to CNS
Olfactory nerves (I)
sensory function (smell)
Optic nerves (II)
sensory function (vision)
basilar membrane of cochlea
separates the cochlear duct from the scala tympani
Coccygeal plexus
serves a small region over the coccyx
Lumbar plexus
serves the back, abdomen, groin, thighs, knees, and calves
Brachial plexus
serves the chest shoulders arms and hands
Cervical plexus
serves the head beck and shoulders
Sacral plexus
serves the pelvis, buttocks, genitals, thighs, calves, and feet
Sulci
shallow grooves that separate gyri
Dendrites
short and highly branched processes extending from soma of neuron neurons have one or more dendrites conduct nerve signals to the cell body of the neuron distal ends of dendrites of sensory neurons are receptors
Axon
single, long cytoplasmic process propogates electrical signals (action potentials) sometimes covered by a fatty myelin sheath conducts impulses away from soma
Anaxonic neurons
small all cell processes look similar found in brain and special sense organs
Bipolar neurons
small and rare one dendrite and one axon found in special sense organs
Neuron structures
soma axon dendrite
Olfaction
special sense sense of smell olfactory organs location in nasal cavity
Gustation
special sense taste primary location taste buds in mouth
Synapse
specialized site where a neuron communicates with another cell includes a presynaptic (sending) and postsynaptic (receiving) neuron synaptic cleft is space between neurons electric and chemical types of synapses
Dermatome
specific bilateral area of skin supplied by a single pair of spinal nerves
Equilibrium
state of physical balance sensation provided by receptors of vestibular complex
Central nervous system functions
structural and functional center of entire nervous system integrates sensory info, evaluates it, and initiates an outgoing response process and coordinate sensory data from inside and outside body motor control commands intelligence, memory, learning, emotion
Nervous system can be divided by
structure flow of information control of effectors innervation
Cerebrospinal fluid (CSF)
surrounds all exposed surfaces of CNS supports brain, cushions neural structures, transport nutrients, chemical messengers, waste produced by choroid plexus*
Primary taste sensations
sweet, salty, sour, bitter
Types of mechanoreceptors
tactile receptors, baroreceptors, proprioceptors
General senses
temperature, pain, touch, pressure, vibration, proprioception (body position)
cochlear nerve
the branch of the auditory nerve that transmits auditory information from the cochlea to the brain
Optic nerve
the nerve that carries neural impulses from the eye to the brain processes all info from eyes to the brain
Neurolemma
the outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron forms the outermost layer of the nerve fiber in the peripheral nervous system.
Number of spinal nerves
thirty one pairs
auditory ossicles
three small bones linked together that connect the eardrum to the inner ear malleus (hammer), incus (anvil), stapes (stirrup)
Type C fibers
uhnmyelinated small diameter transmit info slowly
Sensory neurons
unipolar cell bodies grouped in sensory ganglia processes (afferent fibers) extend from sensory receptors to CNS includes somatic sensory neurons and visceral sensory neurons
vestibulochochlear nerve (VIII)
vestibular nerve = balance and equilibrium cochlear nerve = hearing
Shingles
viral disease that affects the peripheral nerves and causes blisters on the skin that follow the course of the affected nerves occur along dermatomes
Meningitis
viral or bacterial infection of meninges
Somatic nervous system (SNS)
voluntary control of information from brain to organs
lumbosacral enlargement
wider area of spinal cord with more gray matter innervates pelvis and lower limbs
Cervical enlargement
wider area of spinal cord with more gray matter supplies nerves to the shoulder and upper limbs