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)

Arachnoid mater

middle membrane of spinal meninges

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

Spinal meninges

dura mater, arachnoid mater, pia mater protect spinal cord, carry blood supply

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

Pia mater

innermost membrane of spinal meninges

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

Dura mater

outermost membrane of spinal meninges

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