Bio 201 Exam 5

Front 1

Subdivisions of the Nervous System

Back 1

- Central Nervous System
- Peripheral Nervous System

Front 2

Central Nervous System (CNS)

Back 2

- Brain & Spinal Cord enclosed in bone

- Nucleus (nuclei):
-- Cluster of neuronal cell bodies found in the CNS

Front 3

Peripheral nervous System (PNS)

Back 3

- Nerves and ganglia not in CNS
- nerve: bundle of nerve fibers in connective tissue
- Ganglion (ganglia):
-- Cluster of neuronal cell bodies found outside CNS

Front 4

Functional Divisions of PNS

Back 4

- Sensory (Afferent) divisions: receptors signal to CNS
-- Visceral and Somatic sensory divisions
- Motor (Efferent) division: CNS signals to effectors
-- Visceral Motor aka Autonomic Nervous System (ANS)
-- Somatic motor division effectors: skeletal muscles

Front 5

Visceral Motor Division (Autonomic Nervous System)

Back 5

- Sympathetic Division: Fight or flight system
- Parasympathetic divisions: Rest & Relax system

Front 6

Central Nervous System: Consists of . . .

Back 6

- Brain and Spinal Cord

Front 7

Definitions: Ipsilateral
Contralateral
Decussation
Commissure

Back 7

- Same side of the body
- Opposite side of the body
- Crossing of fibers from one side of the CNS to the other
- Anatomical site where fibers decussate (intersection)

Front 8

Definitions:
- Caudal
- Rostral

Back 8

- Caudal: Toward the head
- Rostral: Toward the tail

Front 9

Parts of the: Hindbrain

Back 9

- Pons
- Medulla oblongata
- Cerebellum

Front 10

Parts of the: Midbrain

Back 10

- Superior colliculus
- Inferior colliculus

Front 11

Parts of the: Forebrain

Back 11

- Diencephalon: -- Hypothalamus -- Thalamus
- Cerebrum: -- Basal Ganglia -- Cerebral Cortex

Front 12

Anatomy of the Forebrain

Back 12

- Longitudinal Fissure separates cerebral hemispheres
-- Gyrus: raised folds -- Sulcus: grooves between gyri
- Cerebral Cortex: Surface layer of gray matter
- Nuclei: Deeper masses of Gray Matter (Cell's Bodies)
- White Matter: bundles of axons (tracts)

Front 13

During Embryonic Development, what tissue develops into Nervous System?

Back 13

- The Nervous System develops from Ectoderm
-- By 4th week, neural tube exhibits 3 anterior dilations which become forebrain, midbrain and hindbrain

Front 14

What Protects the CNS?

Back 14

- Bone: Skull, vertebral column
- Meninges: Dura mater, Arachnoid, Pia mater
- Cerebrospinal Fluid (CSF)
- Blood-brain barrier

Front 15

Anatomy of the Meninges

Back 15

- Dura mater: tough inner & outer layers w/dural sinuses which empty into the internal jugular veins
- Arachnoid: highly vascular
- Subarachnoid space: contains CSF
- Pia mater: gentle vascular layer supplies blood to brain

Front 16

Define: Meningitis

Back 16

- Inflammation of the meninges

Front 17

Ventricles: Internal chambers (in the CNS) filled with CSF and lined with epenymal cells creating a blood-brain barrier

Back 17

- Lateral V. found in cerebral hemispheres
- 3rd V. under corpus collosum near hypo/thalamus
- Cereral aqueduct: runs through midbrain 3rd to 4th V.
- 4th V. between pons & cerebellum
- Central canal runs through spinal cord

Front 18

Cerebrospinal Fluid (CSF): the clear liquid that fills ventricles and canals, bathing brain's external surface in the subarachnoid space

Back 18

- Produced by choroid plexus: specialized ependymal cells in 3rd & 4th Ventricles
- Escapes from 4th V. to surround the brain
- Reabsorbed by arachnoid villus into dural sinuses
- Brain produces and absorbs ~500ml per day

Front 19

Flow of Cerebrospinal Fluid (CSF) Steps 1 - 4

Back 19

1. Secreted by choroid plexus in lateral ventricle
2. Flows through interventricular foramina into 3rd V.
3. Choroid plexus in 3rd V. adds more CSF.
4. CSF flows down cerebral aqueduct to 4th Ventricle

Front 20

Flow of Cerebrospinal Fluid (CSF) Steps 5 - 8

Back 20

5. Choroid plexus in 4th Ventricle adds more CSF
6. CSF flows out two lateral and one median apertures
7. CSF fills subarachnoid space, bathes external brain surfaces and spinal cord - 8. CSF resorbed at arachnoid villi into venous blood of dural venous sinuses

Front 21

Functions of Cerebrospinal Fluid

Back 21

- Buoyancy: neutrally buoyant brain won't damage self
- Protection: cushions brain from hitting skull walls
- Chemical stability: rinses away wastes

Front 22

Blood-Brain Barrier

Back 22

- Limits exchange between nervous tissue and blood
- Brain Capillaries: astrocytes connect w/ tight junctions
- O2, CO2, alcohol, steroid hormones & H2O pass through membrane
- Everything else is selectively transported by carriers

Front 23

Blood Supply to Brain

Back 23

- Brain needs lots of blood, O2, & glucose
-- consumes 20% of body's glucose
- Brain cells are extremely susceptible to hypoxia
-- No stored O2, no energy reserves
- 4 min without blood = permanent brain cell injury

Front 24

Parts & Functions of Brain Stem: Hindbrain & Midbrain

Back 24

- Respiration, circulation, digestion
- Medulla
- Pons
- Cerebellum (movement)
- Midbrain: aka mesencephalon

Front 25

Hindbrain: Reticular Activating System

Back 25

- Clusters of gray matter (nuclei) scattered throughout pons, midbrain, & medulla: Reticular formation
- Arouses Cerebral cortex, regulates sleep & conscious attention - cardiac & vasomotor centers
- Origin of descending analgesic pathways (pain control)

Front 26

Brain Waves and Sleep: EEG correlates to states of consciousness

Back 26

- Sleep is temporary state of unconsciousness
- Coma is unconsciousness with no possible arousal
- Reticular formation: regulates alertness
- Circadian rhythm set by suprachiasmatic nucleus in hypothalamus

Front 27

Sleep: Reticular Activating System

Back 27

- Globally activate cerebral cortex
- Lower brain stem

Front 28

Cerebellum

Back 28

- Arbor Vitae
- Gray matter
- Connected to brainstem by cerebellar peduncles
-- fiber tracts
- Sits atop the 4th Ventricle

Front 29

Why is the Cerebellum Important?

Back 29

- Balance
- Eye movement (vestibulocerebellum)
- Timing/coord of voluntary movement (spinocerebellum)
- Planning and initiation of voluntary movement (cerebrocerebellum)

Front 30

Midbrain: aka Mesencephalon

Back 30

- Cerebral aquaduct
- CN III and IV exit: Eye movement
- Substantial nigra (part of basal ganglia) degeneration leads to tremors and Parkinsons disease
- Red nucleus: part of motor system

Front 31

Midbrain: Tectum

Back 31

- Superior colliculus tracks movement, ocular reflexes
- Inferior colliculus auditory reflex turns head to sound
- Collectively referred to as the tectum (tectospinal tract)

Front 32

Forebrain: Diencephalon: Thalamus

Back 32

- Relays and integrates sensory information from body to cerebral cortex and basal ganglia
-- Spotlight of attention

Front 33

Forebrain: Diencephalon: Hypothalamus

Back 33

- Coordinates functions of the Autonomic Nervous Sys.
-- emotional expression
- Regulates: Body Temperature, Thirst & Urine output, Food intake, production/control of pituitary hormones
- Circadian rhythms: (suprachiasmatic nucleus)

Front 34

Forebrain: Diencephalon: Pineal Gland

Back 34

- Secretes melatonin and seratonin
-- Released primarily during darkness in response to light/dark cues from eyes
-- Entrains body's circadian rhythms with external light/dark cycles

Front 35

Forebrain: Basal Ganglia

Back 35

- Scattered deep brain nuclei
-- located between cerebral cortex & thalamus
-- also in midbrain & near thalamus
- Helps refine movement signal from cerebral cortex by inhibiting "incorrect" motor activity: "brake" hypothesis

Front 36

Brake Hypothesis Works by Disinhibition

Back 36

- Release from/inhibit ongoing inhibition
- The system wants to be on, but is kept turned off by constant inhibitory signals
- to activate the system, it simply stops the inhibition

Front 37

Forebrain: Damage to Basal Ganglia

Back 37

- Huntington's chorea
- Parkinson's disease
- Schizophrenia, depression, obsessive compulsive disorder, others. . .

Front 38

Huntington's Chorea ("dance")

Back 38

- Causes:
-- Genetic overproduction of protein Huntingtin
-- Toxic destruction of cells in basal ganglia damages basal ganglia's ongoing inhibition of movements
- Major symptom: Uncontrolled movements

Front 39

Parkinson's Disease: Caused by degeneration of dopaminergic cells of substantia nigra

Back 39

- Major symptoms:
-- resting tremor
-- slow movement (bradykinesia) & rigidity
- Basal Ganglia no longer perform task of reinforcing the desired movement of inhibiting "wrong" ones

Front 40

What is the Basal Ganglia's Function?

Back 40

- It is more involved in preventing movements than in causing or allowing them
- It works by disinhibition
- It is active unless purposefully inhibited

Front 41

Forebrain: Limbic System

Back 41

- Loop of cortical structures surrounding deep brain
-- Amygdala, hippocampus, fornix & cingulate gyrus
- Amygdala important in emotions, esp. negative ones
- Hippocampus important in memory
- Functions of other components are unclear "Mood"?

Front 42

Hippocampus: the Sea Horse

Back 42

- Important in organizing sensory & cognitive information into a memory (declarative memory)
- Lesion to it causes inability to form new memories
- Larger in people with better memories (Size changes with use)

Front 43

Memory: Information management requiring learning, memory and forgetting

Back 43

- Anterograde Amnesia cannot store new memory
- Retrograde Amnesia cannot remember old data
- Distributed throughout brain
- 4 Different Types of Memory

Front 44

Different Types of Memory

Back 44

- Declarative (facts) -- Long-term: Hippocampus
- Procedural (motor learning): Cerebellum
- Short-term (working memory): Prefrontal Cortex
- Emotional (aversive learning): Amygdala

Front 45

Emotion: A Feeling Plus Motivation

Back 45

- Prefrontal Cortex controls emotional expression
- Emotions form in hypothalamus & amygdala
-- Artificial stimulation can produce emotions
- Much of our behavior is learned by rewards and punishments or responses others to them

Front 46

Forebrain: Cerebral Cortex

Back 46

- Gray Matter: Cells (neurons) - 3mm thick
- Neocortex: 6-layered tissue, each layer varied in cell shape and density and layer thickness
- White Matter: Axons

Front 47

Forebrain: Four Lobes of Cerebrum (Named for Bones They Sit Under

Back 47

- Occipital Lobe
- Temporal Lobe
- Frontal Lobe
- Parietal Lobe
- Insula: emotional aspects of pain

Front 48

Forebrain: Cerebrum - Gross Anatomy

Back 48

- Precentral gyrus
- Postcentral gyrus
- Central Sulcus
- Lateral Sulcus
- Occipital, Temporal, Parietal, Frontal lobes

Front 49

Functional Areas of the Brain: Primary vs. Association

Back 49

- Primary: 1st part of Cerebral cortex to receive sensory information &/or send motor information
- Assoc: where integration of sensory & motor info occurs
- Cognition: Awareness, perception, thinking, knowledge, & memory

Front 50

Brain Lesions: Strokes, Accidents or other injuries lead to knowledge about the regional functions

Back 50

- Parietal Lobe: contralateral neglect syndrome
- Temporal lobe: Prosop- / -agnosia inability to recognize faces/objects
- Prefrontal lobe: problems with personality & decision making, inability to plan and execute appropriately

Front 51

Lobotomy of Phineas Gage: Prefrontal Cortex

Back 51

- Planning
- Moral Judgment
- Emotional Control
- Damage = perseveration

Front 52

Forebrain: Overview of Primary Functional Areas

Back 52

- Primary Visual: Occipital lobe receives visual info
- Auditory: Temporal lobe receives info from cochlea
- Somatosensory: Parietal lobe Postcentral Gyrus receives touch/texture info from skin
- Motor: Frontal lobe, precentral gyrus sends to skeletals

Front 53

Forebrain: Overview of Association Areas - Somesthetic

Back 53

- Parietal Lobe
-- Limb position (proprioception)
-- Location of touch or pain
-- Shape, weight & texture of an object

Front 54

Forebrain: Overview of Association Areas - Visual

Back 54

- Occipital Lobe
-- Identify the things we see
-- Faces are recognized in Temporal lobe

Front 55

Forebrain: Overview of Association Areas - Auditory

Back 55

- Temporal Lobe
-- Remember the name of a piece of music
-- Identify a person by his voice

Front 56

Forebrain: Overview of Association Areas - Motor

Back 56

- Frontal Lobe
-- More commonly called the Premotor area

Front 57

Somesthetic/Somatosensory Sensation

Back 57

- Sense of touch
- Primary somatosensory area is in the postcentral gyrus
- Left side senses right side of body (decussation in medulla)

Front 58

Sensory Homunculus: "Little Man"

Back 58

- A visual representation of which portion of ht e cerebral cortex recieves information form each body region
- More sensitive regions take up more space
- Proportional to the number of receptors

Front 59

Motor Control: Intention to contract a muscle begins in motor association area (premotor area) of frontal lobes

Back 59

- Primary Motor Cortex in precentral gyrus processes motor control program from premotor area
- Sends signal to motor neurons in spinal cord
- Supply muscles of contralateral side due to pyramidal decussation

Front 60

Motor Homunculus

Back 60

- Proportional to number of muscle motor units in a region
- Areas with finer motor control are represented by larger areas of cortex (face & hands)

Front 61

Language Areas of the Brain: Wernicke's Area

Back 61

- Recognition of spoken & written
- Creates plan of speech (Left hemisphere)
- Angular gyrus processes text into spoken form

Front 62

Language Areas of the Brain: Broca's Area

Back 62

- Generates motor program for larynx, tongue, & lips
-- "Premotor" area for language
- Transmits that program to primary motor cortex for action (Left hemisphere for 95%)

Front 63

Language Areas of the Brain: Affective Language Area

Back 63

- Lesions produce aprosodia: emotionless speech
- Same area as Broca's on opposite hemisphere

Front 64

Aphasia: Any Language Deficit

Back 64

- Broca's=Nonfluent aphasia: slow speech, difficulty choosing words. - Wernicke's=Fluent aphasia: normal/excessive speech makes little sense. - Anomic aphasia: speech & understanding normal, but text & pictures make little sense

Front 65

Plasticity

Back 65

- Ability of cortex to remap functions in response to experience
- Brain not completely determined by genetics
- Remodeling of somatosensory map after loss of parts
- Growth of hippocampus in those who memorize a lot

Front 66

Habituation

Back 66

- Decreased responsiveness to repetitive stimulation
- Close Ca++ channels on presynaptic neuron
-- smaller EPSP

Front 67

Sensitization

Back 67

- Increased responsiveness to stimuli
- Serotonin released from interneuron
- Increased length of AP
- Larger EPSP

Front 68

Cranial Nerves

Back 68

- 12 Pairs arise from the brain
- Part of PNS not CNS
- Input and output remains ipsilateral except CN 2 & 4

Front 69

Motor Homunculus

Back 69

- Proportional to number of muscle motor units in a region
- Areas with finer motor control are represented by larger areas of cortex

Front 70

Language: Wernicke's Area

Back 70

- Permits recognition of spoken and written language
- Creates a plan of speech
- Only in left hemisphere
- Angular Gyrus processes text into a form we can speak

Front 71

Language: Broca's Area

Back 71

- Generates motor program for larynx, tongue, & lips
-- Premotor area for language
- Transmits that program to primary motor cortex for action
- Left hemisphere for most people

Front 72

Language: Affective Language Area Lesions

Back 72

- Produce Aprosodia
-- Emotionless Speech
- Same area as Broca's area on opposite hemisphere

Front 73

Cranial Nerves

Back 73

* I Olfactory - VI Abducens - XI Accessory
* II Optic * VII Facial - XII Hypoglossal
- III Oculomotor - VIII Vestibulocochlear
- IV Trochlear - IX Glossopharyngeal
* V Trigeminal * X Vagus

Front 74

Olfactory Nerve (I)

Back 74

- Provides sense of smell
- Provides way to bypass the blood-brain barrier

Front 75

Optic Nerve (II)

Back 75

- Carries visual information from eyes to brain

Front 76

Trigeminal Nerve (V)

Back 76

- Main sensory nerve from face
-- Touch, Pain, Temperature
- Major motor nerve to muscles of mastication

Front 77

Facial Nerve (VII)

Back 77

- Main motor nerve to muscles of the face
- Provides facial expressions
- Sense of taste on anterior 2/3s of tongue
- Innervates salivary, tear, nasal, & palatine glands

Front 78

Vagus Nerve (X)

Back 78

- Major parasympathetic motor (& accessory) pathway
-- Regulation of viscera
- Provides swallowing, speech

Front 79

Anatomy of Spinal Cord

Back 79

- Cylinder of nerve tissue within vertebral canal
- 31 pairs of nerves divided into 4 regions:
-- Cervical, Thoracic, Lumbar, Sacral
- Cervical (C4 - T1) and Lumbar (T9 - T12) Enlargements
- Cauda equinae after L1

Front 80

Functions of the spinal cord

Back 80

- Conduction: passing info up and down the cord
- Reflexes: involuntary, stereotyped responses to stimuli
-- Involves Brain, spinal cord & Peripheral nerves
- Central Pattern Generators control flexors & extensors
- Locomotion: repetitive, coordinated action of muscles

Front 81

Spinal Nerves

Back 81

- Receive sensory information
- Send motor information

Front 82

Dermatomes

Back 82

- Portion of body innervated by a particular spinal nerve
- Overlap at edges by 50% so Anesthesia requires 3 successive spinal nerves

Front 83

Meninges of the spinal cord

Back 83

- 3 fibrous layers enclosing Spinal Cord
- Dura Mater
- Arachnoid
- Pia Mater

Front 84

Cross-Sectional Anatomy of the Spinal Cord

Back 84

- Gray Matter: neuron cell bodies with little myelin
-- Separated into dorsal, ventral, and lateral horns
- White Matter: myelinated axons
- Central Canal: continuous with 4th ventricle
-- Contains CSF

Front 85

Gray Matter in Spinal Cord

Back 85

- Dorsal Horns: where afferent neurons terminate
-- Dorsal root of spinal nerve is axons of sensory fibers
- Ventral horns: cells of efferent somatic motor fibers
-- Ventral root is axons of motor fibers
- Lateral horns: cells of efferent autonomic NS fibers

Front 86

Spinal White Matter

Back 86

- Bundles of myelinated axons that carry signals
-- Some ascending, some descending

Front 87

Spinal White Matter: Dorsal Columns

Back 87

- Ascending pathway: carries touch, vibration, some proprioception
- Decussation of 2nd order neuron in medulla
- 3rd order neuron in Thalamus carries signal to primary somatosensory cortex

Front 88

Spinal White Matter: Spinothalamic Tract

Back 88

- Ascending pathway: carries pain, pressure, temperature, tickle & itch
- Decussation of 2nd order neuron in spinal cord at or near where it entered the cord
-- not in the brainstem

Front 89

Spinal White Matter: Spinocerebellar Tract

Back 89

- Ascending: carries proprioceptive signals to cerebellum
- Uncrossed

Front 90

Spinal White Matter: Corticospinal Tract

Back 90

- Descending from primary motor cortex
- Carries motor control info to vertebral horn then skeletal muscles
- Allows precise coordinated movement
- Decussation in medulla

Front 91

Spinal White Matter: Other Descending Motor Tracts

Back 91

- Tectospinal tract: reflex movements of head based on eye and ear movement
- Reticulospinal tract: controls limb movements to maintain posture. - Descending analgesic pathways
- Vestibulospinal tract: postural activity responds to ears

Front 92

Reflexes: Quick, Involuntary, Stereotyped reactions of glands or muscle to sensory stimulation

Back 92

- Quick because of myelinated axons
- Few neurons = little synaptic delay

Front 93

Types of Reflexes

Back 93

- Visceral: organs are effectors
- Somatic Reflexes: Skeletal muscles are effectors
- Conditioned Reflexes (not really): feed forward responses
-- Unconscious reactions requiring forebrain

Front 94

Stretch Reflex

Back 94

- When a muscle is stretched, it contracts

Front 95

Flexor Withdrawal Reflexes

Back 95

- Spinal polysynaptic reflex arc

Front 96

Crossed Extensor Reflex

Back 96

- Shifts weight off of stimulated leg
- Extends opposite leg
- Contracts stimulated leg
- Acts via excitatory and inhibitory interneurons in cord

Front 97

Central Pattern Generators

Back 97

- Uses same neural circuitry as crossed extensor reflexes
- Extends opposite leg
- Contracts stimulated leg