A&P Chp. 12:The Central Nervous System

Question 1

Gray Matter

Answer 1

mostly unmyelinated processes and neuron cell bodies

Question 2

White Matter

Answer 2

myelinated fiber tracts (axons)

Question 3

Major Subdivisions of the Brain

Answer 3

Cerebral Hemispheres
Diencephalon: thalamus, hypothalamus, epithalamus
Brain Stem: midbrain, pons, medulla oblongata
Cerebellum “little brain”

Question 4

Does size represent intelligence?

Answer 4

No. Size and number of neurons is irrelevant to intelligence. Complexity, or interactions of neurons and how they work together, dictate processing power.

Question 5

Brain Ventricles

Answer 5

Made of epidymal cells
Fluid filled spaces in the brain
2 Lateral Ventricles: C-shaped chambers deep in the brain where most of the cerebrospinal fluid is made and connected to a 3rd ventricle
3rd ventricle: slit between the right and left halves of the thalamus; connects to 4th
4th ventricle: lies between brain stem and cerebellum; connects to central canal of spinal cord; CSF then exits and goes around entire brain and spinal cord

Question 6

Gyrus

Answer 6

elevated ridges of brain
Precentral gyrus: controls skeletal muscle
Postcentral gyrus: locates where senses are coming from

Question 7

Sulcus (sulci)

Answer 7

Shallow grooves of brain
Central Sulcus: separates frontal from parietal lobe; in between precentral and postcentral gyrus
Lateral Sulcus: separates from from temporal lobe; very deep but not a fissure
Parieto-occipital Sulcus: separates parietal from occipital lobe

Question 8

Fissure(s)

Answer 8

Deep grooves that separate major regions
Longitudinal Fissure: Separates R and L hemispheres
Transverse Fissure: Separates cortex from cerebellum

Question 9

Cerebral Lobes/5 Hemispheres

Answer 9

1. Frontal
2. Parietal
3. Temporal
4. Occipital
5. Insula

Question 10

Insula

Answer 10

Cerebral Lobe/Hemisphere hidden deep to portions of the temporal, parietal, and frontal lobes

Question 11

Cerebral Cortex

Answer 11

Center of consciousness (knowledge, memories, everything)
Contains neuron cell bodies, dendrites, unmylinated axons, and glial cells (nuclei)
A rich capillary blood supply is near for high metabolic rate
Folds greatly increase surface area possibly meaning greater intelligence
Three types of activity areas: motor, sensory, association
Consciousness involves all areas of the brain

Question 12

Primary Motor Cortex

Answer 12

Motor Area of the Cerebral Cortex
Precentral gyrus of frontal lobe
Primarily involved in voluntary motor control area devoted to skilled muscles (controls fingers, face, etc)
Controls skeletal muscles

Question 13

Map of the Primary Motor Cortex

Answer 13

Motor Homunculus: shows the locations on the precentral gyrus which control the skeletal muscles of each body region.
More precise movements require more neurons which is why fingers and face take up more room than arms and legs which have broad movements.
Control is contralateral: affecting the opposite side

Question 14

Premotor Cortex

Answer 14

Motor Area of the Cerebral Cortex
Anterior to the primary motor cortex
Involved in learned repetitious or patterned movements such as learning the piano
Does not control skeletal muscles
If damaged, you can learn again
Trained brain to do these actions

Question 15

Damage to Primary Motor Cortex

Answer 15

Contralateral: affecting opposite side of the body
Only voluntary control of skeletal muscle is lost and it can never be regained. It is impossible to relearn.
Reflexes remain because they are controlled by the spinal cord.

Question 16

Damage to Premotor Cortex

Answer 16

Loss of programmed motor skills
Can be relearned if brain is trained again
Muslce strength and the ability to perform tasks remain (not automatic tasks)

Question 17

Language Areas

Answer 17

Motor Area of the Cerebal Cortex
A motor center fro speech, controlling muscles of the tongue, throat, and lips
involved in planning some voluntary motor activities
Only found in one hemisphere….left?

Question 18

Frontal Eye Field

Answer 18

Motor Area of the Cerebral Cortex

Controls voluntary movements of the eye

Question 19

Primary Somatosensory Cortex

Answer 19

Sensory area of the cerebral cortex
Pencil Poking demonstration: can’t read braille with your shoulder becasue receptive field of neurons is bigger
Receives inputs directly from peripheral somatic sensory receptors
Localizes points of the body where sensations originate
Distribution of input areas for cutaneous sensations
Spaital Discrimination: identifies the areas of the body being stimulated

Question 20

Somatosensory Association Area

Answer 20

Sensory Area of the Cerebral Cortex
Identify key in your hand by senses associated with what a key looks like.
Posterior to the primary somatosensory area
Integrates and analyzes information relative to size, texture for identification
Gets input from primary somatosensory association area

Question 21

Visual Cortex

Answer 21

Sensory Area of the Cerebral Cortex
Medial surface of occipital lobe
Impulses from teh eyes are routed through the thalamus
Optical Illusions
Sensory fibers cross over to the opopsite side at the optic chiasm; matters what you are looking at and where it is located
Lateral geniculate nucleus (visual area) of the thalamus

Question 22

Auditory Cortex

Answer 22

Sensory Area of the Cerebral Cortex
Superior part of the temporal lobe
Primary auditory cortex: pitch rhythm and loudness
Auditory association area: identifies/ perceives sounds using memories as references

Question 23

Olfactory Cortex

Answer 23

Sensory Area of the Cerebral Cortex
Located above the orbits in the medial portion of the temporal lobes
Conscious awareness of different smells

Question 24

Anterior Association Area

Answer 24

Multimodal Association Area
Prefrontal cortex
matures slowly (doesn’t finish til 20s) and influenced by environment
anterior frontal lobe
intellect, complex learning, recall and personality
Judgment and planning

Question 25

Posterior Association Area

Answer 25

Multimodal Association Area temporal, parietal, and occipital lobes pattern recognition, localizing position receives input from motor and other sensory association areas and interprets it Ex: dropping an acid bottle, many sensory inputs together give the dominant feeling of danger

Question 26

Frontal Lobotomy

Answer 26

Sever the frontal lobe from the rest of the brain Stops all strong emotional reaction "Shutter Island"

Question 27

Limbic Association Area

Answer 27

Multimodal Association Area Cingulate and parahippocampal gyri, and hippocampus Provides emotional impact and sense of danger

Question 28

Brain Lateralization

Answer 28

Both hemispheres participate in every activity, but one hemisphere is dominant for most activites Left Hemisphere: language skills, math and logic Right Hemisphere: creative skills, intuition, emotion, appreciateion of art and music, visual-spatial skills Most right dominant are left handed and male Most left dominant are right handed Equal function may result in ambidexterity and/or dyslexia

Question 29

Commissural Fibers

Answer 29

Myelinated fibers providing type of connection within the CNS connects the R and L hemispheres Ex: corpus callosum "body collosal"

Question 30

Association Fibers

Answer 30

Myelinated fibers providing type of connection within the CNS connect neurons within one hemisphere

Question 31

Projection Fibers

Answer 31

Myelinated fibers providing type of connection within the CNS connect cerebral hemispheres to other parts of the CNS Ex: Internal capsule

Question 32

Cerebral White Matter

Answer 32

Myelinated fibers providing the 3 types of connection within the CNS

Question 33

Deep Cerebral Gray Matter (Basal Nuclei)

Answer 33

Diffuses masses of gray matter deep within the cerebral hemispheres Involved in regulating slow, sustained motor movements such as arm swinging Also inhibit unnecessary movements (stabalize and smooth primary movements) This area is affected in Parkinson's Disease causing tremors and slow, unsteady movements

Question 34

Diencephalon

Answer 34

Brain region composed of thalamus, hypothalamus, and epithalamus Surrounded by the cerebral hemispheres Encloses the third ventricle

Question 35

Thalamus

Answer 35

"Gateway to the Cortex" Egg shaped collection of nuclei found in the Diencephalon Serves as a major switching station as impulses transfer from one neuron to the next Forms the lateral walls of the third ventricle Receives input from all ascending pathways and afferent impulses from all senses except smell Processes sensory information: crude recognition of sensation (cerebral processing required for precise localization and conscious awareness)

Question 36

Hypothalamus

Answer 36

Found below Thalamus in the Diencephalon Forms the bottom of the third ventricle. Contains many nuclei and infundibulum Has 7 major functions

Question 37

Infundibulum

Answer 37

the stalk connecting the hypothalamus and the pituitary gland

Question 38

Pituitary Gland

Answer 38

Endocrine gland | releases several hormones in response to chemical regulation factors from the hypothalamus

Question 39

Functions of the Hypothalamus

Answer 39

1. Autonomic Nervous System (visceral) control center: important for homeostasis 2. A center for emotional responses and behaviors 3. Body temperature regulation 4. Regulation of food intake 5. Regulation of water balance and thirst 6. Regulation of sleep-wake cycles 7. Controls many endocrine system functions: neuroendocrine feedback control

Question 40

Epithalamus

Answer 40

Found upon the Thalamus in the dorsal portion of the Diencephalon Contains the pineal gland: melatonin/sleep-wake cycles Location of one of the choroid plexus sites for production of cerebrospinal fluid (CSF)

Question 41

Brain Stem

Answer 41

``` Brain region composed of the midbrain, pons, and medulla Involved in automatic, unconscious behaviors needed for survival Provides pathways (fiber tracts) for neurons which are communicating up or down ```

Question 42

Midbrain

Answer 42

Part of the brain stem Pons to the lower portion of the diencephalon with the cerebral aquaduct passing through it Main connecting routes for all parts of the brain and spinal cord Connections between the cerebellum and the brainstem (cerebellar peduncles)

Question 43

Pons

Answer 43

Part of the brain stem Found above the medulla and anterior to the cerebellum Contains both gray matter nuclei and white fiber tracts Primarily conduction pathways Site of origin for several cranial nerves Cerebral peduncles

Question 44

Medulla Oblongata

Answer 44

Part of the brain stem Most inferior part of the brain that merges into the spinal cord inferiorly Involved in maintaining internal homeostasis Contains: cardiovascular center, respiratory center, and other centers for vomiting, hiccupping, swallowing, coughing and sneezing

Question 45

Cerebellum

Answer 45

Second-largest brain region "small brain" Separated from the cerebrum by the transverse fissure Its surface is the cerebellar cortex (gray matter) with folds (folia); its white matter fiber tracts are located in the interior arbor vitae: "tree of life"

Question 46

Cerebellar Structure and Function

Answer 46

Shaped like a butterfly Central vermis "worm" cerebellar hemispheres Functions compare an intended movement (directed from the cortex) with what movement is actually happening Constantly receiving sensory input from muscle, tendon, and joint proprioceptors, and visual and equilibrium receptors Purkinje neurons play a major role in control over the refinement of motor activities inititiated by the frontal motor cortex

Question 47

Homunculi

Answer 47

maps of the functional area

Question 48

The Limbic System

Answer 48

Encircles the brain stem Emotional center Different regions of gray matter, including part of the hypothalamus and the olfactory bulbs Funcions in emotional aspects of behavior related to survival "fight or flight" Memory impairment results from damage to the limbic system Also associated with pleasure and pain: electrical stimulation elicits different responses; includes defensive posturing (rage); others inspire timidity Also functions with the cerebrum in memory: olfactory centers are near the limbic system; and experiences which initiate strong emotional responses are associated with smells are committed to memory more easily

Question 49

Reticular Formation

Answer 49

``` Gray matter (nuclei) distributed within the medulla, pons, and midbrain Axonal connections to many other areas of the brain Structural and functional areas: sensory, integrative and motor functions; receives input from higher centers for skeletal muscle actions ```

Question 50

Reticular Activating System (RAS)

Answer 50

1. Functions to alert the cerebral cortex to important incoming signals 2. Filters signal "noise" = repetitive stimuli (LSD interferes with this: constantly "your shirt is on" "this person is chewing gum") 3. Maintenance of consciousness and waking from sleep (sudden stimuli): sends a constant stream of information to the cortex, maintaining arousal 4. The RAS is inhibited by sleep centers in the hypothalamus 5. The RAS is depressed by alcohol, sleep-inducing drugs (hypnotics) and anti-anxiety drugs.

Question 51

Protection of the brain

Answer 51

1. bones: skull 2. meninges: three connective tissue wrappings the CNS 3. cerebrospinal fluid (CSF): a fluid "shock absorber" which cusions and nourishes the brain 4. blood-brain barrier: the physical and physiological separation of the CNS from the bloodstream (scalp hair to prevent sunstroke?)

Question 52

Functions of the Meninges

Answer 52

1. Covers and protects brain and spinal cord 2. Protect blood vessels and enclose venous sinuses 3. Confine the cerebrospinal fluid in the subarachnoid space 4. Form major connective tissue partitions for brain regions within skull: falx cerebri (in longitudinal fissure), falx cerebelli, tentorium cerebelli (transverse fissure)

Question 53

Dura Mater

Answer 53

Outermost layer of the meninges "tough mother" Dense, irregular fibrous connective tissue Strong, protective wall around the brain and spinal cord Pool of venous (deoxygenated) blood

Question 54

Arachnoid Membrane

Answer 54

Middle layer of the meninges Loose connective tissue Subdural space (gap): separates the arachnoid from the dura; contains interstitial fluid Arachnoid vili: extend into the subdural space creating larger surface area for reabsorption of CSF back into the blood Subarachnoid Space: separates arachnoid from the pia mater; contains CSF

Question 55

Pia Mater

Answer 55

Deepest layer of the meninges "little mother" Extends into the sulci and follows the large blood vessels into the brain Thin/light transparent fibrous connective tissue supporting a network of many tiny blood vessels

Question 56

Cerebrospinal Fluid

Answer 56

Protects against chemical and physical injury serving as secondary circulatory system nourishing the CNS Found in the four ventricles and the subarachnoid space Composition: H20, clucose, proteins, lactic acid, urea, cations (Na+, K+, Ca2+, Mg2+), anions (Cl-, HCO3-), some lymphocytes (WBCs) 80-150ml of CSF is normal for an adult Formed by the choroid plexus; reabsorbed by the arachnoid villi and returned to the plasma

Question 57

Functions of Cerebrospinal Fluid

Answer 57

1. Mechanical Protection: shock absorbing fluid; the brain "floats" in this fluid 2. Chemical Protection: provides a constant chemical environment; the pH of the CSF is important in the control of breathing; CSF composition is important for regulating cerebral blood flow 3. Circulation for the exchange of nutrients and waste products between the blood and nervous tissue

Question 58

Choroid Plexus

Answer 58

Where the CSF is formed Special capillary networks in certain palces in the ventricular walls Ependymal cells (glial cells of the CNS:barriers between brain tissue of fluid sacs (CSF)) Fluid from plasma passes through the ependymal cells Cells have ion pumps that modify CSF and regulate and maintain the blood-brain barrier Protect the brain from harmful substances in the blood

Question 59

Blood-brain barrier

Answer 59

Penetration of molecules from the blood is regulated by: 1. Tight junctions between capillary cells. They prevent molecules from going in between the gaps and cells 2. Thick basal lamina (connective tissue layer) 3. Astrocytes (glial cells of the CNS that help anchor neurons to nearby blood capillaries) pressed against capillaries The barrier is a selective membrane 1. Most charged ions do not pass easily 2. Proteins and most antibiotics do not pass at all 3. Some substances, particularly if lipid-soluable, pass easily from blood to the brain (water, glucose, O2, CO2, alcohol, caffeine, nicotine, heroin, most anesthetics)

Question 60

Blood Brain Barrier Cont.

Answer 60

Permeability is variable depneding on the site 1. choroid plexus: CSF production 2. vomiting center in the brain: monitors the blood for toxic molecules and poison 3. Hypothalamus: has no blood brain barrier; monitors blood compositition for water balance, temperature, pH, osmolarity and many other homeostatic metabolic functions

Question 61

Parts of the brain with no effective blood-brain barrier

Answer 61

Hypothalamus Choroid Plexus Vomiting Center (on medulla oblongata)

Question 62

Concussion

Answer 62

A blow to the head The skull stops but the brain keeps moving Brain bounces off the inside of the skull Possibly, there is no visible external damage A variety of cognitive problems follow

Question 63

Contusion

Answer 63

Breaks in small vessels, some bleeding, visible bruising | Effect depends on the location

Question 64

Laceration

Answer 64

Tearing of the brain | Major traumas such as knife and gunshot wounds

Question 65

Epidural or subdural or subarachnoid hemorrhage

Answer 65

bleeding from ruptured vessels into that space person is normal immediately after the injury, but deteriorates as the bleeding continues hemorrhage increases intracranial pressure effects vary with the location of the hematoma Surgical intervention: drill holes (Izzy on Grey's Anatomy during ferry accident), remove clots, install drainaige tubes

Question 66

Stroke

Answer 66

Cerebrovascula Accident (CVA) Ischemia anemia caused by reduced or blocked blood flow hemorrhages nad blood clots increase intracranial pressure brain tissue dies (infart) risk factors: high bp, high cholesterol, heart disease, narrowed carotoid arteries, diabetes, smoking, obesity, excessive alcohol intake third leading cause of death in the US (wonder why....hello)

Question 67

Transient Ischemic Attack (TIA/ministroke)

Answer 67

type of cerebrovascular accident may last minutes flow is reduced and brain tissue suffers temporarily blood flow is re-established

Question 68

Alzheimer's disease

Answer 68

Degenerative brain disease Widespread cognitive deficits: (short term) memory loss, shortened attention span and disorientation, loss of language skills Death from secondary causes; difficulty responding to difficult events. Ex: fire in your house Diagnosis is difficult since there is no definitive test except during autopsy Significant loss of neurons in specific regions Abnormal proteins are deposited in the brain tissue Tangled nerve masses Generally, the damage is limited to the cerebral cortex Brain is aware of what is going on, but doesn't know how to deal with it

Question 69

Parkinson's Disease

Answer 69

Degenerative brain disease progressive disorder of the CNS which typically affects victims at age 60 or so characterized by degeneration of dopamine-releasing neurons, tremor (shaking), and rigidity (continues contractions) Motor performance impaired by bradykinesia (slow motion) and hypokinesia (reduced range of motion) Treatments try to increase dopamine and decrease ACh with theraputic drugs or by experimental implantation of fetal brain cells

Question 70

Cerebral Palsy

Answer 70

Degenerative Brain Disease Damage to the motor areas of brain during fetal life, at brith, or during infancy, and usually transient 02 deprivation Poor control and coordination of voluntary muscle activities but usually little impact on intellect Irreversible, but not progressive Thinking is fine, but communication is limited to victims often seem mentally retarded

Question 71

Anatomy and Protection of the Spinal Cord

Answer 71

Located within the vertebral column Passes through the vertebral foramina Spinal meninges (dura mater, arachnoid, pia mater) cover spinal cord and nerves Epidural space between the dura mater and wall of the verterbral column (where epidural is administered during childbirth) Nerves exit through interverterbal foramina CSF is protection mechanism

Question 72

External Spinal Cord Anatomy

Answer 72

From formen magnum to second lumbar vertebra (L2) About 2cm wide and 42-45 cm long Ends in the conus medullaris between L1 and L2 Cervical enlargement and lumbar enlargement

Question 73

Cervical enlargement

Answer 73

enlarged area of the spinal cord for nerves for upper extremities to control arms

Question 74

Lumbar enlargement

Answer 74

enlarged area of spinal cord for nerves for lower extremities to control legs

Question 75

Filum terminale

Answer 75

pia mater | extends from the conus to attach the spinal cord to the coccyx

Question 76

cauda equina

Answer 76

"horse's tail" at the end of the cord are the last few pairs of spinal nerves that exit the vertebral column below the level of their exit from the spinal cord

Question 77

Cross_sectional anatomy of the Spinal Cord

Answer 77

H shaped gray matter surrounded by butterfly white matter Anterior median fissure Posterior medial sulcus Gray commisure Central Canal: small space in the middle of gray commissure; extends length of spinal cord; at superior end continues with the 4th ventricle; contains CSF

Question 78

Gray Commissure

Answer 78

forms the cross bar of the 'H' Link where info goes from one side of CNS to the other Ex: corpus callosum

Question 79

Anterior white commissure

Answer 79

Anterior to the gray commissure | Link where info goes from one side of the CNS to the other

Question 80

Anterior (ventral) gray horns

Answer 80

In gray matter visceral and somatic motor neurons neurons, cell bodies, soma

Question 81

Posterior (dorsal) gray horns

Answer 81

gray matter | fibers from somatic and visceral sensory neurons (cell bodies = soma)

Question 82

Lateral Gray Horns

Answer 82

gray matter between anterior and posterior horns present only in thoracic, upper lumbar, and sacral segments

Question 83

Ventral Root

Answer 83

gray matter | Efferent (motor) nerves(cell axons) to skeletal muscles and to the visceral organs (effectors)

Question 84

Dorsal Root

Answer 84

gray matter Afferent (sensory) nerves (cell axons) from skin, skeletal muscles, connecive tissues, visceral organs Unipolar (1 process)

Question 85

Visceral Motor (VM)

Answer 85

organs smooth and cardiac muscle involuntary movement peristalsis (digestions)

Question 86

Somatic Motor Neurons (SM)

Answer 86

control skeletal muscle | voluntary movement

Question 87

White Matter of the Spinal Cord

Answer 87

Conduction Tracts (collections of myelinated axons going from one place to another) in the spinal cord Named by where each is coming from and where each is going More superficial areas Fasciculi cuneatus and gracilis: fine touch and pressure Lateral and anterior spinothalamic tracts: pain, temperature, deep pressure, and coarse touch Two paths for similar functions