Ch 49 Nervous Systems

7/29/2019 Ch 49 Nervous Systems

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The ability of cells to respond to

the environment has evolvedover billions of years



• Nerve nets.

Nervous systems show diversepatterns of organization



• With cephalization come more complex

nervous systems.





• Functional composition of the PNS.

Fig. 48.17





Parasympathetic and SympatheticNervous System:• A subdivision of the PNS

• Not under conscious control

• Work antagonistically

• Controlled by medulla oblongata and

hypothalamus

• Peripheral nervous system thatsupplies stimulation via motor nerves

to smooth and cardiac muscle and to

glands



neurotransmitter is norepinephrine, fightor flight

E = exercise, excitement, emergency, and

embarrassment

neurotransmitter is acetylcholine

D = digestion, deification, diuresis (urinating)










http://slidepdf.com/reader/full/ch-49-nervous-systems 14/52Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 48.20



cerebrum corpuscallosum

thalamus

cerebellum

medullaoblongata

hypothalamus

pituitarypons

spinal cord

Pineal gland



Cerebrum

• Involved with higher brain functions.• Processes sensory information.

• Initiates motor functions.

• Integrates information.



• The

cerebrum is

divided into

frontal,

temporal,

occipital,and parietal

lobes.

Regions of the cerebrum arespecialized for different functions



• Frontal lobe. – Contains the primary motor cortex.

• Parietal lobe. – Contains the primary somatosensory cortex.



Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Fig. 48.25



• Integrative Function of the Association Areas.

– Much of the cerebrum is given over to

association areas. • Areas where sensory information is integrated

and assessed and motor responses areplanned.




• The brain exhibits plasticity of function.

– For example, infants with intractable

epilepsy may have an entire cerebralhemisphere removed.

• The remaining hemisphere can provide thefunction normally provided by bothhemispheres.




• Lateralization of Brain Function.

– The left hemisphere.

• Specializes in language, math, logic operations, andthe processing of serial sequences of information, andvisual and auditory details.

• Specializes in detailed activities required for motor

control. – The right hemisphere.

• Specializes in pattern recognition, spatial relationships,nonverbal ideation, emotional processing, and the

parallel processing of information.


Fig 49-17



Fig. 49-17

Generatingwords

Max

Speakingwords

Hearingwords

Seeingwords

Min



• Language and Speech.

– Broca’s area. • Usually located in the left hemisphere’s frontal lobe • Responsible for speech production.

– Wernicke’s area. • Usually located in the right hemisphere’s temporal lobe

• Responsible for the comprehension of speech.

– Other speech areas are involvedgenerating verbs to match nouns, grouping

together related words, etc.




• Emotions.

– In mammals, the limbic system is composed

of the hippocampus, olfactory cortex, inner portions of the cortex’s lobes, and parts of the

thalamus and hypothalamus.

• Mediates basic emotions (fear, anger), involved in

emotional bonding, establishes emotional memory

– For example,

the amygdala

is involved in

recognizingthe emotional

content of

facial expression.



• Memory and Learning.

– Short-term memory stored in the frontal

lobes.

– The establishment of long-term memory

involves the hippocampus.

• The transfer of information from short-term to

long-term memory.

– Is enhanced by repetition (remember that when you are

preparing for an exam).

– Influenced by emotional states mediated by the

amygdala.

– Influenced by association with previously stored

information.




– Different types of long-term memories arestored in different regions of the brain.

– Memorization-type memory can be rapid.• Primarily involves changes in the strength of

existing nerve connections.

– Learning of skills and procedures is slower.• Appears to involves cellular mechanismssimilar to those involved in brain growth anddevelopment.




• Human Consciousness.

– Brain imaging can show neural activity

associated with:• Conscious perceptual choice

• Unconscious processing

• Memory retrieval• Working memory.

– Consciousness appears to be a whole-brain phenomenon.


R h d l



• The mammalian PNS has the ability to repair

itself, the CNS does not.

– Research on nerve cell development and

neural stem cells may be the future of

treatment for damage to the CNS.

Research on neuron developmentand neural stem cells may lead to

new approaches for treating CNSinjuries and diseases




• Neural Stem Cells.

– The adult human brain does produce new

nerve cells.• New nerve cells have been found in the

hippocampus.

• Since mature human brain cells cannotundergo cell division the new cells must havearisen from stem cells.




Thalamus

• Relay center for sensory tracts

from the spinal cord to thecerebrum.

• Contains centers for sensation

of pain, temperature, and touch.• Involved with emotions andalerting or arousal mechanisms.



• The Reticular System, Arousal, and Sleep.

– The reticular activating system (RAS) of

the reticular formation.

• Regulates sleep

and arousal.

• Acts as asensory filter.


Fig. 48.21



– Sleep and wakefulness produces patterns

of electrical activity in the brain that can be

recorded as an electroencephalogram(EEG).

• Most dreaming

occurs duringREM (rapid

eye movement)

sleep.


Fig. 48.22b-d



Hypothalamus

• autonomic control center- blood pressure,rate and force of heart contraction, center for emotional response and behavior

• body temperature• water balance and thirst• sleep/wake cycles

• appetite• sexual arousal• control of endocrine functioning: Acts on the pituitary gland through the

release of neurosecretions.

Regulates:



Hypothalamus

Pituitary



Pituitary

Midbrain



• Cerebellar peduncles

• Tectum

• Superior colliculi• Inferior colliculi

• Substantia nigra

• Red nuclei

Midbrain

thalamus

Red nucleus

Substantia nigra

Posterior

Anterior



Midbrain

• Contains ascending and descendingtracts to the cerebrum andthalamus.

• Reflex center for eye muscles.• Also involved with processing visual

and auditory information (connects

head movements with visual andauditory stimuli).



Pons

• Connects the two

halves of the

cerebellum.

• Regulates breathing.



Medulla Oblongata

• Composed of nerve tractsto and from the brain

(these tracts cross over

left to right and right to left)• May be regarded as an

extension of the spinal

cord• Almost all of the cranial

nerves arise from this

region



Medulla Oblongata

Contains control centers for many subconscious

activities

• Respiratory rate• Heart rate

• Arteriole constriction

• Swallowing• Hiccupping

• Coughing

• Sneezing



Cerebellum

• Controls and coordinatesmuscular activity.

• Important in equilibrium,

posture and movement.



On Old Olympus Towering Tops A Fat Voracious German Viewed A Hop

1. Olfactory- smell

2. Optic- vision

3. Oculomotor- 4 of the 6 extrinsic eye muscles

4. Trochlear- extrinsic eye muscles

5. Trigeminal- sensory fibers to the face and motor fibers to

the chewing muscles

6. Abducens- controls eye muscles that turn the eye laterally

7. Facial- facial expression

8. Vestibulocochlear- hearing and balance

9. Glosopharyngeal- tongue and pharynx

10.Vagus- parasympathetic control of heart, lungs &

abdominal organs

11.Accessory- accessory part of vagus nerve, neck & throat

muscles

12.Hypoglossal- moves muscles under tongue



OlfactoryOptic

Oculomotor

Trochlear

Trigeminal

Abducens

Vestibulocochlear Glossopharyngeal

Vagus Accessory Hypoglossal

Facial



Degenerative brain diseases

• Schizophrenia

• Parkinson’s

• Alzheimer’s • Huntington’s Chorea

• MS

• Epilepsy

P ki ’ di



Parkinson’s disease

• Substantia nigra in midbrain• Dopamine

- affects brain processes controlling:

• movement• balance

• walking

• emotional response• ability to experience pleasure

and pain.

P ki ’ di



Parkinson’s disease Causes:

• Genetics• Environmental chemicals (e.g., PCBs)

• Thyroid disorders

• Repeated head injury

Symptoms of Parkinson's Disease: • resting tremor on one side of the body

• generalized slowness of movement (bradykinesia)

• stiffness of limbs (rigidity)• gait or balance problems (postural dysfunction).

P ki ’ di




Treatments:• L-dopa

• Deprenyl

• Deep brain stimulation w/electrodes

• Fetal tissue

P ki ’ di




F-Dopa deficiency



Alzheimer’s Disease

Results in dementia

• 5-15% over age 65• 50% over age 85

Associated with :

• Acetylcholine shortage• Amyloid plaques

• Neurofibullary tangles



PET Scans



PET Scans

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Ch 49 Nervous Systems