the ability of cells to respond to the environment has evolved over billions of years

The ability of cells to respond to the environment has evolved

over billions of years

• Nerve nets.

Nervous systems show diverse patterns of organization

• With cephalization come more complex nervous systems.

• Functional composition of the PNS.

Fig. 48.17

Parasympathetic and Sympathetic Nervous System:

• A subdivision of the PNS• Not under conscious control• Work antagonistically• Controlled by medulla oblongata and

hypothalamus• Peripheral nervous system that

supplies stimulation via motor nerves to smooth and cardiac muscle and to glands

neurotransmitter is norepinephrine, fight or flight

E = exercise, excitement, emergency, and embarrassment

neurotransmitter is acetylcholine

D = digestion, deification, diuresis (urinating)

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

Fig. 48.20

cerebrum corpus callosum

thalamus

cerebellum

medulla oblongata

hypothalamus

pituitary

pons

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 are specialized for different functions

• Frontal lobe.– Contains the primary motor cortex.

• Parietal lobe.– Contains the primary somatosensory cortex.


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 are planned.


• The brain exhibits plasticity of function.– For example, infants with intractable

epilepsy may have an entire cerebral hemisphere removed.• The remaining hemisphere can provide the

function normally provided by both hemispheres.


• Lateralization of Brain Function.– The left hemisphere.

• Specializes in language, math, logic operations, and the processing of serial sequences of information, and visual 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

Generating words

Max

Speaking words

Hearing words

Seeing words

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 involved generating 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 recognizing the 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 are stored 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 mechanisms

similar to those involved in brain growth and development.


• 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.


• 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 development and neural stem cells may lead to new approaches for treating CNS

injuries 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 cannot

undergo cell division the new cells must have arisen from stem cells.


Thalamus

• Relay center for sensory tracts from the spinal cord to the cerebrum.

• Contains centers for sensation of pain, temperature, and touch.

• Involved with emotions and alerting or arousal mechanisms.

• The Reticular System, Arousal, and Sleep.

– The reticular activating system (RAS) of the reticular formation.• Regulates sleep

and arousal.• Acts as a

sensory 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 during REM (rapid eye movement) sleep.


Fig. 48.22b-d

Hypothalamus

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

• body temperaturebody temperature• water balance and thirstwater balance and thirst• sleep/wake cyclessleep/wake cycles• appetiteappetite• sexual arousalsexual arousal• control of endocrine functioning:control of endocrine functioning:Acts on the pituitary gland through the Acts on the pituitary gland through the

release of neurosecretions.release of neurosecretions.

Regulates:Regulates:

Hypothalamus

Pituitary

• Cerebellar peduncles• Tectum• Superior colliculi• Inferior colliculi• Substantia nigra• Red nuclei

Midbrain

thalamus

Red nucleus

Substantia nigra

Tectu

mPosterior

Anterior

Midbrain

• Contains ascending and descending tracts to the cerebrum and thalamus.

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

and auditory information (connects head movements with visual and auditory stimuli).

Pons

• Connects the two halves of the cerebellum.

• Regulates breathing.

Medulla Oblongata• Composed of nerve tracts

to 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 OblongataContains control centers for Contains control centers for many subconscious many subconscious activitiesactivities• Respiratory rateRespiratory rate• Heart rateHeart rate• Arteriole constrictionArteriole constriction• SwallowingSwallowing• HiccuppingHiccupping• CoughingCoughing• SneezingSneezing

Cerebellum

• Controls and coordinates muscular activity.

• Important in equilibrium, posture and movement.

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

1. Olfactory- smell2. Optic- vision3. Oculomotor- 4 of the 6 extrinsic eye muscles 4. Trochlear- extrinsic eye muscles5. Trigeminal- sensory fibers to the face and motor fibers to

the chewing muscles6. Abducens- controls eye muscles that turn the eye laterally7. Facial- facial expression8. Vestibulocochlear- hearing and balance9. Glosopharyngeal- tongue and pharynx10.Vagus- parasympathetic control of heart, lungs &

abdominal organs11.Accessory- accessory part of vagus nerve, neck & throat

muscles12.Hypoglossal- moves muscles under tongue

Olfactory

Optic

Oculomotor

Trochlear

Trigeminal

Abducens

VestibulocochlearGlossopharyngeal

VagusAccessory Hypoglossal

Facial

Degenerative brain diseases

• Schizophrenia• Parkinson’s• Alzheimer’s• Huntington’s Chorea• MS• Epilepsy

Parkinson’s disease

• Substantia nigra in midbrain• Dopamine

- affects brain processes controlling:• movement• balance• walking• emotional response• ability to experience pleasure

and pain.

Parkinson’s diseaseCauses:• 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).


Treatments:• L-dopa• Deprenyl• Deep brain stimulation w/electrodes• Fetal tissue


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

the ability of cells to respond to the environment has evolved over billions of years

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