Chapter 9: Physio

plasticity

restructure of the brain networks in response to sensory input and experience

affective

behaviors are related to feeling and emotion

cognitive

behaviors are related to thinking

unicellular organisms

do not have integrating centers, but use membrane potentials to coordinate activity

cnidaria

have a nervous system termed a nerve net

flatworms

have primitive brains and nerve cords

anelids

simple brains and ganglia along nerve cords

simple reflexes

integrated at the ganglia WITHOUT the brain

most dramatic change is seen in the

forebrain (cerebellum)

Anatomy of nervous system

The CNS develops from a hollow tube

Begins as a group of cells called the neural plate

Plate fuses to create a neural tube, by about day 23

By week 4 anterior portion differentiates into specialized regions

Forebrain, midbrain, and hindbrain

By week 6, the 7 divisions of the CNS are present

Forebrain becomes cerebrum and diencephalon

Hindbrain becomes cerebellum, pons, and medulla oblongata- Formation of the ventricles

By week 11, the cerebrum is enlarged

Surrounds the diencephalon, midbrain, and pons

Cerebellum and medulla oblongata remain visible

CNS

brain and spinal cord

gray matter of the CNS

unmyelinated nerve cell bodies, clusters of cell bodies in CNS are nuclei, dendrites, axon terminals

white matter of the CNS

myelinated axons, axon bundles connecting CNS regions are tracts, FEW cell bodies

the brain is encased in

bony skull or cranium

meninges

lie between bone and tissues to stabilize neural tissue and protect from bruising / extracellular fluid cushion

cerebrospinal fluid (CSF)

salty solution similar to plasma

where is the cerebrospinal fluid produced

choroid plexus in ventricles

what does the cerebrospinal fluid surround

entire brain

CSF functions in

physical and chemical protection

astrocytes foot

promotes tight junctions between endothelial cells

blood brain barrier

protects brain from toxic water soluble compounds and pathogens

brain receives what percentage of blood pumped by heart

15%

oxygen

passes freely across blood-brain barrier

glucose

membrane transporters moves glucose from plasma into the brain interstitial fluid

progressive hyperglycemia leads to

confusion, unconsciousness, and death

two branches of the spinal nerve

dorsal root and ventral root

the dorsal root carries

afferent (sensory) information

the ventral root carries

motor information form CNS --> muscles and glands

dorsal horns contain

visceral and somatic sensory nuclei

lateral horns contain

visceral motor nuclei

ventral horns contain

somatic motor nuclei

white matter division (2)

ascending tracts and descending tracts

ascending tracts

takes sensory information to the brain

descending tracts

carries motor signals away from the brain

propriospinal tracts

stays in the cord

what is the oldest part of the brain

brain stem

how many cranial nerves originate from the brain stem

11 out of 12

medulla

controls INVOLUNTARY functions: blood pressures, breathing, swallowing, vomiting

pons

Relay station, coordinates control of breathing

midbrain

Eye movement, relay signals for hearing and seeing reflexes

cerebellum

Process sensory information and coordinate the execution of movement / equilibrium and balance from somatic receptors

thalamus

Relay station integrating center

hypothalamus

Control of homeostasis / Center for behavioral drives: for example, hunger, thirst, / Influences autonomic function and endocrine function

endocrine structures

anterior and posterior pituitary / pineal gland

diencephalon

consists of thalamus, hypothalamus, pineal gland, and pituitary gland

functions of hypothalamus

1. Activates sympathetic nervous system

• Controls catecholamine release from adrenal medulla (as infight-or-flight reaction)

• Helps maintain blood glucose concentrations through effects on endocrine pancreas

• Stimulates shivering and sweating

2. Maintains body temperature

3. Controls body osmolarity

• Motivates thirst and drinking behavior

• Stimulates secretion of vasopressin [p. 207]

4. Controls reproductive functions• Directs secretion of oxytocin (for uterine contractions and milk release)• Directs trophic hormone control of anterior pituitary hormones FSH and LH [p.211]

5. Controls food intake

• Stimulates satiety center

• Stimulates feeding center

6. Interacts with limbic system to influence behavior and emotions

7. Influences cardiovascular control center in medulla oblongata

8. Secretes trophic hormones that control release of hormones from anterior pituitary gland

cerebrum categories

gray matter and white matter

gray matter of the cerebrum

- Cerebral cortex

- Basal ganglia: control of movement

- Limbic system: link between cognitive functions and emotions

includes amygdala and hippocampus

amygdala and cingulate gyrus

emotion and memory

hippocampus

learning and memory

white matter of the cerebrum

Bundles of fibers connecting the different regions of the brain / mainly INTERIOR

brain functions (3)

sensory system, cognitive system, behavioral state system

sensory system of the brain

monitors internal and external environments / imitates reflex response

cognitive system of the brain

initiates voluntary response

behavioral system of the brain

governs sleep wake cycles and other intrinsic behaviors

cerebral cortex functional areas

sensory areas, motor areas, association areas

sensory areas of the cerebral cortex

translates into perception (awareness)

motor areas of the cerebral cortex

directs skeletal movement

association areas of the cerebral cortex

integrates information from sensory and motor areas / directs voluntary behaviors

primary somatic sensory cortex

termination point of pathways from skin, musculoskeletal system, and viscera

somatosensory pathways

Touch, temperature, pain, itch, body position

special senses

Visual cortex, auditory cortex, olfactory cortex, gustatory cortex

three major types of output from CNS

skeletal muscle movement, neuroendocrine signals, visceral responses

skeletal muscle movement of the CNS

somatic motor division

neuroendocrine signals of the CNS

hypothalamus and adrenal medulla

visceral responses of the CNS

autonomic division

voluntary movement of the CNS

primary motor cortex and the motor association areas

behavioral state system modulates

sensory and cognitive processes

reticular activating system

controls consciousness

Electroencephalogram (EEG)

measures brain activity

diffuse modulatory systems

noradrenergic, serotonergic, dopaminergic, cholinergic

noradrenergic functions

Attention, arousal, sleep-wake cycles, learning, memory, anxiety, pain, and mood

serotonergic functions

Lower nuclei: Pain, locomotion

Upper nuclei: Sleep-wake cycle; mood and emotional behaviors, such as aggression and depression

dopaminergic functions

Motor control

"Reward" centers linked to addictive behaviors

cholinergic functions

Sleep-wake cycles, arousal, learning, memory, sensory information passing through thalamus

four stages of sleep

N1, N2, N3, REM

stage N3 (slow-wave sleep)

Adjusts body without conscious commands

REM sleep

dreaming takes place / Brain activity inhibits motor neurons to skeletal muscle, paralyzing them

insomnia

inability to sleep

sleep apnea

stopping normal breathing during sleep

somnabulism

sleepwalking

the deepest sleep occurs in the

first three hours

circadian rhythm

alternating daily patterns of rest and activity

primary clock

Suprachiasmatic nucleus (SCN) of the hypothalamus / Melatonin linked to circadian rhythms

limbic system

center of emotion in the human brain

motivation

internal signals that shape voluntary behaviors

When do motivated behaviors stop?

when a person has reached a certain level of satiety

what is linked to dopamine

pleasure and addictive behaviors

moods

one's sense of well being

depression

▪ Sleep and appetite disturbances

▪ Alterations of mood and libido

▪ May affect function at school or work or in personal relationships

▪ Antidepressant drugs alter synaptic transmission

learning

acquisition of knowledge

types of learning

associative and nonassociative learning

nonassociative learning

habituation and sensitization

memory

ability to retain and recall information

Anterograde amnesia

inability to remember new memories

integration of spoken language involves two regions

Wernicke's area and Broca's area

Wernicke's area

understanding language

Broca's area

produces speech

Damage to Wernicke's area

receptive aphasia - unable to understand sensory input

Damage to Broca's area

expressive aphasia - unable to understand complicated sentences with multiple elements, possible deficit in short-term memory, difficulty speaking or writing normal syntax