Block 4 Nervous System

Plasticity

formation of new synapses

Neurogenesis

formation of new neurons

Learning

Neurogenesis & plasticity (new synapses & neurons) in response to information

Afferent Neurons

signal from cranial & spinal nerves → brain & spinal cord sensory information

Efferent Neurons

signal from brain & spinal cord → effector muscle (motor)

Flow of Information

Afferent (sensory) → Integration of sensory info (Interneuron) → Efferent (motor) effector muscle moves

Neuroglia

support, protection & nourishment of neurons

Blood Brain Barrier BBB

maintains stable environment in brain w/ barely permeable capillaries (only CO2 & O2 can enter)

Astrocytes

“ foot processes” surround/compress around vessels managing permeability in BBB

Dura Mater

Most superficial layer creating sinuses & fusing with skull

Arachnoid Mater

cushioning & shock absorption

Pia Mater

thinnest, deepest layer directly covering neurons & neuroglia

Cerebrospinal Fluid (CSF)

filtrate of plasma containing glucose, O2, and other ions

CSF Flow

choroid plexus → lateral ventricles (1&2) → interventricular foramen → 3rd ventricle → cerebral aqueduct → 4th ventricle → central canal OR subarachoid space

Hydrocephalus

buildup of CSF → increased pressure & ventricle size in the brain

Cerebrum

frontal, parietal, insula, occipital, temporal & association & motor areas

Frontal

reasoning, emotions, personality

Parietal

processing information related to touch, temperature, pressure

Temporal

processing auditory stimuli

Occipital

processing visual stimuli

Insula

integrate autonomic information (makes person consciously aware of internal bodily feelings ex. pain perception)

Primary Motor Cortex

sends signals → skeletal muscles → movement precentral gyrus

Primary Somatosensory Cortex

receives sensory signals

Somatosensory Association Area

processes visual signals & allows for recognitiion of objects by touch alone

Motor Association Area

planning & organizing of complex movement

Primary Visual Cortex

receives visual stimuli signals (occipital lobe)

Visual Association Area

processes visual stimuli & allows for recognition of objects by sight (occipital lobe)

Auditory & Olfactory Cortex

recieves signals relating to auditory stimuli and smell (temporal lobe)

Auditory & Olfactory

processes sounds & smell allows for recognition of peoples voices & links certain smells to memories in limbic system (temporal lobe)

Dienchephalon

epithalamus, thalamus, hypothalamus, limbic system

Epithalamus

superior to thalamus houses pineal gland → melatonin → sleep regulation

Thalamus

sensory-motor processing relay station

Hypothalamus

maintains homeostasis (regulates body temp, eating, emotions, etc) & houses pituitary gland

Limbic System

storage & memory retrieval (hippocampus = learning memory; amygdala = emotional memory/ fear)

Cerebellum

propioceptors → coordinate movement → maintain balance & posture

Arbor Vitae

white matter

Folia

gray matter

Brainstem

pons, medulla oblongata, midbrain

Pons

connects cerebral cortex → medulla oblongta & manages respiration ( Apneustic = depth of breathing Pneumotaxic = rate of breathing)

Medulla Oblongata

connects brain → spinal cord maintains HR, BP & controls vegetative functions (coughing, swallowing, etc)

Midbrain

Superior Colliculi (head & trunk movements) & Inferior Colliculi (auditory pathway & startle reflex)

Substantia Nigra

release dopamine → subconscious muscle activity

Red Nucleus

controls voluntary movement of limbs

Nucleus

cluster of neurons in CNS (Tract = axons CNS)

Ganglion

cluster of neurons in PNS (Nerve = axons PNS)

Cerebral White Matter Tracts

Association = axon impulses same hemisphere

Commisural = axon impulse from 1 hemisphere to another

Projection = axon impulse lower end CNS (thalamus)

Basal Nuclei

initiate & terminate movements, regulate muscle tone, control subconscious muscles

Reflex

maintain homesotasis by rapid, automatic reactions to stimuli or change in environment

Reflex Arc

Stimulus → Sensory Receptor → Afferent/Sensory Neuron → Integrating Center → Efferent/Motor Neuron → Effector

Stretch Reflex

monosynaptic, ipsilateral, somatic (change in muscle length)

Stretch Reflex Pathway

stretch (stimulus) → muscle spindle (receptor) → sensory neuron excited → sensory activates motor (integrating center) → motor neuron excited → muscle contracts (effector)

Tendon Reflex

polysynaptic, ipsilateral, spinal, somatic (prevents damage from excess tension → inhibits contraction & relaxes muscle; changes in tension)

Pathway of Tendon Reflex

excess tension (stimulus) → golgi tendon (receptor) → sensory neuron excited → activate inhibitory interneuron (integrating center) → motor neuron inhibited → muscles relaxes (effector) & antagonist motor neuron excited

Flexor Reflex

polysynaptic, ipsilateral, spinal, somatic (contracts muscle in response to pain)

Pathway of Flexor Reflex

Pain in left leg (stimulus) → nociceptors (pain sensor) → sensory neuron excited → several interneurons activated (integrating center) → motor neuron excited → muscle contracts & left leg withdraws (effector)

Crosses Extensor Reflex

polysynaptic, contralateral, spinal, somatic (stabalizes body in response to pain → extends opposing limb)

Pathway of Crossed Extensor Reflex

Pain in left leg (stimulus) → nociceptors → sensory neuron excited → several interneurons activated (integrating center) → motor neuron excited → extensor muscle extends right leg (effector) & flexor muscles contract left leg

C1-C3 Spinal Transection

ventillator required & electric wheelchair

C4-C5 Spinal Transection

diaphragm functional (able to breathe)

C6-C7 Spinal Transection

some arm & chest muscles usable

T1-T3 Spinal Transection

trunk if functional above umbilicus

T4-T9 Spinal Transection

thigh muscles

L1-L2 Spinal Transection

Leg muscles

Contusion

bruising in specific area of brain

Hematoma

blood clot from ruptured vessel

Laceration

torn brain tissue from gunshot/other wound

Traumatic Brain Injury

concussion (repeated consussions → chronic traumatic encephalopathy)