ch 11

Sensory Input

Detects changes (stimuli) via receptors.

Integration

Processes and interprets sensory input.

Motor Output

Sends commands to effectors (muscles/glands).

Homeostasis

Maintains internal conditions (e.g., temperature, pH, glucose).

CNS (Central Nervous System)

Brain and spinal cord; integration and command center.

PNS (Peripheral Nervous System)

Cranial and spinal nerves; divided into sensory (afferent) and motor (efferent) divisions.

Cell Body (Soma)

Contains nucleus and organelles.

Dendrites

Receive signals.

Axon

Transmits impulses away.

Axon terminals

Synapse with other cells.

Astrocytes

are star-shaped glial cells in the brain and spinal cord that support neurons, maintain the blood-brain barrier, and regulate blood flow.

Oligodendrocytes

Supporting cells in the CNS.

Microglia

Supporting cells in the CNS.

Ependymal cells

Supporting cells in the CNS.

Schwann cells

Specialized glial cells that support and insulate axons in the PNS by forming myelin sheaths, facilitating faster electrical impulse conduction.

Satellite cells

are a type of glial cell in the PNS that support and protect neurons, playing a key role in muscle repair and regeneration.

Multipolar Neuron

Many dendrites, one axon (most common).

Bipolar Neuron

One dendrite, one axon (retina).

Unipolar Neuron

One process (sensory neurons).

Synapse

Junction between neurons.

Action Potential (AP)

Threshold reached (~ -55mV); Na⁺ channels open → depolarization; K⁺ channels open → repolarization; Hyperpolarization.

EPSP (Excitatory PostSynaptic Potential)

Depolarization.

IPSP (Inhibitory PostSynaptic Potential)

Hyperpolarization.

Neuron Regeneration

PNS (limited), CNS (very limited).

Acetylcholine

Neurotransmitter at NMJs, parasympathetic.

Dopamine

Neurotransmitter involved in reward and motor control.

Serotonin

Neurotransmitter that affects mood and sleep.

GABA

Main inhibitory neurotransmitter.

Glutamate

Main excitatory neurotransmitter.

Norepinephrine

Neurotransmitter in the sympathetic system.

Meninges

Dura mater, Arachnoid mater, Pia mater.

Gray matter

Central 'H' shape in the spinal cord.

Dorsal horn

Sensory part of the spinal cord.

Ventral horn

Motor part of the spinal cord.

White matter

Contains ascending/descending tracts.

Dorsal columns

Sensory tract for fine touch.

Spinothalamic tract

Sensory tract for pain and temperature.

Corticospinal tract

Motor tract for voluntary movement.

Reflex Arc

Components: Receptor → sensory neuron → integration center → motor neuron → effector.

Patellar Reflex

Stretch reflex.

Golgi Tendon Reflex

Prevents muscle damage.

Withdrawal Reflex

Response to pain.

Cervical Plexus

Phrenic nerve (diaphragm).

Brachial Plexus

Radial, median, ulnar, axillary, musculocutaneous nerves.

Lumbar Plexus

Femoral nerve.

Sacral Plexus

Sciatic nerve.

Spinal Cord Injury Immediate Effects

Paralysis, loss of sensation.

Spinal Cord Injury Long-term Effects

Spasticity, chronic pain, autonomic dysfunction.

Principal Parts of the Brain

Cerebrum, Diencephalon, Brainstem, Cerebellum.

Cerebrospinal Fluid (CSF) Function

Cushioning, nutrient delivery, waste removal.

Cerebrospinal Fluid (CSF) Composition

Clear, plasma-like.

Cerebrospinal Fluid (CSF) Flow

Choroid plexus → ventricles → subarachnoid space → arachnoid granulations → venous system.

Blood Supply to the Brain

Internal carotid, vertebral arteries → Circle of Willis.

Blood-Brain Barrier (BBB)

Selective permeability, protects brain.

Cerebral Cortex Functions

Frontal: Motor, decision-making; Parietal: Sensory; Temporal: Hearing, memory; Occipital: Vision.

Basal Nuclei

Motor control, movement initiation.

Thalamus

Relay station.

Hypothalamus

Homeostasis, endocrine.

Epithalamus

Pineal gland.

Midbrain

Vision, hearing reflexes.

Pons

Breathing regulation.

Medulla Oblongata

Cardiovascular/respiratory centers.

Cerebellum Function

Coordinates voluntary movement, posture, and balance.

Common CNS Disorders

Stroke, Multiple Sclerosis, Parkinson's, Alzheimer's, Epilepsy.

Cranial Nerve I

Olfactory: Smell, Sensory.

Cranial Nerve II

Optic: Vision, Sensory.

Cranial Nerve III

Oculomotor: Eye movement, Motor.

Cranial Nerve IV

Trochlear: Eye movement, Motor.

Cranial Nerve V

Trigeminal: Face sensation, Mixed.

Cranial Nerve VI

Abducens: Eye movement, Motor.

Cranial Nerve VII

Facial: Facial expression, Mixed.

Cranial Nerve VIII

Vestibulocochlear: Hearing/balance, Sensory.

Cranial Nerve IX

Glossopharyngeal: Taste, swallowing, Mixed.

Cranial Nerve X

Vagus: Parasympathetic, Mixed.

Cranial Nerve XI

Accessory: Shoulder movement, Motor.

Cranial Nerve XII

Hypoglossal: Tongue movement, Motor.

Major Nerves of the Brachial Plexus

Axillary: Deltoid; Radial: Posterior arm; Median: Anterior forearm, hand; Ulnar: Medial forearm, hand; Musculocutaneous: Anterior arm.

Major Nerves of the Lumbosacral Plexus

Femoral: Anterior thigh; Obturator: Medial thigh; Sciatic: Largest, posterior thigh; Branches: Tibial, Common fibular nerves.

Exteroceptors

External stimuli (e.g., touch).

Interoceptors

Internal stimuli (e.g., pH).

Proprioceptors

Position, movement of body parts.

Somatic Nervous System

Voluntary, skeletal muscles, single neuron pathway.

Autonomic Nervous System

Involuntary, smooth/cardiac muscle, glands. Two-neuron chain.

Sympathetic Nervous System

"Fight or flight"; Thoracolumbar; Increases HR, BP, dilates pupils.

Parasympathetic Nervous System

"Rest and digest"; Craniosacral; Decreases HR, stimulates digestion.

Cholinergic Neurotransmitters

Acetylcholine (ACh); All preganglionic and parasympathetic postganglionic.

Adrenergic Neurotransmitters

Norepinephrine (NE); Most sympathetic postganglionic.