Nervous System

CNS= central NS; PNS= peripheral NS

Central NS: brain & spinal cord (housed in bone) fxn=integration

Peripheral NS: physically connected to CNS; includes nerves, ganglia, receptors; fxn=deliver info to/from CNS

  • sensory division= deliver info to CNS;

    • general=bodywide (pain, touch pressure, vibration, temp, proprioceptio- your sense of where your different body parts are relative to another)

    • special senses= req organ in head (vision, smell, taste, hearing, equilibrium-head position+movement)

  • motor divison=deliver info from CNS to effectors

    • somatic (voluntary)= skeletal muscle effector (conscious control) (subconscious control)

    • autonomic (involunt)= cardiac MT, smooth MT, glands

      • sympathetic response (flight vs fight response)

      • parasympathetic response (maintain homeostasis; conserve energy)

one of the 4 major tissue types

nerve is an organ, neuron is a cell

reflex: involuntary response to stimulus

Basic Organization

communication, control, coordination “the 3 C’s”

Cells: neurons + neuroglia

Tissue: NT (gray matter and white matter)

  • tissue builds the organs

  • 2 organs in PNS: nerves, ganglia

  • 2 organs in CNS: brain, spinal cord

  • forms the organ system: NS

Neurons and Glial cells in NS

Neuron Classification:

Functional types:

  • sensory, interneurons, motor neurons

Structural types:

  • unipolar, bipolar, multipolar

Reflex Arc: What are the 5 types?

the structures/anatomy that allow you to observe a reflex

  1. sensory receptor

  2. sensory neuron

  3. intraneuron: are all in the CNS

  4. motor neuron:

  5. effector: muscle (contract) or a gland (secrete)

Vocab:

  • dendrites: branching. collecting information from another neuron and sending that information to another body

  • axon: end of a nerve cell

  • multipolar neuron:

  • bipolar neuron: a few sensory neurons are bipolar

  • pseudounipolar: only one extension (looks like 2)

  • Nissl substance: rough ER. extends into dendrites but not axons

Glial

The 6 Glial cells:

  1. astrocyte: physically hold things together (no CT in brain) (found in CNS) fxn=physical support. holds capillaries w/ perivascular meat

  2. microglial cell: found in CNS, resident phagocyte

  3. ependymal cells: line the tiny opening that runs through the spinal cord and tiny spaces in brain: ventricles

  4. oligodendrocyte: form a myelin sheath

    forms the white matter

  5. sensory neurons w Schwann cells: they myelate axons in the PNS. have to have gaps btwn schwann cells (nodes of ranvier)

  6. satellite cells: pass nutrients to unipolar neuron. found in PNS

Vocab:

  • parivascular foot: form blood brain barrier . prevents medicine from going to the brain. protect brain from strange chemicals in the body

  • phagocyte: a cell that eats things

the NS is divided into CNS and PNS

  • PNS gets divided into sensory and motor

    • 2 divisons of sensory: general and special

    • 2 divisons of motor: SNS (somatic- skeletal muscle) and ANS (autonomic-cardiac m, smooth m, glands)

      • ANS is divided into sympathetic (tells structures what to do in emergency) and parasympathetic (tells structures what to do when resting)

        no neural cell bodies in nerves

Myelin factors

  • no myelin, unmyelinated

  • myeilnated, by oligodendrocytes

    • axon is myelinated by oligodendrocytes

  • myelinated, by Schwann cells

  • unmyelinated, but associated w Schwann cells

Organs of the PNS

Ganglia (2 kinds)

  • sensory: sensory neuron cell bodies & satellite cells

  • autonomic: postganglionic autonomic (neuron cell bodies)

Nerves (2 kinds: cranial and spinal): all spinal nerves are mixes, have sensory & motor fibers

  • nerves have CT

  • endoneurim around nerve fiber: aerolar CT, covers individiual neural fibers (may be myelinated)

  • perineurium around fascicles- covers facicles

  • epineurium around entire nerve- fibrous CT outside nerve

Synapse: a gap btwn a sensory receptor and a neuron

  1. sensory receptior (axon terminal)

  2. synaptic cleft (very tiny can only see thru microscope)

  3. post synaptic membrane (what the synaptic cleft touches) (transmitters are released)

sympathetic gangilia:

parasympathetic gangilia: usually in the wall of the target organ

epidural space- has adipose fat

Spinal Cord:

characteristics

  • connects brain to periphery(sensory receptors & effectors)

  • is located in vertebral column (for protection)

Anatomy

  1. Spinal Meninges (protection & coverings)
    meninges= CT coverings that encircle brain & spinal cord

  • pla mater (inner) delicate CT w collagen, vascular, closely adheres to brain & spinal cord, but there’s a subpial space

  • Arachnoid (middle) collagen & elastic fibers; trabeculae attach arachnoid to pia mater; subarachnoid space contains CSF

  • Dura mater (outer) dense fibrous CT

  1. external antomy of spinal cord

    • cauda equina (tail)

    • conus medularis

    • terminal filament of pia

    • terminal filament of dura

  2. internal anatomy

    (in spinal cord gray matter is inside, white is outside)

    (gray matter forms horns)

  • horns (grey matter) have different neuron cell bodies

    • posterior horn

    • lateral horn

    • anterior horn

    • tract

    • nerve

plexus=network

Functions of spinal cord

  • “information highway”

  • integration-reflexes: simple, complex; somatic, autonomic