IUPUI BIOL-N261 Lec. Exam 4

Cental Nervous System

Consists of the brain and the spinal cord

Peripheral Nervous System

Consists of nerves and ganglia, all are nervous tissue structures external to the CNS

Afferent Divison

SENSORY impulses carried from sensory receptors through the PNS toward the CNS

Efferent Divison

MOTOR impulses are carried AWAY FROM the CNS through the PNS, to the EFFECTORS, which are muscles and glands

Subdivisons of Efferent Divison

Somatic Nervous System (SNS) - voluntary control over skeletal muscles

Autonomic Nervous System (ANS) - involuntary control over smooth, cardiac muscles, and glandular activity

Soma

Cell body of a neuron

Features of a neuron

Dendrite

Cell body (Soma)

Axon

Terminal boutons

Neuroglia in PNS

Satellite Cell

Schwann Cell

Neuroglia in CNS

Ependymal cells

Oligodendrocytes

Astrocytes

Microglia

Ganglia

Clusters of PNS neuron cell bodies

Nerves

Bundles of axons in the PNS

Vesicular Synapse

Chemical synapse that involves neurotransmitters

Nonvesicular Synapse

Electrical synapse that involves direct contact between cells

Satellite cell function

Surround the neuron cell bodies in ganglia; regulate oxygen and carbon dioxide, nutrient, and neurotransmitter levels around neurons in ganglia

Schwann cell function

Surround all axons in PNS; responsible for myelination of peripheral axons; participate in repair process after injury

Ependymal cell function

Line ventricles (brain) and central canal (spinal cord); assist in producing, circulating, and monitoring CSF

Oligodendrocyte cell function

Myelinate CNS axons; provide structural framework

Astrocyte cell function

Maintain BBB; provide structural support, regulate ion exchange, nutrient, dissolved gas concentrations; absorb / recycle neurotransmitters; form scar tissue after injury

Microbial cell function

Remove cell debris, wastes, and pathogens by phagocytosis

Simple 3-neuron reflex arcs are?

Sensory neurons - enter the spinal cord dorsally

Motor neurons - exit it ventrally

Interneurons - are confined to the CNS

What do the nerves in the PNS consist of?

The nerves consist of peripheral axons of the sensory and motor neurons

Gray matter in CNS

Consists of the CELL BODIES of motor neurons and interneurons; some short unmyelinated axons and dendrites; some neuroglia

Types of sensory inputs and motor outputs

SOMATIC - refers to the OUTER body

VISCERAL - refers to mainly the INNER body

GENERAL - widespread

SPECIAL - localized

BRACHIAL innervation - refers to the motor innervation of the pharyngeal (branchial) muscle

PROPRIOCEPTION - refers to a series of senses that monitor muscle stretch in tendons, and joints. This senses the position and movement of our body parts

Axon features

Axon Hillock

Axoplasm

Collaterals

Terminal Aborizations

Terminal Bouton

Axolemma

What is the AXON HILLOCK on the axon, and what purpose does it serve?

Specialized region of an axon, it connects the initial segment of the axon to the cell body

What is the AXOPLASM on the axon, and what purpose does it serve?

It is the cytoplasm of the axon, it contains numerous organelles

What are the Collaterals on the axon?

They're the side branches of an axon

What are TERMINAL ARBORIZATIONS?

A series of fine terminal extensions, which branch from the tip of the axon and end at synaptic terminals

What are TERMINAL BOUTONS?

The area where one neuron synapses on another

What is the AXOLEMMA?

It is the plasmalemma of an axon

What is the Nucleoplasm or Perikaryon?

The cytoplasm that surrounds the nucleus in the SOMA

What supportive bodies are in the Nucleoplasm or Perikaryon?

Neurofibrils

Neurotubules

Neurofilaments

Chromatophilic (Nissl) bodies

SYNAPSE

Functional junction between neurons.

It functions as a site for intercellular communication

Occurs on dendrites (AXODENDRITIC), the cell body (AXSOMATIC), or along axons (AXOAXONIC)

MULTIPOLAR NEURONS

Includes several dendrites and one axon

BIPOLAR NEURONS

Includes one dendrite and on axon

UNIPOLAR NEURONS

Contains one process

PSEUDOUNIPOLAR NEURON

The dendrite and axon are continuous at one side of the cell body

AXAXONIC NEURON

Contains no distinguishable axon

4 Basic parts of the brain

Cerebral Hemispheres (Cerebrum)

Diencephalon - located deep inside the brain

Brain Stem (Midbrain, Pons, Medulla)

Cerebellum

WHITE MATTER

Mostly myelinated AXONS (or fibers) of neurons

What are the 5 brain ventricles?

Lateral ventricles (x2)

Third ventricle

Cerebral aqueduct

Fourth ventricle

Choroid plexus

Gyri

Feature on the brain that look like twisted ridges of brain tissue

Sulci (Sulcus)

Feature on the brain that consists of the deep grooves on the surface

Fissures - what are they, what are the two, what do they represent?

Deepest grooves on the brain surface. These separate major portions of the brain

TRANSVERSE CEREBRAL FISSURE - separates the cerebrum for cerebellum inferiorly

LONGITUDINAL FISSURE - separates the right and left cerebral hemispheres

Five major lobes of the brain, and what sulcus are they separated by?

Frontal lobe - separated from parietal lobe by the CENTRAL SULCUS

Parietal lobe

Occipital lobe - separated from the parietal lobe by the PARIETO-OCCIPITAL SULCUS (occipital fissure)

Temporal lobe - separated from the parietal and frontal lobes by the LATERAL SULCUS (Sylvian Fissure); inferiorly separated from the occipital lobe by the CALCARINE SULCUS

Insular lobe

Cerebral Cortex

Site of conscious sensory perception, voluntary initiation of movements, higher thought functions

Contains billions of neurons arranged into SIX LAYERS

Brodmann Areas: 52 different areas

3 Functional Ares of the Cerebral Cortex

MOTOR

SENSORY

ASSOCIATED AREAS

EPINEURIUM

Tough fibrous connective sheath SURROUNDING A WHOLE NERVE, which consists of several fascicles and blood vessels

FASCICLES

Bundles of neuronal axons

PERINEURIUM

Connective tissue SURROUNDING EACH FASCICLE; forms the NERVE-BLOOD BARRIER

ENDONEURIUM

Delicate connective tissue fibers that SURROUND THE INDIVIDUAL AXONS OF FASCICLES

CNS is connected to the PNS via?

Cranial nerves and Spinal nerves

PNS Divisons

Sensory (AFFERENT)

Somatic

Visceral

Motor (EFFERRENT)

Somatic Motor

Branchial Motor

Visceral (ANS)

AUTONOMIC NERVOUS SYSTEM DIVISIONS

Parasympathetic - (Craniosacral) rest,digest

Sympathetic - (Thoracolumbar) fight or flight

Receptors in the PNS are classified by what?

They're classified by their stimuli, type of stimulus that transfer special senses information

DORSAL ROOT GANGLION

PNS ganglion containing the cell bodies of SENSORY neurons