Chapter 8 Nervous System

1. Receiving Sensory Input
2. Integrating information
3. Controlling muscles and glands
4. Maintaining homeostasis
5. Establishing and maintaining mental activity

Functions of the Nervous System

1. Central Nervous System
2. Peripheral Nervous System

What are the division of Nervous System

Central Nervous System

Consists of the brain and spinal cord

Peripheral Nervous System

Consists of all the nervous tissue, nerves and ganglia

1. sensory division
2. motor division

Two parts of the PNS

Afferent Division

Sensory Division is also called as?

Efferent Division

Motor Division is also called as?

Sensory Neurons

Neurons that transmit action potential from the PNS to the CNS are called?

Motor Neurons

Neurons that transmit action potential from the CNS to effector organs such as muscles and glands are called?

1. somatic nervous system
2. autonomic nervous system

Components of motor division

Somatic Nervous System

Transmit action potential from the CNS to skeletal muscles

Autonomic Nervous System

Transmit action potential from the CNS to cardiac, smooth muscle and glands

Enteric Nervous System

Uniques part of nervous system; has both sensory and motor neurons contained wholly within the digestive tract

Enteric Nervous System

Can function without input from CNS or other part of PNS; integrated with the CNS by sensory and ANS motor neurons

Neurons and Glial Cells

Types of Cells that make up Nervous System

Neurons

A cell that receive stimuli, conduct action potential and transmit signals to other ___ or effector organs

1. Cell body
2. Dendrites
3. Axons

Three Part of Neurons

cell body

part of the neuron that contains single nucleus

Axon

A single long cell process extending from the neuron cell body

axon hillock

the area where axon leaves the neuron cell body

collateral axons

branch axon is called?

Myelin Sheath

axons can be surrounded by highly specialized insulating layer of cells called?

1. Multipolar neurons
2. Bipolar neurons
3. Pseudo-unipolar neurons

Types of Neurons

Glial Cells

Supportive cells of the CNS and PNS; do not conduct action potentials; carry out different activities that enhance neuron function and maintain normal conditions within nervous tissue

1. Astrocytes
2. Epenmydal
3. Microglia
4. Oligodendrocytes

CNS glial cells are?

1. Satellite Cells
2. Schwann Cells

PNS glial cells are?

Astrocytes

Glial cell that serves as the major supporting cell in the CNS; contribute to blood-brain barrier ; help with neural tissue repair

Ependymal

line the fluid-filled cavities (ventricles of brain and central canal of spinal cord); circulate cerebrospinal fluid

Microglia

act as immune cells of the CNS; help protect the brain by removing bacteria and cell debris

Oligodendrocytes

provide an insulating material that surrounds axons

Schwann

in the PNS that provide an insulating material that surrounds axons

Satellite

found around the cell bodies of certain neurons of PNS; provide support and nutrition to neurons to protect from heavy-metal poisons

Myelin Sheaths

specialized layers that wraps around the axons of some neurons; are formed by oligodendrocytes and schwann cells

Myelinated Axons

Axons with myelin sheaths are called?

Unmyelinated Axons

Axons that lack myelin sheaths are called?

nodes of Ranvier

Gaps in the myelin sheaths are called?

Gray Matter

consists of groups of neuron cell bodies and their dendrites; very little myelin

cortex

Gray mater on the surface of the brain is called?

nuclei

cluster of gray matter located deeper within the brain are called?

ganglion

a cluster of neuron cell bodies (gray matter) in PNS is called?

White Matter

consists of bundles of parallel axons with their myelin sheaths

nerve tracts

white matter of the CNS forms?

nerve tracts

formed by white matter that propagate action potentials from one area of the CNS to another

nerves

white matter of PNS consists of bundles of axons and associated connective tissue forms?

voltage-gated channel

a channel that opened by a change in the electrical property of the cell membrane

chemically gated channels

a channel that opened by specific chemicals

leak channels

are always open channels, ions can cross the membrane, down with their concentration gradient

gated channels

channels that are closed until opened by specific signals

local current

movement of Na+ is called?

local potential

depolarization results in?

action potential

depolarization and repolarization constitute to?

hyperpolarization

cell membrane becomes more negative than the resting membrane potential, this condition is called?

continuous conduction

the pattern of action potential conducted slowly in unmyelinated axon, which conduction occurs?

Saltatory Conduction

the pattern of action potential conducted faster because of the jump on the node of Ranvier in myelinated axon, which conduction occurs? 

synapse

a junction where the axon of one neuron interacts with another neuron or cell of an effector organs

presynaptic terminal

in the synapse the end of the axon forms?

postsynaptic membrane

in the synapse the membrane of the dendrite of effector cell is?

synaptic cleft

space separating presynaptic and postsynaptic membrane is called?

neurotransmitters

chemical substances in the synaptic vesicles are called?

1. Acetylcholine
2. Norepinephrine

best known neurotransmitters?

1. Converging Pathway
2. Diverging Pathway

Two neuronal pathways?

converging pathway

two or more neurons synapse with the same postsynaptic neuron

diverging pathway

axon from one neuron divides the synapses with more than one other postsynaptic neuron

summation

many presynaptic action potentials are need, this process is called?

Spatial summation

type of summation that occurs when local potentials originate from different location of the postsynaptic neuron

Temporal summation

type of summation where local potentials overlap in time

Spinal Cord

extends from foramen magnum to 2nd lumbar vertebrae

cauda equina

resemble a horse’s tail; inferior end of the spinal cord

1. Dorsal Column
2. Lateral Column
3. Ventral Column

White matter of the spinal cord parts?

1. Ascending Tracts
2. Descending Tracts

consists of axon that conduct action potential; pathways in the spinal cord

Ascending Tract

consist of axon that conduct action potential TOWARDS the brain

Descending Tract

consist of axon that conduct action potential AWAY the brain

1. Dorsal horn
2. Lateral horn
3. Ventral horn

gray matter of the spinal cord part?

central canal

fluid-filled space in the center of the spinal cord

reflex

involuntary reaction in response to a stimulus applied to the periphery and transmitted to the CNS

Reflex arc

neuronal pathway by which a reflex occurs; functional unit of nervous system

1. sensory receptor
2. sensory neuron
3. interneurons
4. motor neuron
5. effector organ

Components of reflex arc

stretch reflex

simplest reflex; occurs when muscles contract in response to a stretching force applied to them

withdrawal reflex

is to remove a limb or another body part from a painful stimulus

1. Cervical
2. Throracic
3. Lumbar
4. Sacral
5. Coccygeal

Regions of Spinal Nerves

31

Total pairs of spinal nerves

mixed nerves

spinal nerves that contains both sensory and somatic motor neurons

dermatome

is the area of the skin supplied with sensory innervation by a pair of spinal nerves

1. Cervical Plexus
2. Brachial Plexus
3. Lumbosacral Plexus

Three major plexuses of the spinal nerves

C1 to C4

spinal nerves in the cervical plexus

phrenic nerve

most important branch of cervical plexus; innervates diaphragm

C5 to T1

spinal nerves in the brachial plexus

axillary nerve

innervates two shoulder muscles and the skin over part of the shoulder; brachial plexus

radial nerve

lies close to the medial side of the humerus; innervates all the muscles in the posterior arm & forearm as well as the skin over the posterior surface of the arm, forearm, & hand

Musculocutaneous Nerve

innervates the anterior muscles of the arm & the skin over the radial surface of the forearm

Ulnar Nerve

innervates two anterior forearm muscles & most of the intrinsic hand muscles & skin over the ulnar side of the hand

Median nerve

innervates most anterior forearm muscles & some of the intrinsic hand muscles & over the radial side of the hand

L1 to S4

spinal nerves in the lumbosacral plexus

1. Axillary Nerve
2. Radial Nerve
3. Musculocutaneous Nerve
4. Ulnar Nerve
5. Median Nerve

Five Major Nerves in Brachial Plexus

1. Obturator Nerve
2. Femoral Nerve
3. Tibial Nerve
4. Common Fibular Nerve

Four Major Nerves in Lumbosacral Plexus

Obturator Nerve

innervates the muscles of the medial thigh & the skin over the same region

Femoral Nerve

innervates the muscles of the medial thigh & the skin over the same region

Tibial Nerve

innervates the posterior thigh muscles, the anterior & posterior leg muscles, & most of the intrinsic foot muscles

also innervates the skin over the sole of the foot.

Common Fibular Nerve

innervates the muscles of the lateral thigh & leg & some intrinsic foot muscles

also innervates the skin over the anterior & lateral leg & the dorsal surface of the foot.

sciatic nerve

tibial and common fibular nerve bound together within a connective tissue