02-NEUROLOGICAL PROCESS- Part 2

1\. Gathers information from both inside and outside the body - **Sensory Function**

2\. Transmits information to the processing areas of the brain and spine

3\. Processes the information in the brain and spine – **Integration Function**

4\. Sends information to the muscles, glands, and organs so they can respond appropriately – **Motor**

Functions of the Nervous System

It controls and coordinates all essential functions of the body including all other body systems allowing the body to maintain homeostasis or its delicate balance.

Nervous system

Central Nervous System (CNS) and the Peripheral Nervous System (PNS)

The Nervous System is divided into Two Main Divisions:

Neuron

Basic functional cell of nervous system

Neuron; 250 mph

The - transmits impulses (up to - mph)

Dendrite

Cell body with nucleus

Axon

Scwann cells

Myelin sheaths

Node of Ranvier

Parts of a neuron:

Dendrite

receive stimulus and carries it impulses toward the cell body 

Cell body with nucleus

nucleus and most of cytoplasm

Axon

fiber which carries impulses away from cell body 

Schwann cells

cells which produce myelin or fat layer in the Peripheral Nervous System 

Myelin sheaths

dense lipid layer which insulates the axon – makes the axon look gray 

Node of Ranvier

gaps or nodes in the myelin sheath 

dendrite; cell body; axon

Impulses travel from - to - to - 

Sensory neurons

Motor neurons

Interneurons

Three types of neurons

Sensory neurons

bring messages to CNS 

Motor neurons

carry messages from CNS 

Interneurons

between sensory & motor neurons in the CNS 

stimulus

A - is a change in the environment with sufficient strength to initiate a response. 

Excitability

is the ability of a neuron to respond to the stimulus and convert it into a nerve impulse 

All or nothing rule

The stimulus is either strong enough to start and impulse or nothing happens 

Impulses; from dendrite to cell body to axon 

are always the same strength along a given neuron and they are self-propagation – once it starts it continues to the end of the neuron in only one direction (-) 

nerve impulse

The - causes a movement of ions across the cell membrane of the nerve cell 

Synapse

small gap or space between the axon of one neuron and the dendrite of another – the neurons do not actually tough at the - 

Synapse

It is the junction between neurons which uses neurotransmitters to start the impulse in the second neuron or an effector (muscle or gland) 

synapse

The - ensures one-way transmission of impulses 

Neurotransmitters

Chemicals in the junction which allow impulses to be started in the second neuron 

A. Receptor

B. Afferent pathway (sensory neuron)

C. Interneuron

D. Efferent pathway (motor neuron)

E. Effector

Components of a Reflex Arc

Receptor (reflex arc)

reacts to a stimuli

Afferent pathway (sensory neuron)

conducts impulses to the CNS

Interneuron

consists of one or more synapses in the CNS (most are in the spine) 

Efferent pathway (motor neuron)

conducts impulses from CNS to effector. 

Effector

muscle fibers (as in the Hamstring muscle) or glands responds by contracting or secreting a product. 

Spinal reflexes

initiated and completed at the spinal cord level. Occur without the involvement of higher brain centers. 

Brain

* brain stem- medulla, pons, midbrain
* Diencephalon- thalamus & hypothalamus
* Cerebellum
* Cerebrum

Spine

* Spinal cord

Central nervous system:

Meninges

are the three coverings around the brain & spine and help cushion, protect, and nourish the brain and spinal cord. 

Dura mater

is the most outer , tough layer of the meninges

Arachnoid mater; pia mater

is the middle layer and adheres to the dura mater and has weblike attachments to the innermost layer, the -

Pia mater

is very thin, transparent, but tough, and covers the entire brain, following it into all its crevices (sulci) and spinal cord 

Cerebrospinal fluid

which buffers, nourishes, and detoxifies the brain and spinal cord, flows through the subarachnoid space, between the arachnoid mater and the pia mater 

Cerebellum

Cerebrum

Thalamus

Medulla

Brainstem

Hypothalamus

Regions of the brain

Cerebellum

coordination of movement and aspects of motor learning 

Cerebrum

conscious activity including perception, emotion, thought, and planning 

Thalamus

Brain’s switchboard – filters and then relays information to various brain regions 

Medulla

vital reflexes as heart beat and respiration 

Brainstem

medulla, pons, and midbrain (involuntary responses) and relays information from spine to upper brain 

Hypothalamus

involved in regulating activities internal organs, monitoring information from the autonomic nervous system, controlling the pituitary gland and its hormones, and regulating sleep and appetite 

Cerebrum

Is the largest portion of the brain encompasses about two-thirds of the brain mass 

Cerebrum; corpus callosum 

\- consists of two hemispheres divided by a fissure –

cerebral cortex, the medullary body, and basal ganglia 

Cerebrum includes:

Cerebral cortex; gray matter

is the layer of the brain often referred to as - because it has cell bodies and synapses but no myelin 

cerebral cortex

The - (thin layer of tissue) is gray because nerves in this area lack the insulation or white fatty myelin sheath that makes most other parts of the brain appear to be white.

cerebral cortex; 1.5mm to 5mm

The - covers the outer portion (-mm to -mm) of the cerebrum and cerebellum 

cerebral cortex; gyri; sulci

The - consists of folded bulges called - that create deep furrows or fissures called - 

cerebral cortex

The folds in the brain add to its surface area which increases the amount of gray matter and the quantity of information that can be processed 

Medullary body

is the white matter of the cerebrum and consists of myelinated axons 

Commisural fibers

Projection fibers

Association fibers

Fibers of the medullary body

Commisural fibers

pconduct impulses between the hemispheres and form corpus callosum 

Projection fibers

conduct impulse in and out of the cerebral hemispheres 

Association fibers

conduct impulses within the hemispheres

Basal ganglia

masses of gray matter in each hemisphere which are involved in the control of voluntary muscle movements 

Frontal lobe

motor area involved in movement and in planning & coordinating behavior 

Parietal lobe

sensory processing, attention, and language 

Temporal lobe

auditory perception, speech, and complex visual perceptions 

Occipital lobe

\
visual center – plays a role in processing visual information 

Broca’s area

Wernicke’s area

Limbic system

Special regions of the cerebrum

Broca’s area

located in the frontal lobe – important in the production of speech 

Wernicke’s area

comprehension of language and the production of meaningful speech 

Limbic system; aamygdala, hippocampus, septum, basal ganglia, and others

a group of brain structures (-) that help regulate the expression of emotions and emotional memory

Brain waves; electroencephalogram (EEG)

is are rhythmic fluctuation of electric potential between parts of the brain as seen on an -

electrodes; EEG

To measure brain waves - are placed onto the scalp using the -. 

Beta 

Alpha 

Theta 

Delta 

Four types of brainwaves

cranial nerves

12 pairs

Attached to undersurface of brain 

Spinal nerves

31 pair 

Attached to spinal cord 

Somatic nervous system (voluntary)

Relays information from skin, sense organs & skeletal muscles to CNS 

Somatic nervous system (voluntary)

Brings responses back to skeletal muscles for voluntary responses 

Autonomic Nervous System (involuntary) 

Regulates bodies involuntary responses; Relays information to internal organs

Sympathetic nervous system

in times of stress; emergency response; fight or flight 

Parasympathetic nervous system

when body is at rest or with normal functions; normal everyday conditions 

outer layer

consists of sclera and cornea 

middle layer

consists of choroid, ciliary body and iris 

inner layer

consists of retina

sclera or scleroid layer

(white of eye) a tough protective layer of connective tissue that helps maintain the shape of the eye and provides an attachment for the muscles that move the eye 

Cornea

the clear, dome-shaped part of the sclera covering the front of the eye through which light enters the eye 

Anterior chamber

a small chamber between the cornea and the pupil 

Aqueous humor

the clear fluid that fills that anterior chamber of the eye and helps to maintain the shape of the cornea providing most of the nutrients for the lens and the cornea and involved in waste management in the front of the eye 

Choroid layer

middle layer of the eye containing may blood vessels 

Ciliary body; iris

is a circular band of muscle that is connected and sits immediately behind the - which produces aqueous humor, changes shape of lens for focusing,

iris

the pigmented front portion of the choroid layer and contains the blood vessels 

iris

it determines the eye color and it controls the amount of light that enters the eye by changing the size of the pupil (an albino only has the blood vessels – not pigment so it appears red or pink because of the blood vessels) 

lens

a crystalline structure located just behind the iris - it focuses light onto the retina 

pupil

the opening in the center of the iris- it changes size as the amount of light changes (the more light, the smaller the hole) 

vitreous; vitreous humor

a thick, transparent liquid that fills the center of the eye; is mostly water and gives the eye its form and shape (also called the -)

retine

sensory tissue that lines the back of the eye

retina

it contains millions of photoreceptors (rods for black & white and cones for color ) that convert light rays into electrical impulses that are relayed to the brain via the optic nerve 

optic nerve

the nerve that transmits electrical impulses from the retina to the brain 

myopia or nearsightedness

where the eyeball is too long or the cornea is too steep

hyperopia or far sightedness

where the eyeball is short or lens cannot become round enough

cataracts

where the lens becomes fogged

presbyopia

where the muscles controlling the bulging of the lens become weak as we age 

Nyctalopia or night blindness

where vision is impaired in dim light and in the dark due to pigment rhodospin in the rods not functioning properly