The Nervous system The nerve cell is the basic unit of communication in the vertebrate nervous system

The Nervous system

The nerve cell is the basic unit of communication in the vertebrate nervous system

Bio 130 Human Biology

Components of the Nervous System

Figure 11.1


Three Classes of neurons

The Neural circuit consists of Sensory neurons

receptor for stimulus Interneuron (CNS)

integrate signals Motor neuron

transfer signal to effector (muscle)


Types of Neurons in the Nervous System

Figure 11.2


Anatomy of a Neuron

Cell body: functional portion

Dendrites: short extensions that receive signals

Axon: long extension that transmits impulses


How does a neuron hold and move info?

A neuron at rest has a voltage difference across the plasma membrane called a resting voltage potential

An action potential (AP) is when this charge across the membrane is briefly switched

The action potential moves down the membrane at a rapid pace.

Ap can move faster over mylenated portions is called saltatory conduction


Myelinated Neuron

Figure 11.7a



Maintenance of the Resting Membrane Potential

Figure 11.3


Resting Membrane Potential, Graded Potentials, and an Action Potential

Figure 11.4


The Nerve Impulse Is a Bioelectrical Signal

The sodium-potassium pump uses ATP to transport sodium ions out and potassium ions in

The inside of a resting neuron has a negative charge relative to the outside

An action potential is a reversal and restoration of the charge difference across the membrane

The sodium-potassium pump restores the original distribution of ions Action potentials are all-or-none events A neuron cannot fire during the refractory period


How does a signal move from one neuron to another?

A synaptic cleft divides 2 neurons The AP will not move across the synaptic cleft Neuro transmitters are released by the signal

cell to the receiver cell Move by diffusion



Transfer of Information from Neuron to Target

Synaptic transmission: Release of neurotransmitter: graded potential achieved

Effects of neurotransmitter: Excitatory: depolarize postsynaptic cell Inhibitory: hyperpolarize postsynaptic cell

Role of postsynaptic neuron: integrate and process information


Types of chemical synapse

Acetylcholine: neuromuscular junctions, glands, brain and spinal cord

Norepinepherine: affects brain regions concerned with emotions, dreaming

From table 11.1


The nervous System


Paths of information flow

Signals between the brain and spinal cord move to the body regions by nerves

Sensory nerves move a signal towards the brain and spinal cord

Motor neurons move a signal from the brain or spinal cord to the body


Divisions of the nervous System

Central nervous system

CNS

Is the brain and spinal cord

Peripheral nervous system

PNS

all nerves that carry signals to and from the CNS


Parts of the PNS

Sensory Division carries info to the brain and spinal cord.

Motor Division carries info from the brain to the bodies effectors (things that do the work)


The Motor division of the PNS has 2 divisions

Somatic nerves relay commands to and from skeletal muscle

Voluntary control

Autonomic nerves send signals to and from smooth muscles

Involuntary control

Sympathetic Parasympathetic


The autonomic divisions

Parasympathetic

slow down the body activity when the body is not under stress

Rest and digest

Sympathetic

increase overall body activity during times of stress, excitement or danger

fight or flight response

hormone epinephrine

Fig 11.12


Sympathetic and Parasympathetic

Are Antagonistic Work towards the automatic, subconscious

maintenance of homeostasis.


Parts of CNS


Components of the CNS

Spinal cord 31 pair of spinal nerves Grey matter White matter Controls some reflex

actions like bladder emptying

Brain parts Hindbrain

medulla oblongata cerebellum pons

Midbrain Forebrain

cerebrum thalamus hypothalamus


Ventricles of the Brain and Circulation of Cerebrospinal Fluid

Figure 11.13


Brain: Major Divisions

Hindbrain: coordinates basic, automatic, vital functions

Medulla oblongata: controls automatic functions of internal organs

Cerebellum: coordinates basic movements Pons: aids flow of information Midbrain: coordinates muscles related to vision

and hearing


Brain: Processes and Acts on Information

Forebrain: receives and integrates information concerning emotions and conscious thought

Hypothalamus: helps regulate homeostasis Thalamus: receiving, processing, and transfer center Limbic system: neuronal pathways involved in emotions

and memory Cerebrum/cerebral cortex: higher functions


Sleep

Sleep center: reticular activating system (RAS)

Stages: based on electroencephalograms (EEGs): Stage 1: transitional, random small waves on

EEG Stage 2: skeletal muscles relax, little eye or body

movement, EEG shows sleep spindles


Sleep (cont.)

Stage 3: heart and respiration slower, EEG shows slow wave sleep

Stage 4: difficult to awaken, heart and respiration slowest, body temperature decreased

REM (rapid eye movement) sleep: dreaming, EEG same as awake


Limbic System: Emotions of Fear, Anger, Sorrow, Love

Figure 11.19


Memory: Storing and Retrieving Information

Short term: working memory, information from previous few hours

Long term: information from previous days to years


Other parts of the CNS

The two cerebral hemispheres communicate through the corpus collosum left verbal skills right nonverbal skills such as music math, abstract

Brain cavities and Canals cerebrospinal fluid surrounds and fills in cavities in the

brain Blood Brain barrier- controls what moves into the brain.

Will prevent infections.


Our state of consciousness

The CNS governs sleeping, dozing, daydreaming and full alertness

neurons of the reticular activating system RAS control the changing levels of consciousness by releasing serotonin.


Memory

Association is the linkage of information to structural and chemical changes

short term- few bits lasts a couple of hours

Long term- permanent and limitless

The most important info goes rapidly into long term storage

memory is stored in a form resistant to degradation

Possibly caused by changes in synapses.


Tips on studying

Concentrate on what you study. Minimize interference. Study takes time. Break material into smaller portions. Rephrase materials in your own words. Test yourself to see what you know.

Primary somatosensory and motor areas of cerebral cortex


Disorders of the nervous system

Trauma Infections Transmission and synaptic defects. Abnormal growth Headache Tumors Stroke


Psychoactive Drugs

Action: affects higher brain functions Psychological dependence: user craves the

feeling associated with the drug Tolerance: takes more of the substance to

achieve the same affect Addiction: the need to continue obtaining and

using a substance; no free choice Withdrawal: physical symptoms that occur upon

stopping the drug


Know what the parts of the brain do

Brain parts medulla oblongata cerebellum pons cerebrum thalamus hypothalamus




seratonin

Just a reminder to talk about drugs that interact with brain.


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The Nervous system The nerve cell is the basic unit of communication in the vertebrate nervous system