Unit 2 Chapter 17: The Nervous System Biology 12

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Chapter 17 Notes: The Nervous System

Overview/Objectives: • 17.1- Nervous Tissue

o Two major divisions of the nervous system o Three parts of a neuron & classes of neurons o Action potential o Impulse transmission

• 17.2- The Central Nervous System (CNS) o Two structures that compose the CNS o Functions of the spinal cord o 4 major parts of the brain and their general functions

• 17.3- The Limbic System and Higher Mental Functions o Function of the limbic system o Structures involved in long term memory and language/speech

• 17.4- The Peripheral Nervous System o Cranial and spinal nerves o Reaction to stimulus o Autonomic system

• 17.5- Drug Abuse

Introduction: • Nervous system & Endocrine system = responsible for integration and control in the

body. • The __________________________ is capable of much more rapid and specific

responses than the endocrine system. 17.1- Nervous Tissue • Two major Divisions of the Nervous System:

1. ___________________________ = Brain and spinal cord (located in midline of body)

2. ___________________________ = Nerves that carry sensory messages to the CNS and motor commands from the CNS to the muscles and glands

The two systems are interconnected and work together

• The nervous system contains two types of cells:

1. ______________= transmit nerve impulses between parts of the nervous system

2. ______________= support & nourish neurons

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The Neuron: • The neuron is the basic cell of the nervous system. • Among the most highly specialized cells.

Structure: the neuron is divided into 3 distinct sections:

1. _____________= contains nucleus and coordinates cell activities 2. _____________= carry impulses to cell body 3. _____________= carry impulses away from cell body

• _____________ = fatty substance surrounding parts of the neuron

• _____________ = gapes where there is no myelin sheath

• _____________ = make the myelin sheath

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TYPE OF NEURON

DESCRIPTION FUNCTION

• contain special receptors to detect stimuli • Long myelinated dendrites • Short axons • Cell body outside the spinal cord contained in ganglion

Carry impulses toward the CNS

• entire neuron is found inside the spinal cord • your brain is made up of all interneurons

connect the sensory and motor neurons

• short dendrites • long myelinated axons • end of motor neurons are motor end

plates attached to muscles

Carry message from the brain and spinal cord to muscles and cells

Nerve Impulses: Conduction of the Nerve Impulse Nerve impulses rely on electrical charges which come about from the ionic charges of certain minerals in the body specifically _______________________________________ Terminology

• __________________= while the neuron is not being stimulated sodium remains outside while potassium is inside the neuron ( neuron is ______________ + outside the neuron and – inside due to large organic ions)

• __________________= are found along the neuron membrane (axomembrane) and allow ions to move in and out of the cell

• __________________= amount of stimulus required to cause the neuron to fire

• __________________= when the threshold is met sodium gates open and Na + rushes into cell causing a swing in polarity

• __________________=immediately following the rush of sodium into the cell potassium gate open and K+ rushes out to repolarize neuron

• __________________=refers to the movement of ions in and out of cell causing a nerve impulse

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• __________________=all neurons must go through a short rest period and redistribute ions in order to carry out another impulse

The Neuron:

• Along the inside of the membrane are _______________charge organic ions that can’t cross the membrane.

• The effect of this is that the inside is _____________ and the outside is _______________

• This produces a membrane potential of about __________ Action Potential:

1. When the impulse reaches any point along the axon, it causes “___________” to open and _______ floods in.

2. This is due to both a ________________________ and __________________________

3. This influx of positive ions repels ______ which leave as the “________________” open.

4. This ______________ the axon = nerve impulse.

5. ___________________ cause the sodium gates immediately adjacent and downstream

to open, ___________________ now occurs there.

6. This continues as a wave of depolarization along the entire length of the axon

_________________ (Recovery phase)

• As the wave of _______________ moves past, the sodium - potassium pump kicks in again pumping the ___________ and allowing the ______ to __________________

• This restores the resting potential and the axon can now fire again.

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• The impulse “jumps” from node to node _________________________________ under the myelin sheath.

• This is termed “_________________________” and greatly speeds up the impulse.

• Nerve conduction is “________________” - if the threshold stimulus is achieved, the impulse will go the entire length of the neuron.

_____________________

- In myelinated neurons only unmyelinated regions of the axon depolarize.

• Thus, the impulse moves faster than in unmyelinated neurons.

The Neural Synapse • The junction point between a nerve and any other structure is called a ___________

• Pre synaptic cell ends in synaptic knobs that connect to a post synaptic neuron.

• In between the two is a space called the ___________________

• In the synaptic knob are synaptic vesicles containing ____________________molecules.

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Conduction across the neural synapse:

1. When the impulse reaches the synaptic knob, ______ floods into the knob from the extra cellular environment.

2. This influx causes the synaptic vesicles to move to the presynaptic membrane and fuse to it.

3. This ruptures the ____________ and _________________ floods into the ________________

4. The neurotransmitter diffuses across the cleft and ___________________________ on the post synaptic membrane.

5. This opens the sodium gates that allows ___________________, initiating the nerve impulse in the second cell.

6. _______________quickly break down the attached neurotransmitter to end the transfer.

Neurotransmitters:

1. __________________: most common type - used in brain and in transmission to muscles.

2. __________________(noradrenaline): Function in the CNS and Autonomic nervous system - inter neuron communication.

3. ____________________: • Related neurotransmitters in brain - involved in sleep, moods, attention, and learning. • Dopamine inhibits pain.

4. ______________ (gamma aminobutyric acid): Acts inhibitory in the synapse - prevent transmission of message across synapse.

5.____________________: • Mostly NO and CO. • NO acts to relax smooth muscle around blood vessels thus causing them to dilate (ex.

Heart, penis). • Nitroglycerine, Viagra

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Organization of the Nervous System:

17.2- The Central Nervous System (CNS)

• Function: sensory information received and motor control initiated

• Consists of : ________________&_________________

– Both are protected by bone and _______________ (protective membrane)

– ____________________ (CSF) = fills the space between the meninges functions to cushion and protect

• CNS is composed of 2 types of nervous tissue:

1. ________________= contains cell bodies & short, nonmyelinated fibers

2. ________________= contains myelinated axons that run together in bundles = tracts

1.______________________

Structure:

• Extends from the base of the brain through a large opening in the skull (foramen magnum) vertebral canal (openings in the vertebrae)

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• ___________________= fluid filled cushion that separates the vertebrae

Function: • Provides communication between brain and peripheral nerves • Center for thousands of reflex arcs

The Reflex Arc: • Used to respond to emergencies. • Three types of neurons involved:

1. ___________________________: from sensory receptor to spinal cord.

2. ____________________________: connect spinal cord to muscles.

3. ____________________________: inside spinal cord, connect sensory neuron to motor neuron.

• Used as brain bypass when response is obvious.

2._____________________ __________________

• Largest part of the brain “higher” brain controls voluntary actions. • Is where we live!

Lobes of the Cerebrum:

1. _____________: motor area, concentration, planning, judgment, problem solving.

2. _____________: Sensory for touch and taste, speech and language centers.

3. _____________: Sensory for hearing and smell, memory and sensory interpretation.

4. _____________: Vision and integration of vision with other senses.

_________________ • part of the brain stem just above the spinal cord • Controls breathing and heart rate • Responsible for involuntary actions

_________________

• Coordinates and smoothes all motor functions. • Takes muscle commands from the cerebrum and ensures that all related muscles

contract in the correct sequence. • Also involved in learning and remembering motor responses.

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________________ • Two major functions

1) Accomodation: All sensory nerves go through the thalamus 2) It acts as a filter for the higher brain.

• Once the higher brain is aware of a stimulus, the thalamus will filter it out if it is not significant to the higher brain.

__________________

• We’ve already seen the endocrine role of this structure. • It contains centers for controlling most basic body needs; thirst, hunger, etc. Also can

trigger some very basic behaviors: rage, fear, sexual behavior, and pleasure. • This part of the hypothalamus is referred to as the Limbic System. • The hypothalamus, along with the pineal gland, also determine our circadian rhythms.

__________________

• Called the Master Gland as its hormone control most other glands (termed tropic hormones).

Contains two parts: 1. ___________________

• Stores and releases hormones produced in the hypothalamus. 2. ___________________

• Makes and releases its own hormones. • Releases them upon stimulation from hypothalamus • Hormones include: Growth hormones, Prolactin (causes lactation), FSH and LH

(reproductive), and ACTH (stimulates release of adrenalin). Hormones of Posterior Pituitary are:

• A. ___________: causes contraction of selected smooth muscles (uterus and milk ducts). • B. ______: effects the kidneys and allows the body to conserve water (more

concentrated urine). Lateralization of Brain Function: ______________________ Specializes in language, math, logic operations, and the processing of serial sequences of information, and visual and auditory details. Specializes in detailed activities required for motor control. ______________________ Specializes in pattern recognition, spatial relationships, nonverbal ideation, emotional processing, and the parallel processing of information.

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17.3- The Limbic System and Higher Mental Functions ____________________

• Intimately involved in our emotions and higher mental functions Emotions. • In mammals, the limbic system is composed of the hippocampus, olfactory cortex, inner

portions of the cortex’s lobes, and parts of the thalamus and hypothalamus. – Mediates basic emotions (fear, anger), involved in emotional bonding, establishes

emotional memory Higher Mental Functions: Memory and Learning

• ________________ memory stored in the frontal lobes.

• The establishment of ____________________ involves the hippocampus.

• The transfer of information from short-term to long-term memory. – Is enhanced by ___________ (remember that when you are preparing for an exam). – Influenced by ______________________ mediated by the amygdala. – Influenced by ____________ with previously stored information.

• Different types of long-term memories are stored in different regions of the brain. • __________________ memory can be rapid.

– Primarily involves changes in the strength of existing nerve connections. • _____________________________________ is slower.

– Appears to involve cellular mechanisms similar to those involved in brain growth and development.

Language and Speech

• Broca’s area= speaking (motor speech) • Wernicke’s area= understanding language (sensory speech) 17.4- The Peripheral Nervous System

• Outside of the CNS, composed of ___________ & ______________ • __________= bundle of axons (fibers)

– _______________ = carry info to CNS – _______________= carry info away from CNS

• _____________= swellings associated with nerves that contain collections of cell bodies

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____________________ = 12 pairs come directly off the brain • Some are sensory only (optic, auditory) rest are mixed. • Control head and upper neck. • Includes #10, the Vagus nerve, that forms part of the autonomic nervous system

A) Somatic System

• Serves the skin, skeletal muscles, and tendons • Includes nerves that:

– Take __________info from external sensory receptors ___CNS – Take _________________ ______from CNS to skeletal muscles

• Some actions due to ______________(automatic response to stimulus) • Other actions are _______________(originate in cerebral cortex)

B) Autonomic System

• Regulates the activity of cardiac and smooth muscle and glands • Made of two opposing divisions:

1. ______________________

2. ______________________ These two divisions have several features in common:

1. Function automatically and usually involuntary 2. Innervate all internal organ 3. Each signal two neurons that synapse at a ganglion

1. The Sympathetic Division • Derived from nerves which connect to a ganglionic chain from the thoracic and lumbar

regions of the spinal cord.

• _______________ to most organs (heart, breathing, blood pressure, pupils) but inhibitory to digestive system (parasympathetic)

• Prepares body for action “________________” 2. The Parasympathetic Division • Derived from nerves which connect to a ganglionic chain from the cranial and sacral regions

of the spinal cord. It is inhibitory to most organs (heart, breathing, blood pressure, pupils) but stimulates digestive and reproductive systems.

• Used during rest and is antagonistic to sympathetic system and returns systems to “normalcy”

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__________Pathway _____________ Pathway

Type of control Voluntary/Involuntary Involuntary Involuntary

#neurons per message

One Two (preganglionic short than postganglionic)

Two (preganglionic longer than postganglionic)

Location of motor fiber

Most cranial nerves & all spinal nerves

Thoracolumbar spinal nerves

Cranial and sacral spinal nerves

Neurotransmitter

Effectors Skeletal Muscles Smooth and cardiac muscle glands

Smooth and cardiac muscle glands

17.5- Drug Abuse List 5 common drugs that are commonly abused and how they affect the nervous system:

Drug Abused: Effect on Nervous System

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