Chapter 7 The Nervous System

The Nervous System

A&P

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Body

Objectives

• Describe how Phineas Gage contributed to our current understanding of the brain.
• Compare and contrast the CNS v. PNS
• Identify & describe the functions the major regions of the brain & the specific structures/subregions within them.
• Describe how the CNS is protected.
• Compare/contrast the divisions and subdivisions of the PNS
• Identify and describe the major parts of a typical neuron
• Explain the steps of action potential.
• Explain how impulses are transmitted between neurons or between a neuron and effector.
• Define what a reflex is.
• Compare and contrast somatic v. autonomic reflexes.
• Describe major neurological disorders - medical name, signs/symptoms, potential complications, treatment/prevention

Vocab

• Sensory division
• motor division
• somatic nervous system
• autonomic nervous system
• sympathetic nervous system
• parasympathetic nervous system
• neuron
• soma
• dendrite
• axon
• myelin sheath
• oligodendrocytes
• schwann cells
• nodes of ranvier

• Central nervous system
• gyrus
• sulcus
• fissure
• hemisphere
• cerebrum
• cerebellum
• brain stem
• diencephalon
• thalamus
• hypothalamus
• limbic system
• fronta l lobe
• parietal lobe

• temporal lobe
• occipital lobe
• motor cortex
• broca's area
• somatosensory cortex
• wernicke's area
• gustatory cortex
• amygdala
• olfactory cortex
• auditory cortex
• visual cortex
• spinal cord
• cauda equina
• meninges
• cerebrospinal fluid
• peripheral nervous system

• axon terminal
• impulse
• action potential
• voltage gated channel
• stimulus gated channel
• synapse
• neurotransmitter
• neurotransmission
• reflex
• somatic reflex
• autonomic reflex
• cerebrovascular accident
• hemmorhagic stroke

Vocab

• ischemic stroke
• paralysis
• hemiplegia
• paraplegia
• quadriplegia
• monoplegia
• alzheimer's disease
• epilepsy
• generalized epilepsy
• focal seizure
• -itis
• meningitis
• encephalitis

Divisions of the Nervous System

Central Nervous System (CNS)

Central Nervous System (CNS)

• Brain
• Spinal cord
• Receives sensory input info
• Integrates info & generates output info

The Brain

Whiteboard Brain Dump: What do you know about the brain?

How do you think the size and shape of a human brain compares to a rat, chimp, and monkey?

Which brain belongs to who?

Parts of the Brain

Although all parts of the brain are interconnected and work together, different regions of the brain are "activated" during a variety of tasks.

How can we tell which parts of the brain are involved in certain tasks?

brain scans!

Scanning the Brain

What are some machines/techniques used by researchers to find out about the activity taking place inside someone's brain?

MRI, CT Scans, EEG, MEG, PET

Research & Report

• In your group, research your assigned brain scanning technique. When researching, you should be able to answer & explain the following:
• How it works
• Information it provides
• Advantages
• Disadvantages/drawbacks

When you have researched this information, write a summary on the table on the board. You will also send at least one representative up to discuss it with the class.

Phineas Gage

Brain Anatomy - General Terms

• Gyrus

• Sulcus

• Fissure

• Left vs. right hemisphere

Brain Anatomy - Major Regions

• Cerebrum

• Cerebellum

• Brain Stem

• Limbic System

Lobes of Cerebrum

• Frontal

• Parietal

• Temporal

• Occipital

Frontal Lobe

Functions:

• working memory, judgment, problem solving, language comprehension

Notable structures:

• Motor Cortex

• Broca’s area

• Olfactory bulb

Parietal Lobe

Functions:

• Processes sensory information (touch, temperature, & pain).
• It uses that sensory information to help with spatial orientation.

Notable Structure:

• Somatosensory cortex

Temporal Lobe

Functions:

• Processes auditory stimuli
• Processes taste
• Involved in language comprehension

Notable Structures:

• Auditory cortex

• Gustatory Cortex

• Wernicke’s area

Occipital Lobe

Functions:

• receives, processes, and interprets visual information

Notable structures

• Visual Cortex

Limbic System

Functions:

• fear processing
• long-term memory
• Information relay
• Control of endocrine system

Notable Structures:

• Thalamus

• Hypothalamus

• Hippocampus

• Amygdala

Spinal Cord

Structure:

• Starts at base of brainstem
• Extends to L1

Function:

• transports nerve impulses to and from brain.

Related Structure:

• Cauda equina

Protection of Brain & Spinal Cord

• meninges

• skull/vertebrae

• cerebro-spinal fluid (CSF)

Peripheral Nervous System (PNS)

Peripheral Nervous System (PNS)

• Nerves that branch out from brain and spinal cord

Functions:

• Senses stimuli
• Generates input info & sends to CNS
• Carries output from CNS to effector

Divisions of PNS

Sensory v. Motor Division

Sensory Division

Motor Division

• Includes all sensory (afferent) nerves.

• Receive sensory stimuli and deliver that information to the brain.

• Includes all motor (efferent) nerves.

• Receive information from the brain and deliver that information to the effector (generally a muscle or gland)

Subdivisions of Motor Nervous System

Subdivisions of Motor Nervous System

Somatic

Autonomic

• Controls involuntary responses (4F's)
• Includes nerves that go to smooth muscle (muscle of digestive system, urinary system, reproductive system) and cardiac muscle (muscles of the heart), as well as glands (produce hormones and other substances).

• Controls voluntary responses
• includes nerves that go to skeletal muscle (muscles attached to the skeleton that move the body).

Subdivisions of Autonomic Nervous System

Subdivisions of Autonomic Nervous System

Sympathetic

Parasympathetic

Fight or flight response

Rest and Digest response

Neurons

Types of Neurons

Neuron Anatomy

• Soma
• Nucleus
• Dendrite
• Axon
• Myelin Sheath
• Oligodendrocytes
• Schwann cells
• Nodes of Ranvier
• Axon Terminals

Nerve Impulses & Action Potential

Nerve Impulses & Action Potential

Basic Overview

• At rest, a neuron has a high concentration of ______ outside of the cell and a high concentration of _____ inside of the cell.

• When a stimulus “excites” a neuron, it generates an ___________ _______________ down the axon.

• Once the action potential reaches the axon terminals, ____________________ are released to send the impulse to another neuron, muscle, or gland

Question: How does the impulse travel across the synapse (area between nerve & target)?

Answer: it doesn’t! But neurotransmitters do!

• When the action potential reaches the axon terminal, _______________ channels open and calcium _______________ the axon terminal.
• This causes ________________ vesicles containing __________________ to travel to the end of the axon terminal and release their neurotransmitters into the _____________________ __________________.
• Neurotransmitters will then bind to a ___________________ on the next neuron which triggers an __________________ __________________ in that neuron. This process continues until the impulse reaches it's final target.

Put it all together - Action Potential and Neurotransmission

Reflexes

• Rapid, involuntary, pre-programmed response to a stimulus - bypasses the brain

Somatic v. Autonomic Reflexes

Neurological Disorders

Stroke

2 Types:

• Hemorrhagic - blood vessel ruptures in brain - prevents oxygen from reaching part of brain

• Ischemic - clot develops in blood vessel in brain - prevents oxygen from reaching part of brain

• Medical name: Cerebrovascular Accident (CVA)

Paralysis

Generally caused by a stroke or injury to the spinal cord 4 Major Types of Paralysis

• Hemiplegia - 1/2 of body (right or left) is paralyzed
• Paraplegia - 1/2 of body (usually lower limbs) is paralyzed
• Quadriplegia - paralysis from neck down
• Monoplegia - 1 limb is paralyzed

Alzheimer’s Disease

Signs/Symptoms:

• memory loss that disrupts daily life
• poor decision making
• disorientation to time/place
• language comprehension issues

• Most common cause of dementia (impaired ability to remember, think, make decisions)
• Exact cause is not well understood, but it is characterized by an accumulation of abnormally, misfolded proteins called amyloid & tau proteins.

Epilepsy - AKA Seizure Disorder

Seizures -a sudden, uncontrolled burst of electrical activity in the brain

Generalized Epilepsy

• Seizure that affects most of the brain at the same time

Focal Seizure

• Seizure activity in 1 specific area of brain

Meningitis & Encephalitis

-itis = inflammation Both of these diseases are typically caused by an infection

Both can be deadly if not treated quickly

Inflammation of meninges

• severe headache
• neck pain
• fever
• light sensitivity
• seizures

Inflammation of brain

• flu-like symptoms
• confusion
• halucinations
• weakness & loss of sensation
• seizures

Soma

• cell body
• contains nucleus and all other organelles

Broca's area

• Location: generally found on the left hemisphere of the frontal lobe.
• Function: coordinates muscles needed to form speech

Interneurons

• Found only in the CNS
• They interpret the message received from sensory neurons and send the interpretation to motor neurons.

Action Potential

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Meninges

Strong membranes that surround the brain and spinal cord Functions:

• anchors brain in place
• protection against infection

Hippocampus

where most long-term memories are formed & stored

Thalamus

Acts as the brain's "switchboard."

• Receives input from peripheral nerves and "decides" where the signal needs to go in the brain to be processed.

Motor Cortex

• Location: posterior frontal lobe

• Funtion: controls voluntary movement and motor learning (muscle memory)

Olfactory Bulb

• Location: inferior portion of frontal lobe (right above nose)
• Function: perception of smell

Cauda equina

• Literally translates to "tail of the horse" because it is a tuft of peripheral nerves that extend from the base of the spinal cord.
• Innervates the pelvis/lower body.

Auditory Cortex

• processes sound

Sensory Neurons

• AKA: Afferent neuron
• Make up the sensory nerves (of the PNS)
• Deliver a message to the brain

Cerebellum

• Projects posteriorly under the occipital lobe of the cerebrum
• Involved in coordination and balance

Cerebrospinal Fluid

AKA - CSF Fluid found between the brain/spinal cord and the skull/vertebrae. Functions:

• Cushions the brain and spinal cord.
• helps deliver oxygen/nutrients to those structures.

Myelin Sheath

• Fatty, waxy coating found in segments along some axons (usually of motor neurons)
• Increases the rate of electrical impulses
• Insulates the axon

Limbic System

• Deep brain structures
• Involved in fear processing, long-term memory, information relay, and coordination of the endocrine system

Somatosensory Cortex

• Location: anterior portion of parietal lobe.
• Function: processes touch, temperature, pain, and proprioception (position of body)

Visual Cortex

• Location: posterior tip of occipital lobe
• Function: perception of sight

Dendrites

• Numerous extensions coming off of soma
• Receives signals from other neurons and transmits those towards the soma

Motor Neurons

• AKA: Efferent neuron
• Neurons that make up motor nerves (PNS)

• Deliver a message from the brain to the effector (muscle or gland that it innervates)

Hypothalamus

Region beneath the thalamus that serves as a connection between the nervous and endocrine system.

• Regulates hormone production
• Regulates body temperature
• Controls hunger/thirst signals

Brain Stem

• Structure at the base of the brain that connects the brain to the spinal cord
• Controls basic life functions (consciousness, breathing, heart rate, blood pressure)

Axon

• Single extension coming off of soma
• Sends signal away from the soma

Nucleus

• Contains DNA

Cerebrum

• Largest region of the brain
• Consists of 2 hemispheres connected by the corpus callosum
• Each hemisphere is further subdivided into 4 lobes
• Extremely developed in humans

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Wernicke's area

• Location: usually in the left hemisphere of the temporal lobe
• Function: language comprehension

Gustatory Cortex

• Location: where frontal and temporal lobes meet
• Function: perception of taste

Amygdala

processes emotions, especially fear