PSYCHOLOGY: Chapter 6 - The Body and Behavior Lecture Notes

* Bold print denotes an item not in the text.

6-1: The Nervous System: The Basic Structure

Runner's high: the natural “second wind” an athlete gets when endorphins are secreted and produce euphoria.

Endorphin: neurotransmitter that inhibits pain.

2 points on the nervous system:

1.) The nervous system is never at rest. There is always a job for it to do.

2.) Even when you are sleeping the nervous system is busy regulating your body functions.

4 things the nervous system controls:

1.) emotions

2.) movements

3.) thinking

4.) behavior

2 parts of the nervous system:

1.) Central nervous system (CNS): Brain and spinal cord

2.) Peripheral nervous system (PNS): the nerves branching out from the spinal cord

3 points on the PNS:

1.) The nerves of the peripheral system conduct information from the bodily organs to the central nervous system and take information back to the organs.

2.) These nerves branch out from the spinal column.

3.) In size they are about as thick as a pencil (spinal nerves) to invisibly small (in the extremities).

Nerve fibers: These are what we call "nerves". These carry chemical-electrical messages from receptor cells to brain in 1/50 of a second.

* A-alpha nerve fibers: carry information related to proprioception (muscle sense).

* A-beta nerve fibers: carry information related to touch.

* A-delta nerve fibers: carry information related to pain and temperature.

* C-nerve fibers: carry information related to pain, temperature and itch.

Central nervous system: Powerhouse of the body made up of the brain and spinal cord.

Protection of the Nervous Systems:

4 types of protection:

1.) sheathing

2.) meninges

3.) vertebrae

4.) skull

Sheathing (myelin): A white, fatty substance that insulates and protects the axon for some neurons, and protects the brain and peripheral nerves.

Meninges: Series of 3 membranes that cover the brain and spinal cord.

- Dura mater, The outer layer of the meninges is called the dura mater or just the dura. The dura is a tough and thick fibrous

material.

- Arachnoid: The middle layer is called the arachnoid - A clear membrane with fine strands (resembles a spider's) that surrounds a cap

of cerebrospinal fluid that covers the surface of the entire central nervous system. Below the arachnoid lies the

subarachnoid space. The cerebral arteries run through the subarachnoid space. (The subarachnoid space is the space into

which aneurysms of the cerebral vessels hemorrhage.)

- Pia mater: The innermost of the three membranes (meninges) that surround the brain and spinal cord of vertebrates is called the pia

mater (or just the pia). The pia mater lies immediately adjacent to the central nervous system, and the choroids plexus,

which secretes cerebrospinal fluid, is an extension of it.

It's all kind of like the brain wrapped in Saran wrap, put in a sandwich bag, and then sealed in a Ziploc bag.

Vertebrae: The adult vertebral (spinal) column consists of 26 bones that are grouped as follows: (** See diagram in study guide)

- cervical vertebrae: #7 in the neck; numbered C-1 to C-7. C-1 and C-2 do not move.

- thoracic vertebrae: #12 that articulate with the 12 pairs of ribs; numbered T-1 to T-12. Some rotation can

occur between the thoracic vertebrae, but their connection with the rib cage prevents much

flexion.

- lumbar vertebrae: #5 of the lower back; numbered L-1 to L-5). These vertebrae are very robust in construction,

as they must support more weight than other vertebrae. They allow significant flexion and extension.

- sacrum: #1 which is actually a fusion of 5 sacral vertebrae. Fusion occurs from late teens to early 20's.

- coccyx or "tailbone": #1 which is a fusion of 4 coccygeal vertebrae

Intervertebral discs: located between adjacent vertebrae. These fibrocartilage discs form strong joints and absorb spinal compression shock.

Each disc allows slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.

* Disc degeneration: Over time, spinal discs dehydrate and become stiffer, causing the disc to be less able to adjust to compression.

While this is a natural aging process, in some individuals, as the disc degenerates it can become painful.

* Disc problems: Because of the way it is attached to the vertebra above and below it, a disc cannot “slip” as commonly thought. However,

trauma and injury to the spine can cause discs to bulge, be herniated or, even worse, rupture. This can be quite painful,

putting pressure on the spinal cord and nerve roots, interfering with function - and causing pain.

^ 3 common types:

1.) Disc Tear: The most common disc injury is a small crack or microtear in the tough, outer cartilage material of the disc

(called annular fibers). This allows the fluid to start leaking out, and the disc begins to wear thin.

2.) Bulging Disc: The soft jelly-like material in the middle of the disc pushes to one side, forward, or backward, and swelling

occurs. The nucleus is still contained within the tough outer fibers of the disc, but can still cause pressure and painful symptoms.

3.) Herniated Disc: The soft jelly-like material from the nucleus in the middle of the disc ruptures through the tough, outer fibers and extends to the outer edge or beyond

the normal limits of the disc.

Spinal cord: is about 45 cm (18 inches) long in men and 43 cm long in women. However, this is much shorter than the length of the bony spinal column. In fact, the spinal cord extends down to

only the last of the thoracic vertebrae. Therefore, nerves that branch from the spinal cord from the lumbar and sacral levels must run in the vertebral canal for some distance

before they exit the vertebral column.

* spinal nerves: 31 pairs of nerves that extend from the spinal cord outward to the body.

* cranial nerves: are 12 pairs of nerves that can be seen on the ventral (bottom) surface of the brain. Some of these nerves bring information from the sense organs to the brain;

other cranial nerves control muscles; other cranial nerves are connected to glands or internal organs.

Brain:

* contains three-fourths of the body's neurons about (100 billion neurons).

* weighs about 3 pounds (human head weighs 8-10) About 2%-3% of the human body weight.

Skull: There are 8 bones that surround your brain. These 8 bones make up the cranium. Another 14 bones in the face make up the entire skull. There is a large opening, called the

foramen magnum, located in the back of the occipital bone. This is where the medulla ends and projects out of the skull. Smaller holes in the skull, called foramina, allow nerves and

blood vessels to enter and leave the cranium.

- sutures: the places in the skull where the bones come together fused together. These sutures are flexible in young children, but become fixed as you age.

Paralysis: the loss of power of voluntary movement in a muscle through injury or through disease, or the loss of sensation over a region of the body, of its nerve supply. Paralyzed means one cannot move due to

a severed spinal cord.

Spinal Cord Injury Packet

Neurons: the long, thin cells that constitute the structural and functional unit of nerve tissue along which messages travel to and from the brain.

Brief points:

- the oldest and longest cells in the body. You have the same neurons for your whole life.

- the human brain has about 100 billion neurons.

- have specialized extensions called dendrites and axons.

- can flash, (burn) hundreds of times a minute, and normally don't burn out.

- new research says that these may regenerate in certain situations.

- how messages are transmitted: Chemical electrical signals travel down the neurons much as flame travels along a firecracker fuse. Transmission between neurons occurs whenever the cells

are stimulated past a minimum point and emit a signal.

- # of times a neuron can “burn”: the neuron can fire (burn) over and over again, hundreds of times a minute.

- "all-or-none" principle: when a neuron fires, it does so at full strength. If a neuron is not stimulated past the minimum, or threshold, level, it does not fire at all.

* comparative example: In an engine, the sparkplug ignites the gaseous vapor in an engine cylinder. The piston (within the engine) does nothing until the sparkplug fires, causing the

vapor to explode.

- 3 basic parts: the cell body, dendrites, and axons.

* cell body: contains the nucleus and produces the energy needed to fuel neuron activity.

* dendrites: (receiver) are short, thin fibers that stick out from the cell body, that receive impulses, or messages, from other neurons and send them to the cell body.

* axons: (sender) is a long fiber that carries the impulses away from the cell body toward the dendrites of the next neuron.

^ size: can be very short or several feet in length.

Differences between axons and dendrites

Axons Dendrites

Take information away from the cell body Bring information to the cell body

Smooth Surface Rough Surface (dendritic spines)

Generally only 1 axon per cell Usually many dendrites per cell

No ribosomes Have ribosomes

Can have myelin No myelin insulation

Branch further from the cell body Branch near the cell body

Neurons can be quite large - in some cases, like corticospinal neurons (from motor cortex to spinal cord) or primary afferent neurons (such as those extending from the skin into the spinal cord and up to the brainstem) can be several feet long!

- myelin sheath: A white, fatty substance that surrounds some neurons (neural tissue).

* 3 duties: Insulates and protects the axon, and speeds the transmission of impulses.

* Multiple Sclerosis: nervous system disease in which the myelin sheath is destroyed, and as a result, the behavior of the person is erratic and uncoordinated.

- axon terminals: branch out at the end of the axon; terminals are positioned opposite the dendrite of another neuron to receive impulses.

- Synapse: the gap that exists between individual nerve cells. It is a junction or connection between the neurons where the neuron transmits its impulses or message to another neuron.

* size: less that one millionth of an inch wide.

* contents: filled with fluid that transmits the chemicals from one neuron to another.

- Neurotransmitters: the chemicals released by neurons, which determine the rate at which other neurons fire. Neurotransmitters open chemical locks or excite the receptors.

* excite: making a neuron transmit.

* inhibition: stop a neuron from transmitting

* flow: in only one direction.

* examples:

^ Norepinephrine: A substance, both a hormone and neurotransmitter, secreted by the adrenal medulla and the nerve endings of the sympathetic nervous system to cause blood vessel constriction

and increases in heart rate, blood pressure, and the sugar level of the blood. This neurotransmitter is also involved with memory and learning.

^ Endorphin: neurotransmitter that inhibits pain. (and

kind of creates a euphoria.

* supply level differences: The oversupply or undersupply of

certain neurotransmitters has

been linked to certain diseases.

^ Acetylcholine: a neurotransmitter involved in

movement and memory. A decrease

in this neurotransmitter is

associated with paralysis and

Alzheimer’s disease.

+ Alzheimer's disease: currently an irreversible,

incurable condition that destroys a

person’s ability to think, remember,

relate to others, and care for her or

himself.

^ Dopamine: neurotransmitter involved in learning,

emotional arousal, and movement. An

oversupply of this neurotransmitter is

associated with schizophrenia, and an

undersupply associated with Parkinson's

disease.

+ Schizophrenia: a group of severe psychotic

disorders characterized by

confused and disconnected

thoughts, emotions, behavior,

and perceptions.

+ Parkinson's disease: A progressive nervous

disease occurring most often after the

age of 50, associated with the

destruction of brain cells that produce

dopamine, and characterized by

muscular tremor, slowing of movement,

partial facial paralysis, peculiarity of

gait and posture, and weakness.

^ Serotonin: a neurotransmitter involved in sleep,

depression, and memory. An undersupply

of norepinephrine and serotonin may

result in depression.

Types of Neurotransmitters Handout

- neuron activity: each neuron is either "on" or "off" depending

on the neural activity around it.

* intensity: The intensity of activity in each neuron

depends on how many other neurons are acting

on it.

- Neural impulse destination: The actual destination of

nerve impulses produced by an excited neuron, as

they travel from one neuron to another, is limited by

what tract in the nervous system they are on.

* ascending tracts: carry sensory impulses to the brain.

* descending tracts: carry motor impulses from the brain.

- 3 types of neurons:

* afferent: also called sensory neurons they relay messages

from the sense organs (including eye, ear, nose,

and skin) to the brain.

* efferent: also called motor neurons, they send signals

from the brain to the glands and muscles.

* interneurons: carry impulses between neurons in the body.

2 types of actions: and a nervous system for each.

1.) voluntary: what you choose to do like lifting your hand

2.) involuntary: happen automatically like heartbeat and

breathing

Somatic Nervous System (SNS): the part of the peripheral nervous

system that controls voluntary

movement of skeletal muscles.

(Soma is Latin for body.)

Autonomic Nervous System (ANS): the part of the peripheral nervous

system that controls internal

biological functions.

It should be noted that the autonomic nervous system is always working. It is not ONLY active during "fight or flight" or "rest and digest" situations. Rather, the autonomic nervous system acts to maintain normal internal functions and works with the somatic nervous system. The ANS regulates:

Muscles

in the skin (around hair follicles; smooth muscle)

around blood vessels (smooth muscle)

in the eye (the iris; smooth muscle)

in the stomach, intestines and bladder (smooth

muscle)

of the heart (cardiac muscle)

Glands

- 3 parts of the ANS: sympathetic, parasympathetic and enteric

nervous systems.

* Sympathetic nervous system: part of the ANS that

prepares the body for dealing with

emergencies or strenuous activity.

** This what kicks in your "fight or

flight" response.

^ 6 actions:

1.) It prepares the body for dealing with

emergencies or strenuous activity.

2.) It speeds up the heart to hasten the supply of

oxygen and nutrients to body tissues.

3.) It constricts some arteries and relaxes others

so that blood flows to the muscles, where it is

most needed in emergencies and strenuous

activity.

4.) It increases the blood pressure.

5.) It increases respiration.

6.) It suspends some activities (like digestion).

* Parasympathetic nervous system: works to conserve

energy and to enhance the body’s ability to

recover from strenuous activity.

- 4 actions:

1.) It works to conserve energy and to enhance the

body’s ability to recover from strenuous

activity.

2.) It reduces the heart rate.

3.) It reduces blood pressure.

4.) It works to bring the body back to its normal

resting state.

* Enteric nervous system: regulates the normal activity

of the digestive system and

prepare it for whatever its

future may hold.

- "autopilot": All of this takes place automatically. Receptors

are constantly receiving messages that alert the

autonomic nervous system to carry out routine

activities.

- without one's ANS: We would have to consciously think about

doing even the most basic of activities…

and that would include breathing!

6-2: Studying the Brain

Early Greeks: were not really impressed with the brain.

- brain's function: was to cool the blood.

- heart's function: was the source of feelings and thoughts.

- Hippocrates: Ancient Greek philosopher who is considered to

be the “father of medicine”, believed

somewhat differently than most. He believed

diseases were caused by natural, not

supernatural (evil spirits) causes.

* effect of brain injuries: observed the effect of head

injuries on people’s thoughts and

actions and noted,

* quote: “[F]rom the brain, and from the brain only, arise

our pleasures, joys, laughter and jests, as well as

our sorrows, pains, griefs and tears. Through it, in

particular, we think, see, hear. . . . Eyes, ears,

tongue, hands and feet act in accordance with the

discernment [judgment] of the brain.”

^ meaning: There is more going on in the brain than

what most Greeks thought.

3 main parts of the brain: hindbrain, midbrain, and forebrain.

- hindbrain: a part of the brain located at the rear base of the

skull that is involved in the basic processes of life

such as sleeping, waking, coordinating body

movements, and regulating vital reflexes.

* 3 parts: cerebellum, medulla, and the pons.

^ cerebellum: a part of the brain that helps control

posture, balance, and voluntary

movements.

^ medulla: part of the brain that controls breathing,

heart rate, and a variety of reflexes.

+ contents: contains the respiratory, vasomotor

and cardiac centers, as well as

many mechanisms for controlling

reflex activities such as coughing,

gagging, swallowing and vomiting

^ pons: functions as a bridge between the spinal cord

and the brain. It is also involved in producing

chemicals the body needs for sleep.

- midbrain: serves as the nerve pathway of the cerebral

hemispheres and contains auditory and visual reflex

centers.

* action: integrates sensory information and relays it

upward.

- Brainstem: The lower extension of the brain where it connects

to the spinal cord.

* 5 neurological functions located in the brainstem:

1.) breathing

2.) digestion

3.) heart rate

4.) blood pressure

5.) arousal (being awake and alert)

** Notice these are functions necessary for survival.

* Cranial nerves: Most of the cranial nerves come from

the brainstem.

* as a pathway: The brainstem is the pathway for all

fiber tracts passing up and down from

peripheral nerves and spinal cord to the

highest parts of the brain.

^ brain death: The brain can survive for up to about

4-6 minutes after the heart stops.

If CPR is started within six minutes

of cardiac arrest, the brain may

survive the lack of oxygen. After

about 6 minutes without CPR,

however, the brain begins to die.

Brain death is defined as the

irreversible loss of all functions of

the brain.

It can be determined in several ways.

1.) No electrical activity in the brain; this is

determined by an EEG.

2.) No blood flow to the brain; this is

determined by blood flow studies.

3.) Absence of function of all parts of the

brain - as determined by clinical

assessment.

- no movement

- no response to stimulation

- no breathing

- no brain reflexes.

4.) The patient can be given 1 mg of atropine

IV. In the patient with an intact brain,

atropine will dramatically increase the

patient's heart rate. In a brain-dead

patient, atropine will not influence heart

rate.

* Reticular activating system: serves to alert the rest of

the brain to incoming signals and is involved

in the sleep/wake cycle.

- Forebrain: the largest part of the brain that covers the brain’s

central core, consisting of left and right

hemispheres, which are connected by a wide band of

fibers, the corpus callosum.

Thalamus (3 actions):

1.) It integrates sensory input.

2.) It is a relay station for all the information that travels to and

from the cortex.

3.) All sensory information with the exception of smell enters

here.

Hypothalamus (4 things it controls): It regulates the ANS.

1.) Controls functions such as hunger, thirst, and sexual behavior.

2.) Controls the body’s reactions to changes in temperature.

3.) Monitors the amount of hormones in the blood.

4.) Sends out messages to correct imbalances.

"new brain": refers to the cerebral cortex.

"old brain": Subcortex and the brain stem. We share this with

animals.

Examples to describe new and old brain: Peach and peach pit

Mushroom

Cerebrospinal fluid: The entire surface of central nervous system

is bathed by a clear, colorless fluid called

cerebrospinal fluid (CSF). The CSF is

contained within a system of fluid-filled

cavities called ventricles.

- 4 functions</