How the nervous system

works

1. It never rests

2. Controls our emotions,

movements, thinking and

behavior

3. It is divided into 2 parts

Central Nervous System

(CNS); consists of the

brain and spinal cord

How the nervous system works (cont.)

4. Peripheral Nervous System (PNS)

a. Smaller Branches of nerves

that reach other parts of the body

from the spinal cord (thickness of

a pencil)

b. Take information from the

organs to the CNS and from the

CNS back to the organs

5. Each is protected by something

a. Brain by the skull and several

layers of sheathing

b. Spinal cord by the vertebrae

c. Peripheral nerves by layers of

sheathing

Neurons

1. Nerves are long,

thin cells called

neurons

a. Messages

travel along

these

b. Neurons

can “fire”

(transmit

signals) 100s

of times/min.

2. Neurons have

three basic parts

a. The cell

body

(contains

the nucleus

and produces

the energy

needed to

fuel neuron

activity)

b. Dendrites

(short, thin fibers

that stick out from

the cell body;

receive impulses

from other neurons,

send them to the

cell body

c. Axons (Long

fiber that carries

the impulses

away from the

cell body toward

the dendrites of

the next neuron

d. Other structures

1. Myelin Sheath (white,

fatty substance insulates

and protects the axon)

i. If destroyed,

behavior can be

erratic, uncoordinated

(as in MS)

ii. Speeds

transmission of

impulses

2. Axon terminals–

branch out from the end

of the axon, they are

positioned directly

opposite of the dendrite

Neuron connection

1. Synapse– the space between the axon terminals of one neuron

and the dendrites of another neuron.

a. This is the junction or connection between neurons

b. Neurons transmit impulses or messages across this space

using

neurotransmitters

c. Neurotransmitters – are chemicals that either excite the next neuron

or stop it from transmitting

i. There are different types of neurotransmitters

a. Norepinephrine– involved in memory

or learning

b. Endorphin– inhibits pain

c. Acetylocholine– involved in movement

and memory (associated with paralysis

and Alzheimer’s)

d. Dopamine– involved in learning,

emotional arousal and movement (too

much associated w/schizophrenia; too little

w/Parkinson’s

e. Serotonin (an undersupply linked with

a lack of norepinephrine is associated with

depression)

Voluntary and

Involuntary Activities

1. Somatic Nervous

System (SNS)– refers

to the part of the

PNS that controls

voluntary activities

a. Body making

a response to impulses from the nerves, like

turning a page in a book once you’ve reached the

end, or tracking down a fly ball

Voluntary and Involuntary Activities (cont.)

2. Autonomic Nervous System (ANS) – refers

to the part of nervous system that controls

involuntary activities, or those that occur

automatically

a. Your heartbeat, breathing, stomach

activity

b. Has two parts

Voluntary and Involuntary

Activities (cont.)

i. Sympathetic nervous

system– prepares the

body for dealing

w/emergencies or

strenuous activities

a. Speeds up the

heart to hasten

supply of blood,

nutrients to the

body

Voluntary and Involuntary

Activities (cont.)

ii. Parasympathetic nervous

system– works to

conserve energy/

enhance the body’s

ability to recover from

strenuous activity

a. Reduces heart

rate and blood

pressure to bring

the body back to its

resting state

The Brain is composed of 3 parts: the hindbrain, midbrain,

and forebrain

1. The Hindbrain

a. Located at the

rear base of the

skull

b. Involved in the

most basic

processes of life

c. Includes:

i. cerebellum

ii. medulla

iii. pons

2. The Midbrain

a. Integrates

sensory

information

b. Alerts the rest

of the brain to

incoming signals

and is involved in

the sleep/wake

cycle

3. The Forebraina. All information from the senses (minus

smell) come through the thalamus

b. Controls: hunger, thirst, sexual behavior,

reaction to temperature

c. Higher level thinking processes

i. Ability to learn and store complex and

abstract information; project thinking into

the future

ii. See, read and understand

iii. Regulates emotions and motivations

3. The Forebrain (cont.)

d. Includes:

i. Thalamus

ii. Cerebral Cortex

iii. Cerebrum

iv. Limbic System

a. Hypothalamus,

amygdala

(violent emotions

and fear),

thalamus and

hippocampus

(memory)

Lobes of the Brain

1. Cerebrum is split into 2 sides or hemispheres

a. Connected by the corpus callosum

2. Occipital Lobe

a. Where visual

signals are processed

b. Damage may

cause visual impairment

3. Parietal Lobe

a. Receives and

deals with info from all

the senses

4. Temporal Lobe

a. Concerns: hearing,

memory, emotion and

thinking

5. Frontal Lobe

a. Concerned with

organization, planning

and creative thinking

6. Somatosensory Cortex

a. Receives information from the touch sensors

7. Motor Cortex

a. Sends information to control body movement

The Hemispheres

1. Each work together to compliment and help each

other

2. Corpus callosum carries information back and forth

between the hemispheres and the lobes (each of the 4

lobes are present in both hemispheres)

3. Left Hemisphere

a. Controls movement on the right side of the body

b. Where speech is located (in most people)

c. Specialized for mathematical ability, calculation

and logic

The Hemispheres (cont.)

4. Right Hemisphere

a. Controls the left side

of the body

b. Adept at visual and

spatial relations

c. Perceptual tasks

d. Recognizing patterns

(music and art)

e. Creativity and intuition

Split-Brain Operations

1. Usually done to those with severe seizures

2. Cuts the corpus callosum

a. Lowers the severity and number of seizures

b. Information cannot cross into other spheres

i. Person with a split brain can hold a ball in their

right hand and say it was a ball, but not holding it

in their left hand.

3. Shows how unique and the specialize functions and

skills of each hemisphere

4. Remained practically unchanged in intelligence,

emotion and personality

How do Psychologists study

the brain?

1. Recording

a. Electrodes into the brain to record electrical activity

b. EEG– electroencephalograph: millions of neurons

can be studied at one time via EEG

c. Shows brain waves which show

the amount of neural activity

2. Stimulation

a. Fires off neurons by electricity

b. Can show what areas of the

brain do/are responsible for smells,

music, etc.

How do Psychologists study the brain? (cont.)

3. Lesions

a. Cutting or destroying areas of healthy brain tissue

and studying the results

4. Accidents

a. Studying the results

of accidents and medical

issues

i. Phineas Gage

ii. Coma patients

iii. Traumatic head

injuries

5. Images

a. CAT (Computerized Axial Tomography) scans

i. Transfers the amount of radiation absorbed

by the density of brain tissue into a 3

dimensional view of the brain

b. PET (Positron Emission Tomography) scans

i. Shows the absence or presence state of

activity in an area of the brain through

radioactive dye

c. MRI (Magnetic Resonance Imaging)

i. Ability to study both activity and brain

structure

ii. Uses both CAT and PET scanning

capabilities

d. fMRI (Functional Magnetic Resonance

Imaging)

i. New, can see the blow flow into active

areas to determine activity and functionality

Endocrine system– sends chemical messages to and

from the brain

1. Hormones: chemical messengers/messages

a. Produced by glands; sent by blood, other bodily

fluids

b. Once in the bloodstream, they can only be

received by the specific organs they can influence

c. Ductless (don’t need pores/ducts) to release to an

organ (sweat glands, tear glands, salivary glands)

d. Various effects on behavior and moods

e. Growth of organs, muscles and bones

Glands of the Endocrine System

2. Pituitary Gland

a. Directed by the

hypothalamus

b. Secretes a large

number of hormones,

many of which control the

output of other hormones

i. Corrects imbalances

of hormones in the body

ii. Keeps metabolism in check despite outside

influences

iii. Control growth and reproduction

Glands of the Endocrine System (cont.)3. Thyroid Gland

a. Produces thyroxine

i. Stimulates

chemical

reactions for

all tissues

ii. Too little,

people feel

lazy; too

much,

people lose

weight,

sleep too

much, and are overactive

Glands of the Endocrine System (cont.)4. Adrenal Gland

a. Become active when someone is angry or frightened

b. Release Epinephrine (adrenaline) and norepinephrine

(noradrenaline)

c. Speed up heart rate, breathing; heighten emotion; extra energy

d. Secret cortical steroids

i. Help muscle develop and cause the liver to release stored sugar

for extra energy in emergencies

Glands of the Endocrine System (cont.)

5. Sex Glands

a. 2 Types

i. Testes– male; produce sperm and testosterone

(sex hormone)

ii. Ovaries– female; produce eggs and estrogen and

progesterone

b. Testosterone

i. Important to physical development of males during the

prenatal and adolescence periods

a. Prenatal– helps decide the sex of the fetus

b. Adolescence– development of bone and muscle,

male sex characteristics

c. Estrogen and progesterone

i. Development of the female sex characteristics

ii. Regulate the reproductive cycle

iii. Variances of the hormones cause the

symptoms of PMS

6. Hormones vs. Neurotransmitters Difference

a. When a chemical is released next to a cell to excite or

inhibit it = neurotransmitter

b. When a chemical is released into the blood = hormone

Glands of the Endocrine System (cont.)

1. Is human behavior instinctive (due to heredity) or

learned (environment)

a. Heredity is the genetic transmission of

characteristics from parents to their offspring

2. Nature vs. Nurture

a. Genes and behavior

i. Reproduced and

passed onto children

ii. Occur through their

role in building and

modifying the physical

structures of the body

b. Twin studies

i. Identical twins:

develop from the

same single,

fertilized egg,

thus sharing the

same genes

ii. Fraternal

twins: develop

from 2 fertilized

eggs, not more

similar genes

than brothers or

sisters

b. Twin studies (cont.)

iii. One study showed that twins growing up apart

from one another showed similar behaviors,

despite different socials, cultural and economic

backgrounds

a. Suggests heredity may contribute to

behaviors once thought to be more due to

environment than nature

b. It is possible though to alter the

environment that genes operate in, thus

changing these “hereditary” ideas