THE BRAIN: the Neuron/brain cell

 

EVERYTHING PSYCHOLOGICAL IS ALSO BIOLOGICAL.EVERYTHING PSYCHOLOGICAL IS ALSO BIOLOGICAL.

 To understand things like sleep and dreams, depression and schizophrenia, hunger and sex, stress and disease, we must understand human BIOLOGY.

 

I. The foundation: Neuron/nerve cells.

A.. 100 100 billion +, throughout the body

B. they ZAP - they communicate, and send ELECTRICAL messages.

C. they ZAP - send CHEMICAL messages

D. Every mood/urge/thought you have is zapped, and it is chemical

 

Neural and Hormonal Systems

Will Explain Why We FEEL……

Pain

Strong

Sick

Nervous

It all Starts with the Neuron

Neuron Structure

Neurons do NOT touch each other- the space in between is called synaptic cleft.

Neural Bases of Psychology: The Structure of a Neuron

Dendrite Fine hair-like extensions on the end of a neuron. Function: receive incoming stimuli.

Cell Body or Soma The control center of the neuron. Function: Directs impulses from the dendrites to the

axon. Nucleus Control center of the Soma.

Function: Tells the soma what to do. Axon Pathway for the nerve impulse (electrical message)

from the soma to the opposite end of the neuron. Myelin Sheath An insulating layer around an axon. Made

up of Schwann cells. Nodes of Ranvier Gaps between schwann cells.

Function: to keep charge going through the relatively long axon – without these spaces, the charge might lose its intensity before reaching the end of the cell

How Do Neurons Operate? Neuron at Rest Resting Potential

Occurs when the neuron is at rest. A condition where the outside of the membrane is positively(+)

charged compared to the inside which is negatively(-) charged. Neuron is said to be polarized.

Neural Bases of Psychology: Neural Communication

• Within a neuron, communication occurs through an action potential (neural impulse that carries information along the axon of a neuron).

Steps of Action Potential• Dendrites receive neurotransmitter from

another neuron across the synapse.• Reached its threshold- then fires based on the

all-or-none response.• Opens up a portal in axon, and lets in positive

ions (Sodium) which mix with negative ions (Potassium) that is already inside the axon (thus Neurons at rest have a slightly negative charge).

• The mixing of + and – ions causes an electrical charge that opens up the next portal (letting in more K) while closing the original portal.

• Process continues down axon to the axon terminal.

• Terminal buttons turns electrical charge into chemical (neurotransmitter) and shoots message to next neuron across the synapse.

Action Potential

The All-or None Response

• The idea that either the neuron fires or it does not- no part way firing.

• Like a gun

How Neurons Communicate

Which sentence most closely describes neural transmissions?

•A. an electric charge is created in the neuron, the charge travels down the cell, and chemicals are released that cross the synapse to the next cell•B. a chemical change occurs within the cell, the change causes an electric charge to be produced and the charge jumps the gap between the nerve cells.•C. the electric charge produced chemically inside a group of neurons causes chemical changes in surrounding cells

Neurotransmitters

•Chemical messengers released by terminal buttons through the synapse.

•We should know at least 6 types and what they do.

Acetylcholine•Its function is motor movement and

maybe memory.

Too much and you will….

Not enough and you will….

Lack of ACH has been linked to Alzheimer’s disease.

Dopamine• Its function is motor movement

and alertness.

Lack of dopamine is associated with Parkinson’s disease.

Overabundance is associated with schizophrenia.

Serotonin•Function deals with mood control.

Lack of serotonin has been linked to depression.

Endorphins•Function deals with pain

control.

We become addicted to endorphin causing feelings.

What are agonists and antagonists?

• They are drugs

• Agonists mimic neurotransmitters.

• Example: Nicotine is an ACh agonist

• Antagonists block neurotransmitters:

• Example: curare – a poison - is an antagonist for ACh (paralyzes you)

Agonists and Antagonists

Examples: A person smokes a cigarette. Nicotine in the blood causes an EXCITATORY action potential for acetylcholine to fire. The synaptic vesicles release the neurotransmitter acetylcholine into the synapse, and the person feels more alert

(their lungs are another matter altogether).

Examples: A person is given morphine, an opiate, at the hospital for pain from an operation. The morphine is administered into the vein, which means it goes directly into the blood. The morphine tips the +- balance, and this causes an inhibitory action potential to fire which causes the release of the neurotransmitters called endorphins. When the endorphins float across the synapse, the person doesn’t feel the pain from the surgery.

Examples: A person takes an allergy pill for seasonal allergies. The allergy pill goes into the bloodstream, and tips the +- balance. This causes an inhibitory action potential to fire for the neurotransmitter GABA. When GABA floats across the synapse, the person’s allergy symptoms are controlled. However, they are also sleepy and want to go to sleep in a hammock on a calm beach somewhere, because GABA is inhibitory and slows/calms everything down.

• You eat some bad Chinese food and feel you are losing control of your muscles. The bacteria you ingested from the food most likely interferes with the use of:

• A. serotonin

• B. insulin

• C. acetylcholine

• D. thorazine

• E. adrenaline

What is reuptake?

• The mopping up of excess neurotransmitter.

How does Prozac work?

• It is a serotonin reuptake inhibitor.

How does Cocaine work?

The white cocaine blocks the reuptake of dopamine.

Types of Neurons There are 3 types of neurons.1. Sensory Neurons Neurons located near

receptor organs (skin, eyes, ears).

Function: receive incoming stimuli from the environment.

2. Motor Neurons Neurons located near effectors (muscles and glands)

Function: Carry impulses to effectors to initiate a response.

3. Interneurons Neurons that relay messages between other neurons such as sensory and motor neurons. (found most often in Brain and Spinal chord).

Types of Neurons

Sensory Neurons(Afferent Neurons)

•Take information from the senses to the brain.

Motor Neurons(Efferent Neurons)

•Take information from brain to the rest of the body.

Central Nervous System•Made up of Brain and Spinal Chord•Made up of billions of neurons, sending electrical and chemical messages.

CNS

brainSpinal chord

Entire Nervous System

………is a communication system, much like Curtis High

School.

-

Administration/Support People Classes/Teachers/Students

•This is just like the Nervous System – it’s one big organization, divided into 1) the Central Nervous System, and 2) the Peripheral Nervous System

Administration/Support People Classes/Teachers/Students

The Nervous System

Central Nervous System

Peripheral Nervous System

These two systems are further divided into more sections:

Administration/Support People

Classes/Teachers/

Students

The Nervous System

Central Nervous System Peripheral Nervous System

BRAIN

Spinal Chord

Somatic Division/

Voluntary

Autonomic Division/

Involuntary

administrationSupport

personnel Electives Required classes

Peripheral Nervous System

CENTRAL NERVOUS SYSTEM

PERIPHERAL NERVOUS

SYSTEM

• The sensory and motor neurons that connect the central nervous system to the rest of the body.

Divisions of the Peripheral Nervous

System

Somatic and Somatic and AutonomicAutonomic

Somatic/Skeletal/ Autonomic/Voluntary Involuntary

Parasympathetic

Sympathetic

SENSORY NERVES/SENSORY NERVES/

AFFERENTAFFERENT

MOTORNERVES/MOTORNERVES/

EFFERENTEFFERENT

Divisions of the Peripheral Nervous System - illustrated

Somatic and Somatic and AutonomicAutonomic

Somatic/Skeletal/ Autonomic/Voluntary Involuntary

Parasympathetic

Sympathetic

SENSORYNERVES/SENSORYNERVES/

AFFERENTAFFERENT

MOTORNERVES/MOTORNERVES/

EFFERENTEFFERENT

• Mobilizes the body during extreme conditions• Considered “fight or flight” system• Involves E activities: emergency, excitement,

exercise, and embarassment • If you are threatened:

–Heart rate and breathing increase–Pupils dilate–Skin cold and sweaty–Bronchioles dilate–Liver releases glucose

• The PSNS performs maintenance activities and conserves body energy

• If the sympathetic stimulates, the parasympathetic slows the system back down (think of PARAchute)

• Provides homeostasis homeo = same Homeostasis means same state you were in before you saw the dog and the snake!

Think how the rightside is different fromthe left side.

A Simple Reflex

The Endocrine SystemA system of glands that secrete hormones.Similar to nervous system, except hormones work a lot slower than neurotransmitters.

Neurotransmitters

Hormones

Endocrine system

• The Pituitary gland – regulates growth, also releases a hormone called ACTH under PROLONGED stress, linked to repressed immune systems.

Endocrine systemAdrenal glands (adrenal cortex and the adrenal medulla) – the adrenal medulla, the inner part of the adrenal gland, releases stress hormones, epinephrine/adrenalineepinephrine/adrenaline – in response to short-term stress.

Endocrine system • Thyroid glands release hormones that control metabolic rate/related to food intake (these mice could also have problems in the hypothalamus)

Endocrine system

• Pancreas – releases insulin – regulates blood sugar/glucose levels. •Can become diabetic/problems with insulin.

Endocrine system • GonadsGonads – ovaries in women, testes in men. Hormones produced include estrogen/progesterone (more in female), testosterone/androgens (more in male).

Endocrine system - 3Pineal glandPineal gland – regulates sleep/wake cycles

The The amygdalaamygdala determines what is emotionally important, and a poisonous determines what is emotionally important, and a poisonous snake hissing in your path is going to be given top priority.snake hissing in your path is going to be given top priority.

To make sure we pay attention, the To make sure we pay attention, the amygdalaamygdala also helps us lay down an also helps us lay down an emotional memory of the snake. The neighboring emotional memory of the snake. The neighboring hippocampushippocampus, responsible for , responsible for processing memories for long-term storage, is activated and told by the processing memories for long-term storage, is activated and told by the amygdala to never forget the snake! Learned fear responses enhance our amygdala to never forget the snake! Learned fear responses enhance our survival chances when the threat is real. However, this process has also been survival chances when the threat is real. However, this process has also been implicated in a number of anxiety disorders.implicated in a number of anxiety disorders.

The fight-or-flight response

Stimuli comes from two areas to start things off – either the peripheral nerves (sensory neurons) or the brain – to activate the stress response system of the body.

From sensory From sensory nerves to nerves to hypothalamushypothalamus

From brain to From brain to hypothalamushypothalamus

ONE: Environmental stimuli that cause pain, an allergic reaction, or an internal stimulus caused by a fall in blood pressure. The midbrain and the thalamus relay sensory info to the hypothalamus, and to the cerebral cortex, for processing.

TWO: Fear or anxiety, real or imagined, may occur that causes the brain to go into action. In this case, messages to the hypothalamus are relayed from the upper brain structures – the cerebral cortex, the amygdala, etc.

STRESS – HOW SYSTEM WORKS

When our nervous system decides there is a threat, the system goes into action. The “fight or flight” response has been activated.

PITUITARY

The The hypothalamushypothalamus signals the signals the pituitarypituitary to to contact the contact the endocrine system, and tell the endocrine system, and tell the ADRENAL GLANDS to do their thing.ADRENAL GLANDS to do their thing.

Pituitary Pituitary glandgland

hypothalamushypothalamus

the the ADRENAL ADRENAL GLANDSGLANDS, located on , located on top of the stomach, top of the stomach, flood stress hormones flood stress hormones into the blood.into the blood.

Stress Hormones:Stress Hormones:

Epinephrine/Epinephrine/Adrenaline -Adrenaline - (know (know both names) Acts on both names) Acts on cardiovascular systemcardiovascular system

Norepinephrine –Norepinephrine – strengthens muscles strengthens muscles and sensesand senses

And………And………

the the ADRENAL ADRENAL GLANDSGLANDS, flood stress , flood stress hormones into the hormones into the blood.blood.

CORTISOLCORTISOL

Esp. under long-term Esp. under long-term stress. stress. CORTISOLCORTISOL helps our brain helps our brain process process glucoseglucose more more efficiently.efficiently.

Also SUPPRESSES Also SUPPRESSES action of immune action of immune system.system.

Glucose – brain’s fuel.Glucose – brain’s fuel.

General Adaptation SyndromeGeneral Adaptation Syndrome

A theory about how the body and brain A theory about how the body and brain PHYSICALLY process stress – 3 steps:PHYSICALLY process stress – 3 steps:

1)1) ALARMALARM

2)2) RESISTANCERESISTANCE

3)3) EXHAUSTIONEXHAUSTION

So………….. First, we do So………….. First, we do

fight-or-flight. fight-or-flight.

Then, we release cortisol. Then, we release cortisol.

Then, over time everythingThen, over time everything

breaks down – mental and physical.breaks down – mental and physical.

Don’t forget to write your answers on a separate piece of paper to grade when

you’re done!1. A neuron without terminal buttons would

be unable to

a) receive information from neighboring neurons

b) generate an action potential

c) direct the synthesis of neurotransmitters

d) secrete neurotransmitters

2. Paul Broca found that the loss of the ability to speak intelligibly is associated with damage to a region of the brain in the

a) left frontal lobe

b) thalamus

c) left temporal lobe

d) right parietal lobe

3. Scientists are able to see changes in the brain as it processes information by means of

a) lesioning

b) autopsy

c) CT

d) PET

4. The simplest behaviors we carry on

a) are learned when we are infants

b) do not involve the central nervous system

c) are called instincts

d) include sneezing and blinking

5. Of the following, the effect of the adrenalin on the body is most similar to the effect of the

a) cerebellum

b) parathyroids

c) somatic nervous system

d) sympathetic nervous system

6. Mr. Jenkins’ suffered a “stroke” as a result of a brain injury. Although he can still move the fingers on his right hand, he has lost sensation in these parts. Of the following, the site of damage to his brain is most likely in the

a) right frontal lobeb) right temporal lobec) left frontal lobed) left parietal lobe

7. Of the following, which are located exclusively in the central nervous system?

a) afferent neurons

b) interneurons

c) efferent neurons

d) glial cells

8. Which of the following glands interact(s) most directly with all of the others to help regulate body processes?

a) pituitary

b) adrenals

c) parathyroids

d) ovaries

9. Gunshot wounds, tumors, and strokes all result in

a) infections

b) significant loss of function

c) lesions

d) pain

10. Which of the following must be males?

a) dizygotic twins

b) monozygotic twins

c) down syndrome children

d) Klinefelter’s syndrome children

11. When you are walking, the brain sends messages to the skeletal muscles in the legs by way of

a) efferent fibers

b) sensory fibers

c) afferent fibers

d) central fibers

12. The hindbrain structure involved with sleep and arousal is the

a) hypothalamus

b) cerebrum

c) thalamus

d) pons

13. The basic parts of a neuron are

a) vesicles, terminal buttons, synapses

b) cell body, axon, dendrites

c) myelin, nodes, axon terminals

d) hindbrain, midbrain, forebrain

14. Branches are to trees as _______ are to neurons

a) axons

b) cell bodies

c) dendrites

d) nuclei

15. Determining the location of specific genes on specific chromosomes is referred to as

a) genetic mapping

b) phenomapping

c) chromosomal atlasing

d) genome projection

Chapter 3 Answer Key

1. D

2. A

3. D

4. D

5. D

6. D

7. B

8. A

9. C

10. D

11. A

12. D

13. B

14. C

15. A