Biology & Behavior Chapter 2. Section 1: The Nervous System

Biology & Behavior

Chapter 2

Section 1: The Nervous System

• It’s almost like running is this great friend we both share…Anyway, that’s what I’d like to talk to you about… running as a friend, as a companion, a lover even…in other words, the relationship of running. “WHAT!?” many of you will be saying. “I thought that I was going to learn how to improve my 10k time.” GO read Runner’s World for that. You see, I don’t view running as what I DO or who I AM, but as this thing, this force, that changes me over time.– From “Running and Me: A love Story” by Joan

Nesbit, 1999

Neurons

• Nerve cells that run through our entire body and communicate with one another

• 100 billion neurons, most found in brain

The Nervous System

Central Nervous System• Brain & Spinal Cord

Peripheral Nervous System• Nerve cells that send

messages between the central nervous system and all parts of the body

Parts of a Neuron• Cell body – produces

energy that fuels the activity of the cell

• Dendrites –receive information from other neurons and pass the message through the cell body

• Axons –carries messages away from cell body

• Myelin – white fatty substance that insulates and protects the axon; also speeds up transmission of messages

• Axon terminals – small fibers at the end of the axon

The Communication Process

• Messages sent from the axon terminals of one neuron to dendrites of other neurons

• Crosses synapse (junction between the axon terminals of one neuron and the dendrites of another neuron)

• Messages travel in only one direction

Neurotransmitters: Chemical Messengers

• Neurotransmitters (the message)are chemicals that are stored in axon terminals

• Neurons can fire hundreds of times every second

• Several types of neurotransmitters, each with their own structure

The Central Nervous System

• Transmits messages between the brain and the muscles and glands throughout the body

• Also involved in spinal reflexes

The Peripheral Nervous System

• Made up of the Somatic Nervous System & the Autonomic Nervous System

The Somatic Nervous System

• AKA the skeletal nervous system

• Transmits sensory messages to the CNS

• Activated by touch, pain, changes in temperature, changes in body position

• Enables us to experience hot and cold and to feel pain and pressure

• Helps us maintain posture and balance

The Autonomic Nervous System

• Regulates body’s vital functions (heartbeat, breathing, digestion, blood pressure)

• Don’t have to think about these activities...happen automatically

• Made up of the Sympathetic & Parasympathetic nervous systems

Sympathetic Nervous System

• Prepares body for action

• To either run away or confront situation

• “Fight or Flight” response

• Suppresses digestion, increases heart & respiration rates, elevates blood pressure

Parasympathetic Nervous System

• Restores the body’s reserves of energy after an action has occurred

• Heart rate & blood pressure are normalized, breathing slowed, digestion returns to normal

Nervous System

CNS

BrainSpinal Cord

PNS

Autonomic System (involuntary muscles &

internal organs)

Parasympathetic System(Calms body after emergencies

Sympathetic SystemPrepares body for

action

Somatic System (voluntary muscles &

sense organs)

For homework:

• On a half sheet of paper… explain how a neuron works using the metaphor of a relay race. Be sure to be specific and detailed in your description.

Section 2: The Brain

The Brain

• Mind, or consciousness, dwells within the brain

• Divided into 3 sections1. Hindbrain2. Midbrain3. Forebrain

http://www.youtube.com/watch?v=VF5PyeMG8Lo&safety_mode=true&persist_safety_mode=1&safe=active

Hindbrain

• Medulla oblangata – Involved in vital functions (heart rate, blood pressure, and breathing)

• Pons –regulates body movement, attention, sleep, and alertness

• Cerebellum – “little brain” – balance and coordination

Midbrain

• Vision & hearing• Contains part of

reticular activating system– Important for

attention, sleep, and arousal

– Increases heart rate & blood pressure

Forebrain

• Four major areas1. Thalamus2. Hypothalamus3. Limbic System4. Cerebrum

Thalamus

• A relay station for sensory stimulation

Hypothalamus• Regulates body temperature,

storage of nutrients, & various aspects of motivation & emotion

• Involved in hunger, thirst, sexual behavior, caring for offspring, & aggression

• Disturbances within the hypothalamus can lead to unusual drinking & eating behaviors

Limbic System

• Involved in learning and memory, emotion, hunger, sex, and aggression

• If damaged, people can recall old memories but not create new ones

Cerebrum

• Surface of cerebrum known as the cerebral cortex (outer layer of brain)

• Part that makes us uniquely human – the part that thinks

• Also deals with memory, language, emotions, complex motor functions, perception

Cerebral Cortex

• Divided into two hemispheres• Corpus Callosum connects two hemispheres• Information received by one side of the body is

transmitted to the opposite hemisphere• Each hemisphere is divided into four lobes

1. Frontal Lobe2. Parietal Lobe3. Temporal Lobe4. Occipital Lobe

Senses and Motor Behavior

• Occipital lobe contains primary visual area– Damage creates unusual conditions: may be able

to recognize an object but unable to differentiate it from another similar object

• Temporal lobe contains hearing or auditory area– If damaged a person may not be able to recognize

common sounds

• Parietal lobe – receives messages from skin senses (warmth, touch, cold, pain)

• Frontal lobe – home to the motor cortex (neurons fire when we move certain parts of our body)

Association Areas

• Shape information into something meaningful• Frontal lobe association areas where we solve

problems, make plans and decisions

Left vs. Right HemispheresLeft Hemisphere• Language functions, logic,

problem-solving, math

Right Hemisphere• imagination, art, feelings,

spatial relations

• For nearly all right-handed people, language functions are based in left hemisphere

• Language functions also based in left hemisphere for 2/3rds of left-handed people

• Although differences exist between two hemispheres, they don’t act independently of each other

How do we study the brain?• Accidents• Electrical Stimulation of the Brain – shows that specific

areas are associated with specific types of sensations• EEG – device that records electrical activity in the brain• Scans

– MRI – lie in a magnetic field – brain gives off extra energy from radio waves and creates visual images• Good for small injuries

– CAT – X-ray beams passed through head and form 3-d images of brain

– fMRI – fast kind of MRI that shows the brain at work– PET – radioactive sugar injected into body – as it reaches the

brain – more is used in areas of greater activity – images show this activity

Section 3: The Endocrine System

The Endocrine System• Glands that secrete hormones into the bloodstream• Pituitary Gland – The “master gland”– Secretes growth hormone, hormone to stimulate labor

in pregnant women• Thyroid Gland – controls metabolism

• Pineal Gland – produces melatonin & affects sexual development

• Adrenal Gland – produce adrenaline & nonadrenaline

• Testes & Ovaries – produce testosterone, estrogen, progesterone

Section 4: Heredity

Heredity

• Transmission of characteristics from parents to offspring

• Genes – basic building blocks of heredity• 46 chromosomes divided into 23 pairs• 23rd chromosome – boys xy and girls xx– Dad determines sex of offspring

Nature-Nurture Debate

• Nature– What people inherit– Inherited characteristics

determine the kind of people we are

• Nurture– Environmental factors

• Family, education, culture, living conditions, everyday experiences

• Today, most psychologists believe both are involved

Kinship Studies

• Common way to study nature vs. nurture• Twin studies – to determine which traits are

genetically inherited• Adoption studies – do kids act more like

biological or adopted parents?• Twins reared apart – still share many traits