The Nervous System and the Brain

The Nervous System

• The human nervous system is involved in thinking, dreaming, feeling, moving, and much more. It is working when we are active or still, awake or asleep. The nervous system regulates our internal functions. It is also involved in how we react to the external world. Even learning and memory are made possible by the nervous system. When we learn a new behavior or acquire new information, the nervous system registers that experience and changes to accommodate its storage.

• Central Nervous System– Brain and spinal cord– Spinal reflexes

• Peripheral Nervous System– Responsible for

transmitting messages between the CNS and all other parts of the body

– Somatic nervous system– Autonomic nervous system

• Sympathetic

• Parasympathetic

Human Nervous System

Central Nervous System (CNS)Brain and spinal cord

Peripheral Nervous System (PNS)Everything else

Sensory and motor neurons

Somatic Nervous SystemVoluntary

Input from sense organsOutput to skeletal muscles

Autonomic Nervous SystemInvoluntary

Input from internal receptorsOutput to smooth muscle and glands

Sympathetic Motor SystemFight or flight response

Neurotransmitter noradrenalinAdrenergic System

Parasympathetic Motor SystemRelaxing responses

Neurotransmitter acetylcholineCholinergic system

Neurons

• Components– Cell body– Dendrites– Axon

• The Communication Process– Messages are sent from one neuron to another

across the synapse (gap between axon terminals of one neuron and the dendrites of another neuron)

– Messages are sent via neurotransmitters

Quick Quiz 1

1. How do messges travel from one neuron to another?

2. Identify the systems that make up the peripheral nervous system.

3. CRITICAL THINKING: In what way do the parasympathetic and sympathetic nervous systems work together?

The Brain: Our Control Center

• Every person is unique in part because of the capacities of learning and thought made possible by the human brain. In ancient times they did not believe that brain was as complex as we now know it is. Today, however, we recognize that the mind, or consciousness, dwells within the brain. We now have greater understanding of the brain and the links between biological processes and psychological phenomena.

Parts of the Brain

• Hindbrain– Medulla– Pons– Cerebellum

• Midbrain– Vision and hearing– Reticular activating system

• Forebrain– Thalamus– Hypothalamus– Limbic system– Cerebrum

• Cerebral cortex

The Cerebral Cortex: What Makes Us Unique

• Senses and Motor Behavior

• Association Areas

• Language Abilities

Left Brain versus Right Brain

• Hemispheres do not act entirely independent although they are capable of working alone

• Left Brain– Logical– Controls the right side of

the body

• Right Brain– Creative – Controls the left side of the

body

Methods of Studying the Brain

• Accidents • Electrical Stimulation

of the Brain• The

Electroencephalogram• Scans

Quick Quiz 2

1. Why is the Cerebral cortex important2. Describe two differences between the left

hemisphere and the right hemisphere of the cerebral cortex

3. List three different imaging techniques used to study the brain.

4. CRITICAL THINKING: Why do you think it benefits people to have brains that are flexible? What would happen if brains were not flexible?

The Endocrine System

• The Pituitary Gland• The Thyroid Gland• The Adrenal Glands• The Testes and the

ovaries– Testosterone– Estrogen and

Progesterone

Quick Quiz 3

1. List and describe the role of the hormones produced by the pituitary gland, the thyroid gland, the adrenal glands, and the testes and the ovaries.

2. CRITICAL THINKING: What might psychologists learn about behavior by studying the sex hormones?

Heredity: Our Genetic Background

• Genes and Chromosomes– Shape everything from

physical characteristics to behavior

– 46 chromosomes organized into 23 pairs

• The Nature Nurture Debate– Genes or environment

Kinship Studies

• Twin studies• Adoptee studies• Twins reared apart

studies

Quick Quiz 4

1. Define gene and chromosome.

2. Describe two methods used to study the role of heredity in determining traits.

3. CRITICAL THINKING: Some traits such as extreme shyness have been shown to be partially determined by heredity. What aspects of the environment might also affect whether a person is shy?