Nervous System The electrochemical communication system of the

Nervous System • The electrochemical communication system of the body • Sends messages from the brain to the body for movement • Brings information to the brain from the senses

Neuron • The basic building block of the nervous system -- a nerve cell • Neurons perform three basic tasks – Receive information – Carry the information – Pass the information on to the next neuron

Neurons • Neurons “fire” -- send an impulse down their length -- or they don’t “fire” • Neurons come in a variety of shapes, sizes, etc.

Parts of the Neuron - Terminals

Synapse • The tiny, fluid filled gap between the axon terminal of one neuron and the dendrite of another neuron • The action potential cannot jump the gap

Neurotransmitters • A chemical messenger that travels across the synapse from one neuron to the next • Can influence whether the second neuron will generate an action potential or not

A Neural Chain

The Nervous System

Central Nervous System (CNS) • The brain and spinal cord • The brain is the location of most information processing. • The spinal cord is the main pathway to and from the brain.

Peripheral Nervous System (PNS) • The sensory and motor nerves that connect the central nervous system to the rest of the body • Peripheral means “outer region” • The system is subdivided into the somatic and autonomic nervous systems.

Somatic Nervous System • The division of the peripheral nervous system that controls the body’s skeletal muscles • Contains the motor nerves needed for the voluntary muscles

Autonomic Nervous System • The division of the peripheral nervous system that controls the glands and muscles of the internal organs • Monitors the autonomic functions • Controls breathing, blood pressure, and digestive processes • Divided into the sympathetic and parasympathetic nervous systems

Sympathetic Nervous System • The part of the autonomic nervous system that arouses the body to deal with perceived threats • Fight or flight response

Parasympathetic Nervous System • The part of the autonomic nervous system that calms the body • Brings the body back down to a relaxed state

Endocrine System • One of the body’s two communication systems • A set of glands that produce hormones-chemical messengers that circulate in the blood

Hormone • Chemical messengers produced by the endocrine glands and circulated in the blood • Similar to neurotransmitters in that they are also messengers • Slower communication system, but with longer lasting effects

Pituitary Gland • The endocrine system’s gland that controls the other endocrine glands • Called the “master gland” • Located at the base of the brain and connects to the hypothalamus

Thyroid Gland • Endocrine gland that helps regulate the energy level in the body • Located in the neck

Adrenal Gland • Endocrine glands that help to arouse the body in times of stress • Located just above the kidneys • Release epinephrine (adrenaline) and norepinephrine (noradrenaline)

Pancreatic Gland • Regulates the level of blood sugar in the blood

Sex Glands • Ovaries (females) and testes (males) are the glands that influence emotion and physical development. • Testosterone – primary males hormone • Estrogen – primary female hormone • Males and females have both estrogen and testosterone in their systems.

The Brain

Brainstem • The oldest part of the brain • Is responsible for automatic survival functions • Located where the spinal cord swells and the brain just begins

Medulla • The base of the brainstem • Controls life-supporting functions like heartbeat and breathing • Damage to this area can lead to death.

Thalamus • Sits atop the brainstem • The brain’s sensory switchboard -directs messages to the sensory receiving areas in the cortex • Thalamus is Greek for “inner chamber. ”

Limbic System • A ring of structures around the thalamus; at the border of the brainstem and cerebral cortex • Helps regulate memory, aggression, fear, hunger, and thirst • Includes the hypothalamus, hippocampus, and amygdala

Hypothalamus • Located directly under the front of the thalamus • Regulates eating, drinking, body temperature, and the fight or flight reactions to stress • Plays a role in emotions, pleasure, and sexual function

Hippocampus • Wraps around the back of the thalamus • Plays a role in processing new memories for permanent storage • Looks something like a seahorse – Hippo is Greek for “horse. ”

Amygdala • Two almond shaped structures • Controls emotional responses such as fear and anger

Cerebral Cortex • The body’s ultimate control and information processing center • Covers the brain’s lower level structures • Contains an estimated 30 billion nerve cells • Divided into four lobes

Corpus Callosum • The large band of neural fibers that connects the two brain hemispheres and carries messages between them • Is sometimes cut to prevent seizures

Frontal Lobes • The portion of the cerebral cortex lying just behind the forehead • Is involved in making plans and judgments

Parietal Lobes • Regions available for general processing, including mathematical reasoning • Designated as the association lobes • Behind the frontal lobes

Occipital Lobe • The primary visual processing area • Located in the back of the head

Temporal Lobes • Includes the auditory cortex where sound information is processed • Located roughly above the ears

Motor Cortex • Area at the rear of the frontal lobes • Controls voluntary movement • Different parts of the cortex control different parts of the body. • The motor cortex in the left hemisphere controls the right side of the body and visa versa.

Somatosensory Cortex • Located in the front of the parietal lobes • Registers and processes body senses • Soma is Greek for “body. ”

Hemispheric Differences • “Left-brained” and “right-brained” debunked • Brain is divided into two hemispheres but works as a single entity. • Both sides continually communicate via the corpus callosum, except in those with split brains.

The Brain’s Left Hemisphere • For most people, language functions are in the left hemisphere. • For a small percentage of people, language functions are in the right hemisphere.

Broca’s Area • Located in the frontal lobe and usually in the left hemisphere • Responsible for the muscle movements of speech • If damaged the person can form the ideas but cannot express them as speech

Wernicke’s Area • Located in the temporal lobe • Involved in language comprehension and expression; our ability to understand what is said to us • Usually in the left temporal lobe

The Brain’s Right Hemisphere • Houses the brain’s spatial abilities • Our spatial ability allows us to perceive or organize things in a given space, judge distance, etc. • Helps in making connections between words

Plasticity • The ability of the brain tissue to take on new functions • Greatest in childhood • Important if parts of the brain are damaged or destroyed