Peripheral Nervous System (PNS) Quiz

The Nervous System

• The peripheral nervous system (PNS) consists of smaller branches of nerves that branch out from the spinal cord and reach other parts of the body.
• The PNS conducts information from bodily organs to the central nervous system and takes information back to the organs.

Somatic Nervous System (SNS) vs. Autonomic Nervous System (ANS)

• The SNS controls voluntary activities, such as lifting your hand to turn a page.
• The ANS controls involuntary activities, such as changes in heartbeat, blood pressure, or pupil size.
• The sympathetic nervous system prepares the body for emergencies or strenuous activity, speeding up the heart and constricting/relaxing arteries.
• The parasympathetic nervous system conserves energy and enhances the body's ability to recover from strenuous activity, reducing heart rate and blood pressure.

Protection of the Nervous System

• The brain is protected by the skull and several layers of sheathing.
• The spinal cord is protected by the vertebrae.
• The peripheral nerves are protected by layers of sheathing.
• The bony protection of the spinal cord is vital, and an injury to the spinal cord could prevent message transmission between the brain and muscles, leading to paralysis.

Neurons

• Neurons are the elementary components of the nervous system.
• The human body contains billions of neurons.
• Messages to and from the brain travel along nerves, which are strings of long, thin cells called neurons.
• The neuron can fire (burn) over and over again, hundreds of times a minute.
• Transmission between neurons occurs when the cells are stimulated past a minimum point and emit a signal.
• The neuron fires according to the all-or-none principle, which states that when a neuron fires, it does so at full strength.

Basic Parts of a Neuron

• Cell body: contains the nucleus and produces energy needed to fuel neuron activity.
• Dendrites: short, thin fibers that receive impulses from other neurons and send them to the cell body.
• Axon: a long fiber that carries impulses away from the cell body toward the dendrites of the next neuron.
• Axon terminals: small fibers that branch out at the end of the axon.
• Myelin sheath: a white fatty substance that protects and insulates the axon, speeding transmission of impulses.

Cerebral Hemisphere

• The cerebral hemisphere is connected by a band of fibers called the corpus callosum.
• Each cerebral hemisphere has deep grooves, marking regions or lobes.
• The occipital lobe processes visual signals, and damage to this area can cause visual problems.
• The parietal lobe is concerned with information from the senses from all over the body.
• The temporal lobe is concerned with hearing, memory, emotion, and speaking.
• The frontal lobe is concerned with organization, planning, and creative thinking.

Split-Brain Operations

• In a normal brain, the two hemispheres communicate through the corpus callosum.
• Separating the brain hemispheres can lessen the number and severity of seizures but also implies that the brain cannot communicate with each other.
• Research on split-brain patients has presented evidence that each hemisphere of the brain is unique with specialized functions and skills.

The Role of the Brain in Behavior

• The brain influences behavior through the release of chemicals as neurotransmitters or hormones.
• Norepinephrine is a hormone when secreted into the blood by the adrenal glands but a neurotransmitter when released by the sympathetic motor neurons of the peripheral nervous system.

Heredity, Environment, and Behavior

• Heredity is the genetic transmission of characteristics from parents to offspring.
• The nature-nurture debate refers to the role of biological makeup (nature) versus environmental factors (nurture) in shaping behavior.
• Genes are the basic units of heredity, reproduced and passed along from parent to child.
• Twin studies show that genes are important for certain traits, but the environment can also influence behavior.

Implications for Practice

• Understanding the biological basis of behavior can inform healthcare practices, such as identifying those at greatest risk for psychopathology and developing new therapeutic approaches.