Which system calms the body

Autonomic nervous system picture. Share on Pinterest Illustration by Diego Sabogal. Parasympathetic nervous system and your heart. Parasympathetic cranial nerves. Sympathetic and parasympathetic nervous system.

Key areas affected include the lungs, heart, smooth muscle, and exocrine and endocrine glands, like the sweat glands and saliva. Actions Constricts pupils; causes salivation; slows down the heart rate; tightens the bronchi in the lungs; enacts digestion; releases bile; makes the bladder contract Dilates pupils; keeps you from salivating; speeds up the heart; widens the bronchi; inhibits digestion; keeps the bladder from contracting Speed Slower than the sympathetic division Faster than the PSNS.

Examples of parasympathetic responses. The takeaway. Read this next. Autonomic Dysfunction. Medically reviewed by Judith Marcin, M. Medically reviewed by Deborah Weatherspoon, Ph. Medically reviewed by Timothy J. Changes in sympathetic nervous activity are evident in the skin, pupils and especially the heart. Parkinson's damages the sympathetic neurons that help maintain levels of epinephrine and norepinephrine in the body — chemicals that tell the heart when to pump harder, such as when you move to stand up or exercise.

Damage to these neurons can result in a lack of blood flow in patients with Parkinson's, so they often feel lightheaded upon standing, which dramatically increases their risk of falls.

Sympathetic dysfunction also underlies mental health conditions such as anxiety, depression and chronic stress, an article in Forbes reported. In short bursts, the body's physical stress response can be useful and grant an energizing boost of mental focus. If prolonged, however, the stress signals whizzing through the body wreak havoc. Besides maintaining a mental feeling of constant stress, the extra epinephrine and cortisol damage blood vessels, increase blood pressure and promote a buildup of fat.

So, while the fight-or-flight response serves a purpose, you don't want it switched on all the time. Nicoletta Lanese is a staff writer for Live Science covering health and medicine, along with an assortment of biology, animal, environment and climate stories.

She holds degrees in neuroscience and dance from the University of Florida and a graduate certificate in science communication from the University of California, Santa Cruz. Live Science. Reflexes can be categorized as either monosynaptic or polysynaptic based on the reflex arc used to perform the function.

Monosynaptic reflex arcs, such as the knee-jerk reflex, have only a single synapse between the sensory neuron that receives the information and the motor neuron that responds.

Polysynaptic reflex arcs, by contrast, have at least one interneuron between the sensory neuron and the motor neuron. An example of a polysynaptic reflex arc is seen when a person steps on a tack—in response, their body must pull that foot up while simultaneously transferring balance to the other leg. Privacy Policy.

Skip to main content. Biological Foundations of Psychology. Search for:. The Nervous System. Introduction to the Nervous System The nervous system controls bodily function by gathering sensory input, integrating that information internally, and communicating proper motor output. Learning Objectives Describe the hierarchical structure of the nervous system. The most basic unit of the nervous system is the neuron, which serves as both a sensor and communicator of internal and external stimuli.

The nervous system can be broken down into two major parts—the central nervous system and the peripheral nervous system. The central nervous system, the main data center of the body, includes the brain and spinal cord. The peripheral nervous system includes all of the neurons that sense and communicate data to the central nervous system.

The peripheral nervous system can be further divided into the autonomic system, which regulates involuntary actions, and the somatic system, which controls voluntary actions.

Key Terms central nervous system : In vertebrates, the part of the nervous system comprising the brain, brainstem, and spinal cord. Neurons are connected by synapses. The Central Nervous System CNS The central nervous system is made up of the brain and spinal cord, which process sensory input and provide instructions to the body.

Learning Objectives Describe the structural elements of the central nervous system. The CNS is the main control center of the body—it takes in sensory information, organizes and synthesizes this input, then provides instructions for motor output to the rest of the body. The CNS is made up of the brain and spinal cord. The brain is the main data center of the body, consisting of the cerebrum which regulates higher-level functioning such as thought and the cerebellum which maintains coordination.

The brain stem includes the midbrain, pons, and medulla, and controls lower-level functioning such as respiration and digestion. Research suggests that chronic stress contributes to high blood pressure, promotes the formation of artery-clogging deposits, and causes brain changes that may contribute to anxiety, depression, and addiction.. More preliminary research suggests that chronic stress may also contribute to obesity, both through direct mechanisms causing people to eat more or indirectly decreasing sleep and exercise.

The stress response begins in the brain see illustration. When someone confronts an oncoming car or other danger, the eyes or ears or both send the information to the amygdala, an area of the brain that contributes to emotional processing.

The amygdala interprets the images and sounds. When it perceives danger, it instantly sends a distress signal to the hypothalamus. When someone experiences a stressful event, the amygdala, an area of the brain that contributes to emotional processing, sends a distress signal to the hypothalamus. This area of the brain functions like a command center, communicating with the rest of the body through the nervous system so that the person has the energy to fight or flee.

The hypothalamus is a bit like a command center. This area of the brain communicates with the rest of the body through the autonomic nervous system, which controls such involuntary body functions as breathing, blood pressure, heartbeat, and the dilation or constriction of key blood vessels and small airways in the lungs called bronchioles.

The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system functions like a gas pedal in a car. It triggers the fight-or-flight response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system acts like a brake.

It promotes the "rest and digest" response that calms the body down after the danger has passed. After the amygdala sends a distress signal, the hypothalamus activates the sympathetic nervous system by sending signals through the autonomic nerves to the adrenal glands.

These glands respond by pumping the hormone epinephrine also known as adrenaline into the bloodstream. As epinephrine circulates through the body, it brings on a number of physiological changes. The heart beats faster than normal, pushing blood to the muscles, heart, and other vital organs. Pulse rate and blood pressure go up. The person undergoing these changes also starts to breathe more rapidly.

Small airways in the lungs open wide. This way, the lungs can take in as much oxygen as possible with each breath. Extra oxygen is sent to the brain, increasing alertness. Sight, hearing, and other senses become sharper.