The autonomic system is the part of the peripheral nervous system that is responsible for regulating involuntary body functions, such as heartbeat, blood flow, breathing, and digestion.
What is the function of the autonomic nervous system? a control system that acts largely unconsciously and regulates bodily functions such as the heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal.
25 Cards in this Set
| What is the sensory function of the ANS? | Perceives visceral sensations or emotions. |
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| when does the sympathetic division of ANS respond and stimulate its effectors | Dominates when the body undergoes physical or emotional stress such as hemorrhagin, embaressment, exercise, or excitement. |
The sympathetic system controls “fight-or-flight†responses. In other words, this system prepares the body for strenuous physical activity. The events that we would expect to occur within the body to allow this to happen do, in fact, occur. The parasympathetic system regulates “rest and digest†functions.
The ANS regulates the internal organs to maintain homeostasis or to prepare the body for action. The sympathetic branch of the ANS is responsible for stimulating the fight or flight response. The parasympathetic branch has the opposite effect and helps regulate the body at rest.
Listen to pronunciation. (AW-toh-NAH-mik NER-vus SIS-tem) The part of the nervous system that controls muscles of internal organs (such as the heart, blood vessels, lungs, stomach, and intestines) and glands (such as salivary glands and sweat glands).
The hypothalamus is the key brain site for central control of the autonomic nervous system, and the paraventricular nucleus is the key hypothalamic site for this control.
autonomic tone: tendency of an organ system to be governed by one division of the autonomic nervous system over the other, such as heart rate being lowered by parasympathetic input at rest.
The spinal cord serves as a conduit for signals between the brain and the rest of the body. It also controls simple musculoskeletal reflexes without input from the brain. The brain is responsible for integrating most sensory information and coordinating body function, both consciously and unconsciously.
THE AUTONOMIC NERVOUS SYSTEM AND THE HEARTThe sympathetic nervous system (SNS) has a wide variety of cardiovascular effects, including heart-rate acceleration, increased cardiac contractility, reduced venous capacitance, and peripheral vasoconstriction.
The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person's conscious effort. Disorders of the autonomic nervous system can affect any body part or process.
The visceral (or autonomic) motor system controls involuntary functions mediated by the activity of smooth muscle fibers, cardiac muscle fibers, and glands. Although these divisions are always active at some level, the sympathetic system mobilizes the body's resources for dealing with challenges of one sort or another.
The two divisions of the autonomic nervous system are the sympathetic division and the parasympathetic division. The sympathetic system is associated with the fight-or-flight response, and parasympathetic activity is referred to by the epithet of rest and digest. Homeostasis is the balance between the two systems.
In the autonomic nervous system, acetylcholine (ACh) is the neurotransmitter in the preganglionic sympathetic and parasympathetic neurons. These are shown in Figure 11.2 as the red ACh in the ganglion.
The autonomic nervous system (ANS) is the part of the nervous system that regulates involuntary functions. 1. Examples are the heartbeat, the digestive functions of the intestines, control of respiration, and secretion by glands.
ANS General Features: Two Neurons. Visceral efferent (VE) pathways that innervate smooth muscle, cardiac muscle, and glands involve two neurons and a synapse within an autonomic ganglion. The advantage of two neurons is conservation of space in the CNS, by shifting neurons into the spacious periphery.
Most preganglionic neurons in the sympathetic pathway originate in the spinal cord. Slowing of the heartbeat is a parasympathetic response. Parasympathetic neurons are responsible for releasing norepinephrine on the target organ, while sympathetic neurons are responsible for releasing acetylcholine.
Sympathetic System; OverviewThe primary neurotransmitter in preganglionic sympathetic neurons is acetylcholine (ACh), which activates neurons in the sympathetic ganglion neurons and adrenal medulla via ganglion-type nicotinic ACh receptors.
The postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors. The chromaffin cells of the adrenal medulla are analogous to post-ganglionic neurons—the adrenal medulla develops in tandem with the sympathetic nervous system and acts as a modified sympathetic ganglion.
Both sympathetic and parasympathetic preganglionic neurons are cholinergic, meaning they release acetylcholine (Ach) at the synapse in the ganglion. In the parasympathetic system, postganglionic neurons are also cholinergic.
Ganglia are clusters of nerve cell bodies found throughout the body. They are part of the peripheral nervous system and carry nerve signals to and from the central nervous system.
The autonomic nervous system is important for homeostasis because its two divisions compete at the target effector. The balance of homeostasis is attributable to the competing inputs from the sympathetic and parasympathetic divisions (dual innervation).
eg, the sympathetic nervous system can accelerate heart rate, widen bronchial passages, decrease motility (movement) of the large intestine, constrict blood vessels, cause pupil dilation, activate goose bumps, start sweating and raise blood pressure.
The apneustic center sends signals for inspiration for long and deep breaths. It controls the intensity of breathing and is inhibited by the stretch receptors of the pulmonary muscles at maximum depth of inspiration, or by signals from the pnuemotaxic center. It increases tidal volume.
Autonomic functions include control of respiration, cardiac regulation (the cardiac control center), vasomotor activity (the vasomotor center), and certain reflex actions such as coughing, sneezing, swallowing and vomiting.
The autonomic nervous system helps maintain homeostasis through the involuntary activity of autonomic reflexes. these reflexes enable the ANS to control visceral function: smoother muscle contractions ( or relaxation), cardiac muscle contractions, or stimulation of inhibition of secretion by glands.
Increased arterial pressure stretches the wall of the blood vessel, triggering the baroreceptors. These baroreceptors then feedback to the autonomic nervous system. The ANS then acts to reduce the heart rate via the efferent parasympathetic fibres (vagus nerve). This reduces the blood pressure.
