Anatomy & Physiology

Anatomy & Physiology Study Guide is a modified sympathetic ganglion where preganglionic fibers synapse on neuroendocrine cells , specialized neurons that secrete hormones (chemical messengers) into the bloodstream. The neuroendocrine cells of the suprarenal medullae secrete the neurotransmitters epinephrine (E) and norepinephrine (NE). Epinephrine is commonly known as adrenaline. Parasympathetic The parasympathetic division (craniosacral) stimulates visceral activity; for example, it is responsible for the state of “rest and digest” that follows a big dinner. General parasympathetic activation conserves energy and promotes sedentary activities, such as digestion. The overall pattern of parasympathetic responses is as follows: decreased heart rate and metabolic rate, decreased blood pressure, increased secretion by salivary and digestive glands, increased motility and blood flow in the digestive tract, and stimulation of urination and defecation. The ANS also includes a third division, the enteric nervous system (ENS), which is an extensive network of neurons and nerve networks located in the walls of the digestive tract. The sympathetic division has widespread impact, reaching organs and tissues throughout the body. The parasympathetic division innervates only visceral structures. 15.4 Higher Order Functions Higher-order functions include memory and states of consciousness. Higher-order functions share three characteristics: the cerebral cortex is required for their performance, they involve both conscious and unconscious information processing, and they are not part of the programmed “wiring” of the brain. Memory Skill memories become incorporated at the unconscious level over time with repetition. Examples include the complex motor patterns involved in skiing, playing the violin, and similar activities. Skill memories related to programmed behaviors, such as eating, are stored in appropriate portions of the brain stem. Complex skill memories involve the integration of motor patterns in the basal nuclei, cerebral cortex, and cerebellum. Two classes of memories are recognized. Short-term memories, or primary memories, are those that do not last long, but the information can be recalled immediately. Primary memories contain small bits of information that are part of primary memories, such as a person’s name or a telephone number. By repeating these bits of information, it reinforces the original memory and aids its conversion to long-term memory. Memory consolidation is the conversion of a memory from short term to long term. Long-term memories last much longer, in some cases for an entire lifetime. There are two types of long-term memory: secondary memories are long-term but fade with time and may require considerable effort to recall, and tertiary memories are long-term memories that remain for a lifetime, such as one’s name or the contours of one’s own body. The s uprarenal medulla

©2018

Achieve Page 176

of 368