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Nervous system anatomy and physiology
Neuron action potential
Blood brain barrier
Ascending and descending spinal tracts
Pyramidal and extrapyramidal tracts
Muscle spindles and golgi tendon organs
Spinal cord reflexes
Sensory receptor function
Sympathetic nervous system
Parasympathetic nervous system
Enteric nervous system
Body temperature regulation (thermoregulation)
Hunger and satiety
Basal ganglia: Direct and indirect pathway of movement
Parasympathetic nervous system
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male erection p. 651
Sam Gillespie, BSc
The nervous system is divided into the central nervous system, so the brain and spinal cord, and the peripheral nervous system, which includes all the nerves that connect the central nervous system to the muscles and organs.
The peripheral nervous system can be divided into the somatic nervous system, which controls voluntary movement of our skeletal muscles, and the autonomic nervous system, which is further divided into the sympathetic and the parasympathetic, and controls the involuntary movement of the smooth muscles and glands of our organs.
The sympathetic and parasympathetic nervous systems have opposite effects on the body.
The sympathetic nervous system controls functions like increasing the heart rate and blood pressure, as well as slowing digestion. All of this maximizes blood flow to the muscles and brain, and can help you either run away from a threat or fight it, which is why it’s also called the fight-or-flight response.
The parasympathetic nervous system instead slows the heart rate and stimulates digestion - the effects can be summarized as 'rest and digest'.
Now, neurons are the main cells of the nervous system. They’re composed of a cell body, which contains all the cell’s organelles, and nerve fibers, which are projections that extend out from the neuron cell body. These are either dendrites that receive signals from other neurons, or axons that send signals along to other neurons.
The parasympathetic nervous system is one of two divisions of the autonomic nervous system (ANS), the other being the sympathetic nervous system. The ANS controls the body's automatic or unconscious functions, such as heart rate, digestion, and breathing.
The activity of the parasympathetic nervous system can be summarized as �rest and digest' because it slows the heart rate and keeps the body's energy use as low as possible to stimulate organs like the gastrointestinal tract and the bladder.
In the parasympathetic nervous system, preganglionic cholinergic neurons release acetylcholine to activate postganglionic cholinergic neurons, which then release acetylcholine to target cells. Thus, their nerve fibers are referred to as cholinergic fibers.
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