Differences Between Sympathetic and Parasympathetic Nervous Systems PDF

**DIFFERENCES BETWEEN SYMPATHETIC AND PARASYMPATHETIC NERVOUS SYSTEMS** 1. Autonomic visceral effector pathways of sympathetic nervous system always consist of two neurons: preganglionic and postganglionic, having their cell bodies in the lateral grey horn of the spinal cord in the thoracico-lum...

**DIFFERENCES BETWEEN SYMPATHETIC AND PARASYMPATHETIC NERVOUS SYSTEMS** 1. Autonomic visceral effector pathways of sympathetic nervous system always consist of two neurons: preganglionic and postganglionic, having their cell bodies in the lateral grey horn of the spinal cord in the thoracico-lumbar regions ie 1 to 12 thoracic segments and first 2 lumbar segments. The fibres of the preganglionic neurons are then known as the thoraco-lumbar outflow. The sympathetic trunk consists of a linear series of 22 ganglia. Because of the presence of the ganglionic chain closer to the spinal cord and away from the target organs and muscles, the preganglionic fibres are shorter and the postganglionic fibres are longer making it a faster system. - 2. Within the human body there are lots of receptors that receive messages from certain biologic messengers in [order](http://www.differencebetween.net/miscellaneous/difference-between-judgment-and-order/) for the specific body systems to function or make an appropriate response. Like the autonomic nervous system (ANS), the division responsible for automatic responses like the beating of the heart and other organ functions involving smooth muscles, this system is further regulated by two specific branches called the adrenergic and cholinergic pathways. Each pathway has its own unique set of receptors and triggers to induce a certain action. The adrenergic pathway is otherwise known as the SNS or sympathetic nervous system. The other one is the cholinergic pathway which is also regarded as the parasympathetic nervous system (PNS). The main difference between the two is their neurotransmitters. For the cholinergic line, acetylcholine (ACh) is used while the adrenergic line makes use of either norepinephrine or epinephrine (also known as adrenaline); no wonder the adrenergic line came to be named as such because adrenaline is involved. Because of the action of these neurotransmitters, they will trigger different kinds of effects onto the body. Generally, the PNS or cholinergic induces the 'digest and rest' effects while the SNS or adrenergic mimics the effect of the 'fight or flight response' as in the case when there is too [much](http://www.differencebetween.net/language/difference-between-much-and-many/) excitement. Inducing the digest and rest means that the gastrointestinal (GI) and genitourinary (GU) systems' effects are increased (excited) while imitating the fight or flight response excites all other system effects except the GI and GU. The two pathways also have different kinds of receptors that are either excitatory in nature or inhibitory. Nicotinic and muscarinic receptors are part of the cholinergic line while alpha and beta receptors are part of the adrenergic line. These receptors are located in many areas within the body like for the nicotinic receptors, they are mostly found at the skeletal muscles whereas the adrenergic receptors are vastly distributed throughout many parts of the body. 3. The sympathetic nervous system is responsible for up- and down-regulating many homeostatic mechanisms in living organisms. Fibers from the SNS innervate tissues in almost every organ system, providing at least some regulation of functions as diverse as [pupil](https://en.m.wikipedia.org/wiki/Pupil) diameter, [gut motility](https://en.m.wikipedia.org/wiki/Gut_motility), and [urinary](https://en.m.wikipedia.org/wiki/Urinary_system) system output and function. It is perhaps best known for mediating the neuronal and hormonal stress response commonly known as the "*fight-or-flight response"*. This response is also known as *sympatho-adrenal response* of the body, as the [preganglionic](https://en.m.wikipedia.org/wiki/Preganglionic) sympathetic fibers that end in the [adrenal medulla](https://en.m.wikipedia.org/wiki/Adrenal_medulla) (but also all other sympathetic fibers) secrete acetylcholine, which activates the great secretion of adrenaline (epinephrine) and to a lesser extent noradrenaline (norepinephrine) from it. Therefore, this response that acts primarily on the [cardiovascular system](https://en.m.wikipedia.org/wiki/Cardiovascular_system) is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly from the adrenal medulla. The sympathetic nervous system is responsible for priming the body for action, particularly in situations threatening survival.One example of this priming is in the moments before waking, in which sympathetic outflow spontaneously increases in preparation for action. It is, therefore, primarily responsible for preparing the organism to face an emergency by mobilizing the required bodily resources. Parasympathetic division is primarily responsible for conservation of resources and energy within the body to help the body *"rest and digest"* that occur when the body is at rest, especially after eating, including [sexual arousal](https://en.wikipedia.org/wiki/Sexual_arousal), [salivation](https://en.wikipedia.org/wiki/Salivation), [lacrimation](https://en.wikipedia.org/wiki/Tears) (tears), [urination](https://en.wikipedia.org/wiki/Urination), [digestion](https://en.wikipedia.org/wiki/Digestion) and [defecation](https://en.wikipedia.org/wiki/Defecation). Its action is described as being complementary to that of the [sympathetic nervous system](https://en.wikipedia.org/wiki/Sympathetic_nervous_system). The parasympathetic division functions with actions that do not require immediate reaction. 4. +-----------------------+-----------------------+-----------------------+ | **General Body | Counterbalance; | Body speeds up, | | Response** | restores body to | tenses up, becomes | | | state of calm. | more alert. Functions | | | | not critical to | | | | survival shut down. | +=======================+=======================+=======================+ | **Cardiovascular | Decreases [heart | Increases | | System (heart rate)** | rate](https://www.dif | contraction, heart | | | fen.com/difference/He | rate | | | art_Rate_vs_Pulse) | | +-----------------------+-----------------------+-----------------------+ | **Pulmonary System | Bronchial tubes | Bronchial tubes | | (lungs)** | constrict | dilate | +-----------------------+-----------------------+-----------------------+ | **Musculoskeletal | Muscles relax | Muscles contract | | System** | | | +-----------------------+-----------------------+-----------------------+ | **Pupils** | Constrict | Dilate | +-----------------------+-----------------------+-----------------------+ | **Gastrointestinal | Increases stomach | Decreases stomach | | System** | movement and | movement and | | | secretions | secretions | +-----------------------+-----------------------+-----------------------+ | **Salivary Glands** | Saliva production | Saliva production | | | increases | decreases | +-----------------------+-----------------------+-----------------------+ | **Adrenal Gland** | No involvement | Releases adrenaline | +-----------------------+-----------------------+-----------------------+ | **Glycogen to Glucose | No involvement | Increases; converts | | Conversion (liver)** | | glycogen to glucose | | | | for muscle energy | +-----------------------+-----------------------+-----------------------+ | **Urinary Response** | Increase in urinary | Decrease in urinary | | | output | output | +-----------------------+-----------------------+-----------------------+ | **Neurotransmitters** | neurons are | neurons are mostly | | | cholinergic: | adrenergic: | | **(post-ganglionic | acetylcholine | epinephrine / | | fibres secretion)** | | norepinephrine | | | | (acetylcholine) | +-----------------------+-----------------------+-----------------------+ -- -- E:\\DOCUMENTS NEW\\ACADEMIA\\ANS.jpg [ ]