Receptor chemoreceptor

Doses from/with smoking. Nicotine causes release of catecholamines in the CNS, also serotonin, and antidiuretic hormone, corticotrophin and growth hormone. The effects of nicotine on viscera are probably largely reflex, from stimulation of sensory receptors (chemoreceptors) in the carotid and aortic bodies, pulmonary circulation and left ventricle. Some of the results are mutually antagonistic. 

Respiratory Centers Receptors Chemoreceptors Pulmonary Acidosis Respiratory Alkalosis... 

The nervous system can be divided into three parts the central nervous system (CNS), the peripheral nervous system (PNS), and the autonomic nervous system (ANS) (Dawson et al. 2003). The CNS consists of the brain and spinal cord. The PNS resides outside the CNS and forms a network to collect information from sensory responses. The ANS is identified by primary ganglia of the head and neck, sympathetic chain and adrenal gland (Gabella and Larry 2009). The primary function of the nervous system is to receive input from the environment and innervate muscle tissues in response. To accomplish this task, neurons, which are the basic unit of the functional nervous system (Dawson et al. 2003), form a highly specific interconnecting network from the brain to the spinal cord. There are 12 paired cranial nerve and 31 paired spinal nerve connections between the CNS and the PNS, which result in motor/ efferent, sensory/afferent, or mixed function. Furthermore, internal environments such as cardiorespiratory activities, glandular secretions, vasodilatation and genital erectile tissue responses are monitored by an array of visceral receptors, chemoreceptors, and stretch receptors via autonomic nerves from the CNS (Keller et al. 2009). 

The low detection limit, high sensitivity, and fast response times of chemoreceptor-based biosensors result primarily from the extremely high binding constants of the receptor R for the target substrate S. The receptor—substrate binding may be described... 

Emesis No distinct pathway DA receptors in chemoreceptor pathway zone Vomiting Anti-emetic (not motion sickness) D2 ... 

Many different types of sensory receptors are located throughout the body. These receptors monitor the status of the internal environment or that of the surroundings. Sensory receptors are sensitive to specific types of stimuli and measure the value of a physiological variable. For example, arterial baroreceptors measure blood pressure and chemoreceptors measure the oxygen and carbon dioxide content of the blood. The information detected by these sensors then travels by way of afferent neuronal pathways to the central nervous system (CNS). The CNS is the integrative portion of the nervous system and consists of the (1) brain and the (2) spinal cord. 

Figure 15.4 Effects of the autonomic nervous system on mean arterial pressure. The baroreceptors, chemoreceptors, and low-pressure receptors provide neural input to the vasomotor center in the brainstem. The vasomotor center integrates this input and determines the degree of discharge by the sympathetic and parasympathetic nervous systems to the cardiovascular system. Cardiac output and total peripheral resistance are adjusted so as to maintain mean arterial pressure within the normal range.

Chemoreceptors. The peripheral chemoreceptors include the carotid bodies, located at the bifurcation of the common carotid arteries, and the aortic bodies, located in the aortic arch. These receptors are stimulated by a decrease in arterial oxygen (hypoxia), an increase in arterial carbon dioxide (hypercapnia),... 

The central chemoreceptors are located near the ventral surface of the medulla in close proximity to the respiratory center. These receptors are surrounded by the extracellular fluid (ECF) of the brain and respond to changes in H+ ion concentration. The composition of the ECF surrounding the central chemoreceptors is determined by the cerebrospinal fluid (CSF), local blood flow, and local metabolism. 

Explain how each of the three types of sensory receptors within the digestive tract is stimulated chemoreceptors, osmoreceptors, and mechanoreceptors... 

The simple or unconditioned salivary reflex occurs when food is present within the oral cavity and causes stimulation of chemoreceptors and pressure receptors. These receptors then transmit impulses to the salivary center in the medulla of the brainstem. Parasympathetic efferent impulses are transmitted back to the salivary glands and secretion is enhanced. 

An important gastric secretion is the hydrochloric acid that performs a number of functions in the stomach. This stomach acid is neutralized by pancreatic bicarbonate ion in the duodenum. Excess acid in the chyme stimulates chemoreceptors in the duodenum. This receptor stimulation elicits reflex inhibition of gastric motility. Excess acid also causes the release of secretin and gastric inhibitory peptide from the duodenum. These hormones contribute to inhibition of gastric contractions so that the neutralization process may be completed before additional acid arrives in chyme from the stomach. 

Chemoreceptor A sensory receptor responding to a chemical stimulus (e.g., smell or taste) or change in the concentration of a chemical (e.g., H+ ions in the blood or PH). 

Membrane-associated receptors are linked to transducing proteins (like G-proteins) in the inner portion of the membrane. G-protein coupled receptor (GPCR) families comprise a major class of the receptors that are pharmacologically relevant, such as muscarinic acetyl choline receptors, adrenoceptors, dopamine receptors, serotonine, opiate, peptide hormone, purinerg receptors, and also sensory chemoreceptors. A large variety of subtypes are described in the pharmacological literature. 

Lobster chemoreceptor cells show a great diversity of filter properties. Electrophysiological measurements show that each receptor cell is tuned not only to one or a few preferred compounds (12, 13) but also to a preferred frequency (14, 15). Temporal resolution in chemoreception is affected by at least five different stimulus parameters rate of stimulus concentration increase (= pulse slope), amplitude and duration of a... 

Metoclopramide is a dopamine receptor antagonist, which acts selectively on the chemoreceptor trigger zone. 

Polar substances cannot reach the emetic center itself because it is protected by the blood-brain barriet However, they can indirectly excite the center by activating chemoreceptors in the area postrema or receptors on peripheral vagal nerve endings. 

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