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Peripheral Chemoreceptors
Peripheral chemoreceptors (of the carotid and aortic bodies) are so named because they are sensory extensions of the peripheral nervous system into blood vessels where they detect changes in chemical concentrations. As transducers of patterns of variability in the surrounding environment, carotid and aortic bodies count as chemosensors in a similar way as taste buds and photoreceptors. However, because carotid and aortic bodies detect variation within the body's internal organs, they are considered interoceptors. Taste buds, olfactory bulbs, photoreceptors, and other receptors associated with the five traditional sensory modalities, by contrast, are exteroceptors in that they respond to stimuli outside the body. The body also contains proprioceptors, which respond to the amount of stretch within the organ, usually muscle, that they occupy. As for their particular function, peripheral chemoreceptors help maintain homeostasis in the cardiorespiratory system by monitoring concentrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carotid Body
The carotid body is a small cluster of chemoreceptor cells, and supporting sustentacular cells. The carotid body is located in the adventitia, in the bifurcation (fork) of the common carotid artery, which runs along both sides of the neck. The carotid body detects changes in the composition of arterial blood flowing through it, mainly the partial pressure of arterial oxygen, but also of carbon dioxide. It is also sensitive to changes in blood pH, and temperature. Structure The carotid body is made up of two types of cells, called glomus cells: glomus type I cells are peripheral chemoreceptors, and glomus type II cells are sustentacular supportive cells. * Glomus type I cells are derived from the neural crest. They release a variety of neurotransmitters, including acetylcholine, ATP, and dopamine that trigger EPSPs in synapsed neurons leading to the respiratory center. They are innervated by axons of the glossopharyngeal nerve which collectively are called the carotid sinus ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypoxia (medical)
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either '' generalized'', affecting the whole body, or ''local'', affecting a region of the body. Although hypoxia is often a pathological condition, variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise.. Hypoxia differs from hypoxemia and anoxemia, in that hypoxia refers to a state in which oxygen present in a tissue or the whole body is insufficient, whereas hypoxemia and anoxemia refer specifically to states that have low or no oxygen in the blood. Hypoxia in which there is complete absence of oxygen supply is referred to as anoxia. Hypoxia can be due to external causes, when the breathing gas is hypoxic, or internal causes, such as reduced effectiveness of gas transfer in the lungs, reduced capacity of the blood to carry oxygen, compromised general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart
The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest. In humans, other mammals, and birds, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. Fish, in contrast, have two chambers, an atrium and a ventricle, while most reptiles have three chambers. In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aortic Arch
The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea. Structure The aorta begins at the level of the upper border of the second/third sternocostal articulation of the right side, behind the ventricular outflow tract and pulmonary trunk. The right atrial appendage overlaps it. The first few centimeters of the ascending aorta and pulmonary trunk lies in the same pericardial sheath. and runs at first upward, arches over the pulmonary trunk, right pulmonary artery, and right main bronchus to lie behind the right second coastal cartilage. The right lung and sternum lies anterior to the aorta at this point. The aorta then passes posteriorly and to the left, anterior to the trachea, and arches over left main bronchus and left pulmonary artery, and reaches to the left side of the T4 vertebral body. Apart from T4 vertebral body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Partial Pressure
In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture (Dalton's Law). The partial pressure of a gas is a measure of thermodynamic activity of the gas's molecules. Gases dissolve, diffuse, and react according to their partial pressures but not according to their concentrations in gas mixtures or liquids. This general property of gases is also true in chemical reactions of gases in biology. For example, the necessary amount of oxygen for human respiration, and the amount that is toxic, is set by the partial pressure of oxygen alone. This is true across a very wide range of different concentrations of oxygen present in various inhaled breathing gases or dissolved in blood; consequently, mixture ratios, like that of breathab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neck
The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In addition, the neck is highly flexible and allows the head to turn and flex in all directions. The structures of the human neck are anatomically grouped into four compartments; vertebral, visceral and two vascular compartments. Within these compartments, the neck houses the cervical vertebrae and cervical part of the spinal cord, upper parts of the respiratory and digestive tracts, endocrine glands, nerves, arteries and veins. Muscles of the neck are described separately from the compartments. They bound the neck triangles. In anatomy, the neck is also called by its Latin names, or , although when used alone, in context, the word ''cervix'' more often refers to the uterine cervix, the neck of the uterus. Thus the adjective ''cervical'' ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arteries
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pulmonary and the umbilical arteries, which carry deoxygenated blood to the organs that oxygenate it (lungs and placenta, respectively). The effective arterial blood volume is that extracellular fluid which fills the arterial system. The arteries are part of the circulatory system, that is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, the maintenance of optimum blood pH, and the circulation of proteins and cells of the immune system. Arteries contrast with veins, which carry blood back towards the heart. Structure The anatomy of arteries can be separated into gross anatomy, at the macroscopic level, and microanatomy, which must be studied with a microscop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Transduction
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway. When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling cell growth, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aortic Body
The aortic bodies are one of several small clusters of peripheral chemoreceptors located along the aortic arch. They are important in measuring partial pressures of oxygen and carbon dioxide in the blood, and blood pH. Structure The aortic bodies are collections of chemoreceptors present on the aortic arch. Most are located above the aortic arch, while some are located on the posterior side of the aortic arch between it and the pulmonary artery below. They consist of glomus cells and sustentacular cells. Some sources equate the "aortic bodies" and "paraaortic bodies", while other sources explicitly distinguish between the two. When a distinction is made, the "aortic bodies" are chemoreceptors which regulate the circulatory system, while the "paraaortic bodies" are the chromaffin cells which manufacture catecholamines. Function The aortic bodies measure changes in blood pressure and the composition of arterial blood flowing past it. These changes may include: * oxygen partial pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ventilation (physiology)
Breathing (or ventilation) is the process of moving air into and from the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring in oxygen. All aerobic creatures need oxygen for cellular respiration, which extracts energy from the reaction of oxygen with molecules derived from food and produces carbon dioxide as a waste product. Breathing, or "external respiration", brings air into the lungs where gas exchange takes place in the alveoli through diffusion. The body's circulatory system transports these gases to and from the cells, where "cellular respiration" takes place. The breathing of all vertebrates with lungs consists of repetitive cycles of inhalation and exhalation through a highly branched system of tubes or airways which lead from the nose to the alveoli. The number of respiratory cycles per minute is the breathing or respiratory rate, and is one of the four primary vital signs of life. Under normal conditions th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch, and sometimes the diencephalon is included in the brainstem. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating cardiac, and respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. Ten pairs of cranial nerves come from the brainstem. Other roles include the regulation of the central nervous system and the body's sleep cycle. It is also of prime importance in the conveyance of motor and sensory pathways from the rest of the brain to the body, and from the body back to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afferent Nerves
A sensory nerve, or afferent nerve, is a general anatomic term for a nerve which contains predominantly somatic afferent nerve fibers. Afferent nerve fibers in a sensory nerve carry sensory information toward the central nervous system (CNS) from different sensory receptors of sensory neurons in the peripheral nervous system. A motor nerve carries information from the CNS to the PNS, and both types of nerve are called peripheral nerves. Afferent nerve fibers link the sensory neurons throughout the body, in pathways to the relevant processing circuits in the central nervous system. Afferent nerve fibers are often paired with efferent nerve fibers from the motor neurons (that travel from the CNS to the PNS), in mixed nerves. Stimuli cause nerve impulses in the receptors and alter the potentials, which is known as sensory transduction. Spinal cord entry Afferent nerve fibers leave the sensory neuron from the dorsal root ganglia of the spinal cord, and motor commands carried by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
