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Intrinsic Cardiac Nervous System
The Intrinsic cardiac nervous system (ICNS), also known as the heart's "little brain," is a complex network of neurons and Ganglion, ganglia embedded within the Cardiac muscle, heart tissue that regulates cardiac function independently of the central nervous system. It modulates heart rate, Cardiac conduction system, conduction, and cardiac contractility in response to local and External stimulus, external stimuli. Anatomy The ICNS consists of clusters of neurons, or ganglia, primarily located in the atrial and Ventricle (heart), ventricular walls, with higher concentrations in the Sinoatrial node, sinoatrial (SA) and Atrioventricular node, atrioventricular (AV) nodes. These ganglia contain: * Afferent neurons: Detect mechanical and chemical changes in the heart. * Efferent neurons: Modulate cardiac muscle activity. * Interneurons: Facilitate communication within the ICNS. * The system is organized into Ganglionated plexi, ganglionated plexuses, interconnected by nerve fibers, for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural network in the nervous system. They are located in the nervous system and help to receive and conduct impulses. Neurons communicate with other cells via synapses, which are specialized connections that commonly use minute amounts of chemical neurotransmitters to pass the electric signal from the presynaptic neuron to the target cell through the synaptic gap. Neurons are the main components of nervous tissue in all Animalia, animals except sponges and placozoans. Plants and fungi do not have nerve cells. Molecular evidence suggests that the ability to generate electric signals first appeared in evolution some 700 to 800 million years ago, during the Tonian period. Predecessors of neurons were the peptidergic secretory cells. They eventually ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve Fibers
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system. Each axon is an extension of an individual neuron, along with other supportive cells such as some Schwann cells that coat the axons in myelin. Each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. The entire nerve is wrapped in a layer of connective tissue called the epineurium. Nerve cells (often called neurons) are further classified as either sensory or motor. In the central nervous system, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardiac Ischemia
Coronary ischemia, myocardial ischemia, or cardiac ischemia,Potochny, Evy. "Cardiac Ischemia Symptoms." LiveStrong. Demand Media, 9 March 2010. Web. 6 Nov. 2010. is a medical term for abnormally reduced blood flow in the coronary circulation through the coronary arteries. Coronary ischemia is linked to heart disease, and heart attacks. Coronary arteries deliver oxygen-rich blood to the heart muscle. Reduced blood flow to the heart associated with coronary ischemia can result in inadequate oxygen supply to the heart muscle. When oxygen supply to the heart is unable to keep up with oxygen demand from the muscle, the result is the characteristic symptoms of coronary ischemia, the most common of which is chest pain. Chest pain due to coronary ischemia commonly radiates to the arm or neck. Certain individuals such as women, diabetics, and the elderly may present with more varied symptoms. If blood flow through the coronary arteries is stopped completely, cardiac muscle cells may die, kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardioprotection
Cardioprotection includes all mechanisms and means that contribute to the preservation of the heart by reducing or even preventing myocardial damage. Mechanisms Cardioprotection encompasses several regimens that have shown to preserve function and viability of cardiac muscle cell tissue subjected to ischemic insult or reoxygenation. Cardioprotection includes strategies that are implemented: * before an ischemic event (preconditioning, PC), * during an ischemic event (perconditioning, PerC), * after the event and during reperfusion (postconditioning, PostC). These strategies can be further stratified by performing the intervention locally or remotely, creating classes of conditioning known as remote ischemic PC (RIPC), remote ischemic PostC and remote ischemic PerC. Classical (local) preconditioning has an early phase with an immediate onset lasting 2–3 hours that protects against myocardial infarction. The early phase involves post-translational modification of preexist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purkinje Fibers
The Purkinje fibers, named for Jan Evangelista Purkyně, ( ; ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purkinje fibers are specialized conducting fibers composed of electrically excitable cells. They are larger than cardiomyocytes with fewer myofibrils and many mitochondria. They conduct cardiac action potentials more quickly and efficiently than any of the other cells in the heart's electrical conduction system. Purkinje fibers allow the heart's conduction system to create synchronized contractions of its ventricles, and are essential for maintaining healthy and consistent heart rhythm. Histology Purkinje fibers are a unique cardiac end-organ. Further histologic examination reveals that these fibers are split in ventricles walls. The electrical origin of atrial Purkinje fibers arrives from the sinoatrial node. Given no aberrant channe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HAND2
Heart- and neural crest derivatives-expressed protein 2 is a protein that in humans is encoded by the ''HAND2'' gene. Function The protein encoded by this gene belongs to the basic helix-loop-helix family of transcription factors. This gene product is one of two closely related family members, the HAND proteins Hand1 and Hand2, which are asymmetrically expressed in the developing ventricular chambers and play an essential role in cardiac morphogenesis. Working in a complementary fashion, they function in the formation of the right ventricle and aortic arch arteries, implicating them as mediators of congenital heart disease. In addition, this transcription factor plays an important role in limb and branchial arch development. In one study, it was found that a missense mutation of the Hand2 protein in patients with the congenital heart disease (CHD) Tetralogy of Fallot experienced significantly decreased Hand2 interactions with other key developmental genes such as GATA4 and N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PHOX2B
Paired-like homeobox 2b (PHOX2B), also known as neuroblastoma Phox (NBPhox), is a protein that in humans is encoded by the PHOX2B gene located on chromosome 4. It codes for a homeodomain transcription factor. It is expressed exclusively in the nervous system, in most neurons that control the viscera (cardiovascular, digestive and respiratory systems). It is also required for their differentiation. Immunohistochemistry Essential for the differentiation and survival of sympathetic neurons and chromaffin cells, the transcription factor PHOX2B is highly specific for the peripheral autonomic nervous system. Neuroblasts are derived from sympathoadrenal lineage neural crest cells and therefore require and constitutively express PHOX2B. PHOX2B immunohistochemical staining, as a marker of neural crest derivation, has been shown to be sensitive and specific for undifferentiated neuroblastoma, enabling identification where other markers fail to recognize neuroblastoma among various diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bone Morphogenetic Protein
Bone morphogenetic proteins (BMPs) are a group of growth factors also known as cytokines and as metabologens. Professor Marshall Urist and Professor Hari Reddi discovered their ability to induce the formation of bone and cartilage, BMPs are now considered to constitute a group of pivotal morphogenetic signals, orchestrating tissue architecture throughout the body. The important functioning of BMP signals in physiology is emphasized by the multitude of roles for dysregulated BMP signalling in pathological processes. Cancerous disease often involves misregulation of the BMP signalling system. Absence of BMP signalling is, for instance, an important factor in the progression of colon cancer, and conversely, overactivation of BMP signalling following reflux-induced esophagitis provokes Barrett's esophagus and is thus instrumental in the development of esophageal adenocarcinoma. Recombinant human BMPs (rhBMPs) are used in orthopedic applications such as spinal fusions, nonunions, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placode
In embryology, a neurogenic placode is an area of thickening of the epithelium in the embryonic head ectoderm layer that gives rise to neurons and other structures of the sensory nervous system. Placodes are embryonic structures that give rise to structures such as hair follicles, feathers and teeth. The term "neurogenic placode" generally refers to cranial placodes that have neurogenic potential - i.e. those that give rise to neurons associated with the special senses and cranial ganglia. Cranial placodes include a diverse range of structures found across chordates, but the neurogenic placodes found in vertebrates arose later in evolution. The region in the ectoderm of the developing head that contains all the precursor cells for the cranial placodes is known as the preplacodal region. In humans The cranial placodes that have neurogenic potential (i.e. give rise to neurons) can be divided into two groups, the dorsolateral placodes and the epibranchial placodes. * dorsolater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nodose
The inferior ganglion of the vagus nerve (also known as the nodose ganglion) is one of the two sensory ganglia of each vagus nerve (cranial nerve X). It contains neuron cell bodies of general visceral afferent fibers and special visceral afferent fibers. It is situated within the jugular fossa just below the skull. It is situated just below the superior ganglion of vagus nerve. Anatomy The inferior ganglion of vagus nerve is elongated. It is larger than the superior ganglion of vagus nerve. It is situated within the jugular fossa, just inferior to the jugular foramen. Structure The inferior ganglion contains the neuron cell bodies of all sensory fibres of the CN X except those of the auricular branch of vagus nerve. The neurons in the inferior ganglion of the vagus nerve are pseudounipolar and provide sensory innervation (general somatic afferent and general visceral afferent). The axons of the neurons which innervate the taste buds of the epiglottis synapse in the ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dorsal Aorta
The dorsal aortae are paired (left and right) embryological vessels which progress to form the descending aorta. The paired dorsal aortae arise from aortic arches that in turn arise from the aortic sac. The primary dorsal aorta is located deep to the lateral plate of mesoderm and move from lateral to medial position with development and eventually will fuse with the other dorsal aorta to form the descending aorta. Each primitive aorta anteriorly receives the vitelline vein from the yolk-sac, and is prolonged backward on the lateral aspect of the notochord under the name of the dorsal aorta. The dorsal aortae give branches to the yolk-sac, and are continued backward through the body-stalk as the umbilical arteries The umbilical artery is a paired artery (with one for each half of the body) that is found in the abdominal and pelvic regions. In the fetus, it extends into the umbilical cord. Structure Development The umbilical arteries supply systemic arte ... to the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryonic Development
In developmental biology, animal embryonic development, also known as animal embryogenesis, is the developmental stage of an animal embryo. Embryonic development starts with the fertilization of an egg cell (ovum) by a sperm, sperm cell (spermatozoon). Once fertilized, the ovum becomes a single diploid cell known as a zygote. The zygote undergoes mitosis, mitotic cell division, divisions with no significant growth (a process known as cleavage (embryo), cleavage) and cellular differentiation, leading to development of a multicellular embryo after passing through an organizational checkpoint during mid-embryogenesis. In mammals, the term refers chiefly to the early stages of prenatal development, whereas the terms fetus and fetal development describe later stages. The main stages of animal embryonic development are as follows: * The zygote undergoes a series of cell divisions (called cleavage) to form a structure called a morula. * The morula develops into a structure called a bla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
