|
Myogenic
The myogenic mechanism is how arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow constant within the blood vessel. Myogenic response refers to a contraction initiated by the myocyte itself instead of an outside occurrence or stimulus such as nerve innervation. Most often observed in (although not necessarily restricted to) smaller resistance arteries, this 'basal' myogenic tone may be useful in the regulation of organ blood flow and peripheral resistance, as it positions a vessel in a preconstricted state that allows other factors to induce additional constriction or dilation to increase or decrease blood flow. The smooth muscle of the blood vessels reacts to the stretching of the muscle by opening ion channels, which cause the muscle to depolarize, leading to muscle contraction. This significantly reduces the volume of blood able to pass through the lumen, which reduces blood flow through the blood vessel. Alternatively when the sm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Myocyte
A muscle cell, also known as a myocyte, is a mature contractile Cell (biology), cell in the muscle of an animal. In humans and other vertebrates there are three types: skeletal muscle, skeletal, smooth muscle, smooth, and Cardiac muscle, cardiac (cardiomyocytes). A skeletal muscle cell is long and threadlike with multinucleated, many nuclei and is called a ''muscle fiber''. Muscle cells develop from embryonic precursor cells called myoblasts. Skeletal muscle cells form by cell fusion, fusion of myoblasts to produce multinucleated cells (syncytium, syncytia) in a process known as myogenesis. Skeletal muscle cells and cardiac muscle cells both contain myofibrils and sarcomeres and form a striated muscle tissue. Cardiac muscle cells form the cardiac muscle in the walls of the heart chambers, and have a single central Cell nucleus, nucleus. Cardiac muscle cells are joined to neighboring cells by intercalated discs, and when joined in a visible unit they are described as a ''cardiac m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Muscle Contraction
Muscle contraction is the activation of Tension (physics), tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state. For the contractions to happen, the muscle cells must rely on the change in action of two types of Myofilament, filaments: thin and thick filaments. The major constituent of thin filaments is a chain formed by helical coiling of two strands of actin, and thick filaments dominantly consist of chains of the Motor protein, motor-protein myosin. Together, these two filaments form myofibrils - the basic functional organelles in the skeletal muscle system. In vertebrates, Muscle cell#Muscle contraction in striated muscle, skele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Smooth Muscle
Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It can be divided into two subgroups, ''single-unit'' and ''multi-unit'' smooth muscle. Within single-unit muscle, the whole bundle or sheet of smooth muscle cells contracts as a syncytium. Smooth muscle is found in the walls of hollow organs, including the stomach, intestines, bladder and uterus. In the walls of blood vessels, and lymph vessels, (excluding blood and lymph capillaries) it is known as vascular smooth muscle. There is smooth muscle in the tracts of the respiratory, urinary, and reproductive systems. In the eyes, the ciliary muscles, iris dilator muscle, and iris sphincter muscle are types of smooth muscles. The iris dilator and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Stretch-activated Ion Channel
Mechanosensitive channels (MSCs), mechanosensitive ion channels or stretch-gated ion channels are membrane proteins capable of responding to mechanical stress over a wide dynamic range of external mechanical stimuli. They are present in the membranes of organisms from the three domains of life: bacteria, archaea, and eukarya. They are the sensors for a number of systems including the senses of touch, hearing and balance, as well as participating in cardiovascular regulation and osmotic homeostasis (e.g. thirst). The channels vary in selectivity for the permeating ions from nonselective between anions and cations in bacteria, to cation selective allowing passage Ca2+, K+ and Na+ in eukaryotes, and highly selective K+ channels in bacteria and eukaryotes. All organisms, and apparently all cell types, sense and respond to mechanical stimuli. MSCs function as mechanotransducers capable of generating both electrical and ion flux signals as a response to external or internal stimuli. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Arteriole
An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillary, capillaries. Arterioles have vascular smooth muscle, muscular walls (usually only one to two layers of smooth muscle cells) and are the primary site of vascular resistance. The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries. This function is extremely important because it prevents the thin, one-layer capillaries from exploding upon pressure. The arterioles achieve this decrease in pressure, as they are the site with the highest resistance (a large contributor to total peripheral resistance) which translates to a large decrease in the pressure. Structure In a healthy vascular system, the endothelium lines all blood-contacting surfaces, including arteries, arterioles, veins, venules, capillaries, and heart chambers. This healthy condition is promoted by the ample production of n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Arterioles
An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primary site of vascular resistance. The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries. This function is extremely important because it prevents the thin, one-layer capillaries from exploding upon pressure. The arterioles achieve this decrease in pressure, as they are the site with the highest resistance (a large contributor to total peripheral resistance) which translates to a large decrease in the pressure. Structure In a healthy vascular system, the endothelium lines all blood-contacting surfaces, including arteries, arterioles, veins, venules, capillaries, and heart chambers. This healthy condition is promoted by the ample production of nitric oxide by the endothelium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Blood Pressure
Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" refers to the pressure in a brachial artery, where it is most commonly measured. Blood pressure is usually expressed in terms of the systolic pressure (maximum pressure during one Cardiac cycle, heartbeat) over diastolic pressure (minimum pressure between two heartbeats) in the cardiac cycle. It is measured in Millimetre of mercury, millimetres of mercury (mmHg) above the surrounding atmospheric pressure, or in Pascal (unit), kilopascals (kPa). The difference between the systolic and diastolic pressures is known as pulse pressure, while the average pressure during a cardiac cycle is known as mean arterial pressure. Blood pressure is one of the vital signs—together with respiratory rate, heart rate, Oxygen saturation (me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cation Channel
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophoric proteins, the other being ion transporters. The study of ion channels often involves biophysics, electrophysiology, and pharmacology, while using techniques including voltage clamp, patch clamp, immunohistochemistry, X-ray crystallography, fluoroscopy, and RT-PCR. Their classification as molecules is referred to as channelomics. Basic features There are two distinctive features of ion channels that differentiate them from other types of ion transporter proteins: # The rate of ion transport thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cardiac Output
In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols Q, \dot Q, or \dot Q_ , edited by Catherine E. Williamson, Phillip Bennett is the volumetric flow rate of the heart's pumping output: that is, the volume of blood being pumped by a single Ventricle (heart), ventricle of the heart, per unit time (usually measured per minute). Cardiac output (CO) is the product of the heart rate (HR), i.e. the number of heartbeats per minute (bpm), and the stroke volume (SV), which is the volume of blood pumped from the left ventricle per beat; thus giving the formula: :CO = HR \times SV Values for cardiac output are usually denoted as L/min. For a healthy individual weighing 70 kg, the cardiac output at rest averages about 5 L/min; assuming a heart rate of 70 beats/min, the stroke volume would be approximately 70 mL. Because cardiac output is related to the quantity of blood delivered to various parts of the body, it is an important com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Paracrine Signalling
In cellular biology, paracrine signaling is a form of cell signaling, a type of cellular communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells. Signaling molecules known as paracrine factors diffuse over a relatively short distance (local action), as opposed to cell signaling by endocrine factors, hormones which travel considerably longer distances via the circulatory system; juxtacrine interactions; and autocrine signaling. Cells that produce paracrine factors secrete them into the immediate extracellular environment. Factors then travel to nearby cells in which the gradient of factor received determines the outcome. However, the exact distance that paracrine factors can travel is not certain. Although paracrine signaling elicits a diverse array of responses in the induced cells, most paracrine factors utilize a relatively streamlined set of receptors and pathways. In fact, different organs in the body - ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
