An erection of the penis occurs when engorgement of venous blood in two tubular structures at the bottom of the penis, the corpora cavernosa, results from a variety of stimuli. The corpus spongiosum is a single tubular structure located just above the corpora carvernonosa, and contains the male urethra, through which urine and semen pass during urination and ejaculation, respectively. This may also become slightly engorged with blood, but less so than the corpora cavernosa. Penile erection usually results from sexual sti ...

Including:

• Erection - Mechanism
• Erection - Dysfunction
• Erection - Concealment
• Erection - Culture
• Erection - Slang
• Erection - Bibliography

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Cardiac output is the volume of blood being pumped by the heart in a minute. It is equal to the heart rate multiplied by the stroke volume. So if there are 70 beats per minute, and 70 ml blood is ejected with each beat of the heart, the cardiac output is 4900 ml/minute. This value is typical for an average adult at rest, although cardiac output may reach up to 30 liters/minute during extreme exercise. When cardiac output increases in a healthy but untrained individual, most of the increase can be attributed to increase i ...

Including:

• Cardiac output - Measuring Cardiac Output
• Cardiac output - The Fick principle
• Cardiac output - Dilution methods
• Cardiac output - Doppler method
• Cardiac output - Impedance plethysmography
• Cardiac output - Equations

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The autonomic nervous system is the part of the nervous system of the higher life forms that is not consciously controlled. It is commonly divided into two usually antagonistic subsystems: the sympathetic and parasympathetic nervous system. The autonomic nervous system controls such vital functions as heart rate, dilation of the bronchioles and dilation and constriction of the pupil; the digestive tract is controlled almost completely by autonomic mechanisms. Autonomic nervous system - Nomenclature. ...

Including:

• Autonomic nervous system - Nomenclature
• Autonomic nervous system - Function
• Autonomic nervous system - Individual components
• Autonomic nervous system - The Cranial Sympathetics
• Autonomic nervous system - Connections with the Spinal Nerves
• Autonomic nervous system - Development

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Atropine is a tropane alkaloid extracted from the deadly nightshade (Atropa belladonna) and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects. Being potentially deadly, it derives its name from Atropos, one of the three Fates who, according to Greek mythology, chose how a person was to die. Atropine - Physiological effects and uses. Generally, atropine lowers the "rest and digest" activity of all muscles and glands ...

Including:

• Atropine - Physiological effects and uses
• Atropine - Ophthalmic use
• Atropine - Resuscitation
• Atropine - Secretions and brochoconstriction
• Atropine - Antidote for organophosphate poisoning
• Atropine - Side effects and overdoses
• Atropine - Chemistry and pharmacology
• Atropine - History
• Atropine - Natural sources

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A synapse is cholinergic if it uses acetylcholine as its neurotransmitter. The parasympathetic nervous system is entirely cholinergic. A cholinergic agent, also known as a parasympathomimetic is a chemical which functions to enhance the effects mediated by acetylcholine in the central nervous system, the peripheral nervous system, or both. These include the acetylcholine receptor agonists musca ...

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The sympathetic nervous system (SNS) is one half of the autonomic nervous system; the parasympathetic nervous system (PNS) is the other. Sympathetic nervous system - Function. The sympathetic nervous system activates what is often termed the "fight or flight response". This response is also known as sympathico-adrenal response of the body, as the pre-ganglionic sympathetic fibers that end in the adrenal medulla (but also all other sympathetic fibers) secrete acetylcholine, which activates t ...

Including:

• Sympathetic nervous system - Function
• Sympathetic nervous system - Organization
• Sympathetic nervous system - Information Transmission

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William James (January 11, 1842, New York – August 26, 1910, Chocorua, New Hampshire) was a pioneering psychologist and philosopher. He wrote influential books on the young science of psychology, psychology of religious experience and mysticism, and the philosophy of pragmatism. William James was born in New York, son of Henry James, Sr., an independently wealthy and notoriously eccentric Swedenborgian theologian well acquainted with the literary and intellectual elites of his day. The intellectual brilliance of the James fam ...

Including:

• William James - Early years
• William James - Professional career
• William James - Writings
• William James - Epistemology
• William James - Cash Value
• William James - Philosophy of religion
• William James - Cash Value of Religion
• William James - Theory of emotion
• William James - William James' bear
• William James - Philosophy of history
• William James - List of major works

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The cranial sympathetics include sympathetic efferent fibers in the oculomotor, facial, glossopharyngeal and vagus nerves, as well as sympathetic afferent in the last three nerves. The Sympathetic Efferent Fibers of the Oculomotor Nerve probably arise from cells in the anterior part of the oculomotor nucleus which is located in the tegmentum of the mid-brain. These preganglionic fibers run with the third nerve into the orbit and pass to the ciliary ganglion where they terminate by forming synapses with sympathetic motor neurons whose ...

See also:

Autonomic nervous system, Autonomic nervous system - Nomenclature, Autonomic nervous system - Function, Autonomic nervous system - Individual components, Autonomic nervous system - The Cranial Sympathetics, Autonomic nervous system - Connections with the Spinal Nerves, Autonomic nervous system - Development

Read more here: » Autonomic nervous system: Encyclopedia II - Autonomic nervous system - The Cranial Sympathetics

There are many invasive and several non-invasive methods for measuring cardiac output in mammals. An extremely crude non-invasive method, often used in the teaching of physiology to under-graduates, reasons as follows: The pressure in the heart rises as blood is forced into the aorta The more stretched the aorta, the greater the pulse pressure In healthy young subjects, each additional 2ml of blood results in a 1 mmHg rise in pressure (This is the crude assumption, which even if the subject did have a See also:

Cardiac output, Cardiac output - Measuring Cardiac Output, Cardiac output - The Fick principle, Cardiac output - Dilution methods, Cardiac output - Doppler method, Cardiac output - Impedance plethysmography, Cardiac output - Equations

Read more here: » Cardiac output: Encyclopedia II - Cardiac output - Measuring Cardiac Output

The use of Digitalis purpurea extract containing cardiac glycosides for the treatment of heart conditions was first described by William Withering. In contemporary medicine, a purer form of digitalis is used to strengthen cardiac contractility (it is a positive inotrope) and as an antiarrhythmic agent to regulate heart rhythm. It is therefore often prescribed for patients in heart failure. A group of pharmacologically active compounds are extracted mostly from the leaves of the second year's growth, and in pure form are referre ...

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Digitalis, Digitalis - General description, Digitalis - Medicinal use, Digitalis - Media, Digitalis - External link

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Insulin - Principles. Insulin is absolutely required for all animal (including human) life. The mechanism is almost identical in nematode worms (e.g. C. elegans), fish, and in mammals. In humans, insulin deprivation due to the removal or destruction of the pancreas leads to death in days or at most weeks. Insulin must be administered to patients in whom there is a lack of the hormone for this, or any other, reason. C ...

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Insulin, Insulin - Discovery and characterization, Insulin - Structure and production, Insulin - Actions on cellular and metabolic level, Insulin - Regulatory action on blood glucose, Insulin - Signal transduction, Insulin - The brain and hypoglycemia, Insulin - Diseases and syndromes caused by an insulin disturbance, Insulin - Insulin as a medication, Insulin - Principles, Insulin - Modes of administration, Insulin - Dosage and timing, Insulin - Types, Insulin - Abuse, Insulin - Timeline

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List of regions in the human brain - Rhombencephalon hindbrain. medulla oblongata medullary pyramids pons fourth ventricle cerebellum cerebellar vermis cerebellar hemispheres anterior lobe posterior lobe flocculonodular lobe cerebellar nuclei

The mechanism of mydriasis depends on the agent being used. It will usually involve either a disruption of the parasympathetic nerve supply to the eye (which causes contraction of the pupil), or over-activity of the sympathetic nervous system (SNS). Atropine blocks muscarinic acetylcholine receptors. Acetylcholine (ACh) is the neurotransmitter of the parasympathetic nervous system and blocking its a ...

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Mydriasis, Mydriasis - Mechanism, Mydriasis - Mydriatics

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Neurotransmitter - Amino acids. Aspartate Glutamate (Glu) γ-Aminobutyric acid (GABA) Glycine (Gly) Neurotransmitter - Biogenic amines. Acetylcholine (Ach) Neurotransmitter - Monoamines. From phenylalanine and tyrosine (catecholamines, in the order of their synthesis): Dop ...

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Neurotransmitter, Neurotransmitter - Types of neurotransmitters, Neurotransmitter - Mechanism of action, Neurotransmitter - Post-synaptic effect, Neurotransmitter - Specific actions, Neurotransmitter - Common neurotransmitters, Neurotransmitter - Amino acids, Neurotransmitter - Biogenic amines, Neurotransmitter - Monoamines, Neurotransmitter - Polypeptides neuropeptides

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Old wives' tale - Eating carrots improves your night vision. Half-truth Carrots do contain vitamin A, which helps to maintain healthy vision, but they do not contain enough to make any significant difference. This tale started in the Second World War when the British spread a rumour that their plane spotters were eating carrots to give them improved vision, concealing the truth about the invention of radar. Old wives' tale - Having sex ...

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Old wives' tale, Old wives' tale - Common old wives' tales, Old wives' tale - Eating carrots improves your night vision, Old wives' tale - Having sex standing up is a contraceptive, Old wives' tale - Chocolate causes acne, Old wives' tale - Masturbation causes blindness, Old wives' tale - Staying out in the cold without a coat causes pneumonia, Old wives' tale - Stepping on a rusty nail causes tetanus, Old wives' tale - Other old wives' tales

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Gastric acid is produced by parietal cells (also known as oxyntic cells) in the stomach. Its secretion is a complex and energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the gastric acid is secreted into the lumen of the stomach. These cells are part of epithelial fundic glands in the gastric mucosa. The pH of gastric acid is 2-3 in the stomach lumen, the acidity being maintained by the proton pump, a H+/K+ ATPase. The parietal cell releases bicarbonate into the blood stream in the process, which causes the temporary rise ...

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Gastric acid, Gastric acid - Physiology, Gastric acid - Regulation of secretion, Gastric acid - Role in disease, Gastric acid - Pharmacology

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Pilocarpine has been used in the treatment of chronic open-angle glaucoma and acute angle-closure glaucoma for over 100 years. It acts on a subtype of muscarinic receptor (M3) found on the iris sphincter muscle, causing the muscle to contract and produce miosis. This opens the trabecular meshwork through increased tension on the scleral spur. This action facilitates the rate that aqueous humor lea ...

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Pilocarpine, Pilocarpine - Clinical uses, Pilocarpine - Adverse effects, Pilocarpine - Sources

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Generally, atropine lowers the "rest and digest" activity of all muscles and glands regulated by the parasympathetic nervous system. This occurs because atropine is a competitive inhibitor of the muscarinic acetylcholine receptors. (Acetylcholine is the neurotransmitter used by the parasympathetic nervous system.) Therefore, it causes swallowing difficulties. Atropine - Ophthalmic use. Topical atropine is used as a cycloplegic, to temporarily paralyze accommodation, and as a mydriatic, to dilate the pupils ...

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Atropine, Atropine - Physiological effects and uses, Atropine - Ophthalmic use, Atropine - Resuscitation, Atropine - Secretions and brochoconstriction, Atropine - Antidote for organophosphate poisoning, Atropine - Side effects and overdoses, Atropine - Chemistry and pharmacology, Atropine - History, Atropine - Natural sources

Read more here: » Atropine: Encyclopedia II - Atropine - Physiological effects and uses

Trimethaphan is a quaternary amine and therefore carries a positive charge. Being charged, it cannot cross lipid cell membranes, such as those that comprise the blood-brain barrier. Due to this, trimethaphan does not have any effect on the central nervous system. The ciliary muscle of the eye functions to round the lens for accommodation and is controlled mainly by parasympathetic system input. With administration of a ganglion-blocking drug, the ciliary muscle cannot contract and the patien ...

See also:

Trimethaphan, Trimethaphan - Effects, Trimethaphan - Therapeutic uses, Trimethaphan - Adverse effects

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Physiologically, an erection is achieved by two mechanisms that play together: increased inflow of blood into the vessels of erectile tissue, and decreased outflow. The vessel system involved is known as the corpora cavernosa and the corpus spongiosum. Muscles in the region relax, allowing more blood to enter these sponge-like tissues. Contraction of other muscles reduce the outflow. The enlarged structure then exerts pressures on the exit veins, further reducing the outflow. As blood flows in, the penis stiffens, its girth and length increases, and it rises to an angle that can vary fro ...

See also:

Erection, Erection - Mechanism, Erection - Dysfunction, Erection - Concealment, Erection - Culture, Erection - Slang, Erection - Bibliography

Read more here: » Erection: Encyclopedia II - Erection - Mechanism