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Arachnoid Villi and Arachnoid Granulations

By | 2018-07-10T07:43:49+00:00 February 9th, 2018|Nervous system, Physiology|

Arachnoid villi originate from the surface of arachnoid mater and are thin finger-like projections. Human arachnoid villi have four parts: Fibrous capsule Arachnoid cell layer Cap cell cluster Central core They eventually perforate dura in order to project within the dural venous sinuses, before that they move the dura before them. Specific mesothelial cells that [...]

Sensory – Motor Functions and Neurons

By | 2018-07-10T07:44:13+00:00 January 25th, 2018|Nervous system, Physiology|

Neurons come in numerous sizes. For instance, a single sensory neuron from your fingertip has an axon that spreads out the length of your arm, while neurons within the brain may extend just a couple of millimeters. They also have different shapes depending upon their functions. Motor neurons that regulate muscle contractions have a cell [...]

Brainstem – Midbrain and Medulla Oblongata

By | 2018-07-11T05:21:47+00:00 July 24th, 2017|Nervous system, Physiology|

The brainstem is the stalklike portion of the brain that joins higher brain centers to the spinal cord. It contains several nuclei that are surrounded by white matter. Ascending (sensory) and descending (motor) axons between higher brain centers and the spinal cord pass through the brainstem. The components of the brainstem include the midbrain, pons, [...]

Ventricles And Cerebrospinal Fluid

By | 2018-07-11T05:47:00+00:00 July 24th, 2017|Nervous system, Physiology|

There are four interconnecting ventricles, or cavities, within the brain. Each ventricle is lined by ependymal cells and is filled with cerebrospinal fluid (CSF). The largest ventricles are the two lateral ventricles (first and second ventricles), which are located within the cerebral hemispheres. The ihird ventricle is a narrow space that lies on the midline [...]

Excitation – Contraction Coupling

By | 2018-07-11T05:43:09+00:00 July 24th, 2017|Nervous system, Physiology|

The action potential generated at the motor end plate region spreads along the membrane of skeletal muscle cell and into the T tubules. The T tubules contain dihydropyridine receptors that connect to the Ca++ channels of sarcoplasmic reticulum. Depolarization of T tubules opens the sarcoplasmic reticulum Ca++ channels. Calcium exits the sarcoplasmic reticulum and diffuses [...]

Neurological Disorders Affecting Muscles

By | 2018-07-11T05:27:33+00:00 July 24th, 2017|Nervous system, Physiology|

Botulism poisoning is caused by a neurotoxin produced by the bacterium Clostridium botulinum. The toxin prevents release of ACh from the terminal boutons of somatic motor axons. Without prompt treatment with an antitoxin, death may result from paralysis of breathing muscles. Poisoning results from eating improperly canned vegetables or meats that contain C. botulinum and [...]

Divisions of The Nervous System

By | 2018-07-11T05:29:08+00:00 July 24th, 2017|Nervous system, Physiology|

Although the nervous system functions as a coordinated whole, it is divided into anatomical and functional divisions as an aid in understanding this complex organ system. Anatomical Divisions The nervous system has two major anatomical divisions. The central nervous system (CNS) consists of the brain and spinal cord. The CNS is the body's neural integration [...]

Nervous Tissue

By | 2018-07-11T05:30:03+00:00 July 24th, 2017|Nervous system, Physiology|

The nervous system consists of organs composed primarily of nervous tissue supported and protected by connective tissues. There are two types of cells that compose nervous tissue: neurons and neuroglia. Neurons Neurons, or nerve cells, are the structural and functional units of the nervous system. They are delicate cells that are specialized to generate and [...]

Gastric Motility

By | 2018-07-11T06:23:59+00:00 July 24th, 2017|Gastrointestinal System, Nervous system, Physiology|

Stomach The stomach is anatomically and functionally divided into the fundus, body, and antrum. The fundus and body are highly distensible and act as reservoir for the ingested meal. A 1.5 L volume increase causes only a small increase in pressure in the lumen of the stomach. The esophageal swallowing reflex promotes release of NO [...]