Basal Ganglia Made Simple
The basal ganglia form a set of interconnected nuclei in the forebrain.Overall the basal ganglia receive a large amount of input from cerebralcortex, and after processing, send it back to cerebral cortex via thalamus.This major pathway led to the creation of the popular concept of cortico-basalganglia-cortical loops. Inside the basal ganglia there are too manyconnections and pathways to cover in this paragraph. Just briefly:The cortex sends excitatory input to the striatum. The principleneuron of the striatum is the famous medium spiny neuron, which sends itsinhibitory output on to the globus pallidus. The globus palliduscan also be excited by cortical activity, namely by a pathway that travelsthrough the subthalamic nucleus first. The globus pallidus is reallydivided into two segments, only one of which sends output (yet again inhibitory!)to the thalamus and on to cortex, thus completing the loop. The largersegment of globus pallidus (GPe) just inhibits the subthalamic nucleusand itself. The functional significance of this connection is stillquite mysterious! Similar to the cerebellum the basal ganglia arealso implicated in learning, and the system that is thought to be importanthere is the dopaminergic input received from the Substantia nigra parscompacta. Probably the best known fact regarding the basal gangliais that a lesion of this dopaminergic pathway causes Parkinsons disease. Numerous research projects have recorded electrical activity in thebasal ganglia. Unfortunately for the experimentalists seeking clearanswers, the recorded activity in behaving animals can be related justabout to any component of sensory input, motor preparation, and movementexecution. One thing is sure however: The medium spiny neuronsare active only at a very slow rate, and furthermore Continue reading >>
Basal Cell Carcinoma
Print Overview Basal cell carcinoma is a type of skin cancer. Basal cell carcinoma begins in the basal cells — a type of cell within the skin that produces new skin cells as old ones die off. Basal cell carcinoma often appears as a slightly transparent bump on the skin, though it can take other forms. Basal cell carcinoma occurs most often on areas of the skin that are exposed to the sun, such as your head and neck. Most basal cell carcinomas are thought to be caused by long-term exposure to ultraviolet (UV) radiation from sunlight. Avoiding the sun and using sunscreen may help protect against basal cell carcinoma. Symptoms Basal cell carcinoma usually develops on sun-exposed parts of your body, especially your head and neck. This skin cancer appears less often on the trunk and legs, and basal cell carcinoma can — but rarely — occur on parts of your body usually protected from the sun such as genitals or women's breasts. Basal cell carcinoma appears as a change in the skin, such as a growth or a sore that won't heal. These changes in the skin, or lesions, usually have one of the following characteristics: A pearly white, skin-colored or pink bump that is translucent, meaning you can see a bit through the surface. Tiny blood vessels are often visible. In people with darker skin tones, the lesion would be darker but still somewhat translucent. The most common type of basal cell carcinoma, this lesion often appears on the face, ears or neck. The lesion may rupture, bleed and scab over. A brown, black or blue lesion — or a lesion with dark spots — with a slightly raised, translucent border. A flat, scaly, reddish patch with a raised edge is more common on the back or chest. Over time, these patches can grow quite large. A white, waxy, scar-like lesion without a cl Continue reading >>
Also found in: Dictionary, Thesaurus, Legal, Acronyms, Encyclopedia, Wikipedia. Related to basal: Basal temperature, basal metabolic rate basal [ba´sal] pertaining to or situated near a base; in physiology, pertaining to the lowest possible level. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved. ba·sal (bā'săl), [TA] 1. Situated nearer the base of a pyramidal organ in relation to a specific reference point; opposite of apical. Synonym(s): basalis [TA] 2. In dentistry, denoting the floor of a cavity in the grinding surface of a tooth. 3. Denoting a standard or reference state of a function, as a basis for comparison. More specifically, denoting the exact conditions for measurement of basal metabolic rate (q.v.); basal conditions do not always denote a minimum value, for example, metabolic rate in sleep is usually lower than the basal rate but is inconvenient for standard measurement. basal /ba·sal/ (ba´s'l) pertaining to or situated near a base; in physiology, pertaining to the lowest possible level. basal pertaining to the fundamental or the basic, as basal anesthesia, which produces the first stage of unconsciousness, and the basal metabolic rate, which indicates the lowest metabolic rate; basal membrane. basal adjective Referring to a base, baseline or non plus minimum. ba·sal (bā'săl) [TA] 1. Situated nearer the base of a pyramidal organ in relation to a specific reference point; opposite of apical. 2. dentistry Denoting the floor of a cavity in the grinding surface of a tooth. 3. Denoting a standard or reference state of a function, as a basis for comparison. basal Pertaining to, situated at, or forming, an anatomical base of any kind. ba Continue reading >>
What Are Basal And Squamous Cell Skin Cancers?
Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer cells. To learn more about how cancers start and spread, see What Is Cancer? Skin cancer begins when cells in the skin start to grow uncontrollably. Types of skin cells There are 3 main types of cells in the top layer of the skin (called the epidermis): Squamous cells: These are flat cells in the outer part of the epidermis that are constantly shed as new ones form. Basal cells: These cells are in the lower part of the epidermis, called the basal cell layer. These cells constantly divide to form new cells to replace the squamous cells that wear off the skin’s surface. As these cells move up in the epidermis, they get flatter, eventually becoming squamous cells. Melanocytes: These cells make the brown pigment called melanin, which gives the skin its tan or brown color. Melanin acts as the body’s natural sunscreen, protecting the deeper layers of the skin from some of the harmful effects of the sun. For most people, when skin is exposed to the sun, melanocytes make more of the pigment, causing the skin to tan or darken. The epidermis is separated from the deeper layers of skin by the basement membrane. When a skin cancer becomes more advanced, it generally grows through this barrier and into the deeper layers. Types of skin cancer Basal cell carcinoma This the most common type of skin cancer. About 8 out of 10 skin cancers are basal cell carcinomas (also called basal cell cancers). When seen under a microscope, the cells in these cancers look like cells in the lowest layer of the epidermis, called the basal cell layer. These cancers usually develop on sun-exposed areas, especially the head and neck. These cancers tend to grow slowly. It’s very ra Continue reading >>
Basal Ganglia: Definition & Function
Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over 70,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Blood-Brain Barrier: Definition & Function Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Create a new course from any lesson page or your dashboard. Click "Add to" located below the video player and follow the prompts to name your course and save your lesson. Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Name your Custom Course and add an optional description or learning objective. Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course today Try it f Continue reading >>
deciduous - shed annually at the end of the growing season persistent (evergreen) - remaining attached one to several years clustered - in false whorls at tips of lateral spurs, without a basal sheat fascicle - bundle of 2 to 5 leaves enclosed at base by sheath whorled - more than 2 leaves at each node decussate - opposite leaves, each pair at right angles to adjacent pair blade - the flat, expanded portion of a leaf leaflet - a portion of a leaf blade that is subdivided into several smaller blades margin - edge of the leaf simple - not compound, having a single blade compound - composed of 2 or more similar leaflets attached to a rachis petiole - stalk of a leaf stipule - a leaflike appendage of the base of the petiole, usually one on each side of the petiole palmately compound - a leaf composed of several leaflets radially diverging from the petiole like the spread of fingers on a hand pinnately compound - a leaf composed of several leaflets arranged on each side of a common rachis entire - leaf margins without divisions, lobes or teeth lobed - leaf margins with elongated pointed or rounded extensions revolute - leaf margins rolled to underside serrate - leaf margins toothed, teeth pointing upward or forward dentate - leaf margins toothed, teeth pointing directly outward acuminate - lleaf tip gradually tapering to the apex, long pointed acute - leaf tip sharply pointed, but not drawn out notched - leaf tip indented at the apex obtuse - leaf tip blunt or rounded at the apex truncate - leaf tip ending abruptly, as if cut off at end arcuate - leaf veins curved toward apex parallel - having the main veins extending through the leaf longitudinally and in parallel arrangement pinnate - veins arising from each side of a common axis bract - leaflike structure (modified leaf) Continue reading >>
What Is Apical And What Is Basal In Plant Root Development?
What is apical and what is basal in plant root development? Baluka, Frantiek and Barlow, Peter W. and Baskin, Tobias I. and Chen, Rujin J. and Feldman, Lewis and Forde, Brian G. and Geisler, Markus and Jernstedt, Judy and Menzel, Diedrik and Muday, Gloria K. and Murphy, Angus and amaj, Jozef and Volkmann, Dieter (2005) What is apical and what is basal in plant root development? Trends in Plant Science, 10 (9). pp. 409-411. ISSN 1360-1385 Full text not available from this repository. Plant architecture is complex but well described by an established terminology that includes clear definitions of organismal polarity . However, the definitions of polarity that apply to most stages of plant development cannot be applied to early zygotic development. Recent introduction of terminology reserved for early embryonic anatomy to post embryonic seedling anatomy have created some confusion. In this letter, we highlight the issue with the intention of clarifying terminology and bringing about a consensus regarding usage. The original Latin word apex refers to the summit of a hill, mountain or building. According to both the Oxford and Webster dictionaries, apex is defined as the highest or topmost point of a structure. In plants, an apex constitutes the tip of a shoot or a root. The word apical, therefore, means relating to, located or situated at, or constituting, an apex. A base is defined as the lowest or bottom part of an object on which it stands or the main part to which other parts are added. In biology, base means the part of a plant or animal organ that is near the point of attachment to the ground or to a more basal part of the body. Because we cannot say that plants stand on their roots, the base of both stems and roots is actually the same point, and is where the two Continue reading >>
Not to be confused with basil or basel. Basal or basilar is a term meaning base, bottom, or minimum. Science Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure Basal (medicine), a minimal level that is necessary for health or life, such as a minimum insulin dose Basal (phylogenetics), a sister group relationship in a phylogenetic tree Places Basal, Hungary, a village in Hungary Basal, Pakistan, a village in the Attock District Other Basal plate (disambiguation) Basal sliding, the act of a glacier sliding over the bed before it due to meltwater increasing the water pressure underneath the glacier causing it to be lifted from its bed. Continue reading >>