crookes tube

Examples of crookes tube in the following topics:

• Cathode Rays

  • Cathode rays are electron beams or streams of electrons that were observed for the first time in Crookes tubes (vacuum tubes).
  • The early cold cathode vacuum tubes, called Crookes tubes, used a high electrical potential between the anode and the cathode to ionize the residual gas in the tube.
  • These were called Crookes tubes.
  • Crookes found that as he pumped more air out of the tubes, the Faraday dark space spread down the tube from the cathode toward the anode, until the tube was totally dark.
  • A Crookes tube is a rarefied tube evacuated to a pressure below 10−6 atm.

• Are Real Dice Fair?

  • Loaded and crooked dice are designed to favor some results over others for purposes of cheating or amusement.
  • A loaded, weighted, or crooked die is one that has been tampered with to land with a specific side facing upwards more often than it normally would.
  • Tappers have a mercury drop in a reservoir at the center, with a capillary tube leading to another reservoir at a side; the load is activated by tapping the die so that the mercury travels to the side.

• Withdrawing Blood

  • A blood collection tube is a sterile glass or plastic tube with a closure.
  • Translucent-topped tubes contain a weaker vacuum in the same sized tube, and will gather less blood.
  • With the vacuum tube system, the needle pierces the top of the sample tube and will potentially come into contact with the additives in the tube.
  • Vacuum tubes for blood collection have colored tops which define the additives to the tube.
  • The gold tube contains a clot activator and gel for serum separation, the green tube contains heparin for clinical chemistry, and the red tube contains a clot activator.

• Embryonic Development

  • The spinal cord derives from the neural tube in two processes: primary and secondary neurulation.
  • The neural folds pinch in towards the midline of the embryo and fuse together to form the neural tube.
  • For a short time, the neural tube is open both cranially and caudally.
  • At the dorsal end of the neural tube, BMPs are responsible for neuronal patterning.
  • Shh secreted from the floor plate creates a gradient along the ventral neural tube.

• Establishing Body Axes during Development

  • The neural tube develops in two ways: primary neurulation and secondary neurulation.
  • Mammalian neural tubes close in the head in the opposite order that they close in the trunk.
  • In the trunk, overlying ectoderm closes, the neural tube closes and neural crest cells migrate.
  • For a short time, the neural tube is open both cranially and caudally.
  • (Neural tube is in green. )

• Female Duct System

  • The fallopian tubes, or oviducts, connect the ovaries to the uterus.
  • The fallopian tubes, also known as oviducts, uterine tubes, and salpinges (singular salpinx) are two very fine tubes lined with ciliated epithelia, leading from the ovaries of female mammals into the uterus, via the utero-tubal junction.
  • The different segments of the fallopian tube are (lateral to medial):
  • the ampullary region that represents the major portion of the lateral tube
  • the isthmus which is the narrower part of the tube that links to the uterus

• Neurulation

  • Following gastrulation, the neurulation process develops the neural tube in the ectoderm, above the notochord of the mesoderm.
  • Neurulation is the formation of the neural tube from the ectoderm of the embryo.
  • By the end of the fourth week of gestation, the open ends of the neural tube (the neuropores) close off.
  • It is the process by which the neural tube at lower levels and caudal to the mid-sacral region is formed.
  • Clinical Example: Spina bifida is a developmental congential disorder caused by the incomplete closing of the neural tube during neurulation.

• Development of the Peripheral Nervous System

  • The peripheral nervous system develops from two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • At this point the future CNS appears as a cylindrical structure called the neural tube, whereas the future PNS appears as two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • The sequence of stages from neural plate to neural tube and neural crest is known as neurulation .
  • During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube.
  • The neural tube will give rise to the central nervous system, while the neural crest will give rise to the peripheral nervous system.

• Capillary Action

  • Notice that the height to which the liquid is lifted is inversely proportional to the radius of the tube, which explains why the phenomenon is more pronounced for smaller tubes.
  • A common apparatus used to demonstrate capillary action is the capillary tube.
  • When the lower end of a vertical glass tube is placed in a liquid, a concave meniscus forms.
  • The rise or fall of liquids in a capillary tube depends upon the interactions between the tube and the liquid.
  • The meniscus curve on a column of fluid in a capillary tube

• Anencephaly

  • Anencephaly (absence of forebrain and neocortex) is a neural tube defect occurring during embryonic development.
  • Anencephaly is a cephalic disorder that results from a neural tube defect that occurs when the cephalic (head) end of the neural tube fails to close, usually between the 23rd and 26th day of pregnancy, resulting in the absence of a major portion of the brain, skull, and scalp.
  • Studies show that a woman who has had one child with a neural tube defect such as anencephaly has about a 3% risk of having another child with a neural tube defect, as opposed to the background rate of 0.1% occurrence in the population at large.
  • Genetic counseling is usually offered to women at a higher risk of having a child with a neural tube defect.
  • Anencephaly is a cephalic disorder that results from a neural tube defect that occurs when the cephalic (head) end of the neural tube fails to close.